Milk production, milk composition, blood composition, and

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Milk production, milk composition, blood composition, and Powered By Docstoc
					  Milk production, milk composition, blood composition,
 and conception rate of transition dairy cows fed different
                  profiles of fatty acids1
                                                  H. V. Petit and C. Benchaar
          Dairy and Swine Research and Development Centre, Agriculture and Agri-Food Canada,
 STN-Lennoxville, Sherbrooke, Quebec, Canada J1M 1Z3 (e-mail: petith@agr.gc.ca). Contribution number 921.
                           Received 22 February 2007, accepted 14 June 2007.

    Petit, H. V. and Benchaar, C. 2007. Milk production, milk composition, blood composition, and conception rate of transition
    dairy cows fed different profiles of fatty acids. Can. J. Anim. Sci. 87: 591–600. A total of 153 lactating Holstein cows averag-
    ing 695 kg body weight (standard error = 11) were allotted 6 wk before the expected date of parturition to 51 groups of three cows
    blocked for similar calving dates to determine the effects of feeding different profiles of fatty acids from 6 wk before calving on
    feed intake, milk production and composition, conception rate, and embryo mortality in the subsequent lactation. Cows within each
    block were assigned to one of the three isoenergetic total mixed diets based on either whole flaxseed (FLA), Megalac® (MEG) or
    micronized soybeans (SOY). Diets were fed for ad libitum intake from 6 wk before calving to day 50 of pregnancy for pregnant
    cows, or 120 d postpartum for those not diagnosed pregnant after artificial insemination (AI). Diet had no effect on prepartum dry
    matter intake but postpartum intake was 9% higher for cows fed FLA than for those fed MEG or SOY. Milk production and fat
    concentration were similar among treatments. Conception rate at first AI was higher for cows fed FLA (54.3%) than for those fed
    SOY (26.9%). Conception rate at first AI was similar for cows fed FLA and MEG and it was similar for those fed MEG and SOY.
    Cows fed MEG tended to have higher embryo mortality than those fed FLA (41.7 vs. 10.5%, P = 0.06) and SOY (41.7 vs. 0%, P
    = 0.08) at first AI and there was no difference among treatments at second AI. Total embryo mortality was similar for cows fed
    FLA and SOY but cows fed MEG had higher total embryo mortality than those fed SOY (35.3 vs. 9.1%) and there was a trend (P
    = 0.07) when MEG was compared with FLA (35.3 vs. 9.5%). These data suggest that feeding flaxseed during the prepartum peri-
    od has little effect on production in the subsequent lactation but could improve fertility of dairy cows.

                                 Key words: Dairy, flaxseed, milk production, reproduction, fatty acids

    Petit, H. V. et Benchaar, C. 2007. Production de lait, composition du lait, composition du sang et taux de conception chez la
    vache laitière recevant différentes sources de gras. Can. J. Anim. Sci. 87: 591–600. Un total de 153 vaches laitières Holstein
    pesant en moyenne 695 kg (erreur standard = 11) ont été distribuées au hasard 6 semaines avant la date prévue de vêlage en 51
    groupes de trois vaches à partir de la semaine 6 avant le vêlage afin de déterminer les effets de différents profils d’acides gras ali-
    mentaires sur l’ingestion, la production et la composition du lait, le taux de conception, et la mortalité embryonnaire lors de la lac-
    tation suivante. Les vaches à l’intérieur de chaque groupe one reçu une des trois rations totales mélangées isoénergétiques basées
    sur du lin (FLA), du Megalac® (MEG) ou du soya micronisé (SOY). Les rations ont été offertes à volonté à partir de 6 semaines
    avant le vêlage jusqu’au jour 50 de gestation pour vaches devenues gestantes ou jusqu’au jour 120 postpartum pour celles non-
    gestantes après la saillie. La ration n’a eu aucun effet sur l’ingestion avant le vêlage mais l’ingestion postpartum a été 9%
    supérieure pour les vaches ayant reçu FLA par rapport à celles ayant reçu MEG ou SOY. La production de lait et la concentration
    de gras ont été semblables pour tous les traitements. Le taux de conception à la première saillie a été supérieur pour les vaches
    ayant reçu FLA (54.3%) comparativement à celles ayant reçu SOY (26.9%) et il n’y a eu aucune différence entre les vaches ayant
    reçu FLA et MEG et entre celles ayant reçu MEG et SOY. Les vaches ayant reçu MEG ont eu tendance à avoir une mortalité
    embryonnaire plus élevée que celles ayant reçu FLA (41.7 vs. 10.5%, P = 0.06) et SOY (41.7 vs. 0%, P = 0.08) à la première sail-
    lie et il n’y a eu aucune différence entre les traitements à la seconde saillie. La mortalité embryonnaire totale a été semblable pour
    les vaches ayant reçu FLA et SOY mais les vaches ayant reçu MEG ont eu une mortalité embryonnaire totale plus élevée que celles
    ayant reçu SOY (35.3 vs. 9.1%) et il y a eu une tendance (P = 0.07) quand MEG a été comparé à FLA (35.3 vs. 9.5%). Ces résul-
    tats suggèrent que l’apport de lin durant la période prepartum a peu d’effet sur la production lors de la lactation suivante mais qu’il
    peut améliorer la fertilité des vaches laitières.

                                   Mots clés: Laitier, lin, production laitière, reproduction, acides gras


The effects of supplemental fat on milk yield and composi-                 transition dairy cows (Skaar et al. 1989; Grum et al. 1996;
tion, intake, and digestion have been extensively investigat-              Selberg et al. 2004; Douglas et al. 2004) and no information
ed in dairy cows. However, only a small number of studies                  was found on the effect of feeding fat to transition cows on
has been performed to determine the effects of dietary fat in              conception rate. Grum et al. (1996) reported that prepartum

Abbreviations: AI, artificial insemination; BW, body weight; DM, dry matter; DMI, dry matter intake; FA, fatty acids;
FLA, flaxseed; MEG, Megalac®; NEFA, non-esterified fatty acids; SOY, micronized soybeans
                                                                     591
592   CANADIAN JOURNAL OF ANIMAL SCIENCE

fat feeding decreases liver lipid and triglyceride concentra-      April 2001, using 33 multiparous [body weight (BW) = 691
tions at calving, which was associated with greater capacity       ± 17] and 30 primiparous (BW = 613 ± 17) Holstein cows.
for oxidation of FA. One recent in vitro study has shown           Cows were blocked within parity for similar expected calv-
that omega 3 FA increase oxidation of FA and the incorpo-          ing dates and there were 11 blocks of multiparous and 10
ration of FA into cellular triglycerides (Mashek et al. 2002),     blocks of primiparous cows. The experiment was carried out
thus indicating a potential to moderate the development of         from 6 wk before the expected calving date up to day 50 of
hepatic lipidosis. However, all FA do not seem to have sim-        pregnancy for pregnant cows, or 120 d postpartum for those
ilar effects and profile of FA may be important. Linolenic         not diagnosed pregnant after artificial insemination (AI).
acid (C18:3) appeared to be one of the most beneficial FA          Cows were housed in tie stalls and fed individually. Cows
because its addition to media resulted in decreased triacyl-       within groups were assigned randomly to one of three treat-
glycerol concentrations and one of the highest rates of glu-       ments. The three total mixed diets (Table 1) consisted of fat
coneogenesis compared with other long-chain FA (Mashek             supplements (Table 2) based on either unprocessed whole
and Grummer 2003). Moreover, Mashek et al. (2005)                  flaxseed (FLA), Megalac® (MEG) or micronized soybeans
reported that cows receiving intravenous infusion of linseed       (SOY) and they were designed at the beginning of the
oil had lower plasma NEFA concentrations than those                experiment to yield similar crude protein and ether extract
receiving infusion of tallow (C18:1) or fish oil (C20:5, C22:6).   concentrations. Precalving diets were formulated to meet
Feeding a source of linolenic acid before calving could then       requirements for cows that averaged 700 kg of BW
contribute to decrease lipid accumulation in the liver and         [National Research Council (NRC) 2001]. After calving,
incidence of fatty liver, thus improving feed intake and milk      diets were formulated to meet requirements for cows that
production in the subsequent lactation as a result of better       averaged 625 kg of BW and produced 40 kg d–1 of milk with
health of dairy cows in the transition period.                     3.85% fat (NRC 2001). Feed consumption was recorded
   Flaxseed contains around 55% of total fat in the form of        daily. Diets were fed twice daily at 0700 and 1500 for 10%
linolenic acid, which makes it a rich source of C18:3.             orts. Samples of diets were taken weekly, frozen, and com-
Flaxseed is an excellent fat source for milk production and        posited on a 4-wk basis. Composited samples were mixed
feeding up to 10% has no effect on DMI of early-lactating          thoroughly and subsampled for chemical analyses. Silage
dairy cows (Petit 2002). Linolenic acid leads to eicosapen-        DM was analyzed weekly for adjustment of the total mixed
taenoic acid formation (Béréziat 1978), which is a precursor       diets. Cows were milked twice daily at 0545 and 1645. Milk
of series 3 prostaglandins (Abayasekara and Wathes 1999).          production was recorded at every milking. Milk samples
Series 3 prostaglandins have lower biological activity than        were obtained once every 4 wk from each cow for two con-
series 2 prostaglandins produced from omega 6 FA (Fly and          secutive milkings and were analyzed separately to deter-
Johnston 1990). Feeding flaxseed has been shown to reduce          mine milk composition. Milk samples were stored at + 4°C
embryo mortality (Petit and Twagiramungu 2006) and                 with a preservative (bronopol-B2) until analyzed 2 d later
secretion of series 2 prostaglandins (Lessard et al. 2003),        for fat, protein, lactose, and SCC and milk samples without
thus improving general fertility of dairy cows (Ambrose et         preservative were frozen at –80°C until analyzed for milk
al. 2006). Lower secretion of series 2 prostaglandins in           FA profile. Yield of 4% fat corrected milk was calculated
blood has been linked to a lower ratio of omega 6 to omega         according to the equation of Tyrrell and Reid (1965).
3 FA in blood (Lessard et al. 2003) and feeding flaxseed           Weight and body condition using a five-point scale (where
results generally in the lowest omega 6 to omega 3 FA ratio        1 = emaciated and 5 = fat, Edmonson et al. 1989) were
in both blood and milk (Petit 2002). A lower omega 6 to            determined weekly for each cow.
omega 3 FA ratio in either blood or milk could then indicate          Blood was collected from all cows 2 wk prepartum, at
better fertility in cows. There is, however, no information on     calving, and 6 wk postpartum to determine non-esterified
                                                                   fatty acids (NEFA) and FA concentrations (1 h before the
the effects of feeding flaxseed from before calving through
                                                                   morning feeding to give a basal value and 3 h postfeeding).
early lactation. Therefore, the objective of this experiment
                                                                   Blood was withdrawn from the jugular vein into vacutainer
was to determine the effects of feeding fat sources with dif-
                                                                   tubes (Becton Dickinson and Cie, Rutherford, NJ) contain-
ferent FA composition, a source of omega 3 (C18:3) FA
                                                                   ing EDTA for fatty acids and NEFA analyses in plasma. The
(flaxseed), omega 6 (C18:2) FA (micronized soybeans), and
                                                                   plasma were separated and frozen at –20°C for subsequent
omega 9 (C18:1) FA (calcium salts of palm oil) to dairy cows
                                                                   analysis. Milk samples were collected on weeks 4 and 8 of
in late gestation and early lactation on performance and con-
                                                                   lactation from the first 10 blocks of multiparous cows to
ception rate. The hypothesis was that feeding flaxseed,
                                                                   calve to determine milk FA composition.
which is a source rich in linolenic acid (C18:3), would               All cows were observed for signs of estrus for a 30-min
increase milk production and feed intake of the transition         period three times daily and were inseminated (by one of
dairy cow and improve conception rate compared to feeding          two technicians) with frozen-thawed semen within 12 h of
fat sources with other profile of fatty acids.                     detected estrus. Estrous detection was performed from day
                                                                   60 to day 120 unless pregnancy occurred. Semen came from
             MATERIALS AND METHODS                                 a single ejaculate of two bulls ensuring that equal numbers
Dairy A                                                            of cows from each treatment group were bred to each bull.
The experiment was conducted at the Dairy and Swine                Ultrasound scanning was performed on days 30 and 50 after
Research and Development Centre from February 2000 to              AI to confirm pregnancy using a Concept\MCV ultrasound
                                             PETIT AND BENCHAAR — FAT SOURCES FOR THE TRANSITION COW                        593

scanner equipped with a linear array 5 MHz probe (Tokyo           total AI) were first analyzed with PROC FREQ of SAS.
Keiki Co. Ltd, Tokyo, Japan). Conception rate was defined         Fisher’s exact tests were used to test the global effect of
as the proportion of cows that were detected in estrus and        treatment on conception rate, embryo mortality, and calving
inseminated that were pregnant on day 30 post AI. Embryo          rate. Comparisons between treatments were obtained using
mortality was calculated as the difference between the num-       the contrast statement of PROC LOGISTIC (SAS Institute,
ber of cows that were pregnant on day 30 and the number of        Inc. 2001) in a completely randomized design where treat-
cows that were pregnant on day 50. Total embryo mortality         ment was the main source of variation in the model.
percentage included mortality for the two AI. Calving rate        Significance was declared at P < 0.05 and a trend at P <
was defined as the proportion of cows that calved/number of       0.10.
cows that were inseminated.
                                                                                RESULTS AND DISCUSSION
Dairy B                                                           The results presented are based on data from 127 cows
The experiment was conducted at the Atlantic Dairy and            (MEG, n = 40; SOY, n = 43; FLA, n = 44) from the original
Forage Institute (ADFI) of Frederiction Junction, NB,             number of cows assigned to the trial. A total of 26 cows
Canada, from September 2000 to January 2003 using 81              (MEG, n = 13; SOY, n = 6; FLA, n = 7) were removed from
multiparous (BW = 732 ± 20) and 9 primiparous (BW = 652           the study due to reasons unrelated to dietary treatments and
± 15) Holstein cows. There were 27 blocks of multiparous          excluded from analyses due to possible confounding effects
and 3 blocks of primiparous cows. Management and record-          on production and reproductive variables of interest.
ing of data were similar to those described above for Dairy          The MEG diet had lower concentrations of ether extract
A, except that the three treatments were formulated to meet       before (Table 1) and after (Table 2) calving than the FLA
requirements for cows that were a mean 650 kg of BW and           and SOY diets at Dairy A and the FLA diet had higher ether
produced 40 kg d–1 of milk with 3.85% fat (NRC 2001).             extract concentrations than the MEG and SOY diets before
                                                                  and after calving at Dairy B. Moreover, at Dairy B, CP con-
Chemical Analysis                                                 centration of the precalving diet was lower for SOY than for
Dry matter of TMR was determined by drying at 105°C for           FLA and MEG. However, the response to dietary treatments
48 h [Association of Official Analytical Chemists (AOAC)          was similar for both sites as shown by the lack of interaction
1990; Method 930.15]. Nitrogen determination was done by          (P > 0.10) between treatment and site with the only excep-
the Kjeldahl method (AOAC 1990). Neutral and acid deter-          tion being for crude protein concentration in milk (P =
gent fibre components were measured according to the non-         0.03); there was no difference in milk crude protein concen-
sequential procedures of Van Soest et al. (1991). Plasma          tration among treatments at Dairy B (2.87, 2.86, and 2.82%
NEFA (kit 99075401; Wako Pure Chemical Industries,                for FLA, MEG and SOY, respectively) but milk crude pro-
Osaka, Japan) concentrations were analyzed by a colorimet-
                                                                  tein concentration was higher for cows FLA (3.08%) than
ric method. Nitrogen, fat, and lactose in milk were deter-
                                                                  for those MEG (2.86%) and SOY (2.82%) at Dairy A (data
mined by infrared spectroscopy (Bentley model 2000;
                                                                  not shown). Therefore, one can presume that although there
Bentley Instrument, Inc., Chaska, MN). Ether extraction in
                                                                  was a confounding effect of diet composition (e.g., crude
diets was conducted with a Soxlec system HT6 apparatus
(Tecator, Fisher Scientific, Montréal, QC) according to the       protein and ether extract concentrations) on production of
method No. 7.060 (AOAC 1990).                                     dairy cows, that effect would have no impact.
   Fatty acids in milk were extracted and methylated accord-         Diets had no effect (P > 0.05) on prepartum DMI,
ing to the method described by Chouinard et al. (1997),           expressed either in kg per day or as a percentage of BW,
while in situ transesterification was performed on diets          BW determined on weeks 6 or 1 before calving, BW change
according to Park and Goins (1994). Plasma FA were                between weeks 6 and 1 before calving, and average BW
extracted according to the procedures outlined by Delbecchi       before calving (Table 3). The only significant difference (P
et al. (2001) and preparation of plasma fatty acid methyl         < 0.05) was due to site with cows at Dairy B consuming
esters was carried out as described by Folch et al. (1957).       more DM prepartum, being heavier 6 wk before calving and
Fatty acid methyl ester profiles were measured by GLC on          on average, and losing more weight between 6 and 1 wk
a Hewlett-Packard 6890 chromatograph (Hewlett-Packard             before calving. The proportion of multiparous cows was
Ltée, Montreal, QC) with a G1315A autosampler equipped            greater at Dairy B (81 out of 90) than Dairy A (33 out of 63),
with a flame ionization detector and a split-splitless injector   which might explain higher DMI and BW for the former.
as described by Delbecchi et al. (2001).                          Treatment had no effect (P > 0.05) on body condition score
                                                                  (data not shown).
Statistical Analysis                                                 There is little information available to evaluate the effect
Data on DMI, milk production and milk and blood compo-            of supplemental fat in the diets on DMI of cows before calv-
sition were analyzed as a randomized block design with            ing. In one study (Selberg et al. 2004), calcium salts of FA
repeated measurements using PROC MIXED of SAS (SAS                were fed in diets that were not isoenergetic and prepartum
Institute, Inc. 2002). Main sources of variation were site,       fat supplementation had no effect on prepartum DMI.
block, treatment and the interaction between site and treat-      Hayirli and Grummer (2004) suggested that cows were
ment. Data on reproduction (estrus detection, conception,         more likely to have had previous exposure to supplemental
embryo mortality, proportion pregnant, calving rate, and          fat than heifers to explain a depression in DMI of heifers but
594     CANADIAN JOURNAL OF ANIMAL SCIENCE

Table 1. Ingredient and chemical composition of the precalving experimental diets (DM basis except DM)y,z
                                                   Dairy A                                                    Dairy B
                                       FLA          MEG            SOY             SE            FLA           MEG            SOY           SE
Ingredient
Corn silage                            33.1          33.7          33.2           26.9           29.6          29.8
Grass silage                           24.0          24.4          24.3           43.5           44.4          44.9
Megalac®                                0             2.7           0              0              2.4           0
Micronized soybean®x                    0             0             9.4            0              0             6.2
Whole flaxseed                          5.9           0             0              5.2            0             0
Protein supplementw                     5.1           7.1           0              9.0            3.9           0
Barley                                  6.2           6.2           6.3           14.2           18.5          16.8
Hay                                    24.8          25.0          25.1            0              0             0
Soybean oil                             0             0             0.7            0              0             0.9
Mineral and vitamin premix              0.9v          0.9v          1.0v           1.2u           1.2u          1.4u

Chemical
DM (%)                                 42.5          39.9          41.0             3.0          42.1          39.9           40.7          1.3
CP (%)                                 14.1          15.5          14.4             0.7          14.7a         14.8a          13.2b         0.3
Ether extract (% of DM)                 4.8a          3.8b          4.9a            0.2           4.3a          3.6b           3.6b         0.3
NDF (% of DM)                          43.0          43.3          45.0             0.7          46.0          46.4           47.5          1.3
ADF (% of DM)                          26.5          27.4          27.2             0.7          26.9          26.7           27.6          0.7
NEL (Mcal kg–1)t                        1.60          1.60          1.59                          1.56          1.58           1.56
RUP (% of N)t                          37.8          37.1          37.6                          33.0          33.0           36.6
NFC (% of DM)t                         29.5          28.7          31.4                          29.5          26.8           27.3

Fatty acids (% of total fatty acids)
C12:0                                   0b            0.8a          0b              0.1         NDs           ND             ND
C14:0                                   0c            1.4a          0.6b            0.1         ND            ND             ND
C16:0                                  12.3c         27.3a         14.6b            0.3         ND            ND             ND
C16:1                                   0c            0.44a         0.32b           0.02        ND            ND             ND
C18:0                                   2.7b          3.1a          3.0a,b          0.1         ND            ND             ND
C18:1                                  17.5b         22.7a         20.3a,b          0.9         ND            ND             ND
C18:2                                  31.7b         31.2b         47.7a            1.5         ND            ND             ND
C18:3                                  35.8a         13.1b         13.5b            2.1         ND            ND             ND
zFLA = fat supplement based on whole flaxseed, MEG = fat supplement based on Megalac, and SOY = fat supplement based on micronized soybeans
yMean of 20 and 6 monthly samples that were prepared by compositing weekly samples at ADFI and at Lennoxville, respectively.
xMICRO-SOYA Elite 40% CP, Semences Prograin Inc. St-Césaire, QC J0L 1T0, Canada.
wContained 52.6% CP, 8.5% ADF, and 13.5% NDF.
vContained 3.0% Ca, 12.0% P, 8.0% Mg, 6.8% Na, 10.5% Cl, 1.5% K, 2.0% S, 40 mg kg–1 of Se, 7700 mg kg–1 of Zn, 200 mg kg–1 of I, 120 mg kg–1 of Co,
6500 mg kg–1 of Mn, 4450 mg kg–1 of Fe, 1600 mg kg–1 of Cu, 800 000 IU kg–1 of vitamin A, 245 000 IU kg–1 of vitamin D, and 7500 IU kg–1 of vitamin
E.
uContained 3.2% Ca, 11.6% P, 21.1% Mg, 1.6% Cl, 0.2% S, 0.2% K, 63 mg kg–1 of Se, 7895 mg kg–1 of Zn, 158 mg kg–1 of I, 53 mg kg–1 of Co, 5342 mg
kg–1 of Mn, 1579 mg kg–1 of Cu, 4211 mg kg–1 of Fe, 63 mg kg–1 of Se, 710 526 IU kg–1 of vitamin A, 236 842 IU kg–1 of vitamin D, and 10 526 IU kg–1
of vitamin E.
tCalculated using published values of feed ingredients (NRC 2001).
sNot determined.
a, b Means within a row and within a site with different letters differ (P < 0.05).



not in cows. Cows at both Dairy A and B have been used                          Cows fed FLA had higher (P < 0.05) postpartum DMI,
previously to study fat supplementation (Petit 2002; Petit et                expressed as kg per day or as a percentage of BW, than
al. 2005), which would agree with that hypothesis.                           those fed MEG and SOY (Table 4) and DMI was similar (P
Moreover, one experiment carried out with ad libitum feed-                   > 0.05) between Dairies. Postpartum supplementation of
ing (Douglas et al. 2004) reported no effect of prepartum                    whole flaxseed, micronized soybeans and calcium salts of
supplementation of fat fed at 6.4% of the dry matter on                      palm oil have resulted in similar DMI and BW change for
prepartum DMI of multiparous cows when using liquid fat.                     the first 16 wk of lactation (Petit 2002). It is unclear why fat
However, in the present experiment, DMI of cows fed the                      supplements similar to those fed in the experiment of Petit
three diets was lower than the NRC (2001) predicted intake,                  (2002) resulted in greater postpartum DMI for cows on the
which would explain the weight loss during the last weeks                    FLA than on the MEG and SOY diets when they were fed
before calving for all cows. It is unclear why actual DMI                    from 6 wk before calving in the present experiment com-
was lower than expected DMI, but differences in diet com-                    pared with when they were fed after calving (Petit 2002).
position might be involved. For example, Ueda et al. (2003)                  However, concentration of ether extract in the three post-
found that the addition of 3% flax oil reduced rumen diges-                  calving diets were below the maximum value of 6 to 7%
tion in a diet containing 33% NDF but not in a diet contain-                 established by the NRC (2001) as having no detrimental
ing 44% NDF.                                                                 effect on DMI of early lactating cows. Intake of individual
                                                      PETIT AND BENCHAAR — FAT SOURCES FOR THE TRANSITION COW                                   595

Table 2. Ingredient and chemical composition of the postcalving experimental diets (DM basis except DM)y,z
                                                       Dairy A                                                   Dairy B
                                         FLA             MEG             SOY              SE          FLA         MEG          SOY         SE
Ingredient
Corn silage                              20.0            24.0            22.1            21.6         22.1        22.2
Grass silage                             33.1            36.5            33.7            32.3         33.2        33.2
Megalac®                                  0               4.9             0               0            5.2         0
Micronized soybean®x                      0               0              14.0             0            0          15.4
Whole flaxseed                           10.8             0               0              12.0          0           0
Protein supplementw                       7.5            10.0             0              12.1         16.4         0
Barley                                   26.2            22.8            25.5            19.1         20.4        25.0
Soybean oil                               0               0               1.2             0            0           0.8
Ammonium phosphate                        0               0               0               0.4          0           0
Magnesium oxide                           0               0               0               0.2          0.9         0.1
Sodium bicarbonate                        0               0               0               0.9          0.8         0.8
Calcium carbonate                         0               0               0               0            0.1         0
Mineral and vitamin premix                2.4v            1.8u            3.5v            1.5t         0.9t        2.5t

Chemical
DM (%)                                   45.7            42.8            44.3             1.8         45.1        43.6         43.2        0.7
CP (%)                                   15.4            15.5            15.3             0.2         15.7b       17.9a        16.6b       0.4
Ether extract (% of DM)                   5.7a            4.7b            5.8a            0.2          6.2a        5.1b         5.1b       0.2
NDF (% of DM)                            35.5            37.3            37.8             0.9         34.7        35.5         35.6        0.7
ADF (% of DM)                            20.5            21.4            20.9             0.8         21.4        22.1         21.1        0.4
NEL (Mcal kg–1)s                          1.72            1.72            1.72                         1.67        1.71         1.68
RUP (% of N)s                            40.8            40.4            48.1                         37.2        36.1         44.6
NFC (% of DM)s                           39.2            37.6            41.1                         37.1        34.3         35.9

Fatty acids (% of total fatty acids)
C12:0                                     0b              0.9a            0b              0.1        NDr         ND           ND
C14:0                                     0c              1.8a            0.5b            0.1        ND          ND           ND
C16:0                                    10.2b           33.4a           12.9b            0.8        ND          ND           ND
C16:1                                     0c              0.32a           0.23b           0.01       ND          ND           ND
C18:0                                     2.6c            3.3a            3.1b            0.03       ND          ND           ND
C18:1                                    16.4c           27.3a           23.2b            0.4        ND          ND           ND
C18:2                                    27.1b           25.7b           47.8a            1.6        ND          ND           ND
C18:3                                    43.7a            7.3c           12.3b            1.1        ND          ND           ND
zFLA = fat supplement based on whole flaxseed, MEG = fat supplement based on Megalac, and SOY = fat supplement based on micronized soybeans.
yMean of 26 and 16 monthly samples that were prepared by compositing weekly samples at ADFI and at Lennoxville, respectively.
xMICRO-SOYA Elite 40% CP, Semences Prograin Inc. St-Césaire, QC J0L 1T0, Canada.
wContained 52.6% CP, 8.5% ADF, and 13.5% NDF.
vContained 8.8% Ca, 12.0% P, 4.5% Mg, 14.5% Na, 2.1% S, 1.5% K, 14 mg kg–1 of Se, 2415 mg kg–1 of Zn, 65 mg kg–1 of I, 35 mg kg–1 of Co, 2179 mg
kg–1 of Mn, 533 mg kg–1 of Cu, 2255 mg kg–1 of Fe, 380 400 IU kg–1 of vitamin A, 77 700 IU kg–1 of vitamin D, and 1800 IU kg–1 of vitamin E.
uContained 9.0% Mg, 20.5% Na, 5.0% S, 4.2% K, 31.5% Cl, 40 mg kg–1 of Se, 7500 mg kg–1 of Zn, 200 mg kg–1 of I, 120 mg kg–1 of Co, 6450 mg kg–1 of
Mn, 1600 mg kg–1 of Cu, 270 mg kg–1 of Fe, 800 000 IU kg–1 of vitamin A, 245 000 IU kg–1 of vitamin D, and 3250 IU kg–1 of vitamin E.
tContained 20.0% Ca, 6.4% P, 3.8% Mg, 7.2% Na, 0.7% S, 12 mg kg–1 of Se, 4000 mg kg–1 of Zn, 80 mg kg–1 of I, 20.0 mg kg–1 of Co, 2000 mg kg–1 of
Mn, 600 mg kg–1 of Cu, 3000 mg kg–1 of Fe, 270 000 IU kg–1 of vitamin A, 80 000 IU kg–1 of vitamin D, and 1200 IU kg–1 of vitamin E.
sCalculated using published values of feed ingredients (NRC 2001).
rNot determined.
a–c Means within a row and within a site with different letters differ (P < 0.05).




FA was calculated using the mean values of dietary FA pro-                              Milk production was similar (P > 0.05) among treat-
file and fat concentration and DMI. Daily average intakes of                         ments, which disagrees with the results of Petit (2002), who
C12:0, C14:0, C16:0, C16:1, C18:0, C18:1, C18:2, and C18:3 were,                     reported higher milk yield for cows fed whole flaxseed com-
respectively, 0, 0, 112, 0, 29, 180, 298, and 481 g for cows                         pared with those fed calcium salts of palm oil during the
fed FLA. Cows fed SOY consumed, respectively, 0, 5, 132,                             postpartum period. Douglas et al. (2004) reported no effect
3, 32, 238, 491, and 126 g per day of C12:0, C14:0, C16:0,                           of prepartum supplementation with 6.5% fat containing
C16:1, C18:0, C18:1, C18:2, and C18:3 and cows fed MEG con-                          46% C18:1 on milk production for the first 105 d of lactation
sumed, respectively, 7, 15, 278, 3, 27, 227, 214, and 60 g per                       when cows were fed the same postpartum diet. Cows fed
day of C12:0, C14:0, C16:0, C16:1, C18:0, C18:1, C18:2, and C18:3.                   FLA had greater (P < 0.05) DMI but similar (P > 0.05) milk
Therefore, cows fed FLA would have had higher intakes of                             yield than those fed the two other diets, which may result of
C18:3 than those fed MEG and SOY. On the other hand,                                 lower fibre digestibility for diets based on whole flaxseed
cows fed SOY would have consumed greater amounts of                                  than for those based on micronized soybeans or calcium
C18:2 than those fed FLA and MEG.                                                    salts of palm oil (Petit 2002). Milk fat concentration was
596     CANADIAN JOURNAL OF ANIMAL SCIENCE

Table 3. Prepartum feed intake and body weight change of Holstein cows fed a concentrate based on whole flaxseed (FLA), Megalac (MEG) or
micronized soybeans (SOY) z
                                                           Treatment                                             Site
Item                                        FLA              MEG         SOY              SE          Dairy A            Dairy B       SE
DMI (kg d–1)                                11.0             11.2        10.6             0.4          12.3a               9.6b        0.4
DMI (% of BW)                                1.64             1.65        1.59            0.05          1.74a              1.51b       0.05
BW (kg)
6 wk before calving                        707              697         701              12           734a               669b         10
1 wk before calving                        695              686         696              13           689                695          11
BW change (kg)                             –12              –11          –5               7           –46b                26a          6
Average BW (kg)                            692              695         697              11           711a               678b         10
a, b Means within site with different letters differ (P < 0.05).
zLeast squares means with pooled standard error (SE).




Table 4. Average DMI, milk production and composition and body weight of Holstein cows fed a concentrate based on whole flaxseed (FLA), Megalac
(MEG) or micronized soybeans (SOY) between calving and week 16 of lactationz
                                                           Treatment                                              Site
Item                                        FLA              MEG         SOY              SE          Dairy A             Dairy B      SE
DMI (kg d–1)                                19.3a            17.7b       17.7b             0.4          18.6               17.9         0.3
DMI (% of BW)                                3.22a            2.97b       2.98b            0.05          3.08               3.03        0.05
Milk production (kg d–1)                    30.3             31.3        31.0              0.8          31.8c              29.7d        0.7
Milk composition (%)
fat                                          3.86             3.88        3.78             0.08          4.08c              3.60d       0.06
protein                                      2.98             2.86        2.82             0.03          2.86               2.91        0.03
SCSy                                         4.24             4.18        4.32             0.18          4.15               4.35        0.15
4% FCMx (kg d–1)                            29.8             31.4        30.1              0.8          32.6c              28.3d        0.7
Production (kg d–1)
fat                                          1.17             1.24        1.18             0.03          1.31c              1.08d       0.03
protein                                      0.91             0.91        0.88             0.02          0.92               0.88        0.02
BW (kg)
Week 1                                     646              626         632               15           646                624         13
Week 16                                    615              607         603               12           614                603         10
BW change (kg)                             –31              –20         –29               10           –32                –21          8
Average BW (kg)                            603              597         600                9           604                596          7
zLeast squares means    with pooled standard error (SE).
ySomatic cell score =   log10SCC.
xfat corrected milk.
a, b Means within treatment with different letters differ (P < 0.05).
c, d Means within site with different letters differ (P < 0.05).


similar (P > 0.05) among treatments and slow release of oil                       0.05) in milk fat of cows fed SOY than in milk fat of those
from soybeans in the rumen has been shown not to affect                           fed FLA as previously reported by Abel-Caines et al. (1998)
milk fat concentration (Dhiman et al. 2000). Yields of fat                        who compared nonenzymatically browned soybeans and
and protein, SCS, BW on weeks 1 and 16, BW change, and                            Megalac®. Soybeans are rich in 18:2, probably reflecting its
average BW were similar (P > 0.05) among treatments.                              high transfer efficiency from the diet to the milk fat
   Milk FA concentrations (Table 5) of 10:0, 18:0, and cis 3-                     (Dhiman et al. 1995). Cows fed SOY consumed 164% of the
18:3 were higher (P < 0.05) for cows fed FLA than for those                       theoretical daily amount of C18:2 consumed by cows fed
fed MEG while the inverse was observed for concentration                          FLA (490 vs. 298 g d–1). Feeding FLA resulted in the low-
of 16:0. This is in general agreement with the results of Petit                   est (P < 0.05) omega 6 to omega 3 FA ratio in milk, which
et al. (2001) and Petit (2002), who compared, respectively,                       would improve the nutritive value of milk from a human
formaldehyde-treated flaxseed with Megalac® and untreated                         health point of view. According to Sim (1998) the current
whole flaxseed with Megalac®. Concentrations of 12:0,                             high ratio should be decreased to less than 4 to 1 to reduce
14:0, 14:1, 16:1, cis11-18:1, cis 9-18:1, trans 6-18:2, cis 6-                    the potential risk of coronary heart diseases; feeding whole
20:3, and cis 6-20:4 were similar (P > 0.05) among diets.                         untreated flaxseed to dairy cows could contribute in improv-
Feeding SOY compared with FLA increased (P < 0.05) con-                           ing human health by a greater intake of omega 3 FA in
centrations of trans 9-18:1. Elaidic acid (trans 9-18:1) is                       enriched dairy products.
produced by the action of microbes in the rumen (Abu-                                There was no interaction between diet and week for plas-
Ghazaleh et al. 2002), suggesting that biohydrogenation of                        ma concentrations of NEFA and individual FA except for
polyunsaturated FA was greater in micronized soybeans                             cis 3-18:3 concentration (P = 0.04); concentration of plasma
than flaxseed. Concentrations of cis 6-18:2 was higher (P <                       cis 3-18:3 increased significantly from calving up to week 6
                                                      PETIT AND BENCHAAR — FAT SOURCES FOR THE TRANSITION COW                               597

Table 5. Average milk fatty acid composition of Holstein cows fed a total mixed diet containing whole flaxseed (FLA), Megalac (MEG) or micronized
soybeans (SOY)z
Item                                       FLA                                 MEG                                SOY                      SE
                                                                                       (% of total fatty acids)

10:0                                        2.6a                                1.9b                               2.0a,b                  0.2
12:0                                        2.7                                 2.1                                2.1                     0.2
14:0                                        8.9                                 7.4                                7.6                     0.5
14:1                                        0.7                                 0.6                                0.6                     0.1
16:0                                       24.9b                               33.1a                              24.7b                    0.4
16:1                                        2.2                                 2.1                                1.9                     0.1
18:0                                       18.1a                               13.9b                              18.9a                    0.5
cis 11-18:1                                 0.9                                 0.8                                0.8                     0.1
cis 9-18:1                                 33.0                                31.8                               32.0                     1.1
trans 9-18:1                                1.8b                                2.1b                               3.3a                    0.2
cis 6-18:2                                  2.6b                                3.1b                               4.6a                    0.2
trans 6-18:2                                0.1                                 0.2                                0.2                     0.1
cis 3-18:3                                  1.2a                                0.6b                               1.0a                    0.1
cis 6-20:3                                  0.1                                 0.1                                0.1                     0.1
cis 6-20:4                                  0.2                                 0.2                                0.2                     0.1
Omega-6                                     3.0b                                3.6b                               5.0a                    0.3
Omega-3                                     1.2a                                0.6b                               1.0a                    0.1
Omega-6/omega-3                             2.7c                                6.0a                               5.1b                    0.2
PUFA                                        4.2b                                4.2b                               6.0a                    0.3
Saturated                                  57.2                                58.4                               55.4                     1.3
Unsaturated                                42.8                                41.6                               44.6                     1.3
zLeast squares means with pooled standard error (SE).
a–c Means within a row with different letters differ (P < 0.05).


Table 6. Blood composition of transition Holstein cows fed a total mixed diet containing whole flaxseed (FLA), Megalac (MEG) or micronized soy-
beans (SOY)z
                                                         Treatment                                                   Week
Item                                         FLA            MEG          SOY            SE              -2              0        6         SE
NEFA (µEq    L–1)                           470            663          479            78            262d          1043c       307d       70
Fatty acid (% of total fatty acids)
14:0                                          1.4a           1.3ab        1.1b          0.1             1.1d           1.8c      0.9d      0.1
16:0                                         14.3b          17.9a        14.0b          0.5            14.2d          18.3c     13.7d      0.5
16:1                                          1.9a           1.7a         1.4b          0.1             1.3d           2.4c      1.4d      0.1
18:0                                         17.0a          14.3b        15.2a,b        0.7             8.1c          14.1d     14.3d      0.7
trans 9-18:1                                  0.8b           0.9a,b       1.1a          0.1             0.8            1.1       0.1       0.1
cis 9-18:1                                   12.4a          13.8a         9.7b          0.6             9.3d          17.7c      8.9d      0.6
cis 11-18:1                                   0.59a          0.59a        0.40b         0.04            0.39d          0.71c     0.49d     0.04
18:2                                         35.3b          41.2a        45.0a          1.6            37.0d          35.3d     49.2c      1.6
cis 3-18:3                                    7.6a           3.8b         4.0b          0.3             4.8d           4.7d      5.8c      0.3
cis 6-20:3                                    1.5            1.5          1.4           0.1             1.7c           1.2d      1.6c,d    0.1
20:4                                          1.5            1.7          1.5           0.1             1.6c,d         1.7c      1.4d      0.1
cis 3-20:5                                    0.6a           0.3b         0.3b          0.1             0.4            0.3       0.4       0.1
omega-6/omega-3                               4.9b          11.1a        11.4a          0.4             8.9c,d         8.6d      9.9c      0.4
zLeast squares means with pooled standard error (SE).
a, b Means within treatment with different letters differ (P < 0.05).
c, d Means within week with different letters differ (P < 0.05).



of lactation for cows fed FLA while it remained similar for                    Plasma NEFA concentration increased from 2 week before
those fed MEG or SOY (data not shown), which would                             calving until calving before to decrease to reach precalving
result from the greater 18:3 concentration in the FLA diet                     levels on week 6 postcalving. This agrees with higher con-
than in those based on MEG or SOY (Table 2). Cows fed                          centrations of blood NEFA generally reported at calving
MEG tended (P = 0.09) to have higher plasma NEFA con-                          (Rukkwamsuk et al. 1999). Feeding FLA compared with
centrations than those fed FLA (Table 6), which has been                       SOY increased (P < 0.05) plasma concentrations of 14:0,
related to greater susceptibility to develop fatty liver (Skaar                16:1, cis 9-18:1, cis 11-18:1, cis 3-18:3, and cis 3-20:5 and
et al. 1989; Vasquez-Ãnon et al. 1994). Mashek et al. (2005)                   decreased (P < 0.05) those of trans 9-18:1 and 18:2. Cows
previously reported that cows infused intravenously with                       fed MEG had higher (P < 0.05) plasma concentrations of
emulsion of tallow, rich in 18:1, had higher plasma NEFA                       18:2 and lower ones (P < 0.05) of 18:0, cis 3-18:3, and cis
concentrations than those infused with linseed oil emulsion.                   3-20:5 than those fed FLA.
598    CANADIAN JOURNAL OF ANIMAL SCIENCE


Table 7. Gestation rate and embryo mortality of Holstein cows fed between calving and d 50 of gestation a concentrate based on whole flaxseed
(FLA), Megalac (MEG) or micronized soybeans (SOY)
                                                                                                                 P
Item                               FLA                 MEG            SOY              FLA vs. MEG          FLA vs. SOY        MEG vs. SOY
Estrus detection
at first AI
%                                   79.5                75.0           60.5                0.61                 0.18               0.64
no./no.                            35/44               30/40          26/43
At second AI
%                                  29.6                 31.3           22.9                0.89                 0.79               0.60
no./no.                            8/27                10/32           8/35
Conception
at first AI,z
%                                   54.3                40.0           26.9                0.25                 0.05               0.98
no./no.                            19/35               12/30           7/26
at second AI,z
%                                  11.8                23.8            22.2                0.35                 0.34               0.50
no./no.                            2/17                5/21            4/18
Embryo mortality
at first AI,y
%                                  10.5                41.7             0                  0.06                 0.95               0.08
no./no.                            2/19                5/12            0/7
at second AI,y
%                                    0                 20.0            25.0                1.00                 1.00               0.99
no./no.                             0/2                1/5             1/4
Total embryo mortality
%                                   9.5                35.3             9.1                0.07                 0.39               0.04
no./no.                            2/21                6/17            1/11
Proportion pregnant
%                                   43.2                27.5           23.3                0.14                 0.04               0.58
no./no.                            19/44               11/40          10/43
Calving rate
%                                   34.1               22.5            20.9                0.24                 0.13               0.59
No./no.                            15/44               9/40            9/43
Total AI, no.                        35                 30              26                 0.18                 0.23               0.99
Days open                           65.2               68.8            65.9                0.86                 0.99               0.93
zDetermined   by ultrasound on day 30 post AI.
yDetermined   by rectal palpation on day 50 post AI.


   Plasma concentrations of 14:0, 16:0, 16:1, cis 9-18:1, and               Estrous detection percentages at first and second AI were
cis 11-18:1 were higher (P < 0.05) at calving than 2 wk                  similar (P > 0.05) among treatments (Table 7), which would
prepartum and 6 wk postpartum and there were no differ-                  suggest that estrous behaviour was not affected by diet.
ences (P > 0.05) between 2 wk prepartum and 6 wk post-                   Similarly, feeding either whole flaxseed, calcium salts of
partum (Table 6). Plasma concentrations of 18:2 and cis                  palm oil or micronized soybeans after calving had no effect
3-18:3 were higher (P < 0.05) at week 6 postpartum than at               on estrous detection percentage (Petit and Twagiramungu
week 2 prepartum and at calving. According to                            2006). Moreover, fish meal, which is rich in omega 3 FA,
Rukkwamsuk et al. (2000) more intensive lipolysis results                had no effect on estrous detection of early lactating dairy
in increased concentrations of 16:0, 18:0, 18:1, and 18:2 in             cows prior to estrous synchronization (Burke et al. 1997).
blood, which would agree with the fact that these FA were                Conception rate at first AI was higher (P < 0.05) for cows
in greater concentrations at calving. The omega 6 to omega               fed FLA (54.3%) than for those fed SOY (26.9%).
3 FA ratio in plasma increased (P < 0.05) from calving to                Conception rate was similar (P > 0.05) for cows fed FLA
week 6 postpartum.                                                       and MEG and it was similar (P > 0.05) for those fed MEG
   Intake of DM is inversely related to concentrations of                and SOY. Conception rate at second AI was similar (P >
NEFA in plasma and triglycerides in the liver (Bertics et al.            0.05) among treatments. Cows fed MEG tended to have
1992), which agrees with the lower DMI and the higher con-               higher embryo mortality than those fed FLA (41.7 vs.
centrations of NEFA in plasma of cows fed MEG compared                   10.5%, P = 0.06) and SOY (41.7 vs. 0%, P = 0.08) and there
with those fed FLA. On the other hand, cows fed SOY had                  was no difference (P > 0.10) among treatments at second
lower DMI than those fed FLA but similar plasma NEFA                     AI. Total embryo mortality was similar (P > 0.05) for cows
concentrations and BW change. Polyunsaturated FA are                     fed FLA and SOY but cows fed MEG had higher (P < 0.05)
known to up-regulate FA oxidation in the liver (Sessler and              total embryo mortality than those fed SOY (35.3 vs. 9.1%)
Ntambi 1998) but the effect of dietary polyunsaturated FA                and there was a trend (P = 0.07) when MEG was compared
on plasma NEFA concentrations differs as previously                      with FLA (35.3 vs. 9.5%). The overall proportion pregnant
shown by Mashek et al. (2005).                                           was significantly higher (P < 0.05) for cows fed FLA
                                               PETIT AND BENCHAAR — FAT SOURCES FOR THE TRANSITION COW                                  599

(43.2%) than for those fed SOY (23.3%) and there was no               Ambrose, D., Kastelic, J. P., Corbett, R., Pitney, P. A., Petit, H.
difference (P > 0.05) between cows fed FLA and MEG and                V., Small, J. A. and Zalkovic, P. 2006. Lower pregnancy losses
between those fed MEG and SOY. Differences in the total               in lactating dairy cows fed a diet enriched in alpha-linolenic acid.
number of cows per treatment may be responsible for the               J. Dairy Sci. 89: 3066–3074.
lack of power when comparing treatments. Comparison                   Association of Official Analytical Chemists. 1990. Official
                                                                      methods of analysis. 15th. ed. AOAC, Washington, DC.
between FLA and SOY was more powerful than with MEG                   Béréziat, G. 1978. Voies métaboliques et régulations de la biosyn-
and FLA as a result of the number of cows being more sim-             thèse des prostaglandines et thromboxanes. Rev. Fr. Corps Gras
ilar for the former contrast. Calving rate, total AI, and num-        25: 463–473.
ber of days open were similar (P > 0.05) among treatments.            Bertics, S. J., Grummer, R. R., Cadorniga-Valino, C. and
Feeding flaxseed compared with micronized soybeans, a                 Stoddard, E. E. 1992. Effect of prepartum dry matter intake on
source of omega 6 FA or Megalac®, a source of calcium                 liver triglyceride concentration and early lactation. J. Dairy Sci. 75:
salts of palm oil has been shown to reduce embryo mortali-            1914–1922.
ty (Petit and Twagiramungu 2006) and secretion of series 2            Burke, J. M., Staples, C. R., Risco, C. A., De la Sota, R. L. and
prostaglandins (Lessard et al. 2003). It has also been report-        Thatcher, W. W. 1997. Effect of ruminant grade menhaden fish
ed that feeding flaxseed increases the size of the ovulatory          meal on reproductive and productive performance of lactating
follicle and reduces pregnancy losses (Ambrose et al. 2006).          dairy cows. J. Dairy Sci. 80: 3386–3398.
                                                                      Chouinard, P. Y., Girard, V. and Brisson, G. J. 1997.
Feeding flaxseed could then contribute in improving fertili-          Performance and profiles of milk fatty acids of cows fed full-fat,
ty of dairy cows.                                                     heat-treated soybeans using various processing methods. J. Dairy
                                                                      Sci. 80: 334–342.
                      CONCLUSIONS                                     Delbecchi, L., Ahnadi, C. E., Kennelly, J. J. and Lacasse, P.
Feeding whole flaxseed compared with Megalac® or                      2001. Milk fatty acid composition and mammary lipid metabolism
micronized soybeans had no effect on prepartum DMI, but               in Holstein cows fed protected or unprotected canola seeds. J.
it increased postpartum DMI of dairy cows. Dietary fat                Dairy Sci. 84: 1375–1381.
sources had no effect on milk composition, milk production,           Dhiman, T. R., Zanten, K. V. and Satter, L. D. 1995. Effect of
and body weight change. Cows fed flaxseed had the highest             dietary fat source on fatty acid composition of cow’s milk. J. Sci.
plasma concentration of linolenic acid. Conception rate at            Food Agric. 69: 101–107.
first AI was higher for cows fed flaxseed than for those fed          Dhiman, T. R., Satter, L. D., Pariza, M. W., Galli, M. P.,
                                                                      Albridht, K. and Tolosa, M. X. 2000. Conjugated linoleic acid
micronized soybeans and there was no difference between               (CLA) content of milk from cows offered diets rich in linoleic and
cows fed flaxseed and those fed calcium salts of palm oil.            linolenic acid. J. Dairy Sci. 83: 1016–1027.
Cows fed calcium salts of palm oil had higher total embryo            Douglas, G. N., Overton, T. R., Bateman II, H. G. and
mortality than those fed micronized soybeans, and there was           Drackley, J. K. 2004. Peripartal metabolism and production of
a trend (P = 0.07) when compared with cows fed flaxseed.              Holstein cows fed diets supplemented with fat during the dry peri-
The overall proportion pregnant was significantly higher for          od. J. Dairy Sci. 87: 4210–4220.
cows fed flaxseed than for those fed micronized soybeans.             Edmonson, A. J., Lean, I. J., Weaver, L. D., Farver, T. and
These data suggest that feeding flaxseed during the prepar-           Webster, G. 1989. A body condition scoring chart for Holstein for
tum period has little effect on production in the subsequent          dairy cows. J. Dairy Sci. 72: 68–78.
                                                                      Fly, A. D. and Johnston, P. V. 1990. Tissue fatty acid composi-
lactation. However, feeding flaxseed contributes to improve           tion, prostaglandin synthesis, and antibody production in rats fed
fertility of dairy cows due to a decrease in embryo mortali-          corn, soybean, or low erucic acid rapeseed oil (canola oil). Nutr.
ty and increase in conception rate.                                   Res. 10: 1299–1310.
                                                                      Folch, J., Lees, M. and Sloane-Stanley, G. H. 1957. A simple
                  ACKNOWLEDGMENTS                                     method for the isolation and purification of total lipids from animal
The authors thank N. Clark, J. Sweetland, L. Veilleux, and            tissues. J. Biol. Chem. 226: 497–509.
I. Sabourin for technical assistance, S. Méthot for his help in       Grum, D. E., Drackley, J. K., Younker, R. S., LaCount, D. W.
analysing the data, and the Atlantic Dairy and Forage                 and Veenhuizen, J. J. 1996. Nutrition during the dry period and
Institute, Fredericton Junction, NB E5L 1R1 and Semences              hepatic lipid metabolism of periparturient dairy cows. J. Dairy Sci.
                                                                      79: 1850–1864.
Prograin Inc., St-Césaire, QC J0L 1T0 for their financial             Hayirli, A. and Grummer, R. R. 2004. Factors affecting dry mat-
help. This project was sponsored in part by the Matching              ter intake prepartum in relationship to etiology of peripartum lipid-
Investment Initiative of Agriculture and Agri-Food Canada.            related metabolic disorders: a review. Can. J. Anim. Sci 84:
                                                                      337–347.
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ing dietary fatty acid composition on prostaglandin synthesis and     response of postpartum dairy cows fed flaxseed. J. Dairy Sci. 86:
fertility. Prostaglandins, Leukot. Essent. Fatty Acids 61: 275–287.   2647–2657.
Abel-Caines, S. F., Grant, R. J., Klopfenstein, T. J., Winowiski,     Mashek, D. G., Bertics, S. J. and Grummer, R. R. 2002.
T. and Barney, N. 1998. Influence of nonenzymatically browned         Metabolic fate on long-chain unsaturated fatty acids and their
soybeans on ruminal fermentation and lactational performance of       effects on palmitic acid metabolism and glucogeneogenesis in
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