Effects of Body Measurements and Weight on Calf Size

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					Effects of Body Measurements and Weight on Calf Size
and Calving Difficulty of Holsteins I
                                                    M. SIEBER,2 A. E. FREEMAN? and D. H. KELLEY
                                                                          Animal Science Department
                                                                                Iowa State University
                                                                                        Ames 50011

                   ABSTRACT                                             INTRODUCTION

      Body measurements (heart and paunch                   Dystocia is an important problem of dairy
  girths, wither height, chest depth, pelvic            cattle. In 1976, Philipsson (17, 18 19) re-
  length and width, and body length), body              searched calving difficulty, stillbirth, and asso-
  weight, and calving evaluation data (calf             ciated factors and related body measurements
  birth weight, calf sex, calf presentation,            to dystocia for Swedish dairy cattle breeds. At
  and calving assistance needed) were col-              the same time, Pollak and Freeman (20) were
  lected from 1974 parities of 762 Holstein             conducting the first large research study of
  cows between 1968 and 1986. Degree of                 dystocia for US dairy cattle. Djemali et al. (10)
  calving assistance was scored continu-                reported an additional 14 d open and 465 kg
  ously from 1 (no assistance) to 10 (hard              less milk for cows with extreme calving diffi-
  mechanical assistance). Phenotypic corre-             culty than for cows with no calving difficulty.
  lations of dam body traits with calf birth            McDaniel (13) demonstrated decreased milk
  weight were all significantly positive                yield in the lactation following a difficult birth
  when combined for all parities and                    and estimated in 1981 that minimum cost for
                                                        each assisted birth was $50 to $60 for heifers.
  ranged from .23 for paunch girth to .27
                                                            Dystocia is affected by several nongenetic
  for body weight and heart girth. Correla-
                                                        and genetic factors, including age and parity of
  tions of dam body traits with calving
                                                        dam (2, 7, 8, 12, 17, 20), sex of calf (4, 7, 8, 12
  assistance scores were all significantly
                                                        ,20), year-season (8, 18, 20), size of calf (20),
  negative across parities and ranged from
                                                        and evaiuator of birth difficulty (11). Pheno-
  -.24 to -.30. Correlations of calf birth              typic correlations between calving difficulty
  weight with calving assistance were                   and calf birth weight range from. 17 to .54 (3, 7
  higher for first parity (.37) than for all            ,21). Most studies (2, 4, 8, 20, 24, 25, 26) have
  parities (.20). Least squares analysis                found low heritability (approximately t 0%) for
   showed that cows with shorter wither                 calving difficulty.
   height and shorter pelvises tended to re-                Differences among dairy bulls have been
  quire more calving assistance. Heavier                reported if dystocia is measured as a direct
  calves, winter calvings, and earlier parity           effect of the sire (4, 6, 20). For beef breeds,
  all were related to increased dystocia.                some researchers have shown significant sire
   Male calves were heavier than female                 differences (8, 26). However, Sagebiel et al.
   calves and also were associated with                  (22) found that sire effects within breeds were
   greater calving difficulty.                           not significant for beef breeds; they reported
                                                         that sire and cow breeds had significant effects
                                                         on dystocia scores if the calf was male. Thomp-
                                                         son et al. (24) found no relationship between
                                                         sire transmitting ability for production and dys-
    ReceivedSeptember16, 1988.
    AcceptedFebruary27, 1989.                            tocia but a negative correlation (-.28) between
    1journal Paper Number J-12933, Iowa Agriculture and transmitting ability for type and dystocia. They
HomeEconomicsExperimentStation, Ames; ProjectNum- also found that size of the cow had a major
ber 1053.                                                effect on the type-dystocia relationship; for
    2present address: Animal ImprovementProgramsLabo-
rato_ry,ARS, USDA,Beltsville,MD 20705.                   daughters, large size was associated with both
    3Reprintrequests.                                    high type scores and increased dystocia, Ali et

1989 J Dairy Sci 72:2402-2410                     2402
                         BODY MEASUREMENTS AND CALVING DIFFICULTY                                   2403

al. (1), however, found that daughters that were     or posterior), and calving assistance needed
large with wide pins, long sloping rumps, and        (type and degree). Calving assistance needed
little slope from thurl to pin bone were more        was classed as none, manual, manual with ob-
likely to have easier calvings. Boldman and          stetrical chains, or mechanical; difficulty of
Famula (6) studied relationship of sire transmit-    calving was evaluated by an observer as easy,
ting ability for dystocia with progeny linear        intermediate, or hard for each calving assis-
type traits. They reported little correlated re-     tance class. Only three caesareans and three
sponse in linear type traits among bulls whose       embryotomies occurred; these were excluded
progeny were born with the least difficulty.         from analyses. Of 33 twin births (66 calves),
     Since 1978, the National Association of Ani-    none were assisted mechanically. Distribution
mal Breeders has evaluated Holstein sires na-        of calving assistance scores was similar to that
tionally for dystocia. The original linear proce-    for nontwin births. A preliminary analysis
dure of Berger and Freeman (4) was modified          showed that differences in calf birth weight
to a categorical method for July 1988 evalua-        between twins and nontwins was slight; there-
tions (9). The goal of this program is to identify   fore, twin births were not excluded from analy-
sires that might be preferred for mating to          ses. Only records without an abortion were
heifers and small cows because less assistance       included. Each evaluator scored more than 30
is needed during birth of these sire's progeny.
     The objectives of this study were to deter-         Body measurement and weight data were
mine 1) relationships between cow body mea-
                                                     combined with calving evaluation data. All
surements and weight with calf birth weight
                                                     fifth and greater parities were grouped together.
and 2) relationships of cow body measurements
                                                     The final data included 1794 parities from 762
with calving difficulty by parity.
                                                        The model for analyzing calf weight was:

   Body measurement and body weight data                 Yijklmo = kt + (YS)i + Pj + gk + Vl
were obtained from the Iowa State University                                     8
research herd at Ankeny. Seven body measure-                           +sin + Z       bn(mijklmno- ~ n )
ments (heart girth, paunch girth, wither height,                               n= l
chest depth, pelvic length, pelvic width, and                             + eijklmo                  [1]
body length) and body weight were recorded
between 30 and 55 d postpartum. Data were
collected between 1968 and 1986 as described         where:
by Sieber et al. (23).
   The Ankeny research farm is operated under            Yijklmo = calf birth weight measured by
typical to above average Iowa conditions and is                     evaluator 1 for calf o of sex m
used primarily for long-term dairy cattle breed-                    born in year-season i from par-
ing research. In this herd, foundation females                      ity j of a cow resulting from
were selected for low and high milk yield based                     mating to a sire in sire group k;
on pedigree estimates and were mated to sires                  kt = overall mean;
selected for high and breed average PD milk in              (ys)i = effect of year-season i (within
a 2 x 2 factorial design. Based on average PD                       year, season 1 = May through
milk of active AI sires each year, progeny of                       October and season 2 = No-
high PD sires are mated to high PD simms, and                       vember through April);
progeny of average PD sires are mated to aver-                 pj = effect of parity j (j =
age PD sires for all generations. This breeding                      1,2,3,4,>5);
strategy causes the genetic difference between                gk = effect of sire group k [k = I
the two cow populations to approach the differ-                     (high PD), 2 (breed average
ence in breeding value (twice their difference in                      PD)];
PD) between the two sire groups after several                   Vl = effect of calving weight evalua-
generations.                                                         tor 1 (1 = 1..... 5);
   Calving evaluation data were calf birth                     Sm = effect of calf sex m [m = 1
weight, sex of calf, calf presentation (anterior                     (male), 2 (female)];

                                                              Journal of Dairy Science Vol. 72, No. 9, 1989
2404                                            SIEBER El" AL.

  mijklmno = cow body measurement for                   TABLE 1. Overall distribution of records across all parities
              trait n (n = 1..... 8);                   by type and degree of calving assistance (number of re-
                                                        cords = 179~,).
        Nn = mean for body measurement
              trait n for all cows;                         Calving assistance
         bn = regression coefficient for body           Type          Degree           Score Number Percentage
              measurement trait n; and                  None                            1     1222     68.1
    eijklmo = random residual.                          Manual        Easy              2       54      3.0
                                                                      Intermediate      3       15       .8
All effects except residual were fixed. A cow                         Hard              4        1       ,1
effect was not included in the model even               Manual with Easy                5       99      5.5
though cows produced more than one calf. If             obstetrical Intermediate        6      217     12.1
                                                        chains      Hard                7      147      8.2
the data were perfectly balanced, all cow ef-
                                                        Mechanical    Easy               8       2        .1
fects would be in the residual; lacking balance,                      Intermediate       9      15        .8
some cow effects might be included in other                           Hard              10      22       1.2
effects in the model. Cows can be considered as
random variables; thus, the expected effects on
other variables in the model are zero if there is
no selection on cows across parities for the                The model for analyzing difficulty was:
traits of interest or correlated traits. Voluntary
culling before 1977 was extremely limited (5);
                                                                 Yijldmo = I.t + (ys) i + Pj + gk
therefore, no selection on cows relative to the
traits analyzed or to correlated traits was as-                              +v 1 +s m
sumed. Residual variance would be larger with                                   8
some cow effect included, and tests of signifi-                              + ~       bn(mijklmno-Nn)
cance are conservative. Data were analyzed
across parities. Submodels that included fewer                               + bw:~'ffijklmo - w---)
than eight covariables were not investigated.                                + eijklmo                  [2]
    Calving assistance data were assigned scores
based on the degree of actual assistance given           where:
 (Table 1). The descriptions related to how as-
 sistance was given so that assistance could be                Yijklmo = calving assistance score for
recorded more objectively. Three herdsman did                            dam of calf o;
 all the evaluations and assigned scores as de-                Wijklmo = fixed effect of birth weight of
 scribed. Obstetrical chains were always avail-                          calf o;
 able, and if they were used, the degree of                            = mean birth weight of all calves;
 assistance needed was generally greater than if                    bw = regression coefficient for birth
 assistance was manual. Scores ranged from 1                             weight of calves;
 (no assistance) to 10 (hard mechanical assis-
 tance). Scores could have been assigned based           and all other effects are as in Model [1 ]. As
 on frequency, but this was not done for this            with Model [I], Model [2] was used for analy-
 analysis. Even if scores 4 (hard manual assis-          sis on an overall parity basis.
 tance) and 5 (easy manual assistance with ob-              Quadratic effects of body measurements and
 stetrical chains) had been reversed, the conclu-        weight were not significant under either model
                                                         and, therefore, were not included in final analy-
 sions would have been the same. No
 misclassification occurred at the ends of the
 range of scores. Analyses of calving difficulty
 (as assistance was actually given) were con-                        RESULTS AND DISCUSSION
 ducted with the assumption of continuity for               Means and SD of dam body measurements
 calving assistance scores, similar to the method        and weights and calf birth weights are in Table
 used by Meyer and Burnside (16) for subjective          2 by and across parities. All body traits and calf
 milking speed scores.                                   weight increased with parity. Pelvic length and

Journal of Dairy Science Vol. 72, No. 9, 1989
                            BODY MEASUREMENTS AND CALVING DIFFICULTY                                          2405
TABLE 2. Means and SD for dam body lxaits (measurements and weights) and calf birth weights by and across parities.
Trait                       1              2             3               4            ->5           All
Number of calves            739            442           294             169           150          1794

Heart girth, cm             187.5          195.6          201A           202.8         205.2        194.6
Paunch girth, cm            219.9          232.0         238.6            241.9         245.4       230.1
Wither height, cm           131.1          135.5         137.0            137.3        138.3        134.3
Chest depth, cm              71.7            74.8         76.7            77.4          78.2         74.4
Pelvic length, cm            51.9            54.2         55.3              55.5         55.6          53.7
Pelvic width, cm             51.1           54.9          56.9             57.5         58.1         54.1
Body length, cm             153.2           159.5        163.2           163.8         164.2        158.3
Body weight, kg             489.4          553.1         595.2            610.7        629.7        545.6
Calf weight, kg              37.9           39.7          41.1              41.1        41.6         39.5
Heart girth, cm               7.3               6.7           7.8           7.8          7.4           9.8
Paunch girth, cm             10.1              10.0           10.8           10.7       10.8         13.9
Wither height, cm             3.6               3.6            3.8          3.8          4.0          4.7
Chest depth, cm               2.6               2.4           2.6           2.5          2.6          3.5
Pelvic length, cm             2.2               2.1           2.4           2.5          2.3          2.7
Pelvic width, cm              2.4               2.3            2.5          2.4          2.5          3.7
Body length, cm               5.7               5.9           6.0           5.8          5.4          7.4
Body weight, kg              49.4              53.2          60.8          59.3         62.1         75.3
Calf weight, kg               4.4                5.8            5.3            6.2       5.4          5.8

width, chest depth, and wither height had                    but were significant only for body weight
smaller SD than did other body traits.                       (P<.01) and heart and paunch girths and wither
   Distribution of calvings by calving difficulty            height (P<.05). No traits had significant
is in Table 3 by parity. For first parity, over              (P<.05) correlations for third parity. For fourth
50% of births received some degree of assis-                 parity, correlation for pelvic length was slightly
tance. As parity increased, percentage of cows               significant (P<.05) and positive (.t6). For fifth
receiving assistance decreased: 52% dystocia                 parity and greater, correlations for body length
for first parity, 20% for second, 17% for third              and weight were significant (P<_.05) and posi-
and fourth, and 14% for fifth and greater. As                tive (.20). Across all individual parities, all
reported by Bar-Anan et al. (2), dystocia was                correlations were highly significant (P<.001)
two to three times greater at first calving than             and positive. Correlations across parity ranged
at later calvings. Philipsson (17) found similar             from .23 for paunch girth to .27 for heart girth
results with 15.7% dystocia for heifers versus               and body weight. In general, calves from
4.8% for cows. In a more recent study with a                 heavier and larger cows were heavier than those
large number of Holstein records, Djemali et al.             of smaller and lighter cows.
(10) found 28 to 36% dystocia for first-calf                     Phenotypic correlations of dam body traits
heifers and I0 to 16% dystocia for older cows.               and calf birth weight with calving assistance
   Phenotypic correlations computed as Pear-                 are in Table 5 by and across individual parities.
son product-moment correlations of dam body                  For individual parities, none of the dam body
measurements and weights with calf birth                     measurements had significant (P<.05) correla-
weights are in Table 4 by and across individual              tions. Correlation of dam body weight with
parities. For first parity, all dam body traits had          calving assistance score was significant (P___.05)
positive, highly significant (P<.001) correla-               and positive (.18) for fourth parity. Across all
tions with calf birth weight except for paunch               individual parities, however, correlations for
girth, which was less significant (P<.01). Cor-              dam body traits were all highly significant
relations were lowest (.10) for paunch girth and             (P<.001) and negative; correlations ranged
highest (.21) for heart girth and chest depth.               from - . 2 4 (heart and paunch girths, body
For second parity, all correlations were positive            length, and body weight) to - . 3 0 (pelvic width).

                                                                      Journal of Dairy Science Vol. 72, No. 9, 1989
2406                                                     SlEBER ET AL.

TABLE 3. Distribution of records by type of calving assistance and parity.
                                      1                   2                  3                   4            >5         All
CMves                                 739                  442                   294              169         150         1794
Type of cMving assistance
 None                                 357                 353                243                  140         129         1222
 Manu~                                 29                  15                 14                    8            4          70
 Manu~ with obstetric~ chains         317                  73                37                    20          16          463
 Mechanical                            36                   1                   0                     1             1       39
Type of calving assistance
 None                                     48.3                79.9               82.7                82.8         86.0         68.1
 Manual                                    3.9                 3.4                4.8                 4.7          2.7          3.9
 Manual with obstetrical chains           42.9                16.5               12.6                11.8         10.7         25.8
 Mechanical                                4.9                  .2                0                    .6           .7          2.2

Correlations became significant across all pari-                         ties are in Table 6. All regression coefficients
ties because of the general increase in body size                        for dam body measurements and weight gener-
as a cow aged, which increased the range of                              ally were small and nonsignificant (P<.05), Al-
measurements. In general, heavier and larger                             though many phenotypic correlations in Table 4
cows had easier calvings and needed less assis-                          were significant, they had not been adjusted for
tance than did smaller cows. Correlations of                             other effects, which explains why correspond-
calf birth weight with calving assistance were                           ing regression coefficients in Table 6 were
highly significant (P<.001) and positive regard-                         nonsignificant. Average LS means for summer
less o f parity and ranged from .20 to .39.                              and winter seasons were significantly (P_<.001)
BreDahl (7) found similar correlations between                           different with calves .60 kg heavier for winter
birth weight and calving assistance o f . 17 to .27                      than for summer calvings. Parity did not have a
for four breeds as did Rice and Wiltbank (21)                            significant (P<.05) effect on calf birth weight.
for Angus (.36) and Herefords (.44).                                     Significant (P_<.05) difference was found be-
    Results from least squares (LS) analysis of                          tween sire groups; calves from high PD bulls
Model [1] for calf birth weight across all pari-                         were .64 kg heavier than those from breed-av-

TABLE 4. Phenotypic correlations1 of dam body traits (measurements and weights) with calf birth weights by and across
individual parities.
Trait                        1               2                       3                    4                 >-5          All
Heart girth                  .21"**              .10"                  .04                 .I1              .13          .27***
Paunch girth                 .10"*               .12"                  .02                 .08              A0           .23***
Wither height                .20***              .10"                  .04                  .06             .11          .25***
Chest depth                  .21"**              .02                 -.01                  .05              .06          .24***
Pelvic length                .18'**              .08                   .04                 .16"             .07          .24***
Pelvic width                 .16"**              .07                   .03                 .11              .14          .26***
Body length                  .15"**              .08                   .01                 .13               .20*          .24***
Body weight                  .18"**              .15"*                 .05                 .11              .20*         .27***
    1pearson product-moment correlation.

Journal of Dairy Science Vol. 72, No. 9, 1989
                              BODY MEASUREMENTS AND CALVING DIFFICULTY                                                         2407
TABLE 5. Phenotypic correlations 1 of dam body traits (measurements and weights) and calf birth weights with calving
assistance by and across individual parities.
Trait                          1                   2                3                4               _>5            All
Heart girth                     .05                -.06               .00             .12           -.16            -.24"**
Paunch girth                    .02                  .01            -.05             .14            -.I0            -.24"**
Wither height                 -.02                 -.04             -.05             .02            -.07            -.25***
Chest depth                     .01                -.08              -.08            .01            -.10            -.27***
Pelvic length                 -.04                  -.06              -.08           .11            -. 15           -.25***
Pelvic width                  -.03                 -.05             -.04             .11            -.01            -.30***
Body length                   -.01                   .01            -.03             .02            -.10            -.24***
Body weight                     .05                -.01              -.01            .18"           -.14            -.24***
Calf weight                     .37***               •25***            •38***        •39***           .29***          •20***
    1Pearson product-moment correlation.

erage bulls. D i f f e r e n c e s a m o n g evaluators also            at birth. E f f e c t o f calf sex on calf birth w e i g h t
were significant (P<.01). Largest significant                           agrees with results o f Philipsson (19), w h o
(P_.001) difference was for calf sex; m a l e s                         f o u n d that m a l e calves usually had larger b o d y
calves w e i g h e d 2.1 kg more than f e m a l e calves                d i m e n s i o n s than did females, and M e i j e r i n g

TABLE 6. Least squares (LS) analysis of calf birth weight on dam body traits (measurements and weight) over all parities
(number of records = 1794).
Source                             df                    coefficient            MS              LS X               LS SE
Heart girth                              1                    .05                45.95
Paunch girth                             1               ~,04                    65.73
Wither height                            1                 .08                   82.61
Chest depth                              1               -.05                     9.79
Pelvic length                            1               -.01                       .50
Pelvic width                             1                 .03                    2.99
Body length                              1                 .04                   46.32
Body weight                              1                 .01                   89.57
Year-season                             29                                       99.24***
 Summer                                                                                          39.26             :8"1
 Winter                                                                                          39.83             .82
Parity                                                                           "37.98
Sire group                               1                                       174.66"
 High                                                                                            9.87              32"
 Average                                                                                         39.23             .32
Evaluator                                                                        110.35"*
Calf sex                                                                        1897.13"**
 Male                                                                                            id./o             132
 Female                                                                                          38.51             .32
Residual                            1746                                         27.33
R2                                           .20

                                                                                  Journal of Dairy Science Vol, 72, No, 9, 1989
2408                                              SIEBER ET AL.

TABLE 7. Least squares (LS) analysis of calving assistance score on dam body traits (measurements and weight) and calf
birth weight over all parities (number of records = 1794).

Source                           df               coefficient        MS             LS ~             LS SE
                                                                                                 (score I)
Heart girth                            1            .01                 .95
Paunch girth                           1            .00                 .34
Wither height                          1          -.04"               19.72
Chest depth                            1            .03                2.64
Pelvic length                          1          -.12"**             51.90"**
Pelvic width                           1          -.03                 3.18
Body length                            1            .02                6.62
Body weight                            1            .00                 .42
Calf birth weight                      1           .13"**            793.78***
Year-season                           29                               7.07*
 Summer                                                                             i.;9             .33
 Winter                                                                             2•10             .33
Parity                                                               167.95"**
   2                                                                                1.75             .14
   3                                                                                1.43             .17
  4                                                                                 1.41             .21
 ->5                                                                                1.35             .22
Sire group                                                           • "9155
Evaluator                                                              12.62*
Calf sex                                                              46.54**
 Male                                                                               i.io             113
 Female                                                                             1.73             ,13
Residual                          1745                                 4.42
R2                                         .30
   lCalving assistance score coded 1 (no assistance) to 10 (hard mechanical assistance).

(14), who reported that male calves were 1 to 3                 sociated with greater calving difficulty. Differ-
kg heavier than females at birth.                               ence between average LS means for summer
   Results from LS analysis of Model [2] for                    and winter seasons was significant (P_<.05) with
calving assistance score across all parities are                less calving difficulty associated with summer
in Table 7. Wither height had a small negative                  than winter calving. Pollak and Freeman (20)
coefficient (-.04, P<.05), which indicates that                 found similar results and reported that winter
shorter cows have more calving problems than                    births (October to March) were more difficult
do taller cows• The coefficient for pelvic length               than summer births. Parity had a highly signifi-
had a higher level of significance (P<_.001) and                cant (P<.001) effect on calving assistance score
was larger in magnitude (-.12). Cows with                       with more assistance needed for first parity
shorter pelvises had more difficulty giving birth               than for later parities. This result agrees with
and needed more assistance than did cows with                   findings of previous studies (2, 15, 17, 20)• No
longer pelvises. Philipsson (19) and Menissier                  significant (P<.05) difference was found be-
et al. (15) have reported that dystocia seems to                tween sire groups, but differences between
be caused mainly by feto-pelvic incompatibili-                  evaluators were significant (/'<.05). A signifi-
ty. Regression coefficients for calf birth weight               cant (P<.01) difference was found between
were highly significant (P<.001) and positive.                  male and female calves in their effect on dam's
As expected, heavier calves generally were as-                  need for calving assistance; dystocia was asso-

Journal of Dairy Science Vol• 72, No. 9, 1989
                              BODY MEASUREMENTS AND CALVING DIFFICULTY                                                  2409

ciated more often with births o f male calves                   cultural Research and            Development         Project
than with those o f females as reported in pre-                 N u m b e r 1-629-83-RE.
vious studies (2, 4, 19, 20). In a separate analy-
sis a n d after correction for differences in birth                                  REFERENCES
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    Data from the Iowa State University breed-                    6 Boldman, K. G., and T. R. Famula. 1985. Association of
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ing research herd showed that 52% o f first                         traits in Holsteins. L Dairy Sci. 68:2052.
parity cows received assistance in calving. As                    7 BreDahl, R. L. 1970. Beef-dairy cow breeding: a study of
c o w ' s parity increased, dystocia percentage de-                 birth traits. Ph.D. Thesis, Iowa State Univ., Ames, Univ.
creased. P h e n o t y p i c correlations b e t w e e n d a m       Microfilm No. 71-14207.
                                                                  8 Brinks, J. S., J. E. Olson, and E. J. Carroll. 1973. Calving
body traits and calving assistance indicated that
                                                                    difficulty and its association with subsequent productiv-
heavier and larger cows generally had easier                        ity in Herefords. J. Anim. Sci. 36:111.
calvings and needed less assistance than did                      9 Djemali, M., P. J. Berger, and A. E. Freeman. 1987.
smaller cows. However, only a few body mea-                          Ordered categorical sire evaluation for dystocia in
surements of the dam were useful in predicting                       Holsteins. J. Dairy Sci. 70:2374.
                                                                 10 Djemali, M., A. E. Freeman, and P. J. Berger. 1987.
calving difficulty. Cows with short pelvises                        Reporting of dystocia scores and effects of dystocia on
were especially likely to need more assistance                       production, days open, and days dry from Dairy Herd
at birth than were cows with long pelvises.                          Improvement data. J. Dairy Sci. 70:2127.
Birth weights were heavier for male calves a n d                 11 Freeman, A. E. 1984. Secondary traits: sire evaluation
winter calvings than for female calves and sum-                      and the reproductive complex. J. Dairy Sci. 67:449.
                                                                 12 Laster, D. B., H. A. Glimp, L. V. Cundiff, and K. E.
mer calvings. Short pelvises, winter calvings,                       Gregory. 1973. Factors affecting dystocia and the effects
first parity, heavy calf birth weights, and male                     of dystocia on subsequent reproduction in beef cattle. J.
calves were associated with greater calving dif-                     Anim. Sci. 36:695.
ficulty than were normal pelvises, s u m m e r                   13 McDaniel, B. T. 1981. Economic impact on calving
                                                                     difficulty in Holstein heifers. J. Dairy Sci. 64(Suppl.
calvings, later parities, normal calf birth
                                                                     1):82. (Abstr.)
weights, and female calves.                                      14 Meijering, A. 1984. Dystocia and stillbirth in cattle-a
                                                                     review of causes, relations and implications. Livest.
                 ACKNOWLEDGMENTS                                     Prod. Sci. 11:143.
                                                                 15 Menissier, F., J. L. Foulley, and W. A. Pattie. 1981. The
    Financial scholarship support from the                           calving ability of the Charolais breed in France, and its
                                                                     possibilities ibr genetic improvement. I. The importance
Deutsche Forschungsgemeinschaft, Bonn, W e s t                       and causes of calving difficulties. Ir. Vet. J. 35:73.
G e r m a n y , and scholarship program coordina-                16 Meyer, K., and 13. B. Burnside. 1987. Scope for a
tion and project interest of E. Kalm, University                     subjective assessment of milking speed. J. Dairy Sci.
of Kiel, is acknowledged gratefully. Apprecia-                       70:1061.
tion is expressed to M. Healey for computa-                      17 Philipsson, J. 1976. Studies on calving difficulty,
                                                                     stillbirth and associated factors in Swedish cattle breeds.
tional assistance and to S. M. H u b b a r d for                     I. General introduction and breed averages. Acta Agric.
manuscript improvement. This research was                            Scand. 26:151.
supported in part by US-Israel Binational Agri-                  18Philipsson, J. 1976. Studies on calving difficulty,

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2410                                                   SIEBER ET AL.

    stillbirth and associated factors in Swedish cattle breeds.      reciprocally crossed Angus, Hereford and Charolais
    II. Effects on nongenetic factors. Acta Agric. Scand.            cattle. J. Anim. Sci. 29:245.
    26:165.                                                       23 Sieber, M., A. E. Freeman, and D. H. Kelley. 1988.
 19Philipsson, J. 1976. Studies on calving difficulty,               Relationships between body measurements, body
    stillbirth and associated factors in Swedish cattle breeds.      weight, and productivity in Holstein dairy cows. J. Dairy
    IV. Relationship between calving performance, precalv-           Sci. 71:3437.
    ing body measurements and size of pelvic opening in           24 Thompson, J. R., A. E. Freeman, and P. L Berger. 1980.
    Friesian heifers. Acta Agric. Scand. 26:221.                     Relationship of dystocia transmitting ability with type
 20 Pollak, E. J., and A. E. Freeman. 1976. Parameter                and production transmitting ability in Holstein bulls. J.
    estimation and sire evaluation for dystocia and calf size        Dairy Sci. 63:1462.
    in Holsteins. J. Dairy Sci. 59:1817.                          25 Thompson, J. R., A. E. Freeman, and P. J. Berger. 1981.
 21 Rice, L. E., and J. N. Wiltbank. 1970. Dystocia in beef          Age of dam and maternal effects for dystocia in Hol-
    cattle. J. Anim. Sci. 30:I043.                                   steins. J. Dairy Sci. 64:1603.
 22 Sagebiel, J. A., G. F. Krause, B. Sibbit, L. Lanford, J. E.   26 Willham, R. L. 1970. Variation in calving scores given
    Comfort, A. J. Dyer, and J. F. Lasley. 1969. Dystocia in         Charolais cows. J. Anim. Sci. 31:171.

Journal of Dairy Science Vol. 72, No. 9, 1989