"Farmnote 3599 Feed Quality and Safety for Dairy Cows"
Feed Quality and Safety for Dairy Cows Farmnote 35/99 [Reviewed November 2005] : Department of Agriculture Feed Quality and Safety for Dairy Cows Farmnote 35/99 By J.R.M. (Ian) Bell and S.J. Gallagher Forage feeds - taints and odours The stability of flavour in milk and dairy products is important, since customers demand a consistent product. This is particularly important in the Asian export market where the slightest change in flavour may be detected and queried. Sources of taints and odours Milk absorbs taints and odours very easily. Most feed taints arise from the absorption by the cow of chemical compounds from feed. These chemical compounds are subsequently imparted to the milk by way of the blood. Waste crops such as orange peel, vegetables such as onion and cabbage and poorly fermented silage also produce feed flavours in milk. Some weeds also produce strong flavours in milk when eaten during grazing. Weeds such as capeweed cause tainting problems at various times of the year. Control of taints q When establishing pastures and crops ensure that weeds are controlled during the establishment period. q If possible, eradicate problem weeds when identified. q If the plants causing the tainting cannot be eradicated, exclude the milking herd from the contaminated area. q When weeds are sprayed, ensure the correct withholding times for grazing are Feed Quality and Safety for Dairy Cows Farmnote 35/99 [Reviewed November 2005] : Department of Agriculture observed. Figure 1. Milking herd on irrigated pasture Chemical residue Chemicals sprayed onto forage crops and pasture can contaminate farm milk. When spraying forage crops or pasture with chemicals, it is important that the correct product, application rate and withholding periods are observed. Concentrate feeds Chemical residues in milk may originate from a number of sources. While the farmer controls many of these sources, it is much harder to control feed bought in from outside the property. Purchasing contaminated grain or concentrates can be very expensive, because pesticide residues are often not detected until it is too late, that is, the residues are already stored in the cows' body fat and are being released into milk. The time taken to clear residues from the cows system depends on how much residue was consumed, level of body fat, stage of lactation and the age of the animal. Avoiding pesticide residues When purchasing concentrate or grain, it is important that a guarantee is obtained that the feed is free from any harmful chemical residue. Further reading q Farmnote 18/99 'Preventing antibiotic residues in milk' q Farmnote 36/99 'Milk cooling and storage' q Farmnote 37/99 'Milking machine operation' q Farmnote 38/99 'Dairy bacterial identification service' Feed Quality and Safety for Dairy Cows Farmnote 35/99 [Reviewed November 2005] : Department of Agriculture q Farmnote 39/99 'Milk filtration' q Farmnote 40/99 'Checking milking plant hygiene' q Farmnote 41/99 'Water quality for dairying' q Farmnote 42/99 'Cleaning and sanitising milking plant' Acknowledgments Procedures partly adopted from NSW Dairy Corporation, Proven Perfect Reference Manual. Important Disclaimer The Chief Executive Officer of the Department of Agriculture and the State of Western Australia accept no liability whatsoever by reason of negligence or otherwise arising from the use or release of this information or any part of it