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increase milk yield as well and so do not change the butterfat content. In general, when the cow’s acidosis is controlled and energy requirements are supplied with a mix of fibre, starch and fat, no deficiency in long-chain fatty acids will occur to depress butterfat production. Fibre digestion and acetic acid production is reduced in acidic rumens. When converting carbohydrate to energy the rumen microbes produce acids. Rumen acids are buffered primarily with saliva and fibre stimulates saliva production.
Rumen acids are absorbed from the rumen via the finger-like projections on the rumen wall, called papillae. Forage (long fibre) stimulates the movement of rumen contents to increase the absorption of acid through the rumen papillae.
TIPS TO AVOID RUMEN ACIDOSIS: Gradually increase concentrate before and after calving
Don’t exceed 40% non fibre concentrate Avoid too much digestible starch and sugar Feed hay prior to concentrate
Forage NDF should be more than 19% of the diet Have forage or TMR available to cows 24 hours of the day Limit heat stress
SIGNS OF ACIDOSIS: Daily roller-coaster intake and milk production
Inconsistent manure Lack of cud-chewing General cow depression
There are other influences on butterfat production. Magnesium oxide has an additive effect on butterfat when fed with sodium bicarbonate although the exact mechanism is not totally understood. Genetics can greatly impact the fat content of the milk as discussed at the beginning. Stage of lactation can influence butterfat. In early lactation cows that are using a significant amount of their body stores for energy may have an elevated butterfat, although this is likely to have a negative impact on fertility later. Otherwise the percentage butterfat usually decreases with peak milk and increases as milk production declines after peak. Season has an effect as butterfat often declines in the summer months due to heat stress. Similar effects occur with milk protein. More than 90% of the proteins in milk are made in the udder from amino acids, glucose, and acetate. Changes in the ration which increase the supply of glucose to the udder will increase the amount of lactose made,
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