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Feeding for balanced production is gaining increasing importance as more and more contracts reward higher butterfat and protein content milk. Debby Brown discusses how you can benefit
T
he more I travel round the country visiting different farmers
the more I have become aware that most contracts are heading towards payment benefits for butterfat and protein and not just milk yield. This may be on a kg butterfat and protein payment scheme or on a % butterfat and/or protein. Many producers are on A and B contracts and so the efficiency of milk production becomes more and more important. Butterfat and protein yields are not new, but for many appear to be a differing mind set. Through this article I will discuss my opinions and experiences influencing this, but also the science behind it. However, I must begin by stressing that these are highly heritable traits (butterfat kg H47% and protein kg H51%) and, therefore, bull choice has a big impact on the overall herd results and consistency of butterfat and protein yield. The aim is always to be increasing fat and protein yield
without losing milk yield. Increasing just the fat and protein % while dropping milk yield is easier, but does not increase fat and protein kg yield. I have worked with a number of Jersey herds over the years and they expect their cows to produce the minimum of their bodyweight in kg butterfat and protein in 305 day lactation.
My challenge to some of my Holstein farmers was, therefore, to aim for the same target. The key is to meet the requirements of the rumen correctly, ensuring it is healthy and has balanced nutrients. The result being a more stimulated microbial population, digesting forage better and producing more volatile fatty acids, therefore, energy and microbial protein, therefore, protein.
About 50% of butterfat is made from short-chain fatty acids, specifically acetate and butyrate, produced in the rumen. The rest is
made from long-chain fatty acids coming from dietary fat, microbial bodies and back fat. When high levels of rumen available unsaturated fatty acids are fed and leave the rumen as partially saturated trans fatty acids they can inhibit butterfat synthesis. More of these trans fatty acids escape the rumen when it is acidic when there is a decrease in the rumen acetate:propionate ratio.
Acetate and butyrate are primarily made in the rumen from the fermentation of fibre. Good fibre fermentation is the result of feeding highly digestible forages, controlling rumen pH, controlling the levels of rumen available fats in the ration (<5%), and providing adequate amounts of rumen available nitrogen and amino acids. When in positive energy balance the long-chain fatty acids have to come from the diet and are often given as dietary fat supplementation. These often
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