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0808 PD: Nutritional strategies = More milk components, more money

John Hibma Published on 19 May 2008

Milk pricing for most dairy farmers in the U.S. is based on the pounds of milk components shipped.

With milk prices at all-time highs, it makes sense to get your cows to produce as many pounds of milk solids – principally butterfat and protein – as possible.

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Even though colored breeds have higher percentages of milk components than the dominant Holstein breed, within each breed, nutrition and nutritional efficiency will have a significant influence on the total pounds of milk fat and milk protein a cow produces. To maximize milk revenue we must maximize the total pounds of milk components in the milk – and not necessarily the gallons of milk produced by a cow. Improving and maintaining milk components is highly dependent upon a well-balanced diet as well as forage quality.

It’s all about the rumen
A healthy, efficiently functioning rumen is the foundation of every dairy cow’s milk production. When the rumen is working properly – making bugs and fermenting feed – the cow will respond by producing more milk and milk components. And the foundation of a healthy rumen is a consistent supply and balance of rumen microbes.

Within the rumen environment, bacteria and other organisms ferment feedstuffs eaten by a cow. Some of those microbes work specifically on fibrous feedstuffs while others work only on starches and sugars.

It has been well documented for many years that milk fat synthesis is influenced largely by fiber fermentation. Short-chain fatty acids, primarily acetate and butyrate, are the precursors to milk fat production and are produced by fermentation of fiber. The better the forage solubility in a cow’s diet, the better the fiber fermentation will be, resulting in more acetate and butyrate.

Milk protein is synthesized primarily from amino acids in the bloodstream. However, the specific balance of those amino acids is crucial to that synthesis. If a particular amino acid is in short supply, milk protein synthesis will be limited. Amino acid absorption into the bloodstream is dependent upon both microbial protein exiting in the rumen and bypass protein coming directly from the cow’s diet.

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It’s a balance of carbohydrates and protein
The key to achieving maximum rumen efficiency is matching carbohydrate sources with protein sources. All feedstuffs have varying levels of solubility and rates of degradation. Some carbohydrates, such as sugar, degrade very rapidly in the rumen, as does non-protein-nitrogen such as urea. The microbes need a consistent supply of both nitrogen and carbohydrates to maintain their life cycles as well as complete fermentation of feedstuffs. A fast-degrading starch with a fast-degrading protein will keep rumen microbes in top form. But if you have a fast starch and a slowly degraded protein (for example, a finely ground corn meal and an overcooked distillers grain) the necessary nutrition for the microbes will be out of synch and fermentation will suffer.

Forage digestibility
Improving forage digestibility will improve milk fat synthesis. But fiber in the rumen also plays an important role in slowing down the rate-of-passage of feedstuffs so the bugs have time to do their work, so forages in a feed ration have to be digestible – but not too good. We’ve all seen what happens to milk fat tests (and manure) when cows are abruptly turned out onto a lush, green pasture in the spring time.

Forage quality and solubility must also be matched to the protein and carbohydrate solubility so as not to upset the microbe balance.

Putting it all together
The corn silage crop in New England for 2007 was one of the best in recent memory. Fiber (NDF) digestibility analysis for many fields was significantly better than previous years. Grain production was also very high, resulting in good starch numbers. This has resulted in butterfat percentages being up by two or three points in many herds with milk production remaining at about the same level. (Fat-corrected milk has increased.) With or without the improved forage quality, we always make it a point to balance nitrogen and carbohydrate fractions in our rations as best we can. The improved forage quality this year has been icing on the cake, adding nicely to the dairy’s milk-blend price.

Improving milk protein continues to be a challenge. A lot of work is still needed in determining the amino acid requirements of the rumen microbes and what percentage of those amino acids are absorbed in the small intestine. In the meantime, we do understand that the more efficiently the rumen operates, the more microbial protein that’s produced. The way we get that efficiency is by, again, focusing on digestible forages, providing a proper balance of soluble and bypass dietary proteins, synchronizing carbohydrate and protein intakes, maximizing dry matter intakes (DMI) and keeping rumen pH fluctuations to a minimum. Dairy farmers who can do that will quite often see an improvement in total milk protein – again adding value to the milk they produce.

Research into improving rumen nitrogen efficiency, milk production and increasing milk components continues to make progress each year. Dairy farmers have to make the decision from one year to another, and sometimes one season to another, as to whether it’s cost-effective to maximize milk components based upon milk prices and feed prices. Even with the higher feed prices in 2008, milk prices certainly justify dairy farmers to make the most of increased milk components. PD

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John Hibma for Progressive Dairyman

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