Supplying Energy Needs of the Dairy Cow through Fat Supplementation
Energy for the cow is provided from the breakdown of starch and carbohydrate material in the rumen to produce volatile fatty acids. In addition, fatty acids supplied from dietary fats are also utilized as energy sources. Energy is required for all the processes including maintenance, milk production and replenishment of body reserves. At the time the cow calves, significant hormonal changes occur which have an effect of depressing feed intake. As a result, cows enter negative energy balance and start breaking down body reserves to maintain milk production. This negative energy balance and resulting weight loss is a factor that adversely affects subsequent peak milk yield performance and reproductive performance. A solution for increasing energy density is by feeding fat which has 2.5 times the caloric density of proteins and carbohydrates. Fats however cannot simply be supplemented into the cows diets because they interfere with the fermentation balance in the rumen. Natural fats in the form of triglycerides are hydrolyzed by rumen microorganisms and this can have a deleterious effect on rumen fermentation. In order to supplement fats to the dairy cow, the fats must be in such a form that they do not interfere with fermentation in the rumen and yet are highly digestible and rapidly absorbed and utilized in the small intestine. Research over the last 20 years by Milk Specialties Company has resulted in an understanding that saturated fats that are in the correct physical form will supply very high levels of digestible energy without interfering with rumen fermentation. Other commercial attempts to make fat supplements for ruminant animals include combining calcium with unsaturated fats to produce calcium salts. When selecting a fat source, it is important to understand the ratio of saturated fatty acids and the energy level of the product. Trials have shown that there is a significant reduction in cow body temperature during periods of heat stress when diets have fat added. This results in increased dry matter intake in the cows and greater milk yield and greater milk fat and milk protein production. Dietary fat does not have a heat of fermentation associated with its metabolism in the animals. Research trials have also shown that feeding fat for a 21 day period prior to cows calving has a significant impact on subsequent reproductive performance by priming the cows. Data show less date open and less conceptions and a higher pregnancy rate.
Trevor Tomkins
Milk Specialties Global, IL, USA
国际会议
奶牛营养与牛奶质量国际研讨会(ist International Symposium on Dairy Cow Nutrition and Milk Quality)
北京
英文
108-111
2009-05-04（万方平台首次上网日期，不代表论文的发表时间）