Nutrition and Reproduction in Modern Dairy Cows
نویسنده
چکیده
Genetic improvement programs have done a great job selecting animals with superior genetics for milk production. Selection with emphasis on milk production is generally recognized as the single most important objective of breeding programs in dairy cattle worldwide. As a result of this improvement, the dairy cow has changed significantly over the past 7 decades with a remarkable increase in milk production/lactation (Butler, 2000). Comparing the shape of lactation curves from a dairy cow from the 1940s with today’s dairy cow, it is evident that the milk yield/lactation is almost 5 fold higher than in the 1940s. However, comparing reproductive performance, the modern dairy cow has decreased fertility (Butler, 2000) which has become the number one reason for involuntary culling (NAMHS, 2007).
منابع مشابه
Physiological Mechanisms Linking Reproduction to Nutrition in High-Producing Dairy Cows
Dairy cattle are inseminated and pregnancy is established during lactation. Therefore, lactation and the reestablishment of pregnancy must overlap. Unfortunately, recent changes in the genetics, productivity, and management of dairy cows have led to a decline in reproductive efficiency. Reproductive decline in dairy cows began in the mid-1980’s and may be continuing on modern dairy farms (Lucy,...
متن کاملEffect of Feeding Quickly Degradable Nitrogen on the Development of Ovarian Follicles in Lactating Dairy Cows
The objective of this study was to examine the effect of an excess intake of quickly degradable nitrogen (QDN) on ovarian follicle development. Twenty lactating dairy cows were fed mixed silage and concentrates twice daily. The control diet was a typical ration for high producing dairy cows in the United Kingdom (crude protein (CP)=17.5%; metabolizable energy (ME)=11.8 MJ/kg DM). The cows were ...
متن کاملAssociation between Plasma and Milk Urea on the Insemination Day and Pregnancy Rate in Early Lactation Dairy Cows
Lactatingdairy cows (n=177) fed with grass and corn silage ad libitum kept in pasture, were randomly assigned to evaluate how urea nitrogen in plasma and milk can be related to their pregnancy rate. Blood and milk samples were collected on the artificial insemination (AI) day to evaluate plasma urea nitrogen (PUN) and milk urea nitrogen (MUN) as well as progesterone levels, excluding cows with ...
متن کاملRelationship between intake and duodenal flows of linoleic acid in dairy cows fed lipid-supplemented diets.
متن کامل
Hormonal, Nutritional, and Immunological Interactions Associated with Efficient Dairy Cattle Reproduction
Efficient reproduction is important for optimal profitability on dairy operations. Unfortunately, most dairy farms do not attain optimal reproduction due to many factors related to management, health, and physiology of high-producing dairy cows. The physiology issues involved in reproduction of lactating dairy cows are complex but increasingly, the interactions between nutrition, the hormonal s...
متن کامل