Feeding the Dry Cow

Abstract

The practice of dividing the cow's year into periods depending upon the stage of the gestation-lactation cycle should now be discarded. Feeding the dry cow is as much a factor during the first stages of lactation as the last stage of lactation is a factor during the dry period. For this reason, we cannot isolate one period and call it the dry period from a purely nutritional point of view. In terms of nutrition for the high producing dairy cow, modern feeding programs should feed the cow on a total year basis. The concept of "gestation-lactation" feeding is illustrated in Figure 1.

Traditional dairy feeding programs involve a table of nutrient requirements and tables of feed composition. The two parts must be in the same unit of measurement and their usefullness is dependent upon the precision of both. The practice of stating energy values in different ways (starch equivalent, oat unit, barley unit, net energy, total digestible nutrients, etc.) has necessitated the development of many standards and tables of feed composition. Despite many attempts to develop values for equating measures of energy and recommendations for the use of a single standard, arguments for and against standards remain.

In addition to the problems of expressions of energy, conventional systems fail to consider other important points such as feed intake and the end-products of rumen fermentation. Armstrong (1) pointed out the necessity for considering these end-products of digestion, and Kleiber (5) maintained that studies of milk formation are more of a chemical problem than a problem of energestics. Despite the known short-comings of conventional systems for feeding dairy cows, they served the dariy industry well for so long as feeding was done by experienced dairymen willing to provide considerable attention to individual cows within herds.

In recent years, several changes in dairying have taken place which created the need for a new philosophy in feeding dairy cows. Among these changes were the following: 1) The use of large herds where individual feeding cannot be properly practiced. 2) The breeding of cows for levels of production high enough to create constant problems with borderline nutrient deficiencies. 3. Feeding program which create stress conditions and result in rumen health problems.

This paper will review the theory and practice of a system for feeding dairy cows which was designed to overcome many of the problems encountered in traditional programs. The reader who is interested in a detailed listing of literature citations and a point-by-point consideration of the factors used in the program is referred to the book "Optimum Feeding of Dairy Animals" (7). In this review, general principles will be outlined instead of a detailed literature review.