The effect of crude protein in the diet on the quantity and composition of milk in Alpine goats

Abstract

The excess of protein and lack of energy in the diet of goats cause an excess of nitrogen compounds in the rumen with the release of ammonia and the increase of urea concentration in blood and milk, which adversely affects: production and processing properties of milk, environmental pollution and reproductive performance. The aim of the present study was to determine the effect of short-term (30 days) changes of meals in the view of different content of crude protein (CP) to: daily milk yield (DMY), the concentration of urea (U) and the ratio between fat and protein (F/P) in milk. Preliminary research was conducted on 72 Alpine goats, grouped into three groups (I, II, III), with 24 randomly selected goats. From kidding to weaning, goats were fed with the same meal (11 % CP), which was followed by period of short-term feeding with different amounts of CP in the meal (I -14 % low proportion, II - 16 % optimal proportion, III - 18 % high proportion). The increase of CP in portion for 4 %, 4 % and 6 % resulted in an increase of the DMY for: 1.29 L, 1.48 L and 1.91 L, and also the concentration of urea for 16, 26 and 30 mg/100 mL. The ratio of F/P decreased in I, II, and III group from 1.55 to 1.24; from 1.53 to 1.18 and from 1.39 to 1.12. Optimizing nutrition in terms of a more rational protein intake as the most expensive components of a meal, balance of the energy and protein, as well as defining the limit value of urea concentration in milk are a prerequisite for intensive production of goat’s milk.

Keywords

• goat's milk; Alpina breed; urea in milk; daily milk yield; fat to protein ratio