THE ESTIMATION OF NUTRITIVE-VALUE OF DAIRY-CATTLE FEED

A survey is given of different methods used for the estimation of the net energy lactation and the digestible crude protein content of forages (grass hay, grass silage, maize silage) as well as tuber crops (fodder beet, turnips, raw potatoes), by-products (dried sugarbeet pulp, pressed sugarbeet pulp), compound feeds and raw ingredients for dairy cattle. The following methods are discussed: - methods only based on chemical parameters: crude fibre and cell walls. - methods using rumen fluid from fistulated animals: the two step in vitro digestibility technique, the Hohenheim Futterwert test. - methods using enzyme (cellulase) preparations. - the near infrared reflection spectroscopy. The estimation of the energy value of raw ingredients is discussed more in detail. Formulas for the rapid calculation of the energy value of pulp and tubers are reported. The results obtained at the National Institute for Animal Nutrition in Melle-Gontrode with the two step in vitro digestion technique and a developed cellulase method are illustrated more in detail.