Evaluation of the nutritive value of single-cell protein (Pruteen) for lactating dairy cows

Abstract

SummaryTwo experiments were conducted with four lactating cows in a latin-square design. The rations were composed mainly of maize silage plus concentrates, supplemented with urea, Pruteen, or soya-bean meal supplying 25% of total dietary N. Nitrogen and energy balances were measured, and milk production recorded.Dry-matter digestibility, intake of metabolizable energy (ME) and ME concentration in dietary dry matter were not significantly altered when Pruteen was substituted for soya-bean meal. However, mean nitrogen digestibility for all the treatments was significantly lower than expected from published relationships.The substitution of Pruteen for soya-bean meal did not significantly affect the nitrogen balance of the animals or milk production, but the latter tended to be higher than that recorded with urea.The responses to the different N supplements are discussed in relation to the feeding systems of the Agricultural Research Council and the French Protéines Digestibles dans l'lntestin Grêle, and are compared with predictions made from statistical relationships developed in our laboratory.