Abstract 665

Arelys Reaño, A Meléndez, J Márquez and J Combellas

Facultad de Agronomía, Universidad Central de Venezuela, Apartado 4579, Maracay, Venezuela

Livestock Research for Rural Development 1992 4(2): 67.

Two feeding trials were carried out to evaluate the influence of by-pass protein on the intake and live-weight gain (LWG) of growing cattle consuming a basal diet of fresh cut forage. A third trial was carried out with rumen fistulated dry cows to evaluate the effect of these supplements on some characteristics of rumen fermentation. The use of fish meal as a source of by-pass protein resulted in moderate increments in LWG without effects on forage consumption when substituting urea in a supplement based mainly on maize meal. The use of urea increased the rumen ammonia N concentration but did not affect the degradation of forage in nylon bags. The use of a supplement based exclusively on sources of by- pass protein, such as fish meal and dehydrated brewers grains resulted in small non-significant (P>0.05) increases in LWG compared with equal amounts of a supplement which is highly degradable in the rumen.