Abstract 663

D Mata and J Combellas

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

Livestock Research for Rural Development 1992 4(2): 40-48.

Two 3x3 Latin squares, each with the same three rumen fistulated dry cows, were carried out to evaluate the influence of multinutrient blocks (MB) on hay intake and some parameters of rumen fermentation. Trachypogon sp hay of 2.25% CP and 35.5% dry matter disappearance at 48h (DMD) was offered in Experiment 1 and Cynodon plectostachyus (star grass) hay of 6.6% CP and 57.6% DMD was used in Experiment 2. The treatments evaluated were a control diet based on hay and a mineral mixture and two different blocks containing mainly molasses, a mineral mixture, urea and either whole cotton seed or fish meal. Block intake was about one kg per day in Experiment 1 and approximately half of this amount in Experiment 2.

MB appreciably increased hay intake and rumen ammonia N in Experiment 1 (P<0.05) and did not influence these measurements in Experiment 2 (P>0.05). MB slightly increased DMD between 1 and 3 percentage units in both experiments and did not influence other parameters evaluated, such as rumen pH and molar proportions and concentrations of volatile fatty acids. The results are discussed in relation to grazing feeding trials carried out at this Institute where a small influence of MB on production parameters has been observed.