Ganho de peso de novilhas mestiças leiteiras submetidas ou não à restrição alimentar antes do período seco

Abstract

This study was carried out on the Seropédica Experimental Station of Pesagro, Rio de Janeiro, Brazil, from April 7 to October 6 of 2005 (182 days of dry season) and utilized two groups of 11 dairy heifers (Holstein/Zebu) weighting 177,6±6 kg and 15,7±4 months age. In the pre-experimental period, for 49 days (April 7 to May 26), 11 heifers were mantained closed into a stall and submitted to a forced restriction in their daily dry matter intake which resulted in small lost of body weight (-2,9 kg in relation of initial weight) and others 11 heifers were mantained free on the pasture and gained 30,2 kg in relation to their initial weight. After this pre-experimental period, both groups were kept on the same grazing area and received a proteic-energetic supplement containing 30% urea, 30% NaCl and 40% of wheat middlings. Both groups were weighted at each 21 days; on the same data, only the group that suffered forced alimentary restriction was evaluated for their body condiction score (BCS). The animals that suffered an alimentary restriction had higher daily weight gain troughout the dry season. At the end of the experimental period the difference between the two groups was 15,6 kg. The values for body condiction score were different in the period of lost of body weight and in the re-growth phase; i.e. for a lost of 14,3 kg of body weigth the heifers had 0,68 units in their BCS and for a gain of 48,2 kg of body weigth, during the proteic-energetic supplementary phase, the same heifers had + 0,31 units of BCS.