Resumo

OSORIO-ARCE, Mario M  e  SEGURA-CORREA, José C. Changes in Body Weight During the Lactation of B. taurus x B. Indicus Cows in a Dual-purpose in the Mexican Tropics.. Rev. Cient. (Maracaibo) [online]. 2009, vol.19, n.3, pp.284-287. ISSN 0798-2259.

The objective of this study was to evaluate the body weight (BW) changes during lactation of Holstein x Zebu and Brown Swiss x Zebu cows in a dual-purpose system in the forest humid tropics of Mexico. Cows from three commercial herds were weighed at calving and every month until drying. Data included 3.356 measurements from 234 cows, during the years of 2002 to 2005. Repeated measures data were analysed by parity number (1, 2, 3 and 4 or more calvings) using mixed model procedures, which included the fixed effects of herd, year of calving, month of measure, and the random effects of cow and residual. The depicted graphic of the BWs showed a continuous slight increase in the first two lactations and a trend to keep their BW constant in the group of cows with 3 or 4 or more lactations. BW at calving (BWC) and the average of all BW during the lactation for a cow (ABW) increased with parity. The adult BW of the cows was reached at the third lactation. The correlation coefficients between the BWs of a given lactation for the four group of parity ranged from 0.51 to 0.89 (P<0.05).

Palavras-chave : Dual-purpose cattle; body weight; crossbred cows; tropics.