Revista Facultad Nacional de Agronomía Medellín (Dec 2004)
VARIACIONES EN EL PESO Y LA CONDICIÓN CORPORAL POSTPARTO Y SU RELACIÓN CON ALGUNOS PARÁMETROS DE EFICIENCIA REPRODUCTIVA EN VACAS CEBÚ VARIATION IN POSPARTUM WEIGHT AND BODY CONDITION AND ITS RELATIONSHIP WITH SOME REPRODUCTIVE EFFICIENCY PARAMETERS IN ZEBU CATTLE
Abstract
La presente investigación se realizó en una zona de vida de bh-T a una altura promedio de 82 msnm con temperatura de 28ºC. Se emplearon 40 vacas Cebú multíparas, en pastoreo, a las cuales se les monitorearon las variaciones de peso y de condición corporal 15 días antes del parto, al momento del parto y a partir de este cada 15 días hasta los 135 días postparto. Se recolectaron muestras sanguíneas a 25 de estas vacas para determinar la presencia de cuerpos cetónicos y realizar la dosificación de AGNE en suero. El número de parto, el peso y la condición corporal preparto y al momento del parto presentaron efecto significativo sobre el peso hasta los 120 días postparto y sobre la condición corporal hasta los 135 días postparto, cuando fueron analizados como valor absoluto (r² desde 0,32 hasta 0,95; P The present study was conducted in the bh-T life zone at an elevation of 82 masl and a mean temperature of 28°C. Forty multiparous Zebu cows in pasture were monitored for weight and body condition changes fifteen days before calving, at calving and every fifteen days for 135 days after calving. Blood samples of 25 of these cows were taken to determine the presence of ketonic bodies and conduct NEFA dosages in serum. Calving order, weight and body condition both prepartum and at calving had significant effects on weight up to 120 days postpartum and on body condition up to 135 days postpartum, when analyzed as absolute values (r² from 0,32 to 0,95; P < 0,003 and r² from 0,35 to 0,62; P < 0,001, respectively). When the same variables were analyzed as percentages of the prepartum value, calving order significantly affected weight between 15 and 60 days pospartum (r² from 0,15 to 0,21; P < 0,05). Ketone bodies were not detected via the semi-quantitative test proposed. A positive correlation was documented between weight values and body condition (r from 0,45 to 0,82; P < 0,003) and negative correlations were documented between NEFA and weight (r= 0,55; P < 0,008 at calving and r=-0,98; P < 0,0001 at 60 and 75 days postpartum) and between NEFA and body condition (r=-0,50; P < 0,01 at 15 days postpartum). Seven of forty selected cows exhibited estrus and were inseminated; four of these resulted pregnant. The descriminant analysis of reproductive variables permitted the determination of significant differences (P < 0,05) of the explanatory variables; calving order, weight and body condition at calving and at 135 days postpartum for estrus and between weight and body condition measured at the time nearest to breeding. Furthermore, this analysis produced some descriminant functions useful for classifying the cows, with high percentages of correct classifications (81,58% y 100%) for estrus and breeding, respectively.
