Positive correlation between the body weight of anestrous goats and their response to the male effect with sexually active bucksFrancisco G. Véliza, Pascal Poindronb, Benoît Malpauxb and J. Alberto Delgadilloa
a Centro de Investigación en Reproducción Caprina, Universidad Autónoma Agraria Antonio Narro, Periférico Raúl López Sánchez y Carretera a Santa Fe, CP 27054, Torreón, Coahuila, México
b Physiologie de la Reproduction et des Comportements, UMR 6175 INRA-CNRS-Université de Tours-Haras Nationaux, INRA, 37380 Nouzilly, France
(Received 17 February 2006; accepted 7 July 2006; published online 15 December 2006)
Abstract - In the present study, we analyzed the results of two years of response to the male effect in seasonally anestrous goats to investigate whether the activation of female reproductive activity by the male effect is related to the body weight of the females. Seventy-nine adult female Mexican mixed breed goats were used. The anestrous females were exposed during 15 days to sexually active males, and were classified into three categories according to their mean body weight SD (42 9 kg) (Light: 33 kg, n = 19; Medium: 34-50 kg, n = 46; Heavy: 51 kg, n = 14). More than 98% of the goats from the Medium and Heavy groups showed at least one estrus behavior within the first 15 days following the introduction of the bucks, versus only 63% of the females from the Light group ( P < 0.01). The interval between the introduction of the males and the onset of estrus behavior was longer in the females of the Light and Medium groups (4.2 0.8 and 3.3 0.3 days) than in the females of the Heavy group (2.0 0.2 days; P < 0.03). Also, body weight was negatively correlated with latency to first estrus (Spearman r = -0.57; P < 0.001). These results are in agreement with the hypothesis that the ability of anestrous goats to respond to the male effect is positively influenced by their body weight.
Key words: seasonality / live weight / estrus induction / teasing / body condition / biostimulation / subtropics
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© INRA, EDP Sciences 2006