Authors : J.A. Hinojosa-Cuellar, G. Torres-Hernandez, J. Oliva-Hernandez, E. Aranda-Ibanez, J.C. Segura-Correa and J.M. Gonzalez-Camacho
Abstract: The objectives of this study were to evaluate the effects of Genetic Maternal Group [GMG: Blackbelly (BB), Pelibuey x Blackbelly (PB) and a Synthetic group (SYN) developed from the mating of Dorper and Katahdin rams on PB ewes] as well as known environmental factors on Birth Weight (BW; n = 5938), pre-weaning Average Daily live weight Gain (ADG; n = 2235) and Weaning Weight (WW; n = 2235) in a commercial flock of hair sheep in Tabasco, Mexico. Final statistical models for analysis of BW, ADG and WW included the fixed effects of Genetic Maternal Group (GMG) of lamb (BB, PB and SYN), Birth Year (BY: 2001-2006 for BW and 2001-2004 for ADG and WW), Birth Season (BS: dry, rains and winds), Birth Type (BT: single, twin), Lamb Sex (LS: male, female) and dam Lambing Number (LN: 1-11). In addition, the ADG and WW models included the linear and quadratic effects of lamb age (LA) at weaning. A GMG x BY interaction was included in these models, since it was a significant effect (p<0.05) in a preliminary analysis as well as dam of lamb nested within GMG as a random effect. MGG affected (p<0.05) ADG and WW; higher averages were found in lambs from PB and SYN dams. The MGG x BY interaction affected (p<0.05) ADG and WW. LA affected (p<0.01) ADG in its linear and quadratic effects. All of the environmental factors had a significant effect (p<0.05) on the three variables analyzed. In conclusion, PB and SYN dams in this flock produced lambs with higher averages for ADG and WW than lambs from BB dams. According to the performance of the genetic maternal groups there was evidence of a possible genetic x environment interaction. Effects of the various environmental factors should be considered if genetic improvement programs are initiated in this flock.
J.A. Hinojosa-Cuellar, G. Torres-Hernandez, J. Oliva-Hernandez, E. Aranda-Ibanez, J.C. Segura-Correa and J.M. Gonzalez-Camacho, 2011. Pre-Weaning Performance of Lambs from Purebred and Crossbred Hair Ewes under Humid Tropical Conditions of Tabasco, Mexico. Journal of Animal and Veterinary Advances, 10: 3149-3154.