Crecimiento de corderos y productividad en ovejas Pelibuey mantenidas bajo condiciones tropicales de producción

Preweaning growth of lambs and ewe productivity are vital indicators of sheep production system success. An evaluation was done of the effects of birth season and year, birth type, sex and parturition number on preweaning growth and ewe productivity in Pelibuey sheep in a semi-extensive system in the humid tropics of Mexico. Data were from the production records of 323 ewes over a 7-yr period (2011-2017). Birth weight (BW), weaning weight (WW, at 60 d) and litter weight at weaning (LWW) were evaluated. Other evaluated factors included ewe prolificacy, preweaning mortality and lamb weight per ewe in a 240-d cycle (LW240d). All the factors affected ( P ≤0.05) the response variables. Lambs from multiple births had lower ( P <0.05) BW and WW, but higher ( P <0.05) LWW, LW240d, and mortality than lambs from single births. Lambs born in the dry season had higher ( P <0.05) BW and WW, and ewes had higher LWW and LW240d, than in other seasons. Compared to multiparous ewes (≥3 parturition), primiparous ewes had lighter lambs ( P <0.05) at birth and weaning, as well as lower ( P <0.05) prolificacy, LWW and LW240d. Birth year affected ( P <0.05) BW, WW, mortality and productivity characteristics. Preweaning growth performance was best in lambs born from multiparous sheep with a single parturition in the dry season. However, ewe productivity was highest in the dry season in multiparous ewes with two parturitions a year.