Efectos de la restricción nutricional durante la gestación sobre la producción de leche de ovejas Pampinta y la respuesta productiva de los corderos

Effects of nutritional restriction during gestation on milk production of Pampinta ewes and the productive response of lambs

Abstract

Sheep are distributed throughout most of Argentina due to their hardiness and adaptability. Production systems based on natural pasture systems frequently present periods of undernutrition during the gestation stage, since small ruminants are destined to pastures of low availability and poor quality. The present work has as objective to know about the effects of nutrition, with special emphasis on undernutrition, of the pregnant sheep reproductive development of its female offspring and on the dairy productive behavior of the mother sheep and its offspring. As well as the quality of the meat in the male lambs, and the weight evolution of the offspring. One hundred and eight pregnant Pampinta ewes were randomly distributed in two groups, 1) controls (C) feed according to their nutritional requirement; 2) ewes with nutritional restriction (NR) of 50% pre-lambing (day 59 to 100 of gestation). The NR ewes showed a reduction in body condition (CC) of one point during the trial period, with less weight gain than the T ewes. Regarding the weight of the lambs, there were no significant differences between treatments, with an average birth weight (BW) of lambs from mothers with NR of 5.46 (0.09) and those from mothers T of 5.35 (0.08). PN was not significant with maternal age (P 0.51). There were no significant differences in milk production (LP), fat percentage (%G), protein percentage (%P) and solids not fat (SNF) for both treatments.  NR ewes produced milk in almost the same days in milk (DIM) tan the T. The fat component, which is always affected by a change in diet, was always lower in the restricted (7.693±0.6) mothers than T (7.923±0.58). Although not significantly. Regarding carcass and meat quality of the male offspring of both groups, no statistically significant differences were found for the degree of fatness. The rib eye area (AOB) was affected by the treatment variable. Being significantly greater in animals with NR. For dorsal fat thickness (EGD), capacity of wáter retention (CRA), GR point, hot and cold carcass yield, hot and cold pH, there were no significant differences. For morphometric measurements: carcass length (LC), leg length (LP), rump width (AG) and thorax width (AT) there were no differences between treatments. There were significant differences for cooking losses (PCC) for those animals that had RN. Regarding the reproductive efficiency of the daughters of these ewes, the pregnancy rate for T ewe daughters was 68.96% and for NR was 44.44%. The low level of feeding of the ewes during gestation did not cause detrimental effects on the carcass characteristics of the lambs at the time of slaughter. There were also no effects on their PV or growth. There were no effects on the mothers' lactation performance, but there were effects on their offspring.