Dietary energy in late pregnancy and during lactation and performance of Santa Inês sheep in an accelerated mating system

Abstract

The objective of this study was to evaluate feed energy concentration in the last third of pregnancy and during lactation of ewe in an accelerated mating system. Three rations with different energy content were evaluated: 2.0; 2.2 and 2.4 Mcal of ME/kg DM, which were randomly distributed to the animals. Experimental rations were fed to animals in the last third of pregnancy and lactation for three consecutive productive cycles. Before start each period of provision of the rations, only females gestating one lamb were selected from a flock of 50 animals, being utilized 18; 19 and 18 ewes in the first, second and third cycle, respectively. At the beginning of each experimental period, ewes were at 105 days of gestation with an average body weight of 52.00 kg and average body condition score of 3.00. Newborn lambs remained with their mothers until weaning, at 60 days of age. After weaning, all ewes were managed on pasture, being supplemented daily with sorghum silage and concentrate based on corn and soybean meal. It was aimed the reduction of lambing interval through the reproductive management. From the beginning of the provision of the rations until weaning there was a linear increase in body weight and body condition of the ewes, as energy concentration increased. It was also verified a positive linear effect of energy content on weight of lambs from birth to weaning, and on average daily weight gain (0.125; 0.176 and 0.220 kg, for 2.0; 2.2 and 2.4, respectively). Females fed with 2.0 Mcal of ME/kg of DM presented the worst indices for lambing rate (66.7; 100.0 and 83.3%), birth rate (72.2; 105.3 and 88.9%) and service period (131.1; 128.4 and 122.2 days, for 2.0, 2.2 and 2.4, respectively). The season of provision of rations did not affect any of the productive or reproductive parameters evaluated. Santa Inês ewes can be used for lamb production in an accelerated mating system, since the nutritional management of the herd is controlled in order to maintain intermediate body scores (2.5 to 3.5). Diet containing 2.0 Mcal ME/kg DM do not meet energy requeriments for Santa Inês ewes in late pregnancy and during lactation.