Desenvolvimento ponderal de ovinos Santa Inês na fase de cria, manejados em pastagem e suplementados

Abstract

The objective was to characterize the weight development of male and female Santa Inês lambs, from birth to weaning, managed on pasture and receiving concentrated supplementation via creep-feeding. Data from 212 sheep of the Santa Inês breed were used. During the data collection period, the animals were kept on pasture of massai grass, and all paddocks were equipped with drinkers and troughs for mineral supplementation. The lambs received concentrated supplementation, ad libitum from the first day of life. To evaluate the total weight gain (GPT) and average daily gain (ADG) the lambs were weighed every 7 days. With the aid of a hypometer, the biometric measurements of the animals were taken every 28 days. Linear, simple and multiple regression models were tested to estimate live weight using biometric measurements as independent variables. The non-linear Gompertz Model was used to describe weight development using weight as repeated measures over time. There was an effect of the interaction between type of delivery and sex (<0.05) for birth weight (BW) variables. There was an effect of the type of delivery (<0.05) on average daily gain, total weight gain and weaning weight. The growth curves according to the Gompertz model showed high accuracy to describe the weight development of the category. Pearson's correlation coefficients between biometric measurements and weight were positive and significant (P<0.05). The simple and multiple equations showed high accuracy to predict the weight of the animals at weaning. It is concluded that twin birth lambs receiving concentrated supplementation via creepfeeding and managed on pasture develop more slowly than single birth lambs, but when weaned at 84 days they present compensatory gains in relation to traditional early weaning systems. The Gompertz model can be used to predict the development of animals and help in decision making and in the selection of precocious animals for the production system. All linear, simple and multiple equation models are efficient to predict the weight of animals at weaning through biometric measurements, however from a practical point of view the equation with two measures, body length and barrel perimeter, proved to be more efficient to be used, moreover, it is important to highlight that the more measures are used, the greater the predictive power of the model.