Exigências de minerais para Ovinos deslanados em crescimento pós-desmama

Abstract

In order to estimate the mineral requirements for hair sheep Santa Ines and Morada Nova, two studies were conducted. In study 1, 38 sheep male Santa Ines with initial average body weight of 13.00 ± 1.49 kg and approximately two months of age were used. In study 2, 32 sheep male Morada Nova with initial average body weight of 14.5 ± 0.89 kg and approximately four months of age were used. In both studies the animals were randomly distributed in three dietary levels (ad libitum, 30 and 60% restriction) and two sex classes (castrated and non-castrated) composing a 3x2 factorial design. At the beginning of each experiment, four animals of each sex classes were slaughtered and constituted the reference group for the estimation of initial empty body weight. The net maintenance requirements were calculated by the regression of the retained mineral as a function of the mineral intake. The body composition of each mineral was estimated as a function of empty body weight (EBW), and in Santa Ines breed the EBW ranged from 7.35 to 22.05 kg and in Morada Nova the EBW ranged from 7.73 to 23.19 kg. As results for study 1, no effect (P> 0.05) of sex classes on the parameters of the equations to estimate net maintenance requirements and retention coefficient was observed for the study with Santa Ines breed. Equations for estimating body composition and net mineral gain requirements did not differ (P>0.05) between sex classes, except for Mg and Mn. The equations obtained for net gain requirements of Mg and Mn for non-castrated animals were EBWG*(0.43*EBW^0.16) and EBWG*(0.72*EBW^0.21) respectively, while which for castrated animals were EBWG*(0.46*EBW^0.27) and EBWG*(0.79*EBW^0.32), respectively. In study 2 with Morada Nova breed animals, there was significant difference (P<0.05) for net maintenance requirement and retention coefficient. The castrated animals presented higher net maintenance requirement for P (0.15 vs. 0.10 g/kg BW/day) and Cu (0.26 vs. 0.17 mg/kg BW/day) and lower retention coefficient for Ca (0.58 vs. 0.75), Na (0.07 vs. 0.09) and K (0.04 vs. 0.05) for non-castrated animals. Sex classes did not influence the equations for body composition estimation and mineral requirement for gain. Mineral requirements for hair sheep differ from international recommendations. The data from this study establish the formulation of diets with adequate supply of minerals for hair sheep.