Dinâmica das concentrações de macrominerais em cordeiras da raça Santa Inês em crescimento

Abstract

The adequate nutritional management of growing lambs can positively impact the productive and reproductive responses of future matrix. The objective of this work was to evaluate, from allometric studies, the body composition and retention of macrominerals of growing Santa Inês lambs. Fifty Santa Inês lambs were used, distributed in a completely randomized experimental design in a 3 x 2 factorial scheme, three slaughter weights (20, 30 and 40 kg) and two nutritional management (ad libitum and restricted). Five animals were randomly selected and slaughtered to make up the initial reference group of the 20 kg animals. Two groups, one of six animals and one of five animals, were randomly selected and slaughtered to form the initial or reference group of animals slaughtered at 30 kg and 40 kg, respectively. Of the 34 remaining animals 18, the group of animals fed the ad libitum diet and slaughtered at 20, 30 and 40 kg (six animals per group) and 16 the group of animals submitted to nutritional restriction and slaughtered in the previously mentioned weight ranges. After slaughter, the body of each lamb was divided into eight components: carcass, head and limbs, skin, gastrointestinal tract, viscera, fat, uterus and mammary gland. All components were weighed, sampled and quantified as to the mineral content in order to reach the concentration of macrominerals in the different components. From the allometric model of Huxley and Teissier (1936) the macromineral masses (g) were staggered in the different body parts and the relationship between the mass of the minerals of each studied variable and body mass was established. There was no effect of feeding regimens (P>0.05) on macromineral deposition on any of the body components evaluated. They had early deposition for all macrominerals: head and limbs, TGI and uterus; In the carcass the deposits were late, except for the sodium that remained. The other compartments presented differentiated deposition for the minerals, and the mammary gland and body fat had deposition of calcium, sodium and magnesium late and stable potassium. There was an increase in macromineral gain in the empty body as it increased the body mass of the lambs.