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Use of chromium propionate in sheep's diet and effects on offspring


The negative energy balance at the end of pregnancy and the beginning of lactation is caused by the high energy demand in these phases, causing mobilization of lipid reserves, metabolic stress and, in critical cases, metabolic diseases. Chromium has been studied as a supplement to enhance the use of glucose, among other functions. This mechanism occurs by increasing cellular sensitivity to insulin, increasing the uptake of circulating glucose. The recommended dose of chromium is not established. The aim of the project is to evaluate doses of chromium in the diet of sheep during the end of pregnancy and lactation and its effects on the matrices and progeny (fetal programming). The experiment will take place at the sheep farm of the Faculty of Animal Science and Food Engineering at the University of São Paulo. 100 sheep will be used, randomly divided into four treatments. The treatments correspond to different doses of chromium which are 0, 1, 1.5 and 2 mg of chromium propionate per kg DM of the total diet. In the sheep, blood parameters related to energy metabolism, such as NEFA, BHB, insulin, glucose, will be evaluated, with collections at 100 days of gestation (DG), 145 DG, 24h after delivery, 7 days postpartum (DPP), 30 DPP and 60 DPP. The quality of colostrum will be assessed by determining the concentrations of total protein, IgG, IgM and by the activity of ceruloplasmines, lactoperoxidases, lysozymes, glutathione peroxidases, superoxide dismutases, absorbency capacity of oxygenated radicals and antioxidant potential, with the collection occurring from 48 to 24h before delivery. On days 15, 30 and 60 postpartum, milk production will be estimated by the double weighing method. The collections for qualitative analysis of milk will be made on the same days, where the concentrations of total proteins, fat and lactose, pH, density, fatty acid profile will be determined. The offspring's performance will be evaluated by live weight until weaning at 60 days. In progeny, blood energy metabolism parameters will also be measured similar to sheep. After weaning, male lambs will go to confinement for 60 days and at slaughter, carcass and meat quality parameters will be evaluated. The study of eight genes related to energy metabolism in the liver, adipose and muscular tissue will be done, being collected in animals slaughtered at the end of confinement and at weaning. The design will be in complete randomized blocks. The statistical program will be SAS, and the mathematical model will take into account fixed and random effects. The type of delivery and sex of the progeny will be taken into account in the statistical analysis. The statistical probability will be 5%. (AU)

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