Effect of sheep diets with macadamia by-product and protected fat on the quality of fresh and frozen semen

Abstract

The ruminant diet is characterized by low lipid concentration, resulting from traditional diets composed by forage species. The use of agro industrial byproducts in animal feed may be interesting, once it reduces production costs and reduces environmental contamination. Among them, macadamia is known for interesting protein and carbohydrate contents; however, it is the amount of lipids that make it different. Fat supplementation can raise concentrations of blood cholesterol, a precursor metabolite of steroid hormones, which constitute biological membranes and possess specific and essential biological activities. The semen characteristics should be taken into account in the selection of the breeding herds, and the semen analysis makes it possible to evaluate the fertility of the sheep and allows obtaining important conclusions based on its results. The objective was to evaluate the seminal quality of Morada Nova sheep breed consuming diets supplemented with macadamia residue and protected fat. The experiment was carried out with 24 rams aged 18 or 30 months, distributed in four treatment groups: control (C), 50 g (MAC50) or 150 g (MAC150) of macadamia industrial byproduct; and 50 g of protected fat (Megalac®), added to the concentrate. Semen was collected at four intervals: before supplementation (day 0), 30, 60 and 75 days after the beginning of supplementation, and it was taken the measurements of volume, appearance, motility, vigour, turbulence, concentration and morphology. At days 60 and 75, semen was frozen for determination of plasma membrane integrity, acrosome integrity and mitochondrial activity after thawing. Analysis of variance was performed and the means were compared by the SNK test. In the analysis of fresh semen, a significant effect (p<0.05) of the treatments on motility was observed. For cryopreserved semen, there was no significate difference (p>0.05). The inclusion of 50 or 150 g of macadamia residue or 50 g of Megalac in the diet does not alter the quantitative and qualitative aspects of fresh and post-thawed semen.