Balanço de nitrogênio, derivados de purina e perfil de ácidos graxos em ovinos santa inês castrados e não castrados com diferentes níveis de restrição alimentar

Abstract

To evaluate the effect of quantitative and sexual class food restriction on nitrogen balance, microbial protein synthesis and efficiency. This evaluation was made by purine urinary derivates and fat acid profile on Santa Inês sheep meat. 30 male ovine was used. They had an average initial weight of 13,00 ± 1,49 kg. Every animal was submited to a completely randomized design in a factorial 3x2, there were three dietary levels (0, 30 and 60%) and two sexual classes (castrated and not castrated). There was only one diet with forage:concentration 60:40, Tiffton-85 (Cynodon sp) hay was used as a forage. Any effect of sexual class or interaction between levels of food restriction and sexual class was observed. Was found a positive nitrogen balance on all levels of food restriction, a lower relation between N retained/N consumed and N retained/N absorbed on level of 60%. Those purine derivate, total purine, absorbed purine, production and efficiency of nitrogen synthesis and microbial protein expressed in g/kgNDT, were responsive (p<0,05) on levels of food restriction. There were no alteration on levels of food restriction (p>0,05) those variables uric acid (mg / mmol kg0,75dia and / kg0,75dia), nitrogen efficiencies and microbial protein (g/ g kg CHOT / gMO), and the concentrations (mg / 100g ) of fatty acids C15: 0, C18: 3n6, C18: 2c12t10, C22: 1n9, C24: 1, in addition to the PUFAs relationships: SFA ω6: ω3 (C18: 0+ C18: 1) C16: 0, thrombogenicity index and activity of Δ9-desaturase C16: 0. The total lipids and C14 fatty acids: 0, C16: 0, C16: 1n9c, C17: 0, C17: 1, C18: 0, C18: 1n9t, C18: 1n9c, C18: 2n6c, C18: 3n3, C18: 2c9t11 were influenced (P <0.05) by dietary restriction levels, as well as relations PUFA: MUFA, MUFA: SFA and the activity of Δ9-desaturase C18: 0. In conclusion, the nutritional evaluation of Santa Inês ovine in food restriction, based on nitrogen balance and efficiency of microbial protein synthesis, show that are a better utilization of nutrients specially on level of 60%, and the sexual class has no influence on every single evaluated parameter. Animals that are in food restriction have desirable characteristics on meat quality. However, the relation ω6: ω3 appears as indicative factor for further studies to objectify raise ω3 fatty acid concentrations in meat lambs Santa Inês growing, for better nutritional value of meat products.