I. Varlyakov*, V. Radev, Т. Slavov, R. Mihaylov
Departmet of Morphology, Physiology and Animal Nutrition, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria
Abstract. A physiology experiment was conducted to evaluate the effects of diet supplementation with non-protein nitrogen compounds Optigen and urea. The trialcomprisedthreeperiods:control–yearlingsheepwerefed rationwithbarley,sunflowermealandmeadowhay;firstexperimental–thesamerationwas supplemented with 12 g Optigen and second experimental – the ration was supplemented with 10.6 g urea. The addition of Optigen resulted in increased appetite and faster consumption of the food as seen from lower feeding time and increased rumination time. The welfare of animals was good as seen from the low ratio of time spent ruminating in standing position to total rumination time and the dominating values of rumination and rest times without statistically significantdifferencesbetweenexperimentalperiods.Therewerenodifferencesbetweentimesspentstandingand loafing,includingmovementinsidethe box, which is an indirect index for lack of discomfort and reliable testimony for the conditions of the present experiments. The blood picture results allowed affirming that the health status of experimental animals was within the reference limits. Proofs in support of this thesis were the fact that lower red blood cell counts were compensated by the higher haemoglobin content, whereas white blood cell counts were normal and accompanied by nutritional leukocytosis during all three study periods.