Biological parameters for digestive and metabolic processes in interspecies hybrids of domestic sheep (Ovis aries) and argali (Ovis ammon polii)

Introduction of the allele pool of wild species, in particular, Argali ( Ovis ammon polii ) into the domestic sheep ( Ovis aries ) of the modern breeds is one of the promising approaches to enhancing genetic diversity and, consequently, biodiversity and nutrient availability. Study of the processes of digestion, assimilation of nutrient substrates in the body and metabolism is the basis for developing the feeding systems for animals of the novel genetic variation. The objective of this survey was to study and metabolism, digestibility, and nutrient requirements of hybrids of Romanov sheep and Argali. The experiments were performed on the wethers fitted with rumen fistulas (Vivarium of the L.K. Ernst Institute for Animal Husbandry, Moscow Province, pos. Dubrovitsy) in 2014-2015. The experimental animals were divided into three groups. Group I (control) included the purebred Romanov sheep (ROM, n = 3), group II included the F3 hybrids (HYB1, n = 3) from crossing Romanov ewes with F2 hybrid Romanov ewes and Argali (87.5 % of the Romanov sheep blood and 12.5 % of the Argali blood), and group III included the F3 hybrids (HYB2, n = 3) from crossing F2 hybrids Romanov ewes and Argali with the Edilbaj sheep (50 % of the Edilbaj sheep blood, 37.5 % of the Romanov sheep blood, and 12.5 % of the Argali blood). The rumen content and blood samples for the analysis were taken an hour before feeding and in three hours after feeding. The production of volatile fatty acids (VFAs) (using Markham distillation apparatus), the amount of ammonia-N (by the Conway microdiffusion method), amylolytic activity (photometrically), the protozoa and bacteria biomass (by centrifugation) have been measured in rumen. Hemoglobin concentration, red blood cell count and white blood cell count were determined. The levels of total protein, albumin, globulin, urea, creatinine, alanine aminotransferase (ALT), aspartate aminotransferase (AST) activity, glucose, cholesterol were estimated in blood serum. The ruminal fermentation in the hybrid animals, when compared to the purebred animals, was more active; it could be confirmed by the higher total microbial mass in hybrid animals (+37.0 % and +37.3 %, respectively, before feeding; +22,2 % and +33.3 %, respectively, after feeding), the VFA increased concentration (+17.5 % and +26.1 %, respectively, before feeding; +8.7 % and +12.0 %, respectively, after feeding), the increased amylolytic activity in rumen fluid (+10.3...+14.0 %), and the decreased ammonia concentrations (-8.4…-27.7 %). Intensified fermentation caused the better nutrient digestibility and utilization in hybrid animals. The HYB1 sheep, when compared to the control group, were characterized by the better digestibility of dry matter (+7.8 %), organic matter (+5.3 %), crude protein (+6.9 %), crude fat (+3.8 %, p < 0.05), crude fiber (+6.5 %, p < 0.05), and the nitrogen free extractable substances (NFE) (+4.5 %). The nitrogen utilization coefficient in the ROM group comprised 27.9 %, which is 8.9 % and 8.5 % less than that in the animals of the HYB1 group and the HYB2 group, respectively. The differences in the concentrations of both the carbohydrate and lipid metabolites and the nitrogen metabolites between the groups of purebred and hybrid sheep were ascertained. The analysis of blood metabolic profiles revealed the higher concentrations of glucose and creatinine, the higher albumin to globulin ratio, and the reduced cholesterol level in the hybrid animals compared to the purebred Romanov sheep. Therefore, the obtained data indicate that the metabolic processes are more intense in the hybrids than that in the purebred sheep. The data obtained can serve as a basis for developing the physiologically sound feeding programs for animals of the novel genetic variation to realize the maximum potential productivity.