Всероссийский научно-исследовательский институт физиологии, биохимии и питания животных – филиал Федерального государственного бюджетного научного учреждения «Федеральный научный центр животноводства – ВИЖ имени академика Л.К. Эрнста»
ABSTRACT. The aim was to evaluate the effect of low protein diets, balanced on the availability of essential amino acids for intestinal absorption, on the growth rate, feed consumption, use of nutrients and meat productivity in Landrace × Large White crossbred growing pigs. In the equalizing period, piglets with initial live weight of 13-14 kg in the course of 7 d fed conventional feed, then three groups of pigs by 11-12 each were formed. The experiment was divided into two periods − rearing and fattening, The pigs in the control group fed diets with content of crude protein (CP), metabolizable energy, limiting amino acids on the basis of Russian norms. In diet of group II, the level of CP was reduced to 151 g/kg of feed during rearing and to 142 g/kg of feed during the feeding periods; limiting amino acids (lysine, methionine, threonine) were introduced additionally into the diet taken into an account their true availability in feed components. Piglets of group III fed diet with CP level 134 g and 130 g/kg of feed for two periods of experience, respectively, with the addition of the limiting amino acids as in group III. Weight gains during fattening period in groups I and II were similar (40.6 and 40.3 kg, 752 and 746 g, respectively), in group III, these figures were lower by 6.2% (P<0.05) as compared with the control group. Consumption of feed per unit of LWG in group III was also higher compared to groups I and II. In groups II and III consumption of CP (g/kg LWG) was decreased compared to the control group (by 5.98 and 9.15% respectively). The use of feed nitrogen in group II was higher by 6% vs conrtrol group. The excretion of nitrogen in the urine in groups II and III was reduced compared to control by 24.4 (P<0.05) and 33.8% (P<0.05), respectively. The reducing concentration of CP in group III from 172 to 133 g with the addition of synthetic amino acid in the same amount as in group II, decreased loss of total nitrogen in the feces and urine, but reduced nitrogen deposition in the body. Reducing the level of CP in the diet to 151 g/kg of feed in rearing and to 142 g/kg in fattening period with the addition of synthetic essential amino acids, taking into account the availability for absorption in the intestine, did not have a significant adverse effect on LWG, reduced consumption of CP per unit LWG and nitrogen excretion in the urine.
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