Effect of the Concentrations and Quality of Protein in Diets for Growing-Finishing Pigs on Nitrogen Excretion to the Environment

The objective of this study was to determine the effect of the concentrations and quality of protein in diets for growing-finishing pigs on total protein digestibility, and on the levels of nitrogen retention, utilization and excretion to the environment. Digestibility and balance trials were conducted on 24 young hybrid (Polish Large White x Polish Landrace) x Duroc) boars, placed in individual metabolism cages equipped for quantitative collection of feces and urine. The boars were divided into three experimental groups, of 8 animals each, and were fed grower and finisher diets differing in the concentrations of total protein, lysine, methionine, threonine and tryptophan. Control diet l contained standard amounts of total protein and essential amino acids, diet 2 contained reduced amounts of total protein (by 15 % to the standard level) and essential amino acids, and diet 3 contained reduced amounts of total protein and standard (as in control diet 1) amounts of essential amino acids. U was found that a decrease in the levels of total protein and essential amino acids (lysine, methionine, threonine and tryptophan) in grower diets negatively affected protein digestibility and nitrogen balance parameters. The analyzed experimental factor had a beneficial influence on urinary and fecal nitrogen excretion in pigs fed on finisher diets. The supplementation of diets with a decreased total protein content with essential amino acids had no statistically significant effect on nitrogen balance. It was estimated that a 15 % reduction to the standard level in total protein concentrations and a decrease in essential amino acid levels in grower and finisher diets reduced nitrogen excretion to the environment by 5.38 to 16.81 %.

Celem pracy było określenie wpływu poziomu i jakości białka w mieszankach paszowych dla tuczników na strawność białka ogólnego, retencję azotu i jego wykorzystanie oraz na ilość wydalanego azotu do środowiska. Materiał doświadczalny w badaniach strawnościowo-bilansowych stanowiły 24 wieprzki, mieszańce ras (wbp x pbz) x Duroc. Tuczniki umieszczono w indywidualnych klatkach metabolicznych, przystosowanych do ilościowego zbierania kału i moczu. Zostały one podzielone na 3 grupy doświadczalne po 8 osobników w każdej i żywione mieszankami Grower/Finiszer o różnej koncentracji białka ogólnego, lizyny, metioniny, treoniny i tryptofanu. Mieszanka l-K zawierała standardową ilość białka ogólnego i aminokwasów egzogennych; mieszanka 2 miała obniżony o 15 % w stosunku do standardu poziom białka ogólnego i aminokwasów egzogennych; w mieszance 3 zmniejszona ilość białka ogólnego została wzbogacona w aminokwasy egzogenne do poziomu jak w mieszance 1-K.