Polish Journal of Natural Sciences

Possibility of reduction of protein level in feed mixtures of similar content of amino acids digestible in the small intestine and its influence on fattener’s performance and nitrogen retention were determined. Thirty pigs (35 kg) were divided into 3 groups. The control animals were fed with diets with crude protein level suggested by polish pig feeding standards (Normy żywienia... 1993) – 17% in grower and 15% in finisher diet. In the experimental groups (I and II) the protein level was reduced about 10 or 20% respectively. No significant effect on feed intake, weight gains and feed utilization was found. The animals from the both experimental group utilized less crude protein (P=0.001) than in Control group. The significant (P=0.001) reduction in nitrogen excreted in urine and total N-excretion in both group with reduced protein level in feed mixtures, were observed. Nitrogen retention in g/day was higher for group I compared to other groups and N-retention : N intake were significantly higher (P<0.05) in both experimental groups. The reduction of crude protein level in the experimental diets did not affect slaughter performance but in group II the tendency to increase (P=0.064) in back fat thickness and decrease meat content in carcass, were observed. The results suggest that lowering the protein level in diets for high-meat crossbred pigs (Polish Large White × Polish Landrace) × (Hampshire × Pietrain) from 170 and 150 g kg to 136 g and 115 g kg in grower and finisher diets, respectively, but supplemented with synthetic amino acids, did not impact negatively production results of fatteners, but decreased nitrogen emission to the environment and cost of feed. Address: Małgorzata Kasprowicz-Potocka, Poznań University of Life Sciences, ul. Wołyńska 33, 60-637 Poznań, Poland, phone: + 48 (61) 848 72 26, e-mail: [email protected] WPŁYW POZIOMU BIAŁKA W MIESZANKACH DLA ŚWIŃ W OKRESIE GROWER-FINISZER NA WYNIKI PRODUKCYJNE, WYDALANIE AZOTU I JAKOŚĆ TUSZY Małgorzata Kasprowicz-Potocka, Andrzej Frankiewicz Katedra Żywienia Zwierząt i Gospodarki Paszowej Uniwersytet Przyrodniczy w Poznaniu S ł o w a k l u c z o w e: poziom białka w diecie, tuczniki, wydajność, jakość tuszy, retencja azotu.