OKREŚLENIE BIAŁKOOSZCZĘDNEGO DZIAŁANIA LASALOCIDU STOSOWANEGO W ŻYWIENIU OWIEC DAWKAMI O ZRÓŻNICOWANYM POZIOMIE BIAŁKA OGÓLNEGO

摘要

W badaniach na dorosłych, przetokowanych trykach i rosnących tuczonych jagniętach stwierdzono, że interakcja zachodząca między poziomami czynników doświadczalnych (poziom białka ogólnego: 10, 12, 14 i 16% x poziom lasalocidu: 0 i 33 mg/kg) wskazuje na możliwość obniżenia poziomu białka ogólnego w dawkach zawierających lasalocid (12% x lasalocid) przy zachowaniu efektów produkcyjnych uzyskiwanych po zastosowaniu dawek o optymalnym poziomie białka (16%, bez lasalocidu).%The ionophoric lasalocid, selected on the basis of own study results, was used in isoenergetic diets with different levels of crude protein in order to determine its protein-sparing properties. Effect of a combination of experimental factors (crude protein level in the ration: 10, 12, 14, 16% x lasalocid level in the ration: (-L) 0 and (+L) 33 mg/kg) was studied on: 1. ruminal metabolism of fistulized ram lambs (4 head); during eight 12-day experimental periods, ruminal milieu pH, ammonia and VFA concentration in the ruminal fluid, and size of protozoa population; 2. digestibility of nutrients in the diets, nitrogen utilization and fattening efficiency of growing ram lambs (32 head) - identification of an optimum combination, by determination of body weight gains and feed consumption during the 90 days of fattening, and by conducting a 7-day period of collection of lamb faeces and urine; 3. productivity of lambs (18 head) and parameters of slaughter analysis of lambs fed on rations with 12% crude protein supplemented with lasalocid and 16% crude protein without an antibiotic - verification of the selected combination. Lasalocid significantly decreased ammonia level, the ratio of the relative content of acetate to propionate in total VFA, and protozoa count in the rumen. N retention resulting from an increased digestibility of crude protein showed an upward trend in the presence of lasalocid in the diets. The addition of lasalocid improved lamb fattening results considerably. The interaction between the levels of experimental factors showed the possibility of decreasing to 12% the level of crude protein in the ration containing the antibiotic and of maintaining the production effects obtained using the ration with an optimum protein level (16%) without lasalocid. In the experiment, which aimed to check the selected combination (12% + L vs 16%-L), no significant differences were found between the productivity of lambs and the carcass characteristics of animals from the compared feeding groups.