Evaluación de promotores de crecimiento en pollos de engorda, en un sistema de alimentacion restringida y a libre acceso

Abstract

TWO EXPERIMENTS WERE CARRIED OUT WITH BROILERS TO EVALUATE THE EFFECT OF TWO GROWTH PROMOTERS ON FEED INTAKE, BODY WEIGHT GAIN, FEED EFFICIENCY (KG FEED:KG GAIN), WEIGHT OF THE SMALL INTESTINE, MORTALITY AND DRESSING PERCENTAJE. GROWTH PROMOTERS WERE ADDED TO SORGHUM-SOYBEAN MEAL-CORN GLUTEN MEAL BASAL DIETS WITH 3040, 3100 AND 3180 KCAL OF ME/KG AND 21.5, 18.5 AND 17.5% OF CRUDE PROTEIN, FOR STARTER (0-21 DAYS), GROWER (22-42 DAYS) AND FINISHER (43-49 DAYS) RATIONS, RESPECTIVELY. IN EXPERIMENT 1, 420 CHICKS WERE USED IN A COMPLETELY RANDOMIZED DESIGN IN A 3 X 2 FACTORIAL ARRANGEMENT OF TREATMENTS. ONE FACTOR WAS THE USE OF A GROWTH PROMOTER (NONE CONTROL, FLAVOPHOSPHOLIPOL AND AVOPARCIN) AND THE OTHER, THE FEEDING SYSTEM (RESTRICTED -TO DECREASE ASCITES SYNDROME- OR AD LIBITUM). BROILERS WERE HOUSED IN ELECTRICALLY HEATED BATTERY BROODERS. EXPERIMENT 2 USED 750 CHICKS KEPT IN FLOOR PENS AND THE SAME GROWTH PROMOTER TREATMENTS, BUT UNDER RESTRICTED FEEDING ONLY. IN EXPERIMENT 1, THE USE OF GROWTH PROMOTERS HAD NO EFFECT ON FEED INTAKE BUT BODY WEIGHT GAIN AND FEED EFFICIENCY WERE BETTER (P<0.05) WITH AVOPARCIN THAN WITH THE CONTROL DIET. FEED INTAKE AND BODY WEIGHT GAIN WERE HIGHER (P<0.01) WITH AD LIBITUM FEEDING THAN WITH RESTRICTED FEEDING BUT FEED EFFICIENCY WAS SIMILAR IN BOTH FEEDING SYSTEMS. THE SMALL INTESTINE WEIGHED LESS (P<0.05) IN THE AVOPARCIN THAN IN THE CONTROL GROUP, BUT THE WEIGHT WAS SIMILAR IN BOTH FEEDING SYSTEMS. TOTAL MORTALITY INCREASED MORE (P<0.1) IN THE AVOPARCIN-THAN IN THE CONTROL GROUP, BUT MORTALITY DUE TO ASCITES SYNDROME WAS SIMILAR IN BOTH FACTORS. IN EXPERIMENT 2, FEED INTAKE WAS LOWER (P<0.05) IN THE AVOPARCIN ONES THAN IN THE FLAVOPHOSPHOLIPOL OR THE CONTROL GROUPS. BODY WEIGHT GAIN AND THE WEIGHT OF THE SMALL INTESTINE WERE SIMILAR AMONG TREATMENTS. FEED EFFICIENCY WAS BETTER (P<0.05) IN THE AVOPARCIN GROUP THAN IN THE FLAVOPHOSPHOLIPOL OR THE CONTROL ONES. THERE WERE NO STATISTICAL DIFFERENCES FOR TOTAL MORTALITY. ASCITES SYNDROME WAS SIMILAR AMONG TREATMENTS. NO DIFFERENCES WERE FOUND FOR DRESSING PERCENTAGES AND HISTOLOGICAL CHANGES IN ANY OF THE EXPERIMENTS. RESULTS INDICATE THAT AVOPARCIN IMPROVES BODY WEIGT GAIN AND FEED EFFICIENCY COMPARED TO THE CONTROL GROUP, BOTH UNDER AD LIBITUM AND RESTRICTED FEEDING CONDITIONS.