抄録
An experiment was conducted to evaluate the effects of two commercial phytases on performance and bone mineralization of male broilers from two commercial strains when included into a diet marginal in both calcium (Ca) and non-phytate phosphorus (npP). Male chicks from two broiler strains (Strains 1 and 2; 320 of each) were placed on fresh bedding across 64 pens (10 birds/pen with 8 replicates/treatment). All birds were fed a corn-soybean meal diet (22% CP, 3,086 kcal/kg) adequate in all nutrients except Ca and npP. Dietary treatments were arranged as a 2x4 factorial using 2 npP/Ca combinations and four dietary treatments: 1) standard (0.45% npP, 1.0% Ca), 2) marginal (0.35% npP, 0.87% Ca), 3) marginal + 500 FTU Phytase A, and 4) marginal + 500 FTU Phytase B. All diets were pelleted at 79 oC, crumbled and provided from 0 to 21 days of age. Individual body weights and feed consumption were recorded at 21 d of age and 24 birds per treatment were sacrificed for tibia breaking strength.
Chicks of Strain 2 were 1.7g heavier (P ≤ 0.05) than Strain 1 chicks at hatch, however there were no significant differences (P > 0.05) in body weight at 21 d of age. Body weight, body weight gain, feed consumption and bone strength were significantly decreased (P ≤ 0.05) in the marginal diet-fed birds in comparison with the standard diet-fed birds. However, all these parameters were completely reversed with supplementation of either Phytase A or B. Overall, live performance, bone breaking strength, and response to phytase supplementation were not affected by genetic strain or type of phytase utilized in the diet. These findings suggest that reducing dietary npP requires phytase supplementation to obtain normal growth performance and skeletal growth, regardless of commercial broiler strain.
