A total of 900 broiler chickens were reared until slaughter (48 d) to evaluate the effect of two genotypes (A vs. B) and feeding regimes (ad libitum (AL), early restricted (ER), from 13 to 23 d of age, and late restricted (LR), from 27 to 37 d of age; restriction rate: 80%) on performance, meat quality, and breast myopathies. Calsequestrin (CS) and vascular endothelial growth factor (VEGF) expressions, and muscle fiber degeneration (MFD) were recorded at 22, 36, and 48 d. Chickens in the AL treatment had higher final live (3,482 g vs. 3,390 g; P < 0.01) and carcass weights and proportion of pectoralis major muscle (26.4% vs. 25.4%; P < 0.05) compared to chickens in the LR treatment, whereas chickens in the ER treatment had intermediate final live (3,454 g) and carcass weights, and proportion of pectoralis major muscle (25.6%). Chickens of genotype A were heavier than chickens of genotype B (3,548 g vs. 3,342 g; P < 0.001), and had a higher feed conversion rate (1.69 vs. 1.62). Chickens of genotype A also had a higher dressing out percentage (77.9% vs. 77.0%; P < 0.001), but a lower proportion of pectoralis major muscle (25.6% vs. 26.2%; P < 0.05), as well as a higher meat pH (5.98 vs. 5.89; P < 0.001), meat cooking losses (26.3% vs. 24.5%; P < 0.01), and shear force of the pectoralis major muscle (2.39 kg/g vs. 2.12 kg/g; P < 0.05). CS and VEGF mRNA were significantly lower in chickens in the ER and LR treatments compared to chickens in the AL treatment after feed restriction and during refeeding (P < 0.05). MFD scores increased with chicken age (1.25 to 1.88 and 2.42 from 22 to 36 and 48 d of age; P < 0.001) and differed between genotypes (1.67 vs. 2.03 in genotype A vs. B; P < 0.001). Neither feeding system nor genotype affected the occurrence of white striping or wooden breast condition.
Effect of feed restriction timing on live performance, breast myopathy occurrence, and muscle fiber degeneration in 2 broiler chicken genetic lines
Gratta F.;Birolo M.;Sacchetto R.;Radaelli G.;Xiccato G.;Ballarin C.;Bertotto D.;Piccirillo A.;Trocino A.
2019
Abstract
A total of 900 broiler chickens were reared until slaughter (48 d) to evaluate the effect of two genotypes (A vs. B) and feeding regimes (ad libitum (AL), early restricted (ER), from 13 to 23 d of age, and late restricted (LR), from 27 to 37 d of age; restriction rate: 80%) on performance, meat quality, and breast myopathies. Calsequestrin (CS) and vascular endothelial growth factor (VEGF) expressions, and muscle fiber degeneration (MFD) were recorded at 22, 36, and 48 d. Chickens in the AL treatment had higher final live (3,482 g vs. 3,390 g; P < 0.01) and carcass weights and proportion of pectoralis major muscle (26.4% vs. 25.4%; P < 0.05) compared to chickens in the LR treatment, whereas chickens in the ER treatment had intermediate final live (3,454 g) and carcass weights, and proportion of pectoralis major muscle (25.6%). Chickens of genotype A were heavier than chickens of genotype B (3,548 g vs. 3,342 g; P < 0.001), and had a higher feed conversion rate (1.69 vs. 1.62). Chickens of genotype A also had a higher dressing out percentage (77.9% vs. 77.0%; P < 0.001), but a lower proportion of pectoralis major muscle (25.6% vs. 26.2%; P < 0.05), as well as a higher meat pH (5.98 vs. 5.89; P < 0.001), meat cooking losses (26.3% vs. 24.5%; P < 0.01), and shear force of the pectoralis major muscle (2.39 kg/g vs. 2.12 kg/g; P < 0.05). CS and VEGF mRNA were significantly lower in chickens in the ER and LR treatments compared to chickens in the AL treatment after feed restriction and during refeeding (P < 0.05). MFD scores increased with chicken age (1.25 to 1.88 and 2.42 from 22 to 36 and 48 d of age; P < 0.001) and differed between genotypes (1.67 vs. 2.03 in genotype A vs. B; P < 0.001). Neither feeding system nor genotype affected the occurrence of white striping or wooden breast condition.
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