Effect of maternal and post-hatch dietary 25-hydroxycholecalciferol supplementation on broiler chicken growth characteristics and skeletal muscle satellite cell activity
Type of DegreeMaster's Thesis
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Including the vitamin D3 (D3) metabolite, 25-hydroxycholecalciferol (25OHD3) in broiler diets, has been shown to enhance the proliferative activity of skeletal muscle satellite cells (SC), induce the expression of pro-myogenic factors and ultimately improve the broiler meat yield. Previous research demonstrates that 25OHD3 has an important role during embryonic development and in other species, maternal dietary 25OHD3 has exerted positive myogenic responses in the offspring. We aimed to understand how the inclusion of 25OHD3 in maternal and post-hatch diets alters the broiler growth characteristics and the skeletal muscle SC activity. Two randomized complete block design experiments with the main effects of maternal diet (MDIET) and post-hatch diet (PDIET) arranged in a 2 × 2 factorial treatment structure were conducted. All diets were formulated to provide 5,000 IU of vitamin D per kg of feed. Parent stock broiler breeder hens reared without 25OHD3 were provided 1 of 2 MDIET during the laying period: 5,000 IU D3 (MCTL) or 2,240 IU of D3 + 2,760 IU of 25OHD3 per kg of feed (M25OHD3). Their broiler chick offspring hatched from eggs collected at breeder age wk 37 and 38 (Experiment 1) and from 35 to 36 wk (Experiment 2) and were fed 1 of 2 PDIET: 5,000 IU of D3 per kg of feed (PCTL) or 2,240 IU of D3 + 2,760 IU of 25OHD3 per kg of feed (P25OHD3). In the 1st experiment, no MDIET × PDIET interactions were observed (P ˃ 0.05). Broilers from 25OHD3-fed hens (M25OHD3) were heavier at d 40, and their tender weight and yield were increased compared with broilers from MCTL-fed hens (MCTL; P = 0.001). Breast, bone-in wings, and boneless thighs tended to be heavier in broilers fed 25OHD3 (P25OHD3) compared with those fed D3 (PCTL; P ≤ 0.078). In the 2nd experiment, we demonstrated that 25OHD3 was effectively transferred from maternal diets to the breeder egg yolk (P = 0.002), and its inclusion in post-hatch diets increased the broiler circulating vitamin D concentrations (d 4 to 29; P ≤ 0.086). Including 25OHD3 in either MDIET × PDIET diet combinations altered the Pectoralis major hypertrophic growth prior to d 22 (P ≥ 0.001) and Wooden Breast (WB) severity at d 29 (P ≤ 0.089). No synergism was observed when combining maternal and broiler dietary 25OHD3 (M25OHD3:P25OHD3; P > 0.05). Early post-hatch SC proliferation was increased in the Pectoralis major when 25OHD3 was included in either maternal or broiler diets (P = 0.037). Likewise, maternal 25OHD3 supplementation (M25OHD3) induced a similar response in the Biceps femoris muscle (P = 0.001). Even if no synergistic effects were observed by feeding 25OHD3 during pre-hatch and post-hatch periods, our findings demonstrate that including this metabolite in either maternal or broiler diets improved the broiler meat yield at d 40. Including the 25OHD3 metabolite in either maternal or broiler diets induced an early skeletal muscle SC proliferation in the Pectoralis major. Altogether, maternal or broiler dietary 25OHD3 supplementation as separate strategies can improve the broiler meat yield, through SC-mediated hypertrophic growth mechanisms.