Skeletal muscle growth is largely dependent on the proliferation and differentiation of muscle-specific stem cells known as satellite cells (SC). Previous work has shown that dietary inclusion of the vitamin D3 metabolite, 25-hydroxycholecalciferol (25OHD3), also called calcidiol, can promote skeletal muscle growth in post-hatch broiler chickens. Improving vitamin D status of broiler breeder hens by feeding 25OHD3 in addition to vitamin D3 has also been shown to positively impact progeny. Yet, whether combined pre- and post-hatch supplementation with 25OHD3 produces an additive or synergistic SC-mediated, skeletal muscle growth response remains unanswered. To evaluate the effect of combined maternal and post-hatch dietary 25OHD3 supplementation on the growth and SC mitotic activity of the Pectoralis major (PM) muscles in broiler chickens, a randomized complete block design experiment with the main effects of maternal diet (MDIET) and post-hatch diet (PDIET) arranged in a 2 × 2 factorial treatment structure was conducted. From 25 to 36 wk of age, broiler breeder hens were fed 1 of 2 MDIET formulated to provide 5,000 IU D3 (MCTL) or 2,240 IU of D3 + 2,760 IU of 25OHD3 per kg of feed (M25OHD3). Their male broiler chick offspring (n = 400) hatched from eggs collected from 35 to 36 wk of age were reared in raised floor pens. Broilers were fed 1 of 2 PDIET formulated to provide 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). Muscle was collected at days 4, 8, 15, 22, and 29 and stored until immunofluorescence analysis. Data were analyzed as a 2-way ANOVA with SAS GLIMMIX. Dietary 25OHD3 was effectively transferred from hen plasma to egg yolks (P = 0.002) and to broiler progeny plasma (days 4 to 22; P ≤ 0.044). Including 25OHD3 in either MDIET or PDIET altered PM hypertrophic growth prior to day 29 (P ≥ 0.001) and tended to reduce Wooden Breast severity (P ≤ 0.089). Mitotic SC populations were increased in PM of MCTL:P25OHD3 and M25OHD:PCTL-fed broilers at d 4 (P = 0.037). At d 8, the PM mitotic SC populations were increased 33% by P25OHD3 (P = 0.054). The results of this study reveal that combined maternal and post-hatch 25OHD3 supplementation does not produce additive or synergistic effects on SC-mediated broiler muscle growth. However, vitamin D status improvement through dietary 25OHD3 inclusion in either the maternal or post-hatch diet stimulated broiler breast muscle growth by increasing proliferating SC populations.
Keywords: 25-hydroxycholecalciferol; broiler breeder hen; broiler chickens; myogenic stem cells; skeletal muscle satellite cells; vitamin D status.
Skeletal muscle growth is largely dependent on the proliferation and differentiation of muscle-specific stem cells known as satellite cells (SC). Previous work has shown that dietary inclusion of the vitamin D3 metabolite, 25-hydroxycholecalciferol (25OHD3), also called calcidiol, can promote skeletal muscle growth in post-hatch broiler chickens. Improving vitamin D status of broiler breeder hens by feeding 25OHD3 in addition to vitamin D3 has also been shown to positively impact progeny. Yet, whether combined pre- and post-hatch supplementation with 25OHD3 produces an additive or synergistic SC-mediated, skeletal muscle growth response remains unanswered. The results of this study reveal that combined maternal and post-hatch 25OHD3 supplementation does not produce additive or synergistic effects on SC-mediated broiler muscle growth. However, vitamin D status improvement through dietary 25OHD3 inclusion in either the maternal or post-hatch diet stimulated broiler breast muscle growth by increasing proliferating SC populations. Overall, this work answers not only practical questions for the broiler industry regarding the possible benefits of combining maternal and post-hatch dietary 25OHD3 supplementation but also improves our understanding of vitamin D’s role in pre- and post-hatch broiler skeletal muscle growth.
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