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To determine the effects of feeding the circulating metabolite of vitamin D, 25-hydroxycholecalciferol (25OHD3), on prenatal skeletal muscle development, 38 gilts (BW on d −5 = 138 kg) in 4 replicates were randomly assigned to one of 2 corn-soybean meal-based diets. The control diet (CTL) was formulated to contain 2,500 IU D3/kg diet, while the experimental diet (25OHD3) contained 500 IU D3/kg diet + 50 μg 25OHD3/kg diet. Gilts were fed 2.7 kg of their assigned diet once daily beginning 42 d before breeding. Gilts were artificially inseminated 12 and 24 h after showing signs of estrus. At gestational d 90 (±2), when fetal muscle fiber number is established, gilts were harvested, fetuses (n = 291) were extracted and a portion of the longissimus muscle (LM) was collected for analysis. Fetal LM were cryosectioned and immunofluorescence stained. Fetal LM area, fiber number, fiber cross-sectional area and number of Pax7+ cells were analyzed.
Regardless of treatment, female fetuses had significantly larger LM areas than males (P = 0.01). No treatment difference was observed in fetal LM area (P = 0.25). Fetuses from 25OHD3-supplemented gilts had significantly more LM fibers (P = 0.04) that tended to be smaller in cross-sectional area compared with CTL fetuses (P = 0.11). A numerical increase in the total number of Pax7+ myogenic precursor cells was also observed in fetuses from 25OHD3-supplemented gilts (P = 0.12). The combination of additional muscle fibers and Pax7+ myogenic precursor cells could result in enhanced postnatal muscle hypertrophy in the progeny of 25OHD3-supplemented gilts.
Overall, these data suggest that feeding 25OHD3 to gilts during gestation may positively impact the red meat yield of their offspring.
EA Hines, JD Coffey, MA Vaughn, CW Starkey, TK Chung, and JD Starkey. Effect of feeding 25-hydroxycholecalciferol on prenatal porcine skeletal muscle development. 2011. Journal of Animal Science, 89(E-supplement 2):90.