PSXI-4 Effects of maternal chromium propionate supplementation for beef cows at late gestation on skeletal muscle metabolism in the offspring.

Abstract Late gestation marks the prominent period for fetal muscle development in-utero, pre-dispositioning offspring muscle development, and carcass value. Adequate glucose metabolism facilitates muscle fibers formation, although it can be compromised by maternal energy imbalances. Nutritional strategies such as supplementation of organic chromium propionate, in late gestation, aim to enhance insulin sensitivity and glucose metabolism, potentially improving maternal energy balance to promote efficient glucose uptake for fetal muscle development. However, this relationship between chromium and glucose in this stage of gestation is yet to be fully understood. This study aimed to evaluate the effects of maternal chromium propionate supplementation and the impacts on the growth and muscle metabolism in the offspring. One hundred late-gestation Angus-cross beef cows were randomly assigned to two treatments until parturition: control (CON, n = 50), receiving a basal diet, and chromium propionate (CRP, n = 50), receiving the same diet supplemented with 10 g/head/day of KemTRACE® Chromium 0.04% (Kemin Industries, Inc., Des Moines, IA). Cow performance was monitored from 56 days prepartum to parturition, and calf metabolic parameters were assessed at birth. From 2-10 days of age, skeletal muscle samples were collected from calves to assess gene expression and protein abundance related to adipogenesis and glucose metabolism. Maternal CRP-supplementation had no impact (P > 0.05) on calf birth weight, weaning weight, or average daily gain from birth to weaning. A treatment by calf sex interaction was observed for the number of muscle fibers, where CRP-supplemented male calves exhibited a greater number (P = 0.01) of muscle fibers compared to CON male calves. However, no significant differences were observed for muscle fiber size (P = 0.53) or muscle fiber type (P > 0.05) between dietary treatments or calf sex. Calves from CRP-supplemented dams showed increased skeletal muscle mRNA expression of adipogenic markers PPARγ (P < 0.01), ZFP423 (P < 0.01), and DLK1 (P = 0.02). Similarly, they exhibited enhanced mRNA expression of IRS1 (P = 0.01) and GLUT4 (P = 0.04) and tended to increase the IRS1 activity (P = 0.08). In summary, these findings suggest maternal supplementation with chromium propionate at late gestation affects the skeletal muscle development of the offspring likely enhancing the early intramuscular adipogenesis and glucose uptake capacity, increasing their potential for intramuscular fat deposition.