PSXIV-31 Effects of bovine maternal nutrient restriction on offspring microRNA and messengerRNA expression and muscle fiber type

摘要

Cows nutritionally restricted during mid-gestation produce calves with differential fat and muscle deposition when compared to calves from non-restricted cows. However, little is currently known about effects these changes have on post-natal skeletal growth. We investigated whether calves from cows restricted in the second trimester had different expression of microRNA (miR), messengerRNA, and muscle fiber type when compared to calves from non-restricted dams. Cows were bred by the same sire, stratified by body weight (P = 0.80) and allocated to one of two treatments: maintenance (n = 16) or restricted (n = 18). Restricted cows received lower forage biomass (1662 kg/ha, dry matter (DM)) compared to maintenance (2309 kg/ha, DM). Restricted cows had mean BCS 1.55 lower (P = 0.001) than maintenance cows and weight difference of 188 kg (P = 0.024). After the second trimester, all cows and calves were treated similarly. Skeletal muscle biopsies were collected from calves at weaning, beginning of the feedlot, and harvest. Offspring from restricted cows expressed more (P < 0.05) miR-133a, -133b, -181d, -214, -424 and -486 in the biceps femoris (BF) at the beginning of the feedlot when compared to maintenance offspring. At harvest, offspring from restricted cows expressed more (P < 0.05) miR-133a and less (P < 0.01) miR-486 in the longissimus lumborum (LD) than offspring from maintenance cows. There was no change (P ≥ 0.27) in expression of Pax3, Pax7, Cdc25A, MamL1, Ezh2, and IGF-1R between offspring from the two treatment groups in the BF at the beginning of the feedlot or the LD at harvest. Expression was not different (P ≥ 0.14) in myosin heavy chain isoforms MHC-1, -2a, and -2x between offspring from maintenance and restricted in the BF at the beginning of the feedlot or the LD at harvest. These data provide novel insight into the molecular mechanism through which nutrient restriction in the second trimester alters fat and muscle deposition in the offspring.