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Effects of maternal nutrient restriction followed by realimentation during early and mid-gestation on maternal jugular serum, umbilical cord serum, and amniotic fluid metabolite concentrations in beef cows
We have previously reported that maternal nutrient restriction from d 30 to 85 of gestation tended to increase fetal weight compared to fetuses from control fed cows; however, umbilical blood flow was similar between treatments. In addition, when cows were nutrient restricted for a longer duration and after realimentation we did not observe differences in fetal weight. Therefore, our objective was to examine the effect of early to mid-gestation maternal dietary restriction followed by realimentation on jugular serum, umbilical cord serum, and amniotic fluid metabolites. On d 30 of pregnancy, multiparous cows (initial BW = 620.5 ± 11.3 kg, BCS = 5.1 ± 0.1) were assigned to 1 of 3 dietary treatments: control (C; 100% NRC; n = 18) and restricted (R; 60% NRC; n = 30). On d 85, cows were slaughtered (C, n = 6; R, n = 6), remained on control (CC; n = 12) and restricted (RR; n = 12), or were realimented to control (RC; n = 11). On d 140, cows were slaughtered (CC, n = 6; RR, n = 6; RC, n = 5), remained on control (CCC, n = 6; RCC, n = 5), or were realimented to control (RRC, n = 6). On d 254, all remaining cows were slaughtered. Blood samples from maternal jugular vein, umbilical cord, and amniotic fluid were collected and metabolites concentrations were analyzed. At d 85, maternal serum cholesterol and lactate were elevated (P ≤ 0.03) in R cows vs. C cows. Maternal serum triglycerides, glucose, and blood urea nitrogen (BUN) were similar (P ≥ 0.28) between treatments. Umbilical cord serum lactate was greater (P = 0.05) and fructose and BUN tended to be greater (P ≤ 0.07) in R vs. C fetuses. Umbilical cord cholesterol, triglycerides, and glucose were similar (P ≥ 0.12) between treatments. At d 140, maternal lactate concentrations tended to be decreased in RR cows vs. CC and RC; however, all other maternal and umbilical cord metabolites at d 140 and 254 of gestation were similar (P ≥ 0.13) among treatments. Metabolites in amniotic fluid at d 85, 140, and 254 of gestation were similar (P ≥ 0.11) among treatment groups. The greater fetal weight previously observed in nutrient restricted cows might be due in part to the increased metabolites in fetal and maternal systems during early gestation.
Keywords: cows, metabolites, nutrient restriction