Abstract This 3-yr study evaluated the effects of access to artificial shade during late gestation on the plasma metabolome of beef cows before calving and their offspring at birth. On day 0 of each year (92 ± 20 d prepartum), 176 multiparous, pregnant Brangus cows were stratified by body condition score and body weight and allocated into 16 bahiagrass (Paspalum notatum) pastures (8 ha and 11 cows per pasture). Gestational treatments were randomly assigned to pastures and consisted of cows provided (SH) or not (NSH) access to artificial shade (4.5 m2 per cow) from day 0 to 90. Cows and calves were managed similarly from calving to day 330 (weaning). Blood samples were collected from 3 cows per pasture on days 0, 30, and 60 and from 3 calves per pasture at birth to determine the plasma metabolome using liquid chromatography. Principal component and partial least squares-discriminant analyses were performed within each day to discriminate the treatments. Single metabolite concentrations were compared between SH and NSH groups using the MIXED procedure in SAS, and differentially expressed metabolites were analyzed for canonical pathways using the Ingenuity Pathway Analysis. A clear separation was observed on days 30 (R² = 0.76) and 60 (R² = 0.67) for the plasma metabolome of SH and NSH cows. Effects of treatment (P ≤ 0.05) were detected for 23 metabolites on day 30 and 17 metabolites on day 60 from the top 100 variable importance in projection. Twelve pathways related to putrescine, glycine, and arginine metabolism were downregulated (P ≤ 0.04), whereas tryptophan degradation X was upregulated (P = 0.02) in SH vs. NSH cows on day 30. On day 60, 25 pathways, mostly related to cysteine, serine, and methionine biosynthesis, were upregulated (P ≤ 0.05), whereas 4 pathways related to amino acid degradation were downregulated (P ≤ 0.01) in SH vs. NSH cows. A clear separation was observed for the calf plasma metabolome at birth (R² = 0.73). At birth, effects of treatment (P ≤ 0.03) were detected for 10 metabolites, and 50 metabolic pathways were upregulated in calves born from SH vs. NSH cows. Most metabolic pathways impacted were related to amino acid metabolism, specifically glutamate, histidine, and alanine, as well as the antioxidant response. Thus, access to shade for pregnant beef cows altered their amino acid metabolism compared with no access to shade. Prenatal access to shade programmed the calf metabolism at birth, improving amino acid metabolism and antioxidant responses.
Izquierdo et al. (Wed,) studied this question.