In utero exposure to early or conventional weaning and its effects on the muscle metabolomic profile of Nelore bulls

Abstract

In tropical beef cattle systems, the final third of gestation coincides with the dry season, a period characterized by increased nutritional demands due to maintenance, pregnancy, and lactation requirements. In this context, early weaning emerges as a viable strategy to reduce the nutritional burden on dams, redirecting nutrients toward fetal development. This study aimed to compare early weaning (EW; at 150 days of lactation or 80 days of gestation) or conventional weaning (CW; at 240 days of lactation or 170 days of gestation), evaluating the muscle metabolomic profile of Nelore bulls that were in utero during the intervention. Fifty-seven Nelore steers, with an initial body weight of 411.7 ± 5.99 kg and 18 months of age, were fed a total mixed ration (80:20 concentrate:corn silage) for 97 ± 1.60 days. At slaughter, approximately 2 g samples of the Longissimus thoracis (LT) muscle were collected from the left side of each of the 23 carcasses, between the 12th and 13th thoracic vertebrae, before chilling, snap-frozen in liquid nitrogen, and stored at −80 °C. The metabolomic profile was determined using proton nuclear magnetic resonance spectroscopy (1H-NMR). Metabolomic data were statistically analyzed using R software (v4.4.0) and the MetaboAnalyst 6.0 platform. Metabolites with VIP > 1 were considered significant. Pathway enrichment analysis was conducted using KEGG identifiers. Muscles from EW bulls showed greater concentration of lysine, glycerol, L-asparagine, creatinine, L-histidine, L-threonine, and L-aspartic acid, while muscles from CW bulls showed greater concentration of L-arginine, X1methylhistidine, isobutyric acid, L-valine and L-carnitine. Pathways enriched by the experimental treatments included those involved in biotin metabolism, glycerolipid metabolism, and methylhistidine metabolism. It is concluded that EW, as a fetal programming strategy, may stimulate pathways associated with lipogenesis, phospholipid synthesis, and one-carbon metabolism, in addition to supporting muscle development.