The degree of maternal nutrient restriction during late gestation influences the growth and endocrine profiles of offspring from beef cows

Abstract

Context: Cow–calf operations in Argentina are managed under extensive grazing condition and the quality of forages is often poor during the second half of gestation. The severity of nutrient restriction in bovine gestation, caused by seasonal pasture production, often results in poor production traits in progeny. Aims: The objective of the current study was to determine whether different levels of maternal nutrient intake in beef cows during late gestation affect fetal and postnatal growth, glucose metabolism, and insulin-like growth factor 1 (IGF1) concentrations in offspring of beef cattle. Methods: At 180 ± 4 days of gestation, multiparous Angus cows (n = 56) were blocked by bodyweight (BW) and expected calving date, and assigned to pens (2 or 3 cows/pen). Pens (n = 8 per treatment) were then randomly assigned to the following treatments: severely restricted (SR; 50% of net energy and 58% of CP requirements), moderately restricted (MR; 75% of net energy and 85% of CP requirements), or control (CON; 100% of net energy and 116% of CP requirements). Pen was the experimental unit and data were analysed by ANOVA or repeated measures analysis, as appropriate. After calving, all cows were managed in a single group until weaning. Key results: Cow BW and body condition score decreased as nutritional restriction increased (P < 0.05). At parturition, birth weight of calves from SR dams and MR dams was lower than that of calves from CON dams (P = 0.05; 4.9 kg and 2.1 kg respectively). Average daily gain of calves from birth to 24 days of age was higher (P = 0.01) in calves from SR dams than in calves from CON and MR dams. Calves from MR dams were lighter (P = 0.04) than were calves from SR and CON dams at weaning. Treatments did not affect milk production or composition (P > 0.10) or glucose–insulin metabolism of offspring during lactation (P > 0.10). Concentration of IGF1 tended to be lower in MR progeny than in SR and CON progeny during lactation (P = 0.09). Conclusions: Late gestation maternal nutrient restriction, irrespective of the severity of the restriction, decreased birth weight of offspring; however, severe nutrient restriction induced early postnatal compensatory growth. Implications: The severe nutritional restriction produced calves with weaning weights indistinguishable from the control cows due to early postnatal compensatory growth. However, the longer-term effects of nutritional restriction of the dam in the second half of pregnancy on metabolic and reproductive performance in replacement heifers or meat production/quality in steers is yet to be determined.