Assessment of performance and physiological parameters of beef cows and their offspring as a function of production system intensification level

Abstract

The intensification of production systems for breeding herds has the potential to mitigate the effects of seasonality on forage availability and quality, contributing to the economic and environmental sustainability of beef cattle production. This study aimed to evaluate the productive parameters of beef cows and their offspring in response to different levels of production system intensification during gestation, considering the influence of fetal sex, and to analyze maternal physiological and gestational variables throughout pregnancy. A total of 72 pregnant Tabapuã cows (Bos taurus indicus) were used and allocated to three treatments: Control (CON) – unfertilized pasture with mineral supplementation; Intensive (INT) – nitrogen (N)-fertilized pasture with protein-energy supplementation during the dry season; and Superintensive (SUP) – fertilized pasture with total mixed ration during the dry season. A significant interaction between maternal nutrition and fetal sex was observed for Longissimus muscle area (P = 0.049), with a trend for greater area relative to body weight in cows from the intensive system carrying male fetuses (P = 0.102). CON cows showed greater rump fat thickness (P = 0.033), while pregnancy rates and hemodynamic parameters were not affected by the systems. Regarding offspring, male calves showed higher average daily gain, weaning weight, and ribeye area, whereas female calves demonstrated greater rump fat thickness. Calf vigor at birth was not significantly affected; however, a trend toward reduced vigor was observed in calves from SUP cows. The results indicate that, although production system intensification did not significantly enhance offspring performance under nutritional differences, sex-based differences in performance traits were evident. In addition, the analysis of maternal and gestational variables contributes to understanding the interactions between maternal nutrition during pregnancy and productive performance in different systems of intensification in beef cattle production.