Beef cow weight variations during gestation and offspring performance: a meta-analysis

Abstract

The objective of this meta-analysis was to evaluate the effects of weight loss or weight gain of beef cows during the second and/or third trimester of gestation on the postnatal performance of the progeny. The variation in cow weight during the gestational period was calculated to standardize the treatments, being them: severe loss (SL = cows that lost more than 10% of weight); moderate loss (ML = cows that lost from 0 to 10% of weight) and weight gain (WG = cows that gained weight). The intensity of the cow weight variation effect was calculated as the mean difference (MD) with a 95% confidence interval and heterogeneity determined using the Q test and the I2 statistic. A meta-analysis of random effects was conducted for each indicator separately with the means of the control and experimental groups. Calves from WG cows were higher for birth weight (P = 0.0094); weight adjusted to 205 days (P = 0.0127) and average daily gain during pre-weaning (P < 0.0001) in relation to calves from ML cows. The W205 of calves from SL cows was 11.6 kg lower than the progeny from ML cows. The post-weaning performance of the progeny tended (P = 0.0868) to be higher in the progeny of WG cows than ML ones. The weight gain of beef cows during gestation improves the pre- and post-weaning performance of the progeny, with more evident effects in the early months of life of the offspring.

Beef heifer weight loss during gestation and its effects on progeny performance

“…On the other hand, the absence of fetal programming effects on progeny performance after birth may be a result of the adaptation and compensatory growth of calves to the growth environment, as well as the consequences of the "economic" phenotype generated in situations of nutritional stress during pregnancy (Mohrhauser et al, 2015). Complementing this hypothesis, Klein et al (2021b) found in a meta-analytic study that the effects of fetal programming are more noticeable in the early months of the progeny's life, with reflections, especially on the birth weight of the calves. Studying the severity of nutritional restriction in pregnant cows, Ramirez et al ( 2020) observed a greater recovery in weight gain from birth to slaughter in the progeny of severely restricted cows, when compared to calves from unrestricted or moderately restricted cows.…”

“…These changes in progeny performance can be permanent and can be observed in the adult life of the animal, although they are more noticeable in the initial months of the offspring's life (Klein et al, 2021b). In a meta-analytic study, Zago et al (2020) observed that the progeny of cows that consumed energy and protein above the maintenance requirements showed greater weight gain at finishing, were slaughtered 5.5 days earlier and presented meat with a higher marbling content, an aspect much appreciated by consumers.…”

“…In a meta-analytic study, Klein et al (2021b) observed higher performance of calves in the early months of life, when they were born to cows that gained body weight compared to those that lost less or more than 10% of body weight during pregnancy. In a similar study, Rodrigues et al (2021) did not observe any effect of the weight variation of the pregnant cow on the progeny performance variables, however, the authors observed losses in the carcass and meat characteristics of the offspring when the cow lost weight during pregnancy.…”

Efecto de la nutrición en el último tercio de la gestación de vacas de carne sobre el desarrollo de la progenie

“…The post-weaning performance of males was similar between the nutritional levels of cows during the last third of pregnancy (Table 2). A meta-analytical study (19) demonstrated that the weight gain of the cow in pregnancy improves the performance of the progeny, and complements that these effects of the best maternal nutrition in the pregnancy are most evident in our initial two months of life.…”