Reproduction in continuously underfed Brahman cows

Abstract

This experiment examined the effects of sustained levels of undernutrition applied to grazing Brahman heifers on subsequent lifetime reproductive performance. Weaned heifers were raised to a target weight of 270 kg at three different stocking rates to obtain contrasting weight gains (0·097 kglday, L = low; 0·215 kg/day, M = medium; 0·259 kg/day, H = high). They were then subjected to common grazing in a low-quality Brachiaria humidicola pasture, where mean weight changes ranged between -0.100 and +0·300 kg/day depending upon season and physiological condition. Differences in age at first calving between L and the other treatments (200 days) were maintained in subsequent calvings. Calf weaning weights were higher in L and M than in H. The mean weight of calf weaned per cow per year was higher in M than in either L of H. Cow weight at conception increased with parity, and was higher in L than in the other treatments. Similar trends were observed for the dam's weight preand post calving, and at weaning. This trend was associated with higher weight loss during lactation in I..We conclude that in tropical grazing systems that allow only low growth rates, differences established early in reproductive life may become perpetuated for the lifetime of the animal. Management implications in the context of extensive tropical grazing systems are discussed.

Methane emissions of extensive grazing breeding herds in relation to the weaning and yearling stages in the Eastern Plains of Colombia

“…The observed LWs at reconception (Table 5) showed moderate variability, as estimated by the confidence limits, and did not differ between CW and EW treatments. These LWs are similar to those reported by Vera (1991;282-300 kg) for the first conception of heifers grazing Brachiaria humidicola, and are slightly below the LWs at the second to fourth conception recorded by Vera et al (1993;325-340 kg) for cows grazing that same pasture. They therefore appear to be the lower limit for viable conceptions carried to term in cattle of the same phenotype as used here, and extrapolating from Vera et al (1993) they are also dangerously close to the calculated asymptotic LW allowed for on low quality rangelands.…”

“…These LWs are similar to those reported by Vera (1991;282-300 kg) for the first conception of heifers grazing Brachiaria humidicola, and are slightly below the LWs at the second to fourth conception recorded by Vera et al (1993;325-340 kg) for cows grazing that same pasture. They therefore appear to be the lower limit for viable conceptions carried to term in cattle of the same phenotype as used here, and extrapolating from Vera et al (1993) they are also dangerously close to the calculated asymptotic LW allowed for on low quality rangelands. These values can be compared with the mature body sizes of well-fed and highly fertile cows grazing well managed B. decumbens pastures, that ranged between 388 and 452 kg (Vera et al 2002).…”

Bodyweight performance, estimated carcass traits and methane emissions of beef-cattle categories grazing Andropogon gayanus, Melinis minutiflora and Stylosanthes capitata mixed swards and Brachiaria humidicola pasture

“…However, the authors observed that the model underpredicted LWGs compared to our measured records. In summary, as suggested above, cow-calf systems in the Orinoco basin are complex and multidimensional (Ezzano 2005;Vera et al 1993Vera et al , 2002Vera and Ramírez Restrepo 2017). However, the present paper has only touched on a small number of their characteristics, whereas others related to additional environmental and social impacts have been addressed elsewhere (Hoogesteijn and Chapman 1997;Navas-Ríos 1999).…”

“…In contrast, young cattle (i.e. 1-3 years of age) are low priority categories in extensive systems and are relegated to low quality pastures, whereas in more intensive grazing systems young females are generally bred before reaching 3 years of age (Vera et al 1993;Vera et al 2002). The most prominent additional feature of this cattle productive system is that older cows are culled following weaning and/or during the dry season, when they have lost 15 to 25% of the LW recorded at conception as described by Vera et al (2002).…”

Effect of Body Condition at Calving and its Changes During Early Lactation on Postpartum Reproductive Performance of Zebu Cows in a Tropical Environment

“…Body condition score (HCS) is an easy and reliable measure to be used in the nianagement of cow feeding according to physiological status. Seasonal variation on pasture availability-xauses changes i n animal body weight and BCS, limiting reproductive potential, mainly during the dry season, when cows do not have enough food for maintenance and other physiological 23 processes, such as reproduction (Rae et al, 1993;Vera et al, 1993).…”