High milk production decreases cow-calf productivity within a highly available feed resource environment

Abstract

The beef cattle industry tends to focus on selecting production traits with the purpose of maximizing cow-calf performance. One such trait is milking ability, which is considered the primary influence on weaning weight of the calf. Therefore, the objective of this study was to determine the effect of actual milk yield on reproductive performance, circulating blood metabolites, and calf performance in beef cows in the Southeastern US. Over a 2 yr period, data were collected from 237, 3- to 9-yr-old Angus-sired beef cows on 3 research stations in Tennessee. On approximately d 58 and 129 postpartum, 24-hr milk production was measured with a modified weigh-suckle-weigh technique using a milking machine. Subsamples of milk were collected for analysis of milk components. Milk yield data were used to retrospectively classify cows on actual milk yield as High ( ≥ 10 kg/d), Mod (8 to 9 kg/d), or Low ( < 8 kg/d). Cow body weight (BW) and body condition score (BCS) were collected weekly at each location through breeding. Calf BW was recorded at birth, mid-weight at d 58, and weaning. At d 58 and 129 of postpartum, milk yields were different (P < 0.001) among the treatment groups. Cow BW during the entire study were not different (P ≥ 0.22) with increasing milk yield. Timed-AI pregnancy rate were the lowest (P = 0.02) in the High milk producing cows with no difference (P > 0.05) between Low and Mod milk cows. In addition, overall pregnancy rate continued to be the lowest (P = 0.04) in High milk producing cows with the greatest pregnancy rate in Mod milk cows. Calf mid-weight at ∼d 58 was increased (P < 0.001) in calves from Mod and High milking cows. However, calf BW at weaning was not different (P = 0.22) among calves from different milk treatment groups. Results from this study suggest that even in management systems that modify the grazing environments with harvested feedstuffs, high milk production decreases reproductive efficiency. In addition, increasing milk production up to d 129 postpartum did not result in increased calf BW at weaning, indicating that the genetic potential for calf BW at weaning could not be improved with increased genetic potential for milk production.

Circulating beta-hydroxybutyrate concentration may be a predictive measurement for young cows that have a greater probability to conceive at a fixed-time artificial insemination

“…Similarly, Pushpakumara et al (2003) noted no differences in 24-h milk yield between dairy cows that were diagnosed as pregnant by early or late service. However, Edwards et al (2017) reported a decreased TAI pregnancy rate in high milk producing multiparous beef cows compared with low and moderate milk producing multiparous beef cows.…”

Application of the California Net Energy System to grazed forage: feed values and requirements

“…In this study, abundant native tallgrass prairie forage was available to those cows throughout the growing season but daughters of high milk EPD sires actually produced less milk than daughters of moderate EPD sires. Edwards et al, (2017) found that increased milk yield of beef cows resulted in no improvement in calf weaning BW. Their work suggested that selection for greater milk yield in their environment did not improve cow/calf enterprise income, although it may increase expenses and reduce the effective stocking rate.…”

BEEF SPECIES–RUMINANT NUTRITION CACTUS BEEF SYMPOSIUM: Sustainable and economically viable management options for cow/calf production through enhanced beef cow metabolic efficiency1

“…A large challenge for the cowherd, especially in limited resource environments, is an increase in selection for greater milk production. An increase in selection for milk production has resulted in beef cows under greater nutritional stress during early lactation, which ultimately reduces overall reproduction and cowherd efficiency (Edwards et al, 2017). These authors determined the impact of milk production on cow/ calf performance in Angus and Angus crossbred cows with milk ranging from 6.5 to 12 kg/d at peak milk production.…”

“…Even when forage or forage quality is abundant, the production cycle in cattle is energetically demanding due to the energetic costs of lactation and gestation. Energetic costs of lactation are even more exacerbated if genetic potential exceeds the environmental capacity (Edwards et al, 2017). Furthermore, the ability to adapt and cope with the nutritional challenges varies greatly among livestock, in which genetic potential and metabolic imprinting is likely an explanation (Gross and Bruckmaier, 2015).…”