|Endecott, R -|
Submitted to: Western Section of Animal Science Proceedings
Publication Type: Proceedings
Publication Acceptance Date: April 15, 2011
Publication Date: June 20, 2011
Citation: Kelly, W.L., Waterman, R.C., Roberts, A.J., Endecott, R.L., Petersen, M.K., Geary, T.W., Alexander, L.J., MacNeil, M.D. 2011. First Parity Evaluation of Body Condition, Weight, and Blood Beta-Hydroxybutyrate During Lactation of Range Cows Developed in the Same Ecophysiological System but Receiving Different Harvested Feed Inputs. Western Section of Animal Science Proceedings 62:253-256. Interpretive Summary: Winter feeding programs and heifer development are major financial inputs in extensive western production systems. To maintain a sustainable western beef cow/calf enterprise the use of harvested feeds are necessary. Identification of individuals that more efficiently utilize dietary feedstuffs and still reproduce equate to a more optimal production system. Reasearch indicates that heifers consuming 27% less harvested feed for 140-d during their yearling development has similar pregnancy rates to their unrestricted counterparts. In addition, reduced fed heifers had a $21 advantage per pregnant heifer when compared to ad-libitum fed heifers. The current study evaluated heifers who were developed on a lowered plane of nutrition and then were assigned to winter supplementation regimens consisting of either a traditional program or a program slightly lowering than traditional. Heifer’s dams were also under a reduced or normal winter feeding program. To assess the effect of treatments on these heifers during their first parity BW, beta-hydroxybutyrate, and BCS were evaluated. Body weights were higher for heifers developed as yearlings with an ad-libitum feed ration they also tended to have higher BCS. While this may be of some practical significance for the cow/calf producer, reproductive performance, longevity, calf performance and economical returns are a more noteworthy goal for a sustainable cow/calf operation. Continued long term research will be of value as this herd continues to further our understanding of the mechanisms at work and how to better utilize resources.
Technical Abstract: Reduction of harvested feed inputs during heifer development could optimize range livestock production and improve economic feasibility for producers. The objective of this study was to measure body condition and weight as well as blood beta-hydroxybutyrate (BHB) concentrations for primiparous beef heifers born from dams receiving 1.8 or 1.2 kg/d of winter supplementation during late gestation and then developed within an ad-libitum or 20% less feed post weaning. Heifer (BW) and BHB concentrations were measured (n = 32; 16/yr reared under two different feed inputs) every 7 days from d 21 to 126 post partum and body condition was measured every 14 days from d 21 to 119 post partum. The analysis of variance model included dam nutritional plane, heifer development feed intake, day of collection, and their interaction. Body condition tended to be greater (P = 0.08) during the 126-d trial in first parity heifers that were developed in the ad-libitum treatment group. Body condition was not influenced by dam winter nutrition (P = 0.21). Weekly body weights were greatest (P = 0.0002) in first parity heifers that were developed with ad-libitum feed (433 vs. 379 ± 8.90 kg, respectively for ad-libitum or 20% less feed treatment). Weekly body weights were not influenced by dam winter nutrition (P = 0.63). BHB concentrations did not differ (P = 0.33) between heifers developed differently, but tended (P = 0.09) to be greater in heifers born from dams that received the 1.2 kg/d winter supplementation. These results indicate that by reducing feed during heifer development results in lower first parity body weight and condition, and that dam plane of winter nutrition may influence the metabolism of their offspring.