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Title: EFFECT OF CALVING DATE ON STOCKER AND FEEDLOT PERFORMANCE OF CALVES BORN IN THE NORTHERN GREAT PLAINS AND FINISHED IN THE SOUTHERN GREAT PLAINS

Author
item Phillips, William
item Grings, Elaine
item Short, Robert
item Heitschmidt, Rodney
item Mayeux Jr, Herman

Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 1/9/2006
Publication Date: 3/20/2006
Citation: Phillips, W.A., Grings, E.E., Short, R., Heitschmidt, R.K., Mayeux, H.S. 2006. Effect of calving date on stocker and feedlot performance of calves born in the Northern Great Plains and finished in the Southern Great Plains [abstract]. Journal of Animal Science. 84(2):106.

Interpretive Summary: ABSTRACT ONLY

Technical Abstract: Changing the calving season from late winter to late spring can have large effects on outputs from rangeland-based beef operations in the Northern Great Plains. The objective of this study was to determine the effect of calving season on subsequent stocker and feedlot performance. Calves (n =169) were born in late winter (LW; February), early spring (ES; April) or late spring (LS; June) in a rangeland-based beef operations in the Northern Great Plains. Each year (n=3), calves were weaned in October and shipped 1900 km to El Reno, OK. After a 14-d recovery period, calves grazed annual cool season grasses for 196 d (Stocker phase) before being fed a high energy diet for 133 d (Finishing phase). Data were analyzed using a mixed model with calving season as the independent variable. Calf was the experimental unit and year was considered to be random. Delaying calving resulted in lower (P< 0.01) initial stocker calf BW (LW = 281 kg; ES = 248 kg; LS = 193 kg; SE = 5), but increased (P > 0.01) the amount of BW gained during the stocker period (LW = 141 kg; ES = 145 kg; LS = 150 kg; SE = 2). During the finishing period, initial BW (LW = 429 kg; ES = 388 kg; LS = 339 kg: SE = 6) and hot carcass weight (LW = 346 kg; ES = 332 kg; LS = 317 kg; SE = 5) were greater (P >0.01) for calves born earlier in the year as compared to calves born later in the year, but ADG (LW = 1.13 kg; ES = 1.20 kg; LS = 1.25 kg: SE = .02) was lower (P < .01). Dressing percentage (61.3 ± 0.3%) and longissmus muscle (81.9 ± 1.2 cm3) were similar among the three CS groups. Delaying the calving season produced lighter stocker calves that gained weight more rapidly than heavier stocker calves during the stocker phase. However, during the finishing phase lighter younger calves had to be fed longer than heavier older calves and produced lighter carcasses at the end of the finishing phase.