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This Article Full Text (PDF) All Versions of this Article: jas.2008-1323v1 87/3/1147    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Larson, D. M. Articles by Funston, R. N. Search for Related Content PubMed PubMed Citation Articles by Larson, D. M. Articles by Funston, R. N.

Winter grazing system and supplementation during late gestation influence performance of beef cows and steer progeny

University of Nebraska West Central Research and Extension Center, North Platte, NE 69101

rfunston2{at}unl.edu

Abstract

A 2 x 2 factorial study evaluated effects of cow wintering system and last trimester CP supplementation on performance of beef cows and steer progeny over a 3 yr period. Pregnant composite cows (Red Angus x Simmental) grazed either winter range (WR; n = 4/yr) or corn residue (CR; n = 4/yr) during winter and within grazing treatment received 0.45 kg/d (DM) 28% CP cubes (PS; n = 4/yr) or no supplement (NS; n = 4/yr). Offspring steer calves entered the feedlot 14 d post-weaning and were harvested 222 d later. Pre-calving BW was greater (P = 0.02) for PS than NS cows grazing WR, whereas pre-calving BCS was greater (P < 0.001) for cows grazing CR compared to WR. Calf birth BW was greater (P = 0.02) for CR than WR and tended to be greater (P = 0.11) for PS than NS cows. Pre-breeding BW and BCS were greater (P 0.001) for CR than WR cows and PS than NS (P = 0.006) cows. At weaning, CR cows were heavier (P < 0.001) than WR cows but had similar BCS (P = 0.74). Cow weaning BW and BCS were not affected (P > 0.32) by PS. Calf weaning BW was lower (P = 0.01) for calves from NS cows grazing WR compared to all other treatments. Pregnancy rate was unaffected by treatment (P > 0.39). Steer ADG, 12^th rib fat, yield grade and LM area (P > 0.10) were similar among all treatments. However, final BW and HCW (P = 0.02) were greater for steers from PS-WR than NS-WR cows. Compared to steers from NS cows, steers from PS cows had greater marbling scores (P = 0.004) and a greater (P = 0.04) proportion graded USDA Choice or greater. Protein supplementation of dams increased the value of calves at weaning (P = 0.03) and of steers at harvest regardless of winter grazing treatment (P = 0.005). Calf birth and weaning BW were increased by grazing CR during the winter. Calf weaning BW was increased by PS of the dam if the dam grazed WR. Compared to steers from NS cows, steer progeny from PS cows had a greater quality grade with no (P = 0.26) affect on yield grade. These data support a late gestation dam nutrition effect on calf production via fetal programming.

Key Words: carcass quality • CP supplement • fetal programming • maternal nutrition • reproduction