J. Anim Sci., doi: 10.2527/jas.2006-466
©Copyright, 2007, The American Society of Animal Science
Effect of stocking rate and corn gluten feed supplementation on performance of young beef cows grazing winter stockpiled tall fescue-red clover pasture
R. Driskill 1,
J. R. Russell 1*,
D. R. Strohbehn 1,
D. G. Morrical 1,
S. K. Barnhart 2,
J. D. Lawrence 3
1 Department of Animal Science, Iowa State University, Ames 50011
2 Department of Agronomy, Iowa State University, Ames 50011
3 Department of Economics, Iowa State University, Ames 50011
* To whom correspondence should be addressed. E-mail: jrussell{at}iastate.edu.
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Abstract |
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A winter grazing experiment was conducted to evaluate effects of stocking rate and corn gluten feed supplementation on forage mass and composition and the BW and BCS of bred, 2-yr-old cows grazing stockpiled forage during winter. Two 12.2-ha blocks containing 'Fawn', endophyte-free, tall fescue and red clover were each divided into 4 pastures of 2.53 or 3.54 ha. Hay was harvested from the pastures in June and August of 2003 and 2004 and N was applied at 50.5 kg/ha at the initiation of stockpiling in August. On October 22, 2003, and October 20, 2004, 24, 30-mo-old Angus-Simmental and Angus cows were allotted by BW and BCS to strip-graze for 147 d at 0.84 or 1.19 cow/ha. Eight similar cows were allotted to 2 dry lots and fed tall fescue-red clover hay ad libitum. Corn gluten feed was fed to maintain a mean BCS of 5 (9-point scale) to cows in 2 pastures at each stocking rate and in the dry lots (high supplementation level), or when weather prevented grazing (low supplementation level) in the remaining 2 pastures at each stocking rate. Mean concentrations of CP in yr 1 and 2 and IVDMD in yr 2 were greater (P < 0.10) in hay than stockpiled forage over the winter. At the end of grazing, cows fed hay in dry lots had greater (P < 0.05) BCS in yr 1 and greater (P < 0.10) BW in yr 2 than grazing cows. Grazing cows in the high supplementation treatment had greater (P < 0.10) BW than cows grazing at the low supplementation level in yr 1. Cows in the dry lots were fed 2,565 and 2,158 kg DM hay/cow. Amounts of corn gluten feed supplemented to cows in yr 1 and 2 were 46 and 60 kg/cow and did not differ (P = 0.33, yr 1; P = 0.50, yr 2) between cows fed hay or grazing stockpiled forage in either year. Estimated production costs were greater for cows in the dry lots because of hay feeding..
Key Words:
beef cows , stockpiled forage, winter grazing , corn gluten feed
