Effects of grazing allowance and system on the use of corn-crop residues by gestating beef cows.
1993
Russell J.R. | Brasche M.R. | Cowen A.M.
Duplicate fields of corn-crop residues were grazed by 3- to 11-yr-old Charolais X Angus and Charolais X Angus X Simmental cows (average BW = 630 kg) in midgestation at allowances of.41,.82, and 1.64 ha/cow in a continuous-stocking system for 56 d in 1988 (yr 1) and 1989 (yr 2) and for 51 d in 1990 (yr 3), or at.41 ha/cow in a strip-stocking system for 56 and 51 d in yr 2 and 3, respectively. Body weight gains by cows grazing continuously stocked fields at.41,.82, and 1.64 ha/cow were -.06, -.01, and.41 kg/d (P =.02), respectively. Body weight changes by cows grazing continuously stocked and strip-stocked fields at.41 ha/cow were.15 and.30 kg/d in yr 2 and -.33 and -.53 kg/d in yr 3 (system X year, P 0.08), respectively. Percentages of in vitro OM disappearance (IVOMD) of crop residues selected by ruminally fistulated steers (P =.22) and cow crop residue DMI (% of BW; P =.03) were 52.5, 1.64; 60.1, 2.87; and 61.7, 2.97 in fields continuously stocked at.41,.82, and 1.64 ha/cow after 21 to 35 d of grazing in yr 2 and 3, respectively. Selected crop residue IVOMD (P =.04) and crop residue DMI (percentage of BW, P =.07) were 58.0 and 2.46, respectively, in fields strip-stocked at.41 ha/cow. Mean yields of OM (P <.01) and IVOMD (P <.01) were 4,605, 2,136; 5,347, 2,495; and 5,761, 2,688 kg/ha in fields continuously stocked at.41,.82, and 1.64 ha/cow, respectively. Results imply that cows grazing corn-crop residues in continuously stocked fields are less likely to gain BW at grazing allowances < 1.64 ha/cow for 56 d. Differences in BW gains between cows grazing strip-stocked and continuously stocked crop residue fields were weather-dependent.
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