ARS | Publication request: Annual grass as supplements for beef cows

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: August 5, 2009
Publication Date: August 13, 2009
Citation: Gunter, S.A. 2009. Annual grass as supplements for beef cows. Proceedings K-State Beef Conference, August 13, 2009, Manhattan, KS. 12 p.

Technical Abstract: Research has shown when limit grazing cool-season annual grasses as a supplement in a complementary forage system, energy and CP supplementation are not required and hay requirements are reduced 23% for gestating beef cows. To further improve the sustainability of complementary forage systems, replacing annual grasses with perennial grasses should prove beneficial on the Coastal Plains. On 17 December 2003 near Hope, AR, 144 beef cows (BW = 1195 +/- 25.4 lb) were divided into 6 groups of 24. They were stratified by body condition score (BCS), body weight (BW), and age and then assigned to graze a forage system for 3 yr. Each forage system (n = 3/treatment) contained 12.5 acre of bermudagrass plus either 6 acres of Jessup tall fescue infected with AR542 endophyte (7 hr/d; 0.01 acre/cow/grazing-d) or 6 acres of Wintergrazer 70 rye/Passeral Plus ryegrass (winter) and Redriver crabgrass (summer; 7 hr/d; 0.01 acres/cow/grazing-d) up to 3 d/wk when forage was available. All pastures had ad libitum access to bermudagrass/dallisgrass hay (9% CP, 54% TDN) from October through April. Rye/ryegrass was established by light disking and broadcasting the seed (90 and 20 lb/acre of rye and ryegrass, respectively) into the crabgrass sod. In late April, a bull was placed with each group for 60 d and pregnancy determined in September. Grazing system had no affect (P > 0.36) on cow BW or BCS at any point during the trial. Pregnancy rate with annual grasses (90%) did not differ (P > 0.74) from cows grazing tall fescue (91%). No differences (P > 0.44) were noted between calves grazing annual or perennial grasses in weaning weight (459 vs 456 lb, respectively), ADG from birth until May (2.09 vs 2.09 kg, respectively), or ADG from May until weaning (1.90 vs 1.90 lb, respectively) as a result of treatment. Birth weight tended to be greater (P = 0.06) for calves on annuals (76 lb) vs perennials (75 lb). Cows grazing complementary forage systems with either annual or the perennial grasses performed similarly. Advantages for either system would result from difference in cost of production.