Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/14/2005
Publication Date: 6/1/2006
Citation: Soder, K.J., Sanderson, M.A., Stack, J.L., Muller, L.D. 2006. Intake and performance of lactating cows grazing diverse forage mixtures. Journal of Dairy Science. 89:2158-2167. Interpretive Summary: Maximizing feed intake of lactating dairy cows is crucial to maintaining high levels of milk production, especially when grazing. Intake can be strongly affected by the amount and type of forage offered to the animals. Pastures containing multiple plant species have been shown to have greater plant productivity than pasture planted with a single plant species. However, it has not been determined whether this increase in plant productivity translates into increased animal productivity. Therefore, a study was designed to evaluate the effects of varying levels of plant species diversity on intake, grazing behavior, and productivity of lactating dairy cows. Twenty lactating dairy cows were grazed on one of four pasture treatments. Pasture treatments were: a two-species forage mix, a three-species mix, a six-species mix, or a nine-species mix. The results of this study suggest that managing for a moderately complex (3 to 5 forage species) mixture of forages on pasture may result in greater carrying capacity of the pastures due to increased forage productivity (and quality) and reduced weed competition, while maintaining high levels of milk production. Despite shifts in species composition, proper grazing management and strategic supplementation can buffer changes in milk production.
Technical Abstract: Twenty multiparous Holstein cows in mid-lactation grazed pastures of four forage mixtures in a 13-week study repeated during two grazing seasons to determine if forage mixtures affected intake and productivity of lactating dairy cows. The forage mixtures were: 1) orchardgrass plus white clover (2SP), 2) orchardgrass, white clover, and chicory (3SP), 3) orchardgrass, tall fescue, perennial ryegrass, red clover, birdsfoot trefoil, and chicory (6SP), and 4) 6SP mix plus white clover, alfalfa, and Kentucky bluegrass (9SP). Total dry matter intake was not affected by treatment but was affected by year and averaged 22.9 kg/d in 2002 and 19.8 kg/d in 2003. Milk production and composition were not affected by treatment or year and averaged 34.6 kg/d, 3.4%, and 2.8% for milk production, milk fat percentage, and milk protein percentage, respectively. Blood glucose, blood urea nitrogen, and non-esterified fatty acids were not affected by pasture treatment. The complex mixtures (3SP, 6SP, and 9SP) produced more herbage than the simple orchardgrass-white clover (2SP) mixture during 2002 (drought), and also had reduced weed pressure. These results suggest that managing for a moderately complex (3 to 5 forage species) mixture of forages on pasture may result in greater carrying capacity of the pastures due to increased forage productivity and reduced weed competition, while maintaining animal productivity. Despite large shifts in species composition, proper grazing and supplementation management can buffer changes in milk production.