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ARS Home » Southeast Area » Tifton, Georgia » Crop Genetics and Breeding Research » Research » Publications at this Location » Publication #84969
Title: INTAKE MILK YIELD AND DIGESTION BY DAIRY COWS OFFERED DIETS WITH INCREASINGFIBER CONTENT FROM BERMUDAGRASS HAY OR SILAGE

Author
item WEST, J - UNIVERSITY OF GEORGIA
item MANDEBVU, P - UNIVERSITY OF GEORGIA
item HILL, G - UNIVERSITY OF GEORGIA
item Gates, Roger

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/18/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Lactating dairy cows were offered rations containing increasing quantities of bermudagrass hay or silage and increasing dietary neutral detergent fiber (NDF) content to determine the effects of bermudagrass storage method and dietary fiber content on intake, milk yield, and nutrient digestion. Bermudagrass was added as hay or silage at the rate of 8.5, 15.9, or 23.3% of diet dry matter and was substituted for an equal quantity of corn silage. The bermudagrass storage method did not affect intake (kg/d), but increasing bermudagrass and NDF in the diet reduced intake. Dietary NDF was well above minimum recommendations. Milk yield was not altered by bermudagrass storage method but declined with increasing dietary NDF. Digestion of NDF was lower for diets containing bermudagrass silage than for bermudagrass hay diets. Increasing bermudagrass in the diet improved digestion of dietary dry matter, acid detergent fiber, and NDF, because greater quantities of digestible fiber were added with bermudagrass. Improved NDF digestion with added bermudagrass hay or silage was confirmed by in vitro analysis. High quality bermudagrass hybrids have potential for use in rations for lactating dairy cows because of good digestion characteristics and relatively small effects on intake despite high dietary fiber content. Tifton 85 bermudagrass may serve as a forage alternative for lactating dairy cows.

Technical Abstract: Highly nutritious forages are a necessary feed ingredient for dairy cattle in order to maintain animal health and productivity. Alfalfa, is often imported at considerable cost to provide high quality forage for dairies in the Southeast. Previous research demonstrated that Tifton 85 bermudagrass, which can be produced locally with high yields, can replace alfalfa at moderate levels without depressing milk yield. This investigation examined the response of lactating cows to rations containing from 9 to 23% Tifton 85 bermudagrass as hay or silage. Daily feed consumption and resulting milk yield declined as the level of bermudagrass in the ration increased. However, cows were able to consume quantities of plant fiber (NDF) much higher than current mathematical models predict. Evidently, the fast rate of digestion and overall digestibility of Tifton 85 contribute to its high nutritional quality. Our research confirms the uniqueness of Tifton 85 and it substantial potential to reduce feed costs for southeastern dairy farmers. The need for clearer understanding of plant fiber digestion and utilization is also highlighted.