title: Brown midrib corn silage and Tifton 85 bermudagrass in rations for early-lactation cows.
abstract: Forty Holstein cows were used in an 8-wk randomized trial to evaluate the effects of feeding combinations of forages with improved fiber digestibility on performance during early lactation. Treatments were arranged as a 2 x 2 factorial to include silage from normal (NCS) or brown midrib (BMR) corn silage with or without 10% Tifton 85 bermudagrass hay (T85). In a simultaneous digestion trial, degradation and passage kinetics and ruminal fermentation parameters were evaluated in a 4 x 4 Latin square design trial using late-lactation Holstein cows fitted with ruminal cannulas. Dry matter intake (DMI) and neutral detergent fiber (NDF) intake were greater with BMR than with NCS; however, milk yield and composition were similar among corn silage types. Inclusion of T85 reduced milk yield but supported higher milk fat percentage, resulting in similar yields of energy-corrected milk. Blood glucose concentrations were higher for BMR compared with NCS, and inclusion of T85 increased blood urea N concentrations. Treatments did not alter liquid or solid phase passage rates or rumen turnover. Corn silage type did not affect ruminal pH or volatile fatty acid concentrations, but inclusion of T85 increased pH and molar proportion of acetate but decreased butyrate. Molar proportions of propionate were greater for NCS and T85 compared with BMR and T85, resulting in an interaction. Results of this trial indicate that combinations of forages with improved fiber digestibility can be used to support intake and performance of cows during early lactation.
authors.affiliation: Animal and Dairy Science Department, University of Georgia, Tifton, GA 31793, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Castro
authors.forename: J K
authors.initials: JK
authors.lastname: Bernard
authors.forename: N A
authors.initials: NA
authors.lastname: Mullis
authors.forename: R B
authors.initials: RB
authors.lastname: Eggleston
mesh_terms: D000818:Animals; D002417:Cattle / Q000378:metabolism / Q000502:physiology*; D031744:Cynodon / Q000378:metabolism*; D004032:Diet / Q000662:veterinary*; D004043:Dietary Fiber / Q000378:metabolism*; D005260:Female; D007774:Lactation / Q000502:physiology*; D011897:Random Allocation; D012820:Silage; D003313:Zea mays / Q000378:metabolism*