A. L. Slater,
M. L. Eastridge 1,
J. L. Firkins
The Ohio State University Department of Animal Sciences
Neutral detergent fiber (NDF) from soyhulls and whole linted cottonseed were used to replace a portion of NDF from forage (40:60 alfalfa silage:corn silage) and a portion of concentrate. Two different sources of starch, differing in rumen degradability, were evaluated when forage NDF (FNDF) was reduced to 16 %. Forty-eight cows were fed one of four diets: (1) 21% FNDF with corn, (2) 16% FNDF with corn, (3) 16% FNDF with corn and wheat (1:1), and (4) 11% FNDF with whole linted cottonseed (WCS) and corn. Experimental diets were fed during weeks 10 to 25 of lactation as a TMR. Actual FNDF concentrations were two to three units lower than formulated. Dry matter intake and milk yield were highest for cows fed 11% FNDF with WCS. Milk fat percentage and yield were highest for cows consuming 16% FNDF with corn and lowest for cows consuming 16% FNDF with corn and wheat. Cows fed 11% FNDF with WCS and 16% FNDF with corn and wheat had the highest milk protein yield but lowest protein percentage. Cows fed 16% FNDF with corn and wheat showed fat-protein inversion. For cows in midlactation, FNDF may be reduced to 9 to 11% when WCS is at 11% of the DM and dietary starch is reduced to 30% of the DM. Forage NDF may be reduced to 14 to 16% without WCS when concentration of rumen degradable starch is monitored and starch is at 30% of the DM. It is still uncertain whether FNDF concentrations at these levels are appropriate for early lactation cows.
1For more information, contact at: The Ohio State University, 221B Animal Science Building, 2029 Fyffe Road, Columbus, OH 43210-1095; 614-688-3059; fax: 614-292-1515; e-mail: eastridge.1@osu.edu