By-product feeds as sources of fiber for lactating cows fed low forage diets

Abstract

The effectiveness of the fiber in whole cottonseed (WCS), wheat midds (WM), and rice bran was evaluated in Holstein cows in early lactation (30 to 50 days) fed mixed rations, low in neutral detergent fiber (NDF) concentration. Treatments evaluated were: (T1) control, a diet formulated to 25% NDF with 19% NDF from chopped hay (NDFH); (T2) a diet formulated to 35% NDF containing 19% NDFH with the additional 10% NDF provided by a mixture of the three by-product feeds in the concentrate; and (T3) a diet formulated to 25% NDF with 10% NDFH and the remainder provided in the concentrate from by-product feeds. All cows were fed 6% of the total DM as alfalfa hay and pangóla grass hay to meet NDFH targets. Treatment differences in DM intake (18.3 kg/d), DM intake as a percentage of body weight (3.22%), milk production (32.7 kg/d), and milk protein concentration (2.65%) were not significant (P > 0.05). Reducing the NDFH to 10% resulted in a 15% (P < 0.01) relative reduction in milk fat concentration that was not prevented by restoring the NDF level with the mixture of WCS, WM, and rice bran. Despite the fact that cows consumed more energy for milk production (NEL) from T3, the energetic efficiency of milk production (Mcal-milk/Mcal-feed) was about 15% higher (P < 0.01) when the cows consumed 19% NDFH (T1 and T2). Fiber from by-product feeds was ineffective in maintaining milk fat concentration above 3.0% and did not result in improvement in milk production or efficiency of milk production. Thus, the NDF in the mixture of by-product feeds had no ruminally effective fiber value under the conditions of this experiment.