Submitted to: Journal of Dairy Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/15/2000
Publication Date: N/A
Citation: Interpretive Summary: The starch in corn kernels contained in corn silage is not completely digested by lactating dairy cows, resulting in waste and loss of nutrients. The situation worsens if corn silage is harvested after the window of optimum harvest has passed. Timely harvest of corn silage is often delayed due to weather or simply because the amount of corn silage to be harvested stretches the labor and machinery resources available. Thi series of three experiments examined the potential of roller milling (kernel processing) for improving the nutritive value of corn silage. Corn silage that was processed at the time of harvest was compared to control corn silage that was not processed. Three lactation trials were conducted, and milk production, milk composition, and feed intake were measured. The digestibility of starch was also measured. There were indications that starch digestion was increased in two of the trials, and that dry matter intake was increased in one trial. The processing of corn silage increased milk fat test in one trial, but had minimal effect on milk production in the three trials. While there was no strong evidence of benefit from processing corn silage with the maturity and moisture content used in these trials, there were trends for benefit in terms of starch digestion, feed intake, and milk fat test. While the benefits from processing were small in this study, the cost of processing can be very modest, and can often be justified by relatively small improvements in nutritive value. Results of this study will help dairy producers decide if processing of corn silage is likely to be of benefit.
Technical Abstract: We conducted three experiments to determine the influence of mechanical processing on corn silage utilization by lactating dairy cows. Total mixed rations contained either unprocessed or processed corn silage harvested between 1/4 and 3/4 milk line. In trial 1, twelve multiparous Holstein cows were used in a replicated double switchback design with 21-day periods. Intake of dry matter (DM) was increased 1.2 kg/d by processing, but milk yield was unaffected. Processing did not affect apparent total- tract DM digestibility, but processing tended to lower starch and corn excretion in feces and reduced concentration of sieved corn kernel particles in feces. In trial 2, 42 Holstein cows were used in an 18-wk randomized complete-block design. Intake of DM and milk yield was unaffected by processing, but milk fat percent was increased 0.35 percentage units by processing. Processing tended to increase total-tract digestibility of starch, but reduced organic matter, crude protein, and neutral detergent fiber digestibilities. In trial 3, 30 Holstein cows were used in a 15-wk randomized complete block design. There was no influence of mechanical processing on intake or lactation performance in this trial. Despite indications of increased starch digestion in two trials and increased DM intake in one trial, effects of processing corn silage on lactation performance were minimal with corn silage at the maturity and moisture contents used in these trials.