Feeding alfalfa- or red clover-grass mixture baleage: Effect on milk yield and composition, ruminal fermentation and microbiota taxa relative abundance, and nutrient utilization in dairy cows

Authors: LANGE, MAICHAL - Consultant; SILVA, LUIZ - University Of New Hampshire; ZAMBON, MAXIMILIANE - Consultant; Soder, Kathy; BRITO, ANDRE - University Of New Hampshire

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2023
Publication Date: 3/20/2024
Citation: Lange, M.J., Silva, L.H., Zambon, M.A., Soder, K.J., Brito, A. 2024. Feeding alfalfa- or red clover-grass mixture baleage: Effect on milk yield and composition, ruminal fermentation and microbiota taxa relative abundance, and nutrient utilization in dairy cows. Journal of Dairy Science. 107(4):2066-2086. https://doi.org/10.3168/jds.2023-23836.
DOI: https://doi.org/10.3168/jds.2023-23836

Interpretive Summary: Red clover forage contains enzymes that break down proteins during the fermentation of fresh forage into silage. This may result in greater nutrient digestibility (and therefore greater milk production in dairy cows) and lower nitrogen concentrations in urine which can be an environmental concern. However, red clover has not been evaluated directly against alfalfa, a similar forage that does not have the same enzymes. While results of this work showed that feeding red clover to lactating dairy cows did generally decrease urinary nitrogen but did not increase milk production, the results were not consistent. Additional research is needed to further determine the efficacy of using red clover silage to improve production efficiency in dairy cows to reduce nitrogen losses to the environment and improve milk production.

Technical Abstract: Red clover contains the enzyme polyphenol oxidase, which is known to mediate reactions that can reduce proteolysis and lipolysis during ensilage. Our goal was to investigate the effect of diets containing baleages harvested from alfalfa- or red clover-grass mixture on production performance, milk fatty acid (FA) profile, plasma concentration of AA, and urinary excretion of N in dairy cows. Two fields were seeded to a mixture of legumes (alfalfa or red clover; 24.7 kg of seeds/ha of each) and 2 companion grasses (meadow fescue and timothy; 4.97 and 2.24 kg/ha, respectively) to produce the baleages used in the experiment. Twenty Jersey cows (18 multiparous and 2 primiparous) averaging (mean ± SD) 148 ± 45.2 days in milk and 483 ± 65.4 kg of body weight in the beginning of the study were used in a randomized complete block design with repeated measures over time. The experiment lasted 9 wk, with a 2 wk covariate period followed by 7 wk of data and sample collection (wk 4 and 7 used in the statistical analyses). Cows were fed diets containing [dry matter (DM) basis] 35% of a concentrate mash and the following forage sources: (1) 65% second and third cut (32.5% each) alfalfa-grass mixture baleages (ALF-GR diet) or (2) 65% second and third-cut baleage (32.5% each) red clover-grass mixture baleages (RC-GR diet). Diets did not affect DM intake, milk yield, and milk fat concentration. In contrast, 4% fat-corrected milk yield decreased and yields of milk fat and energy-corrected milk tended to decrease with feeding RC-GR versus ALF-GR. We observed no changes in the concentrations and yields of milk true protein and lactose. Diet by week interactions were found for milk urea N and plasma urea N concentrations, with both decreasing in cows fed RC-GR in wk 4. Milk proportions of trans-10 18:1 and cis-9, cis-12, cis-15 18:3, as well as total n-6, n-3, branched-chain FA, and 18C FA were all greater in RC-GR compared with ALF-GR. Plasma concentrations of Leu, Phe, and Val increased, and plasma Ile tended to increase in RC-GR versus ALF-GR. Furthermore, diet × week interactions were seen for plasma Arg, His, and Trp concentrations. Cows fed RC-GR had greater plasma His concentration than those fed ALF-GR, particularly during wk 7. While no change between diets was detected for plasma Trp in wk 4 and 7, feeding RC-GR increased the plasma concentration of Arg in wk 7. A diet × week interaction was also observed for the amount of N excreted in urine, which tended to decrease (-24%) in wk 4 in the RC-GR diet but did not change in wk 7. Overall, feeding RC-GR increased the milk proportion of n-3 FA and the plasma concentrations of His, Phe, and individual branched-chain AA. However, elevated concentration of plasma essential AA had no effect on yields of milk and milk true protein.