Effects of replacing rye silage with mixed rye-vetch-straw silage on feed intake, milk production, digestion processes, and blood metabolites in dairy cows

Mixed silage of whole catch crops-crops grown between 2 main crops-and straw might be an alternative forage source for dairy cattle in times of forage shortage but is still understudied. This research sought to evaluate the effects of feeding mixed rye-vetch-straw silage (RVSS) in replacement of whole crop rye silage on feed intake, ECM yield, milk composition, nutrient digestibility, and metabolic variables of dairy cows. The study was a crossover trial with 10 Holstein and 4 Simmental cows (average of 593 kg BW and 53 DIM at the start of the trial) tested in 2 experimental runs of 4 wk each, whereby the last 2 wk were used for the measurements. The cows were randomly allocated to one of the 2 diets differing only in the major forage source, either RVSS (RVSS treatment) or a pure rye silage (RS treatment) as the control. The diets were fed as partial mixed rations consisting on a DM basis of 43.8% RVSS or RS, 14.6% corn silage, 14.6% meadow hay, and 27.0% concentrate mixture. The cows were additionally supplemented with 5 kg of concentrate per day. Data showed that feeding the RVSS diet tended to decrease the DMI without affecting performance (mean ECM yield: 28.4 kg/d) or the mean BW during the sampling period. Feeding the RVSS diet tended to increase dairy feed efficiency (kg ECM/kg DMI), likely due to the higher apparent total-tract OM digestibility of the RVSS diet compared with the RS diet. Furthermore, cows fed the RVSS diet spent significantly more time on rumination per kilogram of intake of physically effective NDF. Diet did not affect the concentration of glucose, BHB, urea, total protein, albumin, triglycerides, cholesterol, liver enzymes, or macro minerals in blood. Neither of the diets affected the concentration or proportion of short-chain fatty acids in the rumen fluid and feces. In conclusion, the mixed silage of catch crop and straw holds potential to replace traditional rye silage in the feeding of dairy cows yielding up to 30 kg of ECM per day. Feeding the RVSS diet enhanced the apparent total-tract OM digestibility and rumination index, without any negative effects on ECM yield, milk composition, BW, ruminal and fecal VFA concentration, or key blood variables. Future research may evaluate the potential of mixed silages of catch crops and straw in the feeding of high-producing dairy cows as a viable option to overcome shortages in forage production. Mixed silage of whole catch crops-crops grown between 2 main crops-and straw might be an alternative forage source for dairy cattle in times of forage shortage but is still understudied. This research sought to evaluate the effects of feeding mixed rye-vetch-straw silage (RVSS) in replacement of whole crop rye silage on feed intake, ECM yield, milk composition, nutrient digestibility, and metabolic variables of dairy cows. The study was a crossover trial with 10 Holstein and 4 Simmental cows (average of 593 kg BW and 53 DIM at the start of the trial) tested in 2 experimental runs of 4 wk each, whereby the last 2 wk were used for the measurements. The cows were randomly allocated to one of the 2 diets differing only in the major forage source, either RVSS (RVSS treatment) or a pure rye silage (RS treatment) as the control. The diets were fed as partial mixed rations consisting on a DM basis of 43.8% RVSS or RS, 14.6% corn silage, 14.6% meadow hay, and 27.0% concentrate mixture. The cows were additionally supplemented with 5 kg of concentrate per day. Data showed that feeding the RVSS diet tended to decrease the DMI without affecting performance (mean ECM yield: 28.4 kg/d) or the mean BW during the sampling period. Feeding the RVSS diet tended to increase dairy feed efficiency (kg ECM/kg DMI), likely due to the higher apparent total-tract OM digestibility of the RVSS diet compared with the RS diet. Furthermore, cows fed the RVSS diet spent significantly more time on rumination per kilogram of intake of physically effective NDF. Diet did not affect the concentration of glucose, BHB, urea, total protein, albumin, triglycerides, cholesterol, liver enzymes, or macro minerals in blood. Neither of the diets affected the concentration or proportion of short-chain fatty acids in the rumen fluid and feces. In conclusion, the mixed silage of catch crop and straw holds potential to replace traditional rye silage in the feeding of dairy cows yielding up to 30 kg of ECM per day. Feeding the RVSS diet enhanced the apparent total-tract OM digestibility and rumination index, without any negative effects on ECM yield, milk composition, BW, ruminal and fecal VFA concentration, or key blood variables. Future research may evaluate the potential of mixed silages of catch crops and straw in the feeding of high-producing dairy cows as a viable option to overcome shortages in forage production.© 2025, The Authors. Published by Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

• Improving the resilience of local forage production in cattle feeding by upgrading drought-impaired forage and optimizing regional forage resources.

Höhere Bundeslehr- und Forschungsanstalt Raumberg-Gumpenstein