Partially replacing baleage with grazed forage canola in a component feeding system: Effects on production performance, enteric methane emissions, and nutrient utilization in dairy cows

Authors: SILVA, LUIS - University Of New Hampshire; ZANG, YU - University Of New Hampshire; GHELICHKHAN, MOHAMMAD - University Of New Hampshire; DILLARD, LEANNE - Auburn University; Soder, Kathy

Submitted to: Animals
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/10/2025
Publication Date: 6/18/2025
Citation: Silva, L.H., Zang, Y., Ghelichkhan, M., Dillard, L.S., Soder, K.J. 2025. Partially replacing baleage with grazed forage canola in a component feeding system: Effects on production performance, enteric methane emissions, and nutrient utilization in dairy cows. Animals. 19(8):101583. https://doi.org/10.1016/j.animal.2025.101583.
DOI: https://doi.org/10.1016/j.animal.2025.101583

Interpretive Summary: Forage canola is an annual forage crop with high nutritional value and yield that has the potential to extend the grazing season for grazing dairy herds. However, canola may cause digestive upset in lactating dairy cows that could impact health and productivity. Results of this study showed that replacing 50% of an alfalfa silage diet with canola forage fed to lactating dairy cows improved nutrient digestibility by 10-15% and decreased enteric methane production by 14%. However, milk production decreased by 6% despite the extra available nutrients. This suggests that lactating dairy cows fed canola may have partitioned the extra energy into body fat accumulation rather than producing more milk.

Technical Abstract: Forage canola is an annual crop with high nutritive value and potential to extend the grazing period throughout the fall season. We aimed to evaluate the effect of partially replacing alfalfa-grass mix baleage with grazed forage canola on milk yield and composition, apparent total-tract digestibility of nutrients, ruminal fermentation, and nutrient utilization in dairy cows. Twelve multiparous Jersey cows averaging (mean ± SD) 131 ± 63 DIM and 462 ± 26 kg of BW and 6 primiparous Jersey cows averaging 175 ± 64 DIM and 418 ± 38 kg of BW were used in the study. Cows were blocked in pairs by parity, milk yield, and DIM, and within pair, randomly assigned to 1 of 2 treatments formulated (DM basis) as follows: 1) 60% alfalfa-grass mix baleage, 38% concentrate pellet, and 2% roasted soybean (control = CON), and 2) 30% alfalfa-grass mix baleage, 30% grazed forage canola, 38% concentrate pellet, and 2% roasted soybean (forage canola = CAN). Cows in the CAN treatment had access to the forage canola pasture after the afternoon milking at 17000 h. The experiment consisted of a 2-wk covariate period and a 5-wk experimental period with samples collection during wk 3 and wk 5 in a randomized block design with repeated measurements. Although total DMI was greater in cows fed CAN than CON, milk yield decreased with feeding CAN. The concentrations of milk fat and lactose and yields of milk fat and true protein were not affected by treatments. Contrarily, the concentration of milk true protein, milk lactose yield, feed (milk yield/DMI) and milk N efficiency (milk N/N intake), ruminal pH and molar proportion of propionate, milk proportion of n-6 fatty acids, and enteric CH4 emissions all decreased in CAN compared with CON. In addition, milk I concentration and yield were both reduced in CAN versus CON cows due to decreased transfer of feed I to milk I. Treatment by week interactions were observed for the concentrations of MUN, plasma urea N, and ruminal NH3-N, as well as urinary excretion of urea N (g/d and % of total urinary N excretion), ruminal molar proportion of butyrate, and milk proportion of n-3 fatty acids. For all these variables, values were greater with feeding CAN versus CON, but the magnitude of treatments differences varied from wk 3 to wk 5. A treatment by week interaction was also detected for the ruminal molar proportion of acetate, which was lower in CAN versus CON cows but it decreased more pronouncedly in CAN than CON diet from wk 3 to wk 5. Whereas the intake of digestible energy, metabolizable energy (ME), and NEL, tissue energy, and the efficiency of converting digestible energy into ME and ME into NEL increased in CAN versus CON cows, the efficiency of converting of ME into milk energy decreased in the CAN diet. Overall, the CAN diet increased energy intake and nutrient digestibility but elevated energy supply was not accompanied by an improvement in milk yield.