Methane production, ruminal fermentation characteristics, nutrient digestibility, nitrogen excretion, and milk production of dairy cows fed conventional or brown midrib corn silage
Hassanat, F., Gervais, R., Benchaar, C. (2017). Methane production, ruminal fermentation characteristics, nutrient digestibility, nitrogen excretion, and milk production of dairy cows fed conventional or brown midrib corn silage. Journal of Dairy Science (JDS), [online] 100(4), 2625-2636. http://dx.doi.org/10.3168/jds.2016-11862
Plain language summary
The effect of replacing conventional corn silage in the diet of dairy cows with brown midrib corn silage (lower lignin content and higher ruminal fibre degradability) on enteric methane production and performance of dairy cows was investigated in this study. Feeding brown midrib corn silage increased dry matter intake and milk production compared to feeding conventional corn silage, without affecting daily enteric methane emissions (g/d). As a result, methane energy losses and the amount of methane emitted per kilogram of milk were lower when cows were fed brown midrib corn silage instead of conventional corn silage. Nitrogen excretion in manure decreased and shifted from urine to feces when brown midrib corn silage replaced conventional corn silage in the diet of dairy cows. Results from this study show that improving fiber quality of corn silage by using the brown midrib cultivar represents an option to mitigate enteric methane emissions and potential nitrogen volatilisation from manure.
The objective of this study was to examine the effect of replacing conventional corn silage (CCS) with brown midrib corn silage (BMCS) in dairy cow diets on enteric CH4 emission, nutrient intake, digestibility, ruminal fermentation characteristics, milk production, and N excretion. Sixteen rumen-cannulated lactating cows used in a crossover design (35-d periods) were fed (ad libitum) a total mixed ration (forage:concentrate ratio = 65:35, dry matter basis) based (59% dry matter) on either CCS or BMCS. Dry matter intake and milk yield increased when cows were fed BMCS instead of CCS. Of the milk components, only milk fat content slightly decreased when cows were fed the BMCS-based diet compared with when fed the CCS-based diet (3.81 vs. 3.92%). Compared with CCS, feeding BMCS to cows increased yields of milk protein and milk fat. Ruminal pH, protozoa numbers, total VFA concentration, and molar proportions of acetate and propionate were similar between cows fed BMCS and those fed CCS. Daily enteric CH4 emission (g/d) was unaffected by dietary treatments, but CH4 production expressed as a proportion of gross energy intake or on milk yield basis was lower for cows fed the BMCS-based diet than for cows fed the CCS-based diet. A decline in manure N excretion and a shift in N excretion from urine to feces were observed when BMCS replaced CCS in the diet, suggesting reduced potential of manure N volatilization. Results from this study show that improving fiber quality of corn silage in dairy cow diets through using brown midrib trait cultivar can reduce enteric CH4 emissions as well as potential emissions of NH3 and N2O from manure. However, CH4 emissions during manure storage may increase due to excretion of degradable OM when BMCS diet is fed, which merits further investigation.