Enteric methane production, rumen volatile fatty acid concentrations, and milk fatty acid composition in lactating Holstein-Friesian cows fed grass silage- or corn silage-based diets

Abstract

The objective of this study was to determine the effects of replacing grass silage (GS) with corn silage (CS) in dairy cow diets on enteric methane (CH4) production, rumen volatile fatty acid concentrations, and milk fatty acid (FA) composition. A completely randomized block design experiment was conducted with 32 multiparous lactating Holstein-Friesian cows. Four dietary treatments were used, all having a roughage-to-concentrate ratio of 80:20 based on dry matter (DM). The roughage consisted of either 100% GS, 67% GS and 33% CS, 33% GS and 67% CS, or 100% CS (all DM basis). Feed intake was restricted (95% of ad libitum DM intake) to avoid confounding effects of DM intake on CH4 production. Nutrient intake, apparent digestibility, milk production and composition, nitrogen (N) and energy balance, and CH4 production were measured during a 5-d period in climate respiration chambers after adaptation to the diet for 12 d. Increasing CS proportion linearly decreased neutral detergent fiber and crude protein intake and linearly increased starch intake. Milk production and milk fat content (on average 23.4 kg/d and 4.68%, respectively) were not affected by increasing CS inclusion, whereas milk protein content increased quadratically. Rumen variables were unaffected by increasing CS inclusion, except the molar proportion of butyrate, which increased linearly. Methane production (expressed as grams per day, grams per kilogram of fat- and protein-corrected milk, and as a percent of gross energy intake) decreased quadratically with increasing CS inclusion, and decreased linearly when expressed as grams of CH4 per kilogram of DM intake. In comparison with 100% GS, CH4 production was 11 and 8% reduced for the 100% CS diet when expressed per unit of DM intake and per unit fat- and protein-corrected milk, respectively. Nitrogen efficiency increased linearly with increased inclusion of CS. The concentration of trans C18:1 FA, C18:1 cis-12, and total CLA increased quadratically, and iso C16:0, C18:1 cis-13, and C18:2n-6 increased linearly, whereas the concentration of C15:0, iso C15:0, C17:0, and C18:3n-3 decreased linearly with increasing inclusion of CS. No differences were found in short- and medium-straight, even-chain FA concentrations, with the exception of C4:0 which increased linearly with increased inclusion of CS. Replacing GS with CS in a common forage-based diet for dairy cattle offers an effective strategy to decrease enteric CH4 production without negatively affecting dairy cow performance, although a critical level of starch in the diet seems to be needed.

Fractionation of carbohydrates and nitrogenous constituents of late-crop corn silages ensiled with different specific masses

“…These results can be explained by the higher quality of corn plants, with more appropriate DM contents than other silage grasses. Importantly, the results obtained by Van Gastelen et al (2015) demonstrate the potential of Brazilian corn silage to simultaneously increase animal efficiency and reduce greenhouse gasses, the latter being a major objective of the 2015 Paris Climate Conference (COP 21). Therefore, it is crucial that Brazil allocate more financial resources to research on the production, handling, and use of conserved forage (silage and hay), as well as on the potential beneficial and deleterious environmental impacts of such processes.…”

“…Van Gastelen et al (2015) analyzed the replacement of corn silage with starchless grass silage on ruminal volatile fatty acid concentration, pH, and methane (CH 4 ) mitigation. The authors reported that increasing proportions of corn silage resulted in linear decreases in NDF intake (P < 0.001) and CP (P = 0.002) and linearly increases in starch intake (P < 0.001), whereas CH 4 emission decreased in a quadratic manner (P < 0.001) and decreased linearly (P = 0.010) when expressed as g CH 4 kg -1 DM intake.…”

Effects of nitrogen fertilisation rate and maturity of grass silage on methane emission by lactating dairy cows

“…Each block of six cows was completed within two consecutive periods; cows and treatments were randomly distributed to the CRC and periods. A detailed description of the CRC design and gas measurements was reported by van Gastelen et al (2015). Briefly, in each CRC (volume 35 m 3 ) relative humidity was maintained at 70% and temperature at 16°C.…”

Invited review: Large-scale indirect measurements for enteric methane emissions in dairy cattle: A review of proxies and their potential for use in management and breeding decisions

“…For example, at the animal level, replacing grass or grass silage with corn silage in the diet is a valuable strategy with an immediate effect in reducing GHG emissions (e.g., Beauchemin et al, 2008;Van Gastelen et al, 2015). However, at the farm and chain level, the strategy is not applicable for farms that cannot further reduce their grassland surface because of compliance with the European Union (EU) derogation regulation.…”