Methane production, rumen fermentation, and diet digestibility of Holstein and Jersey dairy cows being divergent in residual feed intake and fed at 2 forage-to-concentrate ratios

Abstract

Improving feed efficiency of dairy cows through breeding is expected to reduce enteric methane production per unit of milk produced. This study examined the effect of 2 forage-to-concentrate ratios on methane production, rumen fermentation, and nutrient digestibility in Holstein and Jersey dairy cows divergent in residual feed intake (RFI). Before experimental onset, RFI was estimated using a random regression model on phenotypic herd data. Ten lactating Holstein and 10 lactating Jersey cows were extracted from the herd and allocated to a high or low pre-experimental RFI group of 5 animals each within breed. Cows were fed ad libitum with total mixed rations either low (LC) or high (HC) in concentrates during 3 periods in a crossover design with a back-cross and staggered approach. Forage-to-concentrate ratio was 68:32 for LC and 39:61 for HC. Cows adapted to the diets in 12 to 24 d and feces were subsequently collected on 2 d. Afterward, gas exchange was measured in respiration chambers and rumen liquid was collected once after cows exited the chambers. Pre-experimental RFI was included in the statistical analysis as a class (low and high RFI) or continuous variable. Methane per kilogram of dry matter intake (DMI) was lower for Holsteins than Jerseys and the response to increased concentrate level was more pronounced for Holsteins than Jerseys (27.2 vs.13.8%); a similar pattern was found for the acetate:propionate ratio. However, methane production per kilogram of energy-corrected milk (ECM) was unaffected by breed. Further, total-tract digestibility of neutral detergent fiber was higher for Jerseys than Holsteins. For RFI as a class variable, DMI, methane production regardless of the expression, and digestibility were unaffected by RFI. For RFI as a continuous variable, DMI was lower and methane per kilogram of DMI was higher for cows with negative (efficient) than positive (inefficient) RFI values, and neutral detergent fiber digestibility was higher for Holsteins with negative than positive RFI values, but not for Jerseys. Daily methane production and methane per kilogram of ECM were unaffected by RFI. In conclusion, methane per kilogram of DMI of Jerseys was lowered to a smaller extent in response to the HC diet than of Holsteins. When pre-experimental RFI was used as a continuous variable, higher methane per kilogram of DMI was found for cows with negative RFI than positive RFI values, but not for methane per kilogram of ECM. These findings call for validation in larger studies.

Volatile Fatty Acids in Ruminal Fluid Can Be Used to Predict Methane Yield of Dairy Cows

“…The components of MSEP were 0.62 for error-of-central-tendency, 0.20 for error-due-to-regression, and 8.1 for error-of-disturbance. Similar results were obtained for Equations (3) and 7 4, and (c) Equation 7showing the observed methane yield against equation-predicted methane yield, for 32 individual [6], (open circles) and 67 treatment means from 16 previously published experiments [14,[36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] (closed circles) with 1:1 line of agreement (dashed).…”

“…Subsequent work by Smith et al [60], in which ruminal fluid was sampled 3 h after the start of feeding, reported a weak negative correlation between methane yield and individual VFA proportions. 4, and (c) Equation 7showing the observed methane yield against equation-predicted methane yield, for 32 individual [6], (open circles) and 67 treatment means from 16 previously published experiments [14,[36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] (closed circles) with 1:1 line of agreement (dashed).…”

Methane and Carbon Dioxide Emission of Beef Heifers in Relation with Growth and Feed Efficiency

“…In the review of Richardson and Herd [41], digestibility was assumed to account for 10% of the variation in RFI on average in beef cattle, while Lovendahl et al [42], in their review of dairy cattle, concluded that between-cow variation in digestibility alone was too small to explain the observed variation in feed efficiency. Nonetheless, higher digestibility of DM or NDF was found in low-RFI as compared to high-RFI cattle in the studies of McDonnell et al [15] and Oliveira et al [17] with beef cattle and Olijhoek et al [43] with dairy Holstein cows. On the other hand, no significant difference was observed in the studies of Nkrumah et al [7], Fitzsimons et al [12] and Fitzsimons et al [44] with beef cattle and Olijhoek et al [43] with dairy Jersey cows and Fischer et al [45] with dairy Holstein cows.…”

“…Nonetheless, higher digestibility of DM or NDF was found in low-RFI as compared to high-RFI cattle in the studies of McDonnell et al [15] and Oliveira et al [17] with beef cattle and Olijhoek et al [43] with dairy Holstein cows. On the other hand, no significant difference was observed in the studies of Nkrumah et al [7], Fitzsimons et al [12] and Fitzsimons et al [44] with beef cattle and Olijhoek et al [43] with dairy Jersey cows and Fischer et al [45] with dairy Holstein cows. Interestingly, a higher digestibility and a higher methane yield were observed in low-RFI beef heifers tested with three different diets by McDonnell et al [15] and in low-RFI beef Nellore tested in feedlot by Oliveira et al [17].…”

Profiles of Odd- and Branched-Chain Fatty Acids and Their Correlations With Rumen Fermentation Parameters, Microbial Protein Synthesis and Bacterial Populations Based on Pure Carbohydrate Incubation in Vitro

“…As for the branched-chain fatty acids, the iso-fatty acids are produced from isobutyrate and isovalerate while antiso-fatty acids are originated from 2-methybutyrate in ruminants, as summarized by Vlaeminck et al [11]. The generation of these short chain fatty acids is not only in uenced by dietary strategy [3,26], but also highly depending on ruminal environment and physiological conditions of cows [27]. Indeed, studies regarding ruminal OBCFA productions in cows fed rations with different ratios of forage and concentrate have shown contrasting results.…”