F. Hassanat

Assessment of the effect of condensed (acacia and quebracho) and hydrolysable (chestnut and valonea) tannins on rumen fermentation and methane production in vitro

BACKGROUND Tannins added to animal diets may have a positive effect on energy and protein utilisation in the rumen. The objective of this study was to examine the impact of different sources and concentrations (20, 50, 100, 150 and 200 g kg⁻¹ dry matter (DM)) of condensed (acacia and quebracho) and hydrolysable (chestnut and valonea) tannins on rumen microbial fermentation in vitro. The experiment also included a negative control with no tannins (control) and a positive control with monensin (10 mg L⁻¹). RESULTS In vitro gas production and total volatile fatty acid (VFA) concentration decreased as tannin concentration increased. Addition of acacia, chestnut or valonea tannins at ≥ 50 g kg⁻¹ or quebracho tannins at ≥ 100 g kg⁻¹ resulted in a decrease (up to 40%) in methane (CH₄) production compared with the control. Valonea tannins were the only tannin source that reduced (-11%) CH₄ production at 50 g kg⁻¹ without affecting VFA concentration. Tannin treatments reduced ammonia (NH₃) and branched-chain VFA concentrations, indicating a reduction in ruminal protein degradation. Monensin reduced CH₄ production (-37%) and NH₃ concentration (-20%) without affecting total VFA concentration. CONCLUSION Supplying acacia, chestnut or valonea tannins at 50 g kg⁻¹ has the potential to reduce CH₄ production and ruminal protein degradation with minimum detrimental effects on efficiency of ruminal fermentation.

Linseed oil supplementation to dairy cows fed diets based on red clover silage or corn silage: Effects on methane production, rumen fermentation, nutrient digestibility, N balance, and milk production

The objective of this study was to examine the effect of linseed oil (LO) supplementation to red clover silage (RCS)- or corn silage (CS)-based diets on enteric CH4 emissions, ruminal fermentation characteristics, nutrient digestibility, N balance, and milk production. Twelve rumen-cannulated lactating cows were used in a replicated 4×4 Latin square design (35-d periods) with a 2×2 factorial arrangement of treatments. Cows were fed (ad libitum) RCS- or CS-based diets [forage:concentrate ratio 60:40; dry matter (DM) basis] without or with LO (4% of DM). Supplementation of LO to the RCS-based diet reduced enteric CH4 production (-9%) and CH4 energy losses (-11%) with no adverse effects on DM intake, digestion, ruminal fermentation characteristics, protozoa numbers, or milk production. The addition of LO to the CS-based diet caused a greater decrease in CH4 production (-26%) and CH4 energy losses (-23%) but was associated with a reduction in DM intake, total-tract fiber digestibility, protozoa numbers, acetate:propionate ratio, and energy-corrected milk yield. Urinary N excretion (g/d) decreased with LO supplementation to RCS- and CS-based diets, suggesting reduced potential of N2O emissions. Results from this study show that the depressive effect of LO supplementation on enteric CH4 production is more pronounced with the CS- than with the RCS-based diet. However, because of reduced digestibility with the CS-based diet, the reduction in enteric CH4 production may be offset by higher CH4 emissions from manure storage. Thus, the type of forage of the basal diet should be taken into consideration when using fat supplementation as a dietary strategy to reduce enteric CH4 production from dairy cows.

Prediction of enteric methane emissions from Holstein dairy cows fed various forage sources

Milk fatty acid (FA) profile has been previously used as a predictor of enteric CH4 output in dairy cows fed diets supplemented with plant oils, which can potentially impact ruminal fermentation. The objective of this study was to investigate the relationships between milk FA and enteric CH4 emissions in lactating dairy cows fed different types of forages in the context of commonly fed diets. A total of 81 observations from three separate 3×3 Latin square design (32-day periods) experiments including a total of 27 lactating cows (96±27 days in milk; mean±SD) were used. Dietary forages were included at 60% of ration dry matter and were as follows: (1) 100% corn silage, (2) 100% alfalfa silage, (3) 100% barley silage, (4) 100% timothy silage, (5) 50:50 mix of corn and alfalfa silages, (6) 50:50 mix of barley and corn silages and (7) 50:50 mix of timothy and alfalfa silages. Enteric CH4 output was measured using respiration chambers during 3 consecutive days. Milk was sampled during the last 7 days of each period and analyzed for components and FA profile. Test variables included dry matter intake (DMI; kg/day), NDF (%), ether extract (%), milk yield (kg/day), milk components (%) and individual milk FA (% of total FA). Candidate multivariate models were obtained using the Least Absolute Shrinkage and Selection Operator and Least-Angle Regression methods based on the Schwarz Bayesian Criterion. Data were then fitted into a random regression using the MIXED procedure including the random effects of cow, period and study. A positive correlation was observed between CH4 and DMI (r=0.59, P0.19). Milk FA profile and DMI can be used to predict CH4 emissions in dairy cows across a wide range of dietary forage sources.

Methane production, nutrient digestion, ruminal fermentation, N balance, and milk production of cows fed timothy silage- or alfalfa silage-based diets

The objective of this study was to investigate the effects of changing forage source in dairy cow diets from timothy silage (TS) to alfalfa silage (AS) on enteric CH₄ emissions, ruminal fermentation characteristics, digestion, milk production, and N balance. Nine ruminally cannulated lactating cows were used in a replicated 3 × 3 Latin square design (32-d period) and fed (ad libitum) a total mixed ration (TMR; forage:concentrate ratio of 60:40, dry matter basis), with the forage portion consisting of either TS (0% AS; 0% AS and 54.4% TS in the TMR), a 50:50 mixture of both silages (50% AS; 27.2% AS and 27.2% TS in the TMR), or AS (100% AS; 54.4% AS and 0% TS in the TMR). Compared with TS, AS contained less (36.9 vs. 52.1%) neutral detergent fiber but more (20.5 vs. 13.6%) crude protein (CP). In sacco 24-h ruminal degradability of organic matter (OM) was higher for AS than for TS (73.5 vs. 66.9%). Replacement of TS with AS in the diet entailed increasing proportions of corn grain and bypass protein supplement at the expense of soybean meal. As the dietary proportion of AS increased, CP and starch concentrations increased, whereas fiber content declined in the TMR. Dry matter intake increased linearly with increasing AS proportions in the diet. Apparent total-tract digestibility of OM and gross energy remained unaffected, whereas CP digestibility increased linearly and that of fiber decreased linearly with increasing inclusion of AS in the diet. The acetate-to-propionate ratio was not affected, whereas ruminal concentration of ammonia (NH₃) and molar proportion of branched-chain VFA increased as the proportion of AS in the diet increased. Daily CH₄ emissions tended to increase (476, 483, and 491 g/d for cows fed 0% AS, 50% AS, and 100% AS, respectively) linearly as cows were fed increasing proportions of AS. Methane production adjusted for dry matter intake (average=19.8 g/kg) or gross energy intake (average=5.83%) was not affected by increasing AS inclusion in the diet. When expressed on a fat-corrected milk or energy-corrected milk yield basis, CH₄ production increased linearly with increasing AS dietary proportion. Urinary N excretion (g/d) increased linearly when cows were fed increasing amounts of AS in the diet, suggesting a potential for higher nitrous oxide (N₂O) and NH₃ emissions. Efficiency of dietary N use for milk protein secretion (g of milk N/g of N intake) declined with the inclusion of AS in the diet. Despite marked differences in chemical composition and ruminal degradability, under the conditions of this study, replacing TS with AS in dairy cow diets was not effective in reducing CH₄ energy losses.

Methane production, ruminal fermentation characteristics, nutrient digestibility, nitrogen excretion, and milk production of dairy cows fed conventional or brown midrib corn silage

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.

Effects of Adding Corn Dried Distiller Grains with Solubles (DDGS) to the Dairy Cow Diet and Effects of Bedding in Dairy Cow Slurry on Fugitive Methane Emissions.

Simple Summary The objectives of this experiment were to investigate the effects of adding corn DDGS to the dairy cow diet as well as the bedding types (wood shavings, straw or peat moss) on manure fugitive CH4 emissions. The incorporation of DDGS in the diet has increased manure methane emission by 15% and the use of peat moss as bedding has increased manure methane emission by 27%. Abstract The specific objectives of this experiment were to investigate the effects of adding 10% or 30% corn dried distillers grains with solubles (DDGS) to the dairy cow diet and the effects of bedding type (wood shavings, straw or peat moss) in dairy slurry on fugitive CH4 emissions. The addition of DDGS10 to the dairy cow diet significantly increased (29%) the daily amount of fat excreted in slurry compared to the control diet. The inclusion of DDGS30 in the diet increased the daily amounts of excreted DM, volatile solids (VS), fat, neutral detergent fiber (NDF), acid detergent fiber (ADF) and hemicellulose by 18%, 18%, 70%, 30%, 15% and 53%, respectively, compared to the control diet. During the storage experiment, daily fugitive CH4 emissions showed a significant increase of 15% (p < 0.05) for the slurry resulting from the corn DDGS30 diet. The addition of wood shavings and straw did not have a significant effect on daily fugitive CH4 emissions relative to the control diet, whereas the addition of peat moss caused a significant increase of 27% (p < 0.05) in fugitive CH4 emissions.

Faba bean (Vicia faba) inclusion in dairy cow diets: Effect on nutrient digestion, rumen fermentation, nitrogen utilization, methane production, and milk performance

The objective of this study was to determine the effect of replacing on isonitrogenous and isoenergetic basis soybean meal (SBM) and corn grain with ground or rolled faba bean (FB; Vicia faba major var. Baie-Saint-Paul) in dairy cow diets (17% of diet dry matter) on nutrient digestion, rumen fermentation, N utilization, methane production, and milk performance. For this purpose, 9 lactating cows were used in a replicated 3 × 3 Latin square design (35-d period) and fed (ad libitum) a total mixed ration (forage:concentrate ratio = 59:41 on a dry matter basis). In the concentrate portion, SBM and corn grain (control diet) were completely and partially replaced, respectively, with either ground or rolled FB. Ruminal degradability (in sacco) of crude protein was higher for ground FB (79.4%) compared with SBM (53.3%) and rolled FB (53.2%). Including FB in the diet did not affect dry matter intake, milk production, and milk composition. Experimental treatment had no effect on total volatile fatty acid concentration, acetate-to-propionate ratio, and protozoa numbers. Compared with cows fed the control diet, ruminal NH3 concentration increased and tended to increase for cows fed ground FB and rolled FB, respectively; however, we found no difference in ruminal NH3 concentration between the 2 processed FB. Apparent total-tract digestibility of crude protein was similar between cows fed the control diet and cows fed rolled FB and tended to increase for cows fed ground FB compared with cows fed the control diet. Feeding rolled FB decreased CP digestibility compared with feeding ground FB. Urinary and manure (feces + urine) N excretion (g/d or as a proportion of N intake) were not affected by the inclusion of FB in the diet. Enteric CH4 production was similar among the experimental diets. Results from this study show that including FB (17% of dietary dry matter) at the expense of SBM and corn grain in the diet had no effect on milk production, N excretion, and enteric CH4 production of dairy cows.