C. Benchaar

Mitigation strategies to reduce enteric methane emissions from dairy cows: Update review

Enteric methane (CH4) emission is a major contributor to Canadian greenhouse gas emissions, and also a loss of feed energy during production. The objective of this paper is to provide an update on current management practices and new dietary strategies recently proposed to reduce CH4 emissions from ruminants. Existing mitigation strategies for dairy, e.g., the addition of ionophores, fats, use of high-quality forages, and increased use of grains, have been well researched and applied. These nutritional changes reduce CH4 emissions by manipulating ruminal fermentation, directly inhibiting methanogens and protozoa, or by diverting hydrogen ions away from methanogens. Current literature has identified new CH4 mitigation options. These include the addition of probiotics, acetogens, bacteriocins, archaeal viruses, organic acids, plant extracts (e.g., essential oils) to the diet, as well as immunization, and genetic selection of cows. These new strategies are promising, but more research is needed to validate t...

Crushed sunflower, flax, or canola seeds in lactating dairy cow diets: effects on methane production, rumen fermentation, and milk production.

The objective of this study was to investigate the potential of reducing enteric methane production from dairy cows by incorporating into the diet various sources of long-chain FA varying in their degree of saturation and ruminal availability. The experiment was conducted as a crossover design with 16 lactating dairy cows maintained in 2 groups and fed 4 dietary treatments in four 28-d periods. Eight ruminally cannulated primiparous cows (96 +/- 18 d in milk) were assigned to group 1 and 8 multiparous cows (130 +/- 31 d in milk) were assigned to group 2. The dietary treatments were: 1) a commercial source of calcium salts of long-chain fatty acids (CTL), 2) crushed sunflower seeds (SS), 3) crushed flaxseed (FS), and 4) crushed canola seed (CS). The oilseeds added 3.1 to 4.2% fat to the diet (DM basis). All 3 oilseed treatments decreased methane production (g/d) by an average of 13%. When corrected for differences in dry matter intake (DMI), compared with CTL, methane production (g/kg of DM intake) was decreased by feeding FS (-18%) or CS (-16%) and was only numerically decreased (-10%) by feeding SS. However, compared with the CTL, feeding SS or FS lowered digestible DMI by 16 and 9%, respectively, because of lowered digestibility. Thus, only CS lowered methane per unit of digestible DM intake. Feeding SS and CS decreased rumen protozoal counts, but there were no treatment effects on mean ruminal pH or total volatile fatty acid concentration. Milk efficiency (3.5% fat corrected milk/DMI), milk yield, and component yield and concentrations were not affected by oilseed treatments. The study shows that adding sources of long-chain fatty acids to the diet in the form of processed oilseeds can be an effective means of reducing methane emissions. However, for some oilseeds such as SS or FS, the reduction in methane can be at the expense of diet digestibility. The use of crushed CS offers a means of mitigating methane without negatively affecting diet digestibility, and hence, milk production.

Evaluation of dietary strategies to reduce methane production in ruminants: A modelling approach

The objective of this study was to use the modelling approach to assess the effectiveness of different existing nutritional strategies to reduce methane production from ruminants. For this purpose, a modified version of a mechanistic and dynamic model of rumen digestion was used. Simulated strategies included: dry matter intake (DMI), forage to concentrate ratio, nature of concentrate (fibrous vs. starchy concentrate), type of starch (slowly vs. rapidly degraded), forage species (legume vs. grass), forage maturity, forage preservation method (dried vs. ensiled), forage processing, and upgrading and supplementation of poor quality forages (straw). This study showed that mathematical modelling is a valuable tool to evaluate the impact of a given dietary manipulation not only on methanogenesis but also on the metabolism of the whole rumen system. Depending on the nature of the intervention, methane production can be reduced by 10 to 40%. Increasing DMI and the proportion of concentrate in the diet reduced me...

Feeding saponin-containing Yucca schidigera and Quillaja saponaria to decrease enteric methane production in dairy cows.

An experiment was conducted in vitro to determine whether the addition of saponin-containing Yucca schidigera or Quillaja saponaria reduces methane production without impairing ruminal fermentation or fiber digestion. A slightly lower dose of saponin was then fed to lactating dairy cows to evaluate effects on ruminal fermentation, methane production, total-tract nutrient digestibility, and milk production and composition. A 24-h batch culture in vitro incubation was conducted in a completely randomized design with a control (no additive, CON) and 3 doses of either saponin source [15, 30, and 45 g/kg of substrate dry matter (DM)] using buffered ruminal fluid from 3 dairy cows. The in vivo study was conducted as a crossover design with 2 groups of cows, 3 treatments, and three 28-d periods. Six ruminally cannulated cows were used in group 1 and 6 intact cows in group 2 (627 +/- 55 kg of body weight and 155 +/- 28 d in milk). The treatments were 1) early lactation total mixed ration, no additive (control; CON); 2) CON diet supplemented with whole-plant Y. schidigera powder at 10 g/kg of DM (YS); and 3) CON diet supplemented with whole-plant Q. saponaria powder at 10 g/kg of DM (QS). Methane production was measured in environmental chambers and with the sulfur hexafluoride (SF(6)) tracer technique. In vitro, increasing levels of both saponin sources decreased methane concentration in the headspace and increased the proportion of propionate in the buffered rumen fluid. Concentration of ammonia-N, acetate proportion, and the acetate:propionate ratio in the buffered rumen fluid as well as 24-h digestible neutral detergent fiber were reduced compared with the CON treatment. Medium and high saponin levels decreased DM digestibility compared with the CON treatment. A lower feeding rate of both saponin sources (10 g/kg of DM) was used in vivo in an attempt to avoid potentially negative effects of higher saponin levels on feed digestibility. Feeding saponin did not affect milk production, total-tract nutrient digestibility, rumen fermentation, or methane production. However, DM intake was greater for cows fed YS and QS than for CON cows, with a tendency for greater DM intake for cows fed YS compared with those fed QS. Consequently, efficiency of milk production (kg of milk/kg of DM intake) was lower for cows fed saponin compared with controls. The results show that although saponin from Y. schidigera and Q. saponaria lowered methane production in vitro, the reduction was largely due to reduced ruminal fermentation and feed digestion. Feeding a lower dose of saponin to lactating dairy cows avoided potentially negative effects on ruminal fermentation and feed digestion, but methane production was not reduced. Lower efficiency of milk production of cows fed saponin, and potential reductions in feed digestion at high supplementation rates may make saponin supplements an unattractive option for lowering methane production in vivo.

Digestion, ruminal fermentation, ciliate protozoal populations, and milk production from dairy cows fed cinnamaldehyde, quebracho condensed tannin, or Yucca schidigera saponin extracts.

Four ruminally cannulated lactating cows were used in a 4 x 4 Latin square design (28-d periods) to determine the effects of cinnamaldehyde (CIN; 1 g/cow per day), condensed tannins from quebracho trees (QCT, containing 70% tannins, 150 g/cow per day), and saponins from Yucca schidigera extract (YSE, containing 10% saponins; 60 g/cow per day) on digestion, ruminal fermentation characteristics, protozoal populations, and milk production. Intake of dry matter was not affected by the addition of CIN or QCT, but cows fed YSE had lesser intake than cows fed the control diet (21.8 vs. 23.2 kg/d). Apparent total-tract digestibilities of dry matter, organic matter, crude protein, neutral detergent fiber, and acid detergent fiber were unaffected by dietary treatments. Supplementation with CIN, QTE, or YSE did not affect in situ ruminal degradation of soybean meal, grass silage, or corn grain. Ruminal pH (6.67), total volatile fatty acid concentration (135 mM), and molar proportions (mol/100 mol of total volatile fatty acid) of acetate (65.0), propionate (19.6), and butyrate (11.2) were similar among treatments. Ruminal NH(3)-N concentration was not changed by the addition of CIN and YSE, but tended to decrease in cows fed QCT compared with cows fed the control diet (132 vs. 160 mg/L). Total numbers of ruminal protozoa were not changed by adding CIN, QCT, or YSE in the diet (5.85 log(10)/mL). However, the number of Isotricha was greater in ruminal fluid of cows fed CIN than in ruminal fluid of cows fed the control diet (4.46 vs. 4.23 log(10)/mL). Milk production (33.1 kg/d), milk fat (4.3%), and milk protein (3.5%) remained unchanged between dietary treatments. Results of this study show that under our experimental conditions, supplementing dairy cow diets with CIN, QCT, or YSE had limited effects on digestion, ruminal fermentation characteristics, and protozoal populations. The lack of effects observed in this study suggests that these antimicrobials require administration at greater doses to favorably alter rumen microbial fermentation.

Effects of essential oils on proteolytic, deaminative and methanogenic activities of mixed ruminal bacteria

The objective of this study was to evaluate in vitro the effects of three essential oils (EO) [cinnamon leaf (250 mg L-1), garlic oil (100 and 250 mg L-1), and juniper berry oil (20 mg L-1)] and tw...

Effects of essential oils and their components on in vitro rumen microbial fermentation

The objective of this study was to investigate the effects of essential oils (EO) and essential oil compounds (EOC) on in vitro rumen microbial fermentation. Treatments were: control (no additive), cinnamon leaf oil (400 mg L-1), clove leaf oil (200 mg L-1), sweet orange oil (200 mg L-1), oregano oil (200 mg L-1), thyme oil (200 mg L-1), carvacrol (400 mg L-1), cinnamaldehyde (400 mg L-1), eugenol (800 mg L-1), and thymol (400 mg L-1). Treatments were evaluated using in vitro 24-h batch culture of rumen fluid with a 51:49 forage:concentrate dairy ration [16.7% crude protein (CP), 34.4% neutral detergent fibre (NDF)]. Incubations were conducted in triplicate with gas production (GP) measured at 0, 2, 6, 8, 12, and 24 h, while pH, ammonia (NH3), volatile fatty acid (VFA), in vitro dry matter (IVDMD) and neutral detergent fibre (IVNDFD) digestibilities were determined after 24 h of incubation. Among the EO and EOC evaluated, only the phenolic compounds, carvacrol, thymol, and eugenol affected ruminal ferment...

Effect of pasture type (alfalfa vs. grass) on methane and carbon dioxide production by yearling beef heifers

The objective of this study was to determine effect of pasture type on methane and carbon dioxide production by heifers grazing alfalfa or grass pastures at three sites across western Canada. All pastures were intensively managed so that heifers had ad libitum access to new forage material each day, and pastures were back-fenced to prevent the heifers accessing previously grazed areas. As measured using the sulfur hexafluoride (SF6) tracer technique, total methane production at the Brandon, MB, and Swift Current, SK, sites was unaffected by pasture type (averaging 157.4 g CH4 head-1 d-1), whereas at Lethbridge, AB, heifers grazing alfalfa produced more methane than did those on the grass pasture (162.8 vs. 113.5 g CH4 head-1 d-1; P < 0.05). Calculated with dry matter intake (DMI) estimated by alkane analysis, methane production per unit DMI was 3 9% lower from heifers consuming grass compared with alfalfa (P < 0.001). When intakes were estimated by the Cornell Net Carbohydrate and Protein System (CNCPS) m...

Meta-analysis on the effects of lipid supplementation on methane production in lactating dairy cows

A meta-analysis was conducted to statistically determine the effects of lipid supplementation on methane (CH4) production, milk production, and milk composition of lactating dairy cows. For this purpose, a data base was built using seven scientific publications (25 diets) available in the literature and reporting the effects of lipid supplementation on CH4 production, milk production, and milk composition. Lipid supplementation decreased (P 0.05). Lipid supplementation decreased (P < 0.05) CH4 production by 9%, either expressed as MJ d-1 or as a percentage of gross energy intake (GEI), digestible energy intake (DEI), or metabolizable energy intake (MEI). This reduction was mainly a consequence of a decreased DMI. Key words: Meta-analysis, lipid supplementation, methane, dairy cows, lactating

Cinnamaldehyde in feedlot cattle diets: Intake, growth performance, carcass characteristics, and blood metabolites

Cinnamaldehyde (CIN), a natural chemical compound found in the bark of cinnamon trees, can alter rumen fermentation by inhibiting selected ruminal microbes, and consequently, may improve growth performance and feed efficiency of animals. The objective of this study was to evaluate the effects of supplementing the diet of feedlot cattle with CIN on intake, growth performance, carcass characteristics, and blood metabolites. Seventy yearling steers (BW = 390 +/- 25.2 kg) were assigned to a randomized complete block design with 5 treatments: control (no additive), monensin (MO; 330 mg*steer(-1)*d(-1)), and 400, 800, or 1,600 mg of CIN*steer(-1)*d(-1). At the start of the experiment, steers were blocked according to BW and assigned to 14 blocks of 5 cattle, with cattle within block assigned to treatments. The diets consisted of 9% barley silage, 86% dry-rolled barley grain, and 5% supplement (DM basis). Dry matter intake responded quadratically (P = 0.03) to CIN supplementation with 13% more feed consumed for steers fed CIN (mean of 3 CIN levels) compared with those fed control during the first 28 d of the experiment, and with a tendency of 4% increase over the entire experiment. The ADG (kg/d) tended to respond quadratically (P = 0.08) to CIN supplementation during the first 28 d, but was not affected over the entire experiment (112 d). Feed efficiency (G:F) linearly declined (P = 0.03) during the first 28 d with CIN supplementation and was quadratically affected between d 29 to 56 and d 85 to 112 by CIN dose. Supplementation of MO did not affect (P > 0.15) DMI or growth performance at any time during the experiment. Serum NEFA concentrations were reduced (P = 0.05) by 35, 29, 30, and 22%, respectively, on d 56, 84, 112, and overall with CIN supplementation. Concentrations of serum amyloid A were reduced on d 28 by 56, 60, or 56% for 800 mg of CIN, 1,600 mg of CIN, and MO, respectively, compared with control. Plasma concentrations of lipopolysaccharide binding protein were linearly decreased (P = 0.05) with increasing CIN supplementation on d 28. Results indicate that supplementing a feedlot finishing diet with a small dose of CIN ameliorated feed intake during the initial month but had minimal effects on ADG, feed efficiency, and carcass traits over the entire experiment. Including CIN in the diet of feedlot cattle, particularly early in the feeding period, may help promote intake and reduce the effects of stress.