A. V. Chaves

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.

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...

Evaluation of triticale dried distillers grains with solubles as a substitute for barley grain and barley silage in feedlot finishing diets

The objective of this study was to assess the value of triticale dried distillers grains with solubles (DDGS) as a replacement for barley silage in addition to a portion of the dry-rolled barley (DRB) in a grain-based feedlot finishing diet. The trial used 160 crossbred yearling steers: 144 noncannulated (478 +/- 84 kg) in a complete randomized design, and 16 ruminally cannulated (494 +/- 50 kg) in a replicated 4 x 4 Latin square design. The noncannulated steers were assigned to 8 standard pens (10 per pen) and 8 pens equipped with the GrowSafe system (GrowSafe Systems Ltd., Airdrie, Alberta, Canada; 8 per pen). The cannulated steers were placed (2 per pen) in the 8 GrowSafe pens and moved between pens at 28-d intervals. Each of 4 experimental diets was fed in 2 standard and 2 GrowSafe pens. The diets contained (DM basis) 1) 85% DRB and 10% barley silage (CON); 2) 65% DRB, 20% triticale DDGS, and 10% barley silage (D-10S), 3) 65% DRB, 25% triticale DDGS, and 5% barley silage, and 4) 65% DRB, 30% triticale DDGS, and no barley silage. Supplement (5% of dietary DM) was included in all diets. Ruminal pH was measured over four 7-d periods using indwelling electrodes. Replacing barley silage with triticale DDGS linearly decreased mean ruminal pH (P = 0.006), linearly increased duration (P = 0.006 and P = 0.01) and area under the curve (P = 0.02 and P = 0.05) below pH 5.5 and 5.2, and linearly increased the frequency of subacute (P = 0.005) and acute (P = 0.05) bouts of ruminal acidosis. Variation in mean ruminal pH decreased (P = 0.008) in steers fed D-10S compared with CON. Similarly, variation in DMI was less for steers fed triticale DDGS compared with CON. Steers fed D-10S tended to have greater DMI (P = 0.08) but similar ADG and G:F compared with CON steers. Replacing barley silage with triticale DDGS tended to linearly decrease DMI (P = 0.10) and increase (P = 0.06) G:F. Compared with CON, steers fed D-10S tended to have greater backfat thickness (P = 0.10) and decreased dressing percentage (P = 0.06), ribeye area (P = 0.10), and meat yield (P = 0.06). Severity and number of abscessed livers was greater (P = 0.006) in steers fed D-10S compared with those fed CON. Although mean ruminal pH decreased as barley silage was replaced with triticale DDGS, the trend for improved growth suggests that reduced ruminal pH did not affect animal performance. Triticale DDGS can be substituted for barley silage in finishing diets in addition to a portion of barley grain without affecting growth performance or carcass quality, but it is recommended that an antimicrobial be included in the diet to reduce liver abscesses.

Methane Production of Different Forages in In vitro Ruminal Fermentation.

An in vitro rumen batch culture study was completed to compare effects of common grasses, leguminous shrubs and non-leguminous shrubs used for livestock grazing in Australia and Ghana on CH4 production and fermentation characteristics. Grass species included Andropodon gayanus, Brachiaria ruziziensis and Pennisetum purpureum. Leguminous shrub species included Cajanus cajan, Cratylia argentea, Gliricidia sepium, Leucaena leucocephala and Stylosanthes guianensis and non-leguminous shrub species included Annona senegalensis, Moringa oleifera, Securinega virosa and Vitellaria paradoxa. Leaves were harvested, dried at 55°C and ground through a 1 mm screen. Serum bottles containing 500 mg of forage, modified McDougall’s buffer and rumen fluid were incubated under anaerobic conditions at 39°C for 24 h. Samples of each forage type were removed after 0, 2, 6, 12 and 24 h of incubation for determination of cumulative gas production. Methane production, ammonia concentration and proportions of VFA were measured at 24 h. Concentration of aNDF (g/kg DM) ranged from 671 to 713 (grasses), 377 to 590 (leguminous shrubs) and 288 to 517 (non-leguminous shrubs). After 24 h of in vitro incubation, cumulative gas, CH4 production, ammonia concentration, proportion of propionate in VFA and IVDMD differed (p<0.05) within each forage type. B. ruziziensis and G. sepium produced the highest cumulative gas, IVDMD, total VFA, proportion of propionate in VFA and the lowest A:P ratios within their forage types. Consequently, these two species produced moderate CH4 emissions without compromising digestion. Grazing of these two species may be a strategy to reduce CH4 emissions however further assessment in in vivo trials and at different stages of maturity is recommended.

Board-invited review: Opportunities and challenges in using exogenous enzymes to improve ruminant production.

The ability of ruminants to convert plant biomass unsuitable for human consumption into meat and milk is of great societal and agricultural importance. However, the efficiency of this process is largely dependent on the digestibility of plant cell walls. Supplementing ruminant diets with exogenous enzymes has the potential to improve plant cell wall digestibility and thus the efficiency of feed utilization. Understanding the complexity of the rumen microbial ecosystem and the nature of its interactions with plant cell walls is the key to using exogenous enzymes to improve feed utilization in ruminants. The variability currently observed in production responses can be attributed to the array of enzyme formulations available, their variable activities, the level of supplementation, mode of delivery, and the diet to which they are applied as well as the productivity level of the host. Although progress on enzyme technologies for ruminants has been made, considerable research is still required if successful formulations are to be developed. Advances in DNA and RNA sequencing and bioinformatic analysis have provided novel insight into the structure and function of rumen microbial populations. Knowledge of the rumen microbial ecosystem and its associated carbohydrases could enhance the likelihood of achieving positive responses to enzyme supplementation. The ability to sequence microbial genomes represents a valuable source of information in terms of the physiology and function of both culturable and unculturable rumen microbial species. The advent of metagenomic, metatranscriptomic, and proteomic techniques will further enhance our understanding of the enzymatic machinery involved in cell wall degradation and provide a holistic view of the microbial community and the complexities of plant cell wall digestion. These technologies should provide new insight into the identification of exogenous enzymes that act synergistically with the rumen microbial populations that ultimately dictate the efficiency of feed digestion.

Effects of nonstructural carbohydrate concentration in alfalfa on fermentation and microbial protein synthesis in continuous culture

Insufficient readily fermentable energy combined with extensive degradation of proteins in alfalfa (Medicago sativa L.) may result in poor forage N utilization by ruminants. Using the inherent genetic variability and differences between harvests, our objective was to compare the effect of contrasting concentrations of nonstructural carbohydrates (NSC) in alfalfa on rumen fermentation and microbial protein synthesis. Individual genotypes of the alfalfa cultivar AC Caribou grown near Québec City, Québec, Canada, were harvested at the vegetative and early flowering stages, dried at 55 degrees C, ground, and analyzed for soluble carbohydrates (fructose + sucrose + glucose + pinitol) and starch. Approximately 20 genotypes having, respectively, the highest and lowest NSC concentrations were pooled to constitute 2 contrasted 1-kg forage samples. Samples of high- (17.9% DM) and low- (7.4% DM) NSC alfalfa were respectively allocated to separate dual-flow fermenters in a completely randomized design with 3 replications. Rumen inoculum was obtained from 4 ruminally fistulated cows in early lactation that were fed a TMR with a 50:50 forage to concentrate ratio. A 10-d incubation period was used, with the first 6 d serving as an adaptation period followed by 4 d of sampling with solid and liquid dilution rates in the fermenters set at approximately 2.0 and 4.3%/h, respectively. High versus low NSC concentration in alfalfa significantly enhanced the apparent digestibility of OM (59.1% for high-NSC alfalfa vs. 54.4% for low-NSC alfalfa) and DM (60.0 vs. 54.3%) and the true digestibility of DM (74.1 vs. 64.7%). Increasing NSC concentration in alfalfa (high vs. low) significantly decreased ruminal pH (6.85 vs. 7.08) and NH(3)-N concentration (26.0 vs. 33.6 mg/dL) and increased total VFA concentration (94.9 vs. 83.0mM). Molar proportions of acetate, isobutyrate, and isovalerate significantly decreased, whereas molar proportions of propionate and butyrate significantly increased with high-NSC alfalfa, resulting in a more glucogenic fermentation. More importantly, microbial N flow (263 vs. 230 mg/d) and bacterial N efficiency (41.1 vs. 29.6% of available N), measured using (15)N as a microbial marker, both significantly increased with the high-NSC alfalfa. These results indicate that increasing the concentration of NSC in alfalfa promotes a glucogenic fermentation and enhances microbial N synthesis in the rumen.

Effects of corn-, wheat- or triticale dry distillers' grains with solubles on in vitro fermentation, growth performance and carcass traits of lambs.

The objective of this study was to determine the effect of replacing a mixture of canola meal and barley grain with corn-, wheat- or triticale dry distillers’ grains with solubles (DDGS) at 20% of dietary dry matter (DM) on in vitro ruminal fermentation in bovine ruminal fluid and on growth performance and carcass characteristics of lambs. Sixty ram lambs (22.6 ± 3.0 kg) were randomly assigned to one of four dietary treatments and given individual ad libitum access to feed until they attained slaughter weight. The control diet consisted (DM basis) of 54% barley grain, 16% sunflower hulls, 11.5% beet pulp, 10% canola meal, 2.5% canola oil and 6.0% molasses, vitamins and minerals mixture. For the three DDGS dietary treatments, 10% barley grain and 10% canola meal were replaced with 20% corn-, wheat-or triticale-DDGS. The source of DDGS did not influence (P > 0.51) dry matter intake (DMI) or average daily gain (ADG). Feed conversion (feed:gain) of lambs fed wheat DDGS was approx. 12% poorer (P < 0.05) than t...

Avian (IgY) anti-methanogen antibodies for reducing ruminal methane production: in vitro assessment of their effects

In vitro dry matter disappearance (IVDMD) and production of methane, volatile fatty acids (VFA) and ammonia from an early lactation diet or from freeze-dried alfalfa were assessed in the presence of anti-methanogen antibody treatments in two in vitro ruminal incubations (experiments 1 and 2). In experiment 1, hens were immunised with crude cell preparations of Methanobrevibacter smithii, Methanobrevibacter ruminantium or Methanosphaera stadtmanae and complete Freund’s adjuvant (CFA). Semipurified egg antibodies (IgY) prepared from the hens’ eggs (α-SMICFA, α-RUMCFA, or α-STADCFA, respectively) were dispensed into 24 replicate vials (400 μL per vial) containing 500 mg of an early lactation total mixed ration (18% crude protein; 33% neutral detergent fibre; DM basis). Vials containing an equal volume of semipurified antibodies from eggs of non-immunised hens were included as a control. In experiment 2, hens were immunised with one of the three antigenic preparations combined with Montanide ISA 70 adjuvant. Triplicate vials per time point included 0.6 g of freeze-dried egg powder (α-SMIMon, α-RUMMon, α-STADMon; 19.0 ± 2.6 mg IgY/g) or a mixture of all three (ComboMon) and 500 mg of freeze-dried alfalfa. Total gas, methane production and pH were measured at intervals over 24 h. After 24 h, samples were analysed for VFA, ammonia and IVDMD. In experiment 1, cumulative CH4 production was similar (P > 0.05) among treatments at each sampling time. At 24 h, average CH4 production across treatments was 27.03 ± 0.205 mg/g DM. In experiment 2, α-SMIMon, α-STADMon and ComboMon reduced methane production at 12 h (P ≤ 0.05) compared with the control, but by 24 h, CH4 levels in all treatments were similar (P > 0.05) to the control. At 24 h, total VFA concentrations were lower (P < 0.05) in α-RUMMon and α-SMIMon than in the control. The transient nature of the inhibition of methane production by the antibodies may have arisen from instability of the antibodies in ruminal fluid, or to the presence of non-culturable methanogens unaffected by the antibody activity that was administered.