A.T. Adesogan

SPECIAL TOPICS — Mitigation of methane and nitrous oxide emissions from animal operations: I. A review of enteric methane mitigation options

The goal of this review was to analyze published data related to mitigation of enteric methane (CH4) emissions from ruminant animals to document the most effective and sustainable strategies. Increasing forage digestibility and digestible forage intake was one of the major recommended CH4 mitigation practices. Although responses vary, CH4 emissions can be reduced when corn silage replaces grass silage in the diet. Feeding legume silages could also lower CH4 emissions compared to grass silage due to their lower fiber concentration. Dietary lipids can be effective in reducing CH4 emissions, but their applicability will depend on effects on feed intake, fiber digestibility, production, and milk composition. Inclusion of concentrate feeds in the diet of ruminants will likely decrease CH4 emission intensity (Ei; CH4 per unit animal product), particularly when inclusion is above 40% of dietary dry matter and rumen function is not impaired. Supplementation of diets containing medium to poor quality forages with small amounts of concentrate feed will typically decrease CH4 Ei. Nitrates show promise as CH4 mitigation agents, but more studies are needed to fully understand their impact on whole-farm greenhouse gas emissions, animal productivity, and animal health. Through their effect on feed efficiency and rumen stoichiometry, ionophores are likely to have a moderate CH4 mitigating effect in ruminants fed high-grain or mixed grain-forage diets. Tannins may also reduce CH4 emissions although in some situations intake and milk production may be compromised. Some direct-fed microbials, such as yeast-based products, might have a moderate CH4-mitigating effect through increasing animal productivity and feed efficiency, but the effect is likely to be inconsistent. Vaccines against rumen archaea may offer mitigation opportunities in the future although the extent of CH4 reduction is likely to be small and adaptation by ruminal microbes and persistence of the effect is unknown. Overall, improving forage quality and the overall efficiency of dietary nutrient use is an effective way of decreasing CH4 Ei. Several feed supplements have a potential to reduce CH4 emission from ruminants although their long-term effect has not been well established and some are toxic or may not be economically feasible.

Special topics--Mitigation of methane and nitrous oxide emissions from animal operations: III. A review of animal management mitigation options.

The goal of this review was to analyze published data on animal management practices that mitigate enteric methane (CH4) and nitrous oxide (N2O) emissions from animal operations. Increasing animal productivity can be a very effective strategy for reducing greenhouse gas (GHG) emissions per unit of livestock product. Improving the genetic potential of animals through planned cross-breeding or selection within breeds and achieving this genetic potential through proper nutrition and improvements in reproductive efficiency, animal health, and reproductive lifespan are effective approaches for improving animal productivity and reducing GHG emission intensity. In subsistence production systems, reduction of herd size would increase feed availability and productivity of individual animals and the total herd, thus lowering CH4 emission intensity. In these systems, improving the nutritive value of low-quality feeds for ruminant diets can have a considerable benefit on herd productivity while keeping the herd CH4 output constant or even decreasing it. Residual feed intake may be a tool for screening animals that are low CH4 emitters, but there is currently insufficient evidence that low residual feed intake animals have a lower CH4 yield per unit of feed intake or animal product. Reducing age at slaughter of finished cattle and the number of days that animals are on feed in the feedlot can significantly reduce GHG emissions in beef and other meat animal production systems. Improved animal health and reduced mortality and morbidity are expected to increase herd productivity and reduce GHG emission intensity in all livestock production systems. Pursuing a suite of intensive and extensive reproductive management technologies provides a significant opportunity to reduce GHG emissions. Recommended approaches will differ by region and species but should target increasing conception rates in dairy, beef, and buffalo, increasing fecundity in swine and small ruminants, and reducing embryo wastage in all species. Interactions among individual components of livestock production systems are complex but must be considered when recommending GHG mitigation practices.

Mitigation of methane and nitrous oxide emissions from animal operations: III. A review of animal management mitigation options

This review analyzes published data on manure management practices used to mitigate methane (CH4) and nitrous oxide (N2O) emissions from animal operations. Reducing excreted nitrogen (N) and degradable organic carbon (C) by diet manipulation to improve the balance of nutrient inputs with production is an effective practice to reduce CH4 and N2O emissions. Most CH4 is produced during manure storage; therefore, reducing storage time, lowering manure temperature by storing it outside during colder seasons, and capturing and combusting the CH4 produced during storage are effective practices to reduce CH4 emission. Anaerobic digestion with combustion of the gas produced is effective in reducing CH4 emission and organic C content of manure; this increases readily available C and N for microbial processes creating little CH4 and increased N2O emissions following land application. Nitrous oxide emission occurs following land application as a byproduct of nitrification and dentrification processes in the soil, but these processes may also occur in compost, biofilter materials, and permeable storage covers. These microbial processes depend on temperature, moisture content, availability of easily degradable organic C, and oxidation status of the environment, which make N2O emissions and mitigation results highly variable. Managing the fate of ammoniacal N is essential to the success of N2O and CH4 mitigation because ammonia is an important component in the cycling of N through manure, soil, crops, and animal feeds. Manure application techniques such as subsurface injection reduce ammonia and CH4 emissions but can result in increased N2O emissions. Injection works well when combined with anaerobic digestion and solids separation by improving infiltration. Additives such as urease and nitrification inhibitors that inhibit microbial processes have mixed results but are generally effective in controlling N2O emission from intensive grazing systems. Matching plant nutrient requirements with manure fertilization, managing grazing intensity, and using cover crops are effective practices to increase plant N uptake and reduce N2O emissions. Due to system interactions, mitigation practices that reduce emissions in one stage of the manure management process may increase emissions elsewhere, so mitigation practices must be evaluated at the whole farm level.

Effect of applying inoculants with heterolactic or homolactic and heterolactic bacteria on the fermentation and quality of corn silage

This study examined the effect of applying different bacterial inoculants on the fermentation and quality of corn silage. Corn plants were harvested at 35% DM, chopped, and ensiled in 20-L mini silos after application of (1) deionized water (CON) or inoculants containing (2) 1 × 10(5) cfu/g of Pediococcus pentosaceus 12455 and Propionibacteria freudenreichii (B2); (3) 4 × 10(5) cfu/g of Lactobacillus buchneri 40788 (BUC); or (4) 1 × 10(5) cfu/g of Pediococcus pentosaceus 12455 and 4 × 10(5) cfu/g of L. buchneri 40788 (B500). Four replicates of each treatment were weighed into polyethylene bags within 20-L mini silos. Silos were stored for 575 d at ambient temperature (25°C) in a covered barn. After silos were opened, aerobic stability, chemical composition, and yeast and mold counts were determined. The DNA in treated and untreated silages was extracted using lysozyme/sodium dodecyl sulfate lysis and phenol/chloroform and used as a template for a conventional PCR with primers designed on the 16S rRNA gene to detect the presence of L. buchneri in all silage samples. Acetic acid concentration was greater in B2 silages versus others (6.46 vs. 4.23% DM). Silages treated with BUC and B500 had lower pH and propionic acid concentration and greater lactic acid concentration than others. The B500 silage had the greatest lactic:acetic acid ratio (1.54 vs. 0.41), and only treatment with BUC reduced DM losses (5.0 vs. 14.3%). Yeast and mold counts were less than the threshold (10(5)) typically associated with silage spoilage and did not differ among treatments. Consequently, all silages were very stable (>250 h). Aerobic stability was not improved by any inoculant but was lower in B500 silages versus others (276 vs. 386 h). The conventional PCR confirmed the presence of similar populations of L. buchneri in all silages. This may have contributed to the prolonged aerobic stability of all silages.

A comparison of filter bag methods with conventional tube methods of determining the in vitro digestibility of forages.

In vitro digestibility of forages is commonly estimated by two-stage methods in which the various samples are kept completely separate from one another, using tubes. A possible alternative approach, which may save labour, is to use larger vessels, within which up to as many as 25 samples are incubated, each contained in its own filter bag. The two approaches were compared for estimating apparent dry matter (DM) digestibility, apparent digestible organic matter in DM, true DM digestibility, true digestible organic matter in DM and digestibility of neutral detergent fibre. The forage samples analysed comprised all 72 combinations of two forage species (Lolium multiflorum and Medicago sativa), three plant parts (whole crop, leaf and stem), three degrees of particle breakdown (0.5, 1.0 and 1.5 mm sieve size when milling) and four field replicates. Rumen fluid from sheep was used for two field replicates and rumen fluid from cattle for the other two. There was no discernible effect on digestibility of the sieve size used when milling, e.g. true digestible organic matter in dry matter using filter bags was 674, 677 and 663 g kg ˇ1 , respectively, (SE 6.4) with the 0.5, 1.0 and 1.5 mm sieves. There were smaller differences between the two forage species (in respect of whole crop, stem and leaf) with the filter bag than with the tube method. The standard errors and coefficients of variation were higher with the filter bag than with the tube method; of 16 coefficients of variation calculated for each method, the mean with filter bags was 4.0% and the mean with tubes was 2.7%. Linear regression indicated that true digestibility using tubes could be predicted more precisely than apparent digestibility using tubes from the results using filter bags. The difference between apparent and true digestibility, when estimated using filter bags, appeared unrealistically low. The estimates of forage digestibility when using rumen fluid from sheep were very similar to those when using rumen fluid from cattle. It is concluded that the traditional methods, using tubes, are likely to give more precise results than

Effect of fibrolytic enzyme application to low- and high-concentrate diets on the performance of lactating dairy cattle

The objective of this study was to examine the effect of applying a fibrolytic enzyme preparation to diets with high (48% of diet dry matter, DM) or low (33% of diet DM) proportions of concentrate on production performance of lactating dairy cows. Sixty lactating Holstein cows (589 kg ± 20; 22 ± 3 d in milk) were stratified according to milk production and parity and randomly assigned to 4 treatments with a 2 × 2 factorial arrangement. Dietary treatments included the following: 1) low-concentrate diet (LC); 2) LC plus enzyme (LCE); 3) high-concentrate diet (HC); and 4) HC plus enzyme (HCE). The enzyme was sprayed at a rate of 3.4 mg of enzyme/g of DM on the total mixed ration daily and the trial lasted for 63 d. A second experiment with a 4 × 4 Latin square design used 4 ruminally fistulated cows to measure treatment effects on ruminal fermentation and in situ ruminal dry matter degradation during four 18-d periods. Enzyme application did not affect dry matter intake (DMI; 23.9 vs. 22.3 kg/d) or milk production (32.8 vs. 34.2 kg/d) but decreased estimated CH(4) production, increased total volatile fatty acid concentration (114.5 vs. 125.7 mM), apparent total tract digestibility of DM (69.8 vs. 72.6%), crude protein (CP; 69.2 vs. 73.3%), acid detergent fiber (50.4 vs. 54.8%), neutral detergent fiber (53.7 vs. 55.4%), and the efficiency of milk production (1.44 vs. 1.60 kg of milk/kg of DMI). Feeding more concentrates increased DMI (21.5 vs. 24.8 kg/d), milk yield (32.2 vs. 34.7 kg/d), milk protein yield (0.89 vs. 0.99 kg/d), and DM (69.9 vs. 72.6%), but decreased ruminal pH (6.31 vs. 6.06). Compared with cows fed HC, those fed LCE had lower DMI (20.8 vs. 25.7 kg/d) and CP intake (3.9 vs. 4.8 kg/d), greater ruminal pH (6.36 vs. 6.10), and similar milk yield (33.2 ± 1.1 kg/d). Consequently, the efficiency of milk production was greater in cows fed LCE than those fed HC (1.69 vs. 1.42 kg of milk/kg of DMI). This fibrolytic enzyme increased the digestibility of DM, CP, neutral detergent fiber, and acid detergent fiber and the efficiency of milk production by dairy cows. Enzyme application to the low-concentrate diet resulted in as much milk production as that from cows fed the untreated high-concentrate diet.

Effect of applying molasses or inoculants containing homofermentative or heterofermentative bacteria at two rates on the fermentation and aerobic stability of corn silage

This study determined how the fermentation and aerobic stability of corn silage are affected by treatment with molasses or 2 dual-purpose inoculants applied at or above the recommended rate. Corn forage (DeKalb 69-70) was harvested at 39% dry matter (DM) and ensiled after treatment with no additives (control, CON), molasses (MOL), Buchneri 500 inoculant, or Pioneer 11C33 inoculant. Molasses was applied at 3% of forage DM. Buchneri 500 was applied at the recommended rate of 8 mg/kg fresh forage to supply 1 x 10(5) cfu/g of Pediococcus pentosaceus 12455 and 4 x 10(5) cfu/g of Lactobacillus buchneri 40788 (BB) or at twice the recommended rate (DBB). Pioneer 11C33 inoculant was applied at the recommended rate of 1.1 mg/kg fresh forage to supply 1 x 10(5) cfu/g of a mixture of Lactobacillus plantarum, L. buchneri, and Enteroccocus faecium (PN) or at twice the recommended rate (DPN). Each treatment was applied in quadruplicate and the treated forages were ensiled within 20-L mini silos for 135 d at 18 to 35 degrees C. Molasses-treated silages had greater ash and starch concentrations than CON silages and greater lactate and ethanol concentrations than other silages. Like CON silages, MOL silages had high yeast counts (>10(5) cfu/g); consequently, they deteriorated within 30 h as shown by temperature increase. Inoculant-treated silages had lower lactate to acetate ratios than CON or MOL silages largely because they had greater acetate concentrations. Consequently, all inoculant-treated silages had fewer yeasts (<10(5) cfu/g) and were more stable (>30 h) than CON and MOL silages. When applied at recommended rates, PN and BB had similar effects on silage chemical composition, fermentation, fungal counts, and aerobic stability, except for a lower lactate concentration in PN silages. Concentrations of VFA, and NH(3)-N, pH, and extent of aerobic stability were similar for PN, DPN, BB, and DBB silages. However, lactate concentration was greater in DPN than in PN. In conclusion, MOL application increased ethanol and lactate concentration and did not improve aerobic stability. Both dual-purpose inoculants made the fermentation more heterolactic and thereby improved the aerobic stability of corn silage. Doubling the rate of application of either inoculant did not further improve fermentation or aerobic stability.

The effect on voluntary feed intake, in vivo digestibility and nitrogen balance in sheep of feeding grass silage or pea–wheat intercrops differing in pea to wheat ratio and maturity

Adesogan, A.T., Salawu, M.B., Deaville, E.R. (2002). The effect on voluntary feed intake, in vivo digestibility and nitrogen balance in sheep of feeding grass silage or pea?wheat intercrops differing in pea to wheat ratio and maturity. Animal Feed Science and Technology, 96, (3-4), 161-173. Sponsorship: Milk Development Council

Dry matter yield and nutritive value of pea/wheat bi-crops differing in maturity at harvest, pea to wheat ratio and pea variety

Studies were conducted over 3 years to evaluate the effect of maturity at harvest (Year 1 and 2), pea content (Year 2) and pea variety (Magnus versus Setchey, Year 3) on the nutritional quality of inter-cropped, spring-sown, pea/wheat bi-crop forages. Herbage samples were taken at different stages of growth for separation of component crops (peas and wheat) and estimation of dry matter (DM) content, DM yield, chemical composition and in vitro digestible organic matter in DM (DOMD). The DM yields generally increased with maturity and the average bi-crop DM yields was highest in Year 3. Peas had higher crude protein (CP) and DOMD but lower neutral detergent fibre (NDF) and acid detergent fibre (ADF) than wheat. For both peas and wheat, the DM, CP, starch, NDF and DOMD at harvest were higher in the second cut (15 weeks after planting) than in the first cut (13 weeks after planting). The DM yield, CP, starch, WSC, NDF, ADF content of the bi-crops and their DOMD yields were all influenced by the stage of maturity and the proportion of peas to wheat in the bi-crops. The results show that inter-cropped spring sown pea/wheat bi-crops can be harvested between 13 and 16 weeks after planting. However, relative to other stages of maturity measured, harvesting when the wheat was at early to soft dough stage and the peas at yellow wrinkle pod stage appeared optimal. In comparison with the pea variety Magnus, the lower NDF and ADF, and higher CP, WSC, starch and DOMD in the pea variety Setchey suggests that the latter is nutritionally better. In deciding when to harvest, the chemical composition and stages of growth of both peas and wheat are important. However, because there is little decline in the quality of peas with maturity, it may be possible, in certain conditions (e.g. absence of lodging, infections or senescence in peas), to use the stage of maturity of wheat only as the index of the ideal time to harvest pea/wheat bi-crop for conservation as forage for ruminants.

Intake, digestibility, and nitrogen retention by sheep supplemented with warm-season legume haylages or soybean meal

The high cost of commercial supplements necessitates evaluation of alternatives for ruminant livestock fed poor quality warm-season grasses. This study determined how supplementing bahiagrass haylage (Paspalum notatum Flügge cv. Tifton 9) with soybean [Glycine max (L.) Merr.] meal or warm-season legume haylages affected the performance of lambs. Forty-two Dorper x Katadhin lambs (27.5 +/- 5 kg) were fed for ad libitum intake of bahiagrass haylage (67.8% NDF, 9.6% CP) alone (control) or supplemented with soybean meal (18.8% NDF, 51.4% CP) or haylages of annual peanut [Arachis hypogaea (L.) cv. Florida MDR98; 39.6% NDF, 18.7% CP], cowpea [Vigna unguiculata (L.) Walp. cv. Iron clay; 44.1% NDF, 16.0% CP], perennial peanut (Arachis glabrata Benth. cv. Florigraze; 40.0% NDF, 15.8% CP), or pigeonpea [Cajanus cajan (L.) Millsp. cv. GA-2; 65.0% NDF, 13.7% CP]. Haylages were harvested at the optimal maturity for maximizing yield and nutritive value, wilted to 45% DM, baled, wrapped in polyethylene plastic, and ensiled for 180 d. Legumes were fed at 50% of the dietary DM, and soybean meal was fed at 8% of the dietary DM to match the average CP concentration (12.8%) of legume haylage-supplemented diets. Lambs were fed each diet for a 14-d adaptation period and a 7-d data collection period. Each diet was fed to 7 lambs in period 1 and 4 lambs in period 2. Pigeonpea haylage supplementation decreased (P < 0.01) DM and OM intake and digestibility vs. controls. Other legume haylages increased (P < 0.05) DM and OM intake vs. controls; however, only soybean meal supplementation increased (P = 0.01) DM digestibility. All supplements decreased (P = 0.05) NDF digestibility. Except for pigeonpea haylage, all supplements increased (P < 0.01) N intake, digestibility, and retention, and the responses were greatest (P = 0.04) with soybean meal supplementation. Microbial N synthesis was reduced (P = 0.02) by pigeonpea haylage supplementation, but unaffected (P = 0.05) by other supplements. Efficiency of microbial protein synthesis was unaffected (P = 0.05) by diet. Ruminal ammonia concentration was increased (P = 0.01) by all supplements, but only soybean meal and annual peanut haylage increased (P < 0.03) plasma urea-N concentrations. Perennial peanut, annual peanut, and cowpea haylages are promising protein supplements for growing lambs.