Glycine biosynthesis in rat and sheep muscle

Glycine is the third most abundant of the amino acids released by muscle. Perfused rat hind-limb and sheep diaphragm preparations were employed to study the origin of glycine produced by non-ruminant and ruminant muscle. Neither the degradation of muscle and erythrocyte glutathione nor the 'leaching out' of the intracellular glycine pool contributed to the glycine released by either muscle. When the perfusions were carried out with the medium free of amino acids, the proteolysis accounted for 57% of the total glycine release by the rat hind-limb and 38% by the sheep diaphragm. Minimum de novo synthesis of glycine was 12.3 umol/3 h/30 g in the rat muscle and 10.3 umol/3 h/30 g in the sheep muscle. Addition of serine to the perfusion medium stimulated significantly both the rate of glycine efflux and total glycine production in the rat hind-limb. Similar results were obtained with the sheep diaphragm; however, the increases were not statistically significant. Addition of 5-formyl tetrahydrofolate, a specific inhibitor of serine hydroxymethyltransferase, SHMT (EC 2.1.2.1) significantly decreased the rate of glycine efflux from both the muscles. The observations using cold serine were confirmed with the experiments employing radioisotopes. Up to 40% of total glycine produced by the rat hind-limb was derived from serine, whereas in the sheep diaphragm it was only 4%. In both the muscles synthesis of glycine from serine was by SHMT and not glycine synthase (EC 2.1.2.10). Synthesis of glycine from threonine was negligible in both the muscles. SHMT activity increased in liver, diaphragm and hind-limb muscle of female rats treated with trenbolone acetate or testosterone, anabolic agents. Both the muscles incorporated 14C from (U-14C) serine and (3-14C) serine to methionine, cystine, alanine, aspartate and glutamate + glutamine. The label from (U-14C) glucose was recovered in serine and glycine in the rat hind-limb but not in the sheep diaphragm. A 'serine-glycine' cycle involving kidney and muscle is proposed. The possible significance of glycine released by muscle is discussed. Development of a system for the perfusion of sheep diaphragm with erythrocyte-free medium, and a method for the determination of radioactivity in C-2 of glycine also form a part of the thesis

Addition of Purified Tannin Sources and Polyethylene Glycol Treatment on Methane Emission and Rumen Fermentation in Vitro

The objectives of this experiment were (1) to observe the effects of purified tannins and polyethy-lene glycol (PEG) on in vitro rumen fermentation and methanogenesis, and (2) to assess the accuracy of volatile fatty acid (VFA) profiles in predicting methane emission. Hydrolysable and condensed tannins were extracted and purified from chestnut, sumach, mimosa and quebracho. Hay and concentrate mixture (70:30 w/w, 380 mg) was incubated in Hohenheim glass syringe containing 10 mL rumen liquor + 20 mL buffer. The purified tannins were injected into the syringes at a concentration of 1.0 mg/mL each, either without or with PEG 6,000 addition in three replicates. Results revealed that a decrease of methane emission (20%-27%) was observed when the purified tannins were added into basal diet as compared to control (P<0.05), and PEG addition increased methane emission (P<0.05). All purified tannins decreased total gas and total VFA production (P<0.05). The H2 recovery of the treatments ranged from 86.7% to 95.3%. Estimation of methane emission by using VFA profiles revealed an accurate result with a very low root mean square prediction error (1.75%). It is concluded that tannins mitigate methane emission while PEG neutralize such effect, and VFA profiles are accurate predictors of the emission.Key words: tannin, polyethylene glycol, methane, rumen, stoichiometr

Glycine biosynthesis in rat and sheep muscle

Glycine is the third most abundant of the amino acids released by muscle. Perfused rat hind-limb and sheep diaphragm preparations were employed to study the origin of glycine produced by non-ruminant and ruminant muscle. Neither the degradation of muscle and erythrocyte glutathione nor the 'leaching out' of the intracellular glycine pool contributed to the glycine released by either muscle. When the perfusions were carried out with the medium free of amino acids, the proteolysis accounted for 57% of the total glycine release by the rat hind-limb and 38% by the sheep diaphragm. Minimum de novo synthesis of glycine was 12.3 umol/3 h/30 g in the rat muscle and 10.3 umol/3 h/30 g in the sheep muscle. Addition of serine to the perfusion medium stimulated significantly both the rate of glycine efflux and total glycine production in the rat hind-limb. Similar results were obtained with the sheep diaphragm; however, the increases were not statistically significant. Addition of 5-formyl tetrahydrofolate, a specific inhibitor of serine hydroxymethyltransferase, SHMT (EC 2.1.2.1) significantly decreased the rate of glycine efflux from both the muscles. The observations using cold serine were confirmed with the experiments employing radioisotopes. Up to 40% of total glycine produced by the rat hind-limb was derived from serine, whereas in the sheep diaphragm it was only 4%. In both the muscles synthesis of glycine from serine was by SHMT and not glycine synthase (EC 2.1.2.10). Synthesis of glycine from threonine was negligible in both the muscles. SHMT activity increased in liver, diaphragm and hind-limb muscle of female rats treated with trenbolone acetate or testosterone, anabolic agents. Both the muscles incorporated 14C from (U-14C) serine and (3-14C) serine to methionine, cystine, alanine, aspartate and glutamate + glutamine. The label from (U-14C) glucose was recovered in serine and glycine in the rat hind-limb but not in the sheep diaphragm. A 'serine-glycine' cycle involving kidney and muscle is proposed. The possible significance of glycine released by muscle is discussed. Development of a system for the perfusion of sheep diaphragm with erythrocyte-free medium, and a method for the determination of radioactivity in C-2 of glycine also form a part of the thesis

Mitigation of methane and nitrous oxide emissions from animal operations: II. A review of manure 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

Quality assurance for animal feed analysis laboratories

Every sector of the livestock industry, the associated services and the wellbeing of both animals and humans are influenced by animal feeding. The availability of accurate, reliable and reproducible analytical data is imperative for proper feed formulation. Only reliable analysis can lead to the generation of sound scientific data. This document gives a comprehensive account of good laboratory practices, quality assurance procedures and examples of standard operating procedures as used in individual specialist laboratories. The adoption of these practices and procedures will assist laboratories in acquiring the recognition of competence required for certification or accreditation and will also enhance the quality of the data reported by feed analysis laboratories. In addition, ensuring good laboratory practices presented in the document will enhance the safety of the laboratory workers. The document will be useful for laboratory analysts, laboratory managers, research students and teachers and it is hoped that it will enable workers in animal industry, including the aquaculture industry, to appreciate the importance of proven reliable data and the associated quality assurance approaches. An additional effect of implementing and adopting these approaches will be strengthening of the research and education capabilities of students graduating from R&D institutions and promotion of a better trading environment between developing and developed economies. This will have long-term benefits and will promote investment in both feed industries and R&D institutions

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

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