Beef Average Daily Gain and Enteric Methane Emissions on Birdsfoot Trefoil, Cicer Milkvetch and Meadow Brome Pastures

Conventional production of meat products from ruminant animals in the United States requires inputs including the cultivation and nitrogen fertilization of annual grains such as corn and barley, and transportation of cattle and grain to feedlots. Consumers have concerns about the impact of feedlot conditions on animal health, and about the implications of pharmaceutical inputs such as growth hormones and antibiotics on the environment and human health. These concerns have led to a growing interest in pasturefinished meat production by consumers. Such smaller-scale livestock production systems can be healthier and lower-stress for animals, are integrated into local food systems and are more transparent to consumers, and have higher potential profitability for producers than traditional ruminant production methods. There is a strong market for pasture-finished beef products, and prices for naturally or organically raised beef have remained well above feedlot-produced product prices. There is also concern about the impact of ruminant production on the environment, including air and water pollution from feedlot production and greenhouse gasses that are emitted from ruminant animals during feed digestion. This thesis project explored the potential of a beef production system based on perennial legumes, including the non-bloating legume birdsfoot trefoil (BFT; Lotus corniculatus L.) for producing meat products from cattle while reducing concentrate feeding and methane production. The condensed tannins that are produced by BFT bind proteins in the rumen but allow them to be digested in the abomasum and intestines, which in turn leads to better utilization of forage nutrients during the finishing period and higher gains or milk production. The higher digestibility of legumes compared with grasses reduces methane emissions in cattle both through higher digestibility of the forage and through direct impacts on methanogens operating in the rumen. As reported in this thesis, steers finished on BFT gained significantly more weight per day than steers fed another perennial forage legume, cicer milkvetch, but did not gain as rapidly as feedlot-fed steers. At the end of summer grazing, the blood plasma of pasture-fed steers was lower in saturated and omega-6 fatty acids and higher in transvaccenic and omega-3 fatty acids than the blood plasma of feedlot-fed steers. When beef cows grazed grass and legume pastures, enteric methane emissions were lower on the legume pastures than the grass pasture. These results demonstrate that, compared with other feed sources, perennial legume pastures used for cattle production can improve cattle gains and reduce environmental impacts

Increased Nitrogen Retention and Reduced Methane Emissions of Beef Cattle Grazing Legume vs. Grass Irrigated Pastures in the Mountain West USA

Grazing studies were carried out over a 5-year period using pregnant cows, yearling calves and 2-year-old heifers to investigate the influence of diet on intake, methane (CH4) emissions and retention of nitrogen (N). Monoculture legume (birdsfoot trefoil, BFT and cicer milkvetch, CMV) or grass (meadow bromegrass, MBG) pastures were rotationally stocked, and during year 4 and year 5, treatments were contrasted with total mixed rations (TMR) fed in confinement. The sulfur hexafluoride (SF6) method was used to continuously measure enteric CH4 emissions. Intake was greater on legume pastures and on TMR than on grass pastures, and enteric CH4 emissions per unit of intake were lower on legumes compared with grass pastures. Legume pastures had elevated non-fiber carbohydrate (NFC) concentrations (400 g kg−1 dry matter; DM) typical of perennial legumes cultivated in the Mountain West. A N balance calculated in 2017–2018 demonstrated that N retention was greater for TMR and legume than grass pastures. Enteric CH4 emissions of grazing cow herds account for the majority of greenhouse gas (GHG) emissions from beef production and can be significantly reduced by using highly digestible forage legumes. The N retention of legumes can potentially enhance the efficiency of N use, thereby increasing the sustainability of grasslands.EEA BordenaveFil: MacAdam, Jennifer W. Utah State University. College of Agriculture and Applied Sciences. Department of Plants, Soils and Climate; Estados Unidos.Fil: Pitcher, Lance R. Amalgamated Sugar Company; Estados UnidosFil: Bolletta, Andrea Ivana. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bordenave; Argentina.Fil: Guevara Ballesteros, Raúl David. Universidad Autónoma de Barcelona. Animal Welfare Education Centre; EspañaFil: Beauchemin, Karen A. Agriculture and Agri-Food Canada. Lethbridge Research and Development Centre; CanadáFil: Xin, Dai. Utah State University. Utah Agricultural Experiment Station; Estados Unidos.Fil: Villalba, Juan J. Utah State University. Quinney College of Natural Resources. Department of Wildland Resources; Estados Unidos

Beef average daily gain and enteric methane emissions on birdsfoot trefoil, cicer milkvetch and meadow brome pastures

This thesis project explored the use of perennial legumes, including the non-bloating birdsfoot trefoil (BFT; Lotus corniculatus L.) for beef production. In 2011 and 2012, cattle averaged approximately 300 kg at the beginning of the grazing season, and approximately 450 kg in 2013. Average daily gain on pastures ranged from a low of 0.63 kg d-1 on cicer milkvetch (CMV; Astragalus cicer L.) in 2011 and 2013 to a high of 1.03 kg d-1 on Norcen BFT in 2013. Feedlot gains ranged from 1.14 to 1.57 kg d-1. Blood plasma fatty acids did not differ when feeding treatments were imposed, but at the end of each grazing season saturated and omega-6 fatty acids were elevated in feedlot-fed cattle compared with pasture-fed cattle, while trans-vaccenic acid (TVA) and omega-3 fatty acids were elevated in pasture-fed cattle. The ratio of omega-6 to omega-3 fatty acids was always higher in feedlot-fed cattle at the end of the grazing season, but in 2013, when all cattle were nearing slaughter weight, the omega-6 to omega-3 ratio was 50% higher for feedlot-fed than for BFT-fed cattle and double that of grass-fed cattle. Digestive (enteric) methane (CH4) production of beef cows was lower when cattle grazed BFT and CMV pastures (167 and 159 g CH4 per cow per d, respectively) compared to cows on meadow bromegrass (MB; Bromus riparus Rehmann) (355 g CH4 per cow per d). Meadow bromegrass has more fiber than legume forages, which will increase the proportion of acetate to propionate created by microbial digestion in the rumen, increasing the production and release of CH4. Perennial legume forages fix nitrogen, eliminating the need for chemical nitrogen fertilizer, and tannin-containing legumes can be grazed without risk of bloat. These forages will play an important role in developing more environmentally and economically sustainable agricultural production systems

Beef Steer Performance on Irrigated Monoculture Legume Pastures Compared with Grass- and Concentrate-Fed Steers

Fall- or spring-born steers grazed monoculture irrigated birdsfoot trefoil (BFT; Lotus corniculatus L.) or cicer milkvetch (CMV; Astragalus cicer L.) pastures for approximately 12 weeks for 3 years and were compared with steers on concentrate diets. In the 3rd year, an irrigated meadow bromegrass (MBG; Bromus biebersteinii Roem. and Schult.) pasture treatment was added for further comparison. Steer average daily gain (ADG) was 1.31, 0.94, 0.83 and 0.69 kg d−1 on concentrate, ‘Norcen’ BFT, ‘Oberhaunstadter’ BFT, and ‘Monarch’ CMV diets, respectively; ADG on grass pastures was 0.43 kg d−1. The ADG on the concentrate diet was greater than ADG on legume or grass pastures, ADG was greater on BFT than CMV in every year (p p < 0.03). The rate constant of gas production of an in vitro rumen fermentation demonstrated a slower rate of microbial digestion for CMV than for BFT. The elevated ADG on BFT pastures may be due to greater non-fiber carbohydrate (NFC) concentration and reduced neutral detergent fiber (NDF) concentration combined with condensed tannins that protect proteins in the rumen but do not impede protein digestion in the abomasum and intestines