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Milk production, nitrogen utilization, and methane emission of dairy cows grazing grass, forb, and legume-based pastures.

S. Ates




Milk production, nitrogen utilization, and methane emission of dairy cows grazing grass, forb, and legume-based pastures.
R. Wilson1, M. Bionaz1, J. MacAdam2, K. Beauchemin3, H. Naumann4, S. Ates*1. 1Department of Animal and Rangeland Sciences, Oregon State University Corvallis, OR, 2Department of Plants, Soils, and Climate, Utah State University Logan, UT, 3Lethbridge Research and Development Centre, Agriculture and Agri-Food Lethbridge, AB, Canada, 4Division of Plant Sciences, University of Missouri Columbia, MO.

Achieving high animal productivity without degrading the resource base is the primary target in pasture based-dairy farming. This study investigated the effects of changing the forage base in spring from grass-clover pastures to forb or legume-based pastures on milk yield, N partitioning and methane emissions of Jersey cows in Western Oregon. Twenty-seven mid-lactation dairy cows were randomly assigned to 1 of 3 pasture treatments: grass-clover based pasture composed of festulolium, soft-leaf tall fescue, orchardgrass, and white clover (Grass); forb-based pasture composed of chicory, plantain, and white clover (Forb); and legume-based pasture composed of red clover, birdsfoot trefoil, berseem clover and balansa clover (Legume). Pasture were arranged in a randomized complete design with 3 replicates. Production and nutritive quality of the forages, animal performance, nitrogen partitioning, and methane emissions were measured. Data were analyzed by ANOVA with pasture as main effect and plot as random (n = 3). Significance was declared with P ≤ 0.05. Herbage production, feed quality, and DMI of cows were greater in Legume and Forb vs. Grass, with consequent larger milk yield and milk solid concentration. Cows grazing Forb also had higher lactose in milk compared with the other pastures, and lower somatic cell counts compared with Grass. Cow grazing Forb had substantially lower N in urine compared with cows grazing the other pastures but, together with cows grazed on Legume, larger fecal N. Both Forb and Legume had a diuretic effect on cows, as indicated by the lower creatinine concentration in urine but larger proportion of allantoin:creatinine and a tendency (P = 0.08) for greater microbial N production. Methane emissions tended (P = 0.07) to be lower in cows grazed on Forb vs. the other pastures. The results indicated a potential for legume- and forb-based pastures to fulfill nutritional deficiencies in late spring resulting in improved animal performance and health and reduced environmental impact of pasture-based dairy production.

Keywords: pasture systems, nitrogen partitioning, methane emission.

Biography: Dr. Ates holds a PhD in Pasture Sciences from Lincoln University (New Zealand). Before joining OSU, he was a forage scientist at the International Center for Agricultural research in the Dry Areas. Dr. Ates' research focuses on pasture and grazing management for improved animal production and environmental quality. His current research interest includes novel pasture and grazing systems, animal-pasture interactions, evaluation of tannin-containing legumes for livestock grazing, agrivoltaics. In 2015, Dr Ates was elected as a member of the continuing committee for the international grassland congress. He is serving on the editorial board of Grass and Forage Science.