Project Number: 8070-21000-009-04-A
Project Type: Cooperative Agreement
Start Date: Oct 1, 2016
End Date: Aug 31, 2019
We hypothesize that brassicas will produce superior animal performance while emitting less methane per cow compared with annual ryegrass. Foliar glucosinolate concentration will be positively correlated with methane output reduction. To test this overreaching hypothesis, we will establish field plots (ARS) and a grazing experiment (UNH) to determine the animal performance and methane mitigation potential of three forage brassica species. These experiments will provide the project team with science-based recommendations for use of individual brassica species on northeastern dairy farms.
In July 2017, six pastures at the UNH Organic Dairy Research Farm in Durham, NH, will be randomly established to either annual ryegrass or a forage brassica (variety chosen based on data from Year 1). Planting date is one month earlier due to climatic differences between locations. In August 2017; 24 multiparious, Jersey cows will be blocked based on milk production and randomly assigned to one of two groups (12 animals/group). Body condition score, weight and milk production and composition will be determined prior to experiment. Grazing will initiate 45 days after planting and animals will have access to treatment pastures after the morning milking for 8 hours and will be removed from pasture 4 hours before the evening milking (typical producer practice to “flush” brassicas from system and prevent off-flavor in milk). Animals will be kept in the barn prior to the evening milk and will be given a baleage and concentrate diet at this time. Animals will be turned out as a group on a grass pasture during the night hours. Dry matter intake of conserved feeds, brassica pasture, and grass pasture will be determined by utilizing a grow-safe system for feeding, an internal marker to determine pasture intake and by determining forage availability pre- and post-grazing. Each group will be rotated through each replicate pasture every 3 days. Animals will have ad libitum access to water at all times.