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Whole cottonseed supplementation improves performance and reduces emission intensity of grazing beef cattle

Whole cottonseed supplementation improves performance and reduces emission intensity of grazing beef cattle.

Matthew Beck

Animal Science

The objective of this experiment was to deter mine the effect of whole cottonseed (WCS) supplementation on average daily gain (ADG) and enteric methane (CH4) production of steers grazing native range during spring. Steers (n = 18; body weight = 317 ± 5.5 kg) were adapted to an in-pasture CH4 measurement device (GreenFeed (GF); C-Lock Inc., Rapid City, South Dakota) for one week. Steers were stratified by adaptation-period use of GF and randomly assigned to treatments within stratifications. Treatments were either 0, 0.9, 1.8, 2.7, 3.6, or 4.5 kg of WCS (as-fed) per day offered in individual feeding stanchions. Orts were measured and actual WCS intake was used in the analysis. Unshrunk body weight was measured weekly before feeding for the duration of the experiment. Mean supplement intake per animal ranged from 0.89 to 2.86 kg per day. Total fat content of the diet (WCS + forage) at the greatest WCS intake was estimated to be 6.4%. Animal performance increased linearly as WCS intake increased (P = 0.02). Two of the three steers assigned to the 0 WCS treatment refused to use GF, and therefore CH4 emissions were unavailable. Because only one observation was available at 0 WCS, and the Cook’s Distance of this point was greater than one (Di ≥ 7.48), the 0 WCS observation was excluded from further analysis. There tended to be a quadratic relationship between daily methane production (g of CH4 per animal per day) and WCS intake (P = 0.057), and there was a significant quadratic relationship between emission intensity (g of CH4 per kg of ADG) and WCS intake (P = 0.011) indicating minimum CFP at 2.0 kg WCS intake. The increased animal performance associated with WCS supplementation decreased emission intensity at moderate levels of supplementation. If ranchers choose to feed WCS to minimize emission intensity of steers grazing spring native range, they should feed approximately 2.0 kg per day of WCS. Key words: Enteric methane, whole cottonseed, beef cattle, grazing, GreenFeed