Location: Livestock Nutrient Management ResearchTitle: Effects of protein supplementation to steers consuming low-quality forages on greenhouse gas emissions
|SHRECK, ADAM - Feedlot Health Management Services|
|ZELTWANGER, JOSH - University Of Missouri|
|BAILEY, ERIC - University Of Missouri|
|JENNINGS, JENNY - Texas A&M Agrilife|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/27/2021
Publication Date: 5/5/2021
Citation: Shreck, A.L., Zeltwanger, J.M., Bailey, E.A., Jennings, J.S., Meyer, B.E., Cole, N.A. 2021. Effects of protein supplementation to steers consuming low-quality forages on greenhouse gas emissions. Journal of Animal Science. skab147. https://doi.org/10.1093/jas/skab147.
Interpretive Summary: The quality of grazed forages decreases as they mature and frequently, they become deficient in nutrients of importance to beef cattle. In typical production systems protein may be supplemented, especially during the winter, when forages become deficient in protein and energy. Provigin supplemental protein routinely increases the digestibility of forages and results in increased forage intake and increased animal productivity. In this study we examined the effects of feeding two different protein supplements (either cottonseed meal or dried distillers grains with solubles) on forage intake, diet digestibility, and enteric methane production. As expected, providing protein supplementation increased forage intake but did not affect total digestibility. Due to greater forage intake, enteric methane production was increased with protein supplementation, however the quantity of methane produced per unit of forage intake was decreased. Results of this study indicate that the routine practice of supplementing cattle with protein when grazed forages are deficient in protein will lower the carbon-footprint of cattle production.
Technical Abstract: Providing supplements that enhance the efficiency of feed utilization can reduce methane (CH4) emissions from ruminants. Protein supplementation is widely used to increase intake and digestion of low-quality forages, yet little is known about its impact on CH4 emissions. British-cross steers (n = 23; Initial BW = 344 ± 33.9 kg) were used in a three-period crossover design to evaluate the effect of protein supplementation to beef cattle consuming low-quality forage on ruminal CH4, metabolic carbon dioxide (CO2) emissions, forage intake, and ruminal fermentation. Steers individually had ad libitum access to low-quality bluestem hay [4.6% crude protein (CP)] and were provided supplemental protein based on [dry matter (DM) basis]: cottonseed meal (CSM; 0.29% of body weight (BW) daily; 391 g/d CP), dried distillers grains with solubles (DDGS; 0.41% of BW daily 563 g/d CP), or none (CON). Urea was added to DDGS to match rumen degradable protein provided by CSM. Ruminal CH4 and metabolic CO2 fluxes were obtained 2.4 ± 0.4 times/steer daily using an automated open-circuit gas quantification system (GreenFeed emission monitoring system; C-Lock Inc., Rapid City, SD). Forage intake increased (P < 0.01) with protein supplementation; however, no difference in forage intake (P = 0.14) was observed between CSM and DDGS treatments. Flux of CO2 (g/d) was greater (P < 0.01) for steers fed CSM and DDGS than for steers fed CON probably due to greater DMI. Steers supplemented with CSM had greater (P < 0.01) CH4 emissions (211 g/d) than DDGS (197 g/d) both of which were greater (P < 0.01) than CON (175 g/d ). Methane emissions as a proportion of GE intake (Ym) were lowest (P < 0.01) for DDGS (7.66%), intermediate for CSM (8.46%) steers, and greatest for CON (10.53%). Steers fed DDGS also had the lowest (P < 0.01) ruminal acetate:propionate ratio (3.60) whereas CSM (4.89) was intermediate, and CON (5.64) steers were greatest (P < 0.???). This study suggests that the common practice of supplementing protein to cattle consuming low-quality forage decreases GHG emissions per unit of GE intake.