PSI-2 Evaluation of feed by-products on in vitro DMD, methane production and ruminal fermentation parameters

Abstract

Abstract In-vitro batch culture assessment was used to examine DMD, ruminal fermentation parameters and CH4 production associated with a range of by-products feeds including pea hulls, pea screenings, soybean, soybean meal, wheat bran, wheat screenings, wheat DDGS, wheat corn DDGS, corn DDGS, coarse hemp powder, hemp hulls, flax screenings, nexera canola, commodity canola, sunflower screenings, quinoa and dogwood in a randomized complete block design. By-products were obtained from various locations across Manitoba at 3 monthly timepoints to account for sample variability. By-products (0.5g DM) were weighed individually into jars and incubated at 39°C in jars containing buffered medium and rumen fluid for 48 hrs. Gas samples were collected at 3,6,9,12,18,24,36 and 48 hr and CH4, DM disappearance, pH, VFA and ammonia concentrations were measured. Data were analysed using the MIXED procedure of SAS including treatment as a fixed effect and run, block, month and location as random effects. Methane output was regressed on CP and NDF to determine the effect of these constituents. Treatment had a significant effect (P < 0.0001) on CH4 (ml/g DMD) produced, with dogwood having the lowest cumulative CH4 (11.13 ml/g DMD) compared to all other treatments. Methane (ml/g DMD) decreased (P < 0.0005) as pH decreased. An inverse relationship between protein and CH4 was apparent, which explained 31% (R2= 0.31) of the CH4 (ml/g DMD) produced. Further, NDF (%) had a significant effect (P < 0.0001) on CH4 and explained 25% (R2=0.25) of the CH4 (ml/g DMD) produced. Overall, by-products higher in crude protein and lower in NDF produced lower (P < 0.001) CH4 ml/g DMD. Although the addition of dogwood to cattle diets is novel, it does show potential CH4 mitigation potential using in vitro assessment.