The effect of the inclusion of pea in lamb fattening concentrate on in vitro and in situ rumen fermentation.

Background: The objective of this study was to evaluate the effect of the proportion of pea (0%, 10%, 20%, and 30%), as a partial replacement for soybean meal (SBM) in the fattening concentrate, on ruminal fermentation in lambs. Gas and methane (CH ) production, in vitro dry matter degradability (IVDMD), ammonia (NH -N), and volatile fatty acid (VFA) production after 24 h of incubation were evaluated. The concentrates were also incubated in the rumen of the wethers for 2, 4, 6, 8, 12, and 24 h to evaluate the effects of pea inclusion on in situ dry matter degradability (DMD), organic matter degradability (OMD), nitrogen degradability (ND), NH -N, and VFA production.

Results: In the in vitro assay, the inclusion of pea only affected gas production (mL day degraded dry matter), CH production (mL day degraded dry matter), and IVDMD (P < 0.05), and tended to affect NH -N content (P < 0.10) without affecting VFA production. In the in situ assay, the inclusion of pea increased DMD, OMD, and ND linearly (P < 0.001), whereas pea inclusion decreased NH -N content linearly (P < 0.05). Neither total VFA production nor the proportion of acetic acid were affected by pea inclusion (P > 0.05), but the propionic proportion increased with the proportion of pea included.

Conclusions: The best level of pea inclusion in the concentrate could not be established based on the results of this study. However, the results showed that the inclusion of pea provides a good alternative protein source. © 2020 Society of Chemical Industry.