In vitro rumen degradation, fermentation, and methane production of five bakery by-products

Christodoulou, C. ORCID: https://orcid.org/0000-0001-9465-3886, Jalal, H., Crompton, L. A., Kliem, K. E. ORCID: https://orcid.org/0000-0002-0058-8225, Davison, N., Smith, L. G. ORCID: https://orcid.org/0000-0002-9898-9288, Humphries, D. J., Fusaro, I. and Stergiadis, S. ORCID: https://orcid.org/0000-0002-7293-182X (2026) In vitro rumen degradation, fermentation, and methane production of five bakery by-products. Animal Feed Science and Technology. ISSN 0377-8401 doi: 10.1016/j.anifeedsci.2026.116913 (In Press)

Abstract/Summary

Utilising bakery by-products (BBPs) in ruminant diets could promote circularity and waste management. This study aimed to investigate the effect of different BBPs, specifically wholemeal crumbed bread (WMB), white crumbed bread (WB), plain cracker feed (CF), flavoured cracker feed (FCF), and biscuit meal (BM), on rumen degradability, fermentation characteristics, and methane (CH4) emissions by employing a 72-h in vitro gas production system. The basal substrate consisted of dried, ground grass silage, wheat, and dried corn distillers’ grains, while the BBPs mainly and partially replaced wheat grain, and in the case of WMB, WB, FCF, and BM soyabean meal as well. Fermentation kinetics were determined by fitting gas and CH4 production curves to nonlinear models. In vitro dry matter degradability (IVDMD) was lower (P = 0.007) in WMB and FCF compared with CON. Propionate concentration was higher (P < 0.001) in WMB, WB, CF, and BM than in CON, whereas valerate concentration was higher (P = 0.004) in WMB and WB compared with the other treatments. The acetate:propionate and (acetate+butyrate)/propionate ratios were greater (P < 0.001) in CON than in WMB, WB, CF, and BM. Total gas production kinetics also differed, with the fractional rate constant being higher (P < 0.001) in WB and BM compared with CON, and the half-life being longer (P < 0.001) in CON than in the BBPs treatments. The partitioning factor was highest in CON and lowest in CF (P < 0.05). The asymptotic CH4 production was higher in CON than in WB, FCF, and BM. In terms of fermentation kinetics, the fractional rate constant of CH4 production was higher in WB than in CON and WMB, while the half-life of fermentation of the degradable fraction of each substrate was longer in CON than in WB, CF, FCF, and BM. However, the CH4 yield expressed per unit of DM degraded did not differ significantly among treatments (P > 0.05). The inclusion of WMB and BM, although resulting in lower IVDMD, was associated with higher propionate concentrations, indicating a shift in fermentation pattern. Despite no effect on cumulative CH4 yield, WB and FCF altered fermentation kinetics, indicating differences in modelled CH4 production patterns rather than in total CH4 yield.

Item Type	Article
URI	https://centaur.reading.ac.uk/id/eprint/130665
Identification Number/DOI	10.1016/j.anifeedsci.2026.116913
Refereed	Yes
Divisions	Life Sciences > School of Agriculture, Policy and Development > Department of Animal Sciences Life Sciences > School of Agriculture, Policy and Development > Centre for Dairy Research (CEDAR) Life Sciences > School of Agriculture, Policy and Development > Department of Agri-Food Economics & Marketing
Publisher	Elsevier
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