Alternative Feeding Resources in the Mediterranean areas to mitigate methane emissions from sheep

The objective of the present doctoral study is to evaluate the potential of using two locally byproducts namely carob pulp (Ceratonia Siliqua) and dehydrated citrus pulp (DCP) in view of reducing the carbon footprint, alleviating methane gas emission and reducing dependence on cereal feeding in fattening lambs. Two experimental trials were set up in parallel in an experimental farm in Villarosa (EN) both with Comisana lambs at 90 days of age. Two level of inclusion i.e. 24% and 35% fresh weight were investigated. Four types of parameters were monitored namely performance and productivity both in vivo and at slaughter, rumen pH and fatty acids, rumen microbial ecosystem and in vitro fermentation kinetics. It was found that both carob pup and DCP ingesting animals had similar performance and productivity. The feed conversion ratio (FCR) was 0.25 for all the diets and the carcass weight was 43%.The rumen pH was similar across all the diets being around 6.6 which is within the range for optimal ruminal metabolism. For the rumen fatty acids profile, it was found that only vaccenic acid was significantly affected by ingestion of DCP, being at 4.99% in the 35% DCP containing diet (Cp35) compared to 1.5% in the control group. For the carob ingesting animals, the diet affected only the stearic acid which was lower in the 35% ingesting animals (Ca35) i.e. 26.4% compared to 38.3% in the control. These values demonstrate to some extent a change in the fatty acids metabolism due to ingestion of the two by products. The rumen microbial ecosystem was not affected by inclusion of the byproducts remaining at a level of 11 (logcopies/gFM) for total bacteria. It was found also that the in vitro methane production was similar across all the diets demonstrating that inclusion of Carob pulp or DCP did not change methanogenesis. The results of this study, demonstrated that Carob pulp and DCP can be used to substitute barley to some extent without any effect on performance and methane emission in lamb fattening. Rumen metabolism, in terms of ruminal fluid fatty acids, would seem affected only by dietary treatments based on the highest proportions (35%) of the two by products investigated.