Effects of Donor diets, breed and increasing level of supplementation on in vitro gas production parameters

Abstract

In vitro fermentation studies were undertaken to evaluate the effects of donor diets and breeds on fermentation parameters. Rumen fluid from 3 N’Dama and 3 crossbred donor animals was used for 24 hour in vitro fermentations. The donor animals were fed consecutively the same three diets Baby corn Stover plus concentrate (BCS:Co), Groundnut hay plus concentrate(GNH:Co) and Groundnut hay plus moringa(GNH:Mo) at 20% level of supplementation. Each of these inocula was incubated with substrates consisting of BCS:Co, GNH:Co and GNH:Mo at 5 levels of supplementation, plus supplement alone. The breed of the donor animals did not significantly affect 24 hour gas production, but short chain fatty acid concentration was higher with rumen fluid from crossbreds when donors were fed BCS:Co and GNH:Mo. Moringa meal as supplement to donor animals changed the fermentation pattern of all the substrates, such that gas production and SCFA increased substantially in groundnuthay based substrates, whereas gas production of BCS:Co substrates decreased and SCFA did not substantially change. In vitro digestibility was higher with rumen fluid from N’Dama whatever the diet of donor animals and the substrate incubated. Thus, when testing a supplementation strategy in vitro, it should be important that donor animals are fed the same components (roughage and supplement) that will be combined at different levels in vitro, whilst the breed of donor animals may be of second importance. This work provides conclusive evidence that in vitro incubations may be used to design supplementation strategies, thus reducing the need for in vivo experiments.