Effect of partially protected butyrate used as feed additive on growth and intestinal metabolism in sea bream (Sparus aurata).

Butyrate is a short-chain fatty acid extensively used in animal nutrition since it promotes increases in body weight and other multiple beneficial effects on the intestinal tract. Although such effects have been demonstrated in several species, very few studies have assessed them in fish. On the other hand, little is known about the metabolic processes underlying these effects. In the present work, growth parameters and changes in more than 80 intestinal metabolites (nucleotides, amino acids and derivatives, glycolytic intermediates, redox coenzymes and lipid metabolism coenzymes) have been quantified in juvenile sea bream fed a butyrate-supplemented diet. Results showed a significant increase in the weight of fish receiving butyrate, while metabolomics provided some clues on the suggested effects of this feed additive. It seems that butyrate increased the availability of several essential amino acids and nucleotide derivatives. Also, the energy provision for enteric cells might have been enhanced by a decrease in glucose and amino acid oxidation related to the use of butyrate as fuel. Additionally, butyrate might have increased transmethylation activity. This work represents an advance in the knowledge of the metabolic consequences of using butyrate as an additive in fish diets.

Effects of bioethanol plant and coproduct type on the metabolic characteristics of the proteins in dairy cattle.

The dramatic increase in bioethanol production in Canada has resulted in millions of tonnes of different types of coproducts: wheat dried distillers grains with solubles (DDGS), corn DDGS, and blend DDGS (e.g., wheat:corn 70:30). The objectives of this study were 1) to investigate the effect of DDGS type and bioethanol plant on the metabolic characteristics of the proteins and the total truly digested and absorbed protein supply to dairy cattle using the DVE/OEB system and 2) to compare the metabolic characteristics of the proteins of original feedstock grains with their respective derived DDGS samples. The results showed that all types of DDGS are a good source of the truly digested and absorbed protein in the small intestine [DVE; 107 vs. 249 g/kg of dry matter (DM) for wheat and wheat DDGS; 108 vs. 251 g/kg of DM for corn and corn DDGS]. According to the DVE/OEB system, the predicted total DVE supply to dairy cattle differed among wheat DDGS (DVE=249 g/kg of DM), corn DDGS (DVE=251 g/kg of DM), and blend DDGS (DVE=281 g/kg of DM) and, to a lesser extent, between the different bioethanol plants (DVE: 277 vs. 230 g/kg of DM for bioethanol plants 1 and 2). The results indicated the superior protein value of blend DDGS as well as that of the more optimum degraded protein balance (DPB) value for corn DDGS (DPB: 11 g/kg of DM in corn DDGS vs. 72 g/kg of DM in wheat DDGS and 55 g/kg of DM in blend DDGS). In addition, differences in the acid detergent-insoluble crude protein content of wheat DDGS samples were reflected in differing protein DVE values. In conclusion, it is inappropriate to assume fixed protein values for DDGS without considering factors such as DDGS type and bioethanol plant origin.