Characterizing Origin of Differences in Chemical Composition, Rumen Degradability, Intestinal Digestibility and Amino...

In tropical regions, protein is a critically limiting nutrient for dairy cow milk production, prompting the exploration of alternative protein sources. Brewery byproducts have been recognized for their wide use as valuable protein sources in ruminant nutrition. Traditional fermented beers are widely produced and consumed in Asia and Africa. This study evaluated the effects of heat treatment and cereal type to produce tella (Ethiopian traditional household beer) on crude protein (CP) and amino acid (AA) rumen degradability and intestinal digestibility of atella (a byproduct of tella). This was assessed by an in vitro simulation of the digestive process. Tella was prepared using a 0.25:0.03:0.02:0.70 ratio of maize or sorghum flour, barley malt, local hops, and water. Two tella types were produced: low-temperature-treated (109°C ± 9.4°C for 19 ± 4.8 min) and high-temperature-treated (159°C ± 16.1°C for 17 ± 2.9 min). Atella samples were incubated in an in vitro rumen simulation for 2, 4, 6, 10, 24, 48 and 72 h to assess dry matter (DM) and CP degradability. Intestinal digestibility was determined by exposure of the 10-h rumen residues to pepsin and pancreatic enzymes. Cereal type-dependent variations were observed (p < 0.05) in rumen degradation of DM, CP and AA, except for tryptophan. Heat treatment did not influence the ruminal degradation of DM, CP and AA, except for valine. Intestinal digestibility of bypass CP and all AA was affected (p < 0.05) by cereal type or heat treatment. Low-temperature-treated maize-derived atella showed higher total in vitro CP digestibility and intestinal digestibility of most AA compared to other atella types. Lysine and methionine were identified as primary and secondary limiting amino acids for milk protein production. Given the relatively high proportions of rumen undegradable protein in cereal-based atella diets, they should be balanced with feed ingredients high in rumen degradable protein.