Presentation Title

The rumen metaproteome of dairy cows is affected by dietary fiber and starch content

Presenter's Name(s)

Bharath MulakalaFollow

Project Collaborators

K. Smith, M. Snider, A. Ayers, M. C. Honan, and S. L. Greenwood

Abstract

Dietary starch and fiber are key components within the carbohydrate fraction of ruminant diets. Starch and fiber content impact microbial diversity and could also affect the ruminal microbial profiles and fermentation products; however, there is no information about their effect on ruminal microbial metabolic activity. The aim of our study was to characterize the rumen metaproteome in cows fed different levels of physically effective undegradable neutral detergent fiber (peuNDF240) and rumen fermentable starch (RFS). Eight lactating cannulated Holstein cows were assigned to the study as part of a 4 × 4 Latin square design with a 2 x 2 factorial treatment design. The experiment consisted of four 28-d periods, cows were paired randomly at the beginning of each period, and then each pair were randomly assigned to one of the four following treatments: 1) low peuNDF240, low RFS, 2) high peuNDF240, low RFS, 3) low peuNDF240, high RFS, and 4) high peuNDF240, high RFS. Rumen fluid samples were collected at three time points (06h00, 10h00, and 14h00) from each cow across d 27 and 28 of each period. Samples were then pooled within cow within the period, creating one composite sample per cow per period, and the microbial protein fraction was isolated and subsequently analyzed using LC-MS/MS techniques. Normalized data were analyzed for the impact of diet on microbial protein abundances using the MIXED procedure of SAS. In total, 138 proteins from 22 different microbial species were identified. Of these, 28 proteins from 12 different microbial species were affected by the treatment. Out of 28 proteins, 21 were affected by RFS content, with 15 proteins having a higher abundance with higher dietary RFS. Additionally, 7 proteins were affected by dietary peuNDF240 content (2 proteins) or the interaction of peuNDF240 and RFS (5 proteins). Proteins involved in glycolysis, gluconeogenesis, protein biosynthesis, and carbon metabolism were among the functional proteins most affected. These results indicate that fiber and starch inclusion levels in the diet affect the core microbial metabolic pathways. This research contributes to the body of knowledge characterizing dietary mechanisms' influence on the core rumen microbial metabolism and performance.

Keywords: starch, fiber, rumen metaproteome.

Primary Faculty Mentor Name

Sabrina Greenwood

Status

Graduate

Student College

College of Agriculture and Life Sciences

Program/Major

Animal, Nutrition and Food Sciences

Primary Research Category

Food & Environment Studies

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The rumen metaproteome of dairy cows is affected by dietary fiber and starch content

Dietary starch and fiber are key components within the carbohydrate fraction of ruminant diets. Starch and fiber content impact microbial diversity and could also affect the ruminal microbial profiles and fermentation products; however, there is no information about their effect on ruminal microbial metabolic activity. The aim of our study was to characterize the rumen metaproteome in cows fed different levels of physically effective undegradable neutral detergent fiber (peuNDF240) and rumen fermentable starch (RFS). Eight lactating cannulated Holstein cows were assigned to the study as part of a 4 × 4 Latin square design with a 2 x 2 factorial treatment design. The experiment consisted of four 28-d periods, cows were paired randomly at the beginning of each period, and then each pair were randomly assigned to one of the four following treatments: 1) low peuNDF240, low RFS, 2) high peuNDF240, low RFS, 3) low peuNDF240, high RFS, and 4) high peuNDF240, high RFS. Rumen fluid samples were collected at three time points (06h00, 10h00, and 14h00) from each cow across d 27 and 28 of each period. Samples were then pooled within cow within the period, creating one composite sample per cow per period, and the microbial protein fraction was isolated and subsequently analyzed using LC-MS/MS techniques. Normalized data were analyzed for the impact of diet on microbial protein abundances using the MIXED procedure of SAS. In total, 138 proteins from 22 different microbial species were identified. Of these, 28 proteins from 12 different microbial species were affected by the treatment. Out of 28 proteins, 21 were affected by RFS content, with 15 proteins having a higher abundance with higher dietary RFS. Additionally, 7 proteins were affected by dietary peuNDF240 content (2 proteins) or the interaction of peuNDF240 and RFS (5 proteins). Proteins involved in glycolysis, gluconeogenesis, protein biosynthesis, and carbon metabolism were among the functional proteins most affected. These results indicate that fiber and starch inclusion levels in the diet affect the core microbial metabolic pathways. This research contributes to the body of knowledge characterizing dietary mechanisms' influence on the core rumen microbial metabolism and performance.

Keywords: starch, fiber, rumen metaproteome.