Rumen and cecum bacteria of beef cattle that differ in feed efficiency fed a forage diet

Authors: Freetly, Harvey; Lindholm-Perry, Amanda

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/2023
Publication Date: 9/4/2023
Citation: Freetly, H.C., Lindholm-Perry, A.K. 2023. Rumen and cecum bacteria of beef cattle that differ in feed efficiency fed a forage diet. Journal of Animal Science. 101. Article skad292. https://doi.org/10.1093/jas/skad292.
DOI: https://doi.org/10.1093/jas/skad292

Interpretive Summary: Feed is one of the greatest costs associated with beef production. Modifying the efficiency that feed is used offers a potential mechanism to improve production efficiency. Microbes in the gastrointestinal tract modify the nutrient content of the feed cattle eat before it is absorbed. We have found that the microbiota along the gastrointestinal tract of cattle that differ in feed efficiency differs. These finding support the potential involvement of bacteria contributing to differences in feed efficiency.

Technical Abstract: Most of the research addressing feed efficiency and the microbiota has been conducted in cattle fed grain diets although cattle evolved to consume forage diets. Our hypothesis was that thebacteria in the rumen and cecum differed in cattle that have a common feed intake but had different average daily body weight gains (ADG) on a forage diet. Heifers (n = 134) were 606 ± 1 d of age and weighed 476 ± 3 kg at the start of the 84-d feeding study. Heifers were offered ad libitum access to a totally mixed ration that consisted of 86% ground brome hay, 10% wet distillers grains with solubles, and 4% mineral supplement as dry matter. Feed intake and body weight gain were measured, and gain was calculated. Heifers with the least (n = 8) and greatest (n = 8) ADG within 0.32 standard deviations of the mean daily dry matter intake were selected for sampling. Digesta samples from the rumen and cecum were collected and subsequent 16S analysis was conducted to identify Amplicon Sequence Variants. There were no differences in Alpha and Beta diversity between ADG classification within sample sites (P > 0.05). Both sample sites contained calculated balances of sister clades using phylogenetic isometric log-ratio transferred data that differed across ADG classification. These findings suggest that bacteria did not differ at the community level but there was structural difference at the clade level.