Abstract
Using two successive types of diets (100% concentrate and 67% forage), this study explores the relationship between the ruminal microbiota of 78 Romane lambs and their feed efficiency (residual feed intake trait) or feeding behavior (feeding rate trait). Analysis was carried out phenotypically by correlating feed efficiency or feeding behavior traits with the relative abundance of bacteria at the phylum, family, and genus levels, and then genetically by comparing the microbiota of lambs selected for extreme breeding values for residual feed intake or feeding rate. Our results confirmed the major effect of diet on the ruminal microbiota composition. The microbiota of lambs consuming a forage-based diet was distinguished by higher microbial diversity and also by higher relative abundance of Firmicutes, whereas Bacteriodetes and Actinobacteria were relatively more abundant in the microbiota of lambs consuming a concentrate-based diet. Moreover, the comparison of lambs divergent for residual feed intake breeding values revealed that regardless of diet, more efficient lambs possessed a ruminal microbiota enriched in Coprococcus, Moryella, [Eubacterium] Brachy group, and [Eubacterium] hallii group, but depleted in Lachnospiraceae FD2005 and Shuttleworthia. The connection between microbiota composition and feeding rate was more tenuous, with no link between the abundance of particular genera and lambs genetically divergent for feeding rate.
Highlights
Feed efficiency is one of the most important phenotypic traits for animal farmers
The lambs grew an average of 402 ± 64 g/d and 113 ± 140 g/d to reach an average body weight (BW) of 52.6 ± 6.5 kg and 58.6 ± 13.6 kg at the end of the CAP and FAF periods, respectively
We did not notice an impact on microbial diversity, feed efficiency was linked with some ruminal microbial genera, bacteria involved in the degradation of aromatic compounds, nitrogen metabolism, and acetogenesis
Summary
Feed efficiency is one of the most important phenotypic traits for animal farmers. Residual feed intake (RFI) is the most commonly used method to estimate feed efficiency, defined as the difference between the true and estimated feed intake of animals according to their body weight (BW), average daily gain (ADG), and body composition. Selecting animals for feed efficiency is a strong lever for agroecological breeding. Ruminal Microbiota of Romane Lambs ruminal digestion and the ruminal microbiome (Løvendahl et al, 2018). The latter plays a central role in the nutrition of its host from a digestive and metabolic point of view, which directly affects feed efficiency. The ruminal microbiota provides an opportunity to control feed efficiency through dietary manipulation (Malmuthuge and Guan, 2017), which can be applied by farmers. Understanding host-ruminal microbiota interactions is crucial for improving farming efficiency
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