Different feeding strategies can affect growth performance and rumen functions in Gangba sheep as revealed by integrated transcriptome and microbiome analyses

Abstract

Due to the harsh environment in the Tibetan Plateau, traditional grazing greatly limits the growth potential of local animals and causes severe ecosystem degradation. This is an urgent issue to be solved, which requires alternative strategies for grazing animals in the Tibetan alpine pastoral livestock systems. This study aimed to investigate the effects of different feeding strategies on growth performance and ruminal microbiota-host interactions in the local breed of sheep (Gangba sheep). Thirty 9-month old Gangba sheep (n = 10 per group) were assigned to natural grazing (G), semi-grazing with supplementation (T), and barn feeding (F) groups (supplementation of concentrate and oat hay) based on body weight. At the end of the experiment (75 d), all sheep were weighed, rumen fluid was obtained from six sheep per group, and ruminal epithelium was obtained from 3 sheep per group. The results showed that: (1) Compared with the G and T groups, the F group significantly increased dry matter intake, average daily gain, and feed conversion ratio of animals. Additionally, Gangba sheep in the F group had higher concentrations of ruminal short-chain volatile fatty acids (VFAs), especially propionate and butyrate (P <0.05) than sheep in the G and T groups. (2) The principal coordinates analysis indicated a significant difference in bacterial composition among different feed strategies. More specifically, the relative abundance of propionate (unidentified F082 and Succiniclasticum) and butyrate-producing (Eubacterium_coprostanoligenes_group) genera were also observed to be increased in the F group, in which unidentified F082 was identified as a differential biomarker among the three groups according to linear discriminant analysis effect size analysis. (3) The dynamics of the rumen epithelial transcriptome revealed that ECM-receptor interactions, focal adhesion, and PI3K-Akt signaling pathways, which are critical in mediating many aspects of cellular functions such as cell proliferation and motility, were upregulated in the F group. In conclusion, under harsh conditions in the Tibetan alpine meadow, barn feeding increased ruminal VFAs concentrations (especially propionate and butyrate), which stimulated gene expression related to cell proliferation in rumen epithelium, appearing to be superior to natural grazing and semi-grazing in gaining body weight of the local Gangba sheep.

Shift of Feeding Strategies from Grazing to Different Forage Feeds Reshapes the Rumen Microbiota To Improve the Ability of Tibetan Sheep (Ovis aries) To Adapt to the Cold Season

“…Firmicutes members play an important role in energy conversion, and the ratio of Firmicutes to Bacteroidetes in ruminants is strongly related to animal obesity and body fat storage ( 46 , 47 ). The variation in the microbial biota, directly related to available forage and forage quality, has been recorded in other herbivores grazing on the grassland ( 2 , 23 ). Under grazing conditions, Tibetan sheep need to consume their own energy to survive in a relatively harsh environment, while the barn environment is relatively comfortable and the range of activities is limited, thereby reducing energy consumption and helping to alleviate the phenomenon of fat loss.…”

“…As such, feeding strategy choice may provide a unique opportunity to manipulate the complex microbial ecosystem ( 22 ). Studies have demonstrated distinct rumen fermentation patterns of sheep switched from natural grazing to indoor feed depending on the feeding strategies (i.e., semigrazing with supplementation or barn feeding) ( 23 ). This difference in feeding strategies resulted in major changes in the nutrients ingested, especially fiber, water-soluble carbohydrates, and starch, and this also affected ruminants’ feed intake and gut microbiota.…”

Interrelation between gut microbiota, SCFA, and fatty acid composition in pigs

“…To our knowledge, there is no previous report of a relationship found between K00655 and butyrate, but interestingly, this KO was the one with the strongest negative correlation with a microbial genus, F082, which is a member of the order Bacteroidales. This genus also had a slight negative correlation with n-butyric acid and no significant correlation with propionic acid, although Bacteroidales F082 is considered a propionate producer in rumen ( 77 ), but its role in intestinal fermentation is not well defined yet.…”

Integration of Non-Coding RNA and mRNA Profiles Reveals the Mechanisms of Rumen Development Induced by Different Types of Diet in Calves

“…The dairy industry is an indispensable part of the national economy and is mainly based on natural grazing, semi-grazing and intensive farming. In the natural grazing and semi-grazing systems, due to the uncertainty of the ecosystem and environment, the DMI is low and ADF content is high in the diet, which reduces the efficiency of nutrient intake or absorption, and individual productivity cannot be fully developed [1]. Under foragebased livestock production systems, the quality and availability of feed determine the later growth and development of dairy cows [2].…”