Growth And Development,Meat Quality,Gastrointestinal Bacteria Of Grazing And Drylot Raised Tibetan Goat

The gastrointestinal microbiota plays an important role for healthy and immunity of host.Some research have linked the gastrointestinal microbiota with microbiota by intestinal-renal axis,brain-intestinal axis,liver-intestinal axis.The feeding method also had a significant effect on gastrointestinal microorganisms However,most studies concentrated on the effects of feeding methods on composition and diversity of ruminant gastrointestinal microbiota,and rarely made use of metagenome to further study the functional gene of microbiota.In this study,a total of fifty half-sib Tibetan goat kids(n = 25 each)were subjected to divided into two groups.After feeding by grazing or drylot for 365 days,a total of ten one-year-old(n = 5 each)were selected from the two feeding groups and were slaughter to collect serums,longissimus dorsi,gastrointestinal tissues,mucosas and contents.Serum physiological and biochemical indicators,meat quality indicators of the longissimus dorsi,gastrointestinal histologic morphology and Carbohydrate-Active enzymes genes,antibiotics resistance genes(ARGs)and methane metabolism genes of gastrointestinal microbiota were measured to deeply and comprehensive investigate the effects of feeding method(grazing VS.drylot)on Tibetan goats.1.There were no significant difference in birth weight between grazing(2.34 ± 0.08kg)and drylot(2.31 ± 0.05kg)group(P > 0.05).However,the slaughter weight was higher in drylot group(21.84 ± 1.14kg)than grazing group(14.7 ± 0.94kg)(P < 0.05);serum albumin and glucose concentrations,which presented protein and energy absorption for host,were significantly higher in the drylot group(P < 0.05);serum phosphorus and magnesium levels were significantly higher in drylot group(P < 0.05);and yet there were no significant difference for serum immunity indexes between two groups(P < 0.05).Illustrate: compared with grazing group,the growth rate and nutrient absorption capacity significantly improved in drylot raised goats.However,there were no significant difference immunologic function between two groups for serum indexes.2.Compared with grazing group,the intermuscular fat content was significantly higher in drylot raised goats(P < 0.05);the total fatty acids and polyunsaturated fatty acids(PUFA)contents were significantly higher in drylot raised goats(P < 0.05).Illustrate: compared with drylot group,the nutritional value of mutton was increased but the fat content was decreased in grazing raised goats.3.Compared with drylot group,the ruminal papilla height were significantly lower(P < 0.05),but the ruminal papilla width and cuticle thickness were significantly higher in grazing raised goats(P < 0.05);the duodenum villi height/ crypt depth and muscular thickness were significantly higher in grazing raised goats(P < 0.05).Illustrate: due to intake of roughage,mechanical digestion for forage in rumen and nutrient absorption capacity in duodenum enhanced in grazing raised goats.4.In terms of microbiota diversity,ruminal microbiota diversity was significantly higher than cecum and colon(P < 0.05),lumen microbiota diversity was significantly higher than mucosa(P < 0.05).Compared with grazing group,rumen microbiota were significantly lower but cecum and colon microbiota diversity were significantly higher in drylot raised goats(P < 0.05);in terms of microbiota composition,Methanobrevibacteria was significantly enriched in rumen of drylot raised goats(P < 0.05),Alistipes was significantly enriched in rumen of grazing raised goats.Notably,Methanobrevibacteria and Alistipes were competitively inhibited relation in network.Prevotella was significantly enriched in cecum and colon of drylot raised goats(P < 0.05),Clostridium as significantly enriched in cecum and colon of grazing raised goats(P < 0.05);in terms of microbiota functional gene,in the goats rumen the microbiota gene involved in methane-hydrogen nutrient metabolism enzyme were enriched in drylot raised goats(P < 0.05),the microbiota gene involved in cellulose metabolism enzyme were enriched in grazing raised goats(P < 0.05).In the hindgut,antibiotic resistance genes(ARGs)and plants cell wall degradation enzymes gene were significantly enriched in drylot raised goats(P < 0.05),DNA process enzyme gene and bacitracin gene which all related to immunity were significantly enriched in grazing raised goats(P < 0.05).Illustrate: in drylot raised goats,due to the intake of high-grain diets,rumen microbiota involved in the degradation of digestible carbohydrates(starch)and the structural carbohydrates were metabolized in hindgut.While in grazing raised goats,rumen microbiota mainly involved in the cellulose degradation and hindgut microbiota mainly involved in body immunity.Taking together,the feeding method(drylot vs.grazing)exerted significant influence on the growth and development,body immunity,meat quality,gastrointestinal tissues and microbiota community.This study would provide a valuable reference for the scientific and efficient breeding of livestock in plateau.At the same time,rumen and hindgut microbiota play an essential role for maintaining immunity,especially for grazing livestock living in extreme environments on the plateau.