Effect And Mechanism Of Creatine Pyruvate On Rumen Function Heat-stress In Beef Cattle

With the global warming,the heat stress of beef cattle becomes more and more serious during the summer high temperature and humidity season in southern my country,causing huge economic losses to beef cattle production enterprises.Therefore,how to alleviate heat stress in beef cattle has become a major concern for beef cattle nutritionists.The new functional nutrient pyruvate creatine(CrPyr)can be broken down into pyruvate and creatine in the body,both of which can be used as energy substrates and have antioxidant effects.This study intends to add CrPyr to beef cattle diets to explore the effect of pyruvate creatine on heat stress relief in beef cattle in summer,and analyze the rumen flora and flora protein function of heat-stressed beef cattle through 16 S rDNA sequencing and macroproteomics technology Changes to clarify the possible mechanism of CrPyr alleviating heat stress in beef cattle.Experiment 1 The effects of pyruvate creatine on blood index rumen fermentation and nutrient digestibility of beef cattle under heat stress were studiedIn this experiment,four 24-month-old,healthy Jinjiang bulls(400 ± 19 kg)of similar weight were selected for fistula surgery.Then,a 4×4 Latin square experimental design was used,and 0,20,40,and 60 g/d CrPyr were added to the diet.The test time was from July2 nd to September 3rd,2018.During the 64-day test period,the temperature-humidity index(THI)value in the barn was higher than 79 for 62 days,and the beef cattle were in a state of heat stress.The results showed that(1)With the increase of Cr Py addition(0 g/d to 60g/d),the body temperature of the test cattle presented a downward trend(P = 0.054).(2)With the increase of the amount of CrPyr,serum FT3 and T3 levels were significantly increased(P < 0.05),serum malondialdehyde,cortisol,corticosterone and lactate dehydrogenase activities were decreased(P < 0.05),and superoxide dismutase activities were increased(P < 0.05).(3)The addition of CrPyr in the diet could significantly increase the rumen microbial protein content,and the rumen p H value could be significantly increased in both 40 or 60 g/d CrPyr(P < 0.05).(4)The addition of 60 g/d CrPyr significantly improved the digestibility of crude fat,the content and excretion rate of allinol,total purine derivatives and microbial nitrogen flow in beef cattle(P < 0.05),and significantly reduced the urinary nitrogen excretion(P < 0.05).The above results indicated that adding CrPyr in the diet could improve the anti-stress and anti-oxidation ability of beef cattle under heat stress,and promote rumen fermentation.Supplementing CrPyr was an effective way to relieve the heat stress of beef cattle,and adding 60 g/d CrPyr under the conditions of this study had the best effect on the heat stress relief of beef cattle.Experiment 2 The effect of creatine dipyruvate on rumen microflora of beef cattle under heat stress was studiedIn this experiment,six 24-month-old Jinjiang bulls(405 ± 21 kg),healthy and similar in weight,were used for the experiment.The optimal additive dose selected in the first experiment was used,and two treatments were set at 0 g/d and 60 g/d.The test period is from August 2 to August 23,2019.During the 22-day test period,the THI value in the barn was higher than 79,and the beef cattle were in a heat stress state.The results showed that adding 60 g/d CrPyr to the diet of beef cattle(1)could significantly decrease the body temperature of beef cattle(P < 0.05),significantly increase the rumen p H value(P < 0.01)and the rumen microbial crude protein concentration(P < 0.05),and significantly improve the digestibility of crude fat and total nitrogen intake(P < 0.05).(2)There was no significant difference in-diversity index between the two groups.(3)At the portal level,the addition of CrPyr increased the relative abundance of Bacteroides bacteroides in gastric fluid of beef tumor(56.89% vs 54.08%),decreased the relative abundance of firmicelliphylum(38.35% vs 41.47%),and significantly reduced the relative abundance of Verrucomicrobiota.(4)At the level of genera,the addition of CrPyr increased the relative abundance of intestinal flora of The listeriaceae RC9(22.03% vs 19.63%),while decreased the relative abundance of Prevotella(8.57% vs 10.28%).The above results showed that the addition of CrPyr to the diet had a significant effect on the body temperature of beef cattle and improved the rumen internal environment.Although it had a significant effect on the rumen bacteriums,the proportion of the affected bacteria in the rumen was only about 1%,so the overall impact on the rumen microflora of heat-stressed beef cattle was not significant.Experiment 3 The effects of creatine tripyruvate on rumen microbial proteins of beef cattle under heat stress were studiedExperimental animals,feeding management and experimental design are the same as experiment II.The results showed that :(1)a total of 700 differential proteins were identified between the two groups(EG＿vs＿CG),including 121 significantly different proteins(67 up-regulated and 54 down-regulated)+373 quantified proteins only in EG group samples +206 quantified proteins only in CG group samples.(2)At the phylum level,the addition of CrPyr significantly reduced the relative abundance of bacteroidetes proteins in the gastric juice of heat stress beef tumor(P < 0.05),while the relative abundance of bacteroidetes proteins increased significantly(P < 0.05).(3)The addition of CrPyr could promote the fatty acid-oxidation,pyruvate metabolism,gluconeogenesis/glycolysis metabolism,tricarboxylic acid cycle and amino acid synthesis of rumen flora of beef cattle under heat stress.The above results indicated that the addition of CrPyr could change the protein expression of rumen flora of heat-stressed beef cattle,and promote the fatty acid-oxidation,pyruvate metabolism,gluconeogenesis/glycolysis metabolism,tricarboxylic acid cycle and amino acid synthesis of the rumen flora of heat-stressed beef cattle.Adding CrPyr diet can reduce the heat stress of beef cattle body temperature,improve crude fat digestibility,enhance oxidation resistance and function of rumen fermentation,promote the heat stress of beef cattle rumen bacteria beta oxidation of fatty acid,pyruvate metabolism,dysplasia/sugar glycolysis metabolism,the Krebs cycle and amino acid synthesis,help reduce oxidative stress,promote energy metabolism regulation,improve the heat stress condition of beef cattle rumen fermentation characteristics,and reduce heat stress.