Effect Of Triticale Hay On Growth Performance,Digestive Metabolism,Blood Indexes And Fecal Microbial Diversity Of In Holstein Breeding Cattle

Objective:As an new fodder crop with a higher nutritional value than other grasses,triticale is a good source of roughage for ruminants and has great potential for development.Current research on triticale is still mainly focused on assessing its nutritional value as a high quality forage grass,with less exploration of animal feeding,leaving livestock still to be fed traditional roughage,which is costly and cannot be adapted to local conditions.This experiment therefore investigates the forage value of triticale hay through animal feeding,providing a theoretical basis for its use as a high quality roughage and its widespread use in ruminant farming.Methodology:Experiment 1:A one-way completely randomised experimental design was used to replace alfalfa hay and wheat straw in the fermentation substrate with 0%（GroupⅠ）,25%（GroupⅡ）,50%（GroupⅢ）,75%（GroupⅣ）and 100%（GroupⅤ）of triticale hay.The effects of different replacement ratios on the rumen fermentation characteristics of ruminants were initially assessed by analysing gas production and kinetic parameters,fermentation parameters and dry matter degradation rates.Experiment 2:Under the same feeding conditions,30 healthy,physiologically sound Holstein breeding cattle aged 10 months with an average weight of（325±20.0）kg were selected and randomly divided into three groups of 10 cattle each,with one replicate for each group.The cattle in T1 group was fed the basal diet（alfalfa hay:wheat straw=1:1）,and in groups T2 and T3,50%（alfalfa hay:wheat straw:whole plant triticale hay=0.5:0.5:1）and 100%（all whole plant triticale hay）hay of the basal diet were replaced by whole plant of triticale hay,respectively.The pre feeding period was 7 days,and the trial period was 66 days.Experiment 3:Before the morning feed on day 66 of the trial period,six Holstein breeding cows were randomly selected from each group and approximately 30 g of fresh faeces were taken from the rectum and stored at-80℃.Four further faecal samples were randomly selected from each group and tested by Meguiar’s using the Illumina Miseq platform.The diversity of faecal flora and the correlation of flora with apparent digestibility and rumen fermentation parameters were analysed.Results:The results of experiment 1 showed that the total gas production of groupⅢwas significantly higher than that of groupsⅣandⅤat 48 h of in vitro fermentation by 19.89 m L and 21.25 m L,respectively（P<0.05）,and the gas production rate of groupⅢwas slightly higher than that of other groups at each fermentation time.The fast gas production,slow gas production and potential gas production of groupⅢwere the highest.At 24 h and 48 h,DMD in groupⅢwas significantly higher than that in groupsⅣandⅤ（P<0.05）.At 48 h of fermentation,there were no significant differences in p H,TFVA,propionic acid,butyric acid and A/P in all treatment groups（P>0.05）,but the acetic acid concentration was significantly higher than that in groupsⅠandⅤ（P<0.05）.The results of experiment 2 showed that there were no significant differences in body weight and daily gain among all groups（P>0.05）.The ratio of feed to gain in T3 group was significantly higher than that in T1 group（P<0.05）.The apparent digestibility of dry matter（DM）,organic matter（OM）and crude protein（CP）in T2 group was not significantly different from that in T1 group（P>0.05）,but was significantly higher than that in T3 group（P<0.01）.The apparent digestibility of neutral detergent fiber（NDF）and acid detergent fiber（ADF）in T2 group was significantly higher than that in T3 group（P<0.05）,and extremely significantly higher than that in T1 group（P<0.01）.There were no significant differences in the contents of glucose（GLU）,triglyceride（TG）,total cholesterol（TC）,total protein（TP）,high density lipoprotein cholesterol（HDL-C）and low density lipoprotein cholesterol（LDL-C）in serum of growing cattle among all groups（P>0.05）.The concentration of bovine serum albumin（ALB）in T3 group was significantly higher than that in T1 and T2 groups（P<0.01）.The content of bovine serum urea nitrogen（UN）in T2 group was significantly lower than that in T1 group（P<0.05）,but had no significant difference with that in T3 group（P>0.05）.There were no significant differences in rumen p H,total volatile fatty acids（TVFA）,contents of acetic acid,propionic acid,butyric acid and acetic acid/propionic acid（A/P）among all groups（P>0.05）.Rumen NH₃-N concentration in T3 group was significantly higher than that in T2 group（P<0.05）,but no significant difference was found between T3 group and T1 group（P>0.05）.Rumen microbial protein（MCP）content in T3 group was significantly lower than that in T2 group（P<0.05）.The results of experiment 3 showed that the Shannon index,Ace index and Chao index of Holstein dung microflora in T2 group were not significantly different from those in T1 and T3 groups（P>0.05）.At the level of fecal microflora,Firmicutes and Bacteroidetes were the main dominant bacteria groups.The proportion of Proteobacteria and Actinobacteriota in T3 group was significantly higher than that in T2group（P<0.05）.The dominant bacteria genera at the genus level were UCG-005,Christensenellaceae R-7group,Monoglobus and Rikenellaceae RC9 gut group,but there was no significant difference among all groups（P>0.05）.Conclusion:In vitro fermentation tests initially demonstrated that replacing 50%of the alfalfa hay and wheat straw in the ration with whole triticale hay had the best effect on rumen fermentation performance and,in animal feeding tests,improved growth performance,serum biochemical parameters,rumen fermentation and significantly increased nutrient digestibility in the ration of Holstein finishing cattle.In addition,the addition of triticale hay improved the richness and biodiversity of the Holstein cattle intestinal flora,which is more beneficial to the intestinal health of Holstein breeding cattle.