| This experiment was conducted to investigate the effects of sweetener and orange flavoring on feeding preference,growth performance and blood indexes of Holstein calves.Sixty healthy Holstein calves with similar birth weight(38.8±0.36 kg)were randomly divided into 4 groups with 15 replicates per group.The trial started with the calves at 3 days of age.The trial lasted for 63 days,and the calves were followed up for one week after weaning on day 56.1 There was no significant interaction between sweetener and orange fragrance supplementation on average daily feed intake of calves(P>0.05),but calves showed a great preference for orange fragrance supplementation during the whole feeding cycle(P<0.05).There was no significant interaction between sweetener supplementation and orange fragrance supplementation on body weight and average daily gain of lactating calves(P>0.05),but after weaning,average daily gain of calves in sweetener supplementation group was significantly higher than that in no sweetener supplementation group(P<0.05).At the end of the experiment,there was no significant difference in the body size of calves(P>0.05),but the body diagonal length and chest circumference of calves in the sweetener added group were significantly increased(P<0.05),and the body height of calves tended to increase(P=0.05).In addition,the abdominal circumference of calves tended to increase when orange fragrance was added at the 42nd day(P=0.06).2 On day 28,serum albumin content and white bulb ratio of calves in sweetener added group were significantly increased(P<0.05),serum total protein content had an increasing trend(P=0.07),and serum globulin content was significantly decreased(P<0.05);The serum globulin content of orange fragrance group was significantly increased(P<0.05),and urea nitrogen content had a tendency to decrease(P=0.06).On the 28th day,the total antioxidant capacity of the orange fragrance group was significantly increased(P<0.05),and the content of aspartate aminotransferase was significantly decreased(P<0.05).On the 28th day,the glucose content in the sweetener added group had an increasing trend(P=0.05).On the 56th day,the contents of total cholesterol and triglyceride in sweetener added group had an increasing trend(P=0.05).3 Sweetener and orange fragrance supplementation had no significant interaction with rumen pH,ammonia nitrogen,microbial protein total and total volatile fatty acid content,and had no significant interaction with rumen volatile acid ratio and the ratio of ethylene to propylene at 56 days.4 There was no significant interaction between sweetener and orange flavoring on rumen microbial Alpha diversity of calves at day 56.However,the Chaol index,Observed species index,Faith-pd index,Shannon index,Simpson index and Pielou_e index were significantly decreased in the observed species index adding orange fragrance group compared with the observed species index not adding orange fragrance group(P<0.05).Goods_coverage index was significantly increased(P<0.05).The interaction between sweeteners and orange fragrances on Tenericutes tended to decrease the abundance of bacterial flora(P=0.09).At the same time,compared with the group without orange fragrance,the abundance of Proteobacteria was significantly increased(P<0.05),while the abundance of Firmicutes was significantly decreased(P<0.05).The interaction with Succinivibrio was as follows:the bacterial abundance in the lusc group was significantly higher than that in the control group and sweetener group(P<0.05),but was significantly lower than that in the orange fragrance group(P<0.05).Compared with groups without sweeteners added,Butyrivibrio abundance is significantly increased(P<0.05).Compared with the group without orange fragrance addition,the abundance of Lachnobacterium could reduce(P=0.08).Compared with the group without orange fragrance addition,the abundance of Succiniclasticum and Olsenella could reduce.(P=0.09;P=0.07).5 Chaol index of sweet taste group was significantly higher than that in sweet taste group(P<0.05),but had no significant difference compared with control group and orange flavor group(P>0.05).The Goods_coverage index of sweet taste group was significantly higher than that of orange flavor group and sweet taste group(P<0.05),but there was no significant difference between sweet taste group and control group(P>0.05).There was no significant interaction between the addition of sweetener and orange fragrance on microflora level at day 56(P>0.05),but the abundance of cyanobacteria increased in sweetener group compared with no sweetener group(P=0.09),and the abundance of unclassified microflora decreased in orange fragrance group compared with no orange fragrance group(P=0.09).The interaction between sweetener and orange flavoring agent on Faecalibacterium could reduce the abundance of bacterium(P=0.08).The abundance of Prevotella in the sweetener added group was significantly lower than that in the no sweetener added group(P<0.05).In conclusion,We found that although lactating calves showed a better feeding preference for orange fragrance,it had limited effects on total starter intake and daily gain during lactation.For lactation calves,even though it has a high preference for feed,it has a limited effect on the total feed intake of starter since milk is the main food source during lactation period.However,it can influence the breeding of calves through its functional effect on body metabolism.The addition of feeding inducers in the starter diet improved the growth performance and antioxidant capacity of calves,alleviated liver damage,maintained the homeostasis of glucose and lipid metabolism in the body,optimized the structure of microbial flora in the rumen and intestine,and thus improved the health of calves.Therefore,orange flavoring and sweeteners may be suitable additives for lactation calves. |
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