| This experiment studied the effects of adding rare earth citrate on the growth performance,slaughter performance,blood index,meat quality,fat metabolism,ruminal fermentation and microbial community structure of Jinjiang cattle through feeding and slaughtering experiments.To investigate the effect of body mechanism and the appropriate add production levels of rare earth citrate were obtained.The experiment can be divided into four parts.Experiment 1:The purpose of this experiment was to investigate the effects of rare earth citrate on growth performance and nutrient digestibility of male Jinjiang cattle.A total of 24 heads of 18 months old Jinjiang bulls with the similar age and average weight(374.75±4.02)kg were randomly divided into 4 groups.The addition level of rare earth citrate in diets was 0 mg/kg(Control group),400 mg/kg,800 mg/kg,1200 mg/kg,respectively.The experiment had 10 days pre-feeding period and 60 days formal period.The results showed that:(1)On growth performance,the average daily gain of 400 mg/kg?800 mg/kg treatment group was significantly higher than that of the control group(P<0.05),and increased by 53.03%and 46.97%,respectively.The feed gain ratio of 400 mg/kg.800 mg/kg treatment group was significantly lower than that of the control group(P<0.05),and decreased by 24.00%and 21.92%,respectively.(2)nutrient substance apparent digestibility:The apparent digestibility of neutral detergent fiber in the diets added with 400 mg/kg and 1200 mg/kg rare earth citrate was significantly higher than that of the control group(P<0.05),There was no significant difference between three treatment groups in the apparent digestibility of neutral detergent fiber(P>0.05).There was no significant difference in the apparent digestibility of dry matter,organic matter,crude protein and acid detergent fiber between each groups(P>0.05).In summary,the addition of rare earth citrate in the diet can improve the growth performance and apparent digestibility of Jinjiang cattle,but it has no significant effect on the feed intake,and 400 mg/kg rare earth citrate added in the diet is the best.Experiment 2:This experiment aimed to explore the effects of rare earth citrate on the biochemical,antioxidant,immune and endocrine factors in Jinjiang cattle blood.The rearing test was the same as experiment one,collect blood at the end of the experiment and measure the corresponding indicators.The results showed that:(1)The diet with 400 mg/kg rare earth citrate of Jinjiang cattle can significantly increase the content of density lipoprotein cholesterol in serum(P<0.05),and significantly decrease the content of urea nitrogen in serum(P<0.05).(2)1200 mg/kg high dose of rare earth citrate in the diet could significantly increase the content of MDA in serum(P<0.01),and significantly decreased the level of GSH-Px(P<0.05).While the low dose of 400 mg/kg rare earth citrate could significantly increase the level of T=AOC(P<0.05).(3)The rare earth citrate added into the diet had no significant effect on the immune indicators(P>0.05).(4)400 mg/kg low dose of rare earth citrate added into the diet could significantly increase the levels of GH and leptin in serum(P<0.05).The above results showed that 400 mg/kg low dose of rare earth citrate can promote the steady state of body internal environment,improve the antioxidant capacity,and has a positive effect on the growth hormone and the secretion of leptin,which inhibits fat deposition.promote the growth of the body and inhibit the fat synthesis factor.And 1200 mg/kg high dose of rare earth citrate had a negative impact on antioxidant to the body.Experiment 3:The aim of this study was to investigate the effects of rare earth citrate on rumen fermentation parameters and rumen microbial flora structure of Jinjiang cattle.According to the previous research results,three cattles close to the average weight in the control group and the 400mg/kg group were slaughtered in the experiment one.the samples of rumen fluid were collected after slaughter.The rumen bacteria structure and diversity were determined by Miseq high-throughput sequencing technique.The results showed that:(1)the addition of rare earth citrate in the diet had no significant effect on the content of pH,NH3-N,total VFA,acetic acid and butyric acid in the rumen fluid of Jinjiang cattle(P>0.05),while the molarity of propanoic acid was significantly increased(P<0.05),and had the tendency to increase the acetic acid/propionic acid ratio(0.05<P<0.1),but there was no significant difference.(2)Compared with the control group,the total number of OUTs in the two groups of Venn was similar,but the values of specific OTUs were different in the two groups.The effect of rare earth citrate on the a diversity index of rumen bacteria was not significant(P>0.05).On phylum level,The dominant flora in rumen fluid of the two groups was Bacteroidetes and Firmicutes,and the relative abundance of dominant bacteria groups was very close(P>0.05).Acidobacteria was the specific bacteria of experiment group(P<0.01).On genus level,rare earth citrate significantly increased the relative abundance of Bifidobacterium,and reduced the relative abundance of Brachymonas in tendency(0.05?P?0.1),but the difference was not significant.In summary:the rare earth citrate has a positive effect on the digestion of the starch and the degradation of the fiber in the rumen.Experiment 4:The aim of this study was to investigate the effects of rare earth citrate on slaughter performance,meat quality and fat metabolism of Jinjiang cattle.The material and design of experiment,slaughter of test animals were the same as experiment three,and recorded the relevant indicators according to the requirements.The results showed:(1)The addition of rare earth citrate in the diet significantly reduced the abdominal fat rate and fat percentage(P<0.05),and decreased the back-fat thickness and leaf fat rate(0.5?P?0.1)of Jinjiang cattle.(2)The addition of rare earth citrate in the diet significantly increased the content of crude protein in beef(P<0.05),reduced the content of crude fat and dry matter(P<0.05),and had the tendency to increase the shear force(0.5?P?0.1).(3)The addition of rare earth citrate in the diet significantly reduced the activity of MDA(P<0.05)and had the tendency to decreased the activity of FAS(0.05?P?0.1)in the liver.(4)The addition of rare earth citrate in the diet significantly increased the activity of LPL(P<0.05),and had the tendency to increase the level of TL(0.05?P?0.1)in the liver.To sum up,the addition of 400 mg/kg rare earth citrate in the diet could improve the slaughter performance,reduce the content of fat and improve the level of crude protein in muscle of Jinjiang cattle,and have a certain impact on its meat tenderness. |
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