Study On Main Minerals Distribution And Requirement Parameters Of Yak Calves At Late Growth Stage

This paper takes the yak calf as the research object.,and the apparent digestibility of nutrients,blood biochemical indexes and slaughter performance of yak calves at different weight stages in the later growth stage were obtained by comprehensively adopting the methods of feeding experiment,digestion experiment and comparative slaughter experiment.The content of mineral elements calcium,phosphorus,sodium,potassium,magnesium,copper,iron,zinc and manganese in various tissues of yak calves and their distribution in the body were studied,and the factorial method was used to establish the yak calves.The growth requirement model was used to obtain the nutrient requirement parameters of main mineral elements in the late growth stage of yak calves,which supplemented the basic data of yak feeding standards,and provided an important reference for the nutritional regulation of yak calves in the late growth stage.The research contents of the thesis are as follows:Part 1:Study on the apparent digestibility of nutrients,blood biochemical indexes and slaughter performance of yak calves at different weight stages in the late growth stageThe purpose of this experiment was to systematically study the apparent digestibility of nutrients,blood biochemical indexes and growth performance of yak calves at different weight stages.Twenty-one healthy yak calves with similar body weight（60.44±4.59kg）were selected and randomly divided into 3 groups after a15-day pre-test,with 7 calves in each group,BL group,M group and F group respectively.Feeding,the trial period is 60d.The three groups of yak calves were subjected to digestion tests,and the total manure method was used to determine the content of nutrients and minerals in the diet and manure to obtain the apparent digestibility of nutrients in different growth weights of yak calves.Serum samples were collected,and blood biochemical indicators were determined.The test calves were slaughtered at average body weights of 73.61 kg,81.96 kg and 96.53 kg,respectively.Each tissue sample was weighed and the data were recorded to analyze the growth performance and slaughter performance of the calves in each group.The results showed that:1)DMI increased significantly with the increase of body weight（P<0.05）;the apparent digestibility of Ca,P and DM decreased significantly with the increase of body weight（P<0.05）;the apparent digestibility of CP in BL group was significantly higher than that in M??group and DM group.Group F（P<0.05）;NDF in group F were significantly higher than those in group BL and group M（P<0.05）.2)The contents of ALB,GLB,AST,ALT,GLU and TG in the serum of group F were significantly higher than those of group BL and group M（P<0.05）.TP increased with the increase of BW（0.05≤P<0.1）.It showed a downward trend with the increase of BW（0.05≤P<0.1）.3)With the increasing body weight of yak calves,the meat weight,viscera（including blood）weight,tare weight and gross weight all increased significantly（P<0.05）.The bone weight and fat weight of the F group were significantly higher than those of the other two groups（P<0.05）,and the bone growth rate slowed down,while the muscle growth rate showed an increasing trend.Part 2:Study on the distribution law and growth requirements of macromineral elements in yak calves in the late growth stageThe purpose of this experiment was to obtain the distribution law and growth requirement model of macromineral elements calcium,phosphorus,sodium,potassium and magnesium in the late growth stage of yak calves.The experimental animals and groups were the same as in the first experiment.The contents of mineral elements calcium,phosphorus,sodium,potassium and magnesium in the tissues of the three groups of test cattle were determined,the distribution law of macromineral elements in vivo was analyzed,and the growth requirement model was established.The results showed that:1)Bone is the main deposition site of elements calcium,phosphorus,sodium and magnesium;potassium is mainly distributed in muscles,and the proportion of bones and internal organs is also higher;macromineral elements are less in fat;The water content in the body of yak calves showed a decreasing trend with the increase of age.2)The prediction model and requirements of macromineral elements in the late growth stage of yak calves are:the prediction model of calcium NRG_Ca=21.5207×EBW^-0.0885,the net requirement is NRG_Ca=14.91-15.21 g/kg EBW;the prediction model of phosphorus NRG_P=11.3862×EBW^-0.0779,the net requirement is NRG_P=8.24-8.39 g/kg EBW;the sodium prediction model NRG_Na=1.0125×EBW^-0.0807,the net requirement is NRG_Na=0.73-0.74 g/kg EBW;Potassium prediction model NRG_K=0.8810×EBW^0.2650,the net requirement is NRG_K=2.49-2.65 g/kg EBW;The prediction model of magnesium is NRG_Mg=0.04567×EBW^0.5209,and the net requirement is NRG_Mg=0.35-0.40 g/kg EBW.Part 3:Study on the distribution law of trace mineral elements and growth requirements of yak calves in the late growth stageThe purpose of this experiment was to obtain the distribution law and growth requirement model of trace minerals copper,iron,zinc and manganese in the late growth stage of yak calves.The experimental animals and groups were the same as in the first experiment.The contents of mineral elements copper,iron,zinc and manganese in the tissues and organs of the three groups of test calves were measured,the distribution law of trace mineral elements in vivo was analyzed,and a growth requirement model was established.The results showed:1)The proportion of copper and iron in the viscera was the highest in the body,the content of zinc in the muscle was the largest,the deposition of manganese in the viscera was the largest,and the content of trace minerals in the fat was less.2)The prediction model and requirements of trace mineral elements in the late growth stage of yak calves are:the prediction model of copper is NRG_Cu=4.4025×EBW^-0.1228,the net requirement is NRG_Cu=2.65-2.72 mg/kg EBW;the prediction model of iron NRG_Fe=94.4258×EBW^0.0039,the net requirement is NRG_Fe=95.88-95.97mg/kg EBW;the zinc prediction model NRG_Zn=5.1939×EBW^0.4161,the net requirement is NRG_Zn=26.55-29.19mg/kgEBW;manganeseforecastModel NRG_Mn=1.5044×EBW^0.2273,the net requirement is NRG_Mn=3.67-3.86 mg/kg EBW.