| Four experiments were respectively conducted to evaluate growth performance and breeding model for transgenic human lactoferrin holstein calves, moreover investigate the rule of growth and feeding and management standard between hLF calves and ordinary Holstein calves under the same feeding and management conditions. Verifying the effect of perfect forage diet on growth performance for weaned calf, meanwhile evaluating the effect of heat stress on the growth performance and metabolism for hLF calves.Experiment1, At0～6months age,30hLF Holstein calves and30ordinary Holstein calves (5calves every month) were allocated to same treatment.to study the differences in growth performance and blood biochemical index between hLF Holstein calves and ordinary Holstein calves. The result shows that there were no significantly differences in body weight and body measurement between the two kinds of calves (P>0.05). There were no significantly differences in TP, ALB, T3, T4, Glu and GH(P>0.05), but GLB of hLF calves tended to higher than ordinary Holstein calves (P=0.07). A/G and IgG appeared an opposite tendency (P=0.07and P=0.08). These changed tendency need further determination.Experiment2, At5-6months age,48hLF Holstein calves were randomly divided into3groups, and every group has16calves. According to the Chinese feeding standard of dairy cattle (2004), formulate ration to meet the nutrient need for different ADG (300g/d,600g/d and900g/d). The result shows that ADG of calves feeding the daily weight gain diet of300g/d,600g/d and900g/d were317g/d,616g/d and922.4g/d. This indicated that nutrient standard of hLF transgenic calf dietary can reference Chinese feeding standard for dairy cattle (2004). With the increase of ADG, GLU and BUN concentration were significantly increased (P<0.05). while T3, IGF-1concentrations were significantly decreased (P<0.05), IgG. ACTH tended to increased (P<0.10), while T4, LEP tended to decreased (P<0.10). With the increase of ADG, the apparent digestion rate of CP, NDF and ADF in diet increased significantly (P<0.05).Experiment3, At5-6months age,30transgenic human lactoferrin of Holstein calves were chosen and divided into two groups (15/group) which have similar growth performance and birth date. The control group, feedhigh crude protein (21.91%DM) concentrate, Chinese wildrye was offered ad libtum daily.. The treatment group, fed with concentrate with low crude protein (14.07%DM), alfalfa was offered ad libtum daily. The results indicated that the average daily gain of calves in treatment group tended to increase (P=0.085). and serum GLB, GLU, BHBA and BUN concentrations in treatment group were increased significantly than control group (P<0.05), in addition, concentration of TP in treatment group tended to increase (P=0.085). Whereas IgG、GH、IGF-1and Cor concentrations were decreased significantly (P<0.05).Experiment4. At3-5months age,15transgenic human lactoferrin of Holstein calves (5/month age) were separately chosen to study the effect of heat stress in Summer and autumn. All the calves were given same feed and management. The result indicated that heat stress significantly decreased the average daily gain of calves (P<0.05). and increased rectal temperature (RT), respiration rates (RR) and serum PH (P0.01). The concentrations of Glu、Na+、Cl-、T3、GH were significantly lower (P<0.05).The results showed that:there were no significantly differences in growth performance for hLF transgenic calves and ordinary Holstein calves (P>0.05). hLF transgenic calves diet formulation can refer to Chinese feeding standard for dairy cattle (2004) and use ordinary Holstein calf management. Supplemention of alfalfa hay to low protein diet concentrate promotes the growth of hLF calf. Heat stress influences the physiological state of hLF calf, and significantly inhibit its growth. |
PDF Full Text Request