| The nutritional physiological functions of lactoferrin on the segregated early weaning Landrace Meishan F1 piglets were studied systemically. The studies confirmed SEW could improve piglets growth performance significantly (10-15%). In traditional weaning conditions, 60 d bodyweight of Landrace X Meishan F1 piglets was in the range of 14-15kg. In SEW condition, 60 d bodyweight could reach 16.5-17.5kg. Meanwhile, SEW piglet's growth performance could be further improved by supplementing 230 mg/kg LF (12-20%). 60 d bodyweight of piglets could reach 18.5-19.5kg by LF in SEW. The mechanisms of LF's growth promoting roles in SEW piglets were studied systemically.The different dietary levels of lactoferrin on the growth performance and iron metabolism related indexes (including hemoglobulin.total iron binding capacity.serum iron) as well as cytokines (IL-1 a , ll.-l g , IL-6 and TNF a ) of SEW piglets were studied. The antimicrobial abilities of LF and LFc were determined by minimum inhibitory concentration (MIC value) and compared with traditional antibiotics. The antimicrobial molecular biological mechanisms of LFc on E.Coli. and Salmonella were tentatively studied. The effects of LF and SEW on the whole body protein turnover coefficients of piglets were studied through isotope trace techniques. The results of studies confirmed that SEW could improve the growth performance of piglets and discovered that the growth performance of SEW piglets could be improved further by adding 230 mg/kg LF in diets. The studies could supply theoretic bases for the efficient construction of SEW and gave the direct experimental evidences for the usage of SEW in China. Six systemical trials were done.Trial 1. 48 piglets (Landrace Meishan),weaned at 14?d ,were used to test the effects of different dietary levels of lactoferrin (0,30,100,300,500,1000 mg/kg) on the growth performance. Non-complete 2 factors experimental design was adopted. The antibiotics control group and low nutritional levies (the nutritional level was 90% of the normal groups) supplemented with 300 mgLF/kg. In segregated conditioned piglets houses, the piglets were divided into 9 groups, every group had 6 piglets, every group had 3 replicates, and 2 piglets per replicate. Based on the postweaning 2 weeks piglets bodyweight, regression equations were constructed (R2=0.9787). The maximun piglet bodyweight could be gotten at the 270.58 mg/kg lactoferrin levels. Piglets of 300 and 1000 mgLF/kg groups had no significant diffrence with the antibiotics control group.Trial 2. Based on the results of trial 1, the single factor experimental design was adopted. The effects of dietary lactoferrin levels on the growth performance, nutrient digestbilities,blood iron metabolism indexes and cytokines were tested. 60 piglets, weaned at 14眑d, were alloted into different treatments. Every treatment had 3 replicates and there were 4piglets per replicate. The dietary nutritional levels were divided into 3 stages (14-28d,29-42d, 43-60d). In segregated conditioned piglets house, piglets were alloted into different treatments randomly. The blood samples were gotten at the end of trial. The results showed the maximum growth performance of piglets was arrived at 233.78 mgLF/kg. The regression equation was y = -0. 0016x + 0. 7481x + 266.45,R2 = 0.9949;x=233.78mg/kg, ymax=354.06,PO.01.The diarroa indexes were decreased very significantly in 200 and 400 mgLF/kg groups.As the LF content increased, digestbilities of nutrients increased and reached the maximum value at 200 mgLF/kg group. The SI,TIBC and Hb increased with the increasing levels of lactoferrin.The cytokines at LF treatments groups were significantly lower than the control group (P0.05). The cytokines of 100,200 and 400mg LF/kg groups were very sinificantly lower than the control group (P<0.01). The cytokine levels and ADG of SEW piglets had significant negative corelation. LF stimulated the growth performance through lowering the cytokine level and improving iron metabolism.Trial 3 60 piglets (LandraceX Meishan) ,weaned at 14+...
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