| The study was conducted to investigate the effects of arginine on growth performance, immune action, carcass characteristics and blood lipid index of meat duck.According to single factor and completely randomised designs, 108 cherry valley meat duck of 3-day-old were assigned randomly to six dietary treatment group: groupâ… (as control),â…¡,â…¢,â…£,â…¤,â…¥, which was feeded basal diet added to 0, 0.125% 0.250%, 0.375%, 0.500%, 1.000% arginine. Semi-purified diet was as basal diet, and formulated to meet or exceed the nutrient requirements for ducks according to the NRC (1994) standards, but the content of arginine was 0.70% or 0.62%. Each group had three replicates of 6 ducks. The experiment lasted for 39 days. The feed consumption was recorded and body weight gain was measured for growth performance every week. At day 21, one duck per replicate was anatomized, and the left thymus, spleen and bursa of fabricius were collected to determine the immune organ index, then the samples of these immune organs were fixed in the 10% formalin liquid to manufacture paraffin section. The slices were observed under an olympus microscope. At day 42, one duck per replicate was taken blood samples from wing vein, separated serum and determined blood lipid index; Then, the ducks were slaughtered and anatomized for carcass traits, and the breast muscle, leg muscle, and liver was sampled for component analyze, the left thymus, spleen and bursa of fabricius was collected for immune organ index; Lastly, the abdominal fat in the same position was sampled and fixed in the 10% formalin liquid to produce the slices for histological observation.The results were showed as follows:(1) Adding arginine to basal diet promoted growth performance of ducks. Compared with control group, the ABW of groupâ…¡,â…¢,â…£,â…¤andâ…¥were increased by 24.02%, 24.20%, 25.08%, 29.03% and 27.04% (P<0.01) at the age of 42 day respectively; the ABW were increased by 24.98%, 25.17%, 26.06%, 30.21% and 28.17% (P<0.01) during d 3 to 42; the ADFI decreased by 13.45% (P>0.05), 16.65% (P<0.05), 25.58% (P<0.01), 18.81% (P<0.05) and 16.15% (P<0.05); the F/G decreased by 9.26% (P<0.05), 10.81% (P<0.01), 8.49% (P<0.05), 8.88% (P<0.05) and 9.26% (P<0.05).(2) Supplying arginine to the basal diet affected the immune-organs absolute weight and immune-organs index. Comparing with the control, at d 21, the absolute weight of Bursal, Thymus, Spleen of groupâ…¥were inereased by 54.85% (P<0.01), 36.17% (P<0.01) and 45.36% (P<0.05), respectively; at d 42, the Spleen of groupâ…¡,â…¢,â…£,â…¤andâ…¥were increased by 33.52%(P>0.05), 41.17%(P<0.05), 66.47%(P<0.01), 42.94% (P<0.05) and 45.29% (P<0.05), the Bursa of Fabricius were increased by 55.29% (P>0.05), 68.00% (P>0.05), 92.53% (P<0.05), 70.23% (P>0.05) and 88.74% (P<0.05), the Thymus were increased by 58.79%, 66.09%, 63.09%, 75.96% and 77.25% (P<0.01). But the difference among groupâ…¡,â…¢,â…£,â…¤andâ…¥was not significant (P>0.05).At d 21, additing arginine to the basal diet had the trend to increase the immune-organs index (P>0.05); At d 42, arginine did not affect the Bursa of Fabricius and Spleen index (P>0.05), but the Thymus index of groupâ…¥was increased by 48.73% compared with control group (P<0.05).According to the slices at d 21, arginine thickened obviously the cortex of thymus lobule; thickened obviously bursa fibrous and periarterial lymphatic sheaths of spleen, augmented spleen nodule and ellipsoid; developed well the police of bursas, retarded the degenerating of it.(3) After adding arginine to the basal diet, the slaughter rate and leg muscle percentage had the trend to improve (P>0.05). Comparing with the control, the eviscerate percentage of groupâ…¡,â…¢,â…£,â…¤andâ…¥were increased by 3.16% (P<0.05), 5.68% (P<0.01), 5.83% (P<0.01), 6.06% (P<0.01) and 7.24% (P<0.01) respectively; the half-eviscerate percentage were increased by 3.59% (P<0.05), 4.11% (P<0.05), 4.23% (P<0.05), 4.63% (P<0.05) and 6.17% (P<0.01).The dietary arginine did not affect the content of crude protein, ash and moisture in carcass, muscle and liver (P>0.05). But compared with control group, the content of crude fatty in breast muscle from groupâ…¡,â…¢,â…£,â…¤andâ…¥were increased by 55.83% (P<0.05), 57.05% (P<0.01), 49.69% (P<0.05), 33.13% (P<0.05) and 23.93% (P<0.05); inereased by 28.21% (P<0.05), 21.16% (P<0.05), 35.68% (P<0.01), 26.56% (P<0.05) and 31.54% (P<0.01) in leg muscle; and increased significantly in liver (P<0.01) .(4) Comparing with the control group at the end of this experiment, the blood total cholesterol of groupâ…¡,â…¢,â…£,â…¤andâ…¥were decreased by 9.75% (P>0.05), 16.88% (P>0.05), 31.70% (P<0.05), 38.83% (P<0.05) and 35.08% (P<0.05) respectively; the blood high density lipoprotein were decreased by 10.29% (P>0.05), 9.92% (P>0.05), 16.17% (P>0.05), 29.04% (P<0.01) and 22.05% (P<0.05); the low density lipoprotein were decreased by 22.41% (P<0.05), 25.00% (P<0.05), 26.72% (P<0.05), 27.58% (P<0.05) and 28.44% (P<0.05). The difference among groupâ…¡,â…¢,â…£,â…¤andâ…¥was not significant (P>0.05).(5) The dietary arginine affected obviously the development of fat cell and fatty deposition. Compared with control group, the fat cell diameter of groupâ…¡,â…¢,â…£,â…¤andâ…¥were decreased by 10.91%, 14.57%, 18.92%, 19.28% and 23.49% (P<0.01); the fat cell volume were decreased by 28.96%, 36.59%, 45.00%, 47.36% and 53.89% (P<0.01); the fat cell number g-1 tissue were increased by 39.96%, 56.40%, 80.27%, 87.89% and 115.05% (P<0.01).With the the increasing of dietary arginine, sebum contents and hepatic adipose contents were decreased significantly (P<0.05), abdominal adipose content had the same trends (P>0.05).In conclusion: the growth performance of the diets with 1.120% arginine was optimized; the immune action was the best in diet with 1.620% arginine; adding arginine to basal diet decreased significantly adipose contents of carcass and blood lipid, the reducing adipose contents of ducks probable be attributed that arginine can inhibite fat cells from enlarging and reduce fat to deposit in fat cells.
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