| The study included two experiments to investigate the effect of dietary vitamin levels on growth performance,breast meat quality in meat ducks,and verify the applicability of suitable vitamin levels by dietary rapeseed meal.Experiment 1 Effect of different dietary vitamin levels on growth performance and breast meat quality of meat duckIn total,1008 one-d-old ducklings were fed with diets containing seven levels of complex vitamin,dietary vitamin levels were the lowest for T1（VA 1925 U/kg;VD3 308 U/kg;VE 7.7mg/kg;VK3 0.385 mg/kg;VB2 3.08 Mg/kg;VB6 1.925/kg mg;pantothenic acid 8.47 mg/kg;Niacin 42.35 mg/kg）,the highest for T7(VA 16500 U/kg;VD3 5500 U/kg;VE 88 mg/kg;VK35.5 mg/kg;VB1 3.3 mg/kg;VB2 7.7 mg/kg;VB6 7.7 mg/kg;VB12 0.044 mg/kg;pantothenic acid 16.5 Mg/kg;nicotinic acid 42.35 mg/kg;folic acid 2.2 mg/kg;biotin 0.275 mg/kg;VC 110mg/kg),and the other five dietary treatments are mixed according to different ratios between T1and T7.Each dietary treatment consisted of 8 replicate cages of 18 birds.The results showed that,body weight（BW,14 d）,body weight gain（BWG,d1-14）and feed to gain ratio（F/G,d1-14,d15-35 and d1-35）increased（P<0.05）in a linear manner with increasing of dietary vitamin levels,but F/G（d 36-49）linearly decreased（P<0.05）.Meanwhile,the MDA in breast meat at35 d and 49 d decreased（P<0.05）in a linear manner with increasing of dietary vitamin levels.These results suggested that different levels of vitamin requirement in different production stages of meat duck,the vitamin level required for 1-35 d is higher than 36-49 d.The vitamin requirement of meat ducks during 1-35 d is recommended for T6,and during 36-49 d is recommended for T2.Experiment 2 Re-evaluation of the dietary opitmal vitamin level for meat duckThis study was conducted to evaluate whether vitamin premix could alleviate the deleterious effect of rapeseed meal（RSM）inclusion in diets of meat ducks based on performance,antioxidative capacity,liver and thyroid histopathology.A total of 674 15-d-old ducks were randomly allocated to 6 treatments with 7 cages of 16 ducks on the basis of body weight（BW）.Six isonitrogenous and isocaloric experimental diets were used under a 2×3factorial arrangement with 2 kinds of vitamin premixes(High and Low;Low premix had lower levels of all vitamins,and deficiency of VB1,VB12,folic acid,biotin,and VC than the High premix),and 3 levels of RSM（5%,10%and 20%,the RSM containing 466 mg/kg isothiocyanates and 590mg/kg oxazolidinethione on analyzed basis）.There were significant（P<0.05）dietary RSM levels by Vitamin premixes interactions on BW（d 35）,BW gain（BWG）,feed to gain ratio（F/G）and serum SOD activities.When ducks fed High vitamin premix diets,there was a significantly（P<0.05）increase on BW（d 35）,BWG and decrease on F/G of ducks fed diets containing 5%and 10%RSM,while had no effect（P>0.05）on performance when ducks fed a diet containing 20%RSM.However,High vitamin premix significantly（P<0.05）increased on serum superoxide dismutase activity of ducks fed diets containing 10%and 20%RSM and decreased the total scores of liver and thyroid histopathology.These results suggested that High vitamin premix could eliminate the negative effect induced by 5%or 10%RSM in ducks by improving antioxidative capacities and alleviating the liver and thyroid damage.However,High vitamin premix could not extinguish the deleterious effect induced by 20%RSM. |
