Effects Of Dietary Vitamin D Combinations On Growth Performance,Body Shape,and Bone Development In Meat Ducks During Grower Or Feeding Restricted Period

This thesis was conducted to investigate the effects of dietary supplemented of several combinations of vitamin D₃（VD₃）and 25-hydroxycholecalciferol（25-OH-D₃）on the growth performance,body shape development,and the development and calcification patterns of tibia and sternum in meat ducks during the 1-32 day growth period and the 33-52 day restricted feeding period by two experiments.The aim is to recommend a suitable VD combination for meat ducks and to provide some theoretical and technical support for high-quality production of meat ducks.Experiment 1.Effects of different combinations of VD₃ and 25-OH-D₃ on growth performance,body shape development,bone calcification and metabolism in meat ducks during growing and feeding restriction period.During growth stage（1-32 d）,two dietary treatments were set up:VD₃ 3,160 IU/kg and VD₃ 400IU/kg+25-OH-D₃ 69μg/kg,with free intake of feed and water.During restricted feeding stage（33-52 d）,a 2×5 factor design was adopted.The two dietary treatments during growth stage were fed separately 5 different VD combination diets during restricted feed stage,as follows:VD₃ 2,000 IU/kg;VD₃ 5,000 IU/kg;VD₃3,620 IU/kg+25-OH-D₃ 34.5μg/kg;VD₃ 2,240 IU/kg+25-OH-D₃ 69μg/kg;VD₃1,800 IU/kg+25-OH-D₃ 80μg/kg,with 250 g diet per duck every 2 days.The results showed that:（1）During the growth stage,dietary supplemented with VD₃ 400 IU/kg+25-OH-D₃69μg/kg at 1-32 days decreased the ratio of feed to gain（P<0.1）and the flipper index（P<0.05）;however,it significantly improved the wing weight,body tilt length,and sternal calcium content（P<0.05）,as well as up-regulated the m RNA expression of VDR in duodenal mucosa and Na Pi-IIb in kidney of meat ducks at 32d of age（P<0.05）.（2）During the feeding restriction stage,regardless of dietary VD combinations in this stage,VD₃ 400 IU/kg+25-OH-D₃ 69μg/kg during the growth stage significantly increased（P<0.05）the body weight,body oblique length,hip width,sternum depth,breast muscle weight,breast muscle yield,half-eviscerated weight,eviscerated weight,sternum defatted weight and ash content（P<0.1）,and the gene expression of bone formation specific gene DMP1 and markedly decreased（P<0.05）the flipper weight,flipper rate,tibia length,tibia ash and phosphorus content of of meat ducks at 52 d of age.（3）Regardless of dietary VD combinations during the growth stage,diets with VD₃ 1,800 IU/kg+25-OH-D₃ 80μg/kg tended to increase（P<0.1）the half-eviscerated weight and eviscerated weight and significantly up-regulated（P<0.05）the m RNA expression of ALP in sternum,Na Pi-IIa and Na Pi-IIb in duodenum and kidney,Ca BP-28K in duodenum,and VDR in kidney of meat ducks at 52 d of age.In addition,VD₃ 400IU/kg+25-OH-D₃ 69μg/kg during the growth stage combination with VD₃ 1,800 IU/kg+25-OH-D₃ 80μg/kg or combination with VD₃ 3,620 IU/kg+25-OH-D₃ 34.5μg/kg during the feeding restriction stage significantly increased（P<0.05）the body weight of meat ducks at 52d and presented a significant interactive effect on the body weight gain（P=0.052）.Experiment 2.Effects of different combinations of VD₃ and 25-OH-D₃ during growth and feeding restriction periods on bone growth and calcification patterns of 33-52d feeding restricted ducksIn order to further determine the effects of the combined dosage of VD₃ and25-OH-D₃ on the body shape,tibia and sternum development and calcification of meat ducks during the feeding restricted period,two dietary treatments were set up during the growth stage（1-32 d）:VD₃ 3 160 IU/kg and VD₃400 IU/kg+25-OH-D₃69μg/kg,respectively,and during restricted feeding stage（33-52 d）3 different VD combination diets were as follows:VD₃ 2,000 IU/kg;VD₃ 5,000 IU/kg;VD₃ 1,800IU/kg+25-OH-D3 80μg/kg.Samples were collected at 32 d,36 d,40 d,44 d,48 d and 52 d of age,respectively.The feeding mode and experimental dietary nutrition levels during the two stages were consistent with these in the experiment 1.The results showed that:（1）There was a significant interactive effects among VD combinations during the growth stage,VD combinations during the feeding restrict stage,and day age on the body weight,breast muscle weight,breast muscle yield,sternum depth,and the content of ash,calcium,and phosphorus in sternum of ducks during 33-52 d restricted period（P<0.05）.When VD₃ 400 IU/kg+25-OH-D₃ 69μg/kg during the growth stage combination with VD₃ 1,800 IU/kg+25-OH-D₃ 80μg/kg during the feeding restriction stage,the body weight at 52 days was the highest and the breast muscle weight,breast muscle yield,sternum depth,and the content of calcium and phosphorus in sternum reached a high level at 48 days of age.When VD₃ 400 IU/kg+25-OH-D₃ 69μg/kg during the growth stage combination with VD₃ 5,000 IU/kg during the feeding restriction stage,the mineral content in sternum was the highest at52 days.（2）During the feeding restriction period,the body shape,slaughter performance,the calcification of tibia and sternum of restricted ducks were significantly affected by the day age（P<0.05）.Body shape（semi-submersible length,tibial length and circumference）,slaughter performance（live body weight,breast muscle yield,wing yield,and fresh sternal yield）,tibial defatted weight,tibial phosphorus content,sternum morphological parameters and mineral content significantly increased with the increase of day age（P<0.001）;however,the yield of flippers and fresh tibia as well as the content of tibial ash and calcium first increased,and then decreased during feeding restriction stage（P<0.05）.（3）Compared with VD₃ 3160 IU/kg in 1-32 d diet,adding VD₃ 400 IU/kg+25-OH-D₃ 69μg/kg in 1-32 d diet significantly increased（P<0.05）the live body weight,body tilt length,breast muscle weight,sternum weight,sternum depth,sternum defatted weight,sternum and tibia ash and calcium and phosphorus contents of ducks at 52d of age.VD₃ 400IU/kg+25-OH-D₃ 69μg/kg during the growth stage combination with VD₃ 1,800 IU/kg+25-OH-D₃ 80μg/kg during the feeding restriction stage significantly increased（P<0.05）the sternum strength and the sternal calcification reached a high level at 48d of age.In conclusion,diet supplemented with VD₃ 400 IU/kg+25-OH-D₃ 69μg/kg during the growth stage combination with VD₃ 1800 IU/kg+25-OH-D₃ 80μg/kg during the feeding restriction stage could improve the growth performance,body shape development,slaughter performance,and the development and calcification of sternum via regulating the genes expression of bone turnover,intestinal calcium absorption as well as calcium and phosphorus re-absorption in kidney.Based on the quality of sternal calcification,we recommended the VD combination project was as follows:VD₃ 400 IU/kg+25-OH-D₃ 69μg/kg VD₃ during the growth stage（1-32d）combination with VD₃ 1800 IU/kg+25-OH-D₃ 80μg/kg during the feeding restriction stage（33-52d）.