Effects Of Dietary 25（OH）D₃ And Calcium Levels On Performance And Skeletal Quality Of Ducks Infected With Novel Goose Parvovirus

In this paper,two experiments were conducted to investigate the effects of injection of the Novel goose parvovirus（NGPV）JS1 strain on the performance and bone quality of meat ducks and the effects of dietary 25（OH）D₃ and calcium levels on the performance and bone quality of ducks infected with NGPV.It provides a theoretical basis for further understanding the effect of NGPV on the bone quality of meat ducks,and provides data support for the use of nutritional methods to alleviate short beak dwarf syndrome in production.Experiment 1:Effects of dietary supplementation with 25（OH）D₃ on performance and bone quality of ducks infected with NGPVThis experiment explored the effect of NGPV on the performance and bone quality of meat ducks and the effect of dietary supplementation with 25（OH）D₃ on the performance and bone quality of infected NGPV meat ducks.The experiment adopts a 2×2 factor design,setting 4 treatments,setting NGPV challenge and non-attack,the challenge duck is injected with NGPV-JS1 strain 0.5 m L（5×10⁷copies/m L）at the age of 1 day,and two 25（OH）D₃addition level（0 or 69μg/kg）,8 repeats per treatment,4 meat ducks per repeat.The test is conducted for 35 days.The results showed that NGPV significantly reduced the body weight of 14-and35-day-old meat ducks,body weight gain and feed intake at various stages（P<0.001）,and significantly increased the feed-to-weight ratio during the whole period（P<0.05）.Adding25（OH）D₃ to the diet had no significant effect on the body weight,body weight gain,feed intake and feed-weight ratio of meat ducks（P>0.05）.NGPV significantly reduced the beak length and beak width of meat ducks at 7,14,21,28 and 35 days of age（P<0.05）.Adding25（OH）D₃ to the diet had no significant effect on beak length and beak width of meat ducks（P>0.05）.NGPV significantly reduced the tibia length,diameter and ash content of35-day-old meat ducks（P<0.05）,but had no significant effect on the calcium and phosphorus content of ash（P>0.05）.The addition of 25（OH）D₃ significantly increased the phosphorus content in the tibia length and ash content of 35-day-old ducks infected with NGPV（P<0.05）.NGPV significantly increased the expression of Cathepsin K gene in the tibia of 35-day-old ducks（P<0.05）,and the addition of 25（OH）D₃ significantly increased the expression of V-ATPase gene in ducks infected with NGPV（P<0.05）.Decreased the expression of TRPV6and Ca BP-28K genes in 35-day-old meat duck kidneys（P<0.05）,and the addition of25（OH）D₃ significantly increased the expression of TRPV6,Ca BP-28K,and Na Pi-IIa genes in kidneys（P<0.05）,but the effect was not significant in ducks infected with NGPV（P>0.05）.The results showed that NGPV reduced the growth performance and tibia quality of meat ducks.The addition of 25（OH）D3 in the diet had no significant effect on the performance of meat ducks,but it increased the length of the tibia of ducks infected with NGPV,improve tibia phosphorus content,improve tibia quality.Experiment 2:Effect of dietary calcium level on performance and bone quality of ducks infected with NGPVThis experiment explored the effects of dietary calcium levels on the performance and bone quality of ducks infected with NGPV.The experiment adopts a 3×2 factor test design,setting three calcium levels（1-14 days old:0.65%,0.90%,1.15%;14-35 days old:0.60%,0.85%,1.10%）,setting NGPV attack With no challenge,the challenged ducks were injected with 0.5 m L(5×10^9.66 copies/m L)of NGPV-JS1 strain at 1 day of age,a total of 6 treatments,8 replicates per treatment,and 8 ducks per replicate.The test is conducted for 35 days.The results showed that:NGPV significantly reduced the body weight of meat ducks at14 days and 35 days,body weight gain and feed intake at all stages（P<0.05）,and significantly increased the feed-weight ratio at 1-14 days（P<0.05）.Dietary calcium level had no significant effect on production performance（P>0.05）.NGPV significantly reduced the beak length and beak width of 14-day and 35-day-old meat ducks（P<0.05）,and increasing the calcium level significantly increased the relative beak length of 35-day-old（P<0.05）.NGPV significantly reduced the fresh weight,tibia length,tibia diameter,tibia strength,and fresh beak weight of meat ducks（P<0.05）.Increasing calcium levels significantly increased the diameter and strength of the 14-day-old tibia（P<0.05）,significantly increased the length of the tibia and fresh beak weight of the 14-day-old infected NGPV meat duck（P<0.05）,and significantly increased the 35-day-old infected NGPV meat duck Tibia length（P<0.05）.NGPV significantly reduced the tibial defatted weight,tibia ash,and beak defatted weight of14-and 35-day-old meat ducks（P<0.05）,and increased dietary calcium levels significantly increased the tibial ash content and beak defatted weight of 14-day-old meat ducks（P<0.05）,significantly increasing the tibia ash content of 35-day-old meat ducks（P<0.05）,significantly increasing the defatted weight of 35-day-old ducks infected with NGPV（P<0.05）.NGPV significantly increased the number of osteoclasts in 14-and 35-day-old ducks（P<0.05）,and increasing calcium levels significantly reduced the number of osteoclasts in 35-day-old ducks（P<0.05）.Increasing calcium level significantly reduced serum TRAP content at 35 days（P<0.05）.NGPV has a tendency to reduce the expression of Ca BP-28K in the duodenum of14-day-old meat ducks（P<0.1）,and the increase of calcium level significantly reduces the expression of Ca BP-28K and Na Pi-IIb in the duodenum of 14-day-old meat ducks（P<0.05）,NGPV significantly reduced the expression of Ca BP-28K and Na Pi-IIb in the duodenum of35-day-old meat ducks（P<0.05）.NGPV significantly increased the expression of Cathepsin K gene in 14-and 35-day-old ducks（P<0.05）,and had a tendency to decrease the expression of ALP and Runx2 in 35-day-old ducks（P<0.1）.The results show that NGPV significantly reduces the performance of meat ducks and reduces bone quality;increasing calcium levels has no significant effect on the performance of meat ducks,but significantly increases the tibia length and ash content of infected NGPV meat ducks and improves tibia quality.Conclusion:NGPV reduces the performance of meat ducks,affects the development of the duck’s beak and tibia,and reduces the quality of the tibia.Dietary 25（OH）D₃ and calcium levels had no significant effect on the performance of ducks infected with NGPV.The addition of 25（OH）D₃ to the diet significantly increases the length of the tibia of infected NGPV meat ducks,increases the phosphorus content of the tibia,and improves the quality of the tibia.Increasing the calcium level can increase the tibia length and ash content of NGPV infected ducks,and improve the tibia quality.The appropriate calcium levels for meat ducks infected with NGPV are:1-14 d 1.15%,15-35 d 1.10%.