| Experiment 1:Effects of dietary vitamin D3 levels on boar reproductionThis study was conducted to evaluate the effects of dietary vitamin D3 supplementation on reproductive performance of boars.Twenty-four Yorkshire boars with eighteen months were randomly allocated to one of three dietary treatments composed of total vitamin D3 levels of 200 IU/kg(C),2000 IU/kg(T1)and 4000 IU/kg(T2).Each group had 8 repeat of one boar.The trial lasted for 112 days.Semen was collected with 2 times a week to determine the sperm quality.Blood was collected for d 1,56 and 112.Seminal plasma and sperm were collected for d 56 and 112.The concentration of testosterone(T),estradiol(E2),calcium(Ca2+),phosphorus(P)and aromatase activity in blood plasma were measured.The concentration of fructose,Ca2+.P and acid phosphatase(ACP)activity in seminal plasma were measured.The results showed as follows:1 Supplementation of vitamin D3 in diets had no significant influence for the feed intake,testis volume,libido,semen volume and sperm concentration among each group(P>0.05).Sperm motility,effective sperm number per ejaculate,acrosome intactness ratio and membrane intactness ratio in Tl group boar were significantly higher than those in C group in the 1-8 weeks(P<0.05),however,sperm motility and membrane intactness ratio in T2 group boar had no significant difference when compared with other groups(P>0.05).Sperm motility,effective sperm number per ejaculate,acrosome intactness ratio and normal sperm percentage in T1 group were significantly higher than those in C and T2 groups in the 9-16 weeks(P<0.05).Sperm membrane intactness ratio and sperm curve velocity in T1 group were significantly higher than C group.However,sperm membrane intactness ratio and sperm curve velocity in T2 group had no significant difference compared with C group(P>0.05).Sperm membrane intactness ratio and normal sperm percentage in T1 group were significantly higher than those in C and T2 groups during the 1-16 weeks(P<0.05).Sperm motility,effective sperm number per ejaculate,acrosome intactness ratio and progressive velocity in T1 group boar were significantly higher than C group(P<0.05).2 Supplementation of vitamin D3 in diets significantly increased the concentrations of 25-OHD3 in blood at d 56 and 112(P<0.05).Seminal plasma 25-OHD3 concentrations in T1 group were significantly higher than C group at 112(P<0.05),while seminal plasma 25-OHD3 in T2 group had no significant difference compared with other groups(P>0.05).3、Dietary treatment did not affect blood P concentrations of boars(P>0.05).Blood Ca2+,testosterone,estradiol concentration and aromatase activity in T1 group were significantly higher than C group(P<0.05),while T2 group had no significant difference compared with other groups(P>0.05).4、Compared with C group,seminal plasma Ca2+,fructose conceUtration and ACP activity in T1 group were significantly higher(P<0.05).while T2 group had no significant difference compared with other groups(P>0.05).5、Compared with C group,sperm mRNA abundances of CYP19,CYP24A1 and VDR in T1 and T2 groups were significantly higher(P<0.05).However,sperm mRNA abundances of CYP27B1 had no significant difference among groups(P>0.05).In summary,in the conditions of this study,supplementation of vitamin D3 in diet with 2000 IU/kg can increased blood 25-OHD3 concentration,increased the expression levels of CYP19,CYP24A1 and VDR,promoted the secretion of testosterone and estradiol secretion,and increased the concentration of seminal plasma Ca2+,fructose and ACP activity,and therefore improved semen quality.Experiment 2:Effects of dietary vitamin D forms on boar reproductionThe current study was to investigate the effects of dietary-vitamin D supplementation forms on reproductive performance of boars.Sixteen Yorkshire boars with eighteen months were randomly allocated to one of two groups(VD3 group,the diets contained 50 μg/kg vitamin D3,and 25-OHD3 group,the diets contained 50 μg/kg 25-OHD3),and each group had 8 repeat of one boar.The trial lasted for 16 weeks.Semen was collected with 2 times a week to the determination of normal semen quality.Blood was collected for d 1,56 and 112.Seminal plasma and sperm were collected for d 56 and 112.The concentration of T.E2,Ca2+,P.and aromatase activity in blood plasma were measured.The concentration of fructose,Ca2+,P and ACP activity in seminal plasma were measured.Results showed as follows:1、Compared with VD3 group,supplementation of 25-OHD3 in diets had no significant effect on semen quality within 1-8 weeks(P>0.05).In the 9-16 weeks,sperm motility,effective sperm number per ejaculate,acrosome intactness ratio,normal sperm percentage and progressive velocity in 25-OHD3 boars were significantly higher than VD3 group(P<0.05).In the 1-16 weeks,sperm motility,effective sperm number per ejaculate and normal sperm percentage in 25-OHD3 group boar were significantly higher than VD3 group(P<0.05).2、Supplementation of 25-OHD3 in diets significantly increased blood Ca2+,estradiol concentration and aromatase activity(P<0.05),and increased seminal plasma 25-OHD3,Ca2+,fructose concentration and ACP activity(P<0.05).However,the forms of vitamin D supplement in diets had no significant influence on the blood P concentrations of boars(P>0.05).3、Supplementation of 25-OHD3 in diets of boars significantly increased the expression levels of CYP19,CYP24A1 and VDR(P<0.05).However,the forms of vitamin D supplement in diets had no significant influence on the expression levels of CYP2R1 and CYP27B1(P>0.05).In summary,supplementation of 25-OHD3 in diet is conducive to sex hormone.fructose secretion and promoting the expression levels of CYP19,CYP24A1 and VDR,increased ACP and aromatase activity,and then improved sperm morphology and athletic ability.These studies indicated,supplementation of vitamin D3 in diet with 2000 IU/kg can improve boar vitamin D status,increase the gene expression of CYP19,CYP24A1 and VDR,promote reproductive hormone secretion and improve the seminal plasma environment,and then improve semen quality.Compared with VD3 group,supplementation of 25-OHD3 in diets can improve effective boar vitamin D status,and then improve sperm morphology and athletic ability. |
