Repeated injections of vitamin E and Se improves testicular morphology, testosterone and in vitro and in vivo sperm fertility in subfertile rabbits

Abstract

Subfertility is a multifactorial disorder that affects the rabbit production industry. However, subfertility may be treated by using a simple intervention such as vitamin supplementation. Vitamin E and selenium (Se) are potent antioxidants that protect the male reproductive system. The aim of this study is to determine the effects of vitamin E and Se on testicular size, semen quality and freezability, antioxidant activity, testosterone levels, and fertility in subfertile rabbits. Twenty-one New Zealand rabbits were classified as subfertile rabbits based on their semen characteristics and fertility records. The rabbits were randomly allocated into 3 equal groups (G1: control; G2: injected with Vit E 100 IU/head + Se 0.1 mg/kg b.w.; G3: injected with Vit E 200 IU/head + Se 0.2 mg/kg b.w. once weekly for 8 weeks).Once weekly for 8 W, blood samples were collected to measure serum testosterone level and total antioxidant capacity (TAC), and semen samples were collected by artificial vagina to assess the quality of fresh and frozen semen. At the 8th week of the study, 150 multiparous does were artificially inseminated with fresh semen to assess the fertility of rabbits after treatment; 50 does for each group. At the end of the study, rabbits were slaughtered to assess testicular morphometry. Fresh and post-thaw semen quality parameters were significantly (p < 0.05) higher in G3in comparison with G2and G1, respectively. Also, testosterone level was significantly (p < 0.05) increased at the 2nd week in G3in comparison with other groups. Conception and kindling rates were significantly (p < 0.05) higher in does which were inseminated with semen fromG3. In conclusion, injection of vitamin E and selenium at a higher dose (G3) improved the testicular morphology, quality of fresh and post-thaw semen, and most importantly, the fertility of subfertile rabbits.

Keywords: Fertility; Freezability; Rabbits; Selenium; Subfertility; Vitamin E.

Fig. 1

a, b Effects of VitE and Se injection at different doses on the serum concentrations of testosterone and total antioxidant capacity (TAC). G1: n = 7, control group. G2: n = 7, rabbit injected with Vit E 100 IU/head +Se 0.1 mg/kg b.w. G3: n = 7, rabbit injected with Vit E 200 IU/head +Se 0.2 mg/kg b.w. Values are means ± SEM. ^.*,**,***Values in each parameter are significantly different at least at P < 0.05 between the groups at the indicated time. ^{a b,c}Values represent significant (P < 0.05) time differences within treatment during the study. Treatment: P < 0.05; Time: P < 0.05; Treatment * Time: P < 0.05

Fig. 2

In vivo reproductive performance of rabbit does were inseminated with rabbit semen after injection of Vit E and Se at different doses for 8 weeks. G1:n = 50, control group. G2: n = 50, rabbit does were inseminated with rabbit semen that injected with Vit E 100 IU/head +Se 0.1 mg/kg b.w. G3: n = 50, rabbit does inseminated with rabbit semen that injected with Vit E 200 IU/head +Se 0.2 mg/kg b.w. Values with different superscripts a,b, and c indicate a significant difference (P < 0.05)

Fig. 3

Effects of VitE and Se injection at different doses on the testicular morphometry of rabbits. G1: n = 3, control group. G2: n = 3, rabbits injected with Vit E 100 IU/head +Se 0.1 mg/kg b.w for 8 weeks. G3: n =3, rabbits injected with Vit E 200 IU/head +Se 0.2 mg/kg b.w for 8 weeks. Values in each parameter with different alphabetical superscripts are significantly different at least at P < 0.05