الفهرس 
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Abstract
This study is designed to investigate how dietary boron (B) supplementation affected testicular function, thyroid activity, some blood minerals, growth and immunity in male goats.
In this study, twelve male goats were classified randomly into two groups (6 animals each). The first group acted as a control that was fed the normal basal diet. The animals in the other group were fed the basal diet containing a 70 mg B/kg diet. To obtain that, the basal diet was supplemented with a 400 mg BA/kg diet. The work extended for 6 months, during which the animals were fed their corresponding diet.
The bucks were weighed at different intervals during the experiment (Zero-day, 12th, 18th and 24th weeks) using electric balance and it was taken as a measure of growth.
Serum levels of B, testosterone, thyroid hormones (T3 and T4) calcium, magnesium and gamma globulins were estimated.
Testicular biopsies were collected for the estimation of CYP17A1 mRNA expression level and histopathology.
The results indicated that feeding male goats with a diet supplemented with B for 6 months resulted in marked elevation (P<0.05) of the serum concentration of boron (B) in comparison to the control group at the end of the experiment. In addition, the mean values of body weights didn’t show any significant differences between the control and B groups (P>0.05).
The findings also illustrated that supplementation of male goats’ diet with B resulted in a significant increment of serum testosterone levels on the twelfth, eighteenth and twenty fourth weeks in comparison to the control group (P<0.05). Furthermore, the fold change of serum testosterone levels in comparison to zero-day was significantly higher than the control value.
The serum levels of T3 were significantly increased with B supplementation on the twelfth week when compared to control goats (P<0.05). However, on the eighteenth and twenty-fourth weeks, the serum levels of T3 were comparable in both the B and control groups. Also, the data revealed that B supplementation didn’t induce any changes in the serum T4 levels in comparison to control animals. The fold changes of serum T3 and T4 levels on the 24th week in relation to zero-day were equivalent in both groups.
The findings revealed a significant (P<0.001) increment of the expression level of CYP17A1 mRNA with B supplementation compared to the control group.
The serum levels of calcium and magnesium in both the control and B groups didn’t differ significantly along the different time points of the experiment (P > 0.05). However, on the 24th week, the serum magnesium level showed a noticeable increment following B supplementation in comparison to the control group (P < 0.05).
Data also showed that, in comparison to the control group, there were not any significant differences either in the heart girth, body length, the lengths of both fore and hind limbs or testicular circumferences following B supplementation along the different time intervals of the experiment (P > 0.05). Just, at the 18th week, body length revealed higher values in the control group. In addition, at the twelfth week, the length of the hind limb significantly increased with B in comparison to the control group.
According to the findings, there was no significant difference between the two groups’ adjusted serum gamma globulin densities (P = 0. 814).
Boron supplementation succeeded remarkably in improving the testicular architecture and appeared with normal morphology and included seminiferous tubules lined by normal spermatogenic cells and Sertoli cells. Furthermore, the aforementioned findings were confirmed by the morphometry results. In this regard, the diameter of seminiferous tubules was significantly increased with B supplementation compared to the control group (P<0.05). The height of spermatogenic cells was also increased significantly with B supplementation. However, the number of seminiferous tubules per microscopic field was observed to be comparable in both groups.
Because B supplementation significantly increased serum testosterone levels, it is possible to conclude that B supplementation is a promising candidate for enhancing male reproductive activity. It significantly increased the mRNA expression of CYP17A1 gene, indicating that B can aid in the increase of serum testosterone levels. The morphology of testicular tissue was also significantly improved, supporting our hypothesis that B could increase male fertility. Furthermore, the addition of B to a male goat’s diet did not seem to have any negative effects on thyroid activity, growth, blood calcium and magnesium, or immunity. Thus, a dose of boron might be safely added to the diet of male goats to increase their potential for reproduction.