Boron is reported to cause fertility disorders in birds. We investigated the potential adverse effects of boric acid administered during embryogenesis on testicular development and spermatogenesis after hatching and puberty.

The fertilized eggs were divided into four groups. Three groups were injected with different concentrations of boric acid (1000, 1500, or 2000 ppm) dissolved in 9% NaCl into the egg yolk, and the control group received only a 9% NaCl injection. The evaluations were conducted at two time points: post-hatching day 1 and 26 weeks of age. Testes of one-day-old- and 26-week-old birds were subjected to morphological and stereological evaluations to assess the potential effects of boric acid on testicular development. Effects of boric acid on spermatogenesis and semen quality parameters were also investigated in 26-week-old birds. Finally, plasma FSH, LH, and testosterone levels were analyzed in all birds.No statistically significant differences were noted between one-day-old chicks and 26-week-old birds regarding stereological parameters. Likewise, no significant differences were detected among groups concerning Sertoli, germ, and Leydig cells. Semen quality parameters did not reveal statistically significant differences, and similarly, plasma LH and testosterone levels did not statistically differ between the study and the control groups. Comb height and plasma FSH levels were increased in experimental groups, compared to the control in 26-week-old birds. A single administration of different boric acid doses did not impact the testicular morphological features after hatching and puberty. In-ovo boric acid exposure quantitatively altered the numbers of the Sertoli, germ, and Leydig cells, respectively, but revealed no adverse effect on spermatogenesis. This study might contribute to further research targeting boric acid's multifaceted effects on the dynamics of spermatogenesis.