Dietary supplementation with 9% low-purity crude glycerine increases spermatocytes and sperm yield in bulls.

This study aimed to evaluate the effects of low-purity crude glycerine (LPCG) supplementation on spermatogenesis in bulls. Twenty-nine bulls with an average weight of 428.0 ± 32.11 kg and an age of 22 months were randomly assigned to five treatments based on the percentage of LPCG added to feed concentrate (0, 3, 6, 9, and 12% on a dry matter basis). The animals were kept in Brachiaria decumbens paddocks with a daily supply of concentrate (1% of live weight) for 88 days, after which they were slaughtered, and their testicles were removed and histologically processed. The following parameters were quantified: Sertoli cells, type A spermatogonia, primary spermatocytes in pre-leptotene and leptotene, pachytene spermatocytes and round spermatids, intrinsic spermatogenesis yield, Sertoli cell indices, total number of Sertoli cells (TNSC), TNSC per testicular gram, daily sperm production (DSP), DSP per testicular gram, total testicular sperm reserve (TSR), and TSR per testicular gram. The number of primary spermatocytes in leptotene and pachytene, round spermatids, and DSP per gram were higher in the 9% LPCG treatment group (P < 0.05) than in the control. The other parameters evaluated were similar between the treatments (P > 0.05). Supplementation of bulls’ diet concentrate with 9% LPCG improved the number of germline cells without affecting the intrinsic spermatogenesis yield, despite increasing DSP per gram of testicular parenchyma.