Activity of Different Types of Cactus Forage on Testicular Function and Morphology of Sheep Subjected to Environmental Heat Stress.

Abstract

In this study, we aim to analyze whether supplementation with cactus has the potential to minimize the testicular damage caused by heat stress, assess which of the three cactuses would have the best potential, and suggest a possible pathway (oxidative or hormonal) for the action of cactus on the testicular parameter alterations caused by heat stress. Thirty-two male lambs, of the Santa Inês type, not castrated, approximately six months old, and averaging 21.0 ± 2.0 kg body weight, were divided into four groups, as follows: G1, which was fed an elephant grass hay diet (control); G2, with a diet with partial replacement using small cactus forage (Opuntia cochenillifera) (SMALL); G3, which was fed Mexican elephant ear (Opuntia stricta Haw) (MEE); and G4, which was fed IPA Sertania (Nopalea cochenillifera Salm Dyck) (IPA) for 63 days. After slaughter, blood and testicles were removed. The right testicles were fixed for histological analyses, and the left testicles were stored in the freezer for oxidative stress analyses. Serum testosterone, T3, and T4 levels were analyzed. The body weight of animals treated with cactus forage was higher than in the control group. However, the gonadosomatic index did not differ among experimental groups. Heat stress triggered the degradation of testis tissue in all experimental groups. The testicular degeneration process was characterized by tubular atrophy, reduction in germ epithelium height, germ cell vacuolization and necrosis, Sertoli cell vacuolization, germ cell scaling of the tubular fire, and increased intertubular space. The three different cactus forages used in this study had different weaknesses regarding their antioxidant defenses, hormonal levels, and histopathology. However, it is important to highlight that the IPA group had lower qualitative changes in the intertubular areas than the other experimental groups. The testosterone level increased in MEE (Opuntia stricta) and IPA groups, while T3 and T4 increased in SMALL (Opuntia cochenillifera) and IPA groups. The malondialdehyde, an important marker of lipid peroxidation, was reduced only in the IPA group. The testosterone level increased in MEE and IPA groups, while T3 and T4 increased in SMALL and IPA groups. In conclusion, heat stress triggers several histopathologies in testis tissue, and IPA cactus (Nopalea cochenillifera) was the most appropriate supplementation for reducing the damages, compared with an elephant grass hay diet or small cactus forage and Mexican elephant ear supplementation.