Examination of the use of intraovarian administration of CaCl2 and zinc gluconate as potential chemosterilants in Bos indicus heifers.

ABSTRACT

OBJECTIVE: To investigate if administration of potential chemosterilants by transvaginal, ultrasound-guided intraovarian injection is an alternative to surgical sterilisation. DESIGN: Randomised control study. METHODS: Bos indicus heifers were treated with intraovarian injections of saline (n = 10), CaCl2 (n = 10), zinc gluconate (ZG; n = 10) or a combination of CaCl2 and ZG (CaCl2 + ZG; n = 10). Heifers were exposed to a bull from 82 to 84 days after treatment and slaughtered between 364 and 396 days after treatment. RESULTS: After treatment administration, the concentrations of haptoglobin and anti-Müllerian hormone and the total oocyte counts did not differ (P > 0.150) between treatments. Pain responses were observed in heifers treated with ZG and CaCl2 + ZG but not in heifers treated with saline or CaCl2 . Total ovarian mass at slaughter was less in heifers treated with CaCl2 compared with the other treatments (P < 0.05). Complete regression of one ovary was observed in 40% (4/10) of the heifers treated with CaCl2 . Pregnancies were recorded in ≥ 70% of heifers administered each treatment. CONCLUSION: Treatments used in this study were not able to sterilise most of the B. indicus heifers, but treatment with CaCl2 has the potential to cause complete ovarian atrophy without causing detectable pain.