Massei Giovanna, Koon Ka-Kei, Benton Steven, Brown Richard, Gomm Matt, Orahood Darcy S, Pietravalle Stéphane, Eckery Douglas C
National Wildlife Management Centre, Animal and Plant Health Agency, York, United Kingdom.
Agriculture, Fisheries and Conservation Department, Animal Management Division, Hong Kong SAR, China.
PLoS One. 2015 Apr 9;10(4):e0121598. doi: 10.1371/journal.pone.0121598. eCollection 2015.
Conflicts between human interests and feral cattle in Hong Kong derive from growing numbers of free-roaming cattle. Public antipathy towards lethal population control led the local authorities to consider fertility control to reduce cattle numbers. This study assessed the potential side effects of the immunocontraceptive GonaCon on individual female cattle and established the effectiveness of GonaCon to induce infertility. We evaluated GonaCon in 34 captive cattle assigned to four groups: Control administered a sham solution; Webbed (surgically sterilized through removal of the oviducts), administered one dose of GonaCon; Webbed, administered one dose of GonaCon and a booster dose three months later, and Treated, administered one dose of GonaCon. The side effects of GonaCon were assessed by monitoring injection site, body weight, body condition, size of lymph nodes, body temperature, and feeding behaviour 1 week and 1, 3, 6, 9 and 12 months after vaccination and by haematological and biochemical variables at vaccination and three months post-vaccination. The effectiveness of GonaCon to cause infertility was monitored by quantifying anti-GnRH antibody titres and by using kits to detect cycling and pregnancy. GonaCon-treated cattle showed no injection site reaction, limping, or abnormal behaviour. No differences were observed in all physiological and welfare indicators between control and vaccinated cattle. All control cattle and 4 of the 12 cattle in the Treated group became pregnant. Cattle administered a booster dose had higher anti-GnRH antibody titres than cattle that received one dose. We concluded that GonaCon does not compromise the animals' welfare and is effective in reducing fertility in cattle. A booster dose is likely to increase the duration of infertility. Further studies are required to assess the feasibility and costs of immunocontraception for controlling free-roaming cattle populations.
香港人类利益与野生牛群之间的冲突源于自由放养牛数量的增加。公众对致死性种群控制的反感促使地方当局考虑采用生育控制来减少牛的数量。本研究评估了免疫避孕药物GonaCon对个体母牛的潜在副作用，并确定了GonaCon诱导不育的有效性。我们在34头圈养牛中评估了GonaCon，这些牛被分为四组：对照组注射假溶液；输卵管结扎组（通过切除输卵管进行手术绝育）注射一剂GonaCon；输卵管结扎组，注射一剂GonaCon，三个月后再注射一剂加强剂量；处理组，注射一剂GonaCon。通过在接种疫苗后1周以及1、3、6、9和12个月监测注射部位、体重、体况、淋巴结大小、体温和采食行为，以及在接种疫苗时和接种疫苗后三个月检测血液学和生化指标，来评估GonaCon的副作用。通过定量抗促性腺激素释放激素（GnRH）抗体滴度以及使用试剂盒检测发情周期和妊娠情况，来监测GonaCon导致不育的有效性。接受GonaCon治疗的牛未出现注射部位反应、跛行或异常行为。对照组和接种疫苗的牛在所有生理和福利指标上均未观察到差异。所有对照牛以及处理组12头牛中的4头怀孕。接受加强剂量的牛比接受一剂的牛具有更高的抗GnRH抗体滴度。我们得出结论，GonaCon不会损害动物福利，并且在降低牛的生育率方面有效。加强剂量可能会延长不育持续时间。需要进一步研究来评估免疫避孕控制自由放养牛群数量的可行性和成本。
