title: Immunocontraception for managing feral cattle in Hong Kong.
abstract: 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.
authors: National Wildlife Management Centre, Animal and Plant Health Agency, York, United Kingdom.
authors: Giovanna
authors: G
authors: Massei
authors: Agriculture, Fisheries and Conservation Department, Animal Management Division, Hong Kong SAR, China.
authors: Ka-Kei
authors: KK
authors: Koon
authors: Agriculture, Fisheries and Conservation Department, Animal Management Division, Hong Kong SAR, China.
authors: Steven
authors: S
authors: Benton
authors: The School of Veterinary Medicine, City University of Hong Kong, Hong Kong SAR, China.
authors: Richard
authors: R
authors: Brown
authors: National Wildlife Management Centre, Animal and Plant Health Agency, York, United Kingdom.
authors: Matt
authors: M
authors: Gomm
authors: USDA APHIS National Wildlife Research Center, Fort Collins, Colorado, United States of America.
authors: Darcy S
authors: DS
authors: Orahood
authors: Food and Environment Research Agency, York, United Kingdom.
authors: Stéphane
authors: S
authors: Pietravalle
authors: USDA APHIS National Wildlife Research Center, Fort Collins, Colorado, United States of America.
authors: Douglas C
authors: DC
authors: Eckery
mesh_terms: D000818:Animals; D000906:Antibodies / Q000097:blood; D001824:Body Constitution / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D002417:Cattle / Q000502:physiology*; D003269:Contraception, Immunologic / Q000379:methods / Q000662:veterinary*; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000276:immunology*; D006723:Hong Kong; D007247:Infertility, Female / Q000139:chemically induced / Q000662:veterinary*; D008198:Lymph Nodes / Q000187:drug effects; D011247:Pregnancy; D018709:Statistics, Nonparametric; D013997:Time Factors; D014611:Vaccination / Q000379:methods / Q000662:veterinary*; D018074:Vaccines, Conjugate / Q000276:immunology*
chemical_list: D000906:Antibodies; D018074:Vaccines, Conjugate; D007987:Gonadotropin-Releasing Hormone