Review of the alternatives to castration and spaying of ruminants

Summary

Surgical castration is a long-entrenched traditional husbandry intervention for cattle, sheep and goats.  Surgical spaying only occurs in cattle. Finding alternatives and thereafter doing things differently on-farm, by conviction, will not come “naturally” to production livestock owners/managers. However, neither did accept the polled condition (replacing horns) reality for the red meat industry during the 20th Century! 

This review, in acknowledging this background reality, has recommended transitional arrangements e.g. channel webbing, and husbandry adaptation eg grow out and marketing of entire young male progeny, to allow industry to more easily adapt to and manage that external change whilst the R&D pipeline delivers!

This will allow incremental progress towards the necessary social (community) contract goal of replacement of these surgical interventions in older animals, whilst allowing their retention in the young  (<3-6 months) being the watershed age in current welfare negotiations.

The very fact of the current welfare standards and guidelines negotiations and industry participation therein, foreshadows a changing future reality moving inexorably towards accommodating some of the current and likely future animal welfare community expectations. In this pursuit, necessary change and productivity improvement must be locked together, so that industry benefits most from the external, even unwelcome, pressures for that necessary change. The breeding of bare breech sheep is the “mulesing debate” equivalent scenario. 

The capacity to research and develop a preferred animal welfare future for the industry over the next 5 years led to this review in 2013. The aim of MLA was to refine and develop the R&D program already underway to equip industry with viable alternatives that could effectively replace spaying and castration over time. 

These two procedures (castration and spaying) deliver contraception/sterility to the majority of males (eg steers) and selective sterility/contraception to cull heifers/cows being excluded from the breeding herd for genetic selection, age culling and/or economic (cash flow) reasons. The aim of any replacement alternatives should encompass the same goals AND enhance productivity through improved herd performance, seasonal management control/efficiency or cost savings e.g. labour. 

The project brief was to review the scientific literature together with the current portfolio of relevant projects and to make recommendations identifying promising areas for the R&D program through to 2017, cognisant of identifiable risks for success and failure.  

Following an initial half-day issues scoping meeting with key current researchers in Brisbane, the literature review process took a blank page starting point and developed a broad keyword based search strategy, largely directed at contraception in man and animals. Relevant reviews were identified and key topic areas defined and explored. A broad sweep of technologies were investigated including both “central”, eg GnRH, and “peripheral” gonad targeted mechanisms eg zona pellucida vaccines.  

Overall the conclusion was reached that the science is “looking good” for contraceptive reproductive control given multiple global drivers for research, including human population control, wildlife conservation and management, urban stray pet/pest control AND extensive livestock management. These diverse drivers currently engage a highly competitive and targeted global workforce of scientists and researchers both academically and commercially focused. This is evident in the review content.

However, focused additional R&D effort in the less emphasised field of production animals is certainly indicated, to exploit known basic scientific technologies, refine these approaches and deliver novel applications and application studies critical to final commercial success for livestock producers.