Rapid Evidence Assessment – Castration in Lambs

In total, ten castration practices were identified and assessed (see below table). For practices where sufficient evidence was identified, a narrative summary was produced. Each summarises the impacts of a practice across primary areas of concern to both farmers and consumers, such as animal welfare and additional costs borne by the producer and presents the information in a farmer-facing format covering: what the practice is, what best practice looks like, where it is most applicable and how robust the evidence base is. For practices where there was limited evidence, a brief discussion was provided, summarising what the practice is, highlighting the evidence gaps.

The Problem     

Castration is a routine husbandry procedure performed on some male lambs with the practice governed by a number of different laws in the UK. There is no public information available at a national level on the proportion of lambs castrated across the UK, although there appear to be regional differences, with anecdotal evidence to suggest that fewer lambs are castrated in Wales than England.

The key reasons for castrating ram lambs include welfare and behavioural management, such as preventing fighting between rams, and being able to keep male and female lambs together whilst mitigating the risk of unwanted pregnancies. Castration reduces the risk of ‘ram taint’, which is an alteration in the qualities of the meat which develops due to the presence of testosterone and causes an unpleasant taste. This creates issues for the supply chain due to customer expectations and the impact of poor-quality products on repeat purchases of lamb products.

There is increasing interest in how castration practices could be reduced, refined and or replaced. AHDB funded this project to collate the evidence on the impact of castration practices on lamb welfare and productivity, farm profitability and environmental sustainability to provide practical evidence-based guidance that supports on-farm decision making. The project outputs provide an overall picture of the evidence landscape for practices applicable to castration in lambs (across all production systems in England) to enable an evaluation of what practices work for improving lamb productivity and welfare.

Aims and Objectives      

The objectives of the project are to:

• Identify and provide evidence on the range of castration practices used across the full range of English sheep production systems (hill, upland and lowland)
• Provide evidence on welfare, productivity, profitability, and environmental sustainability metrics (measures/indicators) in a format which is accessible to farmers
• Identify gaps in the evidence and future technologies which would support future improvements in lamb welfare and productivity
• Provide context as to how each castration practice discussed relates to existing legislation and to farm assurance schemes

Approach           

A rapid evidence assessment (REA) is an approach to review an evidence base under time or resource constraints. It applies the same methodological steps as a more comprehensive literature review but makes concessions in terms of the number of databases searched, the quantity or type of evidence collected, or the amount of data extracted from each piece of evidence. This enables REAs to be delivered within a relatively short period of time while still providing a robust evidence summary. The REA methodology was used to generate and evaluate an evidence base of academic, grey and industry literature on the impact of different castration practices on lamb welfare, productivity, profitability, and environmental sustainability across the full range of English sheep production systems. This evidence base was then evaluated using a framework to answer the following questions:

• What the practice is
• What is the impact on animal welfare?
• What is the impact on productivity?
• What is the impact on profitability?
• What is the impact on environmental sustainability?
• Where does the practice work?
• How much does the practice cost?
• How can the practice be done well?
• What are the legal implications of the practice?
• How do farm assurance schemes manage the practice?
• How strong is the evidence for the practice?
• How the 3Rs (Replace, Reduce, Refine) could be applied
• Where can further information be found?