What questions should you ask if you find out you have a deleterious allele in your herd?

• A. How deleterious is it? What is it costing me? How much of the herd would you need to cull to remove it? What is the value of the other genes in your herd? Is clean stock available? Can you manage it?
• B. Is clean stock available?
• C. What is the best strategy for culling the entire herd?
• D. Could you raise more replacements?

Answer: (A)

When a deleterious allele is found in a herd, the practical approach is to weigh how severe the allele is, what economic impact it has, and whether you can realistically remove it without sacrificing too much production. The best option asks several integrated questions: how deleterious is it and what is it costing you, because this sets the urgency and the budget for management; how much of the herd would need to be culled to remove it, which defines a feasible plan and helps avoid excessive losses; what is the value of the other genes in your herd, since you don’t want to throw away beneficial traits that coexist with the allele; whether clean stock is available, which determines if you can replace affected animals without spreading the allele; and whether you can manage the plan, since successful control requires testing, selective mating, and ongoing management. Together these questions address the full picture—economic impact, genetic value, and practical implementation—making it the most comprehensive path.

Focusing only on clean stock misses the cost and feasibility aspects; proposing to cull the entire herd ignores practicality and valuable genetics; and simply raising more replacements doesn’t tackle the deleterious allele and could perpetuate risk without a plan for testing and selection.