Breeding rotation calculator — how often to rebreed

Stagger your breeders and you get young at a steady interval instead of all at once. This works out that interval, what it yields in a year, and the part usually left out: what the rotation costs the mothers, and how many replacements it quietly requires.

The numbers favour the tight rotation. They are not the whole answer.

It would be tidier if the kind rotation were also the profitable one, and it is not. Rebreeding early produces more young per year, and because the female is producing so many more of them, it also feeds each one more cheaply — she eats roughly double while lactating, but she is lactating for far more of a year that yields far more animals. On output and on feed, intensive wins, and a calculator that told you otherwise would be arranging the arithmetic to reach a conclusion it had already picked.

What it costs is not in those columns. She is feeding one litter while carrying the next, in negative energy balance for most of her life, and that life is about a year rather than three. Replacements are cheap in a spreadsheet — three does a year against two hundred young — so the sums will never make the case on their own. It is a real trade-off between what the farm earns and what the animals endure, and it is yours to make with the figures in front of you rather than hidden behind an average.

The middle is where most people who do this for a living end up, and it is what this app's protocol suggests: rebreeding about eleven days after kindling for rabbits gives a 42-day cycle, keeps the female in reasonable condition, and has the practical virtue that every job falls on the same weekday. Not the most productive, not the gentlest, and defensible on both counts.

One more thing the numbers hide: a tight rotation has no slack. A female that misses, a litter lost, a week of illness — on a 62-day cycle those are absorbed, and on a 32-day cycle they arrive on top of an animal already at her limit.

First-timers are not on the rotation yet

A female having her first litter should not be rebred on the tight schedule, whatever the rest of the herd is doing. She is still growing herself, and the litter she is feeding is competing with that. Give her a longer interval on the first cycle and bring her onto the rhythm from the second — which has the useful side effect of staggering her against the others, which you wanted anyway.

One male is not a plan

A buck or ram covers far more females than a smallholding keeps, so he is never the constraint on paper. He is a single point of failure and he is all of your genetics: every young animal you keep back is half-related to every other, and by the second generation you are choosing between inbreeding and buying in. If a rotation is going to run for years, the second male matters long before the second female does.

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