The Breeding Season, the Bull and Reconception

#Thirty-eight bulls, three of them fit

At Moretele, researchers examined 38 communal bulls. Mean scrotal circumference was 37.63 ± 3.42 cm. Mean progressive sperm motility was 27.39 ± 15.81%, against a requirement of at least 30%. When the results were totalled, only 3 of the 38 — 7.9% — had adequate semen quality.

The other 35 carried severe scrotal and preputial lesions caused by Amblyomma hebraeum and Hyalomma rufipes, and the authors concluded that this tick damage had a more serious effect on fertility than the contagious diseases they also tested for (McCrindle et al. 2019, JSAVA).

Now ask the question that matters. If your bull were one of those 35, how would you know? He walks. He eats. He mounts cows. Nothing about him looks wrong until fourteen months later, when the calving pens stay empty and everybody blames the drought.

#Get the bull right first

Fertility traits come before growth traits when you buy: age at first calving and inter-calving period in the female line, and scrotal circumference. Cap mature cow weight rather than maximise growth, as Lesson 2 argued. Read EBV accuracies, not just values.

Then require the paperwork. The South African Veterinary Association has endorsed a bull breeding soundness certification standard for natural-service sires and semen donors (Theriogenology). A current certificate is the gate a bull passes through before he is bought and before each season — and given the Moretele findings, a scrotal examination is an annual event, not a once-off.

Beyond the reference figures the Moretele authors themselves worked to, this course will not set pass/fail thresholds for your bull. Those belong on the certificate and to your veterinarian, who has the animal in front of them.

Match numbers to the bull's age. The ARC's guideline is not one ratio but three (Bergh 2004):

Adjust downward for poor libido, inexperience, large or broken paddocks, poor visibility, long walks to water and heat. Independent South African smallholder work lands in the same place, finding 1:30 the ideal, classing 1:15 as under-supplied and 1:70 as over-extended, and linking low ratios directly to extended calving intervals (Nkadimeng et al. 2022).

#When to mate, and why it is a rainfall decision

The authority here is the ARC's own guidance, and it is more specific than the "60 to 90 days" everyone quotes.

Season length. "A breeding season should not be longer than 90 days." Take 285 days as average gestation: to hold a 365-day calving interval a cow must conceive within 80 days of calving, so 75–80 days is already better than 90. The stated ideal is 65 days — three oestrus cycles — for lactating cows, and 45 days, two cycles, for heifers and dry cows (Bergh 2004). Teach 65 and 45 as the target and 90 as the outer limit. "60 to 90 days" is a summary of the recommendation, not the recommendation.

Timing. Choose the time at which cows reach optimum condition for breeding — usually about three months after the month of highest rainfall. And for calving: "the best re-conception is achieved if cows calve about one month before to about one month after the first effective rains have fallen." The stated ideal calving time is six to eight weeks before adequate green grazing can be expected.

Notice that the whole principle runs through condition, which is why the winter feed year decides the mating season. Dry-season veld runs at 2 to 6% crude protein against a rumen threshold of about 7%, below which intake itself falls (Virbac SA). A cow that came out of August thin is not made ready by a bull arriving in November.

Read that carefully, because the ARC does not sit on the fence. It leans slightly early — a cow calving six weeks before the green comes has recovered and is cycling when the grazing arrives. The Zietsman school pushes later, deliberately, to protect cow condition. Both are defensible; what is not defensible is having no season at all.

The regional table is the single most useful thing in that paper:

The "15 November to 15 February" season quoted everywhere is Bergh's worked example for an area where first effective rains fall in October. It is not a national prescription.

What each error costs. Bergh names both, and they are not symmetrical:

• Too late. Calves are too small to use the dam's peak milk off peak summer pasture, so weaning weights fall — and cows in better condition throw heavier calves, which raises dystocia risk. You lose at both ends.
• Too early. Cows calve too long before adequate grazing, lose too much condition feeding a calf on standing hay plus lick, and reconceive at a lower rate. That is next year's calf crop, paid for this year.

#Making the season real

A season only does its work if it ends, and the ending is where most farms fail.

Point 3 is the one people negotiate with, and it is the point of the whole exercise. Without a defined season you cannot cull a late cow, because you cannot see her. A cow calving in March is not visibly a failure if calves arrive all year. Give the herd a 65-day window and she becomes obvious in a fortnight.

#Where you actually are

South Africa has a benchmark study for this, and it makes uncomfortable reading. Nkadimeng and colleagues analysed 3 694 cow records from 40 smallholder herds across the Eastern Cape, Free State, Limpopo, Mpumalanga and North West (Animals 12(21):3003):

The same paper records a 65% calving rate as the commercial-herd standard and an 85% national average recommended by the department, and a working management target for inter-calving period is below 365 days (Herdscape).

Read the middle column honestly. Those are not standards of good practice. They are the 25th or 75th percentile of this same smallholder dataset — a "target" pregnancy rate of 54% is simply what the better quarter of these herds achieved: a realistic next step for that population, not a definition of good.

What the table really shows is the size of the gap. A 608-day calving interval is about 0.6 calves per cow per year, and the distance from 608 days to 425 is roughly half a calf per cow per cycle. That is a management gap, not a genetics gap.

One more caveat. The much-quoted "62% commercial, 48% emerging, 35% communal" calving split traces back, for its first number only, to a decade-old published estimate that states no method; the other two figures, and the "50–55% national weaning percentage against an 80% target", could not be traced to a primary source for this course. Do not quote them as measurements.

#Early weaning as a quantified trade

When the season fails or a cow's condition is sliding, the strongest lever you have is to take the calf off. Lactation is the largest demand on her, and removing it is what restores condition and shortens the anoestrous interval.

South Africa has one quantified comparison. In Bonsmara cattle, early weaning at about 90 days against conventional weaning at 205 gave weaning weight of 210.38 kg against 237.11 kg — 27 kg lighter — and an inter-calving period of 347.59 days against 419.25 — 72 days shorter (Jammer, Lombard & Jordaan 2025).

State the trade in one line: you give up 27 kg of calf to buy back 72 days of cow. Which of those your business is short of is a question about your feed year, not about weaning theory. In a failed season, 72 days of cow is worth far more than 27 kg of calf. In a good one it may not be.

Two honesty notes before you build a policy on it. That study is one farm, 152 Bonsmara cow-calf pairs, retrospective and observational, and the authors say plainly that the two groups "were not compared statistically". The early-weaned group was also entirely first-calf heifers — exactly the animals whose calving interval responds most to removing the calf — so the design flatters the result. And the calf you take off at 90 days needs a starter ration the veld will not supply.

Treat early weaning as a well-founded physiological principle that is poorly quantified in South Africa: a real tool for a bad year, not a default.

Here is what to do before the next lesson. Find your bull's last breeding soundness certificate. If there isn't one, book the examination now rather than in November — and while you are on the phone, write down the date of the first effective rains for each of the last five seasons. Those two actions decide more of your income than any breed decision you will ever make.