In a commercial suckler herd the generally accepted targets for productivity are:

1, A 365-day calving interval

2, Just 5% culled as barren

3, A 95% weaning rate

4, Compact calving, with 80% within six weeks (65% in first three weeks)

5, Heifers calving in at 24 months

6, Replacement rate 16-18 %

7, Breeding for genetic improvement

8, Match calving time to feed availability

These targets will also increase the efficiency and therefore sustainability of the herd with a lower environmental impact per kg of beef produced. Targeting a compact calving period is important because it has many advantages including:

• Cows have longer to recover before going back to bull

• Improving calf weaning weights

• Reducing the disease risk in younger calves

• Shortens additional extra labour requirements

It is also relevant to consider that AHDB estimates the cost of keeping a suckler cow for a year is between £450 and £800 and the calf is the only source of income to cover this cost.

If calves are born earlier in the calving block, they will be older and heavier at weaning and result in the cow having more time to recover and more opportunities to get back in calf.

A cow calving down in good BCS (body condition score) takes in the region of 50 days to first ovulation and this can be significantly longer in cows with poor BCS which makes achieving a 365 calving period very challenging in some circumstances.

AI and synchronisation

AI allows increased choice of bulls meaning sires with appropriate EBVs (estimated breeding values) can be selected for genetic gain as well as reducing calving problems, plus sexed semen can be utilised to breed replacements amongst other benefits.

Heat detection can be time consuming and difficult and therefore synchronisation protocols that allow a fixed time insemination are commonly used. These tend to use a progesterone device to restart cyclicity which also has the advantage that if cows do not hold to the AI they should come bulling three weeks later.

There are numerous protocols available and your vet can advise you which is most appropriate for your herd and farm.

Fixed Time Artificial Insemination (FTAI) using synchronisation protocols can therefore be used:

• To utilise superior genetics to optimise calf value

• To tighten up the calving block both by serving cattle early in the breeding season as well as bringing forward the late calving cows to calve earlier in the calving season

• Careful selection of sires for heifers

• To manage the number of bulls required.

Farmer, Alec Mitchell, of Hallcroft Farm, decided to utilise the sync-straw AI service that Clyde Vet Group, Stirling, was offering across 320 animals – 246 cows and 74 heifers. Alec and I discussed the options and chose the protocol detailed below for ease and convenience, which was important with the number of animals involved.

At the start (day 0) every cow was scanned to check she was clean and cycling since her last calving, and all heifers were assessed. Heifers considered to be too small or with poorly developed reproductive tracts were not synchronised for breeding at this point.


• Average days calved at sync date: 57 days (range 18-91)

• Average conception rate to AI, 63% (61% heifers, 64% cows)

• Average days pulled forward all cows: nine days

• Average days pulled forward for cows calved <42d at syncrony: 21 days

• Significant bull saving

• Native breeds performed very well


The AI conception rate was good, especially for the number of cows per batch and using only three handlings, but not excellent, so the chaser bulls still had some work to do.

Only four bulls were used, of which one was questionably sub-fertile and one went lame. Therefore, the in-calf rate of the bulled cows was excellent. Increased progesterone levels after a synchronisation will have had a part to play here.

The 320 cows would normally have required 11-13 bulls (1:30 ratio with a spare), so that indicated a saving on purchasing seven to nine bulls.

Late calving cows (<42 days calved at synchrony start) were pulled forward on average 21 days, therefore the calving block had been tightened significantly. This benefit will be seen at calving next season as there will be a more compact calving block with fewer outliers.

A variety of cow breeds were involved, of which the native breeds had the highest conception rate, notably Hereford cross being by far the best.

Some 91% of cows and 97% heifers were in calf after nine weeks (AI being start date). In theory, this could have been higher if all the bulls were sound, or one more bull was used.

The results speak for themselves, but significant credit goes to Alec for seeing the value of investing in the service, along with excellent organisation and manpower on the farm to facilitate the handling of larger batches on multiple sites. The largest being 180 cows and heifers in three groups over two sites without a glitch!

In answer to the original question is using AI in commercial beef herds economically viable then the answer is 'Yes'!

How did Alec Mitchell find the process:

Have you used much AI before?

I had a three cows AI’ed a few years ago and only one held, so I went off the idea.

What were your main concerns?

Getting the timings correct, as I had heard so many different opinions regarding timing and whether to AI once or twice.

Why did you decide to go for it?

I wanted to utilise the best genetics that were available.

How much hassle was it is?

Fairly simple once we got in the swing of it and the hydraulic crate made a big difference. It was labour intensive on the AI-ing day to keep it running smoothly and it would sometimes clash with other jobs, but we saw it as a good opportunity to get other vaccines up to date.

Were you pleased with the results?

Yes, very.

Will you do it again?

Yes, Hamish it will be very busy this next mating season!