FARMING: The benefits of A.I and synchronisation

The ability to select for traits from high genetic merit A.I bulls with reliable figures due to genomic testing and a large number of progeny is a well-advertised and widely accepted benefit for using A.I. The benefits of calving ease and calf vigour provide the opportunity for a quick improvement in calf mortality rates while for those rearing their own replacements, an improved herd fertility will also contribute to an improved weaned calf crop percentage.

The A.I of heifers alone provides the opportunity to select a sire for ease of calving as it is often not economical to keep a stock bull just for heifers. A.I in heifers also enables the use of sexed semen and the selection of maternal traits which offers the opportunity to breed replacements from the animals with the highest genetic merit in a herd and the best conception rates.

As mentioned above the three week in calf rate is a key factor in fertility efficiency and the profitability of a beef enterprise.

By synchronising animals we can achieve two services within this three week period (Day one – A.I usually and day 20 – with stock bull usually if not held to A.I). The use of a progesterone releasing device such as a PRID or CIDR also aids in assisting cows return to cyclicity which means that CIDRs can be used to improve the three week in calf rate in early – mid season cows but also to shorten the length of the calving period for later calving animals which might traditionally have been bred at the end of the breeding period or not bred at all.

We get asked what conception rates to expect from A.I. and this can be tricky to answer! The industry average is 60%- 65% though the range is large year on year (50-80%) and there are a large number of factors.

Body condition score at calving (>2.5) and a rising plane of nutrition is very important and the number of days since calving will also affect conception. Trace minerals have a role to play (copper in particular) but in general are of much less significance than an energy deficit.

Furthermore herd fertility, adherence to the timings of a synchronisation programme and the A.I tech variability and the number of services all affect outcomes. A standard PRID synchronisation protocol with a single fixed time AI (FTAI) service will have four animal handlings (insert PRID +/- GnRH, Prostaglandin injection, CIDR removal and FTAI.

This can be reduced to three using a variation of the protocol but also risks a slight reduction in conception rate.