An 'amaizing' season
It's been a bumper season for maize and other supplements in the eastern Bay of Plenty.
Many are reporting higher than usual empty rates and are asking themselves what went wrong during mating?
While it is important to acknowledge that every farm is unique and there is no single answer to the question, a couple of factors seem to stand out. These are cow condition at calving and lower feed intakes over last season’s mating period.
Cow condition at calving
The summer and autumn of the 2021-22 season was particularly hard on cows.
A prolonged summer dry coupled with the promise of a great payout meant that a significant number of farmers milked on longer than they would have in a normal season. Cows had an insufficient time to reach body condition score (BCS) targets and there was less feed on hand for the 2022-23 milking season.
As a result of these factors, cows cycled later and there was a shorter period to get cows in calf. Malcolm Ellis, LIC, General Manager markets, reported in the last Dairy News that national submission rates were down 1.3%. There is strong scientific evidence which says that cows in BCS 5 at calving will cycle 8-10 days earlier than cows in BCS 4, so achieving target condition scores makes very good sense if cows are to get in calf easily.
Spring feeding
The other factor farmers and vets have attributed lower in-calf rates to, was the cold, wet, sunless spring. While many farmers reported having enough grass, it would appear from spring milk production figures and mating results that many cows were underfed leading up to, during and immediately after the mating period.
While it may have appeared there was enough grass, I suspect that the wet conditions resulted in poorer pasture utilisation and this combined with lower drymatter and energy concentration of the pasture, meant less energy was consumed.
On some farms, especially those with a short AB period, the sheer volume of late cycling cows, including those which had returned to service, was too high for the number of bulls on hand.
Maize silage - a great tool
For those farms who have had disappointing mating results, it is important that this isn’t repeated in the coming season. Maize silage is an incredibly valuable tool in a farmer’s toolbox to help achieve target BCS. Work done at DairyNZ’s Lye farm showed that it was one of the most efficient feeds at putting condition on cows.
Depending on breed, cows require between 110 kgDM (small Jersey) and 180 kgDM (large Friesian) of maize silage to put on 1 BCS. To achieve the same BCS increase from autumn saved pasture requires 145 kgDM and 225 kgDM for Jerseys and Friesians respectively. Feeding maize silage to put BCS on cows simply makes sense.
I wouldn’t normally recommend feeding maize silage in spring when there appears to be enough pasture. However, in cold wet springs like the last one, it is important to take into account the fact that pasture utilisation and energy intake can be lower and as a result cows may be underfed. In these conditions, maize silage is a valuable tool to make sure that cows receive enough energy to keep them cycling and to prevent them going anoestrous.
If you need any more information or would like someone to help you understand what may have gone wrong with the mating performance on your farm, get in touch with your consultant, vet, animal breeding representative or one of our Forage Specialists (visit pioneer.nz).
Ian Williams is a Pioneer forage specialist. Contact him at This email address is being protected from spambots. You need JavaScript enabled to view it.
