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23rd February, 2019


The Cheltenham festival each year heralds a break in breeding programmes for winter milk production systems and a resumption to spring breeding programmes which extend from early April through mid-May.

Breeding cows in mid-March is not a recipe for household social harmony as cows calve over the Christmas period. However, there are many farmers willing to start their spring breeding programmes in early April.

Farm fragmentation, availability of land to rent at economically justified long-term leases and skilled labour are presented as reasons to focus on a 14 to 16 week calving period. In contrast, the 6 week concentrated period, which has been proposed as yielding the greatest financial rewards is frowned upon by many at farm level.

Irrespective of the option chosen, there has to be a focus on herd health management at this stage of the calving season. Psychologically, many farmers will put in a valiant effort to manage cows correctly through both the dry cow and early lactation transition periods. These dictate approximately 80pc of herd health and future reproductive performance in the herd.

We need to be cognizant of the fact that there are still between 20 and 40pc of cows left to calve on many farms. These cows will tend to be the older cows and problem breeders from the previous breeding season. These cows will predominantly be in calf to beef sires, where there is an inherently greater risk of calving difficulty.

There is a greater risk that these cows will endure poorer management during the latter phase of pregnancy. As the weather improves and grazing conditions improve, the milking cow group get preferential access to grass.

As the dry cow group gets smaller, they are not fed fresh forage on a daily basis. Mineral supplementation is often neglected and the risk of mycotoxins increases. The management of forage pit faces become critical at this time of year where a combination of increased temperatures and reduced use of forage results in increased risk of mycotoxin contamination.

You cannot afford the risk of your late calving cows enduring health problems during the transition periods. Late calvers have to get off the starting blocks quickly to be fit for breeding within six weeks after calving. Cows calving early have an opportunity to recover if health problems have been an issue.

Ensure the late calvers have fresh silage fed on a daily basis with a mineral and concentrate balancer, which in the first place prevents body condition loss during the dry cow transition and addresses the risk of high potassium and ammonia silages.

Silage quality continues to be a major limiting factor to successful outcomes from the dry cow transition period. Slurry management is an issue here. As stock numbers increase there is a greater risk of heavier slurry applications on ground allocated for silage conservation.

The clinical outcomes suck as milk fever, ketosis, and retained afterbirths may be reduced by dietary supplementation. However, the subclinical outcomes are poor as revealed by scanning of the reproductive tract between 14 and 40 days post calving. Subclinical health impairments result in the same uterine infections with a consequent delay to return to normal heat cycles, poor pregnancy rates and ultimately poorer survival rates in a restricted breeding window.

Studies have also shown that the incidence of twinning will be greater in your late calving cows. Older cows have an inherently higher twinning rate. Secondly, problem breeders associated in the first instance with ovarian cysts will have an increased risk of twinning when this problem has been resolved.

Scanning your cows will have identified those cows carrying twins when conducted prior to 110 days of pregnancy. Improved nutritional management of cows carrying twins will reduce the risk of poorer calf and cow survival.

Most farmers do not wish to have twins born on their farm because of the associated poorer survival rates. Psychologically, these cows stick in your mind. However, the same pertains with all cows experiencing poor transition management.

In conclusion, our late calvers have the potential to put profit in your dairy business and not to be considered as potential culls before the race begins!

Dr. Dan Ryan is a bovine reproductive physiologist and can be contacted at