NON-CYCLER TREATMENTS
CIDR/DIBs:
Is it worth treating non-cycling cows? New Zealand research shows that treating non-cyclers with CIDRs/DIBs prior to the planned start of mating, PSM (e.g. on day -10) advances their average calving date by 19 days compared to no treatment. This means an average extra 19 days in milk (that’s an extra 27kg milk solids at 1.6kg/day) for the following season for every cow treated and a healthy return on investment. Other advantages are: more AB heifer calves, a tighter calving spread and fewer non-cyclers needing treatment next year (as they’ll calve earlier and have more time to start cycling next year). Non-cyclers are typically later calving cows or those in energy deficiency rather than ‘poor breeders’, so treating them does not breed for infertility.
The return on investment for CIDR treatment is realised in the following lactation, so we need to consider the expected 2021/2022 season pay-out. But even using a lower expected pay-out, we can demonstrate that when the cost of extra feed and treatment are accounted for, non-cycling cow treatment is still profitable. Blanket CIDR treatment prior to PSM is the gold standard non-cycler treatment.
Ovary scanning and CIDR/DIB/OvSynch/PG programmes:
Whilst blanket non-cycler CIDR treatments are the gold standard, there is a place for using alternative programmes like Ovsynch/PG. This method allows for a more individualized cow approach, based on ovary scanning. Generally, the treatment regime across the non-cyclers is split up into CIDR, Ovsynch or PG depending on what is found on the ovaries at scanning. There are certain advantages of this method – e.g. also finding abnormalities on the ovaries such as cysts, pyometras (infected uterus), lower costs, but conception rates overall will be lower than with blanket CIDRs. However, in calf rates will definitely be higher than leaving non-cyclers untreated!
Other alternative options that you may have heard of for ‘treating’ non-cyclers are discussed below.
Once-a-day milking (OAD).
On some farms, OAD milking can improve cow condition and fertility, but this can come at the cost of milk production. A DairyNZ study showed that OAD milking for either three or six weeks at the start of lactation temporarily improved cow condition but had no effect on the number of non-cycling cows or any of the fertility measures. When milking OAD for ten weeks from calving, they found cows started cycling seven days earlier and required fewer CIDRs than those milked TAD. However, OAD milking for over 3 weeks has a sustained milk production loss over the season.
Separation and preferential feeding of non-cycling cows.
A New Zealand study demonstrated that separating non-cyclers out 7 days before planned start of mating and feeding them more actually decreases their first service conception rate and 28-day pregnancy rate. This is mainly due to the disruption of their social structure and less involvement in sexually active groups, which makes heat detection more difficult.
Use of entire or vasectomised (teaser) bulls.
No studies have been able to show a reproductive benefit from using bulls to get cows cycling. They are excellent heat detectors so may have a place in a reproduction plan, but that place is not with the non-cyclers.
Waiting until the end of the first round.
Delaying treatment until the end of the first round means you have fewer non-cyclers to treat. But at least 31 days of mating have passed by the time non-cycling cows get inseminated for the first time, meaning the average conception date does not get advanced to the same degree as treating prior to planned start of mating. Delaying treatment to the 2nd round costs less up front but is less economical in the long term than treating early. This has been proven in NZ based trials that show treating non-cyclers prior to PSM produces 8 x more milk than treating cows after the first round.
The best practice with non-cycling cows is prevention! However, if you have non-cyclers, evidence shows that blanket CIDR treatment BEFORE PSM is the most effective option. This buys you an average of 19 days extra milk for every cow you treat next season and improves your calving spread. There are also other options available, e.g. ovary scanning, with a lower cost input.
Please have a chat with your primary vet at your pre-mating consult to discuss the various options available, and we can see what’s best for your farm.