News & Advice

How tight is your calving pattern?

Sep 7, 2017 | Dairy, Dairy Farm Reproduction, Farm systems

Steve Harkness, Veterinarian, Anexa FVC Gordonton

Days in milk is one of the biggest drivers of production and a tight calving pattern is one of the key influencers of your reproductive performance. Can you afford to let your calving pattern slide? 
Submission rate is the biggest driver of your reproductive performance, therefore focussing on hitting a 90% 3-week submission rate is not negotiable if you want to achieve good performance. The national average 3-week submission rate is only 80% which goes a long way to explaining why we are not hitting the national targets for reproductive performance. All herds that ARE hitting the target have achieved a 3-week submission rate of at least 90%. 
Non-cyclers are one of the biggest causes of poor submission rates. 
Therefore,  the first step  is identifying whether non-cyclers are going to reduce your submission rate. To do this we need to know how many you have. To identify the non-cycler group, we recommend tail painting cows five weeks before the planned start of mating (PSM). This gives us enough time for a complete cycle plus time to initiate treatment before the start of mating if required. Cows are suitable for non-cycling treatment once they have been calved for just three weeks. 
We recommend that if 85% of whole herd (including late calvers) has cycled before PSM then the herd is on track to achieve at least a 90% submission rate without any intervention. However, if you have not reached this target, then the only option to improve your submission rate is to treat the non-cyclers. 
Treating non-cyclers is treating a herd problem (low submission rate) by synchronising a group of cows (non-cyclers). These cows are not cycling because they calved late, were below optimal BCS at calving, were poorly grown as heifers, had mineral deficiencies, lost excessive condition score after calving etc. There is only a small chance that genetics are contributing to the problem and that is mostly to do with the breed of the cow i.e. Friesians are more likely than crossbreds to be non-cycling. 
The  second step  is identifying the best method to deal with your non-cyclers. 
Our Vets can step through a return on investment calculator with you. This is based on trials in this area and can be modified to reflect the conditions on your farm. It covers different treatment options and timing of treatments. 
CIDR programmes are nine days in length and treating cows nine days before the PSM will give you the best return on your investment. Cows starting treatment before the start of mating will on average calve 16 days earlier than if they had no CIDR. This advantage is increased, on average, by a further three days when the optional extra eCG injection (fertility enhancement) is added to the program. Typically, extra AB calves are born the following year and treated cows are less likely to be non-cyclers the following season. 
There are limited other options for attempting to encourage the commencement of cycling in non-cycling cows. A commonly used strategy is Once A Day milking (OAD). However, research shows that cows that are on OAD for 4 weeks from 7 days before the PSM until the end of week 3 of mating had no improvement in conception rate and an increase in 3-week submission rate of only 11%. Moreover, the milk production loss in this group would not cover the cost of the intervention response. If you want to use OAD to help improve the pre-mating cycling rate in your herd then the strategy needs to be implemented from much earlier in the season, which is well before you know if you have a cycling problem! Therefore, this becomes a bigger farm systems decision, rather than a knee-jerk reaction to a non-cycler problem. 
Several trials in dairy cows have looked at whether running bulls with the non-cyclers will get them cycling quicker. The results show no improvement in cycling rate, but as bulls can potentially detect cycling cows better than some people, the strategy may be effective in herd’s where the pre-mating cycling rate and submission rate are low due to missed heats. 
Catch up with your Vet during September – book your repro ready now. 

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