Fertility improvements for impact
Strategic dairy farm host Andrew Gilman, from Statfold Farm, is improving his herd's fertility by using different data metrics to pinpoint the area where changes could have the most impact.
In August 2021, the fertility performance was not where Andrew wanted it to be. He met with vet James Breen to complete a structured review of factors affecting conception rate.
In this meeting, Andrew and James discussed methods to monitor current fertility performance, explored possible causes of poor conception rate, reviewed current management on Statfold Farm and suggested ideas to improve fertility performance.
Management on Statfold Farm
Dry cows are split into 2 groups: the dry cow period lasts 45 days and cows are brought into close group 3 weeks prior to calving. They are fed a full DCAB ration. Average days in milk is 230.
There are no issues with milk fever and very few DAs, metritis, retained placenta, etc. Andrew feels the system works ok but there are improvements to be made.
Once building work is completed, close to calving cows will be moving into new buildings which will hopefully address issues the old building creates, particularly feed space in transition, which is currently below a recommended target of 0.8m per cow.
After the cows calve, they are fed fresh cow drink, which they drink voluntarily. Usually get around 40 litres into the cow. Calves are drenched with tested colostrum and then moved within 24 hours into calf pens and cows enter the milking herd.
A new cubicle shed has been built for early lactation cows. Estimate ‘living space’ at 4.5m2 per cow – above and beyond the normal requirements for lying and feeding. Mid yield lactating group are milked 3 times a day. Late lactation group is milked twice a day.
Cows are fed twice a day using compact feeding: all dry ingredients of ration are put in feeder first, with 12kg water per cow, and mixed to create a wet ‘porridge’. This is left for a minimum of 6 hours, then 30 minutes prior to feeding, grass and maize is added. The ‘porridge’ coats the grass and maize meaning cows are unable to sort. The first mouthful of ration should be the same as the last.
Best of the best cows get bred to Holstein, while the worst are bred to beef. Middle ground ones are pro cross. Genomic test all calves and look to breed from the best heifers.
Methods to monitor current fertility performance
Using historic data such as calving interval does not help us make timely decisions or highlight which aspects of current fertility management may be going wrong.
What are better measures of today’s fertility management?
- 21-day fertility efficiency (also known as the 21-day “preg rate”) – this is the proportion of cows that could become pregnant in a 3-week period that do become pregnant
- Heat detection rate (% of all return serves which occur 18-24 days after a previous serve)
- First serve - when are we serving cows for the first time? How efficient are we at serving cows: is it 40 days or 100 days?
Statfold Farm - focus on fertility performance
Between November 2020 to January 2021, heat detection rate was 30%. From February to April 2021 this has increased by a third to 45% heat detection rate. 40% from an AYR high yielding cows is very good, 50% is extremely good.
On a fortnightly basis Andrew goes through all eligible cows and look at graphs on the computer. Also increased sensitivity. Give every cow every chance of bulling.
Measure the inputs – serves and PD data. How good is this herd at generating pregnant cows every 21 days? Commonly called the 21-day preg rate or 21-day fertility efficiency.
During the meeting we looked at data for Statfold for the 3 weeks ending 18 May 2021:
- 82 cows could have got pregnant
- 49 were served
- 9 PDs from those served
- 11% fertility efficiency – proportion of cows that become pregnant that could have
Potential issues with this – only a snapshot for those 3 weeks. Andrew regularly reviews this metric with his own veterinary surgeon, and the 21 day fertility efficiency has remained well below a target of 20%.
Conception rate - out of all the service events reported in a period of time, how many serves result in a PD+?
Conception rates are clearly a big issue for this farm, averaging 18%. Conception rate remains well below a target of 40%, averaging 18% in the last 12 months to August 2021 apart from a brief period in autumn 2020 that it reached 30%.
What factors were found to be affecting conception rate?
- First serve conception rates were very poor compared to return serves
- Semen/AI bulls – conception rates worse with certain bulls
- Impact of seasonality – time of year/season, day of the week – conception rates better in October and November, driven by first lactation heifers getting in calf
Other factors that can be involved are:
- Cow health – lameness, mastitis
- AI factors – AI operator/timing
- Association with days in milk and milk yield – worse with higher milk yield
- Ration and feeding – energy balance, feed space, micronutrients
These were not found to be a problem at Statfold Farm.
Overall, the 21 day fertility efficiency was poor because the conception rates were poor, caused by poor conception rates in the first serve cows. This was found to be due to issues with late dry cow management - feed space and energy balance around calving.
James's top tips for improving fertility
- Look at 21 day fertility efficiency with your vet or advisor and decide whether or not this is influenced more by heat detection rate or conception rate.
- If heat detection rate is below target, focus on increasing space for cows, improving foot health and methods of heat detection.
- If conception rates are low, focus on improving energy balance, feed space per cow (particularly in late dry period and early lactation, aiming for 0.8m per cow), ration presentation and AI factors such as bull used and AI operators.
Andrew's action points
- Aim: Improve first serve conception rate.
- Achieve the above by focusing on management of close to calving cows by moving cows into new building with increased feed space per cow, lower stocking density and more lying area.