19 November 1999

Progesterone test puts end to guesswork

Progesterone profiling has

been around for over 20

years and its high time

producers were able to put it

into practice on their farms

to improve fertility, believes

one Lincs producer.

Marianne Curtis reports

YOU didnt see her bulling; its the Holstein genetics; high yields and good fertility dont go together; its the vets fault… sound familiar?

True, dairy cow fertility is declining at a rate of 1% a year, but blaming someone else does not help. Progesterone testing is the only way to get an inside look at how your cows biological clocks are ticking, believes one Lincs producer.

Frequently called upon to take part in Nottingham University dairy cow fertility studies, John Lamming of Grange Farm, Middle Rasen, is convinced of the benefits and is keen to make the technique more accessible to other commercial producers.

"The technology for progesterone testing has been with us for more than 20 years, but until powerful computers became available for record keeping, it was not easy for producers to keep track of an individual cows information." When Mr Lamming is doing trial work for Nottingham University, it carries out progesterone analyses on milk from his cows, and he has access to the results. But at other times he uses on-farm kits, which cost about £10 a cow.

Until 18 months ago trials on the 112-cow herd, which calves all year round, meant taking three milk samples a week from each cow from a week after calving until she was in-calf. Samples were posted to the university once a week, and results faxed back within three to four days.

Mr Lamming explains how progesterone results are interpreted. "Each cow has her own progesterone profile. After calving, progesterone levels remain flat for a number of days at about 2ng/ml. Once levels begin to rise above 3ng/ml this indicates that the cow is starting to cycle.

"At bulling, progesterone levels fall to zero. By five days after bulling they will rise above 3ng/ml, then continue to rise dramatically until 19 days after bulling when they start dropping again before the next heat."

Keeping a record of cows progesterone profiles means accurate heat detection without the need to stand and watch cows for the recommended 20 minutes three times a day. "During the two or three years we were progesterone profiling, we only missed two heats in the whole herd. The tests mean you can make sure a cow is cycling correctly before serving her. Also, some cows show little sign of being on heat. I have served cows successfully that have only sniffed another cow based on progesterone levels falling from above 5ng/ml to zero."

Heat detection improvement in the herd is reflected in conception rates and calving interval. "At the start of the programme, the service to conception ratio was 1.7. At the end it had fallen to 1.48. Calving interval decreased from 379 days at the start to 358 days at the end."

Not all cows have the same breeding cycles, and Mr Lamming believes some of the variation is genetic. "We had a mother and her two daughters in the herd that were slow to start cycling after calving. Most cows start cycling 30-35 days after calving and are first served around day 50 to allow time for a repeat service around day 80, if necessary. The mother and two daughters did not start cycling until day 80."

Abnormal cycles – which become apparent when cows are progesterone profiled – can also cause breeding problems and based on Nottingham University findings, Mr Lamming believes that 10% of all cows should not be used to breed replacements.

"I know the poor breeding families in my herd and have culled five animals for this reason. I have also stopped breeding replacements from one family. Female fertility traits are heritable, about half as heritable as milk yield. Semen companies should provide information on fertility traits by collecting progesterone profile information from bull mothers and daughters."

But genetics is not the whole story and progesterone profiling can also help producers keep a check on the effects of management changes on fertility, says Mr Lamming. "We were having a problem getting some first calved heifers back in-calf. Some of the group were housed three weeks before calving whereas others did not come in until just before calving.

"In the group that came in just before calving, progesterone profiles showed that they took an average of 15 days longer to start cycling than those brought in three weeks before." This led to Mr Lamming housing all heifers earlier, and resulting improvements in fertility.

Disease

The technique can also help indicate when disease, rather than poor heat detection is the problem. "Several years ago we had cows returning 12 weeks after insemination. I was sure they had been in-calf but the vet said we had missed three heats.

"When we began profiling, I could prove that the cows had been in-calf. The problem turned out to be lepto, causing embryo mortality. We vaccinate against the disease now," adds Mr Lamming.

While progesterone profiling can provide a lot of clues to the causes of infertility, he realises that simplification is needed if the technique is to be adopted more widely. Future work with Nottingham University will work out the minimum number of tests needed to get results.

A computer program being developed at the university will ask producers questions such as: When do you want this cow to calve again? Based on the answer, the programme will prompt producers to test cows or look out for them bulling at particular times. &#42

PROGESTERONE TESTING

&#8226 Pinpoints fertility problems.

&#8226 Detects poor breeders.

&#8226 Becoming more accessible?