14 September 2001

MANAGEBODYCONDITION, IMPROVECOWFERTILITY

Improving dairy cow fertility

by managing body condition

is one topic being tackled

by the DEFRA-funded

Livestock Knowledge

Transfer project.

Richard Allison reports

from one producer

already putting the

technique into practice

MAINTAINING dairy cows at their target body condition score is crucial for achieving high pregnancy rates and avoiding related problems, such as displaced abomasums and retained cleansings.

To achieve this, cows must be scored for body condition throughout their whole lactation cycle, says Cheshire producer Philip Latham. "Monitoring body condition for only part of their lactation does not allow time for any condition adjustments to be made before drying off.

"All cows are scored at calving, drying off and monthly during their first three months of lactation. Scoring is easy and quick to perform and does not require any special facilities."

He aims for a body condition of three at calving and drying off, and to minimise losses during early lactation. However, Mr Latham stresses that his score of three is for a heavy cow. Most producers would consider the target score to be nearer 3.5.

"It is a subjective scoring system, but useful in highlighting any change in body condition against your target. At Brook House Farm, the same person does all the body scoring to minimise operator variability."

Mr Latham has developed his own scoring system based on the extent of fat and muscle cover over four areas of the body; the transverse processes, the loin area, upper parts of the back legs and the tail head.

"The tail head is the least important area. Unlike Friesians, Holsteins will never really fill out the tail head area. Remember that cows are like people and come in all shapes and sizes."

Mr Latham was initially sceptical about being able to improve fertility through better nutrition and minimising changes in body condition and periods of negative energy balance. However, data collected from more than 700 calvings on the farm clearly show the negative effect of weight loss on fertility.

"After adopting the system, pregnancy rates to first service were increased from 42% to 58% within one lactation. Pregnancy rates topped 63% the following year, but have slipped back recently," he says.

This recent blip was found to be due to feeding insufficient forage, resulting in less acetate being produced by rumen microbes. Acetate is needed by the cow for production of fertility hormones.

Mr Latham now believes most fertility problems blamed on poor heat detection are actually caused by unbalanced nutrition, which may or may not cause body condition loss. Cows fed sub-optimally may not show the full signs of bulling, he explains.

In addition, weight loss can reduce egg quality. It is, therefore, essential to pay extra attention to nutrition and body condition after calving when weight loss often occurs. This is because the egg for fertilisation, when serving cows 60 days post calving, will have been developing during this period of weight loss.

One problem previously encountered by Mr Latham was cows with twin calves losing excess body condition during the dry period to maintain calf growth. This resulted in lower dry matter intakes, cows calving too thin and being harder to get back in calf due to a severe negative energy balance.

Losing too much body condition between drying off and calving also results in more cases of retained cleansing and endometritis (whites). Cow with twins are now identified by ultrasound scanning at PD and kept in a separate close up group to allow higher energy diets to be fed, says Mr Latham.

"Over-fat cows at calving will also have impaired fertility. This is because dry matter intake is lower, so cows cannot consume sufficient energy to maintain milk output during early lactation," he adds. &#42

Further details and fact sheets are available from the Livestock Knowledge Transfer project stand at the European Dairy Event. Mr Latham and Prof Bridget Drew will also present seminars on the day.

BODY CONDITIONS

&#8226 Score cows regularly.

&#8226 Minimise condition loss.

&#8226 Avoid over-fat cows at calving.

Above: Cows scoring 1.5 are too thin and at risk from fertility problems.

Left: All cows are scored at calving, drying off and monthly during their first three months of lactation, says Philip Latham.