4 August 1995

CAN BE DEAD EXPENSIVE

OVER-CULL

Is the lifeline of your herd too short? According to Reading University it is. Jessica Buss reports

DAIRY herd culls are costing milk producers an average of £5000 a year in lost profit, claims Dr Dick Esslemont, head of the DAISY Information Service at the University of Reading.

A survey of three years culling records taken from 50 dairy herds reveals the top 25% of herds cull 17% of the cows each year compared with an average of 24%.

"The cost of the extra 6.6% of culls is £5000 a year for an average 100-cow herd due to the cost of rearing or buying replacements, and losses in milk yield and calf value," he says.

The bottom 25% of herds cull 29% – almost one third of the herd each year, and twice the number of cows as the top 25%. Dr Esslemont claims this reduces profit by £9000 a year for an average herd.

He says many producers are trying to improve margins but continue to lose money by unnecessary culling.

"This is where profit is lost, but as it is unearned income it is not shown on the farm accounts," he says.

Dr Mohammad Kossaibati, who completed the studies, believes the lifetime of the British herd is too short, with 41% of dairy cows culled by their third lactation.

"A lot of young animals are being lost unnecessarily, with over half the cows sold by their fourth lactation," he claims.

The two main reasons for culling are infertility and disease. These account for 65% of all culls, many of which could be avoided, says Dr Kossaibati.

"Infertility is the greatest single reason given for culling, amounting to a third of the total recorded culls each year," he says.

Dr Esslemont adds that infertility problems are within the producers control. According to statistics from DAISY-registered herds, the average pregnancy rate in dairy herds is below 50%, but the top 25% of herds achieve a pregnancy rate of 63%.

"Poor fertility results are due to inadequate recording or a lack of interpretation of available data," says Dr Esslemont. "Good herd management can reduce culls due to infertility to less than 7% of the herd, particularly heat detection rate and inseminating the cow at the correct time."

He claims it is possible to achieve pregnancy rates of 70%. Although this is rarely achieved, 60% is a realistic target for dairy herds.

According to Dr Kossaibati, diseases are responsible for a further third of culls. These can be identified as non-infectious and infectious. Non-infectious diseases such as BSE, metabolic and digestive disorders and lameness account for 16.7% of culls.

"Lameness could be reduced, as it is often a result of injury or accident due to poor housing," says Dr Kossaibati.

Mastitis is still the biggest cause of culling for infectious disease. The numbers of cows culled because of mastitis has not reduced from previous studies even after all the research of recent years, he says.

He stresses the need to record the reasons for culling. Of the cows culled each year, 8% die on the farm from disease. But for 46% of the total number of deaths, the reason is unrecorded or unknown.

"It is important to find out why these animals are dying in order to prevent further cases, and for good animal welfare," he says.