INCREASING FERTILITY
Lower FTC rates to reduce lost income
CUTTING failure to conceive (FTC) culling rate may mean longer calving intervals, but will reduce lost income on many dairy units suffering from the declining fertility of the national herd.
According to Dick Esslemont, from the University of Reading, there is a serious trend of reduced fertility in UK dairy herds, which is causing economic loss.
Speaking at an MDC conference in Staffs, he said analysis of 52 Holstein Friesian herds, recording fertility performance through the Dairy Information System (DAISY) showed an increase in infertility over the past 11 seasons (see table).
To assess the cost of infertility in the DAISY herds studied, Dr Esslemont and co-worker, Mohammad Kossaibati, used the Fertility Economic Index (FERTEX). This calculates lost profit/100 cows, taking into account costs of extended calving interval, increased number of services/conception and FTC culling rate.
"Average FERTEX score shows lost profits have increased from about £2000 in 1987/88 season to over £6700 in 1997/8, with an overall average of about £4200/100 cows."
With cull cows estimated to cost producers about £600 each, compared with £2 a day for increased calving interval, Dr Esslemont believed that farmers needed to concentrate on reducing FTC culling rates to below 7%.
Top performing herds in the study were those calving cows for six months or more, yet had lower culling rates, he added.
"Keeping to a strict calving pattern, for reasons such as grass availability and seasonality payments on milk, means cows are under pressure to conceive. The number of oestrus cycles available for each cow to become pregnant can be as low as three for late calvers," he said.
Aiming for a voluntary waiting period of 50 days before first service, for cows not restricted to a tight calving pattern, meant they had eight active oestrus cycles to become pregnant, when the farmer was persistent.
More efficient heat detection would allow producers to improve pregnancy rates, said Dr Esslemont. "Because of increased yields, many cows have abnormal oestrus cycles or do not show signs of heat, and less labour means limited time is spent detecting heat cycles."
The optimum time for service was 12-18 hours after the cow has first stood to be mounted, so records must be kept for accurate timing of mating. When labour was short, then milk progesterone testing, tail paint or kamar heat detectors could be effectively used to detect heat, he said.
Although pregnancy rates could be influenced by many factors, such as feeding, health, age and milk yield, Dr Esslemont emphasised the importance of checking bull fertility.
"About 20% of available bull semen is hopelessly infertile and AI figures for effectiveness are difficult to get hold of from suppliers. On-farm bulls should also be checked for fertility."
When DIY AI was used, skills of the inseminator and upkeep of equipment should also reviewed, he added. *
INCREASING FERTILITY
• Reduce FTC culling rate.
• More efficient heat detection.
• Check bull fertility.
Concentrate on reducing FTC culling rates to below 7%, says Dick Esslemont.
Average trends in fertility – DAISY
93/94 season 97/98 season Target results
% served of cows calved 90.3 88.6 93.1
Calving to first service (days) 70.6 76.3 64.1
% return heat detection rate – 50.4 64.3
% all service pregnancy rate 45.6 42.5 56.1
Number of services/conception 2.18 2.36 1.74
% conceived of those served 88.1 86.2 93.5
Calving interval (days) 383.4 390.2 370.9
% FTC culling rate – 11.5 6.5
FERTEX (lost profit/100 cows) -4,135 -6,718 202