The use of databases to manage fertility.

Dairy farming now needs more records to be kept for quality assurance as well as for management. Herd fertility management is best brought about through the use of computerised records for each animal that integrate fertility, health and production. The development of dairy information systems over the last 25 years has allowed the creation of databases that give rise to "standards" of performance and "interference levels". These databases are of limited use for research unless the coding system has a structure and definition that works across herds. There is an increasing need to incorporate carefully coded disease records into these databases as there is increasing concern about welfare, zoonoses, assurance and the environment. Rules can be determined for satisfactory fertility so interference at an early stage is cost-effective. Integrated indices have been developed (using databases) that incorporate the costs of wastage caused by poor fertility, thus highlighting the priorities for management. Databases are best operated near to the farm, either in the veterinarian's office or on-line in the farm office. Databases can be made into expert systems that deliver high standards of fertility management. A checklist is included that can be followed to analyse the causes of poor fertility in a dairy herd.

Incidence of clinical mastitis in dairy herds in England.

The annual incidence of clinical mastitis was measured in 144 Holstein/Friesian dairy herds in England (average size 132 cows) during 1994, 1995 and 1996 by means of carefully defined mastitis indices. The mean annual incidence of the disease over the three-year period was 43.4 quarter-cases per 100 cows, and the disease affected 25.9 per cent of the cows in the herds, with 1.6 quarter-cases per affected cow. In terms of cow-cases, the mean incidence was 39.9 cases per 100 cows in the herd and hence the ratio of quarter-cases to cow-cases was on average 1:1. The proportion of repeat quarter-cases was on average 19.4 per cent, and the recurrence rate was 18.3 per cent. The new infection rate was 28.3 per cent.

The costs of production diseases in dairy herds in England.

Economic losses due to common health problems in dairy cattle were investigated in 90 Friesian/Holstein herds (average size 152 cows), which calved in England during the 1992/1993 season with an average annual yield of about 6000 l per cow. By using only the direct costs of common production diseases and other health problems (mastitis, lameness, vulval discharge, treatments for oestrus-not-observed, retained foetal membranes, milk fever, twinning, calf mortality and aid at calving), the cost of ill health in a 100 cow herd with average rates of these problems (compared with target levels) was estimated at Pounds 6300 per year. The costs ranged from Pounds 1200 (average of the top 10%) to Pounds 13600 (average of the worst 10% of the herds). The main losses were due to mastitis and lameness (38 and 27% of health cost, respectively).

Culling in 50 dairy herds in England.

A survey of 50 Friesian/Holstein dairy herds (average size 178 cows) in England investigated the rate of culling and the reasons for disposal and death over three years from 1990 to 1992. The average total annual culling rate was 23.8 per cent (22.0 per cent sold and 1.8 per cent died). Of the disposals, 54 per cent were culled by the end of their fourth lactation. Poor fertility was the most important reason for culling (36.5 per cent of disposals), followed by management policy (11.5 per cent), mastitis (10.1 per cent), bovine spongiform encephalopathy (BSE) (7.4 per cent) and lameness (5.6 per cent). The most common causes of death were mastitis (8.9 per cent) and BSE (11.5 per cent), but 46 per cent died for unknown reasons.

Incidence of production diseases and other health problems in a group of dairy herds in England.

The incidence of major production diseases and other health problems was investigated in 90 Friesian/Holstein dairy herds in England (average size 152 cows) for cows calving during 12 months in 1992-1993. The mean incidence of mastitis was 33.2 cases per 100 cows, and it affected 20.6 per cent of the herd with 1.6 cases for each affected cow. On average, 17.4 per cent of the cows suffered from lameness, with 1.4 cases per affected cow and a total of 24.0 cases per 100 cows. Cows treated for oestrus-not-observed totalled 33.6 per cent, with 46.4 treatments per 100 cows. The incidence of milk fever was 7.7 cases per 100 cows. Retained fetal membranes affected 3.6 per cent of cows. Vulval discharge affected 15 per cent of the average herd with 1.4 treatments per affected cow and a total of 21.2 treatments per 100 cows. The mean incidence of twinning was 4.1 per cent. Calf mortality claimed 7.8 calves per 100 calves born. The average number of cows given aid at calving was 8.7 per 100 cows calving.

Recurrence odds ratios for periparturient diseases and reproductive traits of dairy cows.

The recurrence odds ratios were calculated for a number of periparturient diseases and reproductive traits from 1490 pairs of successive lactations in dairy cattle. Vulval discharge, oestrus not observed and mastitis diagnosed before service had summary recurrence ratios of 1.39, 1.37 and 1.49 respectively, all statistically significant at the 5% level. Retained foetal membranes and calf mortality had higher summary risk ratios of 1.84 and 1.76 respectively, but were not significant at the 5% level. Whilst the number of services per conception did have a recurrence ratio above 1, the result was not significant at the 5% level.

Inter-relationships of periparturient diseases in dairy cows.

The associations between periparturient diseases in 3603 lactations over three calving seasons were assessed on 10 dairy farms in the south west of England by using logistic regression. Calf mortality and dystocia were strongly associated. Twinning and dystocia were important predictors of calf mortality. Twinning was also a significant predictor for retained fetal membranes. Retained fetal membranes, twins, calf mortality and dystocia, in that order of importance, were risk factors for vulval discharge. Twinning, dystocia, retained fetal membranes and lameness before service increased the risk of mastitis before service. Similarly, mastitis and dystocia before service increased the risk of lameness before service. Oestrus was less likely to be observed in cows that had twinned or suffered lameness before service, the latter having a significantly greater influence in first calvers than older cows.

The scope for raising margins in dairy herds by improving fertility and health.

Under today's difficult farming conditions, the farmer must examine every aspect of management that may improve economic efficiency. Apart from the usual areas such as feeding and the use of variable and fixed costs, there is scope in terms of improving health and fertility of the cattle in the herd. This is particularly so at the present time, as the standards of such performance are generally low. The main losses occur in animals with endometritis, lameness, mastitis, extended calving intervals and excessive involuntary culling. The cost in a 100 cow herd of carrying average rates, rather than practically attainable target rates, is around 10,000 pounds per year. By only using the direct costs of disease and by including indirect costs separately, as measured by whole herd fertility indices, double counting has been avoided.

Relationship between herd calving to conception interval and culling rate for failure to conceive.

The factors affecting herd calving to conception intervals and culling rate are the interval to first service, the efficiency of heat detection, the pregnancy rate and the maximum number of oestrous cycles allowed to occur before the cow is considered to be so far into lactation that even if it does conceive, the length of the dry period and the delay to the next calving will make its production uneconomic. Depending on the fertility factor (the product of the average herd pregnancy rate and the oestrus detection rate) it is the maximum number of oestrous cycles, usually dictated by the length of the calving interval desired, that decides the outcome. A graphical representation of these mathematical relationships demonstrates methods for achieving different economic and other objectives.

A decision support system using milk progesterone tests to improve fertility in commercial dairy herds.

MOIRA (the Management of Insemination through Routine Analysis) is a computer program that is a module of DAISY, the Dairy Information System. This decision support system uses the results of milk progesterone tests to determine when to inseminate cows. The MOIRA program plans a series of weekly tests for each cow, to check for cyclicity. Subsequently, the program lists cows for alternate day tests to identify the days when they should be served, and if necessary, a cow can be served without being seen in heat. The work which led to the development of MOIRA showed that ovulation detection rates of 98 per cent were achieved; in commercial herds the rate is around 85 per cent. As pregnancy rates were unchanged, the effect of MOIRA was to reduce calving to conception interval from 90 to 85 days and the culling rate for failure to conceive from 13 per cent to 5 per cent in one herd and from 104 to 100 days and 21 per cent to 12 per cent in another herd. The use of the program produced an estimated extra net profit for the farmers of pounds 52/cow in the first herd and pounds 54/cow in the second.

Measuring dairy herd fertility.

The use of the calving index as a measure of herd fertility ignores the proportion of the herd that is culled, generally for failing to conceive. It is more important to consider the total cost of long calving intervals, high culling rate and even low pregnancy rates in an integrated index that reflects inefficient management, than to have to cope with balancing a number of separate physical indicators. In a study of 91 herds containing 14,524 cows a full range of physical indices was examined. The average herd calving interval was 380.3 days, with a culling rate of 23.1 per cent. Of the cows calving, 76.9 per cent recalved, a figure which when adjusted for the calving interval (CIA calving rate) became 73.8 per cent. In quartiles split on the basis of CIA calving rate, the top quartile achieved 82 per cent with a calving index of 375.2, and a culling rate of 16.7 per cent. These standards were achieved by serving 91.9 per cent of the cows after calving, at an interval to first service of 67.2 days. The submission rate for artificial insemination in the first 24 days after the earliest service date was 57.5 per cent and the overall pregnancy rate was 51.2 per cent. As a result 92.1 per cent of the cows served, and 85.3 per cent of those which calved, conceived again, with an average of 1.9 services per conception. Assessing fertility on a financial basis, with costs attributed to calving interval, culling rate and pregnancy rate to give a fertility index, the average herd was losing pounds 62/cow/year, compared with target levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Survey of the operation of dairy herd health schemes by veterinary practices in the United Kingdom.

A postal survey of 566 veterinary practices with dairy farms among their clients showed that the majority of the practices were very positive about the benefits of running a herd health scheme. Nevertheless, only a third of them were running a scheme, and most had attracted only a small number of clients. The size of the practice (in terms of the number of veterinarians and the number of dairy farming clients) was the most significant factor determining whether a practice was likely to run a herd health scheme, and the age of the veterinarians did not appear to have any affect.

Oestrous behaviour in a herd of dairy cows.

A group of 60 housed Friesian cows were observed continuously for a period of 25 days, during which time all cows were recorded for incidence of mounting activity and 18 selected cows were recorded for various aspects of maintenance activity. All 60 cows were judged as showing oestrus. Average duration of oestrus (+/-SD) in 33 cows was 14-9 +/- 4-7 hours, and the cows were mounted 56-3 +/- 34-8 times. The greatest mounting activity was associated with the night hours. There was no diurnal pattern of onset of oestrus. The majority of mounting activity (79 per cent) occurred in the cubicle area of the building. Comparison of maintenance activities showed that oestrous cows spent, on average, less time standing in a cubicle (P less than 0-01), lying in a cubicle (P less than 0-001) and more time standing elsewhere (P less than 0-001) than non-oestrous cows. The results are discussed in relation to oestrus detection.