8 February 2008

7 minute read

Europe

CATTLE

Fertility

After a large rise in November the number of cattle seen for fertility problems decreased in December, primarily as the result of a small fall in the number of cows presented which had cycled but not been detected in heat. Except for April the number of missed heats reported this year was close to the long-term average. However the number of reports in April was one third of the long term average, resulting in the total number of reports of non-detected oestrus for 2007 being lower than all years except for 2000 and 2001 (Figure 1). This does not, as yet, appear to be part of a long term trend; the NADIS data suggest that there has been little change in the number of reports since 1997 with most years having an average of between 1200 and 1500 cases per month.

Figure 1: Change in mean monthly reports of non-detected oestrus

January to March is the peak season for missed heats. For many reasons housed cows show oestrus much less strongly and for shorter periods than cattle at pasture so it is essential that the effort put into oestrus detection is at a peak during this period. In the larger herds computer analysis can rapidly identify heat detection problems, allowing solutions to be developed before the costs get too high. We discussed last year the new service from Genus which provided a one-stop shop for heat detection and AI, we would be interested to hear of any reports of this scheme’s success. The other alternative to more and better heat detection is to dispense with heat detection altogether and use pharmaceutical control of the oestrous cycle as is done in many US herds. This has got so sophisticated that there are now pre-synchronisation programmes so that as cattle which are due to have a synchronised heat are synchronised before the programme starts. In this way you can end up with cows that have Presynch followed by Ovsynch and Cosynch. Such programmes are currently much less common in the UK but as herds get bigger and staff get fewer there is likely to be an increase of farms and their veterinary advisers looking at such programmes. We would be interested to hear whether there is any evidence of increased use of oestrus synchronisation.

The dramatic rise in the reports of ovarian cysts in November was followed by a return to average values in December. Overall the number of ovarian cyst reports was above the long-term average in 2007, resulting in the number of reports of non-detected oestrus per ovarian cyst being the lowest since 1997 (Figure 2). It appears that the trend towards missed heats being more common relative to cysts which developed between 1997 and 2002 has now been reversed.

Figure 2: Reports of non-detected oestrus / reports of ovarian cysts showing the steep fall in 2007

Metabolic disease

Overall metabolic disease cases were 45% below the long term average in December. This was reflected in the figures for the year; overall fewer cases of metabolic and nutritional disease were reported in 2007 than in any other year (even including 2001). The figures for the three classical metabolic diseases (milk fever, acetonaemia and grass staggers) were also lower than average this year, particularly milk fever and grass staggers the levels of which were just over half that seen in 1997.

The only metabolic disease where reports remained much higher than those seen in 1997 was displaced abomasum. However the trend was downwards even for displaced abomasum, with fewer reports for 2007 than in any year since 2002 (Figure 3). Clearly FMD may have played a role but reports from NADIS vets suggest that this decrease is real. Are we now getting better at controlling the disease?

Figure 3: Total numbers of reports of displaced abomasum showing the decrease in reports last year

Lameness

Veterinary involvement in lameness is decreasing. In 2007 NADIS vets treated almost half the number of lame cows which they treated in 1997. The fall has not been continuous but the trend is clear, with rises in case numbers compared to the previous year seen only in 2003 and 2004 (Figure 4)

Figure 4: Total number of NADIS reports for lameness using 1997 as a baseline showing the marked decrease in reports since that year

The decline in digital dermatitis reports is even more apparent for digital dermatitis, with 2007 reports only just above 30% of those seen in 1997. The NADIS data clearly show that digital dermatitis is no longer as important a veterinary problem as it was in the late ‘90s. Some of this reduction could be because farmers are happier to deal with digital dermatitis problems themselves; but recent research data suggest that digital dermatitis has decreased on UK farms and it’s likely that the NADIS data is reflecting this. The downwards trend for sole ulcer and white line disease is not quite as marked as that for digital dermatitis but it is faster than lameness overall, suggesting that lameness is becoming more complex in UK dairy cattle with diseases other than digital dermatitis, sole ulcer, white line disease and foul-in-the-foot accounting for a lower proportion of the cases and previously rare problems such as heel ulcer and axial disease becoming more prominent

Figure 5: Change with time in the number of reports per year of digital dermatitis, sole ulcer and white line disease using 1997 as the base year

A Gloucestershire vet post mortemed a chronically lame cow with a rib swelling, he has been following up these rib swellings for a while. The cow had several fractures of the cartilaginous portion of the rib at the point of greatest curvature of the chest. The vet suspects that trauma during lying down is the initiating cause. We would be interested to hear of similar problems. We have also had reports of spontaneous humeral fractures in four first lactation heifers in the same herd. Post mortem investigation should no evidence of trauma; there was no damage to either the musculature or the subcutaneous tissue except medial to the fracture site. Copper deficiency during the growing period is suspected as the underlying cause. Again we would be grateful for any information from a similar problem

Other diseases

Several NADIS vets reported problems associated with mouldy feed in December ranging from Bacillus licheniformis abortion to mycotoxins-associated scour. With the recent dramatic increases in feed prices for both concentrates and bought-in forage it may be tempting to use food of poorer quality in order to save money. This is very rarely a good idea!

CALVES

Calf pneumonia reports actually decreased in December compared to November which has only occurred twice before in the previous ten years. A Cumbria vet believes this may be a significant trend. He reported that he used to see most of his pneumonia cases between November and January but now he is seeing more problems at the beginning of the year. The low December figures mean that 2007 had the fewest reports of any year, even including 2001 where the destocking associated with the FMD outbreak resulted in a dramatic reduction in pneumonia cases. Some of the low figure may be due to the return of FMD, however 2007’s outbreak was much more restricted and did not affect any of the main livestock areas of the UK so 2007’s low figures are just part of the trend towards reduced veterinary involvement in calf diseases (figure 6)

Figure 6: Change with time in the number of reports per year of pneumonia outbreaks using 1997 as the base year

Although the overall number of reports of pneumonia were low we received several reports of pneumonia problems in vaccinated cattle. In some cases the cause of pneumonia was different from that vaccinated against. For example an Angus vet reported that one of his clients had problems in bought in calves that had been vaccinated with an intranasal IBR vaccine. He suspected an RSV problem particularly as home grown calves vaccinated against RSV were unaffected. Nutritional problems were also suspected.Anther Scottish vet reported pneumonia problems in a group of poor growing calves that had been vaccinated against the four major viruses and pasteurellosis. A post mortem examination suggested that Pasteurella multocida and Histophilus somni were responsible for the pneumonia, while further blood testing revealed that their copper status was marginal while both selenium and vitamin E concentrations were low. Investigation revealed that the farmer had not dosed the calves at castration as he had done in previous years

Further Reading

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