|NADIS is a network of 40 veterinary practices and six veterinary colleges monitoring diseases of cattle, sheep and pigs in the UK.|
|NADIS data can highlight potential livestock disease and parasite incidences before they peak, providing a valuable early warning for the month ahead.|
|NADIS disease bulletins are written specifically for farmers, to increase awareness of prevalent conditions and promote disease prevention and control, in order to benefit animal health and welfare. Farmers are advised to discuss their individual farm circumstances with their veterinary surgeon.|
NADIS Cattle Report and Forecast – December 2006
The number of fertility reports fell further in November with all the main reproductive problems having fewer reports than average. The number of reports of non-detected oestrus (NDO) remained below average, confirming that the run of frequent reports seen during the summer had finished. However, missed heat remains by far the most commonly reported reproductive problem, accounting for over 15 times the number of reports as anoestrus. Indeed the NADIS data show that this ratio has increased significantly since 1998 when the ratio was around 12 (see Figure 1).
Figure 1: Graph showing the ratio of non-detect oestrus reports to anoestrus reports showing the slow rise since the start of NADIS.
Overall the number of NDO reports by NADIS vets has remained fairly consistent over the past nine years, with a moderate increase in reports occurring in the last few years. Oestrus detection thus remains a major problem that limits dairy farm profitability, and all research data suggests that detection rates are falling.
The reasons for this fall are complex, unquestionably production, nutrition and genetics are all important factors (compare the situation in New Zealand where the ratio of anoestrus cases to missed heats (defined as having a CL on the ovary) is 8:1 in favour of true anoestrus, completely the opposite of the UK), however reduced time for heat detection (with the associated reductions in staff skills) is undoubtedly the most important factor.
Do we need a new solution? Andrew Biggs in Devon reported that one of his herds had started using the Genus Reproductive Management and had seen significant improvements. This service provides a technician who regularly visits the herd to take responsibility for the heat detection and insemination.
The claims made by Genus certainly suggest that there are significant economic benefits to be made, it will be interesting to see if heat detectors become as common as foot trimmers currently are. Nine years ago when NADIS started foot trimmers were not a common sight, yet most large farms now use a foot trimmer regularly, and it is likely that increased use of foot trimmers is one of the reasons that veterinary lameness visits have reduced in the past few years.
It is highly likely that the trend for employing outside staff to undertake routine work on farm will accelerate, and there will definitely be money in it for the firm which spots the next opportunity.
After an October which had the highest number of anoestrus reports of any October since NADIS began, the prediction was that it would be a bad winter for anoestrus as energy deficiency problems at the start of winter were only likely to get worse.
However, the number of reports actually reduced in November to the lowest levels since November 2000. Any explanations for the sudden change would be gratefully received. Despite the fall, the next three months are likely to be associated with high levels of anoestrus so we need proactive action now to limit later disease.
Figure 2: Monthly figures for anoestrus reports by NADIS vets. The usual winter seemed to have begun early this year, but was followed by a marked fall in November.
Overall metabolic disease cases were 15% below average in November. Milk fever cases rose slightly but the cases reported so far this year remained lower than all years except for 2001.
The pronounced autumn peak in hypomagnesaemia continued into November, resulting in more grass staggers cases reported in autumn than during the spring turnout. Nevertheless, the numbers remained below the long-term average as they have all year. It would be interesting to hear thoughts on why the autumn peak was high this year – was it just the warm, wet weather?
Figure 3: Seasonality of hypomagnesaemia showing the very pronounced autumn peak seen this year.
The slow autumn fall in displaced abomasum cases continued in November in contrast to the usual rapid autumn drop. With one months left in the year it is clear that the continued rise in DA cases seen in every year since 2001 will not occur this year.
However the number of cases appears to have levelled out rather than fallen as there have been more DA reports this year than any year except 2004 and 2005. Have we reached a new plateau?
The NADIS figures show that housing cows is linked to high levels of sole ulcer and digital dermatitis, though for both of these diseases peak problems are seen at the end of the housing period.
In both cases cow comfort is an important factor. For digital dermatitis the contact time between slurry and feet is a major risk factor, so if cows are unable to use cubicles (or don’t want to) then digital dermatitis levels are likely to increase.
For sole ulcer, time spent standing rather than lying in cubicles is strongly linked to disease. With lameness control, perhaps more than any other disease, we need to look at the cows to identify the risk factors that we need to focus on. This was probably the major take home message of the recent ruminant lameness conference, cow behaviour is important wherever the cow is.
Figure 4: Sole ulcer cases showing the recent consistent rise in cases since August
After two months of above average reports there was a marked reduction in reports in November, a month when there is usually an obvious rise in cases. A warm wet October should have increased the risk. It will be interesting to see what happens in December.
Figure 5: Toxic mastitis figures showing the unexpected drop in November.
Despite modest increase in the number of reports in November both enzootic pneumonia and calf scours remained at levels below the long term average, although they were above last year’s very low figures. Calf scour outbreaks have now been below average since July 2005.
Is this just better management or reluctance to call out the vet to treat calf problems? The calf pneumonia data suggest that it’s at least partly the former as the number of pneumonia outbreaks reported has been around average for the same period. Comments are welcomed.
Figure 6: Calf scour figures showing the low number of reports for this year compared with the long-term average
Copyright © NADIS 2006 www.nadis.org.uk
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