Economic Impact of Disease

An animal suffering from any kind of pain does not produce in an optimal fashion. Speak-ing in economic terms, lameness causes decreased milk yield, reduced reproductive perform-ance, high culling rates and increased cost of veterinary intervention (HASSALL 1993;

VERMUNT and SMART 1994; COLLICK 1994; BERGSTEN 2001; MUELLING and LISCHER 2002).

The pressure of efficiency improvement is one of the major reasons for changes in man-agement, which can influence the incidence and prevalence of a number of diseases in dairy cattle (LOGUE 1997). The veterinary profession has recognized the poor state of information on economic impacts of food animal diseases for a long time; it was first mentioned by the National Academy of Sciences in 1966. The need for this kind of information is given be-cause it can be used to evaluate farm productivity and profitability and to design animal health programs (MILLER and DORN 1990). As the developed nations have gained control over the more devastating contagious diseases, diseases related to herd management have now become more evident (MILLER and DORN 1990).

Lameness in dairy cattle is currently ranked as the third most important disease affecting the UK dairy industry (after reduced fertility and mastitis) and continues to be one of the larg-est financial drains on the UK dairy industry (LOGUE 1997; OLSEN 1997;

O’CALLAGHAN 2002). In the UK, losses as a result of lameness in cattle are estimated to be

£30 per lame cow (WHITAKER et al. 1983); financial annual losses from lameness may amount to £1000 per 100 cows, and the loss to the dairy industry of the UK could be £15 mil-lion each year (GREENOUGH 1996). WARD (1999) reports the costs caused by lameness to be £43 million to 65 million, the costs of treatment £6 million to 51 million, and the costs of prevention £3 million to 5 million (WARD 1999). The National Animal Health Monitoring System (NAHMS), designed by the U.S. Department of Agriculture, estimated costs of dis-ease to be $172,40 per cow and year. Among these specific disdis-eases, lameness accounted for 5% (following mastitis (26%) and infertility (13%)). Considering the total preventive costs of

$20,88 per cow and year, drugs accounted for 52%, veterinary services for 33%, and producer labour for 15%. The largest component of preventive expenditure for lameness was foot trimming (MILLER and DORN 1990). In the Netherlands, lameness in adult dairy cattle is estimated to come in third place (after mastitis and reproductive failures) ranking diseases on

an economic scale; in Denmark, there is a loss of 38 Dutch guilders per lame cow and in Sweden net income per year increased with the increasing lifetime of the individual cow until at least the sixth lactation. (FRANKENA et al. 1992).

The costs of lameness depend on the type of lameness, its duration, and the age and stage of lactation of the cow. The direct costs to the dairyman comprise costs for treatment and ex-tra labour, reduced milk production, loss of body condition, a prolonged calving interval as a consequence of sub-optimal or even no oestrous expression, increased risk for teat lesions, and a higher culling risk together with reduced slaughter value (NOORDHUIZEN et al.

1996). Sole ulcers appearing in early or mid-lactation cost an average of £72 (direct costs) respectively £246 including the costs of reduced fertility and performance (KOSSAIBATI and ESSLEMONT 1999), GREENOUGH (1996) talks about £130-180 for a single case of sole ulcer; BERGSTEN (2001) mentions $650 for a single sole ulcer. Lameness due to digital dermatitis is estimated to cost £59 per case; one case of interdigital dermatitis might cost £55-100 (GREENOUGH 1996). On average, the costs of a case of lameness are calculated to be approximately £140 (KOSSAIBATI and ESSLEMONT 1999), if the lameness is treated promptly (O’CALLAGHAN 2002); AMSTUTZ (1985) estimated the average annual loss per lame cow to be approximately $200, KOSSAIBATI and ESSLEMONT (1995) calculated the total cost of a case of lameness to be at £250.

The causal relationship between disease and reproductive performance shows itself in loss of weight and body condition, and reduced milk yield and fertility (MCDERMOTT et al.

1994; similarly COLLICK et al. 1989; GROEHN et al. 1992; BERGSTEN 2001; WARNICK et al. 2001; HERNANDEZ et al. 2002). GROEHN at al. (1992) found that prolonged calving intervals, secondary mastitis and reduced milk quality cause additional losses due to lame-ness, which are economically important as well. MOSER and DIVERS’ herd-based case study (1987) reported a marked decrease in milk production, progressing to agalactia within about 30 days after the onset of lameness in improperly fed cows. WHITAKER et al. (1983) found that an average of 20% of the total lactation was lost from each affected cow. VER-MUNT and SMART (1994), too, found that 20% of the total lactation was lost from each af-fected cow. They state that costs for treating a lame cow are due to treatment, milk with-drawal and extra labour, decreased milk production, reproductive efficiency and bodyweight, and premature culling and replacement costs (VERMUNT and SMART 1994).

HERNAN-DEZ et al. (2002) reported a yield decrease of approximately 500 kg per lame cow. GREEN et al. (2002) found that lame cows not only undergo a decrease in milk yield, but that the yield reduction started four months prior to the onset of lameness and continued until five months after treatment; even a severely lame cow can produce about 30 litres of milk per day.

(GREEN et al. 2002; similarly BLOWEY 1998). Depending on the degree of lameness, milk yield decreases accordingly: the lamer a cow is, the lower the milk yield will be (HERNAN-DEZ et al. 2005).

Lameness appears to be a significant risk factor for culling throughout lactation. Cows that were treated for foot and leg problems at the beginning of the lactation had a risk of being culled that was six times higher than with sound cows. Cows treated for foot and leg problems during the second month of their lactation even had a twelve times higher risk of being culled during that month than did healthy cows (RAJALA-SCHULTZ and GROEHN 1999).

Chronic lameness is likely to reduce milk yield and fertility and predispose to early culling (WEBSTER 2002). Culling rates increase, and costs for herd replacement increase as well (OLSEN 1997; BERGSTEN 2001; O’CALLAGHAN 2002). In The Netherlands, for exam-ple, the average culling rate ranges from 16 to 33% per year. In about 68% of the cases, cull-ing is forced due to disease, 60% of which are made up by lameness and reproductive disor-ders. This means that on average 25 heifers per 100 cows are needed for herd replacement;

one heifer costs about $850 on total, which makes a total cost of $21.250 per year (NOORD-HUIZEN et al. 1984). COLLICK et al. (1989) found that 16% of all lame cows were culled;

KOSSAIBATI and ESSLEMONT (1995) showed that 5.6% of culls in 50 dairy herds in Eng-land in 1990-1992 were caused by lameness. A US study (ETHERINGTON et al. 1996) re-ported that lameness accounted for 10% of culls, while a French study found only 3% (SEE-GERS et al. 1998). In all cases, however, reproductive problems were major causes of culling, with lameness contributing indirectly (WARD 2001). Lameness in a herd means increased labour requirement, increased treatment costs, reduced milk production, reduced fertility, and involuntary culling and decreased slaughter value for the farmer (ALBAN et al. 1996; simi-larly VERMUNT and SMART 1994; GREENOUGH 1996; Ward 1999).