Knowing the cost of common diseases can help dairy farmers and their veterinarians plan treatment and prevention strategies that are likely to improve the profitability of the dairy.
Knowing the cost of common diseases can help dairy farmers and their veterinarians plan treatment and prevention strategies that are likely to improve the profitability of the dairy. If the cost of the problem and the components of that cost are known, it is easier to judge whether allocation of resources can be expected to reduce that cost and return a net profit. Rarely are complete data available from a farm to permit calculation of overall disease costs. This paper evaluates data from published reports, the authors' veterinary practice, and estimates when no data was found for the factors that contribute to the overall cost of common diseases of adult dairy cattle.
Milk fever, dystocia, retained placenta/metritis, ketosis, left displacement of the abomasum, clinical mastitis, and lameness were chosen since they represent the majority of the clinical conditions of dairy cows. The author recognizes that many of these diseases have nutritional, environmental, or management policy components as inherent risk factors. These are the things that are most amenable to change. The author further acknowledge that there are complex interrelationships among the disease entities discussed in this report even though they will be ignored during this analysis.
Sources of information for this report were chosen to reflect as closely as possible the current situation on medium to large commercial dairies. Hence, data from some recent surveys and epidemiological studies were excluded since the herd base from which the data derived was judged too dissimilar from typical commercial dairies. Some estimates from published works were modified with information from our up-to-date herd files (Dairy Comp 305) representing about 11000 milking cows in large herds in the vicinity of Ithaca, New York. The intent of this analysis is to make the information relevant to veterinarians, consultants, and managers particularly those serving large free-stall herds. Prices for dairy cattle, milk, feed, and labor used in the report were current in central New York in spring 2008.
Disease definitions were 1) milk fever (MF): abnormal behavior or weakness requiring treatment with calcium from 2 days before to 5 days after calving. 2) Dystocia (DYS): calving that requires assistance. 3) Retained placenta/metritis (RP): failure to expel the placenta within 24 h of calving or metritis characterized by malodorous uterine discharge, fever, and inappetance. 4) Ketosis (KET): reduced appetitie accompanied by ketonuria in the first 5 weeks of lactation. 5) Clinical mastitis (MAST): grossly abnormal milk with or without systemic illness. 6) Left displacement of the abomasum (LDA): abomasum displaced dorsally and to the left of the rumen diagnosed by simultaneous auscultation and percussion. 7) Lameness (LAME): Limping or reluctance to move due to painful conditions of the digit(s).
Diseases cost producers through direct effects in extra labor for treatment, veterinary fees, and drugs. Treatments may require discarding milk due to drug residue. Diseased cows may produce less milk than expected due to reduced feed consumption resulting in indirect costs through lost potential income. Diseases occurring early in lactation may lead to delayed conception. Cows may be culled directly or indirectly as a consequence of disease (via low milk production or delayed conception) and some cows die of the diseases being considered.
Replacement of dead cows was assigned a cost of $2200. Cows that are culled involuntarily were given a slaughter value of $.45/lb liveweight and an average weight of 1350 lb for a selling price of $600. Replacement heifers were valued at $2200 so a replacement costs $1600. This replacement cost is based on current cash accounting method and does not offset the cost of the replacement with her future income potential. A better method of calculation might consider the net present value of the sick cow had she not become diseased and her current value as a marketable cull. The result of our method is probably an overestimation of the cost of culling but does capture the upper limit of this cost and was chosen for the convenience of calculation. Veterinary fees were taken from published reports or estimated from a $20 stop charge and $100 /h. The entire veterinary visit was assumed to be for treatment of the single sick cow considered in the analyses. Veterinary costs are reported as time or professional fees and do not include medications. Out of hours fees for emergency care typically carries a surcharge of about $25. These assumptions for veterinary fees will result in overestimation of the likely actual costs for veterinary services but represent a reasonable upper limit. Drug costs for treatment of specific diseases was not available for most diseases under consideration. Typical costs for the medications required were estimated from the retail value of the appropriate drugs from national distributors or from our pharmacy. Labor costs for treatment of sick cows were calculated from estimates of the extra time required to perform the tasks of segregation, restraint, and therapy. Farmer's labor was valued at $15 /h. Milk not available to sell due to drug residues was considered available for calf feeding at half the market value of $.22 /lb or $.11 / lb. Milk not produced due to illness was assumed to occur secondary to reduced feed intake. Feed costs were set at $..09 per lb DM. Feed intake above maintenance yields 2.5 lb milk per lb DM consumed (NRC, dairy). Thus, the opportunity cost of milk not made is $.22 /lb minus the marginal feed cost per lb of milk produced ($.09 / 2.5 = $.036) or $.18 / lb. Delay in conception beyond the herd goal was assigned the value of $2.00 per day with no additional costs assessed for reproductive inefficiency.
Milk fever has been reported to occur in 4.7 to 10.8% cows at freshening.9,12,16,19 MF incidence was assumed to be 7% for the subsequent calculations. Death or euthanasia was reported to be the outcome for 5% of MF cows in Australia 18 and 4% in California.19 Cows not achieving satisfactory production levels after MF and that were therefore culled was reported to be 9% but this includes deaths.13 Death due to MF was assumed to occur in 4% and culling in 5% of cases. Some farmers treat MF themselves and some rely on veterinary treatments. Veterinarians were estimated to see 15 % of cases (often during emergency hours) for a per case treated by veterinarians charge of $50 for time. Drug costs for a case of MF were estimated at $8. Farmer labor required per case was estimated to be 1/2 h. There is no milk discard associated with treatment for MF. Lost production was reported by Cobo-Abreu7 as 130 kg. Delay in conception after MF was reported to be 13 d by Borsberry.5
Dystocia requiring farmer or veterinary assistance ranges from some pulling of a large calf to cesarian section or fetotomy. Published reports either use the dystocia score of 1 to 5 with 5 implying surgical intervention, or simply report assisted calvings. From reports that use the 1 to 5 scale, DYS scores of 2 or greater were included in the analysis. Case definition of unscored deliveries were considered inadequate for comparison. The incidence of DYS has been reported to be 21% with a higher incidence in primipera.10 Cows dying or euthanized following calving occurs in 1 % of DYS.10 Culling after DYS due to low milk production or complications such as hind limb paralysis occurs in 2.2 % of difficult calvings.19 RP is common following DYS. The effects of retained placenta and metritis are considered separately. Veterinary time for DYS averages .75 h and veterinarians assist in 15% of DYS. Drug costs for difficult births was estimated to be $30. Farmer labor for DYS was estimated to be 1 h. Milk discard after DYS is due to antibiotic and/or analgesic treatment for very difficult births including those requiring cesarian section or fetotomy (25% of DYS).10 Milk discard was estimated to be for 8 d at 45 lb for a total of 360 lb. Milk not made after DYS was reported to be 390 lb by Dematewewa.10 Delay in conception after DYS was reported to be 12 d.10
Retained placenta or metritis requiring systemic therapy occurs in 11 to 18 % of calvings.2,16,31,33 Cows with toxic peuperal metritis may die and the case fatality rate was estimated from our records at 1% and reported to be 1.5% in 29 California herds.19 Cows not achieving economical milk production and culled due to RP was estimated to occur in 6% of cases.2 We estimate that veterinary examination and treatment occurs in 5 % of cases. The time required for veterinary effort was estimated at .25 h. Treatment with systemic antibiotics occurs in 75% of cases (our estimate) with a drug cost of $15. More costly drugs may be used that do not require milk discard. Farmer labor required for daily evaluation and the course of treatments was estimated to be 10 minutes per day for 4 days or .67 h. Bartlett2 reported average milk discard for 7 d and a total of 225 lb. Milk not made due to RP was estimated to be 580 lb by DeLuyker9 and 265 lb by Bartlett.2 The authors selected 550 lb milk loss due to RP. Delay in conception after RP has been reported to be 12 d by Halpern,22 7 d by van Werven,33 32 d by Borsberry,5 19 d by Martin,27 and 12 d by Bartlett.2 The authors estimate that 15 d delay in conception is typical.
Ketosis has been reported to occur in 7 % of Ontario cows,12 18% of California cows9 and 17% of cows in our herd records. We chose 14 % incidence of KET for the following calculations. A few cows, 0.5 % of cases of KET, die of hepatic lipidosis or liver failure (our estimate). In addition, 5 % of cows are culled due to failure to adequately recover from KET.19 Veterinarians examine and treat 10 % (our estimate) of cases of KET. The time required to examine and treat a case of KET was estimated to be .25 h. Drug costs for treating KET include dextrose, corticosteroids, propylene glycol and other glucogenic substrates are about $10 per case. Farmers typically administer follow up treatments for 4 days at 10 min per day for .67 h. There is usually no milk discard due to ketosis treatments. Milk not made due to KET has been estimated to be 440 lb in New York Holsteins21 and 575 lb in a California dairy.9 We chose 506 lb milk loss for calculations. Delay in conception after KET was reported to be 1 d by Borsberry5 and was 10 d in 9 herds from our current herd database.
Left displacement of the abomasum was reported to occur in 7% of lactations by Eicker14 and 5.5% by Detilleux11 in New York Holsteins and 2% in a California herd.9 The incidence in our current herd dataset is about 4% and was used for the following calculations. Most cases occur in early lactation. Ten percent of cows with the diagnosis of LDA were gone from the herd within a month of diagnosis.14 Of these, 2% were estimated to have died from complications and the remaining were culled. Veterinary fees include examination and surgery ($150 + 20) or toggle fixation ($70 + 20). Correction of LDA was assumed to be done in the following proportions, 80% toggle and 20% surgery, for an average cost of $106. Drug costs were estimated at $10 per case of LDA. Farmer labor required for follow up treatment of LDA was estimated to require 1 h. Milk discard following LDA was estimated to be for 5 d at 50 lb in 25% of cases. Milk not produced with LDA was estimated at 770 lb by Eicker14 and 1225 lb by Deteilleux.11 We used 880 lb in our calculations. Delay in conception following LDA was 12 d from the records of our clinic.
Clinical mastitis is reported to be the most common disease condition of dairy cows with a lactational incidence rate of about 40%. Surveys of clinical mastitis in herds with low bulk milk SCC have reported incidence rates of 51% in 12 Pennsylvania herds,17 16 to 64% in 9 Ohio herds,23 and 31% in 43 California herds.19 Assuming that herds under consideration have low bulk milk SCC and are free of the contagious pathogens Streptococcus agalactia and Staphylococcus aureus, the major pathogens responsible for clinical mastitis are the environmental organisms Escherichia coli and fecal streptococci. The distribution of causes of clinical mastitis were assumed to be 40% E. coli or other coliforms and 40% streptococci and 20% other.17 Deaths due to coliform mastitis were reported to occur in 7 % of severe cases by Golodetz.20 Culling due to agalactia was 28 % in the same study. Severe clinical illness occurs in about 10% of coliform cases.32 Death seldom occurs due to streptococcal infection but culling due to chronic infection occurs in about 2 % of cases.32 The proportion of clinical mastitis cases with Arcanobacter pyogenes was 19 %24 and 9 %37 of cows for which veterinary care was requested. These cases are generally incurable and result in the loss of the affected quarter.
Death loses due to mastitis were 1.1% of cases in California herds.19 Overall cull rates for clinical mastitis were 9% for Ontario Holsteins13 and 7% in California herds.19 Culling for MAST in low bulk milk SCC herds in our herd database is less than 7%; a cull rate of 7% for MAST was used for calculation. Veterinarians see 10% of clinical mastitis cases (our estimate) and require .25 h for examination and treatment at a cost of $40. Drug cost per case was reported to be $30 for veterinary treated cases and $7.50 for farmer treated cases(recalculated form Blosser4 and our records). Farmer labor to treat mastitis was estimated at 10 min per day for 6 days for a total of 1 h. Milk discard was reported as 250 kg by Bartlett in one large Michigan herd with 316 cases in 1700 cows.3 The period of milk discard averaged 14 d in a Florida study; if affected cows produce 44 lb per day, total discard would be 280 kg.28 We selected 275 kg as typical. Milk not made due to MAST was estimated by DeLuyker at 128 kg for cases in early lactation and 281 kg for cases in mid-lactation.9 Bartlet estimated milk loss of 92 kg by fitting lactation curves to affected cows.3 The authors estimate that milk loss per case of MAST is 125 kg. A delay in conception may occur for cows with mastitis in early lactation. This reproductive inefficiency averaged across all mastitis cases was estimated to be 3 days.
Lameness incidence is described in a number of reports based on veterinary treatments or recall of farmers. Both of these methods underestimate the true incidence of painful conditions of cattle digits. Whitaker worked with good data from 185 herds in England and Wales and recorded an average incidence of 25% in a 12 month period in 1981-82 based on first ttreatments.36 Of these cases, veterinarians treated 6%, farmers treated 19%, and 1.4% were culled without treatment. The incidence by herd ranged from 2 to 55%. Thirteen Dutch herds served by a university herd health program had a lactational incidence rate of 9 to 49% during a 3 year observation period.1 Veterinary treatment rate for lameness in 1821 British herds was 5.5% of 136,800 cows during the year 1977.30 Prevalence of lameness in 17 herds in Wisconsin and Minnesota was 14% in summer and 17% in spring.35 The range by herd was 0 to 30% in summer and 2 to 33% in spring. With the increase in incidence of digital dermatitis since these reports appeared, some herds now have treatment rates over 170% per year.6 The authors believe that lameness is now the second most common clinical condition overall and the most common condition in some herds. Treatment rates by veterinarians, farmers, and hoof trimmers was 55% in a survey of 37 British dairies6 and in the data of our clinic averages 38%. Few animals die but some are so disabled that they are not salvagable. The authors estimate that 2% of lame cows are disposed of without salvage value. Lame cows are often culled for apparent low production or reproductive failure. In 13 Dutch herds cullling attributed to lameness was 9% of cases.1 In 185 British herds lameness was given as the reason for culling 5.6% of lame cows.36 In a retrospective case control study of 427 lame cows in 17 British herds, the lame cows had a 10% higher cull rate.8 Culling for LAME was chosen to be 12% based on the data from our clinic.
Veterinarians examine and treat about 30 % of lame cows in our practice but this is probably atypical. The authors estimate that veterinarians treat 5 % of LAME cases nationwide. The typical time for treating lameness is .35 hr. Farmers or hoof trimmers treat the remainder of LAME cases with an average investment of .5 hr time. Some cases of lameness require drug therapy and others require supplies such as bandages or hoof blocks. The average drug and supply cost for a LAME case is estimated at $20. Milk discard for some treatments (5 % of cases) is for 10 days at 50 lb for a total average discard of 25 lb. Milk not made due to LAME was estimated by DeLuyker9 at 330 lb and by Kossaibaiti25 at 275 lb for 90 British herds. Research in our group has estimated milk loss of about 600 lb from data collected in 1995 and 940 lb from data collected in 2006. Delay in conception occurs for cows with LAME in early lactation. The delay was 10 d for LAME before 35 DIM, 30 d for LAME between 36 and 70 DIM, and an average delay of 11 d for all LAME cases;; including cows pregnant when lame.26 Dutch cows in 13 herds lame at any time in lactation conceived 7 d later than non-lame herdmates and in 21 herds 9 d later.1,15 Lame cows in 17 British herds conceived 14 d later than controls.8
Other reports on the costs of diseases of dairy cattle in the United States are not directly comparable to the current analysis. Data collected by interviews for the National Animal Health Monitoring System in California in 1988 was described as an aggregate of direct costs or prevention costs.34 This information was prepared to estimate the overt costs of diseases and does not consider lost income.
Veterinarians and farm advisors can use the cost estimates and incidence and outcome estimates for the diseases described in this report to evaluate new strategies for disease management. The average values will not be valid for any given farm but can serve as guidelines to major areas of loss associated with common diseases. Efforts to minimize disease losses should be tailored to each farm with consideration of the incidence and outcome for cases of disease on that particular farm. The economic values in this report will serve as a guide for where to stress prevention or improved detection or more appropriate or timely interventions.
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