Economic costs of recorded reasons for cow mortality and culling in a pasture-based dairy industry.

The objective of this study was to determine the economic costs associated with different reasons for cow culling or on-farm mortality in a pasture-based seasonal system. A bioeconomic model was developed to quantify costs associated with the different farmer-recorded reasons and timing of cow wastage. The model accounted for the parity and stage of lactation at which the cows were removed as well as the consequent effect on the replacement rate and average age structure of the herd. The costs and benefits associated with the change were quantified, including animal replacement cost, cull salvage value, milk production loss, and the profitability of altered genetic merit based on industry genetic trends for each parity. The total cost of cow wastage was estimated to be NZ$23,628/100 cows per year (NZ$1 = US$0.69) in a pasture-based system. Of this total cost, NZ$14,300/100 cows worth of removals were for nonpregnancy and unknown reasons, and another NZ$3,631/100 cows was attributed to low milk production, mastitis, and udder problems. The total cost for cow removals due to farmer-recorded biological reasons (excluding unknown, production, and management-related causes) was estimated to be NZ$13,632/100 cows per year. Of this cost, an estimated NZ$10,286/100 cows was attributed to nonpregnancy, mastitis, udder problems, calving trouble, and injury or accident. There is a strong economic case for the pasture-based dairy industries to invest in genetic, herd health, and production management research focused on reducing animal wastage due to reproductive failure, mastitis, udder problems, injuries or accidents, and calving difficulties.

Salmonella Brandenburg: case-control survey in sheep in New Zealand.

AIM: To identify environmental, management and animal risk factors associated with the occurrence and severity of disease attributed to Salmonella Brandenburg infection in sheep. METHODS: A retrospective case-control study was undertaken, and details of disease prevalence and farm management methods were collected from two affected regions in southern New Zealand. Associations between possible risk factors and disease attributed to S. Brandenburg were evaluated using odds ratios. A case-control approach was used to assess risk factors associated with outbreaks of disease at the farm level, using unaffected farms as controls. A separate analysis was then performed within affected farms only, to assess risk factors associated with increasing severity of disease. RESULTS: Data were collected from 405 farms containing a total of 1,170,737 ewes. Of the 177 case farms, 172 (97%) had diseased mixed-age ewes, 78 (45%) had diseased two-tooth ewes and eight (5%) had diseased hoggets. Increased odds of farms being affected with S. Brandenburg were reported for farms that strip-grazed sheep, and as total numbers of sheep increased. Reduced odds of being affected were associated with feeding crops, and hilly terrain on those farms not feeding crops. Within affected farms, increased severity of disease was associated with strip-grazing and feeding hay in TT flocks, and later removal of rams in MA flocks. Reduced severity of disease was associated with shearing or crutching after July, and vaccination of sheep against Salmonella spp. CONCLUSIONS: Salmonella Brandenburg occurred in flocks that reported using intensive farming methods and that maintained high numbers of sheep. CLINICAL RELEVANCE: Risk factors associated with the occurrence and severity of the disease due to S. Brandenburg have been identified. This information is necessary to identify preventative and control measures that may be effective in reducing the risk of disease.