Development and initial validation of a dairy biological risk management assessment tool

Bickett-weddle, Danelle
Major Professor
James A. Roth
Howard S. Hurd
Committee Member
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Veterinary Microbiology and Preventive Medicine

Disease prevention protocols on dairies, either aimed at keeping disease out (biosecurity), preventing spread of disease on the farm (biocontainment), or reducing the infectious burden have always been a concern. There are a myriad of recommendations available to dairy producers to help minimize disease threats. Dairy operations differ in management style and tolerance of risk, thus there is not a one–size–fits–all answer to minimize disease entry and spread. Risks must first be identified before they can be managed.

Dairy biological risk management (BRM) materials were developed to educate producers and their advisors about identifying disease risk management practices and preventing disease entry and spread to the animals in their care using the concepts of risk analysis: risk perception, risk assessment, risk management and risk communication. The BRM toolbox contains a background document reviewing published disease management protocols for dairy operations, risk management assessment questions to identify various strengths and weaknesses of disease introduction and spread, management protocols for each identified risk, and risk communication tools, all based on disease prevention through five routes of transmission (aerosol, direct contact, fomite, oral and vector-borne). The outcome was a set of peer-reviewed resources available online, free of charge, for dairy producers and their advisors to utilize.

One objective of this study was to report the current biological risk management practices of California and Midwest dairies of different sizes and management styles. This was accomplished by ascertaining producer-reported prevention practices through on-farm interviews utilizing two questionnaires on 80 dairy operations in California and the Midwest. Herd size ranged from 92 to 3,550 head (average 772). There were 64 Holstein herds, seven Jersey herds, one Guernsey herd and eight mixed herds. Production (305 day mature equivalent) ranged from 15,564 to 30,586 pounds (average 24,113) and somatic cell count (SCC) ranged from 110,000 to 954,000 cells/mL (average 284,873).

Reported management practices on a majority of the dairy operations included examining all feedstuffs closely for manure, mold, foreign material, and overall quality (95%), investigating animals that will not eat or do not consume all of their feed (95%), humanely and promptly euthanizing animals that are not going to recover (93.7%), keeping stalls clean (scraped at least one time daily) (92.3%), inspecting animals daily for signs of illness (90.0%), keeping alley ways clean (scraped or flushed at least one time daily) (87.5%), knowing the origin of all replacement heifers (86.3%), having a fly control program (81.3%), and regularly maintaining the dry lot area to prevent manure buildup and areas of stagnant water (80.0%).

The top three responses for the biggest perceived disease risk/challenge included mastitis—all types (30 herds), FMD (11 herds), and Johne's disease (nine herds). Most farms (70%) introduced animals and the highest SCC were in the herds that introduced lactating and dry cows. Very few of the herds had isolation facilities (22.5%) or utilized quarantine (22.0%) for newly introduced or returning animals. Visitors were reported to exceed 10 per week on 60% of the operations yet only 30% had any type of protocol regarding boots, animal contact, or signing a visitor log. Only 16.3% of dairies utilized their veterinarian's training and skills to necropsy animals that died of undetermined causes.

A majority of dairy operations (71.3%) complied with removing calves at birth prior to nursing. Only 36.3% of herds reported collecting colostrum within 2 hours of calving but nearly 74% of herds fed colostrum by six hours of age. Thirty-five herds (43.7%) in this study pooled colostrum from multiple cows; large herds (>506 head) were more than twice as likely to pool colostrum as compared to smaller (<505 head) herds.

Scientific data that correlates management practices to production parameters is sparse. The overarching goal of this project was to identify disease prevention practices that correlated with positive outcomes on dairy operations (higher milk production, lower somatic cell count). Introducing animals to a herd did not prove significant when multiple prevention practices were included in the final model, but it remains a critical control point as an independent prevention practice for both milk production and quality.

Prevention practices that correlated with higher milk production and lower somatic cell count included management styles characterized as ’attention to detail’. For instance, fly control, having a SCC less than 200,000 cells/mL, inspecting animals daily, cleaning alleyways, and preventing young animals from contacting manure from older animals were associated with higher than breed average 305 day mature equivalent milk production. The four disease prevention practices that were associated with a lower SCC included removing calves at birth prior to nursing, collecting colostrum within two hours of calving, giving a second dose (1/2 to y gallon) of colostrum 12 hours after the first feeding, and having a fly control program.