Herd health programs and working with commercial goat dairies (Proceedings)
Herd health programs developed by veterinarians in cooperation with producers strive to maximize health and production while decreasing the incidence of a variety of economically important diseases.
Herd health programs developed by veterinarians in cooperation with producers strive to maximize health and production while decreasing the incidence of a variety of economically important diseases. Biosecurity programs reflect the interaction between the animal and its ability to resist disease, a variety of infectious agents and the environment. Producers need to be educated that changes in management practices can be very cost effective in reducing the incidence of preventable diseases and decreasing the need for pharmaceuticals. Insidious diseases such as caprine arthritis-encephalitis, mycoplasma, caseous lymphadenitis and Johne's disease do not respond to treatment regimens and are best prevented through adoption of specific pathogen prevention programs. Lastly, cleanliness and good nutrition cannot be over-stressed to prevent disease and increase productivity.
Commercial goat dairymen agree that one of the greatest challenges they face is finding a food animal veterinarian that has a working knowledge of goats and their diseases. One producer suggested dairymen purchase copies of Smith and Sherman's Goat Medicine and share it with interested veterinarians. Another producer commented that there is a general lack of information about management strategies, and another commented that the information is available but is not readily accessible. The dairy goat industry is expanding quickly in some areas and new producers often have minimal background or education in livestock prior to buying goats and starting a dairy. There is obviously a demand for veterinarians willing to work with goats.
Good herd health programs assume that certain general management practices are performed. Vaccination of young stock and pregnant does against Clostridium perfringens types C & D and tetanus decreases the incidence of these two common diseases. Providing newborns with one ounce of colostrum per pound of body weight three times in the first 24 hours of life provides antibodies against pathogens in their specific environment. Providing feed off the ground and keeping water sources clean help prevent parasitism. Separating newborns from the adult population at birth prevents transfer of microbes and parasites from infected adults to immunologically naïve young. Addition of coccidiostats to milk, milk replacer, water or creep feeds markedly decreases the incidence of coccidiosis.
No vaccine or drug can replace keeping the environment clean. Removing dirty bedding and opening a closed barn prevent parasitism, pneumonia and paratuberculosis. The incidence of scours in kids is markedly reduced when their pens and feeding devices are cleaned frequently. In certain environments, the use of raised floors or dry lots can decrease parasitism. Encouraging exercise by housing animals in large paddocks or pastures reduces the incidence of ketosis, hypocalcemia and obesity. Adequate amounts of nutritious feeds appropriate for the type and number of animals present prevents nutrient deficiencies and allows livestock to maximize productivity. Well-fed goats with adequate trace minerals appropriate to the local feeds are more likely to mount an effective immune response when challenged.
Eradication and control programs prevent major disease problems such as caprine arthritis-encephalitis, mycoplasma, caseous lymphadenitis, and Johne's disease. Many producers utilize test and cull programs for CAE and Johne's disease. Producers remove kids from the adult population at birth, feed heat-treated colostrum and pasteurized milk, and permanently separate the clean herd to decrease the incidence of these four diseases. The new clean herd and the adult population should be separated by at least a ten foot alley, and the two populations should not share shelter, feed or water devices. Closed herds do not purchase animals from other herds, attend shows, board outside animals, share transportation, or allow any contact of their animals with other livestock. Encouraging commercial producers to raise all female kids on a specific pathogen prevention program increases the sale value of extra replacements and can provide an extra source of income for the herd.
While many producers see the benefit of developing herds free of these insidious diseases, not all are convinced that the effort involved in developing a clean herd will provide an increased economic return. Does with chronic wasting diseases do not live as long and do not produce as much milk on a yearly basis as does under the same management without chronic disease. Animals infected with these chronic diseases are permanently infected and serve as a source of contagion to other livestock. Many progressive commercial herds enjoy greater productivity and sales of healthy stock after adopting a prevention program and eliminating these chronic diseases.
In order to prevent introduction of new diseases into the commercial herd, goats should be tested for brucellosis, caprine arthritis-encephalitis, mycoplasma, caseous lymphadenitis, paratuberculosis, parasites, mastitis and tuberculosis prior to purchase. Vaccination status and nutritional history should be determined. If possible, young goats that have not been previously bred should be purchased to decrease exposure to pathogens transmitted through breeding. Milk from lactating does should be cultured prior to purchase to prevent introduction of new mastitis pathogens into the herd. As necessary, herd additions should be treated for internal and external parasites upon arrival. When transporting incoming stock, a clean vehicle should be used and it should be cleaned again before being used for another purpose.
Many producers cannot elude the appeal of the show ring. Producers should arrive early and pick pens as far away from other herds as possible. Tack pens, tarps and walls or fences should be used as barriers between herds, and producers should avoid penning back to back with other herds. Herds should be grouped by health status or prevention programs. Pens should be cleaned on arrival and bedded heavily to prevent transmission of soil-borne organisms. Pens should be cleaned frequently, and the goats should not be over-crowded. Gastrointestinal upsets can be minimized by maintaining a steady diet and feeding the same roughage and concentrates as the home herd. Upon return home, the exhibited goats should be treated as if they were new additions and quarantined separately from the home herd.
New arrivals and returning herd mates should be housed separately for a minimum of 30 days to prevent introduction of new diseases into the main herd. There should be no contact between the new stock and the main herd through feeders, fences, housing or water sources. If possible, different people should care for the main herd and the new acquisitions using separate equipment. If labor is in short supply, the main herd should be cared for first before working with the new stock. Any equipment used on the new stock should be cleaned before using it with the main herd. If the new additions have not been vaccinated or treated for internal and external parasites on the same program as the main herd, then they should receive this treatment while in quarantine. If lactating animals are entering the herd, milk them last, use separate towels for each animal, and clean the equipment thoroughly after milking the new stock. Producers should observe new animals at least twice daily, examine any that appear abnormal promptly and seek veterinary advice early in the course of a problem.
People, equipment and animals can transmit disease, and infectious agents can be carried on hands, clothing, boots and pets. Producers should not wear their barn clothes to another goat producer's facility, and they should leave their dogs at home. If a visitor arrives with a dog in tow, it should be kept in the vehicle away from the herd. Visitors should wear disposable plastic boot covers or washable boots and should wash their hands before and after visiting the livestock. Herds should not exchange equipment unless absolutely necessary, and then it should be thoroughly cleaned before using it and again before returning it. Recommend that producers selling stock have the buyer park on the road and then walk the animals off the property to the vehicle. Likewise, dead animals should be placed at the edge of the property so that the renderer will not enter the pens or come in contact with the livestock.
Many commercial dairy health issues could be prevented or decreased by adopting the practices outlined. Producers often look at the immediate health crisis and do not realize that it could have been prevented by changes in management. One of the more common health problems on a commercial dairy is ketosis or pregnancy toxemia. Manipulation of the herd nutrition and environment can help prevent this very difficult to treat problem. Many dairymen do not separate their pregnant dry stock from the milking herd. Pregnant dry goats housed with the milking strings have access to a higher nutritional plane than is required for their non-lactating state and become obese. Separating dry stock from the milking herd and observing individual goats for appropriate body condition dramatically decreases the incidence of ketosis. Increasing exercise for pregnant does also improves energy metabolism, and this is easily accomplished by moving the feed, water and shelter as far apart as possible. Addition of niacin to the grain ration has been very helpful in reducing ketosis in dairy cattle, and goatherds that have incorporated niacin in the dry goat diet see a similar effect.
Digestive and respiratory diseases in kids are also reported as major health issues for several producers. Removing kids from the adult population to clean, dry housing at birth helps prevent transmission of pathogens from the adult herd to the naïve young. Feeding adequate levels of good quality colostrum helps prevent enteric disease from a variety of pathogens. Providing adequate pen space and reducing overcrowding increase growth rate and decrease the spread of disease if a pathogen enters the herd. Segregation of kids by age, maturity and body size improves access to feed and increases growth rate while decreasing the impact of parasites such as coccidia and cryptosporidia. Appropriately timed use of coccidiostats in milk, milk replacer or feed dramatically increase growth rate and survival.
Changing management practices so that does kid in the fall and winter and maintain high milk production through the winter can make a tremendous difference in how much money the dairy earns for the same amount of annual milk production. Many milk cooperatives pay a premium price for winter milk and most quotas are established by how much winter milk a producer can generate. Does in late lactation often have high somatic cell counts unrelated to incidence of mastitis, and introducing recently kidded does in winter decreases the bulk tank somatic cell count to help meet regulatory standards.
Regulations regarding the use of drugs that alter reproduction vary by country, but treatment with prostaglandins and progestagins have been used to stimulate estrus outside the normal breeding season. The 1994 Animal Medicinal Drug Use Clarification Act prohibits the use of drugs to alter reproduction in goats in the United States. Some herds meet this challenge by using fluorescent lights to artificially increase day length both for out of season breeding and maintaining higher milk production in the winter. Provision of twenty hours of daylight for two months in deep winter followed by return to normal day length will bring goats into estrus several weeks later. Sudden introduction of an odiferous buck into a pen of does that have not been housed within the sight or smell of a buck will stimulate cycling. Both are effective techniques that require simple changes in management. Increased use of ultrasound also improves reproductive efficiency by allowing accurate diagnosis of false pregnancy as a cause of reproductive failure.
Commercial goat producers should be aware of the many management practices pioneered in cattle dairies that decrease the incidence of mastitis. Employee use of disposable gloves during milking improves cleanliness and helps prevent transmission of mastitis from one goat to another. Use of a strip cup to observe the first milk from each teat for abnormalities before every milking can help identify problem animals early for diagnosis and treatment. Goat-side use of the California Mastitis Test on animals with unusual milk or changes in volume aids in early detection of mastitis. Dipping the teats with a 0.5% iodine solution followed by drying of the teats with a single service paper or cloth towel prior to milking helps prevent introduction of pathogens into the teat. Milk removal should begin within 30 seconds of teat preparation in order to maximize effect of oxytocin release and should stop when full streams cease. An effective post milking dip should be thoroughly applied to the bottom two thirds of the teat after milking to prevent bacteria from entering the open teat orifice. Separation of affected animals to the last milking string can help prevent spread of mastitis. Herds with a history of mastitis caused by Staphylococcus or gram negative bacteria may benefit from use of specific bacterins and toxoids. Providing adequate levels of trace minerals such as copper, zinc, and selenium appropriate to the rest of the diet can improve immune function and decrease the incidence of mastitis.
It is difficult, if not impossible to prevent all disease problems on a goat facility. Use of prevention programs, sound management practices, cleanliness and eradication programs can provide the goat producer with a higher level of herd health.