We have protected the nucleus herd from outside threats, now it is time to worry about controlling diseases which already exist in our herd. The first goal is one of biocontainment. That means we want to limit the disease to a certain population of animals in the herd or to a certain geographic location in the herd and not allow it to spread from there. Let’s say we have a goat that develops a Caseous Lymphadenitis abscess. This is caused by a highly contagious bacterium which can live in the environment for about 6 months. The first goal would be to isolate the goat in a pen away from the rest of the herd. That way if the abscess ruptures prior to being treated it will not contaminate other goats in the herd or the environment.
The second goal might be to get a non-infected kid off of this doe. We know that kids may be infected by ingesting colostrum and that the longer the kid stays with its mother the more likely it is to become infected. Our plan here might be to have a “clean herd” and a “dirty herd”. The infected doe is the dirty herd and since the rest of the herd is uninfected they are the clean herd. If the newborn kid can be removed from its mother without becoming infected then it can join the clean herd. The best plan is to remove the kid at birth. Raise it on a bottle and place it with the clean herd. To increase the possibility that the kid was not infected we could do a blood test on it when it gets to be 6 months of age.
Visitors moving through an animal enterprise can serve to spread disease from one area to another. When visitors enter the unit they should visit only the areas they need to see and they do it in order of the livestock disease susceptibility. This means that they would visit the neonatal unit first, the breeding unit next, then gestating animals, then weanlings or replacement doelings and lastly any animal that is sick and needs attention. The concept here is that baby goats are very easily infected with disease agents and that as they age they become more and more disease resistant. The cycle begins again when the doe becomes pregnant and has a fetus inside her which is again very susceptible to disease. Visitors would never go in reverse order or go back to a unit after they had visited the next unit. These same rules apply to employees on the farm.
Feeding systems
Feed and feed buckets can serve as fomites within the different units of the farm. If you have two houses of kids you are bucket feeding and you exchange buckets between the houses then you are getting cross contamination with pathogens between the two houses. The same would hold true for feed and feed buckets.
One of the common mistakes people make is using equipment to move manure and also to move feed. For instance a front end loader on a tractor is used to scrape manure out of the lot and is then used to haul bails of hay to the goats in the pasture. The hay has become contaminated with feces and could serve to spread parasites or diseases like Johne’s disease. On a smaller scale this feces to hay contamination can be done by cleaning fecal pellets out of a trough with the same scoop that you use to get feed.
Goats are very adept at climbing into troughs and defecating. This serves as a source of infectious material for other goats. This can be avoided by making feed troughs and hay racks goat proof. Goats love to get on top of round bales and while they are on top they defecate and urinate. This serves as a mechanism of disease transfer but also results in the goats refusing to eat the soiled hay. Round bales need to be placed in round bale feeders that allow goats to eat the hay but not get up on top of it. This will prevent fecal to oral disease transmission and also minimize the amount of hay wasted. Alternatively, hay can be fed in limited quantities to limit the amount of waste.
Milk feeding systems
In general meat goat kids receive milk only from their dams. There is possibility of disease transmission but it is fairly minimal. Under some circumstances kids are fed or supplemented with milk from other does and sometimes with milk from does from other farms. Non-pasteurized milk can contain a variety of pathogens including those that cause mastitis (e.g., Staph and Strep), diarrhea (e.g., E. coli, Salmonella), respiratory disease (e.g., Pasturella and Mycoplasma), abscesses (Corynebacterium pseudotuberculosis) and a variety of systemic diseases (e.g., Listeriosis, CAE, and Brucellosis). The odds of one doe having disease may be low but if you pool milk from 100 goats then you are increasing the odds of exposing the kid to disease risk. Disease transmission by non-pasteurized milk is a huge problem for dairy goat operations. Pasteurizing milk or feeding a milk replacer eliminates this possibility of disease transmission.
Watering systems
Water in waterers can become a source of community infection. If every goat in the herd drinks out of the trough and one of them has sores on its mouth caused by Contagious Ecthyma then the virus deposited in the waterer may well infect a substantial number of goats. This problem can be minimized by keeping troughs filled with fresh water at all times and by chlorinating water. City water is chlorinated out of the tap. Well water can be chlorinated by adding chlorine to it. The rule of thumb here is that if you should not expect goats to drink water that you would not drink.
Manure programs
The invention most responsible for the longevity of humans is not the miracles of modern medicine but the invention of the flush toilet. Animals that are exposed to feces and forced to eat them have more disease problems then those that are not forced to eat feces. Why would a goat eat feces? If you watch goats eat you will learn that they are very picky eaters and that they especially avoid eating close to fecal pellets. They don’t even like to eat grass that is close to fecal pellets on the pasture. However, if they get really hungry they will overcome this natural instinct to avoid feces.
Goats that are forced to lie in feces will be forced to eat feces. The doe that lies in feces gets them on her teats. Her kid nurses her and ingests feces along with its milk. The doe later grooms herself and ingests feces from her hair coat. How do you avoid the problem? Goats hate to lie in feces or on wet ground. Given a choice they like to lay up high and dry. Slatted bedding frames can be built that will allow goats to be off the ground and in a dry environment. Any feces they pass go through the slats to the area under the goats. Wooden pallets function in the same way.
Periodically, the feces need to be removed. They will be composted by putting the feces in a pile. The temperatures in the pile will help to kill many of the pathogens normally found in feces. It also improves the quality of the fertilizer you are producing. Make sure the manure pile is contained and that there is no run off of liquid from areas of manure concentration to pastures where goats are grazing. In particular, make sure there is no runoff from the feces of adult animals to pastures that house immature animals.
Feces should be applied to crop land, not to pastures. Fertilization of pastures with raw goat manure will result in disease transmission to grazing animals. The most important disease transmitted by feces is intestinal parasites. Fertilization of a hay field with goat manure and the subsequent cutting of a hay crop will not result in animals eating disease producing agents.
All In All Out
Another important concept of biocontainment is that of “All In All Out” (AIAO). This means that we bring a set of animals into a facility, raise them to a specified production level, remove all animals at the same time, then clean and disinfect the facility prior to introducing the next group. This concept was invented by the poultry industry and has improved their health standards dramatically.
Let’s apply this to a simple example to a goat farm. We buy 100 goats and put them on a 10-acre pasture. Over a period of months the goats contaminate the pasture with parasite eggs which hatch into larvae. We recognize the parasite problem and remove all but ten goats from the pasture. These ten goats will continue to maintain levels of parasite contamination on the field. Months later we put 100 goats back on the pasture. They will quickly become parasite infected just like our original group. If we had removed all goats from the pasture and let the pasture sit or used it for a hay field, the pasture would have been parasite-free for our next group. This same principal can be applied to kidding barns and weanling pens. When a group of animals is ready, move all animals out. Most parasites and pathogens can’t live for very long without their hosts. Continuous occupation results in continuous maintenance of pathogens. This cycle can be broken by removing the host and sanitizing the facility.
Next
Module Home
Certification Table of Contents
Browsing Table of Contents