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HARVESTED
FEEDS
Harvested feeds such as hay, silage and grain may be exposed to insecticides,
herbicides and fungicides during the growing season. These pesticides
have preharvest withdrawal times, and following label directions will
ensure that residues do not remain on the feeds when they are harvested
and fed to livestock. If feeds are purchased, inquiries can be made
about the preharvest use of chemicals. If possible, it should be determined
which pesticides were used and when they were applied relative to harvesting.
These precautions will help assure that milk or meat products are free
from residual chemicals. When pesticides with preharvest withdrawal
times are used in the production system, records must be kept of such
use. Records should include the feedstuff that was treated with the
insecticide, herbicide or fungicide, the date the feedstuff was treated,
the specific product with which it was treated, the person who applied
the pesticide to the feedstuff and the preharvest withdrawal time.
MEDICATED
FEED ADDITIVES
The Federal Food, Drug, and Cosmetic Act provides that a medicated feed
containing an animal drug is considered adulterated if it is not produced
in conformance with current Good Manufacturing Practices. Manufacturers
of medicated feeds that are not used in the correct manner are subject
to regulatory action. Refer to Appendix B for the objectives for both
registered and non-registered facilities.
Larger sheep operations that use highly concentrated medications may
be required to register with FDA via a FD-1900 permit. Pre-mix or formulated
supplements typically used by smaller sheep operations do not require
FDA registration of any type. Contact the SSQA Coordinator with questions
about specific production units that may need FDA registration.
The proper mixing of medicated feeds is critical to prevent chemical
residues in meat and milk. Commercial feed companies are required by
the FDA to follow objectives. Sheep producers and feeders who mix their
own medicated feeds also are required to follow objectives. This applies
to anyone using feed additives such as antibiotics, coccidiosis control
medications, or dewormers.
GMPs provide guidelines for the proper use and maintenance of mixing
equipment, methods of cleaning such equipment to prevent contamination
of unmedicated feeds, proper record-keeping and feed storage.
(Sidebar: for more information on the objectives, contact FDA-CVM, 7500
Standish Place, Rockville, MD 20857; 301-594-1724. Ask for the HHS publication
number 89-6047 entitled "Objectives For Medicated Feed Manufacturers
Not Required To Register With FDA;" also see product use appendix)
Properly adjusted and maintained mixing equipment is essential for the
prevention of drug residues. The withdrawal time of a drug (the time
from last treatment to the time when products from the animal can be
safely consumed) is based on the recommended dosage and feeding period.
Careful reading of the feed additive label, checking all equipment,
measuring ingredients accurately and following mixing and clean-out
directions will help ensure that drug residues do not occur in the meat
and milk products.
It is important to thoroughly clean equipment after using medicated
pre-mixes. As little as 20 pounds of medicated feed can contaminate
a ton of unmedicated feed and can cause detectable drug residues. Medicated
feeds should be mixed last and the equipment should be thoroughly cleaned
following mixing. Feeders and storage facilities containing medicated
feed must be cleaned at the conclusion of the treatment period in order
to follow proper withdrawal schedules. GMPs also require that records
be kept on the purchase, use and sequence of mixing of feed additives.
Records should be kept for at least one year.
ANTIBIOTIC
RESISTANCE
Antibiotic resistance is receiving severe public scrutiny because of
the concern that treating livestock with antimicrobials may result in
resistance of human pathogens to administration of antimicrobials in
treatment of human illness. Currently, the best way to minimize development
of antimicrobial resistance is to follow the Judicious Antibiotic Use
Guidelines as outlined by the Academy of Veterinary Consultants.
1. Preventive strategies, such as appropriate husbandry and hygiene,
routine health examinations, and vaccinations, should be emphasized.
2. Judicious use of antimicrobials should be within a veterinarian-client-patient
relationship.
3. Therapeutic alternatives should be considered prior to using
antimicrobial therapy.
4. Avoid using certain antimicrobials for initial therapy that
are considered important in treating refractory infections in human
or veterinary medicine.
5. Utilize culture and susceptibility results to aid in the selection
of antimicrobials, whenever possible.
6. Confine therapeutic antimicrobial use to proven clinical indications,
avoiding inappropriate uses such as for viral infections without bacterial
complication.
7. Regimens for therapeutic antimicrobial use should be optimized
using current pharmacological information and principles.
8. Use narrow spectrum antimicrobials, whenever possible.
9. Therapeutic exposure to antimicrobials should be minimized
by treating for the shortest period of time possible.
10. Limit therapeutic antimicrobial treatment to ill or at-risk
animals, treating the fewest animals possible.
11. Steps should be taken to minimize environmental contamination
with antimicrobials due to their use, whenever possible.
12. Accurate records of treatment and outcome should be used
to evaluate therapeutic regimens.
13. Label instructions should be followed carefully when appropriate.
Extra-label antimicrobial therapy should be prescribed only in accordance
with the Animal Medicinal Drug Use Clarification Act (AMDUCA) amendments
to the Food, Drug, and Cosmetic Act and its regulations.
There are several position statements in the industry regarding antibiotic
resistance in bacteria. The Animal Health Institute states that antibiotic
resistance is a top concern of the animal health industry.
The American Meat Science Association developed the following position
statement that has been forwarded from the Regulatory Affairs Committee
to the Board of Directors for adoption. The draft position states "While
it appears that animal agriculture contributes minimally to the increasing,
global problem of antimicrobial resistance in human pathogens, the burden
of addressing the issue should, and will, shift to users of antimicrobials
that do not prescribe drugs specifically for therapeutic treatment of
disease (particularly in human beings). AMSA supports policy development
based on sound scientific principles, and research, particularly at
the preharvest level, that will reduce the risk of any human pathogens
being transmitted to consumers via the food chain. Furthermore, AMSA
strongly advocates implementation of process control programs in livestock
production, and encourages producers to develop strong veterinarian-client-patient
relationships and to comply with Judicious Antimicrobial Use Guidelines."
PESTICIDES
BACKGROUND INFORMATION
Internal and external parasites are a constant economic concern to sheep
producers. Parasites directly affect animal performance, transmit disease
and affect the wholesomeness of sheep products. Improperly handled pesticides
can lead to residue contamination, feed contamination, by-product contamination
and environmental damage. Only pesticides approved by EPA, FDA and USDA
can be used for sheep treatment. These products must be used in compliance
with label directions. Chemicals applied to sheep become concentrated
in the lanolin. The proper use of approved insecticide products will
prevent harmful chemical exposure to the users of lanolin-based products.
DEWORMERS AND FLUKICIDES
Internal parasites such as worms, flukes, and nasal bots can cause undue
stress and permanent economic damage to sheep. While including a dewormer
and/or a flukicide in the processing schedule may be economically sound,
improper administration leads to residue problems and a high percentage
of abscesses and skin lesions. Consult your veterinarian for further
information.
INTERNAL PARASITE CONTROL
Internal parasitism is a common problem. Scars in the liver and cysts
in the muscle, both due to internal parasites, cause tissue condemnation
at the harvest plant. In addition, the presence of parasites can reduce
the performance and productivity of affected animals. Animals with low
parasite loads grow more efficiently than those with heavier parasite
burdens. There are also fewer carcass condemnations from sheep with
few parasites.
The control of parasites depends upon careful management of the flock's
environment as well as strategic use of dewormers. Avoiding exposure
of sheep to parasites is the best method of control, but that is not
always possible. Range flocks have fewer problems with internal parasites
because they seldom regraze the same area during a season. More intensively
pastured sheep tend to build up parasite loads as the season progresses.
Sheep kept in dry lots and fed from feeders have a lower risk of being
exposed to internal parasites than do grazing sheep.
Veterinarians can detect internal parasites through the use of a fecal
exam. Periodic fecal exams indicate when the number of parasites is
increasing and allow recommendations for treatment with dewormers. Internal
parasites can develop resistance to medications. To test for resistance,
a fecal exam can be administered both before and after treatment. A
strategic deworming program based on the results of fecal exams is less
expensive and more effective than deworming flocks on a fixed schedule.
It also prevents unnecessary exposure of the flock to drugs that are
not needed. Such exposure makes parasites more resistant to drugs.
Some management recommendations that will help control internal parasites
include:
1. Place harvested feeds in feeders, not on the ground. Use feeders
that are designed to keep dirt and manure out. Most internal parasites
are passed to sheep when they consume parasitic larvae from the ground,
or manure along with their feed.
2. Provide clean pastures for grazing. These include pastures
that were not grazed by sheep the preceding year, those from which crops
were harvested the previous year or fields which were grazed by another
species. The grazing of crop residue after harvest is another example
of a clean pasture.
3. Remember that lambs are more susceptible to parasites than
adult sheep. If clean grazing areas are not available, it may be better
to wean the lambs and raise them in dry lots than to pasture them in
areas where parasite build-up is a problem.
4. Have fecal exams conducted periodically to determine the need
for treatment.
5. Do not allow dogs, cats or wild carnivores to eat dead sheep
or the offal from harvested animals. Several parasitic diseases are
passed from sheep to carnivores and then back to sheep; some of these
diseases can be transmitted to humans. Carcasses and offal, including
placentas, should be buried or burned.
A good parasite control program will benefit the producer in many ways:
(a) the animals will be healthier and more resistant to other infections,
(b) lambs will grow more efficiently, (c) the use of management techniques
to control parasitism will reduce the amount of medication needed, and
(d) a reduction in parasite problems will lead to fewer carcass condemnations
at the harvest plant.
EXTERNAL PARASITE CONTROL
Like internal parasites, external parasites result in poor quality sheep
products and lost income to producers. Common external sheep parasites
include lice, keds, mites and ticks. These parasites bite the animal
and cause skin irritation, resulting in rubbing, scratching and chewing
of the skin by sheep. This can lead to damage to the wool and pelt.
Some parasites also feed on the sheep's blood, causing blood-loss anemia,
especially in lambs. The result is unthrifty, poor performing sheep.
The best time to treat for external parasites is immediately after shearing.
All sheep should be treated with an approved product according to label
directions. If infestations are heavy, the treatment should be repeated
two weeks later. Pyrethrin-type insecticides are safe and effective
and can be used on pregnant ewes. Unapproved products should never be
used; their use can result in illness in the sheep as well as chemical
residues in products that contain lanolin.
A regular program for treating and preventing external parasites is
an important part of a flock health program. Treatment of sheep at shearing
time is recommended. Benefits include increased comfort for the animals,
improved performance and higher quality wool and pelts.
BIOSECURITY
Biosecurity measures are becoming valuable in preventing and controlling
transmission of infectious diseases and pathogens. Biosecurity can be
defined as management and hygiene practices that decrease the risk of
introducing or spreading infectious diseases or pathogens. Used in combination
with disinfection and sanitation practices, biosecurity can reduce pathogens
to non-infectious levels. The implementation of biosecurity practices
can control pathogens and their vectors and, as a result, will reduce
economic losses caused by disease outbreaks or transmission of food-borne
illnesses.
Biosecurity should be addressed within each production unit to improve
animal health and minimize foodborne contamination. Key areas such as
sanitation, traffic control, and proper isolation and testing of newly
introduced replacement animals should be addressed in order to prevent
the introduction and/or spread of disease to the livestock in the production
unit. Implementation should: 1) focus on the disease, 2) evaluate risk
factors, and 3) determine and establish realistic intervention strategies.
In order to effectively address biosecurity for prevention of animal
disease in a production unit, specific disease targets need to be defined.
Producers should outline the diseases of concern, their current herd
status, herd goals for prevention and/or control of disease, and management
capabilities. Producers must also consider biosecurity issues between
production units, such as feedlot to feedlot contamination. Transportation
of contamination can be via clothing (e.g., footwear) and vehicles or
other equipment that is used in multiple locations within the production
system.
Biosecurity is related to food safety issues. Biosecurity will assist
in the reduction in the occurrence and treatment of infectious diseases,
control diseases with possible human health implications, and control
infectious agents of concern to human health (e.g., E. coli O157:H7
or Salmonella). Biosecurity is a portion of SSQA that benefits producers
and consumers alike.
SCRAPIE
ERADICATION
Another health program that is mandatory for sheep producers is the
Scrapie Eradication State-Federal-Industry Uniform Methods and Rules
(UMR). Scrapie Eradication Uniform Methods and Rules are cooperative
procedures and standards adopted by APHIS and Constituent States for
controlling and eradicating scrapie. The UMR provides the minimum program
standards and procedures for the Cooperative State-Federal-Industry
Scrapie Program. They are set up to prevent, monitor, control, and eradicate
Scrapie disease from domestic sheep and goat flocks, and for maintenance
of State status in the USDA's Scrapie Eradication Program. For more
information about scrapie, contact your State Scrapie Certification
Board or USDA, APHIS, Veterinary Services, 4700 River Road, Riverdale,
MD 20737.
MICROBIAL
CONTAMINATION
Microbial contamination includes pathogens that can be transmitted to
consumers, via carcasses, and cause foodborne illness. There is research
that indicates that there are control points within a production system
to decrease the amount of microbial contamination from a source to the
sheep in the production unit. Producers should take measures to control
contamination of sheep resulting from birds, water, feed and feedbunks.
Control procedures should be outlined and documented to verify that
preventive measures have been taken. Research conducted by Colorado
State University [Duffy et al., 2000, Dairy, Food and Environmental
Sanitation, 20(10):753-762] outlined pre-harvest management practices
that impact microbial contamination of lamb carcasses including shearing,
bedding and pen conditions.
FLUID
LEAKAGE
Leakage of fluids from transmissions and transformers poses a potential
problem. Both types of fluid contain PCBs, which can leave a violative
residue in slaughtered animals. Avoid installing transformers near grain
or forage storage areas and move, if possible, existing transformers
from storage areas. Other sources of potential residues could occur
from inappropriate storage of lead batteries, paint, solvents or petroleum
wastes.
PEST
CONTROL
Control of rodents and birds is a continuous battle in most lamb feedlots.
These pests transmit disease and cause damage to equipment, including
sensitive electrical connections. Control measures should consider any
possible residue as well as animal and human safety potential.
WATER CONTAMINATION
Protection of the water supply from contamination must be a high priority
of every sheep operation. Clean-water dispensers should be provided to
sheep at all times. Everyone in the sheep operation must be on constant
alert for practices that could cause contamination of the water supply
or the water dispensers. If anyone suspects they have discovered a water
supply contamination source, it must be reported to the manager as soon
as possible and action must be taken.
WOOL CONTAMINATION
Urine and Manure Contamination
Natural contamination can be minimized with good sanitation practices.
Examples include crutching (shearing around the tail and rear legs of
the sheep), and shearing lambs as they enter the feedlot. Because urine
and manure cause staining, crutching and shearing increase the value of
wool and pelts. Parts of the fleece that are heavily soiled should be
removed (skirted) at shearing time.
Insecticides
Treatment for external parasites is often performed at shearing time.
Keds, ticks and lice can cause damage to the pelt and wool, reducing their
value. However, the improper use of chemicals for the control of these
parasites can represent a risk for consumers. Lanolin (wool grease) is
extracted during the wool scouring process and is used for many cosmetic
products, medicated ointments and eye medications.
SANITATION
The accumulation of dirt, mud and manure on the fleece can result in
contamination of the carcass at slaughter during pelt removal. Proper
sanitation is important for several reasons.
• It reduces disease. Fewer disease problems result in lower production
costs.
• Since healthy sheep require fewer drugs, the risk of residues
occurring in meat and milk are reduced.
• Proper sanitation reduces likelihood of bacterial contamination
of consumer products. Food poisoning from bacteria such as E. coli O157:H7
and Salmonella cause significant illness, and sometimes death, in humans
every year. Pathogen reduction or the elimination of these disease-causing
organisms from the food supply should be a primary goal.
• Bacteria in meat or milk products cause rapid spoiling. These
organisms are frequently found in the feces of livestock. Milk from
dairy sheep can pick up unacceptable odors and flavors from being exposed
to an unsanitary environment. It is very important that every measure
be taken to keep livestock facilities clean and reduce the potential
for transmission of pathogens.
Sanitation includes first cleaning, and then disinfection. The most
important aspect of sanitation in livestock facilities is the removal
of manure. Regular removal of manure prevents the build-up of bacteria
and parasites in the environment.
Wet conditions also contribute to poor sanitation and disease problems.
Bacteria grow rapidly in standing water and mud. When sheep are confined,
it is important to provide dry areas in which they can bed down. This
can be accomplished by providing good drainage, by furnishing bedding
or by creating a raised mound. Feeding and watering areas also should
be well drained.
Bacteria transferred from the pelt to the carcass can contaminate the
meat. Soiled fleeces on the dairy sheep can contaminate milk at milking
time. Manure and mud on wool or pelts reduces the value of these products
by limiting options for the processor. Freight cost and the cost of
cleaning the pelts also are increased. During the wet seasons of the
year, feedlot lambs should be shorn in order to prevent the collection
of mud and manure their wool. This, in addition to the use of clean,
well-drained facilities and plenty of bedding, will reduce disease and
contamination problems.
Disinfection involves the use of chemicals to kill disease-causing organisms
on equipment and facilities. Commercial disinfectants or a dilute bleach
solution can be used. Disinfectants are inactivated by manure and other
organic materials. Therefore, it is important to do a thorough job of
physical cleaning before using a disinfectant. Always follow label directions
for exposure time and rinsing instructions when using disinfectants.
Sheep are often exposed to contagious diseases when their feed or water
is contaminated with manure, nasal secretions, or uterine discharges.
Feeders and waterers should be cleaned and disinfected regularly to
prevent the build-up of disease causing agents. Sick animals should
be kept separate to protect the remainder of the flock from contamination
of the feed and water supply.
Milking
Hygiene
Each state has standards for production of manufacturing grade milk.
The Pasteurized Milk Ordinance (PMO) contains guidelines for Grade A
milk production that are set by the Interstate Milk Shippers (IMS).
Bacteria counts in milk are directly linked to parlor hygiene and milk
handling. Milk should be checked for abnormalities in color, odor or
texture prior to putting on the milking machine. Ewes with abnormal
milk should be milked last and the milk discarded.
For proper milking hygiene:
1. Clip wool from the udder.
2. Clean the teats.
3. Dry the teats prior to milking.
4. Attach teat cups with minimal suction loss.
5. Adjust the milk claw to completely milk out each ewe.
6. Use teat dip after milking.
A treatment plan for ewes with mastitis should be developed with the
help of your veterinarian. This process may include bacterial culturing
and sensitivity testing of milk samples. Information about sanitation
procedures and causative organisms can be used to develop a treatment
protocol.
Sanitizer residues can cause difficulties in the use of milk for cheese
production. Because of the small volume of milk produced by a ewe, even
a trace amount of chemical residue can contaminate the product. Label
instructions for the use of sanitizers should be strictly followed.
Chlorine, iodine and other agents that break down quickly are preferred.
Ammonium chloride compounds are persistent and should not be used.
Sheep milk may be frozen and processed later. It must be cooled according
to state dairy standards, usually to less than 50°F within two hours
after milking. If it is to be frozen, it should be frozen as quickly
as possible and stored at a temperature of less than 0°F.
Caseous
Lymphadenitis
Caseous lymphadentis (CLA) is a common disease of sheep that is directly
related to sanitation. This disease has a significant economic impact
on the sheep industry. It results in the formation of abscesses or boils
and is the leading cause of ewe carcass condemnation in the US. Abscesses
also damage the pelt, reducing its value. Affected flocks have a high
culling rate.
Caseous lymphadentis is caused by bacteria that reproduce inside the
abscess. When the abscess ruptures, the bacteria are released, contaminating
the environment. They can survive in soil and bedding, and on the surface
of feeders for several months. During this time they can infect other
sheep. The bacteria can penetrate normal skin, but more commonly infect
an animal through cuts, scratches and other wounds. Range sheep are
most often infected at shearing time, while farm-flock sheep can become
infected from contaminated feeders and housing as well as from shearing.
The incidence of CLA in affected flocks can be reduced with proper control
methods and good sanitation.
1. Cull or isolate affected animals before abscesses rupture.
2. Disinfect equipment, facilities, or surfaces that come into
contact with pus.
3. Disinfect skin wounds to prevent infection.
4. Shear sheep in the order of youngest to oldest; shear sheep
with swellings or abscesses last.
5. Disinfect shearing equipment by dipping the comb and cutter,
between sheep, into a disinfectant.
6. Maintain equipment and facilities in good repair to prevent
sharp objects from causing injury and abscess rupture and spread.
7. Control ectoparasites as scratching creates breaks in the
skin making it more susceptible to infection.
8. Vaccinate the entire flock to reduce the rate of CLA infection
by boosting flock immunity.
Good sanitation is essential in the control of disease. It prevents
disease transmission within the flock, reduces the need for drug use,
and reduces the contamination of food products. In addition, clean sheep
yield clean, high quality wool and pelts of maximum value.
Summary of Step 3 Criteria
That Can Be Achieved By Use Of Objectives and Procedures
3.1 Maintain records of pesticides (herbicides, insecticides,
etc.) used that could cause a violative residue in grazing sheep or
feedlot sheep.
3.2 Use medicated feed additives in accordance with the FDA Good
Manufacturing Practices (GMP) regulations. (These include a formula
record of all medicated feed rations produced, and production records
of all batches of feed produced which contain medicated feed additives.
Production records must include additive used, date run, ration name
or number, amount produced and the earliest date animal(s) could clear
withdrawal period.)
3.3 Follow the Judicious Antibiotic Use Guidelines of the Academy
of Veterinary Consultants to minimize the development of antimicrobial/antibiotic
resistance in human pathogens.
3.4 Use all pesticides according to FDA/EPA label directions.
Record all use of pesticides (such as pour-ons or injectables) including
product identification, lot/serial number of the product, date used,
amount used, and withdrawal time.
3.5 Address biosecurity issues to control animal health and foodborne
contamination.
3.6 Eliminate contamination with foreign material (i.e. needles,
birdshot, etc.).
3.7 Shear lambs to maintain shorter and cleaner fleeces.
3.8 Maintain a sanitary environment as mud results in decreased
performance, increased stress and immune compromised sheep.
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