COMMODITY: DAIRY

TITLE: Horn Flies and Mastitis in Dairy Heifers

CONTACT: Dr. Bill Owens, Microbiologist, Hill Farm Research Station (318) 927-9654

TAKE HOME MESSAGE: Recent research has shown that the horn fly can and does transmit mastitis among dairy and beef heifers. As fly numbers increase to between 50 and 100 flies per animal in the late spring, horn flies attack the teat ends of heifer mammary glands, causing scab formation and intramammary infection (IMI). Left unchecked and untreated, IMI can result in permanent damage to developing heifer mammary gland tissue, resulting in chronic infections and lost milk production when heifers mature and enter the lactating herd. Aggressive fly control for heifers is warranted as fly numbers increase in late spring and early summer.

PROBLEM/TOPIC: Dairy heifers are the life blood of the dairy. Without a constant supply of top quality replacement heifers, the dairy can not continue to operate effectively. In recent years, both dairy and beef heifers have been shown to be at risk for developing mastitis. Research had shown that as high as 90% of heifers can harbor mastitis organisms in their mammary glands prior to freshening. Staphylococcus aureus, a major mastitis pathogen, is among the organisms found in heifers and can cause permanent damage to developing mammary tissue. A program of mastitis control and therapy is needed that is tailored specifically for dairy heifers and their special needs.
 
ACTION: Studies at the Hill Farm Research Station have demonstrated the existence of mastitis in heifers, and therapeutic studies have shown that those infections can be treated effectively with antibiotics in the third trimester of pregnancy with dry cow antibiotic products. However, the ideal situation is to prevent infection so that therapy can be avoided. Previous studies demonstrated that horn flies were capable of causing these infections, and a trial was conducted to determine if treatment with an insect growth regulator (IGR) product could control flies sufficiently to be effective. Dairy heifers were divided into two groups with one receiving an IGR containing mineral, while the other group served as an untreated control. Results indicated that the IGR product could not suppress horn flies sufficiently to prevent scab formation and S. aureus mastitis in heifers.
 
IMPACT: Studies on heifer mastitis have shown this to be a significant problem for the Louisiana dairy industry and one that needs additional research. Therapy studies have provided vital information for treating heifer mastitis with antibiotics, and now studies on the causes of this disease will lead to control measures. The discovery of the link between horn flies and S. aureus mastitis gives the dairy farmers a key area on which to focus control efforts. When horn fly numbers increase above 50 to 100 per animal, dairy farmers need to begin aggressive fly control measures to help protect their valuable heifers from this problem. This will also require that dairy farmers keep a closer eye on heifers and flies. Horn fly numbers can increase dramatically in just a few days, and damage from fly bites can occur quickly. Heifers will need close observation for signs of fly problems so control measures can be implemented. Fly numbers of 50 to 100 per animal were sufficient to cause a problem, and the IGR product could not suppress flies below this level.
 
 

   
COMMODITY: DAIRY
 
TITLE: Teat Dipping: Number One Management Tool to Prevent Mastitis and Lower SCC

CONTACT: Dr. Stephen C. Nickerson, Lactational Physiologist, Hill Farm Research Station (318) 927-9654

TAKE HOME MESSAGE: Teat dipping of cows teats both before and after milking is the best management tool for controlling mastitis by preventing new intramammary infections and lowering somatic cell counts. The development of new teat dip products that provide both extended germicidal activity between milkings as well as barrier properties when cows are exposed to the environmental pathogens will help to reduce new mastitis cases during the warm and humid periods of the year.
 
PROBLEM / TOPIC: The rate of new intramammary infection is dependent upon the number of mastitis-causing bacteria growing at the teat end. The dipping of teats in a germicidal solution prior to milking (predipping) and after milking (postdipping) has become the most beneficial management tool for dairymen to reduce the number of bacteria on teats, and subsequently prevent these organisms from gaining access to the interior of the udder. The cow is exposed to the environmental organisms such as Streptococcus uberis and Escherichia coli during the intermilking period when she is exposed to mud, manure, and bedding materials. Although teat germicides are effective in removing the vast majority of mastitis-causing bacteria immediately prior to as well as after milking, a product is needed to form a thin, impregnable, bactericidal film over the teat end immediately after machine removal, which will seal the teat orifice and provide prolonged antibacterial activity.
 
ACTION: Laboratory and field experiments were initiated to develop an antibacterial surgical shield used in human medicine into a product that could serve as a germicidal barrier for cows teats during lactation. Initially, various formulations of the product were evaluated in vitro for germicidal activity against common mastitis-causing bacteria. The most efficacious formulation was then tested on cows' teats to determine efficacy in killing bacteria on teat skin. A variety of dyes were added and the one providing most visibility was chosen to evaluate for persistence on teat skin as well as skin irritability. A formulation was also developed for nonlactating cows to be applied to teats at dry-off immediately after the infusion of nonlactating cow antibiotics as well as once during the prepartum period approximately 1 week prior to calving. The purpose of this dry period barrier was to augment the beneficial effect of dry cow therapy and to provide protection during the immediate prepartum period when the udder is susceptible to infection with environmental organisms.
 
IMPACT: Mastitis is the most important dairy cattle disease because it drastically reduces milk production. It is estimated that this disease causes production losses approaching $12 million in the state of Louisiana alone. The level of mastitis in southeast US dairies, as reflected in somatic cell counts (SCC), is quite high compared with national figures, which indicate that 85% of dairies are producing milk with SCC<400,000/ml. In Louisiana, approximately 50% of dairies are producing milk with SCC<400,000/ml. At present, the legal SCC limit for shipping milk is 750,000/ml; however, regulatory agencies may reduce this limit to 400,000/ml by 2003. Teat dipping is the most useful tool for dairymen to use for controlling the devastating losses caused by mastitis, and improved products are needed to further reduce the infection level in Louisiana dairies. It is believed that the development of novel germicidal barrier products will provide further control against environmental pathogens and help dairymen lower SCC in order to comply with future milk quality standards.
 

COMMODITY: WASTE WATER LAGOONS

TITLE: Lagoons for Dairy, Swine, Alligator, and Poultry (Egg) Waste and Waste Water

CONTACT: Mr. Bill Branch, Specialist, Cooperative Extension Service (225) 388-6998

TAKE HOME MESSAGE: Lagoons or oxidation ponds are frequently used for storage and treatment of animal waste and waste water from animal feeding operations prior to land application. Installation cost for a 120 cow dairy herd may be $10,000-$12,000. Operating and maintenance cost may average $1,000-$2,000 per year including sludge removal every 4-5 years at a cost of $3,000-$5,000.
 
PROBLEM/TOPIC: The 1972 Amendments to the Federal Water Pollution Control Act (commonly called the Clean Water Act) identified Confined Animal Feeding Operations (CAFOs) as a point source of water pollution requiring a permit and prohibiting discharge of waste water except in the event of a 24 hour, 25 year storm (in Louisiana this varies from 9-12 inches of rainfall in 24 hours). Louisiana established a General Permit for CAFOs requiring "no discharge systems" in 1988 and EPA established a general permit requiring no discharge in 1993. The President's Clean Water Act prohibits waste water discharges from CAFOs and AFOs (smaller CAFOs). DEQ issued nearly 100 Administrative Orders, Compliance Orders, or Notices of Violation to dairy farmers in 1998. Producers who refuse to install no-discharge systems are subject to fines.
 
ACTION: (1) Soil probes are used to determine if existing clays are adequate to minimize leaking. Marginal clays can be recompacted. Acceptable clay can be hauled into site and compacted. Artificial liners can be used. Leaking to ground water is a problem that must be dealt with during construction to insure than an adequate clay liner or other liner exists and remains intact. (2) Irrigation systems can be designed and operated to remove excess water for irrigation. Avoiding a discharge is a problem that must be managed during operation by timely irrigation. (3) Removal of sludge from a dairy or poultry lagoon is a problem that can be minimized by use of a sediment trap or solids separation equipment. Sediment traps can be designed, constructed, and operated to minimize rate of accumulation of sludge in dairy or poultry lagoons. Solids can be applied to land and recycled through other applications. (4) Removal of sludge is accomplished with a dredge or agitator/pumping equipment. Dredges are available to remove sludge with minimal disturbance of water above sludge layer. Agitators are available to mix lagoon contents and allow irrigation pumps to remove sludge through irrigation systems.

IMPACT: Lagoons can be used to store and treat animal waste and waste water with minimal demand for labor and management, minimal leakage into the ground water and minimal runoff from irrigated fields. Lagoons should be considered as one option for managing liquid animal waste and waste water from dairy parlors and holding areas, hog and alligator barns and poultry waste from table egg production. Dry litter and manure from broiler or breeder hen operations, horse stables or any other animal feeding operation that can be removed mechanically for field application or other forms of recycling should not be stored in a lagoon.
 
 

 
 Revised: April 3, 1999