TITLE: Research on a New Barrier Teat Dip

CONTACT: Stephen C. Nickerson, Hill Farm Research Station, (318)927-9654 or Bill Owens, 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 (SCC). 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 rainy 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 prior to as well as after milking, a product is needed to form a thin, impregnable, bactericidal film over the teat end after machine removal, which will seal the teat orifice and provide prolonged antibacterial activity, especially under wet, muddy conditions.

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 additional 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 United States dairies, as reflected in the SCC, is quite high compared with national figures, which indicate that 85% of dairies are producing milk with SCC of less than 400,000/ml. In Louisiana, approximately 50% of dairies are producing milk with SCC of less than 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: DAIRY

TITLE: New Somatic Cell Count Limits

CONTACT: Stephen C. Nickerson, Hill Farm Research Station, (318)927-9654 or Richard F. Graham, Dept. of Health & Hospitals, (225)765-5022.

TAKE HOME MESSAGE: In the not too distant future, quality standards for raw milk may well be set at a higher level, and Louisiana dairymen will need to lower bulk tank somatic cell counts (SCC) to stay "in grade" with health department standards. Although this lowering of the SCC seems to be a hardship to producers, it will inevitably increase profits to their operations by lowering the level of mastitis in their herds. Thus, lowering the upper SCC limit for acceptable raw milk will, in the long run, have a positive effect on the Louisiana dairy industry.

PROBLEM / TOPIC: Bovine mastitis is a continuing problem for the dairy industry by lowering both milk yield and milk quality. In fact, mastitis is the most important disease of dairy cattle, resulting in losses of approximately 2 billion dollars to the United States dairy industry through lowered milk production, discarding of abnormal milk, culling of chronically infected cows, and costs of veterinary intervention, antibiotics, and extra labor. The SCC is used as a measure of the level of mastitis in a herd. Currently, the upper limit for herd bulk milk SCC is 750,000/ml; however, in May of 2001, proposals will be submitted to the National Committee on Interstate Milk Shipments that will advocate lowering the present limit to 400,000/ml sequentially over the next few years. In Louisiana, approximately 50% of herds are producing milk with a SCC below 400,000/ml. It is obvious that many producers in this state will need to tighten up their mastitis control measures in order to lower the herd SCC.

ACTION: A comprehensive plan of mastitis control has been developed to reduce the herd level of mastitis and lower SCC. Although this plan has been in place for several years, many producers need to updated on a regular basis to continue to improve their mastitis control practices. In Louisiana, elevated SCC are mainly caused by the contagious bacteria: Staphylococcusaureus and Streptococcus agalactiae, as well as the environmental bacteria: Escherichia coli Streptococcus uberis. The best way to control mastitis caused by all of these bacteria is through preventative methods. Cows are exposed to the contagious bacteria during the process of milking, and postmilking teat dipping with an approved product is the best method for preventing new infections with these organisms. During the intermilking period, cows are exposed to the environmental bacteria, and the best way to prevent new infections with these organisms is through the practice of predipping. If prevention fails, and clinical cases of mastitis occur, infected quarters should be treated promptly with commercially available mastitis tubes. The best cure rate is obtained with dry cow therapy in which all four quarters are infused to treat infected quarters as well as to prevent new infections in uninfected quarters.

IMPACT: By conscientious application of the comprehensive control plan recommended above, it will be possible for dairymen to lower herd SCC. Initiation should begin immediately in order to prepare for the possible reduction in SCC limit, which could take place as early as 2002. At current cell counts of approximately 500,000/ml, the average Louisiana dairy herd of 70 cows is losing $18,000/year due to mastitis. Thus, by reducing the level of mastitis dairymen are lowering the herd somatic cell count, increasing milk yield, and maximizing profits.

Revised: September 22, 2000