Heifer Mastitis at Calving
Dairy Pipeline: September 1997
Extension Dairy Scientist, Milk Quality and Milking Management
In reviewing the State average DHI somatic cell counts for the past 3 years, the average SCC for first calf heifers during early lactation has increased in late summer and fall. The situation may be worse than indicated by DHI SCC. Many intramammary infections in heifers at calving are caused by environmental streptococci, which are short duration and, consequently, elevated SCC may not be present on test day. In one study involving 28 herds in California, Washington, Vermont, and Louisiana, within four days of calving, heifers were found to have the following infections: Staphylococcus aureus, 2.8%, Environmental streptococci and coliforms, 7.7%, and staphylococcus species, 21.8%. Infections increased during the summer. In Tennessee, 90% of the Jersey heifers in an untreated group were infected in 62% of quarters at 7 days prior to expected calving, which decreased to 78% of heifers infected in 44% of quarters 3 days after calving. Over 50% of the infections were pathogens generally not considered as major causes of mastitis, but they can elevate somatic cell counts, sometimes become clinical, and only 27% were eliminated spontaneously (without treatment). More important--7.5% of quarters were infected by Staphylococcus aureus, environmental streptococci, and other major pathogens. Two groups of Jersey heifers received lactating cow antibiotic treatments of sodium cloxacillin or cephapirin sodium at 7 days prior to expected calving. Cephapirin treatment cured 97% of Staphylococcus species and 100% of the nine major pathogen infections. Cloxacillin cured 84% of Staphylococcus species and 77% of major pathogen infections. A precaution for Cloxacillin treatment-28% of heifers were antibiotic positive at 3 days after calving. All were antibiotic negative at next test (10 days after calving). Ohio State researchers report thatonly 50% of environmental streptococci infections are cured without treatment, 50% of environmental infections cause clinical mastitis during lactation, and 40-45% of clincal cases are caused by environmental pathogens. In the University of Kentucky herd, although the prevalence of Staphylococcus aureus infections decreased from 7.6% of heifers at calving to 3.5% for the first four weeks of lactation, these heifers were a potential source of S. aureus infection for the rest of the herd. Dr. Steve Nickerson, Louisiana, reported that first lactation infections occur in many herds and that 37% are caused by S. aureus with an 18% decrease in milk production. These bacteria colonize the teat canal causing the release of toxins and chemotactic agents that trigger an increase in somatic cell counts. In his studies, a dry cow antibiotic was given by partial insertion at 60 days prior to calculated calving date (I guess you can't use a herd bull to breed 'em) and overall incidence of infection was reduced 60% and S. aureus infections decreased 90%. All milk samples were negative for antibiotic residues at 5 days after calving. Herds may wish to consider antibiotic treatment of bred heifers, either with dry cow antibiotic at 60 days before expected calving or lactating cow treatment at 7 days prior to expected calving. Treatment tubes should only be partially inserted into the teat opening but not until the teat has been washed and dried, tipped in teat dip, and scrubbed with alcohol disinfectant. Teats must be dipped after treatment and heifers placed in a clean and dry environment.