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Assessing the correlation between teat end scores and presence of mastitis in lactating Holstein cows
Mastitis is an inflammation of the mammary gland caused by bacteria that affects 1 in every 3 cows and costs the producer an average of $180/cow/year. Penetration of bacteria into the teat canal causing mastitic infections may be enhanced by hyperkeratosis, a thickening of the teat canal keratin, which provides a breeding ground for bacteria. The objective of this project was to determine if a correlation exists between elevated teat end scores (degree of hyperkeratosis) and presence of mastitis as indicated by elevated somatic cell counts (SCC). Purebred Holstein cows (n=30) were assesssed and sampled between 30 and 100 days in milk. Each animal was given a teat end score (TES) at sampling on a scale of 1 (smooth) to 4 (rough ring) according to level of severity, and teat canal swabs as well as milk samples were collected aseptically from each quarter for microbiological examination to determine infection status and if infected, the pathogen(s) present. All milk samples were further evaluated for SCC using a DeLaval Cell Counter. The association of TES, infection status, and SCC was analyzed using the CORR procedure of SAS. A strong positive correlation was seen between level of infection and SCC for each quarter (P=0.001) and for TES and age of the cow (P=0.001). The average TES for uninfected quarters was 2.00, while the average TES for infected quarters was 2.42. However, there was no correlation between presence of infection and TES (P=0.444) or SCC and TES (P=0.439). When infected quarters were compared for pathogen and average TES, the following observations were made: CNS (TES=1.9), Streptococcus (TES=2.), Prototheca (TES=2.0), S. aureus (TES=2.6), mold (TES=3.0) and E. coli(TES=3.0). While no correlation was found for the presence of infection and teat end scores, the observation regarding the presence of specific mastitis causing bacteria and elevated teat end scores is an area for future investigation. This observation also suggests that teat end hyperkeratosis is associated with presence of mastitis caused by certain pathogens and that management practices should be in place to promote healthy teat ends for decreased mastitis incidence rates.
Keywords:
Hyperkeratosis, Somatic Cell Count, Mastitis Pathogens