Premilking teat sanitation reduces the load of bacteria on teat skin before milking and it is a fundamental practice used to ensure collection of high-quality milk. The objective of this study was to compare reduction in bacterial populations of teat skin after premilking preparation using either predipping with 0.5% iodine followed by drying (conventional; CONV) or using a semiautomated teat scrubber that uses chlorine dioxide (TS; FutureCow, Longwood, FL). Ten farms currently using a commercial teat scrubber system were enrolled. Cows (n=40 per farm) were assigned to CONV (n=198) or TS (n=196) premilking udder preparation. Teat skin swabs were collected before and after udder preparation and analyzed for total bacterial count (TBC), Streptococcus spp., Staphylococcus spp., and gram-negative bacteria (GNB). Reduction (RED) of each bacterial group was defined as the difference in the number of bacteria measured before and after udder preparation. Before udder preparation, Staphylococcus spp. (15,036 cfu/mL) and Streptococcus spp. (12,621 cfu/mL) were the most numerous microflora. Gram-negative bacteria were less numerous (1,538 cfu/mL). A significant treatment by farm interaction was identified for RED of all bacterial counts. Compared with teats prepared using TS, teats prepared using CONV preparation had greater RED of TBC on 3 farms, of Streptococcus spp. on 2 farms, and of Staphylococcus spp. on 1 farm. On all other farms, RED in TBC, Streptococcus spp., and Staphylococcus spp. did not differ based on teat preparation method. Use of TS resulted in greater RED of GNB of teats on 3 farms, but RED in GNB was greater for teats cleaned by CONV on 1 farm; for the other 6 farms, RED of GNB did not differ between methods. For all bacterial counts, an effect of chlorine dioxide concentration used in the teat scrubber was observed. Results from this study suggest both CONV and TS can effectively reduce bacterial counts, but farm conditions and management practices can have a significant effect on the effectiveness of teat disinfection.

The primary objective of this study was to describe and compare anatomical characteristics of teats before and after machine milking adjusted for parity and teat location (front versus rear). The second objective was to determine if selected milking and anatomical characteristics of teats were associated with occurrence of clinical mastitis. To address objective 1, a cross-sectional study was done to describe and compare teat dimensions before and after milking (n=1,751 teats from 445 cows). To fulfill objective 2, a case-control study was performed. Quarters having their first case of clinical mastitis in the current lactation from 2 mo before to 2 mo after the day the teats were measured were selected as cases (n=47), provided no other quarters from that cow were affected by clinical mastitis at that time. Three controls (n=141) were matched with each case; these were selected from quarters that did not experience any case of clinical mastitis during their current lactation. A conditional logistic regression model was used to determine associations between teat dimensions and occurrence of clinical mastitis. Primiparous and multiparous Holstein cows were enrolled in both studies. As compared with premilking dimensions, postmilking teats were longer and narrower at the barrel and the apex. Significant interactions between teat position and parity were identified for premilking teat length and diameter of the teat barrel. Premilking, teats were longer and wider with increasing parity. Front teats were longer and wider than rear teats premilking. Also during premilking, differences between the front and rear teat were less at increasing parity. Teat apex diameter was greater for premilking teats of cows in parity ≥3 and the apexes of front teats were wider than those of rear teats. Teats enrolled in the case-control study had twice as many clinical mastitis cases in front quarters compared with rear quarters. Premilking diameter of the teat apex was positively associated with risk of clinical mastitis (odds ratio=1.20 per 1-mm increase in the diameter of the apex of the teat, 95% confidence interval=1.05-1.37). Milking machine-related changes in teat dimensions had no association with occurrence of clinical mastitis.

Mastitis occurs after bacteria successfully traverse the teat orifice and cause an intramammary infection. Anatomical characteristics of the teat are potential risk factors for infection. The objective of this study was to identify potential associations between anatomical characteristics of teats and quarter-level somatic cell count (QSCC) from cows on larger dairy farms in Wisconsin. Teat dimensions (length and diameter at the teat barrel and apex) were measured, and hyperkeratosis scores were assessed for 3,713 quarters of 959 cows on 9 dairy farms. The SCC of quarter milk samples obtained from those teats was determined. Multivariate models were used to determine associations of teat anatomical characteristics with QSCC. Subclinical mastitis was defined as a quarter milk sample with SCC of >150,000 cells/mL. Teat dimensions and milk components varied among farms. In the group of farms enrolled in this study, prevalence of subclinical mastitis in mammary gland quarters ranged from 13.6 to 28.9%. An interaction of teat apex diameter and quarter position (front or rear) was identified for QSCC. For both front and rear quarters, a tendency existed for narrower teat barrels to be associated with increased QSCC. However, for front quarters only, greater diameter of the teat apex was associated with increased QSCC. Teat shape (square or triangular teats) was not associated with QSCC. Milk samples obtained from teats with hyperkeratosis scores of very rough had greater QSCC compared with milk samples obtained from teats with hyperkeratosis scores of normal, smooth ring, or rough ring.