Association of anatomical characteristics of teats with quarter-level somatic cell count

Abstract

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.

Anatomical characteristics of teats and premilking bacterial counts of teat skin swabs of primiparous cows exposed to different types of bedding

“…The mean (SE) teat length [42.6 (0.53) mm], teat barrel diameter [21.4 (0.19) mm], and width of teat apex [19.2 (0.13) mm] measured in the current study (Table 1) are similar to data of primiparous cows previously obtained by our research team (Guarin et al, 2017) in a larger cross-sectional study. In that study (Guarin et al, 2017), teats of primiparous cows (n = 618) had mean (SE) length of 42.8 (0.30) mm, barrel diameter of 22.7 (0.10) mm, and teat apex diameter of 19.3 (0.8) mm. As compared with the previous cross-sectional study (Guarin et al, 2017), similar dimensions of front and rear teats were also separately observed, although the diameter of both front and rear teat barrels of cows enrolled in the previous cross sectional study appeared to be about 1 to 1.5 mm wider.…”

“…These results agree with previous results for teat length but differ from our previous results for teat barrel diameter (Guarín and Ruegg, 2016). The mean (SE) teat length [42.6 (0.53) mm], teat barrel diameter [21.4 (0.19) mm], and width of teat apex [19.2 (0.13) mm] measured in the current study (Table 1) are similar to data of primiparous cows previously obtained by our research team (Guarin et al, 2017) in a larger cross-sectional study. In that study (Guarin et al, 2017), teats of primiparous cows (n = 618) had mean (SE) length of 42.8 (0.30) mm, barrel diameter of 22.7 (0.10) mm, and teat apex diameter of 19.3 (0.8) mm.…”

“…No association was found between teat HK score and quarter position (χ 2 = 0.656) and no association was observed between HK scores and teat skin bacterial count (P = 0.757), but the prevalence of undesirable scores was very low. Previous work by our group (Guarin et al, 2017), which included a greater number of herds and cows, indicated that teats with scores of VR are associated with greater quarter SCC. Neijenhuis et al (2001a) studied 15 farms in the Netherlands consisting of 2,157 cows and determined that cows with CM had greater HK scores than herd mates and the association of HK and CM varied among pathogens.…”

“…In that study (Guarin et al, 2017), teats of primiparous cows (n = 618) had mean (SE) length of 42.8 (0.30) mm, barrel diameter of 22.7 (0.10) mm, and teat apex diameter of 19.3 (0.8) mm. As compared with the previous cross-sectional study (Guarin et al, 2017), similar dimensions of front and rear teats were also separately observed, although the diameter of both front and rear teat barrels of cows enrolled in the previous cross sectional study appeared to be about 1 to 1.5 mm wider.…”

“…In a recent case-control study, we demonstrated that increased diameter of the teat apexes of front teats was associated with increased risk of clinical mastitis (Guarín and Ruegg, 2016). Likewise, for front (but not rear) teats, we recently observed that greater diameter of the teat apexes was associated with increased SCC (Guarin et al, 2017). These associations may indicate that front teats with wider apexes have reduced ability to resist IMI caused by opportunistic bacteria and emphasize the importance of understanding the magnitude of bacterial exposure based on bedding type.…”