Physical characteristics of the bovine teat canal and their influence on susceptibility to streptococcal infection

Abstract

SummaryPhysical characteristics of the bovine teat canal were examined for their influence on susceptibility to intramammary infection. All quarters of 18 cows were inoculated with 2 × 105 cfu Streptococcus agalactiae (Trial 1) and 20 cows with 105 cfu Str. Uberis (Trial 2) 3–4 mm into the teat canal every 3 d for 12 d. Incidence of quarter infection was similar for both pathogens, 30/72 (42%) in Trial 1 and 32/80 (40%) in Trial 2. Logistic regression analysis showed that probability of infection by Str. Agalactiae increased significantly with an increase in quarter peak flow rate (P < 0·05) whereas probability of infection increased for Str. Uberis with a decrease in teat canal length (P < 0·05). A significantly higher (P < 0·001) incidence of infection by Str. Uberis was observed in quarters that contained a low wet weight (< 1·8 mg) of removable keratin compared with those that contained > 1·8 mg keratin, but there was no correlation between weight of keratin and length of the teat canal. Infections by Str. Uberis took significantly less (P < 0·05) time to show a rise in somatic cell count above 7·5 × 105 cells/ml than Str. agalactiae. The results provide evidence that these pathogens use different mechanisms to pass through the teat canal.

Estimates of genetic parameters for milkability from automatic milking

“…! The genetic correlation coefficient between milk yield and average milk flow is positive indicating that further selection for higher milk yield might result in a deterioration of udder health, as a higher milk flow is associated with increased problems in terms of udder health (Grindal and Hillerton, 1991;Lacy-Hulbert and Hillerton, 1995;Boettcher et al, 1998;Zwald et al, 2005). Thus, in the future, the relative breeding value for milkability (average milk flow) could be involved in the selection.…”

“…In an automatic milking system, the reduction of total milking time per milking per cow means an increase in the capacity of the automatic milking system (Prins et al, 2002). But higher milk flow is also associated with an increase in problems in terms of udder health (Grindal and Hillerton, 1991;Lacy-Hulbert and Hillerton, 1995;Boettcher et al, 1998;Zwald et al, 2005). This claim can be supported because the milk flow rate is linked to the patency of the teat canal (Persson Waller et al, 2003), i.e.…”

Ultrasonographic measurement of the bovine teat: breed differences, and the significance of the measurements for udder health

“…Natural defence mechanisms against udder pathogens are the teat and teat connective tissue. The influence of teat canal length and diameter on the occurrence of mastitis by bacterial pathogens has been examined (McDonald, 1975;Grindal et al 1991;Scherzer, 1992;Seyfried, 1992;Hamana et al 1994 ;Lacy-Hulbert & Hillerton, 1995). Grindal et al (1991) could find no significant influence of teat canal length on new infection McDonald (1975) and Hamana et al (1994) but, additionally, they found significant differences in teat canal diameter between healthy and infected udder quarters.…”

Milk Yield and Composition, Nutrition, Body Conformation Traits, Body Condition Scores, Fertility and Diseases in High‐Yielding Dairy Cows – Part 1

“…Nevertheless, factors other than high milk yields per se contribute to elevated SCC. Of these factors, short teat channel lengths and associated high peak milk flow rates are considered to be of primary importance (Lacy‐Hulbert and Hillerton, 1995) and there is a positive genetic correlation between milk yields and peak milk flow rates (Petersen et al., 1986). Because peak milk flow rates of individual quarters in high‐yielding cows were not different from those in cows with average yields (Wellnitz et al., 1999), this possibly explained the absence of differences in SCC between HC and CC cows.…”