Abstract
The length of the streak canal and the area of the teat end were studied by ultrasound during the dry period in 40 Holstein-Friesian cows. In the first week, the values of these teat parameters decreased significantly (P < 0.05) and this did not change significantly until the middle of the dry period. In the last month of gestation, the length of the streak canal was significantly reduced (P < 0.05), while the area of the teat end did not decrease significantly (P > 0.05). At each of the five examination times, a very strong positive correlation (r = 0.85-0.94) was found between the two teat parameters. In healthy cows, the streak canal and the area of teat end, both of which are part of the udder's defence system, can regenerate sufficiently during the dry period, minimising the risk of contamination through the streak canal and the development of mastitis. If the regeneration of this defence system fails, the chances of infection through the streak canal increase.
Highlights
The length of the streak canal and the area of the teat end were studied by ultrasound during the dry period in 40 Holstein-Friesian cows
Compared with the last milking before the dry period, the length of the streak canal decreased from 10.8 mm to 9.9 mm within a week, this was a significant decrease of 8.3% (P = 0.002) (Fig. 3)
The results of ultrasound examination of the teat parameters in healthy cows shows that the length of the streak canal and the area of the teat end gradually increase (P < 0.05) over time during lactation in a twice-a-day milking system (Tóth et al, 2018)
Summary
The length of the streak canal and the area of the teat end were studied by ultrasound during the dry period in 40 Holstein-Friesian cows. Several teat parameters were examined by ultrasound, e.g. the length and thickness of the streak canal (Húth, 2004; Fasulkov et al, 2014; Strapák et al, 2017), the thickness of the udder wall (Stádnik et al, 2010), the area of teat end (Húth, 2004), the diameter of the pars papillaris (Stojnovič and Alagič, 2012), and the thickness of the teat (Klein et al, 2005). The purpose of this study was to determine how the length of the streak canal and the area of the teat end, which are important parts of the defence system of the udder, change during the dry period. Comalli et al (1984) examined the changes in size, length and area of the streak canal during the dry period by ultrasound. Our study was designed to determine how the teat parameters change over the entire dry period
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