Study On Influential Factors On Udder Temperature Of Dairy Cows And The Relationship Between Udder Temperature And Mastitis

This dissertation has been organized into four experiments. In experiment one, the variation of rear quarter skin temperature of dairy cows pre- and post-milking and the corresponding influential factors were studied to determine the appropriate time to measure the infrared thermography images of dairy cows. In experiment two, daily rhythms change pattern of udder skin temperarure in dairy cows and the effect of environment temperature on udder skin temperature of dairy cows were studied. In experiment three, the effect of season and parity on udder skin temperature was discussed. In experiment four, udder skin maximum temperature was considered as the udder skin temperature indicator through the analysis of the relationship between udder skin mean and maximum temperature and Somatic Cell Count(SCC). We also examined the possibility and feasibility of a method based on temperature difference between left and right quarter skin temperature to detect subclinical mastitic quarters.The variation of rear left and rear right quarter skin temperature of dairy cows pre-milking and post-milking and influential factors on it were studied in experiment one. 102 healthy Chinese Holstein dairy cows were used in this study. Rear left and rear right quarter infrared thermography images of each cow were collected 15 to 30 min prior to milking and 25 to 40 min after milking, respectively. Meanwhile, milk production and temperature and humidity in milking parlor and barn were recorded. In a thermography image, the temperature of an area of a circle of 5 cm × 5 cm above the teat base was measured. The circle was drawn by hand with the help of the camera software. The mean and maximum value in the circle was regarded as the mean and maximum temperature of udder skin, respectively. The result showed that there was no significant difference between rear left and rear right quarter skin temperature either pre- or post-milking(P>0.05). The temperature difference between left and right quarter was less than 1.0℃. Udder skin temperature after milking was more than 1.0℃ higher than that before milking regardless of rear left quarter and right quarter(P<0.05). Milk production had no correlation with rear quarter skin temperature before milking and had positive correlation with rear quarter skin temperature after milking. Milk production level had no significant effect on udder skin temperature before milking and udder skin temperature had the rising trend with the milking production increasing(P>0.05). However, milk production had significant effect on udder skin temperature after milking(P<0.05). Udder skin temperature of dairy cows with higher milk production was more than 1.0℃higher than that with lower milking production(P<0.05).Daily rhythms change pattern of udder skin temperarure in dairy cows and the effect of environment temperature on quarter skin mean temperature and maximum temperature of dairy cows were studied in experiment two. The rear left and rear right quarter infrared thermography images were collected in six consecutive days during 13 th, Aug. 2008 to 18 th, Aug. 2008 at morning milking, afternoon milking and evening milking at least 20 min before milking in the milking parlor, respectively. In a thermography image, the temperature of an area of a circle of 5 cm × 5 cm above the teat base was measured. The mean and maximum value in the circle was regarded as the mean and maximum temperature of udder skin, respectively. The result showed that udder skin mean and maximum temperature of dairy cows had significant difference in different milking time moment. Udder skin temperature at afternoon milking and evening milking were higher than that at morning milking, whereas udder skin temperature at afternoon and evening milking had no significant difference. Different environment temperature had significant effect on udder skin mean and maximum temperature of dairy cows and udder skin temperature increased as the environment temperature increased.The effect of season and parity and their interaction on udder skin temperature was studied in experiment three. Rear left and rear right quarter thermography images of 2636 healthy Chinese Holstein dairy cows with different parities were collected and udder skin surface temperature was measured. This study was conducted in spring, summer, autumn and winter. The udder thermography images of dairy cows were collected before morning milking and environment temperature and humidity in the barn were recorded simultaneously. In a thermography image, the temperature of an area of a circle of 5cm × 5cm above the teat base was measured. The mean and maximum value in the circle was regarded as the udder skin mean and maximum temperature respectively. The result showed that there was no significant difference between rear left and rear right quarter skin temperature in different seasons(P>0.05). Rear left and rear right quarter skin temperature showed symmetrical distribution. Season and parity and their interaction had significant effect on udder skin temperature of dairy cows(P<0.05). Udder skin mean temperature increased with the season changes from winter, autumn, spring to summer. Udder skin maximum temperature showed similar trendency, but the temperature change was lower than udder skin mean temperature. First parity cows showed the highest udder skin mean and maximum temperature in spring, summer and autumn. Third parity cows had the highest udder skin mean and maximum temperature in winter.The relationship between udder skin temperature and SCC was analyzed in experiment four. This study also evaluated the possibility of a detecting method for subclinical mastitis quarter based on the skin surface temperature difference between left and right quarter. Rear left and rear right quarter thermography images of 77 Chinese Holstein dairy cows were collected in the milking parlor before milking to measure the udder skin temperature. 50 mL milk of left quarter and right quarter was collected to measure SCC in milk respectively. In a thermography image, the temperature of an area of a circle of 5 cm × 5 cm above the teat base was measured. The mean and maximum value in the circle was calculated and regarded as the mean and maximum value of udder skin temperature respectively. The result showed that quarter skin mean temperature of quarters with SCC>500×103/mL was 1.53℃ higher than that of quarters with SCC<500×103/mL. Quarter skin maximum temperature of quarters with SCC>300×103/mL and SCC<500×103/mL was 1.02 ℃ higher than that of quarters with SCC<300×103/mL. Udder skin maximum temperature had strong correlation with SCC in milk(r=0.64)and udder skin mean temperature had weak correlation with SCC in milk(r=0.36). For quarters with SCC<300×103 /mL, quarter skin temperature had no correlation with SCC in milk. For quarters with SCC>300×103 /mL quarter skin mean temperature had weak correlation with SCC(r=0.39) and quarter skin maximum temperature had strong correlation with SCC(r=0.75). Udder skin maximum temperature had the higher sensitivity as an indicator of subclinical mastitis detection when SCC increased for early detection of udder skin temperature rising. In this study, a total of 39 udders were diagnosed with subclinical mastitis based on the standard that quarters with SCC>300×103 /mL were suffered from subclinical mastitis. According to the method that udder with skin temperature 1.0℃ higher than the other symmetrical udder could be diagnosed with subclinical mastitis, a total of 22 subclinical mastitis udders could be detected. In all, detectable rate was 58.97% and misdetection rate was 41.03%. What’s more, misdiagnosis rate was zero. The temperature difference method had a detecting rate of 90.48% for dairy cows with only one quarter suffered from mastitis and a detecting rate of 44.44% for dairy cows with both rear left and rear right quarters suffered from mastitis.In conclusion, milk production level had significant effect on udder skin temperature of dairy cows after milking and udder skin temperature after milking increased with the milk production increasment. In order to minimize the influence of milk production on udder skin temperature and detect the udder skin temperature rise caused by inflammation correctly, udder infrared thermography images should be collected 15~30 min before milking to measure udder skin temperature.Season and parity of dairy cows and their interaction had significant effect on udder skin temperature. The effect of season and parity and their interaction on udder skin temperature should be taken into account in order to establish the threshold of udder skin temperature and predict the udder skin temperature.Rear left and rear right quarter skin temperature had no significant difference for healthy dairy cows and they showed symmetrical distribution. Udder skin temperature difference between left and right quarter was not affected by daily rhythm, environment temperature and physiological status of dairy cows. Absolute temperature difference between rear left and rear right quarter skin temperature was less than 1.0℃. Udders with higher skin temperature could be detected and diagnosed with subclinical mastitis by comparison of left and right quarter skin temperature difference.