Infrared thermography as a tool to determine teat tissue changes caused by machine milking in Murciano-Granadina goats

Given the scant information found in the review of the literature on the use of infrared thermography as a method to estimate the variation in teat tissue thickness caused by machine milking in goats, this work was proposed with a threefold objective: (1) to fine tune the temperature measuring technique for thermographic images; (2) study the effects of mammary gland health status in application of the technique; and (3) study the relationship between thermography and ultrasound scanning as methods for estimating the effect of machine milking on teat wall thickness. Thermographic images were taken in both glands, along with ultrasound scans of both teats, in 30 Murciano-Granadina goats from different parturition numbers, before and after milking, classifying the animals according to mammary gland health status (FREE: Somatic cell count (RCS) <1,000,000 cells/mL and negative bacteriology; INF: infected, positive bacteriology; UNS: unspecific mastitis, RCS > 1,000,000 cells/mL and negative bacteriology). In the graphic images, we determined the temperature (7) at specific points (P) and areas (A) of the teat (at the tip; TPP; at 1 cm: TP1 and AP1; at 2 cm: TP2 and AP2; at 3 cm: TP3 and AP3 from the teat end) and in the udder (TPU and TAU). The teat wall thickness (TWT), teat wall area (TWA) and teat-end wall area (TEWA) in the ultrasound images of the teat were also determined. Mechanical milking caused a significant increase (P < 0.05) of the mean temperature by 6.6, 4.9, 2.5 and 1.5 degrees C at the tip, 1, 2, and 3 cm from the teat end. No differences were found between the point and area methods in estimating temperature changes in the teat caused by machine milking, and the measurements taken at 3 cm from the teat end are considered the most suitable for this calculation, as they were not affected by the mammary gland health status: UNS glands presented a lower temperature at 1 and 2 cm from the teat end before milking and the greater temperature difference after milking compared to the pre-milking values. Similarly, although mechanical milking caused an increase in temperature and teat wall thickness, a significant correlation, in this case negative, was only found between both variables at the teat end and at 1 and 2 cm from the tip in the UNS glands before and after milking. Depending on the results found, thermography can detect teat temperature increases caused by machine milking. Nevertheless, further works are necessary to study which infectious and non-infectious factors related with the animal or the milking machine, among other aspects, could affect application of the thermography technique in goat livestock. These studies would also allow us to determine the temperature increase threshold after milking after which damage to teat integrity might occur. (C) 2013 Elsevier B.V. All rights reserved.