Use of ultrasound scanning to estimate teat wall thickness in Murciano-Granadina goats.

摘要

To evaluate the ultrasound technique as a method for estimating the effect of mechanical milking on teat thickness in Murciano-Granadina goats, the following work was carried out with a twofold objective: (1) to study the most suitable ultrasound exploration frequency for this breed and the effect of the operator in applying the technique and (2) to validate the approach, comparing it with measurements taken by another estimation method (cutimeter) and performing ultrasound examinations in cows using the same methodology. To this end, three studies were designed. In the first study, 2 experiments were carried out: (a) the first (E1) tested the frequencies 5, 7.5 and 10 MHz; (b) the second (E2) tested the frequencies 3.5 and 5 MHz. In the second study, 2 different independent operators (OP) performed sonography on the same animals (E3), chose the best image of ultrasound examinations recorded as a video sequence (E4) and carried out measurements on ultrasound images (E5). In the third study, the technique tested in goats was applied in 10 Holstein cows (E6) and, finally, ultrasound scans were performed at 5 MHz frequency and cutimeter measurements taken in 63 goats (E7). The following variables were measured in the ultrasound scans: teat wall thickness (TWT), teat wall area (TWA) and teat end area (TEWA). The cutimeter was also used to measure teat wall thickness (TT). From the results obtained, we observed that frequencies of 5 and 7.5 MHz were the most suitable to estimate the teat wall changes brought about by mechanical milking. Moreover, applying the same methodology and frequencies in Holstein cows, the results achieved were similar to those published in the bibliography and the variables measured (TWT, TWA and TEWA) presented a high and significant correlation (R=0.62) with the variable (TT) measured by cutimeter. OP experience had an effect on TEWA before milking in all three experiments (E3-E5) and in TWT, TWA and TEWA after milking in E4 and E5. Despite the effects observed for some variables before and after milking, a significant effect was only found for the difference (after-before milking) in TEWA in E3 and TWT in E4. The ultrasound technique used can serve as a useful tool to evaluate teat wall thickness changes caused by mechanical milking in goats. Nevertheless, it would be appropriate to carry out another study to develop IT tools to minimise the operator effect in the measurement of ultrasound variables.