Efficacy of ultrasound examination of heifer's mammary glands for predicting their milk yield.

摘要

This study examined the efficacy of the ultrasound method for determining the contents of secretory and adipose tissue in precalving heifers based on ultrasound images. A link was also determined between the percentage of secretory tissue in the udder and the subsequent milk yield of the heifers during the first 100 days of lactation. This study was carried out in 25 Black-and-White (62.5-92.1% Holstein-Friesian), 25 Red-and-White (53.8-87.5% Holstein-Friesian Red) and 25 Simmental (dual-purpose type) heifers from 15 to 7 days before parturition. Measurements were made using an Aloka SSD 500 (Aloka Co. Ltd, Japan) with a 3.5 MHz transducer and 12 cm linear probe. The ultrasound images were binarized, and the degree of brightness was determined on the greyness scale (0-255 luminance range). The lower and upper brightness thresholds were assumed to be 128 and 255, respectively. The image points with brightness of 0-127 was matched to the adipose tissue, and those with brightness of 128-255 to secretory tissue of the analysed udder quarter. Bright area percentage was calculated in the specified section of the image. The results were recorded, and the surface area of the ultrasound image section and grey area was taken into account, as well as the percentage of grey area. These were recorded as output files. A highly significant correlation was found between the percentage of secretory tissue in the udder of precalving heifers and their subsequent milk yield during the first 100 days of lactation. When improved, this method for evaluating udder structure in heifers based on ultrasound images might be useful in experimental work and breeding practice..