Echotextural characteristics of the mammary gland during early lactation in two breeds of sheep varying in milk yields

Abstract

The main goal of this preliminary study was to determine and compare ultrasonographic characteristics of the mammary gland in two genotypes of ewes varying in milk productivity at 2, 3 and 4 weeks after lambing. Ultrasonographic images of the udder were obtained using the 5.0-and 7.5-MHz transducers, in axial and coronal planes, in four low milk-yielding Polish Mountain sheep and six high milk-yielding Olkuska ewes. All ultrasonograms were subjected to computerized image analyses using commercially available image analytical software (Image ProPlus  ; Media Cybernetics Inc., San Diego, CA, USA) to determine numerical pixel values (NPVs) and heterogeneity (pixel standard deviation-PSD) of the mammary gland parenchyma. During the 28-day period post-partum, the Olkuska sheep exceeded (P < 0.05) Polish Mountain ewes in milk productivity (31.6 ± 2.7 l and 25.0 ± 4.2 l, respectively; means ± SEMs) as estimated by the mean weight gains of suckling lambs. In animals examined with the 5.0-MHz transducer, mean NPVs of the mammary gland parenchyma in Olkuska ewes and mean PSD in both genotypes of ewes were lower (P < 0.05) before than after milking. In addition, PSD recorded both before and after milking were lower (P < 0.05) in the Polish Mountain compared with Olkuska breed. Mean PSD values for the mammary gland were less (P < 0.05) before than after milking in Polish Mountain ewes and they were greater (P < 0.05) in Olkuska compared with Polish Mountain ewes examined with the 7.5-MHz probe after milking. It can be concluded that milk quantity, histomorphology of the udder and ultrasound transducer frequency may all impinge on the echotextural characteristics of the mammary parenchyma in different breeds of sheep. Our observations warrant future studies of correlations between milk composition, mammary gland histophysiology and ultrasonographic image attributes of the mammary gland in ruminants.

Associations between Mammary Gland Echotexture and Milk Composition in Cows

“…Mammary gland NPVs and PSDs were significantly greater after than before milking, which is in complete agreement with our earlier observations in low-and high-milk yielding sheep [13]. It is evident that the removal of the hypoechoic excretory product during complete milking alters the echotexture of the mammary parenchyma [19].…”

“…One year later, a personal computer-based image analytical software, named USOFT, was developed to determine the percentage of intramuscular fat in live animals [27], but subsequently it has also been shown that USOFT software could accurately interpret the scanning results only in the range of 2-8% of intramuscular fat content [28]. It has recently been suggested that variations in milk yields and chemical composition between different genotypes of sheep may contribute to the differences in echotextural attributes of the mammary gland in lactating ewes [13]. In the present study, echotextural variables of the mammary parenchyma in cows, determined mainly in the sagittal plane, were significantly correlated with protein and lactose during both milking periods, with freezing point depression in the morning and casein and solids non-fat in the evening.…”

“…In each ultrasonogram, a polygonal area of interest within the mammary gland parenchyma was selected avoiding reflection artifacts, visible blood vessels, lactiferous ducts, connective tissue and gland cisterns ( Figure 1). Following area selection, the mean numerical pixel values (NPV) and pixel heterogeneity (pixel standard deviation-PSD) of each polygonal area were computed [13].…”

Correlations Among Ultrasonographic, Physicochemical and Sensory Characteristics of Pectoralis Major Muscles in Turkeys Reared in a Sustainable Farming System

“…The only chemical constituent that was signi cantly correlated with echotextural variables was moisture. The latter contrasts with earlier ultrasonographic studies of the pectoral muscles in broiler chickens [21] and different mammalian organs/tissues [47,48] where signi cant correlations were consistently seen between rst order echotextural variables and fat/protein content. Although the fact that turkey meat is less fatty than that of other livestock species may explain a lack of correlations with crude fat content, a reason for a lack of signi cant correlations with crude protein content remains unknown.…”

Effects of Increased Growth Rates Prior to the First Breeding as Ewe Lambs and Pregnancy Rank on Mammary Glands of Two-Year-Old Ewes

“…The present results suggest that there were no carry-over effects of increased growth rates between weaning and breeding at seven months of age on the morphology and dimensions of the internal structures of the mammary gland of two-year-old ewes. Ultrasound imaging, however, enables only the udder dimensions to be visualised [15,22] and echo-textural characteristics [28,29] of the mammary internal structures to be assessed. Further investigations may be warranted to determine the effect of increasing growth rates prior to the first breeding on the cellular development and function of the ewe mammary gland, particularly if greater live weight differences than seen in the present experiment can be achieved.…”