Mid-pregnancy ewe shearing and the effects on fetus liver and muscle glycoprotein deposits

Abstract

The reason why shearing ewes in midpregnancy does increase the lamb birth weight is not completely clears. Therefore, we focused on the analyses of the deposition of glycogen in different fetal tissues to investigate this issue. Thirteen pregnant Australian Merino ewes, raised in native pasture, were separated in two groups. One group (n = 7) was shorn (SE) at 70 days of pregnancy, whereas another group (n = 6) remained unshorn (NSE). Cesarean section was conducted in all the ewes at near parturition, when placenta and fetuses sampling were collected. Placenta, liver and muscle samples were fixed and stained with glycoproteinreactive acid-Schiff acid for analysis under light microscopy. The quantification of these glycoproteins was performed with the support of a program that analyzes the measurement of the intensity of staining by field. Five random fields from each sample were used, where statistical analyzes was used as normal test T. Among the analyzed regions, the deposition of glycoprotein between SE and NSE groups was statistically different in the hepatic portal vein (54,499.23 µm 2 in SE and 34,830.73 µm 2 in NSE) and in the total muscle area of the sample fragment (41,128, 7 µm 2 and 31,942.7 µm 2 , respectively; P < 0.05). We conclude that shearing ewes at the 70th day of gestation lead to accumulation of glycoproteins in the liver and muscle of fetuses, which may be responsible for the increase in birth weights in that group.

Assessment of dopperfluxometric indices of maternal-fetal structures in pregnant ewes

“…The adequate blood supply is key to a healthy pregnancy, therefore, the monitoring and determination of vascular indices proposed in our study are of paramount importance. Although there are already previous data on vascular parameters of ewes during pregnancy, more specific data related to the presence of wool can provide more accurate information since it has been described by Junior et al (2019) that the mean weights of the fetuses were higher (3.688 kg) in shorn ewes when compared to unshorn ewes (3.596 kg) and that the average placental weights also differed between the groups (2.287 kg and 1.923 kg, respectively); showing that the wool factor has an influence on placental development and, consequently, on vascularization and adequate nutrition of the fetuses. Silva et al (2018) conclude that their data show that preterm neonates are less adapted to the odds of labor and to overcome the immediate changes of extra-uterine life.…”