Abstract
The reason why shearing ewes in mid-pregnancy 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 glycoprotein-reactive 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 µm2 in NSE) and in the total muscle area of the sample fragment (41,128, 7 µm2 and 31,942.7 µm2 , 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.
Highlights
The sheep farming has high social and economic importance, since it is an agricultural activity that originates various products such as meat, dairy products, wool and leather
The shearing of sheep during gestation has been commonly used as an alternative because it is capable of altering the placental metabolism (Black et al, 1990), the body weight of lambs (Ribeiro et al, 2010)
When analyzing the levels of glycoproteins, we found that they were in a higher concentration in the SE group, suggesting that they may be responsible for the increase in body weight
Summary
The sheep farming has high social and economic importance, since it is an agricultural activity that originates various products such as meat, dairy products, wool and leather. A problem faced by this industry is reproductive losses, represented by high mortality rates of newborns (Dwyer et al, 2006). Adverse climatic conditions and low birth weight are the main causes of death of lambs in the perinatal period (Labeur et al, 2017; Godfrey et al, 2017; Elizalde et al, 2018). The condition tends to worsen, since low body weight may. This work aimed to evaluate whether shearing pregnant ewes would have any effect on fetal liver and muscle glycoprotein deposits (GAD)
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