EFFECT OF SHEARING DURING PREGNANCY ON PRODUCTIVE PERFORMANCE IN THE POST-PARTUM PERIOD OF EWES ON EXTENSIVE HUSBANDRY

The use of shearing during pregnancy has been described as a tool for improving productivity in sheep and for minimizing perinatal mortality in lambs through the increase of fetal development. This study assessed the effect of shearing around 74 days of gestation on the productive performance of ewes and lambs during the first month of life. Forty Corriedale ewes were inseminated in autumn in Southern Brazil. All ewes were kept together at the same pasture under extensive husbandry conditions. The ewes were randomly separated into two treatment groups: twenty animals were completely sheared at 74 ± 6 days of pregnancy, and twenty were kept without sheared during pregnancy, composing the control group. Ewes and their lambs were evaluated at three different times during the experiment: at birth, between 15 and 21 days post-partum and between 22 and 45 days post-partum. Ewes had their body condition score, body weight, placental weight, milk production and serum concentrations of beta-hydroxybutyrate measured, while lambs had hematocrit, hemoglobin, and plasma lactate and glucose, as well as body weight at birth and until wean determined. Values of hematocrit and hemoglobin were lower and body weight at birth and at wean was higher in the group of lambs born from sheared ewes. Placenta weight was higher in sheared ewes. Body condition score and beta-hydroxybutyrate showed no differences between groups. Milk production of sheared ewes (1.26 L/day) was higher than in control group (0.93 L/day). Shearing ewes at 74 days of pregnancy was efficient for the better development of lambs at post-birth, reducing perinatal mortality rates.

妊娠期间剪毛（shearing）已被证实可作为提升绵羊生产性能、通过促进胎儿发育降低羔羊围产期死亡率（perinatal mortality）的手段。本研究评估了妊娠约74天时剪毛对母羊生产性能以及羔羊出生后首月生长表现的影响。40只考力代（Corriedale）母羊于巴西南部秋季接受人工授精，所有母羊均在相同牧场以粗放饲养（extensive husbandry）方式混群饲养。将母羊随机分为两个处理组：20只于妊娠74±6天时进行全身剪毛，另外20只妊娠期间不进行剪毛，作为对照组。实验期间分别于三个时间点对母羊及其羔羊进行检测：分娩时、产后15~21天以及产后22~45天。对母羊测定的指标包括体况评分（body condition score）、体重、胎盘重量、产奶量以及血清β-羟丁酸（beta-hydroxybutyrate）浓度；对羔羊测定的指标则包括红细胞压积（hematocrit）、血红蛋白（hemoglobin）、血浆乳酸（plasma lactate）与葡萄糖（glucose）含量，以及出生至断奶期间的体重变化。剪毛组母羊所产羔羊的红细胞压积与血红蛋白水平更低，而出生时及断奶时的体重更高。剪毛组母羊的胎盘重量更高。两组母羊的体况评分与血清β-羟丁酸水平无显著差异。剪毛组母羊的产奶量（1.26升/天）高于对照组（0.93升/天）。于妊娠74天时对母羊进行剪毛，可有效促进羔羊出生后的生长发育，降低围产期死亡率。