The Incidence of Dystocia in Dorset Horn Ewes

Abstract

The incidence of dystocia was recorded in flocks of Dorset Horn ewes lambing in winter, spring or summer and grazed at 8, 12 or 16 ewes per hectare over a ten-year period. The mean incidence of dystocia was 34% of ewes lambing. Significantly more ewes experience a difficult birth at winter (35%) and spring (39%) than summer (26%) lambings. Neither stocking rates nor pre-lambing ewe bodyweight were related to the incidence of dystocia. The incidence of dystocia was significantly greater in 2-year-old ewes than in any other age group. Foetal size was of major importance in the occurrence of dystocia. Approximately 60% of single and twin born lambs that had birth weights greater than 4.5 kg had a difficult birth whereas in lambs weighing less than 3.2 kg only about 10% were affected. Thirty-six per cent of all perinatal mortality was attributable to dystocia. Approximately 27% of single and 73% of twin presentations in assisted births were abnormal, 31% of all lambs assisted had 1 or both legs retained, 4% had posterior (including breech) presentations and the remaining 8% were of varied forms of malpresentation. Significantly more single male than female lambs experienced a difficult birth and the mean birth weights of single, twin and triplet born lambs that had a difficult birth were greater than the birth weights of singles, twins and triplets born normally.

Reproductive performance and genetic parameters for Australian Dorset Sheep

“…Also differing nutritional regimes for spring and autumn joined ewes due to seasonal changes in pasture during pregnancy and lambing could have contributed to variation in birthweight and subsequent levels of dystocia and lamb mortality (Fogarty et al 1992 3). George (1976) reported higher levels of dystocia amongst Dorset Horn ewes lambing in winter and spring than in summer. The patterns of change in reproductive performance with age, where maximum performance occurred between three and six years (Fig.…”

“…4 (Hall et al 1993)l. However, poor lamb survival has been reported in research flocks [63% (Haughey et al 1985) and 70% (Hall et al 1994)], with dystocia being a major cause of loss (Fogarty 1971;George 1976George , 1980. Data on the performance of representative industry flocks are limited.…”

Parturition difficulties in sheep

“…Comparison of the results of the various studies is nevertheless difficult since the outcome of the studies is biased by differences in techniques used and lack of uniformity of definitions and criteria used for assistance, i.e. interference at lambing (Grommers, 1967;Naaktgeboren et al, 1971;Krueger and Wassmuth, 1974;George, 1975George, , 1976Bosc and Cornu, 1976;Woolliams et al, 1983a).…”

Evaluation of Sheep and Goat Dystocia Cases Submitted to Our Clinic: Etiology, Clinical Approach and Results

“…Sunulan çalışmada Kloss ve ark. (2002) hariç diğer araştırıcılar ile paralel (Alaçam, 1974;George, 1975;George 1976;Deen 1995;Kloss ve ark., 2002) olarak maternal sebepler ile daha sık karşılaşılmış ve en çok ringwomb (%21.84), ikizlik (%20.69), presentasyon pozisyon ve duruş bozuklukları (%20.69) ve prolapsus vagina (%14.94) gözlenmiştir. Gözlemlerimiz esnasında küçük ruminant güç doğum probleminde anılan sebeplerin birbirleri ile bağlantılı olması sınıflandırılmada bazı problemlere yol açabileceği şüphesi uyandı.…”

“…Retrospektif bir çalışma sonuçlarına göre (Kaymaz ve ark., 2004), Doğum ve Jinekoloji Kliniği'ne getirilen koyunlarda %45.11, keçilerde ise %25.14'ünün güç doğum problemi ile karşılaşıldığı gözlemlenmiştir. Dystocia, en çok ilk doğumlarda, çoğul gebeliklerde, erkek yavrularda, fötopelvik orantısızlıkta ve bahar aylarındaki doğumlarda rastlanılmaktadır (Çetin ve Kocamüftüoğlu, 2015;George 1975;George 1976).…”