Abstract
The purpose of this study was to investigate the proportion of twins carried to term and the sex ratio of twin calves at birth in Holstein-Friesian dairy cattle kept on commercial farms in Devon and Cornwall, England. Ten farms were used in the study. Fifty four cows with twin pregnancies were identified using trans-rectal ultra-sonographic examination between 30 and 70 days of gestation. The farm records were subsequently used to derive the number of calves born. Farm records of 66 additional sets of twin births with the sex of the calves recorded were also identified. Of the 54 cows diagnosed with twin pregnancies, 16 cows (29.6%) aborted or absorbed both fetuses, 11 cows (20.4%) carried one calf to term and 27 cows (50%) carried both calves to term. In the calf sex analysis of the additional 66 sets of twins: 13♂♂ calves (19.7%), 18 ♀♀ calves (27.3%) and 35 ♂♀ calves (53.0%). There was no statistically significant difference from an expected ratio of 1♂♂:2♂♀:1♀♀ (p = 0.61). This study provides bench marks for the expected abortion/absorption rates following the early ultra-sonographic diagnosis of twin pregnancies in comparable populations and supports earlier observations that the expected sex ratio for twinning approximates to1♂♂:2♂♀:1♀♀.
Highlights
Twinning in dairy cattle is associated with higher milk yields [1], an increased incidence of abortion [1], dystocia [1], retained fetal membranes [1], metritis [1], Freemartinism [1, 2] and an extended calving to conception interval [1,3]
The incidence of twinning reported in dairy herds varies between studies, herds and parities but is an average of 4% has been reported in UK herds [5]
The purpose of this study was to investigate the proportion of twins carried to term and the calf sex ratio of twin calves in Holstein-Friesian dairy cattle kept on 10 commercial farms in Devon and
Summary
Twinning in dairy cattle is associated with higher milk yields [1], an increased incidence of abortion [1], dystocia [1], retained fetal membranes [1], metritis [1], Freemartinism [1, 2] and an extended calving to conception interval [1,3]. Large scale studies of the twin calf sex ratios have been reported [8,9,10]. The purpose of this study was to investigate the proportion of twins carried to term and the calf sex ratio of twin calves in Holstein-Friesian dairy cattle kept on 10 commercial farms in Devon and Cornwall, England
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