Relationship of Maternal Plasma Progesterone and Estrone Sulfate to Dystocia in Holstein-Friesian Heifers and Cows

抄録

Thirteen primiparous and 41 multiparous Holstein-Friesian cattle were used to study the relationship between maternal plasma progesterone (P₄) and estrone sulfate (E₁S) concentrations and the prevalence of dystocia. The calvings in 4 heifers and 30 cows were normal (eutocia), while the calvings in 9 heifers and 11 cows were difficult (dystocia). Neither the concentrations of P₄ nor E₁S were different between the groups with eutocia and dystocia from days 90 to 270 of pregnancy. However, a few days prior to parturition, eutocial cows and heifers showed a sharp decline of plasma P₄, while dystocial cattle did not show such a remarkable decline of P₄ concentration. Plasma P₄ levels in dystocial cows a few days antepartum were significantly higher than in eutocial animals (P<0.05 or P<0.01). Prepartum E₁S concentrations were significantly lower (P<0.05) in dystocial than eutocial cattle during the prepartum period from days 6 to 1 in heifers and from days 3 to 1 in cows. These results suggest that insufficient production of E₁S and delayed regression of the corpora lutea are possible causes of dystocia in cattle.