Association of twin pregnancy diagnosis and parturition with days open, days pregnant at diagnosis, parity, and milk production in dairy cattle

Abstract

Association between twin pregnancies diagnosed by either rectal palpation or observation at calving and days open, days in gestation at pregnancy diagnosis, parity, and milk production in the lactation preceding the birth of twins were studied on 5493 cows on 14 California dairies. A total of 196 bicornual (3.57%) and 74 unicornual (1.35%) twin pregnancies were diagnosed, but the actual twinning rate at parturition was 6.86%. The incidence of twins at diagnosis and at calving was dependent on parity and independent of days open. Detection of twins at diagnosis by rectal palpation was dependent on days pregnant at diagnosis. Cows in parities greater than 2 diagnosed with twin pregnancies and calving with twins had higher peak mild production than cows diagnosed with single pregnancies and calving with singles, respectively. However, when data were stratified by dairy, no significant difference occurred in peak milk production between cows diagnosed with singles or twins, and no significant difference occurred between cows calving with singles and twins. The 305 day mature equivalent milk production (ME) did not differ between cows diagnosed or calving with twins and singles. Optimal time for diagnosis of twins was at 51 to 60 day postbreeding.