Luteal phase deficiency as a possible cause of repeat breeding in dairy cows

Abstract

The incidence of luteal phase dysfunction as indicated by milk progesterone profiles after artificial insemination (AI) and ovulation was investigated in 21 repeat-breeding dairy cows. Eight (38%) cows had a normal progesterone profile; progesterone levels in skim milk rose to 1·0 ng/ml or higher within five days after insemination (0 dayday of AI) and, thereafter, steadily increased to 2·0 ng/ml or higher at mid-luteal phase. Another 13 (62%) cows had an abnormal pattern of milk progesterone levels which indicated luteal phase defects after AI; seven (54%) of the 13 cows showed a delayed rise of the progesterone level until 6–11 days after AI, two (15%) had a comparatively low level of milk progesterone below 2·0 ng/ml through most of the luteal phase, and four (31%) had a combined pattern of a delayed rise and a low level of milk progesterone during luteal phase. After the AI, five (63%) of the eight cows with a normal progesterone profile conceived, while none of the 13 cows which had insufficient luteal function conceived. It is suggested that delayed formation of the corpus luteum, either combined or not combined with lowered secretion of progesterone during luteal phase is one of the causes of repeat breeding in dairy cows.