Analysis of Factors Influencing Reproductive Performance of the Dairy Cow by Progesterone Assay in Milk-Fat

Abstract

Factors which influence reproductive performance of the dairy cow were analysed by application of the milk-fat progesterone assay on experimental and private farms, and under field conditions. Management (oestrus observation and timing of AI) had a considerable influence on reproductive efficiency (5·2% insemination during the luteal phase on experimental farms, 21·3% in problem herds under field conditions). On experimental farms with trained herdsman, 4·1% of AI were timed too early during oestrus. Reproductive performance was also affected by follicular cysts (15·8% of cows) and corpus luteum cyst (± endometritis) (10%). Duration of acyclia was longer in the spring compared to other seasons. Acyclia was longer in cows housed in stanchion barns (29 days) compared to loose housing (17 days). The most frequent problem was silent heat (59% of post-partum periods, ratio of silent to observed heat in 32% of post-partum cycles was 1:2·1). Embryonic death accounted for 16·9% of the unsuccessful inseminations. A part of this may be explained by the possibility that the conceptus was not able to exert sufficient luteotropic (or antiluteolytic) stimuli. This is concluded from the occurrence of the cycling pattern of progesterone concentrations in early pregnancy.