lnvestigations on repeat breeding crossbred cattle with history of prolonged estrus

Abstract

Repeat breeding cattle (22-11 heifers and 11 cows in second to fourth parity) with the history of prolonged estrus (group 1) were examined percentally at 3-5 day intervals for single or 2 consecutive estrous cycles and blood samples were taken on each day of observation to estimate psogesterone profiles. Similar observations were also taken on 6 healthy, regularly cycling animals (4 cows. 7 heifers) selected as control (group 2). The approximate day of ovulation was decided on the basis of day of onset and end of estrus and presence of CL on per-rectal palpation along with the blood plasma progesterone values on day 6 after the end of estrus. A low body condition score (ranging from 2.0-2.5) of the animals showing prolonged estrus than the control animals (3.0-4.0) was observed. Mean estrus period of the repeat breeder animals (3.77±0.87 days) was significantly higher (P&lt0.05) than the control group (1.O-1.5 day). All the animals (n=22) having prolonged estrus period showed delayed ovulation and out of them, 10 showed mean blood progesterone levels of 0.153±0.087ng/ml during estrus period compared to those of control group (1.52±0.047 ng/ml),w hile 12, cattle showed higher (P&ltO.05) (0.806±0.623 ng/ml) the suprabasal progesterone levels. The suprabasal progesterone levels during estrus might have casued delayed LH peak and be an important factor in the causation of repeat breeding syndrome.