Development and validation of a new method for visual detection of estrus in mithun (Bos frontalis)

The objectives of this study were (1) to develop a suitable scoring scale for estrus detection based on frequency and reliability of behavioral signs of estrus in mithun (Bos frontalis) and (2) to validate the accuracy of this method for detection of estrus in primi- and multiparous mithun cows. The study consisted of two experiments. In experiment I, all animals were observed for 30 min at 2 h intervals for at least 35 days, for signs of estrus. Estrus was further confirmed by rectal examination of the reproductive organs and quantification of plasma progesterone concentrations. Based on the frequency and reliability of a particular sign, a cumulative point scale composed of seven estrous signs that were scored with points, ranging from 3 to 100, was developed. When the sum of the scores exceeded 100 points, the animal was considered to be in estrus. This was again confirmed by rectal examination of the genitalia and quantification of plasma progesterone concentrations. Calculation of efficiency and accuracy of the developed scale showed that this scale was 100% efficient and accurate, irrespective of parity. In experiment II, the scoring scale was tested for its efficiency and accuracy for detection of estrus in primi- and multiparous mithun cows based on the behavioral observations recorded twice a day at 0630 and 1630 h for at least 35 days with each observation period lasting for 30 min. Interestingly, efficiency and accuracy of the scale for detection of estrus was 100% in this experiment. Behavioral estrus was more intense in primi- than multiparous mithun cows in both experiments. Duration of estrus was longer in primi- than multiparous animals. The results of the present investigation revealed that no individual behavioral sign of estrus can be used alone for estrus detection in mithuns; whereas the efficiency and accuracy of the scoring scale composed of seven estrous signs were 100%, even when animals were observed twice each day. In conclusion, the scoring scale that has been developed was suitable for detection of estrus in mithuns with high efficiency and accuracy. However, the scale should be validated for use by farmers to assess its practical usefulness.