ELECTRICAL RESISTANCE OF VAGINAL MUCOUS AND IT’S RELATIONSHIP WITH HEAT DETECTION AND PREGNANCY RATE IN COWS

Abstract

The use of Vaginal Electrical Resistance (VER) for oestrus and oestrus cycle and it’s relationship with heat detection and pregnancy rate were evaluated by using three experiments in 47 crossbred cows of Birol upazila at Dinajpur district in Bangladesh. The experimental animals were divided into three groups. VER was measured from all animal in each group. In group 1(n=7), VER was measured throughout the natural oestrus cycle in each every alternative day. Again VER reading were recorded from group II (n= 20) only during oestrus period following natural oestrus and in group III (n=20), the animals were induced oestrus by GnRH+PGF2α to monitoring VER following behavioral oestrus only. The relationship with the VER during of oestrus and conception rate were considered. Results of the VER were represented by average (mean±SD) VER among different days of the estrus cycle. The highest value was 354.8±65.0Ω at day10 and lowest was 201.0±13.4Ω at day0 in natural estrus. The average (mean±SD) VER were 247.1±14.4Ω, 204.1±20.2Ω, 254.8±20.3Ω and 322.7±37.0Ω at proestrus, estrus, metestrus and diestrus. Finding of highest VER to lowest VER during the four phase of oestrus cycle were (235-270)Ω during proestrus, (175-241.7)Ω during oestrus, (231.7-293.3)Ω during metoestrus and (243.9-352.2)Ω during dioestrus. The maximum average value of VER during oestrus period was208.3±16.7Ω and 215.3±32.8Ω in group II and group III animals, respectively. The VER was significantly (P<0.05) higher (215.3±32.8Ω) than the group II (208.3±16.7Ω). The average (mean±SD) VER at pregnant and non-pregnant cows were 209.3±26.1Ω and 233.9±37.4Ω, respectively. out of 47 cows 36 cows were pregnant. The percentage of pregnancy was 76.6. The range of VER of the pregnant cows was (166.7-263.3)Ω during oestrus period and the cows failed to conceive which had 173.3Ω to 283.3Ω to 23.4%. The non-pregnant (233.9±37.4Ω) cows showed VER significantly higher (P<0.05) than the pregnant cows (209.3±26.1Ω). Highest percentage (90.5%) of pregnancy rate was found When Vaginal Electrical Resistance was ranged between 190-220Ω during the period of insemination. Here lowest percentage (44.4%) was observed when VER was ranged between 250-290Ω during insemination. The study suggested that VER can be used successfully to predict the stages of the oestrus cycle, to comparison VER during oestrus between natural oestrus cows with cows induced oestrus by GnRH+PGF2α and also be used for determining pregnancy rate.