University of Khartoum

Studies on the Relationship Between Conception Rate and Time of Service, in Holstein Friesian Dairy Cows in the Sudan

Studies on the Relationship Between Conception Rate and Time of Service, in Holstein Friesian Dairy Cows in the Sudan

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Title: Studies on the Relationship Between Conception Rate and Time of Service, in Holstein Friesian Dairy Cows in the Sudan
Author: Lino Libo Ador, Kur
Abstract: The study was conducted to determine the relationship between conception rate and The time of service relative to the onset of oestrus and ovulation time in Holstein- Friesian cows during Winter (Nov. to Feb.), hot dry Summer (Mar. to June), and hot wet Summer (July to Oct.). 146 cows from the control group, and 92 cows from the lutalyse treated group were used in this study. Out of these numbers 24 cows from each group were allocated to monitor the time of ovulation. 53% of the onsets of oestrus in both the control and treated cows were associated with night hours, 18.00 to 06.00 hours, and onset of oestrus occurred most frequently between 18.00 and 20.00 hour in both control and treated cows. Other behavioural signs of oestrus were associated with daylight hours, and the peak of mounting activity was from 16.00 to 18.00 hours in the control group of cows, and from 18.00 to 20.00 hours in the treated group. The factors influencing the onset of oestrus and other behavioural signs showed that 43, 56 and 63% of the oestrus onsets occurred at night during winter, hot dry summer, and hot wet summer, respectively. 46 and 62% of the cows at parities 1 or 2, and 3 or over, respectively showed onset of oestrus at night. Onset of oestrus occurred mostly at night in cows at 41-60, 61 -80 and 101 and over days postpartum as compared to cows at 81 - 100 days postpartum. Onset of mounting activity occurred mostly during daylight hours in winter and hot dry summer as compared to the hot wet summer. Onset of mucus discharge occurred mostly at night in winter as compared to the summer seasons. Onsets of mounting activity and mucus discharge were low at night for cows of all parities. Cows at 41 - 60 days postpartum had the highest mounting activity at night as compared to cows at 61 - 80, 81 – 100 and 101 and over days postpartum, and onset of mucus discharge was low at night for all cows at 41 and over days postpartum. Efficiency of oestrus detection using visual observation was 90%. The mean interval from the onset of oestrus to the time of ovulation was 28.18±0.53 hours in the control group of cows, 27.57±0.41 hours in the treated cows, and 27.88±0.34 hours overall. Treatment, season and parity had no significant effect on the time of ovulation: The optimum time of insemination to achieve the highest conception rate was 13 to 18 hours after the onset of oestrus or 10 to 15 hours before ovulation in the control group of cows, and 7 to 12 hours after the onset of oestrus or 16 to 21 hours before ovulation in the treated cows. The control group of cows had higher conception rates than the treated cows, and seasonal influences on the timing of insemination showed that winter had the highest conception rate followed by the hot dry summer, and the hot wet summer had the lowest conception rate. Insemination of cows at 121 and over days postpartum yielded the highest conception rate followed by inseminations at 61 to 80 days postpartum, and inseminations at 41 to 60 days postpartum yielded the lowest conception rate. Conception rate in cows at parities 1 and 2 was higher than cows at parities 3 and over.
URI: http://khartoumspace.uofk.edu/handle/123456789/14404
Date: 2015-06-23


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