Hormonal Manipulation of Some Infertility Problems in Cross-Bred Cows in the Sudan

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Salih Nasir Mussa Nasir, Nasir
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This study was carried out using 38 crossbred heifers, 41 crossbred (Butana x Friesian) dairy cows, 36 repeat breeder cross-bred dairy cows at Khartoum University Farm. The heifers were fed ad libitum on green forage only. The post-partal dairy cows were fed on green forage supplemented with concentrates. The body weights were taken once monthly and three samples of blood were collected at intervals of 10 days to determine the progesterone concentration. The age at puberty was determined in the cross- bred heifers by occurrence of first oestrus and ovarian activity detected by plasma progesterone level determination. Ovarian cycle commenced in 21 heifers (55.5%) of the heifers at the age of 26-31 months with a body weight of 161±11 kg. From the age of 32 months onwards, all heifers reached puberty scoring an average body weight of 208.3±40.8kg. The study showed a highly significant correlation (r=0.91) between body weight and average progesterone concentration in prepubertal heifers. The postpartum cows were either treated with GnRH at 14 days post parturition or kept as control. They were monitored throughout the study for body weight changes, days to first progesterone rise, first observable heat and pregnancy rate. The study showed significant differences between body weight changes, time elapsed to first progesterone rise and body weight at first observable heat in GnRH treated and in the control cows. However, body weight at delivery, body weight at first progesterone rise and period of first oestrus was not significantly different in GnRH treated and control cross-bred cows. Body weight change percentage had significant effects on post-partal fertility in treated and non-treated cross-bred heifers. The period of first postpartum oestrus was shorter in GnRH treated cows than the control. There was a significant difference between pregnancy rate in control and GnRH treated postpartum cross-bred cows. The experiment on repeat breeder cows was designed to explore effectiveness of different hormonal treatment on conception rates using artificial insemination at a fixed time. In repeat breeder cows the mean progesterone concentration levels on the day of the first PGF2α injection were 3.48±0.89 and 2.22±0.54 ng/ml in the cows which conceived and those which failed, respectively. The results revealed that the luteolysis was complete within 72 hours of PGF2α injection as confirmed by plasma progesterone level. Partial or incomplete autolysis was also observed in two non-pregnant cows. The study showed that the mean progesterone concentrations were 2.60±0.32 and 5.56±0.25 ng/ml in the pregnant cows at 6 and 21 days post insemination, respectively. There were significant differences (P < 0.01) in progesterone concentrations at the second injection of the hormone in 6 and 21 days post insemination between pregnant and non-pregnant cows. The progesterone concentrations in the different stages of the treatment were higher in conceived than not conceived cows. It is concluded that the best results of conception rates were obtained with PGF2α plus PMSG followed by PGF2α with uterine wash. SURGERY
Hormonal Manipulation of Some Infertility Problems in Cross-Bred Cows in the Sudan