A study of the factors influencing the reproductive performance of female N’Dama And Fresian X N’Dama cattle in the hot humid forest zone of Ghana.
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Date
1990-10-21
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Abstract
The reproductive records of N’Dama and Fresian X N’Dama cattle at UST Dairy/Beef Cattle Research Station were analysed and the progesterone-radioimmunoassay technique used to investigate the determinants of reproductive performance. Mean birth weights were 17.2 ± 5.1 and 28.32 ± 6.7kg for the N’Dama and Fresian X N’Dama cattle respectively. Bull calves of the Fresian X N’Dama weighed significantly heavier (P < 0.05) than the heifer calves at birth. The mean birth weight of the Fresian X N’Dama calves born in the wet season was also significantly higher (P < 0.05) in the dry season.
Puberty was reached at mean ages of 684.33 ± 133.8 and 626.33 ± 188.96 days for the N’Dama and Fresian X N’Dama heifers respectively. Endocrine function at puberty was, however, abnormal and pubertal heifers had to wait a mean of 69 days before fertile oestrus. Minimum weights of 510 and 180 kg were required for the initiation of sexual cyclicity in the N’Dama and fresian X N’Dama respectively.
The mean ages at first calving were 1045.93 ± 148.9 and 990.0 ± 161.4 days for the N’Dama and Fresian X N’Dama respectively, while the respective calving intervals were 511.6 ± 166.6 and 368.0 ± 162.8 days. Calving intervals was significantly longer (P < 0.05) for the N’Dama which calved in the wet season than for those which calved in the dry season (558.78 ± 187.1 vs 447.76 ± 177.2 days respectively)
Ovarian luteal inactivity lasted a mean of 180.96 ± 135.9 days for the N’Dama and 82.69 ± 54.6 days for the Fresian X N’Dama. The interval from calving to ovarian luteal activity was, however, significantly lower (P < 0.05) in the N’Dama cows which nursed their calves only up to 3 months compared to those which nursed beyond 3 months (85.0 ± 48.8 vs 256.36 ± 135.5 days respectively).
Mortalities were 20 and 19 percent for the N’Dama and Fresian X N’Dama respectively. Ninety two percent of the N’Dama deaths occurred in calves up to 6 months of age while only 42 per cent of the Fresian X N’Dama deaths occurred in animals of comparable age. Undernutrition and enteritis in calves accounted for 55 percent of the deaths in the N’Dama, but the heartwater disease was more important in the Fresian X N’Dama, accounting for 50 per cent of the deaths.
Age at puberty, season of calving, postpartum anoestrus and culling were found to be important determinants of reproductive performance. The results suggested that early weaning (with supplementary feeding of calves and dams) and culling of non performers
could significantly improve reproductive performance of female cattle in the hot humid forest zone of Ghana.
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A thesis submitted to the Board of postgraduate Studies, University of Science and Technology, Kumasi, in partial fulfillment of the requirements for the
M.Sc. (Animal Science) Degree, 1990