Reproductive and milking performance of a herd of Friesian W N'Dama cattle
AbstractProduction records of a herd of Friesian W N'Dama cattle reared on-station were examined to assess their potential for use as dairy animals in the tropics. In addition, the radio- immunoassay technique was used to measure plasma progesterone concentrations to determine the attainment of puberty and resumption of ovarian activity postpartum in heifers and cows, respectively. A Friesian bull was always used to serve females on heat. Bull calves were significantly (P< 0.05) heavier at birth than heifer calves; the respective mean (1SE) weights being 3011 kg and 2711kg. The season of birth also significantly affected birth weight with calves born in the wet season being heavier than their dry season born counterparts (wet = 3111 kg; dry = 2611 kg; P<0.05). Puberty was attained at a mean age of 704144 days when the heifers weighed on the average 18117 kg. Heifers calved for the first time at 990 144 days of age and at a mean weight of 2501 6 kg. Ovarian inactivity postpartum lasted a mean period of 83115 days and the mean calving interval was 371120 days. There was a significant (P<0.01) genotype effect on lactation milk yield and length of lactation. First generation (F1) cows had relatively poor milking performance, producing a mean of 7941260 kg of milk in 159133 days of lactation as compared to second generation (F2) cows which produced 17671137 kg of milk in 298118 days. Cows which calved in the wet season lactated significantly (P<0.05) longer than those which calved in the dry season (260126 days and 193120 days, respectively). The effect of the interaction between season and partity on lactation milk yield was also significant (P<0.05) with first parity cows which calved in the dry season producing less milk than the others.
(Ghana Journal of Agricultural Science, 1996, 29(2): 115-124)
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