Estimates of phenotypic and genetic trends of growth traits in N'dama herd in Nigeria
Data on birth weight (BTHWT), 205-day adjusted weaning weight (ADWNWT), and pre-weaning daily gain (ADG) of N'Dama reared at Fasola Stock Farm between 1947 and 1984 were obtained and used to estimate phenotype and genetic trends of these traits. Estimated phenotypic trend was 0.07±0.02kg/yr, 0.18±0.06kg/yr and -0.005 ±0.003kglyr for BTHWT, ADWNWT and ADG respectively. In contrast, all estimated genetic trends were relatively small and not significantly different from zero. They were 0.02±0.05kg/yr, 0.02±0.05kg/yr and 0.1g/yr for BTHWT, ADWNWT and ADG respectively. The sequential polynomial fitting of the data set indicated that quadratic function adequately described the data with the following regression equation:
Y = 9.91 + 0.01b1 + 0.02b2
Y = 46.44 - 0.15b1 + 0.01b2
Y = 0.21 - 0.0002b1 + 1.18b1 for
BTHWT, ADWNWT and ADG respectively for phenotypic trend curve while for genetic trend curve Y = 0.10 – 0.01b1 - 0.34b1 was obtained for BTHWT and ADWNWT and Y = 0.002 - 0.0002b1 - 70.85b2 for ADG.
Keywords: N'dama cattle, growth, phenotype, genotype, estimate