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|Title: ||Genetic analysis of the performance traits of cattle in the tropics: case study of the K.N.U.S.T. dairy/beef cattle research station in Kumasi|
|Authors: ||Agbemawle, Emmanuel Yao Voemewor|
|Issue Date: ||15-Feb-1999|
|Series/Report no.: ||2741;|
|Abstract: ||A study was made of the performance of 250 Holstein-Friesian cattle comprising 27 imported foundation stocks and their locally-born offspring and 202 Holstein-Friesian x N’dama crossbreds of various grades reared between 1976 and 1996 at the U.S.T. Dairy/Beef Cattle Research Station at Boadi in Kumasi, These animals were mainly managed under field conditions. Genetic and phenotypic parameters were estimated where possible. Levels of inbreeding and their influence on mortality of the Holstein-Friesians born on the farm were also determined.
The average performance of the Holstein-Friesians was below what had been reported from temperate environments. The imported Holstein-Friesians performed significantly better than any other group of cattle used in this study (P< 0.05). The performance of the crossbreds increased with the increase in the proportion of Holstein-Friesian genes they possessed up to the 75% grade in most traits. The animals were disposed of for various reasons. The major reason was death from various causes. Inbreeding did not appear to be an important cause of the high mortality of the Holstein-Friesians at the station since a large proportion (61.17%) of those that died were not inbred.
The repeatability estimates for the imported and locally-born Holstein-Friesians respectively were: - milk yield 0.08 ± 0.095 and 0.41 ± 0.109; lactation length 0.09 ± 0.096 and 0.25 ± 0.116 and calving interval 0.07 ± 0.122 and 0.17 ± 0.144. The heritability values were:- first lactation milk yield, 0.58 ± 0.321 first calving interval 0.19 ± 0.082; Total milk yield 0.31 ± 0.272, Total number of days in lactation, 0.56± 0.408, number of calvings, 0.41 ± 0.333; and first lactation length of at least 100 days duration, 0.15 ± 0.192.
Correlations between the various traits were determined. First lactation milk yield was highly and positively genetically correlated with the second lactation milk yield (rg 0. 65 ± 0.263) and with persistency of milk yield during the early part of the first lactation (rg = 0.90 ± 0.097).
The genetic correlations with total milk yield and with first lactation length were moderate being 0.49 ± 0.372 and 0.57 ± 0.354 respectively.|
|Description: ||A thesis submitted to the Board of Postgraduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirement for the award of the Degree of Master of Science in Animal Breeding, 1999|
|Appears in Collections:||College of Agric and Natural Resources|
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