Crossbreeding, Additive and Heterotic Effects on Production Traits in Jersey Crossbred Cattle at Agricultural Research Station , Legon
Date
2004-07
Authors
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Journal ISSN
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Publisher
University of Ghana
Abstract
Relative performance of breed groups, additive and
heterotic effects on milk production, reproduction and calf
growth traits in Jersey x West African Shorthorn (WAS) and
Jersey x Sokoto Gudali (GUD) crossbred cattle were studied
using sixteen years field records kept at the Agricultural
Research Station, Legon.
The genotypes consisted of WAS; 1/2 Jersey, 1/2 WAS
(WAS Fj); 3/4 Jersey, 1/4 WAS (WAS Be); GUD; 1/2 Jersey,
1/2 GUD (GUD Fj) ; 3/4 Jersey, 1/4 GUD (GUD Be).
Milk production traits analysed were first lactation
milk yield, average lactation milk yield, average daily milk
yield, annualized milk yield, lactation fat yield, fat
percentage and lactation length. Analysis of reproduction
traits included age at first calving, number of services per
conception and calving interval. The calf growth traits
examined were birthweight average daily gain to weaning and
weaning weight.
All traits were analysed by least sguares fixed model
procedures using the GLM methods in SAS (1987) to generate
genotypic least sguares means. Additive and heterotic
effects on crossbreds were estimated using the additivedominance
model.
With regard to the milk production traits and calf
growth traits, the performance of GUD was significantly
(P < .01) better than WAS. WAS and GUD were similar for the
reproductive traits except for calving interval where GUD
had a significantly (P < .01) shorter calving interval than WAS (475 days as against 551 days). WAS Fj and GUD Fj
crossbreds were significantly (P < .05) better than their
corresponding purebreds for all the traits examined except
for birth weight where both Fj's were similar to their
respective purebreeds. This indicated that crossbreeding
with Jersey would lead to significant increases in the
production level of the local breeds. GUD Be and GUD Fj cows
were similar for the milk production traits whereas WAS Be
cows were superior to WAS F1 cows. WAS Be calved
significantly (P < .05) earlier for the first time
(36 months) than WAS Fj (42.3 months). There was no
difference between WAS Be and GUD Be when compared to their
corresponding Fj' s for the other reproductive traits. WAS Be
and GUD Be calves weighed significantly (P < .01) more at
birth (21.7kg and 24.6kg respectively) than their respective
Fj's (20.1 kg and 23.1 kg respectively).
The performance of WAS Be and WAS FI were similar for preweaning
average daily gain (ADG) and weaning wight. GUD Be
declined significantly (P < .05) in growth rate when
compared to GUD Fj.
Additive genetic breed effects and heterosis contributed
significantly to the improvement in milk production traits
and calf growth traits in the WAS crossbred group. Additive
effects however,- made greater contribution to the
improvement than heterotic effects. Of the reproductive
traits in WAS crossbred group, only the additive effect for age at first calving (-10.2 ± 2.5 months) and the heterotic
effect for calving interval (-102 ± 31.8 days) were
significant (P < .05) and desirable. These results showed
that additive and heterotic effects could be exploited in
crossbreeding to improve growth and milk production in WAS.
Only average lactation milk yield and lactation length
were significantly (P< .05) improved by additive effect
among the milk production traits in the GUD crossbred group.
Additive and heterotic effects were not significant for any
of the reproductive traits in GUD crossbreds. Additive and
heterotic effects however, significantly (P < .05)
influenced calf growth traits in GUD crossbreds.
Description
Thesis(M.Phil)-University of Ghana,2004.