1. T.L. Tyasi1,2, D. Norris2, J.W. Ng’ambi2, A. Maiwashe,1 K.A. Nephawe3
Crossbreeding effects for body weight in a diallel cross of three chicken genotypes
T.L. Tyasi1,2, D. Norris2, J.W. Ng’ambi2, A. Maiwashe,1 K.A. Nephawe3
1ARC-Animal Production Institute, Private Bag X2, Irene, 0062, South Africa
2Department of Animal Science, University of Limpopo, Private Bag X1106, Sovenga, 0727, South Africa
3Department of animal Science, Tshwane University of Technology Private Bag X680, Pretoria, 0001, South Africa
Heterosis: H% = AB- (0.5AA+0.5BB)/ (0.5AA+0.5BB)* 100 (Fairfull, 1990)
SCA = {(AB) + (BA)}/2 – {GCA (A) +GCA (B)}/2
AA is represent the first purebred
BB represents the second breed
AB is a cross between breed A and B
BA is its reciprocal.
GCA= X-u
X is the parent mean and u is the overall mean
INTRODUCTION
Figure1: Heterosis percentage for body weight at different ages.
Table 1: General combining ability (GCA) for body weight of chickens at different ages. .
Table 2: Specific combining ability (SCA) for body weight of chickens at different ages.
Based on cross, heterotic effects for body weights in Figure1 were mostly positive and ranged from to during different age intervals up to 10 weeks. However, Iraqi et al., (2011) reported that heterosis for body weight ranged from to 9.05 after crossing Matrouh and Inshas chicken breeds. General and Specific Combining Abilities were significant (P≤0.05) for body weight from hatch to 10 weeks of age.
Crossbreeding is the mating of two individuals from different breeds, it is one of the tools for
exploiting genetic variation (Saadey et al., 2008; Momoh and Nwosu, 2008; Siwendu et al., 2012).
Diallel cross is the mating design of crossbreeding which is usually used to estimate heterosis,
general and specific combining abilities. According to Fairfull, (1990) heterosis is the increase in
characteristics of offspring over the average of its parents, general combining ability is an average
performance of an individual in a particular cross and the specific combining ability is a performance
of a parent under consideration in a specific cross.
OBJECTIVES
The objectives of this study was to estimate heterosis effect, general and specific combining abilities for body weight in a diallel cross between Ovambo, Potchefstroom Koekoek and Venda chicken breeds.
RESULTS AND DISCUSSION
MATERIALS AND METHODS
Study site: This study was conducted at the Experimental farm of the University of Limpopo, in the Limpopo Province of South Africa. The farm is located about 10km north-west of the Turf loop campus of the University of Limpopo.
Crossbreeding procedure and data collection:
9 Pens
All the chicks were measured using the weighing scale for body weight from hatching to ten weeks of age and also the mortality was considered in each pen.
Statistical analyses of the data:
Data was analyzed using the General Linear Model (GLM) procedure (SAS, 2008) according to the following linear model:
Yijk= µ + Gi + Hj+ Yk+ eijk
Yijk= the observation on the bird in the jth hatch of the ith breed group raised on the kth pen,
µ = the overall mean,
Gi= the fixed effect of the ithbreed group,
Hj= the fixed effect of the jth hatch
Yk= the fixed effect of the kth pen and
eijkl = the random error
Males V O P
Females
Conclusion
Heterosis estimates indicated that crosses between the Potchefstroom Koekoek sires and
Venda dams as well as between the Venda sires and Ovambo dams gave the highest
heterotic effect for body weight.