ABSTRACT

In this study to determine general and specific combining ability, reciprocal effect and heterosis, three breeds of rabbits namely New Zealand White (NZW), Dutch (DT) and Chinchilla (CH) were used. Each breed consisted of three does and one sire mated in thU diallel crosses. Seventy-two kittens resulted from the crosses. Preliminary analysis showed that the effect of genetic group was significant. Consequently, adjustments were made for fixed factors and diallel analysis was carried out. General combining ability V(GCA) was shown to be an important source of variation in four parameters out of twelve parameters studied in this experiment. These parameters are body length (BL), heart girth (HG), ear length (EL) and tail length (U) and their (ICA values are as follows: - 0.825, 0.000 and 0.825 for NZW, DT and CH, respectively for BL; -0.475, -0.099 and 0.575 for NZW, DT and CH, respectively for HG. EL had values of —0.248, -0.047 and 0.295 for NZW, DT and CII, respectively while GCA for U was —0.266, 0.101 and 0.164 for NZW, DT and CH, respectively. Specific combining ability was an important source of variation for only one trait, that is, head-to-shoulder (HS). Its values are as follows: 0.067 for NZW x DI, 0.100 for NZW x CH and 0.060 for DT x CH. Reciprocal effect was not significant (P>0.05). NZW x DT crosses had positive reciprocal effect for all the traits measured. NZW x CH crosses had positive reciprocal effects for all the traits with the exception of body width (BWH) (-0.850), HG (-0.205), LEL 0.1 10) and TEL (-0.055). The reciprocal effect in DT x CH for all traits, except HS (-0.075), BWT (-11.780) and HLH (-0.250), were positive. NZW x DT crosses showed negative heterosis for all the parameters measured, except HS (4.81), BWH (0.06), HG (4.21), HW (1.09) and EL (8.90). In NZW x CH crosses, heterosis was negative for all traits except HW (1.18) and LHL (1.76), while in DT x CH crosses, heterosis was positive for all the traits except LFL (-6.73). The range of the positive heterosis in DT x CH is —6.81 (LFL) to 23.41 (TL). The significant GCA indicates the presence of additive genes and that improvement in BL, HG, EL and TL could be achieved through selection and pure breeding. Chinchilla breed has a preponderance of additive genes and is recommended for crossing other breeds. NZW x CH crosses could be genetically used in improving HS, BWT, BWH, HG LHL and TL, whereas DT x CH crosses would be useful in improving BL, HW, ST, EL, HC and LFL as they were highest in SCA. Crossing could be genetically useful in improving traits especially in DT x CH. Significant and positive SCA is an indication of non-additive action, which invariably means that improvement in HS could be sought through crossbreeding of specific breeds. The non-significant reciprocal effects indicate that any breed can serve as male or female without sacrificing much of the genetic potentials. The level of heterosis indicates that crossing improved some traits, especially in DT x CH cross.