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Abstract Full Text

Relationship between phenotypic sexual characters and semen characteristics in four strains of cocks in northern Nigeria.


A study was carried out to evaluate the secondary sexual characteristics of four strains of cocks, comprising of two (2) exotics; Bovan Nera Black (BNB) and Isa Brown (ISB), one (1) improved local strain, Shika Brown (SB) and one (1) unimproved local strain, normal feathered cock (NFC). A total of 64 birds (16 for each strain) at 36, 38, 40 and 42 weeks were used for the study. The result indicated that shank length, comb length, comb width, wattle length and wattle width were all significantly (P<0.001) affected by strains, with the exotic strains being superior to the local cocks. Age Ă— strain interactions were also found to be significant. Phenotypic correlations between the secondary sexual characters were found to be significantly high and positive. The correlation between the secondary sexual characters and semen characteristics showed that shank length, wattle length and width, comb length and width had a positive correlation with semen volume (r=0.123, 0.335, 0.195 and 0.408 and 0.348 P<0.01), total sperm count (r=0.202, 0.300, 0.188, 0.403 and 0.320 P<0.05) and normal sperm (r=0.175, 0.143, 0.026, 0.155 and 0.065 P<0.05) respectively. Shank length has a positive correlation with sperm motility (0.010) and dead sperm (0.026), but a negative correlation with live spermatozoa. The result of this study shows a considerable similarity among the strains of cocks with respect to secondary sexual traits. Therefore, it may be inferred from this study that length of shank, comb and wattle are good predictors of semen attributes in male chickens. Selecting cocks with larger shank length, comb and wattle size can improve the semen quality and subsequently, results to higher fertility.