Multivariate analysis of sexual size dimorphism in local turkeys (Meleagris gallopavo) in Nigeria

Abstract

Sexual size dimorphism is a key evolutionary feature that can lead to important biological insights. To improve methods of sexing live birds in the field, we assessed sexual size dimorphism in Nigerian local turkeys (Meleagris gallopavo) using multivariate techniques. Measurements were taken on 125 twenty-week-old birds reared under the intensive management system. The body parameters measured were body weight, body length, breast girth, thigh length, shank length, keel length, wing length and wing span. Univariate analysis revealed that toms (males) had significantly (P < 0.05) higher mean values than hens (females) in all the measured traits. Positive phenotypic correlations between body weight and body measurements ranged from 0.445 to 0.821 in toms and 0.053-0.660 in hens, respectively. Three principal components (PC1, PC2 and PC3) were extracted in toms, each accounting for 63.70%, 19.42% and 5.72% of the total variance, respectively. However, four principal components (PC1, PC2, PC3 and PC4) were extracted in hens, which explained 54.03%, 15.29%, 11.68% and 6.95%, respectively of the generalised variance. A stepwise discriminant function analysis of the eight morphological traits indicated that body weight, body length, tail length and wing span were the most discriminating variables in separating the sexes. The single discriminant function obtained was able to correctly classify 100% of the birds into their source population. The results obtained from the present study could aid future management decisions, ecological studies and conservation of local turkeys in a developing economy.

Morphological and microsatellite DNA diversity of Nigerian indigenous sheep

“…Most researchers consider an organism’s phenotype as a multivariate set of variables and the covariation of traits an important analytical consideration [22]. Discriminant analysis of morphometric traits is a mathematical approach that has been widely used in determining the relationships between different breeds of livestock [6,23-25]. The most discriminating variables obtained in this study are similar to previous reports by Dossa et al [16] and Vargas et al [26].…”

Phenotypic characterization of the indigenous chickens &lt;i&gt;(Gallus gallus)&lt;/i&gt; in the northwest of Algeria

“…As for males, the third axis had a high contribution of beak length, which also represented an opposite direction between beak and wattle length. The present findings are consistent with the literature, in which general size is generally reported as the main factor of variation and thus constitutive of the first axis of PCA in chickens, rabbits, or turkeys (Shahin and Hassan, 2000;Ajayi et al, 2011;Egena et al, 2014). The principal component analysis allowed for better understanding of the complex correlations among the traits and reduced the number of traits, using only the three first PCs, without loss of information.…”

Correlation and path coefficient analysis of body weight and morphometric traits of two exotic genetic groups of ducks in Nigeria

“…The present findings are consistent with the report of Gois et al (2012) where male body weight and body measurements were found to be higher than those of females showing dimorphism in the domestic duck of Brazil. Similar findings had been reported by earlier workers in ducks (Teguia et al 2008;Yakubu 2011) and other poultry species (Ajayi et al 2012), suggesting that sexual dimorphism in ducks is manifested with respect to a large number of body attributes and in most breeds. This may be attributed to sex hormones which may promote larger muscle development in males than in females (Guni et al 2013).…”