Hierarchical cluster analysis of yearling body weight and linear body measurements of sheep of Northern Nigeria and their crosses

Abstract

This study was conducted at the Sheep Project Unit of Small Ruminant Research Programme (SRRP) of National Animal Production Research Institute (NAPRI), Ahmadu Bello University, Shika, Zaria. Balami, Uda and Yankasa breeds (sheep of Northern Nigeria) were crossed . A total of 65 Yankasa, 23 Uda and 16 Balami ewes were served by 4 Yankasa, 3 Uda and 3 Balami rams. The diallel breeding pattern produced 192 lambs. However, only the 65 yearling that survived up to 12 months of age (yearling) were used for this study. The yearling body weight and linear body measurement data were analysed using General Linear Model (GLM) procedures of SAS with model that incorporated lamb genotype as fixed effects. Pairwise difference was used to separate the mean (SAS, 2003). Distances were used to construct dendrogram using the Unweighted Pairs Group Method Analysis implemented in R 2.13.0 package. TREE procedure that prints the dendrogram based on the distances between the clusters was introduced in PROC CLUSTER procedure. Yearling genotype affected body weight and all the linear body measurements considered in this study (P<0.05). The pure Balami yearling (BL X BL) had the highest birth weight at 12 months of age (29.10±4.02kg). Clumping structure of yearling body weight among sheep of Northern Nigeria and their crosses were grouped into two clusters at distance 2.656. Pure Balami (BL X BL) formed the first cluster while the rest of the genotypes belong to the second cluster. The second cluster was further divided into two sub-groups at 0.796. The first sub-group had yearlings from pure Uda (UD X UD), Uda ram and Yankasa ewe (UD X YK), Uda ram and Balami ewe (UD X BL), Balami ram and Uda ewe (BL X UD) and Yankasa ram and Uda ewe (YK X UD) at 0.514. Similar clumping structures with two clusters share among the nine genotypes at varied distances were recorded for all the linear body measurements studied. Patterns of similarities were established for yearling body weight and linear body measurements among sheep of Northern Nigeria and their crosses. Improvement plans for yearling growth traits of sheep in Nigeria should consider the genotypes with divergent genetic distances as sires and dams. This will ensure the best exploration of positive heterosis.