Haemoglobin polymorphism and its effect on different economic traits of Garole sheep

The Garole sheep is so far the only specialized sheep which is dwarf, highly prolific, has short lambing interval and is of coarse wool type. This sheep has specific characteristic of adaptability to hot and humid climatic conditions, grazing in knee-deep saline water and high mothering instinct for their neonates (Pan and Sahoo 2008). The genetically determined polymorphous system of haemoglobin in sheep provides an opportunities for using them as genetic markers that make it possible to conduct studies related to the genetic structure (Slavov et al. 2004). Although these genetic markers and their mode of inheritance were clarified in most sheep breeds, but for Garole sheep are rather limited. The objective of this research was to determine polymorphism of blood protein haemoglobin and also to determine the influences of haemoglobin on the performances of different economic traits of does. Adult Garole sheep (48 ewes and 24 ram) were selected randomly from the University farm stock during the period from April-September 2008. Data on economic traits, viz. number of lambs produced in first, second, third, average number of lambs produce per lambing, age at first lambing (days) and lambing interval (days) of Garole sheep were collected from farm. Blood samples were obtained by Jugular vein puncture, drawn into 5 ml tubes containing suitable anticoagulant. The blood was centrifuged at 6000 rpm for 15 min and the red cells were collected in a dry, aseptic glass vial and stored in deep freeze at about –20°C until used for electrophoresis. Electrophoretic examinations were done using a SDS-PAGE electrophoresis system for separating the hemoglobin types. Haemoglobin was typed by Andrew (1986). Identification of phenovariants was done on the basis of number of bands and mobility towards anode. Genotypes and gene frequencies were estimated by direct counting method. The departure from genetic equilibrium was measured by Chi square test. All statistical analysis was done by using the SPSS package. Effect of haemoglobin phenotypes on performance were analysed by least-square analysis of variance. The mean and standard error of the different economic traits under study were calculated and all tests for significance were done by following standard method. Three different haemoglobin types (Hb AA, Hb AB and Hb BB) determined by 2 alleles (HbA and HbB) were observed. It was found that Hb A and Hb B are most common alleles among various alleles known to be responsible for haemoglobin types in sheep. Both the alleles (Hb A and Hb B) were found in this study. These two alleles control the inheritance of haemoglobin type and give rise to 3 phenotypes, namely Hb AA, Hb AB and Hb BB. It was found that 23 animals had AA phenotype, 32 animals with phenotype AB and 17 animals with BB phenotype in all the animals studied (Table 1). The more frequent phenotype was the heterozygous Hb AB phenotype animal that constituted about 45% of the total population. The other 2 phenotypes, HbAA and Hb BB animals were 32 and 23%, respectively. Similar results were also observed by Ghatak (2001) in Garole sheep and Bindu and Raghavan (2010) in Malabari goat.