www.scholarsresearchlibrary.com t Available online a Scholars Research Library Annals of Biological Research, 2013, 4 (8):253-256 (http://scholarsresearchlibrary.com/archive.html) ISSN 0976-1233 CODEN (USA): ABRNBW 253 Scholars Research Library Genotype variation, age and body condition score on some paired testes measurements among common indigenous bull cattle breeds in Mubi Adamawa State, Nigeria P. A. Addass 1* , A. Midau 1 , Yahya M. M 2 . and M. A. Tizhe 1 Universitity of Agriculture Makurdi, Department of Animal Physiology, Breeding and Genetics, Benue State Nigeria 2 Adamawa State University, Animal Production Department, Mubi Adamawa State, Nigeria 3 Federal University of Technology Yola, Department of Animal Science and Range Management, Nigeria 4 Federal Polytechnic Mubi, Department of Animal Production and Health, Adamawa State, Nigeria _____________________________________________________________________________________________ ABSTRACT The four common breeds of cattle in Nigeria: Rahaji (RJ), Bunaji (BJ),adamawa Gudali (AG) and Sokoto Gudali (SG) were assessed for variation in testicular measurements the variation due to breed, year, age and body condition score (BCS). Significant (P<0.001) genotype variability were observed on all the paired testes parameters indicating RJ bulls having the highest followed by BJ, SG and AG. Paired intact testes weight (P1TW) values were: 486.46± 10.29g, 464.94±9.51g, 358.86± 9.2g and 296.88± 9.78g respectively. The corresponding paired intact testes volume (P1TV) values were 491.45± 10.30cm 3 , 457.23±9.52cm 3 , 359.48±9.93cm 3 and 295.12±9.78cm 3 , paired testes weight (PTW) values were 464.99±8.81g, 431.14±8.15g, 325.08±8.50g and 270.40±8.38g. Respective paired testes volume (PTV) values were 456.67±9.28cm 3 , 322.77±8.94cm 3 and 268.23±8.82cm 3 ; for net paired testes weight (NPTW) were 433.22±8.52g, 399.58±7.88g, 294.10±8.22g and 241.73±8.10g. Corresponding net paired testes volume (NPTV) values were 431.20±8.63cm 3 , 398.42±7.98cm 3 , 295.12±8.32cm 3 and 240.41±8.20cm 3 while the scrotal circumference (SC) values were 31.44±0.15cm, 30.22±0.14cm, 29.96±0.15cm and 29.59±0.14cm. Generally however, RJ bulls were found to have highest paired testes measurement followed by BJ and SG while AG had the least. Age group ≥ 4years recorded the highest values while age group 2 1 / 2 – 3 years had the least. Body condition score of 5 had the highest values followed by 4, 3 and 2. Key words: Breed; bulls; testes measurement; body Score condition (BSC). _____________________________________________________________________________________________ INTRODUCTION Natural breeding is still the most common procedure used in beef cattle operations throughout the world, although artificial technologies for cattle breeding are rapidly improving (Chenoweth, 1999). Where natural breeding is employed, the reproductive capabilities of bulls assume great importance. Herd’s reproductive rates are greatly influenced by both bull fertility and management. One of the most important factors influencing the profitability of a beef operation is the percentage of the calf crop weaned which is in turn determined mainly by the number of cows bred during the breeding season. Since the bull has more genetic influence (80-90%) of calves he sires, bull fertility selection can be the most powerful method of improvement in the herd. Accordingly loss of fertility by a bull can