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ThesisItem Open Access Characterisation and evaluation of the dwarf cattle of Kerala(Department of Animal Breeding and Genetics, College of Veterinary and Animal Sciences, Mannuthy, 1994) Girija, C R; KAU; Sosamma, IypeThe native cattle of Kerala have been treated as non descript animals always eventhough they possess some special features. The dwarf cattle often called as Vechur were very popular in Central Travancore until 35 years back. With the emergence of the crossbred population of cattle the traditionally reared local cattle have gradually suffered genetic erosion. Under this circumstance, the present work was undertaken to characterize and evaluate the germplasm of local dwarf cattle of Kerala by studying (a) the karyotype and morphology of chromosomes using G-banding (b) the population structure by means of gene frequencies of different blood proteins (c) the growth and production performance. The characterization and the evaluation would help in finding out the genetic differences of the dwarf cattle which will help in deciding about the conservation of their germplasm as a reserve for the future. The dwarf cattle maintained under the ICAR scheme on “Conservation of germplasm of Vechur cattle of the coastal area and the dwarf cattle of the high ranges of Kerala” formed the material for the study. The characterization and evaluation was carried out through the cytogenetic, immunogenetic and polymorphism studies as well as through the description of the growth and production traits. Karyotype analysis was carried out using peripheral blood leukocyte culture technique described by Halnan (1977) and Halnan (1989) with suitable modifications. G-banding of chromosomes were done by the method described by Thiagarajan (1993). Blood protein polymorphism systems such as Haemoglobin and transferring were studied by poly acrylamide gel electrophoresis in horizontal dimension. (Gahne et. al. 1977) with suitable modifications. The statistical analysis of the growth and production data were done as suggested by Snedecor and cochran (1967). The diploid chromosome number of the dwarf cattle was found to be 60, with 29 pairs of autosomes and one pair of sex chromosomes. All the autosomes and the ‘Y’ chrosome were acrocentric. The X chromosome was submetacentric. The relative length of the autosomes ranged from 1.757 to 5.431 per cent. The relative length of the X and Y chromosomes were found to be 5.591 per cent and 2.875 per cent respectively. In the karyological array, the X chromosome occupied the first position. The X chromosome was biarmed and the arm ratio and centromere index obtained were 2.182 and 0.314 respectively. The karyotype and morphometric measurements resembled the finding in Bos indicus group of cattle. The G-banding pattern of chromosomes revealed 72 regions and 314 G-bands. The Y chromosome had 7 G-bands in the ‘q’ arm which resembled the ‘q’ arm of Bos taurus described in the international system for cytogenetic nomenclature of domestic animals. There were two haemoglobin variants HbA and HbB and three phenotypes viz. HbAA, ,HbAB and HbBB , in the population. The heterozygocity was found to be 0.4815. The population was found to be in genetic equilibrium with respect to the Haemoglobin locus. Six transferring phenotypes controlled by three alleles TfA, TfD and TfE were observed. The frequency of TfE (0.359) allele in the dwarf cattle was as high as the frequency of the allele reported in the zebu cattle. The absence of transferring variants like TfF, TfH, TfN and TfG and higher frequency of TfE allele are probably indicative of the genetic isolation of the population from exotic breeds. The absence of TfB and TfF allele which is present in Gir, Hariana, Kankrej, Kangayam, Ongole, Red Sindhi, Sahiwal and Tharparkar also indicates that the dwarf cattle has not inherited genes from the above cattle breeds. The body weights and measurements of calves at birth studied showed that the male calves had a higher body weight (12.55 ± 0.31 kg with a CV of 7.86 per cent) than female calves (10.78 ± 0.40 kg with a CV of 15.02 per cent). The same trend was observed with regard to the birth body measurements also. The heart girth measurement and body weight showed a positive correlation from birth to the 24th fortnight. There is a 100 per cent increase in the birth weight by the 5th fortnight and a three-fold increase by the 10th fortnight. The average daily gain in weight for the four periods I e., fortnights 0-6, 7-12, 13-18 and 19-24 were 0.160 ± 0.011, 0.167 ± 0.018, 0.212 ± 0.011 and 0.139 ± 0.015 respectively for female calves and 0.188 ± 0.023, 0.145 ± 0.016, 0.116 ± 0.025, 0.242 ± 0.049 kg respectively in male calves. During the period from birth to 6th fortnight the growth rates in males and females were similar. The gain in body weight per day during the periods from 7 to 12th and 13 to 18th fortnight was comparatively less for males but the trend reversed during the period of fortnights for 19 to 24th. The average body weights of adult females and males were 126.90 ± 3.56 kg (CV 16.39%) and 210 ± 15.75 kg (CV 14.95%) respectively. The body measurements such as length, heart girth and height (in cms) in females were 97.5 ± 1.12 (CV 5.85%), 115.60 ± 1.32 (CV 5.82%) and 87.53 ± 0.82 (CV 4.82%) respectively. The corresponding figures in males were 111.5 ± 3.77 (CV 6.76%), 146.0 ± 2.92 (CV 3.99%) and 107.5 ± 1.35 (CV 2.50%) respectively. The average body weights and measurements were lesser than those reported in other Indian breeds and crossbred cattle. The total lactation milk production performance of the dwarf cattle was 471.68 ± 38.72 kg (CV 45.29%) in an average lactation length of 217 ± 16.50 days (CV 32.20%). The average daily yield was 2.17 ± 0.11 kg (CV 29.48%). The dwarf cattle attained a peak yield of 3.71 ± 0.16 kg (CV 21.5%) in 23.23 ± 1.703 days (CV 37.38%). The milk production performance eventhough was lesser than crossbreds or some recognized Indian breeds, the milk production in comparison with the body size was reasonable. Considering the morphology of the Y chromosome, the Hb as well as Tf polymorphism and their allelic frequencies, it is to be summarized that the stock of dwarf cattle of Kerala maintained at Kerala Agricultural University is genetically isolated from the other cattle breeds of the country and world. The body size and milk production of the cow indicates its suitability for a farmer who requires milk just for home consumption. The study strongly confirms the necessity of conservation of the dwarf cattle of Kerala which is the smallest variety available in India and perhaps in the world itself.ThesisItem Open Access Parentage control in cattle using blood types(Department of Animal Breeding and Genetics, College of Veterinary and Animal Sciences, Mannuthy, 1992) Mary John, V; KAU; Nandakumaran, BImmunogenetic studies were carried out in four hundred and eleven cross-bred cattle maintained at the University Livestock Farm, Mannuthy and Cattle Breeding Farm , Thumburmuzhi The animals belonged to three genetic groups, viz Jersey cross breds, Brown-Swiss cross breds and Holstein Friesian cross breds The animals were typed for blood group factors and haemoglobin Blood group reagents were produced from iso immune sera, hetero immune rabbit sera and colostrum of an immunised cow Eleven reagents were produced by the above cited methods and seven of them were comparable to international reagents Serum from two animals (Animal Nos 248 and 743) were used as sources of anti J whose titres were being assessed periodically by haemolytic technique The titre varied from 0 to 1 32, but no association with seasons of the year, could be noticed Typing of cross bred animals was done with 28 blood group reagents (14 internationally comparable and 14 new reagents) The internationally comparable reagents were B, Y25 E 3 , C23 R, , F, V, J, L, S, H and Z Anti J from two different sources (Animal Nos 248 and 743) were used and one (Animal No 743) seemed to be the sub type of other (Animal No 248) Standard haemolytic test was carried out for typing animals for their blood group factors The factors occurred in the three genetic groups with varying gene frequencies A good agreement was observed between the observed and expected numbers in each genotypes with respect to FV locus in all the population except in Holstein Friesian cross breds (P < 0 05 ) The mode inheritance of blood group factors showed that the cattle red blood cell antigenic factors were inherited as dominant over their absence The cross-bred population was also typed for haemoglobin Electrophoresis was carried out in poly acrylamide gel Only two haemoglobin variants viz HbA and HbB and three phenotypes viz Hb AA, Hb AB and Hb BB were A observed The gene frequencies of Hb allele was 0 67, 0 6 6 and 0 83 m Jersey cross breds, Brown Swiss cross breds and Holstein Friesian cross-breds, respectively The genotype frequencies at haemoglobin locus for the pooled cross breds were 0 5036 (Hb AA), 0 4307 (Hb AB) and 0 0657 (Hb BB), respectively Genetic variability of breeds was studied m terms of heterozygosity at Hb locus and Friesian cross breds were found to have least heterozygosity, ie 0 282ThesisItem Open Access Biochemical polymorphism in broiler rabbits(Department of Animal Breeding, Genetics and Biostatistics, College of Veterinary and Animal Sciences, Mannuthy, 1990) Usha, A P; KAU; Mukundan, GBlood samples collected from rabbits maintained in the rabbit breeding farm of Kerala Agricultural University formed the materials for this study These blood samples were typed employing horizontal polyacrylamide gel electrophoresis to study the polymorphism of transferrin post transferrin and haemoglobin A total of 152 rabbits comprising of 50 Soviet Chinchilla 52 Newzealand White and 50 local rabbits were involved m the study Genetic inter relationship among growth traits and survivability were studied In all the genetic groups two transferrin variants the faster Tf and slower Tf with two phenotypes TfAA and TfAC were observed The gene frequency of Tf and Tf were 0 7500 and 0 2500 in Soviet Chinchilla 0 8300 and 0 1700 m Newzealand White and 0 8100 and 0 1900 m local rabbits The frequency of TfA allele was higher in all the populations The phenotype TfCC was not observed in any of the genetic groups Three post transferrin phenotypes Ptf FF Ptf FS and Ptf SS were detected and found to be controlled by two F S co dominant alleles Ptf and Ptf The fast moving F variant was designated as Ptf and the slow moving migrant S F was designated as Ptf The gene frequency of Ptf was 0 7400 0 8500 and 0 7600 m the three genetic groups and e that of Ptf was 0 2600 0 1500 and 0 2400 in Soviet Chinchilla Newzealand White and local rabbits respectively Haemoglobin was found to be monomorphic in all the three genetic groups studied The allelic frequencies of transferrin and post transferrin were suggestive of Hardy Weinberg equilibrium in the populations of three breeds No significant diversity was found to exist between genetic groups analysis of segretation pattern observed in pedigrees revealed the autosomal codominant mode of inheritance for transferrin and post transferrin alleles The absence of TfCC phenotype in the whole population of rabbits may be due to its unfavourable influence on the viabilityThesisItem Open Access Genetics of body dimensions of Malabari goats and its cross in Kerala(Department of Animal Genetics and Breeding, College of Veterinary and Animal Sciences, Mannuthy, 1994) Raj, Menon; KAU; Stephen, MathewThe main objectives of this study were: (1) to study the bodyweight and body dimensions of Malabari goats and its Alpine half breds, (2) to estimate the genetic and phenotypic correlations between bodyweight and different body dimensions in various genetic groups and (3) to study any other major factors affecting bodyweights and body dimensions. The study was conducted in 92 goat kids reared at the All India Co-ordinated Research Project on goats farm at Mannuthy, Thrissur. A comparative study was made on the native Malabari with its third generation cross with the exotic Alpine breed. The mean body length, heart girth and height at withers at birth wera 25.68 ± 0.53, 27.37 ± 0.46 and 29.66 ± O. 60 cm and 26.01 ± O. 16, 28.23 ± 0.23 and 30.24 ± 0.45 in male kids of Malabari and Alpine x Malabari crossbreds respectively. In the females the corresponding values were 25.63 ± 0.073, 27.56 ± 0.68 and 25.53 ± 0.48 and 25.3 ± 0.17, 27.60 ± 0.32 and 29.14 ± 0.35 cm. The mean body length, heart girth and height at withers of male Malabari and Alpine x Malabari goats at 60.39 ± 0.81, 59.66 ± 0.82 and 58.18 ± 0.91 12 months were 61.42 ± 0.90, 61.12 ± 0.90 and 59.04 ± 1 . 01 cm and 64. 19 ± O. 81, 64. 60 ± O. 73 and 61. 98 ± O. 9 cm respectively. The corresponding values for females were 58.36 ± 0.81,59.0 ± 0.7 and 58.36 ± 0.72 and respectively. There was no significant difference between the birth weights of- male and female Malabari kids and between the birth weights of the two genetic groups. But the difference was significant in the Alpine x Malabari crossbreds. There was significant difference in the bodyweight at 12 months of age between male and female Alpine x Malabari crossbred kids. No significant difference was observed in the bodyweight at 12 months between the two genetic groups. During the experiment period mean maximum and minimum temperature were 34.55 ± 1.2 and 22.03 ± 1.4 °c respectively. Season had a significant effect on the body weight at six, none and 12 months of age in Alpine x Malabari crossbreds. The effect of type of birth was not significant on the birth weights in Alpine x Malabari crossbreds and Malabari kids. Type of birth had no significant effect on the 12 months body weight in both the genetic groups. analysis showed non-significant Least squares effects of season and sex on the body weights in Malabari kids while in the Alpine x Malabari the effect of sex on body weights was significant at all the ages studied. Season at six, nine and 12 months of age had significant effects on bodyweight in Alpine x Malabari crossbreds Breed had no significant effect on body weights. The heritabilities of bodyweights at various ages were higher in Malabari when compared to Malabari x Alpine crossbreds. The highest phenotypic correlations were observed between the bodyweight and heart girth in both genetic Genotypic correlations between different groups. traits were found to be low at different ages in both the genetic groups. The highest coefficients of determination were observed at the age of six months for both the prediction equations.ThesisItem Open Access Genetics analysis of body weight and litter traits of pure bred rabbits(Department of Animal Breeding and Genetics, College of Veterinary and Animal Sciences, Mannuthy, 1992) Radhakrishnan, J; KAU; Mukundan, GThe experiment was carried out at the Rabbit Research Station attached to the Centre for Advanced Studies in Animal Genetics and Breeding, Mannuthy. Rabbits belonging to three pure breeds viz. Grey Giant, Soviet Chinchilla and New Zealand White formed the materials for the study. From each breed, seven males were taken and each male was mated to two females each and in all 14 females and seven males were considered in each breed. Seven parameters of reproductive efficiency of the dam were taken and body weights of rabbits born were recorded at four, six, eight, ten and twelve weeks of age. The mean values of body weight at four, six, eight, ten and 12 weeks were highest in Soviet Chinchilla rabbits compared to Grey Giant and New Zealand white, which had the lowest weights among the three breeds. Breed effect was significant for the body weight in all the weeks. The effect of sex on the body weight of rabbit was non – significant in all the three breeds. The sire of the offspring affected the body weight at each stage in all the three breeds. There was also a dam effect on body weight. In general the estimates of heritability were high in all the three breeds. The estimates of heritabilities for body weight show some marked effects of age. In particular, the pre – weaning weights had a high or moderate value compared with the lower estimates obtained for post – weaning weights. Estimates of heritability from the dam component revealed generally larger heritabilities than those of sire component except in New Zealand White rabbits. The phenotypic correlations between the body weights at different ages were positive and generally high, and tended to decrease in value as the differences between the two ages increased. The genetic correlations between body weights for the three breeds showed that all of these relationships were positive, like the corresponding phenotypic estimates. The environmental correlations were generally very high in all the three breeds except in Grey Giant rabbits when estimated based on (Sire + dam) method which may be due to sampling error. It was found that the effect of the breed on the gestation length was non – significant. The breed of the rabbit significantly affected the litter size at birth. Soviet Chinchilla breeds had the lowest litter size at birth. The effect of breed was gain highly significant for the litter size at weaning. Soviet chinchilla rabbits had the lowest litter size at weaning also. Maximum pre – weaning mortality was seen in the Soviet Chinchilla breed though the effect of the breed was found to be non – significant. The highest litter weight at weaning was seen in grey Giant rabbits and the lowest in the New Zealand White rabbits though the number of rabbits alive in New Zealand White breed were more than in the Soviet Chinchilla rabbits. The mean litter weight at weaning was highest in Soviet Chinchilla rabbits. The overall sex ratio was 52 percent. The estimates of heritability for the litter size at birth and at weaning were negative and hence adjusted to zeroThesisItem Open Access Chromosome characterisation of malabari goats and its crosses in Kerala(Department of Animal Breeding and Genetics, College of Veterinary and Animal Sciences, Mannuthy, 1992) Bindu, K A; KAU; Raghunandanan, K VThe chromosome profile of goats was studied with a view to find its number, to prepare the karyotypes of female and male goats of the Malabari and its crosses with Saanen and Alpine and to assess its morphometric values. The experiments were carried out in jugular blood lymphocytes. The cultures were prepared using RPMI 1640 as the medium. The comparative efficacy of different mitogens viz. PHA, PWM and their combination, with different incubation time, revealed that the combination of PHA and PWM at an incubation period of 70.5 h yielded the optimum results. The diploid number of chromosomes in all the genetic groups of goats were found to be 60. Autosomes as well as X chromosomes were found to be acrocentric. The X chromosome was quite prominent in being the longest of all. The Y chromosome was the shortest and the only metacentric in the complement. In karyotypes of the three genetic groups, it was observed that twenty-nine homologous pairs of autosome formed a closely graded seriation. Sexual dimorphism was exhibited with an unequal pair of X and Y chromosomes in males and an equal pair of X chromosomes in the females. The relative length was estimated for each pair of chromosomes in percentage. The X chromosome contributed to more than five per cent of the total complement length in all the three genetic groups. In Malabari, Saanen x Malabari and Alpine x Malabari, the relative length of the Y chromosomes were 1.552+0.10,1.321+0.09 and 1.548+0.10 respectively. The analysis of variance of relative length of X chromosomes revealed a significant difference among the three genetic groups.ThesisItem Open Access Genetic characterisation of buffaloes in Kerala using cytogenetic technique(Department Of Animal Breeding And Genetics, College Of Veterinary And Animal Sciences, Mannuthy, 1991) Anilkumar, K; KAU; Mukundan, GBuffaloes from four districts of Kerala formed the materials for this study. Blood samples were collected from external jugular/ear vein, in heparinised tubes. The technique employed was peripheral leukocyte culture technique. Out of the three different mitogens viz., pokeweed mitogen (PWM), phytohemaggultinin (PHA). and a mixture of these two. the mixture of PWM and PHA was found superior in inducing mitosis. A significant interaction between the mitogens and time of addition of mitotic arrester into the medium was observed. The mixture of PWM and PHA at an incubation time of 71 hours was found to produce best results in culture of buffalo lymphocytes followed by PWM at 70 hours. Ideal concentration of colcemid as mitotic arrester in this study was found to be 2 µg and 3 µg per ml of culture media, when the time of action of colcemid was retained for one hour. Out of the 54 animals studied 45 had 2n=50, 5 had 2n=48 and rest 4 had 2n=49. In all the three chromosome types of animals 10 submetacentric chromosomes were observed. The sex chromosomes were similar in all the three types. Number of acrocentric autosomes was 38, 36 and 37 in the three classes respectively. The buffaloes having diploid chromosome number of 49 had two non homologues submetacentric chromosomes, one being the largest of the whole complement and one acrocentric was without a pair. The longest submetacentric autosome of swamp type had a relative length of 6.925+0.152 whereas in river type it had a relative length of 7.228+0.094. The smallest submetacentric autosome was having an average relative length of 4.911+0.118 and 5.05+0.107 in swamp type and river type respectively. Relative lengths of longest acrocentric autosome in swamp type and river type were) 4.953+0.13 and 4.618 + 0.095 respectively. The shortest acrocentric in swamp type showed a relative length of 2.301+0.034 whereas in river type the shortest chromosome had a relative length of 2.064+0.275. The X chromosome was largest acrocentric chromosome of the complement. The Y chromosome was acrocentric and took a position of 22 in descending order based on relative length in the river buffaloes, whereas it occupied 20th position in swamp type. The X chromosome in swamp type had the relative length of 6.228 + 0.099 and that of river type was 6.220+0.136. The Y chromosome of swamp type and river type had relative length of 2.675+0.188 and 2.550+0.095 respectively. In terms of relative length X chromosome occupied fourth position in comparison to submetacentric autosomes of river type, whereas it was third position in swamp type. In swamp buffaloes arm ratio ranged from 1.479+0.055 in fifth to 2.183+0.169 in first submetacentric autosome. In river type the largest arm ratio was 2.289+0.221 in first chromosome and the smallest was 1.542+0.158 in fifth chromosome. The highest centromere index of 40.4+0.9 was obtained for fifth chromosome and the smallest centromere index of 33.2 + 2.1 was for first chromosome of swamp type. In river buffaloes fifth chromosome had a centromere index of 40.4+1.9 and first chromosome had the centromere index of 31.2+2.4. The observation of chromosome polymorphism in buffaloes of Kerala State have to be borne in mind prior to drawing breeding strategies in buffaloes for improved production potential and reproductive efficiency.ThesisItem Open Access Comparison of immune response of the indigenous and cross bred cattle of Kerala(Department of Animal Breeding and Genetics, College of Veterinary and Animal Sciences, 1994) Francis Bastin, P; KAU; Sosamma, IypeThis research work aimed at comparing the immune responses of indigenous and crossbred cattle of Kerala and finding out association if any, with common diseases and also maternal immune response and the neonatal calf diseases and mortality. Thirty adult local indigenous cattle, their 36 calves, 40 adult crossbred cows and their 40 calves formed the material for the study. Primary humoral response to the test antigen, human red blood cells was assessed at zero, seven and 14th day. Secondary immune response to the test antigen was assessed on day three, seven and 14 after booster injection at 14th day. The antibody titre was assessed by direct microhaemagglutination technique. Cell mediated immune response to contact sensitizer 2,4-Dinitrochlorobenzene (DNCB) was assessed by application of two per cent solution on zero and first day followed by percutaneous challenge at the 14th day. Double fold skin thickness and area of reaction were recorded. Humoral and cell mediated immune response, the influence of genetic group, association with diseases and mortality, influence of maternal immune response on the calf immune response and association with calf diseases and mortality were assessed. The antibody titres were expressed as 1oge + 1 to make the distribution normal. Peak primary immune response was reached by day 14 (2.13) and peak secondary response was on seventh day of secondary immunization (2.98). No significant differences were observed between primary and secondary immune response in different genetic groups namely indigenous and crossbred cattle and also in different age groups viz. dam and calf. The correlation between primary and secondary immune response except in indigenous cows, were highly significant. The cell mediated immune response peaked by 24th post 2,4-Dinitro chloro benzene challenge both in indigenous and crossbred cattle (7.0 mm). No significant association could be detected between the incidence of diseases and mortality with humoral as wel1 as cell mediated immunity. Similarly association between maternal and calf immune response was also not significant. Indigenous cows had lower incidence of respiratory diseases and mastitis compared to crossbred cattle (od2 = 3.8 and 19 respectively). Similarly local indigenous calves had significantly lower mortality (oc2 = 8). The results of the study suggests that primary immune response could be used as an index of secondary immune response. The study also suggests that immune response to a single antigen might not be indicative of general disease resistance. Further, apart from the immune response traits in the present study, there might be several factors which influence the immune response, disease resistance and disease susceptibility.ThesisItem Open Access Chromosome Profile Of Cross-Bred Bulls In Kerala(Department of Animal Breeding and Genetics, College of Veterinary and Animal Sciences, Mannuthy, 1994) Gopakumar, C P; KAU; Raghunandanan, KCytogenetic study was conducted on 53 young cross-bred (Bos Taurus x B. indicus) bulls stationed at the farm at Dhoni, belonging to Kerala Livestock Development Board. Young bulls included those selected for superior semen quality and others just started producing semen. The bulls were classified into Jersey cross, Holstein-Friesian cross and Brown-Swiss cross based on the paternal line. The semen quality and related attributes of the bulls were recorded, and the association between these traits and the karyological parameters were determined. Comparative chromosome study were performed in the three genetic groups. Metaphase spreads for staining and G-banding were obtained by peripheral leucocyte culture technique. The basal medium used for culturing was RPMI 1640 and mitosis was initiated in lymphocytes by a combination of phytohemagglutinin and pokeweed mitogen. The G-banding was done by incubating the chromosome spreads in 2 x SSC containing trypsin solution for 45 minutes at 660C. Karyological parameters such as chromosome number, morphology, relative length, arm ratio and centromeric index were studied. The nature, number and position of G bands were also examined. The reproductive attributes recorded included age at first semen collection age at freezable semen production, volume of semen, sperm concentration, total sperm output in first ten collections, number of ejaculates accepted for freezing and total freezable sperm output in first ten collections, and the morphological abnormalities of sperms. All the bulls except one, exhibited a diploid chromosome complement (2n=60, XY) in their cells. There were 29 pairs of acrocentric autosomes and a sub-metacentric x chromosome. The Y chromosome was sub-metacentric in Holstein-Friesian cross, and apparently metacentric in other two genetic groups. In one bull diploid/tetraploid mosaicism was observed with 6.67 per cent of lymphocytes carrying 120 chromosomes. The mean relative length of longest and shortest autosomes were 6.0174 ± 0.0273 and 1.6186 ± 0.0101 respectively. The X and Y chromosomes had a mean relative length of 5.5918 ± 0.0401 and 1.9636 ± 0.0396 respectively. In the X chromosome the arm ratio was 2.47 ± 0.04 and the centromeric index was 28.74 ± 0.33. A total of 405 bands were identified in the karyotype of the bulls. The G-banding pattern of cross-bred bulls in Kerala was not previously investigated, and hence the banding pattern observed in the study would be useful for cytogenetic screening of bulls in the state. On Analysing the semen quality and related attributes of the bulls it was found that one of the bull was oligospermic. The semen of this bull exhibited a high frequency of loose sperm heads. Semen of another bull was found to contain abnormal percentage of sperms with persistant proximal cytoplasmic droplet. A third bull produced semen in which the frequency of sperms with knobbed acrosome defect was very high. All the three bulls had produced ejaculates which were found unsuitable for freezing. The incidence of diploid/tetraploid mosaicism was detected in the bull producing sperms with knobbed acrosome defect. None of the ejaculates of this bull was suitable for freezing. However, further study was essential to conclude on the association between mixoploidy and knobbed acrosome defect or its influence on semen freezability. The other two bulls with seminal abnormalities exhibited cytogenetic profile similar as that of bulls producing normal semen. The effect of genetic group on the morphometry of sex chromosomes was found to be insignificant. However, the Y chromosome morphology was observed to be a suitable marker for identifying Holstein-Friesian crosses among the cross-bred bulls used for breeding in Kerala.