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ThesisItem Open Access Milk protein polymorphism and milk composition in Vechur cattle(Department of Animal Breeding and Genetics, College of Veterinary and Animal Sciences, Mannuthy, 1996) Thirupathy Venkatachalapathy; KAU; Sosama, IypeThe native cattle of Kerala have been evolved through several generations of natural selection against high humidity, heavy rainfall and hot climate. They have been considered as non – descript animals, but there has been variety with characters distinguishing from others and known as Vechur Cattle of Kerala. The Vechur cattle had their origin in Vechur near Vaikom of Kottayam district of Kerala. They were very popular four decades back for their relatively higher milk production compared to other local cows. The extremely small size of the cow, good adaptation and high disease resistance are the traits very much favoured by the farmers. Farmers preferred Vechur cattle for ploughing in marshy lands because of the small size and light weight. The emergence of crossbreeding led to the gradual reduction in traditionally reared Vechur cattle. Under this circumstances, the present work was undertaken to characterise the Vechur cattle of Kerala by studying (a) certain genetic markers in milk (b) milk components like fat, total solids and solids not fat percentage (c) fat globule size and distribution and (d) iodine value. The Vechur cows maintained under the scheme on “Conservation of germplasm of Vechur cattle” formed the material for the study. Milk proteins such as casein and whey proteins were studied by polyacrylamide gel electrophoresis in horizontal dimension (Thompson and kiddy, 1963). The fat, total solids, solids not fat percentage of milk and iodine value of milk fat were estimated as prescribed by Indian Institution Standards. The fat globule size was measured under microscope by fitting an eye piece micrometer to the eye piece of the microscope. The statistical analysis were done as suggested by Snedecor and Cochran (1967). The influence of stage and time of milking were worked out using least squares analysis of variance as described by Harvey (1986). Three proteins α, β and k – casein were identified in casein system. At αsl – casein locus three phenotypes viz. BB, and CC determined by two allele B and C were observed. Frequency of CC phenotype (0.64) was highest a followed by BC (0.22) and BB (0.14). Frequency of B and C allele were 0.25 and 0.75. The β – casein locus consisted three phenotypes viz. AA, AB and BB with A and B allele. The frequency of AB phenotype was highest (0.57) followed by AA (0.29) and BB (0.14). Frequency of A allele was 0.57. At k – casein locus two phenotypes AA and AB with A and B allele were identified. The frequency of AB was (0.83) and frequency of A allele was 0.59. Two whey proteins α – lactalbumin and β – lactoglobulin were identified. At α – lactalbumin locus two phenotypes AA and AB with two allele A and B were observed. The frequency of AA and AB phenotypes were 0.57 and 0.43. The frequency of A and B allele were 0.78 and 0.22 respectively. The β – lactoglobulin locus consisted of three phenotypes viz. AA, AB and BB with A and B allele with frequency of 0.57, 0.29 and 0.14 respectively were identified. The frequency of A allele was 0.71. The frequency of C allele at αsl – casein locus was lower than the other Indian breeds like Sahiwal, Tharparkar, Red Sindhi and Rathi, but higher than exotic breeds like Jersey and Holstein and crossbred cattle of Kerala. The A variant at β and k – casein locus had frequency lower to other Indian breeds, exotic breeds of cattle and crossbred cattle of Kerala. The A variant at α – lactalbumin and β – lactoglobulin locus had much higher frequency than other Indian, exotic breeds of cattle of cattle and crossbred cattle of Kerala. B variant in vechur cattle was lower in frequency compared to other Indian breeds. The average milk fat percentage for 1 – 44 weeks of lactation was 5.95 + 0.12, 6.62 + 0.13 in the morning and evening respectively and the mean milk fat percentage for morning and evening milk was 6.23 + 0.19. The mean milk fat percentage at first week was 4.05 + 0.19, 4.65 + 0.17 and by 20th week of lactation was 5.92 + 0.08, 6.55 + 0.07 in the morning and evening milk respectively. The evening milk had uniformly higher fat percentage than morning milk. The fat percentage showed an increasing trend with advancing stage of lactation. The least squares means for morning and evening milk were 5.99 + 0.03 and 6.62 + 0.03 respectively and overall mean was 6.13 + 0.04. The mean total solids percentage of milk at first week was 12.64 + 0.17 and 13.57 + 0.19 in the morning and evening milk and it steadily increased to 14.75 + 0.13 and 15.31 + 0.18 in the morning and evening milk by 20th week of lactation. The average total solids percentage in milk from 1 – 44 weeks of lactation was 14.79 + 0.13 and 15.53 + 0.13 in the morning and evening respectively and the average for morning and evening together was 15.16 + 0.11 per cent. An increasing trend was noticed in total solids percentage as the lactation advanced. The evening milk showed uniformly higher total solids percentage compared to morning. The least squares mean was 15.02 and the adjusted mean for morning and evening was 14.85 + 0.05 and 15.55 + 0.05 percent. Least squares analysis of variance showed a significant effect of time of milking and stage of lactation on milk fat and total solids percentage of milk. The average solids not fat percentage from 1 – 44 weeks of lactation was 8.84 + 0.12 and 8.92 + 0.14 in the morning and evening milk respectively. The average for morning and evening milk was 8.88 + 0.13 and least squares mean was 8.90. The mean solids not fat percentage of milk at first week was 8.60 + 0.24 and 8.93 + 0.22. It was 8.83 + 0.11 and 8.76 + 0.15 percent at 20th week of lactation in the morning and evening milk respectively. No trend of increase was noticed in the solids not fat percentage in relation to the stage of lactation. The least squares analysis of variance showed no significant effect of time of miling and stage of lactation on solids not fat percentage. Total solids and solids not fat did not have strong association in general. The positive correlation between total solids and fat percentage were not significant. The negative correlation between fat and solids not fat percentage were also not significant. The milk fat and total solids percentage were higher than other Indian breeds of cattle, but lower to buffalo. The solids not fat percentage of milk was similar to other Indian breeds of cattle. The mean size of fat globule was 3.21 µ and the range was 2.54 to 4.07 µ. The mean diameter of fat globules was found to be 3.02 + 0.05 µ in the morning and 3.40 + 0.05 µ in the evening milk. The mean size of fat globules estimated in goat (Malabari and their crosses), crossbred cattle and Murrah buffalo were 2.60 µ, 4.87 µ and 5.81 µ respectively. The average fat globule size was found to be decreasing as the lactation advanced. The proportion of small size fat globules were found to be increased and the larger size of fat globules decreased towards the end of lactation. No correlation was noticed between fat globules size and fat percentage. The iodine value ranged from 28.61 to 30.29 and the average iodine value was 29.60 + 2.20. Based on available reports this appeared to be similar to buffalo, higher than goat and lower than cows. The size of fat globule (3.21 µ) was higher than the goat and lower to the other breeds of cattle and buffalo. Since the milk fat has higher production of smaller size fat globules and saturated fatty acids, it would be therapeutically useful in malabsorption syndromes due to its easy digestability. The larger proportion of small size fat globule is associated with high phospholipid content because of greater surface area. Phospholipids are important in the development of nervous system in babies. Thus Vechur cow milk appear to be suitable for infants and even sick. Studies on more number of cows are required for confirmation of results. It can be concluded that Vechur cattle of Kerala has unique characteristics of its own and have separate identity from other breeds of cattle not only by its small size but also due to its milk protein variants, composition of milk, size of fat globules and level of saturated fatty acids.ThesisItem Open Access Prevalence of yeast and yeast like fungi in bovine mastitis and their in vitro drug sensitivity(Department of Microbiology, College of Veterinary and Animal Sciences, Mannuthy, 1995) Sukumar, K; KAU; James, P CThe present investigation was undertaken to identify the the biochemical polymorphism at serum alkaline phospha tase (SAP) loci and to study the heterogenity of SAP variation in crossbred cattle It was also envisaged to analyse the association of SAP variation and traits of economic importance such as milk production and composition of milk One hundred and ten animals belonging to two different crosses of local nondescript cattle viz Crossbred Holstein Friesian (57) and Crossbred Brown Swiss (53) were typed for SAP variance by standardising Horizontal Polyacrylamide Gel Electrophoresis (PAGE) Two genotypes FS and SS were determined The highest frequency of FS genotype was in Holstein Friesian crossbred than in Brown Swiss crossbred The genotype FF was absent in both the crossbreds The highest frequency of SS genotype was in Brown Swiss crossbred than in Holstein Friesian crossbreds Two alleles namely pF and P$ with two phenotypes FS and SS were identified as SAP locus pT allele had the frequency of 0 20 and pS allele had the frequency of 0 80 in the pooled crossbreds Both the Holstein Friesian crossbreds and Brown Swiss crossbred are in genetic equilibrium at the SAP loci No association could be established between milk yield (305 days) and serum alkaline phosphatase level A non significant negative correlation existed between milk fat percentage and SAP level whereas a significant positive correlation existed between milk SNF percentage and SAP level The correlation between SAP level and milk total solids were found to be negative and non significant in Brown Swiss crossbreds whereas a non significant positive correlation existed between the SAP level and milk total solids in Holstein Friesian crossbreds Animals belonging to the FS genotype are better milk producers compared to the SS genotype For higher fat percentages the performance of SS genotype was compara tively better The performance of SS genotype is better for producing milk with more than 8 5 percentage of SNF FS genotype performed better for producing milk having higher percentage of total solidsThesisItem 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 Evaluation of holstein crossbred bulls based on milk composition of progeny(Department of Animal Breeding and Genetics, College of Veterinary and Animal Sciences, Mannuthy, 1997) Radhika, G; KAU; Sosamma IypeSire evaluation programmes in Kerala state, so far have been hinged around milk production alone, and no emphasis has been laid on milk constituents. The milk constituents like fat and solids not fat determined the market value and consumer's receptivity of milk. Reports on sire evaluation on the basis of milk constituents were seriously lacking in literature and hence the present investigation was undertaken with a view to compare the crossbred sires on the basis of milk yield, fat, total solids, and solids not fat percentages and their yields. 1284 milk samples belonging to 222 animals (103 progenies of Holstein crossbred bulls with superior genetic worth and 119 contemporaries) calved during the period 1995~96 formed the material for the study. These animals belonged to farmers in the area of six AI centres around Thrissur and also the animals maintained in three University Livestock farms. Milk samples were collected during early, middle and late lactation both in morning and evening, and the samples were analysed for fat, total solids and solids not fat percentages. Milk fat percentage was estimated by Electronic Milk Tester with frequent standardisation with Gerber's method. Total solids percentage was determined by Gravimetric method and solids not fat by finding the difference between total solids and fat percentages of milk. Fat, total solids and solids not fat yields were calculated by multiplying the percentages of these constituents with cumulative milk yield for each stage for lactation and adding. -- The statistical analysis was done as per standard procedure. Least squares technique as described by Harvey (1986) was employed to analyse the effects of centre, sire and season on the characters studied. The effect of centre was highly significant, while effects of sire and season were non- significant. The overall average 305 day milk yield was found to be 1829.68 kg. The progenies in the first lactation had higher averages compared to the contemporaries in different parities. Among the centres progeny average of 305 day milk yield was maximum for University Livestock Farm, Mannuthy (2800 kg) followed by Ramavarmapuram (2426.71 kg). University farm milk samples revealed higher values for 305 day milk yield, fat, total solids and solids not fat percentages compared to field milk samples. Among the centres, Arimbur recorded comparatively higher fat percentages during all stages of lactation. An important result from legal point of view was that,66.67 per cent of cows in the early stage of lactation, recorded morning milk fat per cent below the legal standards of 3.5. In case of solids not fat, 46.5 per cent were below the PFA standard of 8.5 per cent. Total solids and fat percentage showed an increasing trend with the progress of lactation. But such a trend was not observed for solids not fat percentage. Heritability estimates were calculated by paternal half-sib method for milk yield and its composition. Milk fat percentage had the highest heritability estimate of 0.326iO.234. The estimates of sire merit of Holstein Friesian test bulls for 305 day milk yield.fat, total solids and solids not fat percentages and yields, were computed by three methods of sire evaluation viz., daughter's average, contemporary comparison and least squares means. The yield characteristics were found to have more genetic variance than the corresponding percentages and hence preferred for sire evaluation. Since there was slight difference in the ranking of sires by these methods there is a need to study the accuracy of evaluation by different methods and then to choose the best method for evaluation under field conditions. The observation on the low milk fat and solids not fat percentages pinpoints the necessity of urgently amending PFA act for the benefit of the farmers.ThesisItem Open Access Genetic polymorphism of milk proteins in goats(Department of Animal Breeding and Genetics, College of Veterinary and Animal Sciences, Mannuthy, 1996) Raja, T V; KAU; Nandakumaran, BThe present investigation was undertaken to identify the biochemical polymorphism at different milk protein loci and to establish their inheritance pattern in Malabari and its exotic cross viz., Alpine X Malabari. It was also envisaged to analyse the association of different milk protein variants with lactation milk yield. Hundred goats belonging to Malabari (50) and Alpine X Malabari (50) were typed for milk protein variants employing horizontal Polyacrylamide Gel Electrophoresis (PAGE). The milk protein loci studied were Alpha S1 casein, Alpha S2 casein, Beta casein, kappa casein and Beta lactoglobulin. Two Alpha S1 casein variants, the faster Alpha S1 casein F and the slower Alpha S1 casein S with three phenotypes Alpha S1 casein AA, Alpha S1 casein AB, and Alpha S1 casein BB were observed. S allele had the frequency of 0.52 in Malabari and 0.70 in Alpine x Malabari crossbreds. The gene frequency of Alpha S1 casein F and Alpha S1 casein S were 0.48 and 0.52 in Malabari and 0.30 and 0.70 in Alpine X Malabari crossbreds, respectively. The frequency of S allele was higher in both the populations. Alpha S2 casein locus exhibited three phenotypes viz., AA, AB abd BB controlled by two allels A and B. A allele had the higher frequency of 0.71 in Alpine x Malabari crossbreds compared to 0.62 in Malabari. Higher frequency of AA phenotype was found in Alpine x Malabari (0.52) and that of AB phenotype in Malabari (0.44). Two alleles namely A and B contributed three phenotypes viz., AA, AB and BB at the beta casein locus in both the populations studied. Malabari showed higher frequency of B allele (0.55) while Alpine x Malabari had higher frequency of A allele (0.60). Beta casein AB phenotype had higher frequency in Malabari breed (0.54). Kappa casein locus showed two alleles A and B contributing three phenotypes viz., AA, AB and BB. The frequency of A allele was higher in both the population. The phenotype AA was higher in Alpine X Malabari crossbreds (0.56) while Malabari had higher frequency of AB phenotype (0.48) Two alleles namely A and B with three phenotypes AA, AB and BB were identified at Beta lactoglobulin locus. The phenotype AA was dominant in Alpine x Malabari crossbreds (0.50) and the frequency of BB phenotype was almost similar in both Malabari and Alpine x Malabari crossbreds (0.14 in Malabari and 0.12 in Alpine x Malabari crossbreds). The gene frequency of Beta lg A was found to be 0.65 in Malabari and 0.67 in Alpine x Malabari crossbreds. Both the populations studied were in genetic equilibrium with respect to these milk five protein loci. No significant diversity was found to exist between genetic groups. The genetic variability in the populations was calculated by estimating the heterozygosity. The overall heterozygosity in different populations indicated that the Malabari breed had comparatively higher degree of herozygosity (0.4711) followed by Alpine x Malabari crossbreds (0.4209). In Malabari maximum heterozygosity was observed at Alpha S1 casein loci (0.4992). In Alpine x Malabari maximum heterozygosity was observed at Beta casein locus (0.4800). The study of association between the genes controlling synthesis of milk protein showed significant association between the Beta casein with the Beta lactoglobulin Bb types in Alpine x Malabari crossbreds. All the other combinations of genes did not show any significant association. Milk protein variants were not found to be associated with the lactational yield (120 days) of the goats. The present study could establish the existence of biochemical polymorphism at Alpha S1 casein, Alpha S2 casein, Beta casein, Kappa casein and Beta lactoglobulin loci in Malabari and Alpine x Malabari crossbreds studied.ThesisItem Open Access Milk protein genetic variants in crossbred dairy cattle(Department of Animal Breeding and Genetics, College of Veterinary and Animal Sciences, Mannuthy, 1995) Madhavan, K; KAU; Nandakumaran, BThe present investigation was undertaken to identify the biochemical polymorphism at different milk protein loci and to establish their inheritance pattern in crossbred cattle. It was also envisaged to analyse the association of different milk protein variants with lactation milk yield and incidence of mastitis. One hundred and thirty five animals belonging to three different crosses of local nondescript cattle viz. crossbred Jersey (50), crossbred Brown Swiss (45) and crossbred Holstein Friesian (40) were typed for milk protein variants by standardising horizontal polyacrylamide gel electrophoresis. The milk protein loci studied were α S1 – casein, β – casein, k- casein and β – lactoglobulin. Two alleles namely B and C with three phenotypes BB, BC and CC were identified at α S1 – casein locus. B allele had the frequency ranging from 0.61 to 0.63. β – casein locus exhibited three phenotypes contributed by two allels A and B. A allele had the highest frequency of 0.81 in crossbred Brown Swiss and it ranged from 0.71 to 0.81 among different crossbreds. Highest frequency of AA phenotype was in crossbred Brown Swiss (0.67) and that of AB phenotype was highest in crossbred Jersey (0.29). Two alleles namely A and B contributed three phenotypes viz., AA, AB and BB at k - casein locus among different crossbreds studied. Crossbred Jersey showed the highest frequency of A allele while crossbred Brown Swiss (0.69) had the highest frequency of B allele (0.44). K – casein AA phenotype had the highest frequency in crossbred Jersey (0.52) and AB phenotypes had the highest frequency in crossbred Brown Swiss (0.51). β – lactoglobulin locus showed two alleles A and B contributing three phenotypes viz., AA, AB and BB. The frequency of A allele was highest in crossbred Holstein Friesian (0.46) and that of B allele in crossbred Brown Swiss (0.60). AA phenotype had the highest frequency in crossbred Holstein Friesian ( 0.25) while crossbred Jersey had the highest frequency of BB phenotype (0.38) and AB phenotype was highest in crossbred Brown Swiss (0.44). The observed and expected phenotypes among different genetic groups at all the four milk protein loci viz. αS1 – casein, β – casein k – casein and β – lactoglobulin were tested by Chi – square test. All the populations studied were in genetic equilibrium with respect to these four loci. This trend is suggestive of neutral role of the three milk protein loci in the population. The genetic variability in the crossbred population was calculated by estimating the heterozygosity was at β – lactoglobulin locus. In the crossbred Brown – Swiss maximum heterozygosity was seen at the k - casein locus. The overall heterozygosity in different crossbred population indicated that the crossbred Holstein Friesian had comparatively highest degree of heterozygosity (0.4603) followed by Crossbred Jersey (0.4346). In crossbred Jersey αS1 – casein types showed significant association with β – casein types. k – casein phenotypes were significantly associated with β – lactoglobulin types. In crossbred Brown Swiss also αS1 – types were found to be linked with β – casein types. β – casein BB phenotype and k – casein variants were found to be linked. β – lactoglobulin phenotypes and β – casein types were also found associated in crossbred Brown Swiss. In the case of crossbred Holstein Friesian all the milk protein variants except β – casein and k – casein were found to be associated. Milk protein variants were not found to be associated with first lactation milk yield or the incidence of mastitis in all the crossbred population studied. The present study could establish the existence of biochemical polymorphism at αS1 – casein, β – casein k – casein and β – lactoglobulin loci crossbred Jersey, crossbred Brown Swiss and crossbred Holstein Friesian cattle studied.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 zero