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Kerala Agricultural University, Thrissur
The history of agricultural education in Kerala can be traced back to the year 1896 when a scheme was evolved in the erstwhile Travancore State to train a few young men in scientific agriculture at the Demonstration Farm, Karamana, Thiruvananthapuram, presently, the Cropping Systems Research Centre under Kerala Agricultural University. Agriculture was introduced as an optional subject in the middle school classes in the State in 1922 when an Agricultural Middle School was started at Aluva, Ernakulam District. The popularity and usefulness of this school led to the starting of similar institutions at Kottarakkara and Konni in 1928 and 1931 respectively.
Agriculture was later introduced as an optional subject for Intermediate Course in 1953. In 1955, the erstwhile Government of Travancore-Cochin started the Agricultural College and Research Institute at Vellayani, Thiruvananthapuram and the College of Veterinary and Animal Sciences at Mannuthy, Thrissur for imparting higher education in agricultural and veterinary sciences, respectively. These institutions were brought under the direct administrative control of the Department of Agriculture and the Department of Animal Husbandry, respectively. With the formation of Kerala State in 1956, these two colleges were affiliated to the University of Kerala. The post-graduate programmes leading to M.Sc. (Ag), M.V.Sc. and Ph.D. degrees were started in 1961, 1962 and 1965 respectively.
On the recommendation of the Second National Education Commission (1964-66) headed by Dr. D.S. Kothari, the then Chairman of the University Grants Commission, one Agricultural University in each State was established. The State Agricultural Universities (SAUs) were established in India as an integral part of the National Agricultural Research System to give the much needed impetus to Agriculture Education and Research in the Country. As a result the Kerala Agricultural University (KAU) was established on 24th February 1971 by virtue of the Act 33 of 1971 and started functioning on 1st February 1972. The Kerala Agricultural University is the 15th in the series of the SAUs.
In accordance with the provisions of KAU Act of 1971, the Agricultural College and Research Institute at Vellayani, and the College of Veterinary and Animal Sciences, Mannuthy, were brought under the Kerala Agricultural University. In addition, twenty one agricultural and animal husbandry research stations were also transferred to the KAU for taking up research and extension programmes on various crops, animals, birds, etc.
During 2011, Kerala Agricultural University was trifurcated into Kerala Veterinary and Animal Sciences University (KVASU), Kerala University of Fisheries and Ocean Studies (KUFOS) and Kerala Agricultural University (KAU).
Now the University has seven colleges (four Agriculture, one Agricultural Engineering, one Forestry, one Co-operation Banking & Management), six RARSs, seven KVKs, 15 Research Stations and 16 Research and Extension Units under the faculties of Agriculture, Agricultural Engineering and Forestry. In addition, one Academy on Climate Change Adaptation and one Institute of Agricultural Technology offering M.Sc. (Integrated) Climate Change Adaptation and Diploma in Agricultural Sciences respectively are also functioning in Kerala Agricultural University.
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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 Genetic studies on the immune response of broiler rabbits(Department of animal breeding and genetics, College of veterinary and animal sciences, 1995) Nandakumar, P; KAU; Mukundan, GThe scope and potential of broiler rabbit production as an alternate source of meat appears to be tremendous taking into account the unique biological attributes of rabbits. However breeding experiments utilising temperate breeds like Newzealand White and Soviet Chinchilla under the humid tropics of the state revealed heavy pre – weaning mortality, high incidence of diseases, sub optimal growth and reproduction. Indirect selection for diseases resistance has been proposed as the most viable approach and immune responsiveness has been suggested as one of the best indicators of disease resistance. Serum gammaglobulin (SG) level, Frossman antibody titer to SRBC, antibody reponse to BRBC, delayed type hypersensitivity (DTH) responses to intradermal injection of phytomitogen PHA – M, and contact sensitivity to DNCB challenge were assessed among 135 breeding rabbits below one year of age and belonging to Newzealand White and Soviet Chinchilla breeds. The effects of breed, sex, sire and body weight on the above immune traits were analysed. Heritability estimates were made for each of the above traits. Association of diseases like coccidiosis, mange and adult mortality with each of the above immune traits was worked out. Association of maternal immune trait status with litter traits was assessed. This research approach was aimed at developing an alternate breeding strategy in the indirect selection for disease resistance, growth and viability. SG level ranged from 9.13 to 84.70 mg/ml with a mean of 28.59 mg/ml. Soviet Chinchilla breed had a significantly (P= 0.048) higher SG level with a mean of 29.51 mg/ml compared to 27.25 mg/ml in Newzealand Whites, differences among males and females were not significant. Sire effects was not significant on SG levels and haritability estimate was 0.1259. Adult body weight had no significant effect on SG level among broiler rabbits. Association of SG level with litter size at birth was not significant. But SG level had a highly significant effect on the litter size at weaning. Correlation of SG level with pre – weaning mortality (- 0.430) was highly significant (P < 0.01) and negative litter weight at birth and at weaning were significantly correlated with SG level among broiler rabbits. No significant association could be observed between SG level and the incidence of mange and adult mortality. But a higher SG level among broiler rabbits was found to be significantly (P = 0.0440) associated with the incidence of naturally occurring coccidiosis. Presence of Frossman’s antibodies to SRBC was confirmed in adult rabbit sera. The Forssman antibody titer (1 + loge) ranged between 1.693 and 5.159 with a mean of 2.776. Breed and sex effects were not significant on Frossman antibody titer to SRBC. Effect of sire on this trait was not significant and the heritability estimate was 0.360. Frossman antibody titer had no significant effect on adult body weight, or litter traits among broiler rabbits. Correlations of Frossman antibody titer of the dam with the litter weight at birth, litter weight at weaning and pre – weaning mortality were not significant. No significant associations could be observed between Frossman antibody titer incidence of mange, coccidiosis and adult mortality. Pre – immunisation titer to BRBC among broiler rabbits was zero indicating the absecnce of Feossman antibodies to BRBC. Antibody titres to BRBC (1+ loge) were 4.594, 4.425 and 4.311 respectively at the first, second and third week post immunisation. The highest antibody response was at the first week, which began to decline gradually. The influence of breed and sex on the antibody response to BRBC were not significant during the first, second and third week post immunisation. Sire effect was highly significant on the antibody response to BRBC during the first, second and third week post immunisation in Newzealand White rabbits. The effect of sire on antibody responses to BRBC was not significant during the first and third week post immunisation in Soviet Chinchilla breed though it was significant during the second week post immunisation. The heritability estimates of antibody responses to BRBC were 0.9200, 0.9400 and 0.9067 respectively during the first, second, and third week post immunisation. The correlations of adult body weight with antibody responses to BRBC during the first, second and third week post immunisation were (-) 0.244, (-) 0.224 and (-) 0.216 respectively. The correlations were highly significant and negative. Antibody responses to BRBC during the first, second and third week post immunisation was not significantly associated with litter traits among broiler rabbits. The incidence of naturally occurring coccidiosis, mange and adult mortality was not significantly associated with antibody response to BRBC. The mean pre – injection skin thickness was 2.140 mm in Newzealand White and 2.224 among Soviet Chinchilla breed. The mean PHA responses at 24, 48 and 72 hours post injection were 2.259, 1.544 and 0.778 mm respectively. Breed effect was not significant on the pre – injection skin thickness or on the PHA responses at 24, 48 and 72 hours. The effect of sex was highly significant in the skin thickness with males having a thicker skin compared to females. The effect of sex on PHA responses at 24, 48 and 72 hours was highly significant with a female superiority for DTH responses to PHA – M. The effect of sires was not significant on pre – injection skin thickness. Sire effects were highly significant on the PHA responses at 24 and 72 hours and approaching near significance at 48 hours in Newzealand White rabbits. However, sire effect was not found to be significant on the PHA responses at 24, 48 and 72 hours post injection among Soviet Chinchillas. Heritability esimates for pre – injection skin thickness, PHA responses at 24, 48 and 72 hours were 0.7637, 0.8600 and 0.6370 respectively. Adult body weight was not significantly associated with the skin thickness and the PHA responses at 24, 48 and 72 hours. Litter size at birth was significantly less in thick skinned does, though weaning litter size was significantly higher in them. PHA responses at 24, 48 and 72 hours had no significant effect on litter size at birth and at weaning or any other litter traits. Pre – injection skin thickness and PHA responses at 24 and 72 hours were not significantly associated with the incidence of mange, coccidiosis and adult mortality. But reduced PHA response at 48 hours significantly pre – disposed the rabbits to body mange. Contact sensitivity to DNCB at 24, 48 and 72 hours post challenge averaged 3.585 mm, 1.796 mm and 1.085 mm respectively. Breed and sex had no significant effect on the contact sensitivity to DNCB at 24, 48 and 72 hours post challenge. Sire effect on contact sensitivity to DNCB at 24, 48 and 72 hours post challenge was not significant in Newzealand White rabbits. Among Soviet Chinchillas also effect of sire was not significant on contact sensitivity to DNCB at 24 and 72 hours, though highly significant at 48 hours. Heritability estimates for contact sensitivity to DNCB at 24, 48 and 72 hours post – challenge were, 0.3820, 0.5490 and 0.3039 respectively. Contact sensitivity to DNCB at 24, 48 and 72 hours post challenge was not significantly associated with adult body weight, litter size at birth and litter size at weaning. Contact sensitivity of the doe at 24 hours post challenge was positively correlated with pre – weaning mortality and litter weight at birth. Lowered contact sensitivity to DNCB at 24 hours had a highly significant effect on the incidence of naturally occurring body mange among rabbit. The incidence of mange was near significant level among broiler rabbits with a lowered contact sensitivity at 48 hours post challenge also. No significant association could be observed with contact sensitivity to DNCB at 24, 48 and 72 hours on the incidence of coccidiosis and adult mortality. Correlations between serum gamma globulin level and Frossman antibody titer to SRBC (0.271) was highly significant correlations of Frossman antibody titer with antibody response to BRBC during the first, second and third week post immunisation was also highly significant. Pre – injection skin thickness had a highly significant negative correlation with PHA responses at 24, 48 and 72 hours. Correlations among PHA responses at 24, 48 and 72 hours were highly significant. Similarly correlation among contact sensitivity reactions at 24, 48 and 72 hours post challenge were highly significant. PHA responses at 24, 48 and 72 hours had significantly high correlations with contact sensitivity to DNCB at 24, 48 and 72 hours post challenge. Prospects of utilising maternal serum gammaglobulin level as a marker in indirect selection for enhanced pre – weaning survivability and growth appears to be promising. Though increased SGlevel was found to be associated with the incidence of coccidiosis, further researches on the coccidial species and host defenses are before establishing a coccidiosis resistance phenotype associated with this trait. The differences in sire effects among the two breeds for antibody response to BRBC and PHA responses are suggestive of the genetic structure of the two breeds, especially the Soviet Chinchilla colony developed from few animals. The significant negative correlation of adult body weight with antibody responses are indicative of lower antibody responses in heavier rabbits. Strong negative correlations between PHA responses and pre – injection skin thickness and a significant effect of contact sensitivity at 24 hours on reducing the litter size at weaning appear to suggest that a low maternal cell mediated immunity might enhance pre – weaning survivability of the kits. Significantly higher incidence of mange among rabbits with a lowered PHA response at 48 hours post injection and contact sensitivity at 24 hours post challenge suggest of an enhanced cell mediated immune response conferring mange resistance.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.