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ThesisItem Open Access Marker assisted selection for milk production traits in vechur cattle(Department of Animal Breeding and Genetics, College of Veterinary and Animal Sciences Mannuthy, 2005) Shymaja, Uthaman; Raghunandanan, K VThesisItem 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 Evaluation of boer halfbreds for development of meat goat strains suited for Kerala(Department of Animal Breeding and Genetics, College of Veterinary and Animal Sciences, Mannuthy, 2004) Jeeva, L; KAU; Nandakumar, PThe tremendous potential of goat production in Kerala State is constrained due to the non-availability of meat type of goats suited to our climatic conditions. Malabari goats native to Kerala and improved Alpine Malabari (AM) grows to around only 8.5 and 11 kg respectively, imposing severe restrictions on commercial exploitation of these breeds. Introgression of Boer inheritance into Australian feral goats has led to the development of Australian goat meat industry and utilization of Boer goats to improve local goats in Maharashtra has paid rich dividend. With this background, the present investigation undertaken in Alpine Malabari crosses (AM) by infusing Boer inheritance was undertaken at University Goat and Sheep Farm was to evaluate the suitability of Alpine Malabari x Boer (AMB) crosses as a meat strain suited to Kerala State. Data on one hundred goat kids, 50 each belonging to 2 genetic groups, AM and AMB were subjected to least squares analysis to resolve the effect of genetic group, sire, month of birth and sex on type of birth, litter weight at birth, birth weight, body weight at first, second, third, fourth, fifth and sixth month, pre- weaning mortality, incidence of neonatal diseases, litter size at weaning, average daily gain in body weight, phenotypic correlation, viability and adaptability. Average litter size at birth (LSB) among Alpine Malabari (AM) and , Alpine Malabari x Boer (AMB) kids was 1.79±0.48. Alpine Malabari kid had a significantly (P:S0.05) higher litter size ~t birth of 2. I 2±0. I 6. Month of birth had a highly significant (P~O.OI) effect on litter size at birth with highest litter in July (2.2±0.17). Sire influences were highly significant on litter size at birth while sex had no significant influence on litter size at birth. Mean litter weight at birth was 3.77 kg and it was not found to be significantly affected by genetic group and sex. Month of birth and sire had highly significant associations with litter weight at birth. Alpine Malabari x Boer kids had a highly significant (P::::O.Ol) and higher body weight from birth to sixth month of age. Body weight in AMB kids was 2.38,6.01, 8.92 and 11.65 kg while AM kids had only 1.8,2.87,3.05 and 4.30 kg respectively at birth, one, two and three months respectively. Buck had a highly significant influence on birth weight of kid and body weight at first, second and third month. Month of birth had a significant influence on birth weight and body weights at first, second and third month. Incidence of enteritis was 0.31, respiratory infection 0.08 and pre- weaning mortality was 0.07. Effects of genetic group and sire were significant on respiratory infections and not on incidence of enteritis and pre-weaning mortality. Month of birth did not exert significant influence on respiratory infections, enteritis or pre-weaning mortality. The mean body weights at fourth, fifth and sixth month in AM and AMB crosses were 10.34 kg, 11.96 kg and 13.68 kg respectively. The effect of genetic group on body weights at fourth, fifth and sixth month was highly significant and superior in AMB crosses with 13.62 kg, 15.73 kg and 17.79 kg respectively while it was only 5.76 kg, 5.84 kg and 6.81 kg respectively in AM crosses. Sire effects were highly significant on the body weights at fourth, fifth and sixth month. Month of birth contribute to the body weights to a highly significant level and kids born in April and December were found to have higher body weights from fourth to fifth month. Sex of the kids was not found to influence the body weights from fourth to sixth month. The mean average daily gain in body weight (ADG) from birth to third month was 7r.36 g, from third to sixth month was 65.7 g and birth to sixth month was 66.7 g. AMB crosses had a highly significant ADG of 104.89 and 86.58 compared to 35.19 and 39.1 g during 0-3 and 0-6 month respectively. Sire influences were highly significant on ADG from 0-3 and 0-6 month. Month of birth had a highly significant effect on ADG and highest ADG was for kids born during April. Birth weight had a highly significant positive correlation with average daily gain in body weight from birth to third month and average daily gain in body weight from birth to sixth month and body weights from first to sixth month. Correlation between respiratory infections and pre-weaning mortality were highly significant. Average daily gain in body weight from birth to third month had a highly significant negative correlation with respiratory infection and pre-weaning mortality. Significantly higher litter size at birth in AM crosses over AMB crosses direct to the feasibility of AM genotype of enhancing litter size at birth which might partially be also contributed by use of oestrus synchronization on frozen semen technology in production of AMB crosses. Modulation of litter size at birth by month of birth reflect on the environmental factors influencing the ovulation rate, conception rate and embryonic survival. Monthly body weights from birth to six months was found to be highly superior in AMB crosses indicating the Boer superiority in enhancing body weights of AMB crosses. Significant effect of sire on these trait suggest of the additive genetic effect which might improve body weight in Boer crossbred goats. Contribution of month of birth on bodyweight probably influenced by ambient temperature, availability of biomass, offers potential for improvement of these traits by appropriate managemental strategies. Increased incidence of diseases in AM genetic group with higher pre-weaning mortality is worth for further investigation. ADG 0-3, ADG 0-6 were significantly higher in AMB crosses highlighting the importance of Boer development in improvement of growth rate of goats. The role of month of birth in variations in ADG partially reflect on the environmental conditions can adversely affect the growth rate. Phenotypic correlations, which were positive and highly significant between birth weight, ADG and body weight are suggestive benefits of early selection on birth weights for enhanced, slaughter weights. The negative correlation of ADG and incidence of pneumonia, pre- weaning mortality and enteritis could be used for the development of goats adapted to local climatic conditions.ThesisItem Open Access Genetic polymorphism of major histocompatibility complex class II genes(Department of Animal Breeding, Genetics and Biostatistics, College of Veterinary and Animal Sciences, Mannuthy, 2010) Remya John, v; KAU; Raghavan, K CThesisItem Open Access Beta lactoglobulin polymorphism in goats of Kerala(Department of Animal Breeding, Genetics and Biostatistics, College of Veterinary and Animal Sciences, Mannuthy, 2010) Sudina, K; KAU; Bindu, K.AΒeta-lactoglobulin gene polymorphism and its association with various milk production traits were investigated in DNA samples isolated from blood of 20 Malabari, 25 Attappady black 30 crossbred goats of University goat farm and 45 Malabari goats from the native tract of Malabari breed. Study was conducted by PCR-RFLP using Sac II restriction endonuclease. Digestion of the amplified PCR product with Sac II restriction endonuclease revealed three genotypes (S1S1, S1S2 and S2S2) in Malabari, Attappady black and crossbred goats, indicating the presence of S1 (349 and 77 bp fragments) and S2 (426 bp fragment) alleles. The S1/S2 allele frequencies were 0.37/0.63, 0.34/0.66 and 0.18/0.82, respectively in Malabari, Attappady black and crossbred goats. The genotypes of β-LG/Sac II polymorphism were distributed according to Hardy-Weinberg equilibrium with frequencies 0.04 (S1S1), 0.60 (S1S2) and 0.36 (S2S2) in Attappady black and 0.10 (S1S1), 0.17 (S1S2) and 0.73 (S2S2) in crossbred goats under study. But the Malabari goat population under study with genotype frequencies 0.14 (S1S1), 0.46 (S1S2) and 0.40 (S2S2), was found to violate H-W equilibrium. So this population was further classified and genotypic frequencies of subpopulations like Tellicherry (0.14, 0.50, 0.36), Badagara (0.2, 0.25, 0.55) and University farm (0.09, 0.61, 0.30) populations were in Hardy-Weinberg equilibrium. From the present study a significant association could be detected between β-LG polymorphism and peak milk yield in Malabari breed but not in other groups. Malabari goats carrying S2 allele showed a significantly higher average (p<0.05) (420±74.24 ml and 501.79±46.47 ml) compared to animals homozygous for S1 allele (250±13.36 ml). A statistically significant association could not be established between β-LG polymorphism and other milk production traits. So the introduction of this polymorphism can complement current selection programme.ThesisItem Open Access Cloning and sequence analysis of the growth hormone gene in Indian elephants(Department of Animal Breeding, Genetics and Biostatistics, College of Veterinary and Animal Sciences, Mannuthy, 2009) Bhosale, R A; KAU; Aravindakshan, T VThe study was undertaken with the objectives of cloning and sequence analysis of the growth hormone gene of the Indian elephants. The growth hormone is a peptide hormone produced in the anterior pituitory. It stimulates the growth of vertebates. It is a protein hormone of about 190 amino acids, synthesized and secreted by cells called somatotrophs. Growth hormone is a major participant in the control of several complex physiologic processes, including growth and metabolism and it is also of considerable interest as a drug used in both humans and animals. The genomic DNA was isolated from blood samples and a 1712 bp fragment of the entire transcriptional unit of the GH was amplified by PCR using synthetic oligonucleotide primer pair designed based on the 5′ and 3′ flanking sequences of goat growth hormone gene. The gel purified PCR product was ligated in to the pGEM®-T Easy cloning vector and was transformed by giving heat shock to competent E. coli cells prepared by CaCl2 treatment. The recombinant clones among the transformed cells were identified by Blue–White Screening and the recombinant plasmid carrying the insert gene was isolated from the white clones by a modified SDS-alkaline lysis method. The 1.712 kb GH gene insert in the vector was sequenced by the dideoxynucleotide sequencing method with primer walking using an automated DNA sequencer. The nucleotide sequence showed 75 to 96 per cent homology with pig and 77 to 95 per cent with that of Dolphin GH genes, respectively. The exon-intron boundaries in the porcine gene occur at the codons of the amino acid residues, Gly-4 (intron 1), Phe-57 (intron 2), Ser-96 (intron 3) and Arg-150 (intron 4). The all four residues are conserved in both species and also in African elephants. This strict homology in the sites of insertion of introns suggests that the exon-intron organization of these genes was established before the divergence of these species. The positions of the exon-intron boundaries are also conserved as evidenced from similar sizes of the exons. Evidence for some homology was also seen in intron 1, which showed maximum 84 per cent similarity with giraffe. In contrast, intron 2, 3 and 4 showed no significant similarity both in length and in sequence with other animal species. The Indian elephant GH gene has an open reading frame of 648 nucleotides encoding a signal peptide of 26 amino acid residues and a mature protein of 190 amino acid residues with both NH2- and COOH- terminal phenylalanine. Alignment of this sequence with African elephant counterpart showed that 189 amino acid residues are identical with only one variant while, with pig sequence it showed 186 identical residues with four variants. The predicted secondary structure showed that the larger α-helical lobe is formed by four sections of the polypeptide chain (residues 3-34, 47-80, 110-126 and 148-172) while the smaller lobe, which encompasses a small antiparallel beta-sheet and a small irregular structure formed the remaining structure of the polypeptide chain. The predicted tertiary structure of the Indian elephant GH showed high homology with the human GH structures. Overall, the structures of Indian elephant GH gene was found to be very similar to that of African elephant and porcine reflecting their high degree of amino acid sequence identity (99 – 97 per cent).ThesisItem Open Access Polymorphism of ovine fecundity gene linked microsatellite markers in malabari goats(Department of Animal Breeding and Genetics, College of Veterinary and Animal Sciences, Mannuthy, 2006) Seena, T X; KAU; Raghavan, K CThe objective of the present study was to explore the polymorphism of ovine fecundity gene linked microsatellite markers in Malabari goats. Malabari goats are one of the most prolific breeds in India. The microsatellite markers OarAE101, BMS2508 and BM1329 linked to the Booroola gene (FecB) and the microsatellite markers TGLA54 and TGLA68 linked to Inverdale (FecX1) gene in sheep were selected for the study. The DNA samples from 120 Malabari goats which had given birth to singles, twins, triplets and quadruplets in the second and subsequent parities were utilized for the study. DNA was isolated by phenol chloroform extraction procedure with some modifications. The DNA samples were amplified by PCR using the radioactively labeled microsatellite primers. The amplified products were resolved by polyacrylamide gel electrophoresis followed by autoradiography. The genotypes of animals were determined for each microsatellite loci by comparing the sizes of alleles with M13 phage DNA sequencing ladder. The microsatellite markers OarAE101, BMS2508 and TGLA54 were found to be monomorphic in the population under study. The microsatellite markers BM1329 and TGLA68 were found to be highly polymorphic in Malabari goats. A total of 15 alleles with 167-195 bp for the locus BM1329 and 8 alleles with a size range of 98-114 bp were observed for the locus TGLA68. The total number of genotypes observed was 34 for BM1329 locus and 12 for TGLA68 locus. Heterozygosity of 0.8660 for the locus BM1329 and 0.8024 for the locus TGLA68 were observed. The polymorphic information content (PIC) computed was 0.8526 and 0.7823 for the loci BM1329 and TGLA68 respectively. A significant difference in the alleles 181bp and 191 bp (P≤0.01) and the alleles 179 bp and 185 bp (P≤0.05) and the genotype 177/191 (P≤0.01) for the locus BM1329 were found in different types of births. The genotype 175/185 of the microsatellite marker BM1329 was found to be significantly related to a higher litter size when compared to the mean litter size of the population in Malabari goats (P≤0.01). The allele 104 bp of the locus TGLA68 was found to be significantly different in different types of births (P≤0.01). The highest frequency (0.4545) was observed in triplets followed by twins (0.2177) and singles (0.1847). The genotype 104/106 was found to be significantly different in different types of birth with triplets having a frequency of (0.4545), followed by singles (0.1087) and twins (0.0333). The season of birth had no significant effect on the type of birth and number of kidding in Malabari goats. Identification and selection of individuals that carry the alleles and genotypes associated with high prolificacy is possible in Malabari goats based on the above result. So new breeding strategies involving selection for high prolificacy can maximize the net profit of farmers. This study has brought to light important information improving the reproductive performance of Malabari goats by marker assisted selection.ThesisItem Open Access Evaluation of lactation milk yield and polymorphism of alpha-lactalabumin gene in crossbred cattle of kerala(Department of Animal Breeding and Genetics, College of Veterinary and Animal Sciences, Mannuthy, 2007) Reshmi, R Chandran; KAU; Stephen, MathewThe present study was carried out to assess the milk yield of crossbred cattle of Kerala by studying four different zones of the state viz. northern, southern, central and highlands and to analyse the association of α-lactalbumin gene polymorphism with milk production of crossbred cattle in Kerala. One day milk yield of 500 animals from each zone, at a lactation stage of 7-13 fortnights after calving was recorded. From this one-day milk yield 305-day milk yield of crossbred cattle was predicted using the formulae given by Iype (1991). The predicted lactation milk yield was used for estimating average milk yield of crossbred cattle in Kerala. The overall least squares mean of 305-day milk yield was 2351 ± 28.9 kg. Least squares analysis of variance has shown that different zones and parity exerted significant effect on 305-day milk yield (P ≤ 0.05). The highest least squares means for 305-day milk yield was in southern zone and the lowest was in central zone. The least squares mean for 305-day milk yield according to parity was highest in second parity, followed by third parity and the lowest was in fifth parity. Genomic DNA samples isolated from 25 crossbred cows selected at random from each zone was subjected for PCR-RFLP of α-lactalbumin gene at two different specific loci. On successful amplification the expected 166 bp and 429 bp fragments were obtained. Digestion of 166 bp amplified product with Mnl1 enzyme revealed similar pattern of digestion for all animals studied, indicating the absence of α-LA/Mnl1 (+) in the population. Restriction of 429 bp amplified product with Bsp12861 enzyme revealed two digestion patterns (indicating the presence of two α-LA/Bsp12861 alleles). The gene frequencies of α-LA/Bsp12861 (+) and (-) alleles were 0.08 and 0.92 respectively. In the crossbred population studied, none of the animal showed α-LA/Bsp12861 (+/+) genotype. The average milk yield of 79 α-LA/Bsp12861 (+/+) genotypes was 2779 kg and that of 16 α-LA/Bsp12861 (+/+) genotypes was only 2364 kg. However, the difference was statistically non-significant. It is suggested to conduct further research in large samples to confirm the findings and to identify other polymorphic loci associated with milk yield.ThesisItem Open Access Evaluation and comparison of polymorphism of beta casein gene in vechur and crossbred cattle of Kerala(Department of Animal Breeding, Genetics and Biostatistics, College of Veterinary and Animal Sciences, Mannuthy, 2010) Muhammed, E M; KAU; Stephen MathewBeta casein (β-CN) is the major milk protein which imparts biological, technological and physical properties to the milk. Recently, the polymorphism of the gene at codon 67 has attracted much public health attention. A single nucleotide polymorphism (SNP) from CCT to CAT leads to an amino acid change in the mature protein from proline to histidine. Among the twelve β-CN variants identified A1 and A2 are the common types and others are very rare. A1 variant has histidine at position 67 of the amino acid sequence while A2 possess proline at this position. This single amino acid change causes the release of bioactive peptides upon gastro intestinal digestion. Morphine like opioid beta casomorphine-7 (BCM-7) thus released from A1 milk is reported to cause various illness like diabetes mellitus, heart diseases, atherosclerosis, schizophrenia and sudden infant death syndrome (SIDS). The original variant A2 does not produce BCM-7 and thus is safe for human consumption. The major taurine milch breeds such as Holstein Friesian and Ayrshire have a high frequency of A1 allele where as Channel Island breeds such as Guernsey and Jersey have more of A2 allele. It is also interesting to note that most of the Indian breeds of animals have only β-CN A2 allele. The present study was undertaken to characterise the β-CN gene polymorphism in Vechur and crossbred cattle of Kerala considering its public health importance. Blood samples were collected from 72 Vechur cattle, and 14 Kasargode Dwarf cattle available in the KAU farm and 100 crossbred cattle randomly selected from different parts of Kerala. Genomic DNA was isolated by standard phenol chloroform procedure. Beta casein A1 A2 polymorphism was analysed by Allele Specific Polymerase Chain Reaction (AS-PCR). The genotypic frequencies of A1A1, A1A2 and A2A2 were, respectively, 0, 0.40 and 0.60 in Vechur cattle, 0.32, 0.28 and 0.40 in crossbred cattle and 0, 0.79 and 0.21 in Kasargode cattle. Genotypic frequencies were not found to be in Hardy-Weinberg equilibrium in crossbred cattle while in Vechur and Kasargode cattle frequencies were found to be in equilibrium. The A1 and A2 allele frequency was 0.20 and 0.80 in Vechur cattle, 0.46 and 0.54 in crossbred cattle and 0.39 and 0.61 in Kasargode cattle. Comparison of allele frequencies revealed that there is significant variation in allele frequencies among these three groups of animals. The relationship between β-CN A1/A2 polymorphism with milk yield was also assessed. The average daily milk yield was 1.27±0.05 kg in Vechur cattle. The peak yield of crossbred cattle was 10.71±1.046 kg. The average daily milk yield for A1A2 genotype in Vechur cattle was 1.52±0.08 kg and 1.14±0.04 kg for A1A2 genotype. The t-test showed the difference in the milk yield of the two genotypes was significantly different at 5% level of significance. In crossbred cattle the peak yield (kg) of A1A1 genotype was 14.64±3.181, 8.54±0.194 for A1A2 genotype and 9.09±0.125 for A2A2 genotype. The A1A1 genotype in crossbred cattle showed significantly higher average peak yield compared to other genotypes and difference between A1A2 and A2A2 genotypes were not significantly different. From the present study it can be concluded that selection for enhancing milk production may increase the frequency of harmful A1 allele in our bovine population. So efforts should be taken to enhance the A2 allele with a view of transforming our cattle population capable of producing A2 variant of β-CN which has a global demand. The information generated in this study on the genotypes of Vechur and Kasargode dwarf cattle can be very effectively used for developing a herd/breed of cattle with A2A2 β-CN genotype.