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ThesisItem Open Access Evaluation of sister chromatid exchanges in cattle reared in a radio active belt area of Southern Kerala(Department of Animal Breeding and Genetics, College of Veterinary and Animal Sciences, Mannuthy, 1999) Dinesh, C N; KAU; Raghunandanan, KA cytogenetic investigation on the effect of long-term background radiation on cattle was carried out in this study. It involved the analysis of sister chromatid exchanges (SCEs) which was the most sensitive and quickest mammalian system to find out the effect of mutagens on genetic material. The technique standardized for sister chromatid differentiation (SCD) involved culturing of lymphocytes in RPMI-1640 medium and incorporation of 5-bromo-2-deoxy uridine (BrdU) at 20th hour of incubation. The cells were harvested at the end of 70th hour and the thionine stained~slides were exposed to UV light for one hour at a distance of one foot from the UV source. analysed for SCE. Metaphase spreads showing SCD were Cattle reared in the four coastal wards of Chavara Panchayat (Kovilthottam, Cherusseribhagam, Kolangarabhagam and Kari thura) were taken as experimental group. Cattle from University Livestock Farm (ULF) , Mannuthy, which has no reports of background radiation, formed the control group. The mean SCE frequency per cell was found to be 1.536 ± 0.249 and 3.368 ± 0.273 for control and experimental groups, respectively. The range and number of SCEs/cell/generation for control animals were 0 to 5 and 0.768, respectively. In the experimental group it was 0 to 9 and 1.684. Thus an increase of 119.27 per cent in SCE frequency was recorded in high background radiation area when compared to that of control. The mean SCE frequencies for cattle of Kovilthottam, Cherusseribhagam, Kolangarabhagam and Karithura were 4 ± 0.966, 2.563 ± 0.584, 3.206 ± .411 and 3.389 ± 0.504, respectively and the SCE ranges were 0 to 7, 0 to 6, 0 to 7 and 0 to 9. There was no significant difference in SCE frequency among the four wards. The difference between SCE frequencies of Kovilthottam, Kolangarabhagam and Karithura to that of control was significant. This could be due to the effect of high background radiation on DNA and chromosomes. However, difference in SCE frequency between Cherusseribhagam and control was not significant. This could be due to non- homogenous distribution of monazite deposits in the coastal belt. Though the increase in SCE frequencies in Karithura, Kolangarabhagam and Kovilthottam were statistically significant, cattle reared in this area did not reveal any deviation in physiological and phenotypic performance. Thus this study indicates that SCE frequenc,y for cattle reared in Chavara panchayat with high background radiation was significantly higher than that of control group. This discloses the occurrence of chromosomal damage in this area though these cattle performed normally. This may be because of the repair mechanism or balanced by exchange mechanism during active replication of chromosomes.ThesisItem Open Access Immunogenetic influences on litter traits, viability and growth in broiler rabbits(Department of Animal Genetics and Breeding, College of Veterinary and Animal Sciences, Mannuthy, 1999) Marykutty, Thomas; KAU; Nanadakumar, PA detailed investigation into the genetic and environmental factors influencing litter traits, growth and viability among three temperate broiler breeds of rabbits namely New Zealand white, Grey Giant and Soviet Chinchilla, maintained at rabbit research station under the Centre for Advanced Studies in Animal Genetics and Breeding of Kerala Agricultural University was undertaken. The effect of breed and sire on litter traits, growth and viability were assessed. Association among these traits were estimated. In an attempt to ascertain the genetics of humoral immune response of broiler rabbits, antibody response to chicken RBC was analysed. The influence of breed, sex and sire on humoral immune response was ascertained. Heritability of humoral immune response was worked out. The interrelationship between humoral immune response, growth and viability was estimated. Litter size at birth averaged 4.37 ±0.15 among rabbits. The effect of breed and sires within breed was not significant on this trait. Grey Giant rabbits had highest litter size at birth. Overall mean for litter weight at birth was 227.36 ± 6.81 g. Breed and sire effects were not significant on litter weight at birth. Grey Giant breed had highest litter weight at birth of 236.70 ± 14.74 g. Breed differences were significant (P:5 0.05) for the litter size at weaning among broiler rabbits. Grey Giant had largest weaning litter size of 1.96±0.25 followed by New Zealand White (1.87 ±0.24) and Soviet Chinchilla (1.18 ± 0.21). The effect of sires on this trait was not significant. The effect of breed on litter weight at weaning was significant (P:5 0.05). Grey giant had heaviest litter weight at weaning with a mean of 1084.15 g New Zealand White and Grey Giant had weaning litter weight of 1073.88 g and 707.96 g respectively. Sire component of variance was not significant for this trait. Pre-weaning mortality among the three breeds of broiler rabbits averaged 76.20%. The influence of breed on preweaning mortality was significant (P :50.05). New Zealand White rabbits had least preweaning mortality and Grey Giant suffered from maximum preweaning losses. Preweaning mortality among the litters of various sire groups were not differed significantly. Phenotypic correlation coefficient among litter size traits and litter weight traits studied were positive and highly significant (p:5 0.01). Litter size traits had highly significant (P:5 0.01) positive correlation with litter weight traits. Pre-weaning mortality had a highly significant (P:50.01) negative correlations of (-)0.27, (-)0.85 and (-)0.81 respectively with litter weights at birth and at weaning and litter size at weaning. Association between litter size at birth and preweaning mortality was significant (P:5 0.05) and negative. Genetic correlations of litter size at birth with litter weight at birth and litter weight at weaning were highly significant (P:=:; 0.01) and positive. Litter weight at birth had a highly significant (P:=:; 0.01) genetic correlation with litter size at weaning. Overall mean of body weight at weaning was 611.73 g among rabbits. Effect of breed and sire was not significant on this trait. Grey Giant, New Zealand White and Soviet Chinchilla respectively had weaning weight in grams of 641.92, 614.33 and 564.36. Body weight at 12 week averaged 1168.41 g in broiler rabbits. Though the breed effect was not significant, Soviet Chinchilla had heaviest body weight at 12 week with a mean of 1237.66 g followed by New Zealand White (1132.97 g) and Grey Giant (1121.19 g). The effect of sire was significant(p :=:;0.05) for the variation body weight at 12 week. Effect of breed, sire and sex on Forssman antibody titre to chicken RBC was not significant. Forssman antibody titre (1 + loge) averaged 0.11 in the population. Antibody response to chicken RBC peaked 7 day post immunisation with a mean of 4.208 and dwindled to a mean of 3.454 and 2.932 respectively on 14 and 21 day post immunisation. The effect of breed was not significant on 7 and 14 day post- immunisation antibody titres to chicken RBC. However, 21 day post- immunisation antibody titres to chicken RBC was significantly (P::; 0.05) influenced by the breed. Soviet chinchilla rabbits consistently had higher antibody titres with a mean of 4.3715,3.6320 and 3.2903 at 7, 14 and 21 day post-immunisation. Though not significant, males had higher antibody titres to chicken RBC compared to females. sire had significant effect on 7th day (P = 0.0486), 14th day (P = 0.0218) and 21 st day (P = 0.0047) post- immunisation antibody titres. Heritability estimates were high for the immune response traits. Phenotypic correlation between 7, 14 and 21 day postimmunisation antibody titres were highly significant (P::; 0.01). Association of Forssman antibody titre with postimmunisation antibody titres were not significant. Body weight at weaning had significant (P::; 0.05) negative correlation of (-)0.18 and (-)0.19 respectively, with 14 and 21 day postimmunisation antibody levels to chicken RBC.