Putative SNPs in Ovar-DRB1 and GALNTL6 Genes Conferring Susceptibility to Natural Infection of Haemonchus Contortus in Southern Indian Sheep.

AIM: To explore associations between phenotypic traits and polymorphisms in the DRB1 and GALNT6 gene in Nellore, Deccani and Kenguri sheep naturally infected with Haemonchus contortus. MATERIALS AND METHODS: Blood and faecal samples were collected to evaluate fecal worm egg counts (FEC), packed cell volume (PCV), hemoglobin (Hb), eosinophilia and for DNA isolation. RESULTS: Animals were grouped into susceptible and resistant groups based on EPG counts. FEC and circulating eosinophilia were higher in a susceptible group. Log FEC was negatively correlated (P < 0.01) with PCV, and Hb estimates. The second exon of DRB1 and intron variant of GALNTL6 genes were amplified from DNA samples of resistant and susceptible sheep. Characterization of Ovar-DRB1 amplicon by RFLP revealed two genotypes ('bb' and 'ab'). The genotype frequencies differed significantly between both groups (P < 0.05). The 'bb' genotypes had higher (P < 0.05) log FEC value than 'ab' genotypes and 'b' allele was linked with susceptibility to haemonchosis in sheep. The mean FEC of Nellore sheep was high indicating susceptibility of the breed and also in which the frequency of 'b' allele was more compared to the other two breeds. OVAR-DRB1 genotypes associated with FEC did not affect PCV and Hb. PCR-RFLP assay developed to determine the genotypes with respect to SNP rs424521894 of GALNTL6 revealed monomorphic nature at the locus in the breeds studied. CONCLUSION: MHC polymorphism could be used as a genetic marker for the selection of sheep resistant to H. contortus. However, a more intensive study, involving controlled infections and other GALNTL6 SNPs may be enforced to make any decisive assertion.

Assessment of Mutation Drift Equilibrium and the Occurrence of a Recent Genetic Bottleneck in South Indian Zebu Cattle.

During the last few decades, the effective population size of indigenous zebu cattle breeds has declined drastically, resulting in the classification of some of them into the vulnerable, endangered, or critically endangered category. Drastic reductions in the effective size of a population may result in genetic bottlenecks and can affect within-breed genetic variability and its viability. The present study was undertaken with the objective of evaluating South Indian zebu cattle populations for mutation drift equilibrium and to detect the occurrence of recent genetic bottleneck events. A total of 293 cattle from eight indigenous breeds were genotyped at 27 FAO/ISAG-recommended microsatellite marker loci. Three different statistical tests, viz., the sign test, standardized differences test, and Wilcoxon sign rank test were performed using allele frequency data to detect loci with heterozygosity excess under the infinite alleles, stepwise, and two-phase mutation models. Under the infinite alleles model, the observed number of loci with heterozygosity excess (He > Heq) ranged between 10 and 19 among the investigated cattle breeds. However, the observed heterozygosity excess was not statistically significant (p > 0.05) in any of the studied breeds. Similarly, the standardized differences test and Wilcoxon sign rank test revealed no concrete evidence for the occurrence of a recent genetic bottleneck in South Indian zebu cattle breeds. The qualitative test for mode-shift distortion revealed a normal L-shaped distribution of allele frequencies, suggesting a lack of evidence for the loss of low-frequency alleles in all the investigated South Indian zebu cattle breeds.

Cypermethrin and ivermectin resistance in field populations of Rhipicephalus sanguineus sensu lato (Latrielle, 1806) collected from dogs in south India.

The abuse of acaricides for control of Rhipicephalus sanguineus sensu lato ticks led to a strong selection pressure for acaricide resistance. Data on acaricide resistance in R. sanguineus s.l. populations from India is meager though veterinarians frequently report treatment failures. The present study was aimed to characterize the level of resistance in R. sanguineus s.l. against most commonly used drugs, cypermethrin and ivermectin in Andhra Pradesh, south India. Fourteen adult female tick populations were collected from naturally infested dogs at veterinary clinics, residence and stray dog in nine state municipal corporations/municipalities. Information on the history of dog treatment with acaricides was obtained by interviewing dog owners. The larval packet test (LPT) and larval immersion test (LIT) were used on the larvae of ticks to test for resistance to cypermethrin and ivermectin, respectively. Mortality data of each tick population was analyzed by probit analysis. Corresponding to the most susceptible population, thirteen (92.6%) and six (42.9%) tick populations were regarded as resistant to cypermethrin and ivermectin, respectively. The phenotypic level of cypermethrin (resistance ratios at LC50% varied from 1.55 to 13.29) and ivermectin (resistance ratios at LC50% ranged from 1.16 to 4.79) resistance varied distinctly between the populations. Additionally, all the populations were tested using PCR to demonstrate the frequency of the point mutation in sodium channel gene that corresponds with resistance of R. sanguineus s.l. to cypermethrin. A nucleotide substitution (T2134C) on domain III segment VI of the sodium channel gene was noticed in phenotypically resistant tick populations on DNA sequencing. Ivermectin resistance in the brown dog ticks is reported for the first time from India.

Single nucleotide polymorphism in STAT5A could not endorse variation in milk production traits in Indian bovine population.

The Signal Transducer and Activator of Transcription 5A (STAT5A) gene involved in activating the transcription of milk protein genes was predicted to be influencing milk production traits. The present study was undertaken to investigate the suitability of the polymorphism of STAT5A as a marker for milk traits in Ongole, crossbred cattle and Murrah buffaloes from Southern India. Blood samples (n = 502) for DNA isolation and milk samples (n = 222) from different genetic groups were collected from various farms. The gene variants upon polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) on the exon 7 region of STAT5A were subjected to GLM analysis to evaluate their association with milk production traits. The frequencies of C and T alleles at the STAT5A/AvaI locus were 0.98 and 0.02 (Jersey crossbred), 0.94 and 0.06 [Holstein-Friesian (HF) crossbred], 0.97 and 0.03 (Ongole). T allele was not observed in Murrah buffaloes. The least squares mean lactation milk yield of CC and CT genotypes of STAT5A were 2,096.90 ± 48.63 and 2,294.41 ± 215.85 kg in Jersey crossbred, 2,312.92 ± 91.01 and 2,392.82 ± 207.66 kg in HF crossbred and 528.40 ± 22.10 and 396.37 ± 76.17 kg in Ongole cattle, respectively. The milk fat content of the CC genotype was higher (P > 0.05) in Jersey crossbred cattle. The CT genotypes of Ongole and HF crossbred cattle recorded a higher fat per cent than the CC genotypes. Significant associations were not observed in support of STAT5A as a marker for milk production traits in either Ongole or crossbred cattle of indicine admixture and no reason could be found to consider this locus as universal markers for milk production traits in indicine cattle and buffaloes. Considering the monomorphic nature of the gene in buffaloes and their higher milk fat content as compared to bovine milk, much remains to be explored regarding the underlying differences across the bovine and the bubaline species.

Evaluation of non-synonym mutation in DGAT1 K232A as a marker for milk production traits in Ongole cattle and Murrah buffalo from Southern India.

Various candidate genes have been reported to affect milk yield and composition in dairy cattle. A non-synonymous mutation in the DGAT1 gene, i.e., K232A was reported to have a strong association with milk yield and milk composition of Bos taurus. A study has been undertaken on 502 unrelated individuals belonging to indigenous Ongole cattle, crossbred cattle, and Murrah buffaloes from the Indian sub-continent with the objective to determine the polymorphism of the K232A locus and their association with milk yield and composition. Typing DGAT1 K232A allelic variation by PCR-RFLP using CfrI restriction enzyme revealed three genotypes in crossbred cattle. Genotype KK was more prevalent (0.60) in Jersey crossbred, whereas in Holstein Friesian crossbred it was KA genotype (0.48). In Ongole cattle and Murrah buffaloes, the locus did not exhibit polymorphism. The least-square mean of milk yields pooled over lactations across the DGAT1 variants was significantly (P < 0.05) higher among the homozygous (AA) genotypes, both in Jersey crossbred and HF crossbred cattle after adjusting for the effects of farm, parity, and season. The fat, SNF, and protein content values of AA genotypes were less than the KK genotypes in both the genetic groups (P > 0.05). The fixation of the DGAT1K allele at the locus in Bos indicus cattle and Bubalus bubalis in the present study did not support its use as a reliable universal marker for milk production and composition traits.

In Vitro Anthelmintic Activity of Three Tropical Plant Extracts on Haemonchus contortus.

AIM: To evaluate the anthelmintic activity of Anacardium occidentale shell, Illicium verum fruit, and Artocarpus heterophyllus seed to substantiate their traditional use against helminths. MATERIALS AND METHODS: In vitro anthelmintic activity of hydroalcoholic extracts of three plants was evaluated against eggs, infective larvae (L3), adult, and lactate dehydrogenase (LDH) of Haemonchus contortus of naturally infected sheep. RESULTS: The three extracts exhibited significant (P < 0.001) dose-dependent anthelmintic responses by inhibiting egg hatching and causing paralysis of larvae and mortality of worms. The extracts were most effective on egg and adult stage of H. contortus than on L3 stage at a higher concentration of 6 mg/mL. Anacardium occidentale shell exhibited maximum activity with 100% paralysis of L3 larvae. Probit analysis revealed that the extracts of A. Occidentale shell induced 50% egg hatch inhibition (LD50 = 0.0255 mg/mL), larval paralysis (LD50 = 0.196 mg/mL), and adult worm mortality (LD50 = 1.0365 mg/mL) at a lower concentration (LD50) compared with those of I. verum fruit and A. heterophyllus seed extracts. Further, all extracts significantly (P < 0.01) inhibited the LDH activity catalyzing the oxidation of lactate in adult H. contortus, with maximum level of inhibition caused by A. occidentale shell extract. CONCLUSION: Phytochemical screening of the extracts revealed the presence of alkaloids, flavonoids, tannins, saponins, and amino acids that could be responsible for the anthelmintic effects noticed. The results warrant further in vivo evaluation of these plants for potential use as anthelmintic agents.

Studies on prevalence and histomorphology of Sarcocystis species infecting cattle in Andhra Pradesh, India.

The present study was carried out to determine the prevalence of bovine sarcocystosis and identify the different species of Sarcocystis cysts in cattle in different regions of Chittoor district, Andhra Pradesh. A total of 150 slaughtered cattle over a period of 1 year were examined both macroscopically and microscopically for the presence of Sarcocystis infection. Out of 150 slaughtered cattle examined, macroscopic sarcocysts were observed in nine cattle and were exclusively found in oesophagus. Examination of tissue samples collected from different predilection sites from each of 150 cattle by pepsin-HCl digestion method revealed presence of live banana shaped bradyzoites under light microscopy in 134 cattle. Six cattle that were positive by macroscopic examination were also positive by microscopic examination of tissues. The overall prevalence of Sarcocystis infection in cattle of Chittoor district was 91.33%. The prevalence of macroscopic and microscopic sarcocysts was 6.57 and 93.43% respectively. Statistically a significant relationship between the prevalence of infection among different age groups (P < 0.001) and no significant relationship (P > 0.001) between the prevalence of Sarcocystis infection in male (91.76%) and female (90.76%) cattle was observed. In both male and females the prevalence of Sarcocystis infection increased with age. Microscopically sections of tissues from cattle that were positive by tissue digestion technique revealed thin walled cysts (4.5 ± 0.5 µm) in 131 samples and thick walled cysts (0.5 ± 0.12 µm) in six cattle.