PHENOTYPIC AND GENETIC CHARACTERIZATION OF INDIGENOUS PIGS OF MEGHALAYA (NIANG MEGHA) AND ASSAM (DOOM)
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Date
2013-07
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Assam Agricultural University, Khanapara, Guwahati
Abstract
Characterization of indigenous livestock population is of utmost importance for their conservation and genetic improvement for sustainable utilization in future. The present study was carried out on phenotypic and genetic characterization of indigenous pigs of Meghalaya (Niang Megha) and Assam (Doom). A total of 99 farrowing records of Niang Megha pigs maintained at the Livestock Farm, Livestock Production Division, ICAR Research Complex for NEH Region, Umiam, Meghalaya and 40 farrowing records of Doom pigs maintained under the GOI sponsored project on “Conservation of Doom pig”, Livestock Research Station, AAU, Mandira, Kamrup, Assam were utilized for the present investigation. Genetic characterization of indigenous pigs of Meghalaya and Assam was carried out utilizing 14 microsatellite markers.
The averages for litter size at birth, litter size at weaning, litter weight at birth, litter weight at weaning, age at first estrus, age at first fertile service, age at first farrowing, farrowing interval and gestation period were 6.080 ± 0.219, 5.202 ± 0.190,
3.172 ± 0.107 kg, 30.614 ± 1.199 kg, 221.173 ± 1.527 days, 246.440 ± 1.385 days, 347.813 ± 3.516 days, 206.121 ± 0.785 days and 111.848 ± 0.136 days respectively in Niang Megha and 6.250 ± 0.237, 5.025 ± 0.210, 3.475 ± 0.114 kg, 30.289 ± 1.184 kg, 225.600 ± 1.494 days, 250.567 ± 1.481 days, 368.000 ± 1.537 days, 213.533 ± 0.396 days and 112.044 ± 0.295 days respectively in Doom pigs. The averages for body weight at birth, weaning, 3 months, 6 months, 8 months and 12 months of age were found to be 0.520 ± 0.003 kg, 5.967 ± 0.039 kg, 10.299 ± 0.056 kg, 21.585 ± 1.263 kg,
30.633 ± 0.163 kg and 39.350 ± 0.178 kg respectively in Niang Megha and
0.556 ± 0.003 kg, 5.944 ± 0.412 kg, 10.738 ± 0.087 kg, 24.241 ± 0.251 kg,
42.925 ± 0.852 kg and 49.879 ± 0.911 kg respectively in Doom pigs. The average body length, height at wither, heart girth and neck girth respectively at birth, at weaning and at adult age in Niang Megha was recorded as 17.256 ± 0.062 cm, 11.293 ± 0.053 cm,
18.107 ± 0.050 cm, 14.450 ± 0.077 cm; 34.498 ± 0.116 cm, 23.969 ± 0.103 cm,
33.127 ± 0.080 cm, 28.124 ± 0.049 cm and 58.505 ± 0.341 cm, 45.636 ± 0.423 cm,
62.150 ± 0.268 cm, 52.411 ± 0.323 cm and in Doom pigs as 17.620 ± 0.070 cm,
12.224 ± 0.064 cm, 21.705 ± 0.152 cm, 15.175 ± 0.092 cm; 35.318 ± 0.067 cm,
25.767 ± 0.108 cm, 35.982 ± 0.170 cm, 31.542 ± 0.182 cm and 74.647 ± 0.561 cm,
58.115 ± 0.329 cm, 78.322 ± 0.654 cm and 64.705 ± 0.345 cm. The coat colour pattern of Niang Megha pig revealed that 26.582 per cent animals were solid black and 73.418 per cent were black with white patches on forehead and legs. The coat colour of Doom pig was observed to be black in all the animals studied.
Significantly (P<0.05) lower averages were found in Niang Megha pigs as compared to Doom pigs in respect of age at first estrus, age at first fertile service, age at first farrowing and farrowing interval. The body weights of Doom pigs at all the ages except at weaning were found to be significantly (P<0.05) higher compared to Niang Megha. The conformation traits studied viz. body length, height at wither, heart girth and neck girth were significantly (P<0.05) higher in Doom pigs as compared to Niang Megha at birth, weaning and at adult age.
A total of 14 microsatellite markers recommended by FAO/ISAG were employed to understand the genetic characteristics and the genetic relationships of the two pig populations. The results indicated that all the loci were polymorphic and highly informative. The observed number of alleles ranged from 5 (SW911) to 9 (S0026) in Niang Megha and from 7 (S0155, S0002 and SW911) to 11 (S0005) in Doom pigs with a total of 143 alleles in the two populations studied. The average number of alleles per locus was 6.857 ± 0.294 in Niang Megha and 8.571 ± 0.343 in Doom pigs with an average value of 7.714 ± 0.276. The average effective number of alleles was 4.504 ± 0.266 in Niang Megha and 5.316 ± 0.228 in Doom pigs. The Shannon information index was 1.757 ± 0.038, indicating high genetic diversity. The observed and expected heterozygosity were
0.667 ± 0.043 and 0.767 ± 0.015 respectively for Niang Megha pigs. The observed heterozygosity was lower in Doom pigs (0.657 ± 0.049) as compared to Niang Megha. The polymorphic information content (PIC) was found to be 0.734 ± 0.017 in Niang Megha and
0.785 ± 0.010 in Doom pigs. Genetic difference between the two populations was low with an average FST value of 0.050, which showed that the average proportion of genetic variation explained by population differences was 5 %. The FIS ranged between
-0.132 (S0026) and 0.492 (S0225) in Niang Megha with an average of 0.132 ± 0.052 and between -0.117 (S0101) and 0.669 (SW911) in Doom pigs with an average of
0.188 ± 0.058. When the agreement with Hardy-Weinberg equilibrium (HWE) was tested, 9 and 7 out of 14 loci showed significant deviations from HWE in Niang Megha and Doom pigs respectively. Deviations from HWE are linked to a high positive FIS value.
Non significant heterozygote excess on the basis of infinite allele model (IAM), two phase model of mutation (TPM) and stepwise mutation model (SMM) as revealed by sign test, standardized differences and Wilcoxon sign rank tests, along with a normal L - shaped distribution of mode shift test indicated no recent bottleneck in both the populations. Genetic distance between the two pig populations was 0.424, which showed that the two populations are distinct from each other. The microsatellite markers used in the present investigation proved to be useful for genetic characterization studies of the pig populations and the present study contributed to the knowledge on phenotypic and genetic characterization of the pig populations of North East India.
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