GENETIC EVALUATION OF ONGOLE CATTLE UNDER PROGENY TESTING PROGRAMME
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Date
2010-05
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SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA
Abstract
ABSTRACT :
The data on Ongole cattle maintained under the ICAR Network Project on Genetic improvement of Ongole breed through the Associate Herd Testing Programme at Lam farm, Guntur (1935), Cattle Breeding Farm, Chadalawada, Prakasam district (625), Livestock Research Station Mahanandi, Kurnool district (404) and Composite Livestock Farm, Chintaladevi, Nellore district (201), spread over a period of 22 years from 1987 to 2008, were analyzed. Multivariate analysis was undertaken to estimate the genetic divergence between the sets of the bulls under the progeny testing programme. The morphometric differences of the chromosomes between the cows born by embryo transfer technique and artificial insemination were studied. The overall least squares means for body weight, height at withers, chest girth and body length of Ongole cattle from birth to 24 months of age ranged from 26.49 to 245.40 kg, 71.58 to 133.58 cm, 66.35 to 146.53 cm and 62.91 to 127.64 cm, respectively. The effects of farm and period of birth were significant on the body weight, height at withers, chest girth and body length at all the ages studied. Season of birth significantly affected the body weight at birth, 1 and 3 months of age; height at withers at birth, 1 and 6 months age; chest girth at 3 months and body length at 6 months of age. The sex of the calf and set of the bulls significantly influenced the body weights and biometrical measurements, virtually at all the ages.
The overall least squares means for 300-days lactation milk yield, total lactation milk yield, lactation length, peak yield, days to reach peak yield, milk yield per day of lactation and milk yield per day of calving interval were 718.53 kg, 720.90 kg, 233.99 days, 3.90 kg, 35.67 days, 3.08 kg and 1.43 kg, respectively and almost all these traits were affected significantly by the farm, period of calving, set of the bulls and order of lactation. However, peak yield alone was affected (P<0.01) by the season of calving and none of the production traits were influenced by the sex of the calf. The overall least squares means of number of inseminations per conception, age at first conception, age at first calving, gestation period, service period, dry period and calving interval were 2.02, 1358.82 days, 1592.22 days, 287.58 days 232.38 days, 282.94 days and 517.61 days, respectively and almost all these characters were affected by the farm, period, set of the bulls and order of lactation, while none of the reproductive traits were influenced by the season. Sex of the calf had significant influence on gestation period and dry period only. The mean breeding efficiency of the Ongole cows varied from 63.66 to 83.75 per cent and the rank correlations of breeding efficiency estimated by three different formulae were positive and significant. The farm and set of the bulls significantly influenced the breeding efficiency.
The overall least squares means for life time milk yield, herd life, productive life, milk yield per day of herd life and productive life; wet days and dry days per herd life; wet days and dry days per productive life and gestation period per herd life and productive life were 3805.88 kg, 3773.84 days, 2287.48 days, 1.00 and 1.67 kg; 32.15 and 67.85%; 53.58 and 46.41% and 39.46 and 66.54%, respectively and all these traits were influenced by one or the other of the non-genetic effects studied. However, none of these characters were influenced by the set of the bulls.
The estimates of heritability and genetic and phenotypic correlations of body weights and biometrical measurements varied from 0.01 to 0.43, 0.06 to 0.99 and 0.03 0.40 respectively. Similarly, the heritabilities of 300-days lactation milk yield, total lactation milk yield, Lactation length, peak yield, milk yield per day of lactation, milk yield per day of calving interval, gestation period, service period, dry period and calving interval were 0.27, 0.24, 0.21, 0.24, 0.09, 0.22, 0.14, 0.06, 0.06 and 0.06, respectively. The genetic correlations among production and reproduction traits were positive and ranged from 0.04 to 0.99, while the phenotypic correlations among these traits varied from 0.01 to 0.49. The heritability estimates for life time milk yield, herd life, productive life, lactation milk yield per herd life and productive life; wet and dry days per herd life; wet and dry days per productive life and gestation period per herd life and productive life were 0.66, 0.10, 0.17, 0.49 and 0.49; 0.23 and 0.23; 0.30 and 0.30 and 0.08 and 0.08, respectively. The genetic correlations among the various life time production traits ranged between 0.69 and 0.99 whereas the phenotypic correlations ranged from 0.01 to 0.47. The Mahalonobis genetic distances (D2) between all combinations of sets were highly significant. The calving interval, total lactation milk yield and lactation length contributed 40%, 40% and 20% to the total genetic diversity among the sets. Two distinct clusters were formed, the first one consisting of sets 1, 2, 3 and 5, while the second cluster had only 4th set. The diploid chromosome number was found to be 60, XX in both ET born and AI born cows. All autosomes were acrocentric, while the X-chromosome was longest submetacentric. The mean relative length of the autosomes varied from 1.95 to 4.97 and 1.95 to 4.99 per cent in ET and AI born cows respectively. The relative length of chromosome 20 of ET born cows was significantly longer (2.86%) than that of the AI born cows (2.77%). Except this, no other differences either in chromosome number or in chromosome morphology were detected between the ET born and AI born cows, suggesting that ET born cows were as good as the AI born cows with respect to their chromosome profiles. The present study indicated that the overall performance of the animals of Lam farm, with respect to the production, reproduction and life time traits, was the best, followed by Chadalawada, Mahanandi and Chintaladevi farms. The performance of the Ongole cattle during various periods did not exhibit any specific trend while the animals either born or calved during summer exhibited superior performance, when compared to those in rainy and winter seasons. The production and reproduction performance of the cows delivering female calves was better than those giving birth to male calves. The genetic variation among the set of bulls did not show a definite trend although the multivariate analysis revealed two clusters, one consisting of sets 1, 2, 3 and 5 and another set 4, with a considerable inter cluster distance.
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