POLYMORPHISM OF INTRON 2 OF GROWTH HORMONE GENE AND ITS ASSOCIATION WITH GROWTH AND CARCASS TRAITS IN KUTTANAD AND WHITE PEKIN DUCKS
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Date
2022-02-10
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COLLEGE OF VETERINARY AND ANIMAL SCIENCES MANNUTHY, THRISSUR, KERALA VETERINARY AND ANIMAL SCIENCES UNIVERSITY
Abstract
A study was conducted at Avian Research Station, Thiruvazhamkunnu, Palakkad to compare the growth and carcass traits of unselected flock of Kuttanad ducks (UKD), improved meat line of Kuttanad ducks (IKD) and White Pekin ducks (WPD) and to study the association of polymorphism of intron 2 of Growth Hormone gene with economic traits. One hundred and twenty five day-old ducklings from each group were selected, wing banded and were reared in uniform management condition. Ad-libitum feed and water were provided and ducks were reared up to 10 weeks of age. Fortnightly body weight, body weight gain, feed consumption, feed conversion ratio, livability were calculated. Carcass traits like slaughter weight, carcass weight, dressing percentage (with and without giblets), yield of feathers, giblets and cut-up parts were studied at 6, 8 and 10 weeks in eight birds of each group. Blood samples of 50 birds from each group were collected and DNA was isolated. Isolated DNAs were utilised for PCR-RFLP to find out the polymorphism in intron 2 of GH gene. WPD showed significantly (p<0.05) higher body weight at all fortnights whereas body weight of two groups of Kuttanad ducks were significantly (p<0.05) similar. Body weight gain were significantly (p<0.05) high for WPD at all fortnights except during first fortnight where IKD registered significantly (p<0.05) higher body weight gain. The period of active weight gain was during seven to eight weeks in all the three groups of ducks. WPD showed lower FCR in all fortnights followed by IKD. Cumulative FCR of 4.17 and 4.68 were shown by WPD and IKD, respectively for 10 weeks of age. The fortnightly livability of ducks of all the three groups were satisfactory. It was found that slaughter weight and carcass weight were significantly (p<0.05) higher in WPD at 8 and 10 weeks of age. Dressing percentage (with and without giblets) of UKD and IKD were significantly (p<0.05) higher at eight weeks whereas WPD showed significantly (p<0.05) higher percentage at 10 weeks of age. The appearance score after defeathering showed progress in accordance with the age. The yield of back, thigh and drumstick progressively reduced as age progressed from 6 to 10 weeks in UKD, IKD and WPD, whereas that of breast increased and the yield of wings and neck was more or lesssimilar throughout the ages. The PCR- RFLP technique and sequencing methods were employed to identify the genotypes in three duck population viz. UKD, IKD and WPD. Three genotypes GH/TT, GH/CT and GH/CC and two alleles T and C were identified in all the three groups of ducks by banding patterns. Even though the genotypes and allele frequencies did not differ significantly between the three groups of ducks, the frequent genotype observed in IKD and WPD was GH/TT whereas that in UKD was GH/CT. Reported primers were used to find polymorphism in intron 2 and Cytosine/Thymine polymorphism at 170th position could be identified. Association of polymorphism of intron 2 of GH gene with body weight and carcass traits were analysed in this study, but no significant difference was observed between the genotypes and the economic traits (body weight and carcass traits). However the yield of different traits were numerically higher for genotypes GH/TT and GH/CT. From the results, it could be concluded that the meatproduction potential of Kuttanad ducks could be improved through the selection and breeding for over 4 generations. Identification of polymorphism in intron 2 of GH gene and its association with growth and carcass traits revealed that it can be used as a molecular marker in the selection of ducks at younger ages. However, further research is essential to confirm and extend these findings.