Aseel, a popular breed of native chicken, characterized by its pugnacity, fighting strength and royal gait is being used to create crosses for domestic chicken production. However, information on its growth models is scanty. An experiment was conducted to evaluate different non-linear models and to find out best fitting model in Aseel, being maintained at Central Avian Research Institute, Izatnagar, Bareilly. Data on body weights from 12-weeks of age to 20-weeks of age at biweekly intervals were recorded on a random bred single-hatched flock. Owing to the non-linear characteristic of growth, three non-linear models namely, Gompertz, Bertalanffy and Logistic models were evaluated. Goodness of fit for all the models were checked using coefficient of determination (R2), adjusted coefficient of determination (Adj-R2), mean square error (MSE), mean absolute error (MAE) and Akaike information criterion (AIC). The Bertalanffy model most accurately characterized the growth trend in males, females and pooled sex data. The study revealed that this model may be used to ascertain the average body weights in Aseel chicken under random mating. The investigation has generated baseline data on growth modelling of random bred groups and may be used in similar investigations on other native chicken breeds.
The present research was aimed to perform genetic analysis of first lactation monthly test day milk yields, first lactation 305 days and lifetime milk yield of Sahiwal cattle. Data were collected on 867 Sahiwal cows sired by 76 bulls over a period of 31 years. Complete genetic analysis of all the traits was done using Harvey (model 2). The heritability of MTDMY ranged from 0.12 ± 0.06 (TD10) to 0.48 ± 0.09 (TD4) by LSML. The heritability estimates for FL305DMY and LTMY were found to be 0.40 ± 0.09 and 0.34 ± 0.07 respectively. The estimates of phenotypic and genetic correlation among all the monthly test day milk yields ranged from 0.14 to 0.79 and 0.15 to 0.99 respectively. The genetic correlation of MTDMY and FL305DMY ranged from 0.66 (TD1) to 0.99 (TD7, TD10).The phenotypic correlation of MTDMY with FL305DMY ranged from 0.29±0.04 (TD1) to 0.74±0.03 (TD6). The knowledge of the heritabilities and correlations among the traits help in developing the prediction models for performance traits which assists in developing better, accurate and faster selection strategies for breeding programs.
The present research was carried out to determine the effect of non-genetic factors on first lactation 305 days and lifetime milk yield of Sahiwal cattle. Data were collected on 392 cows maintained at NDRI, Karnal herd for first lactation 305 days milk yield and on 282 cows for lifetime production, over a period of 31 years (1986-2017). The traits were subjected to least squares analysis using Harvey (model 1) considering season of calving, period of calving and age at first calving as fixed effects. The overall least squares mean for first lactation 305 days milk yield and lifetime milk yield were found to be 1898.95 ± 50.26 and 7241.47 ± 411.18 Kg respectively. The effect of season of calving and age at first calving was found to be non-significant on first lactation 305 days milk yield whereas the effect of period of calving was significantly affecting first lactation 305 days milk yield. The effect of season of calving was non-significant on lifetime milk yield also. Age at first calving and period of calving had a highly significant effect on life time milk yield of Sahiwal cattle. Hence, the data needs to be adjusted for all the significant non-genetic factors so that the data may be used further for genetic analysis.
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