A COMPARISON OF ALGEBRAIC MODELS TO DESCRIBE THE LACTATION CURVES IN JAFARABADI BUFFALO 3384
dc.contributor.advisor | Dr. N. J. Rankja | |
dc.contributor.author | CHUDASAMA HARSHAL MOHANLAL | |
dc.date.accessioned | 2023-01-21T04:50:16Z | |
dc.date.available | 2023-01-21T04:50:16Z | |
dc.date.issued | 2021-09 | |
dc.description.abstract | The present investigation aims to compare the efficiency of seven Algebraic models with respect to weekly milk yield records of Jafarabadi buffalo. The weekly milk yield (litre) data were collected for 357 record of six lactations covering the period from 2009 to 2018 of the Cattle Breeding Farm, Junagadh Agriculture University, Junagadh. The weekly milk yield records of 43 weeks for each of the six lactations and average of all the six lactations (overall) were subjected to statistical analysis based on seven different models viz., Inverse polynomial, Gamma type, Parabolic exponential, Exponential, Quadratic, Quadratic cum log and model proposed by Morant and Gnanasakthy using non-linear fitting approach. The two criteria employed to judge the efficiency of different models were coefficient of determination (R2) and deviation from regression sum of squares (DSS). Apart from this, different characteristics viz., initial milk yield (litre/week), peak milk yield (litre), time to attain peak milk yield (week), 43rd week milk yield (litre), rate of increase (litre), rate of decrease (litre) and total milk yield (litre/lactation) were estimated and compared with the observed data in each lactation and overall, i.e. average of six lactations. The Quadratic cum log model was found most efficient based on both the criteria i.e. R2 and DSS. Next in order was Gamma model followed by Parabolic exponential for all the six lactations and overall basis (average of six lactations). Since both the criteria i.e. R2 and DSS were highly negatively correlated either of them can be considered for comparing efficiency of different algebraic models. It was also observed that the variation in coefficient of determination (R2) was less for all the models tried in each of the lactation whereas it was comprehensive in the case of deviation from regression sum of squares (DSS). Various useful characteristics of lactation curve viz., initial milk yield, peak milk yield, time to attain peak milk yield, milk yield in 43re week (last week), rising and declining phases and total milk yield were estimated for four out of seven models, i.e. Gamma type model, Quadratic cum log model, Quadratic model and Inverse polynomial model. These models were compared for various characteristics based on observed records. Inverse polynomial model, model proposed by Morant and Gnanasakthy and Exponential models were excluded from comparison as they did not provide logical estimates for these characteristics. Performance of the models varied with the characteristics of milk yield of different lactations. Gamma type model was found most efficient for time to attain peak milk yield and rate of increase. However, Gamma model showed superiority to predict rate of decrease. To predict initial milk yield as well as peak milk yield, Quadratic cum log model was found superior as compared to rest of the models. Quadratic model less efficiency to estimate various characteristics of milk yield records of Jafarabad buffalo | en_US |
dc.identifier.uri | https://krishikosh.egranth.ac.in/handle/1/5810192624 | |
dc.keywords | afarabadi buffalo, lactation, lactation curves, Algebraic models, coefficient of determination (R2), Deviation from regression sum of square (DSS), Milk yield. | en_US |
dc.language.iso | English | en_US |
dc.pages | 78 | en_US |
dc.publisher | JAU JUNAGADH | en_US |
dc.sub | Statistics | en_US |
dc.theme | A COMPARISON OF ALGEBRAIC MODELS TO DESCRIBE THE LACTATION CURVES IN JAFARABADI BUFFALO 3384 | en_US |
dc.these.type | M.Sc | en_US |
dc.title | A COMPARISON OF ALGEBRAIC MODELS TO DESCRIBE THE LACTATION CURVES IN JAFARABADI BUFFALO 3384 | en_US |
dc.type | Thesis | en_US |
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