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University of Helsinki (2015)

Senegalissa käytettyjen lypsyrotujen maitotuotoksen ennustaminen mittalypsytuloksista

Lassila, Lotta

Titre : Senegalissa käytettyjen lypsyrotujen maitotuotoksen ennustaminen mittalypsytuloksista

Auteur : Lassila, Lotta

Université de soutenance : University of Helsinki,

Grade : Master’s Thesis 2015

Résumé
In this master’s thesis the current production level of Senegalese dairy breeds was estimated and a model to predict annual yield based on test day results was developed. With the results of this master’s thesis and the results from the project Senegal Dairy Genetics it was possible to determine the average milk yield of Senegalese dairy breeds. Production records can be further used in planning the feeding and in selection of breeding animals. The results can also be used in socio-economic evaluation of different dairy breeds in Senegal. The data was collected as a part of FoodAfrica programme and its work package Senegal Dairy Genetics which is funded by the ministry for Foreign Affairs of Finland. The lactation curve was modelled for different breed types and on animal level using Wilmink and Wood functions. The modelling was evaluated by coefficient of determination, mean squared error of prediction and by plotting of residuals. Estimated mean cumulative milk yield of 305 days was calculated with estimates obtained by modelling of the lactation curves. The cumulative yield was calculated using modified Interpolation method. There was a clear difference in production level between between breed types. The mean daily milk yield of all animals was 2.6 litres of milk. In the smaller data set the cumulative milk yield of 305 days was 604 litres for pure bred zebu and 1308 litres for zebu and taurine crosses when calculated with the Test Interval Method. In the larger data set the yield of 305 days for zebu was 424 litres. Wilmink function had lower mean squared error of prediction (MSE) than Wood function. The coefficient of determination was slightly higher with Wood function. However, Wilmink function proved to be more accurate and more robust. The estimated yield using the predictions of modelling of the lactation curves was very close to the cumulative yield calculated with the Test Interval Method. Wilmink function was determined fit to predict production records.

Mots clés : lactation curve zebu taurine milk yield laktaatiokäyrä seebu taurine maitotuotos Senegal

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Page publiée le 26 avril 2018