Indian dairy sector plays a vital role in building nation’s economy and ensuring rural livelihood. India now ranks first in milk production among the countries of the World. The contribution of exotic and crossbred cow to this high milk output is greater, producing nearly half of the total milk in Tamil Nadu. The lactation curve is the graphical representation of milk yield over time, having two parts - a rapid increase from calving to peak in early stage of lactation and a gradual decline from peak to the end of lactation. Various models had been tried by different researchers to fit lactation curves in dairy cattle. Configuration of lactation curve is important economically, as the animals producing milk yield at a moderate level throughout the lactation is preferred over those which produce more at the peak, but little thereafter. The advantages of lactation curves are predicting milk yield with less error and using it in sire selection, besides making decisions for determining strategies replacement of dairy cows. This book compares different models to fit lactation curves in different breeds to identify the best model to predict milk production.