Articles Related to lactation
The records of 1198 crossbred cattle sired by 68 bulls were analyzed to estimate breeding values of sires using animal model Restricted Maximum Likelihood (REML), best linear unbiased prediction (BLUP), least squares methods (LSM) and simple daughter average ( D ) sire evaluation methods. The error variance of breeding values of sires were estimated and used in computing the relative efficiency of different sire evaluation methods. In the present study the least squares methods (LSM) have the lower error variance for Age at First Calving (AFC), First lactation milk yield (FLMY) and Lifetime lactation length (LTLL), while (BLUP) methods have the lower error variance for First lactation period (FLP), First dry period (FDP), First calving interval (FCI), First service period (FSP) and Lifetime milk yield (TLMY) as compared to other methods and accordingly, it was adjudged the most efficient sire evaluation method. In the present study, the higher value of coefficient of variation showing, there was very large variation in the herd for most of the traits under study. It indicated that the BLUP method is the best over the other three methods because estimated value of relative efficiency by BLUP method had smaller values than that of the other three methods. On the basis of the error variances of breeding values of sires the BLUP method was found most efficient sire evaluation method.
The discovery of the presence of stem cells and precursors with high regenerative potential in the mammary gland, hypothetically maintained throughout the course of the productive life of the dairy cow sheds an interesting perspective in the research which is interested to clarify all physiological clues and possible solutions to increase or maintain longer the potential production of dairy cows during life span of lactation.