We first sought to clarify the effects of discounted rate, survival rate, and lactation persistency as a component trait of the selection index on net merit, defined as the first five lactation milks and herd life (HL) weighted by 1 and 0.389 (currently used in Japan), respectively, in units of genetic standard deviation. Survival rate increased the relative economic importance of later lactati...

emphasis on milk yield (my) as well as milk yield persistency (myp) and calving interval (ci) is necessary to achieve more sustainable productionin dairy cattle. therefore the main objective of this study was to find an optimum regression model to estimate economic values for my, myp and ci.using a deterministic bio-economic model, seventyfiveproduction states differing mainly in my, mypand ciw...

in this research, in order to describe milk production traits lactation mahabadi goat breed, seven statistical functions were fitted using 1665 milk production traits records and 833 body weight records. the milk production traits were milk yield, fat percent, fat yield, protein percent, protein yield, lactose percent and snf percent. these records have been recorded on 123 goats during years o...

Forty Holstein dairy cows in their first and second lactation were used in a lactation study from 4-week prepartum through 14-week postpartum to investigate the potential effect of feeding different levels of ruminally protected methionine and choline on milk yield persistency of Holstein dairy cows. Cows were randomly assigned to receive one of the following treatments: 18 g/d of rumen-protect...

Lactation curves are a graphical representation of the milk production profile of a doe from parturition to drying up. Their shape provides information about the productivity of the doe and offers a means of explaining features of the milk production patterns of each animal. A total of 2732 daily morning milk records from 610 does of the Kenyan Alpine dairy goats’ genetic groups (50% Alpine, 75...

Multivariate factor analysis and principal component analysis were used to decompose the correlation matrix of test-day milk yields of 48,374 lactations of 21,721 Italian Simmental cows. Two common latent factors related to level of production in early lactation and lactation persistency, and 2 principal components associated with the whole lactation yield and persistency were obtained. Factor ...

The objective of this study was to apply factor analysis to describe lactation curves in dairy buffaloes in order to estimate the phenotypic and genetic association between common latent factors and cumulative milk yield. A total of 31 257 monthly test-day milk yield records from buffaloes belonging to herds located in the state of São Paulo were used to estimate two common latent factors, whic...

Variace / covariance components of 227118 first lactaiom test-day milk yield records belonged to 31258 Iranian Holstein cows were estimated using nine random regression models. Afterwards, different measures of persistency based on estimation breeding value were evaluated. Three functions were used to adjust fixed lactation curve: Ali and Schaeffer (AS), quadratic (LE3) and cubic (LE4) order of...

determination of milk yield potential using an accurate method is essential for assessing nutritional requirements, evaluation of genetic potential, lamb growth and survival, management decisions and improving performance traits of sheep flocks. exogenous oxytocin injection is applied to estimate milk secretion rate in sheep. oxytocin is a neurohormone produced in the hypothalamo-neurohypophysi...