1. All age groups gained mass during the active season, but mass-gain of adult females was delayed during lactation. 2. The relationship of body mass to metabolic rate varied widely; when the relationship was significant, R2 varied from 10.3 to 72.6%. Body mass affects VO2 more during lactation than at any other period. 3. Mean VO2 of adult males was higher in June than that of adult, non-lacta...

Estimating (co)variance parameters of a random regression model for test day yields of dairy cattle has been proven to be a challenging task due to the complexity of (co)variance structure of the test day yields. Two common approaches have been practised so far for the estimation of parameters: direct random regression model approach and indirect covariance functions (CF) approach. Animal genet...

Genetic parameters were estimated with restricted maximum likelihood for individual test-day milk, fat, and protein yields and somatic cell scores with a random regression cubic spline model. Test-day records of Holstein cows that calved from 1994 through early 1999 were obtained from Dairy Records Management Systems in Raleigh, North Carolina, for the analysis. Estimates of heritability for in...

Genetic evaluations for milk yield of Holsteins in Mexico were computed from lactation and pedigree information from Holstein de México. The US animal model system for national evaluations was adapted for Mexico. The primary change was in defining unknown-parent groups. Paths of unknown parents of bulls and sires of cows were combined and separate unknown-parent groups defined for parents of US...

OBJECTIVE Women at risk for delayed onset of lactation are often advised to pump their breasts before lactogenesis stage II to hasten the timing of this process. The effectiveness of this clinical practice has not been previously evaluated. This study investigates the effects of breast pumping before the onset of lactation on early milk transfer and subsequent breastfeeding duration among women...

A spline animal model was fitted to 152,103 test-day milk, fat, and protein yield records from 14,423 first-lactation cows. The models included age at calving and the herd-test-month as fixed effects. Model fitting was carried out using Restricted Maximum Likelihood with ASREML. For milk yield, the heritability at 18 d in milk was 0.19, which increased to the maximum estimated value of 0.23 at ...

ABSTRACT Genetic selection for improved feed efficiency in dairy cattle has received renewed attention over the last decade to address needs of a growing global population. As milk yield is critical component metrics animals, our objective was evaluate associations between primiparous Holstein and parameters mathematical model describing individual lactation curves. The Dijkstra curve ...

The objective of this study was to identify the best random regression model using Legendre orthogonal polynomials to evaluate Alpine goats genetically and to estimate the parameters for test day milk yield. On the test day, we analyzed 20,710 records of milk yield of 667 goats from the Goat Sector of the Universidade Federal de Viçosa. The evaluated models had combinations of distinct fitting ...