Genetic relationships between persistency and reproductive performance in first-lactation
Data for this study consisted of TD milk yield records of first-lactation Holstein Friesian cows that calved from 1997 to 2013 and belonged to two different herds.
The overall average TD milk yield during first-lactation for Holstein Friesian cows in Ethiopian herds was 11.
2013) have reported no trend for heritability estimates working on first-lactation Holstein cattle.
6], using data from Holstein cows found similar results, reporting that the genetic correlation for first-lactation
milk and calving interval (CI) was unfavorable.
Peak milk production was also similar for each group, both for first-lactation
cows and those in later lactations.
Genetic parameters for test-day electrical conductivity of milk for first-lactation
cows from random regression models.
Cilek and Sahin (2009) attributed the lower heritability for all lactation milk yields than the heritabilities of first and second lactations to culling and selection that may have reduced the phenotypic variance of older cows compared to first-lactation
Various reports have shown that when accelerated diets are fed before puberty then breeding age and AFC but also first-lactation milk yield (MY) decrease (Gardner et al.
2006a), sometimes referred to as fatty udder syndrome, thereby affecting future first-lactation MY potential of the animal (Gardner et al.
Body conditions of first-lactation Holstein cows were scored twice every month from June 2006 to October 2007 at the National Livestock Breeding Center Niikappu Station (Hokkaido, Japan).
In conclusion, peak yield and total milk yield were negatively correlated with BCSs and its change in mid- to late lactation in first-lactation cows, suggesting that cows with high levels of lactation have low body reserves and health status in mid- to late lactation and thus delayed recovery of body reserves.