Genetic evaluations for measures of the milk-flow curve in the Italian Brown Swiss population
Open Access
- 1 February 2011
- journal article
- Published by American Dairy Science Association in Journal of Dairy Science
- Vol. 94 (2), 960-970
- https://doi.org/10.3168/jds.2009-2759
Abstract
The objective of this study was to estimate heritabilities and genetic correlations between milk-release parameters, somatic cell score, milk yield, and udder functional traits in the Italian Brown Swiss population. Data were available from 37,511 cows over a span of 12 yr (1997-2008) from 1,592 herds. Milking flows were recorded for each individual once during lactation. Three different analyses were performed to estimate variance components for all the traits of interest. The first analysis included single control data milk yield, somatic cell score, maximum milk flow, average milk flow, time of plateau, decreasing time, and total milking time, whereas the second analysis included milk-release parameters as well as total udder score, udder depth, and 305-d milk yield and somatic cell score as dependent variables. The third analysis included total milking time, 305-d milk yield and somatic cell score, total udder score, udder depth, and ratios of maximum milk flow over total milking time (R1), time of plateau (R2), and decreasing time (R3) to estimate the relationship between the shape of the milk-release curves and important milking traits. Results from the first and second analysis found similar heritabilities for milkability traits ranging from 0.05 to 0.41 with genetic correlations between production traits and flow traits ranging from low to moderate values. Positive genetic correlations were found among production, somatic cell score, and milkability traits. The third analysis showed that R1 had the greatest heritability of the ratio traits (0.37) with large genetic correlations with R2 and R3, a low correlation with 305-d somatic cell score, and no correlation with 305-d milk yield. Estimated responses to selection over 5 generations were also calculated using different indexes, which included either flow or ratio traits. The results of this study show that it is possible to use information collected through portable flowmeters to improve milkability traits. Using a set of variables or traits to describe the overall release of milk can be an advantageous selection strategy to decrease management costs while maintaining milk production.Keywords
This publication has 23 references indexed in Scilit:
- Milk flow pattern, somatic cell count and teat apex score in primiparous dairy cows at the beginning of lactationItalian Journal of Animal Science, 2009
- Heritabilities and Genetic Correlations of Body Condition Score and Calving Interval with Yield, Somatic Cell Score, and Linear Type Traits in Brown Swiss CattleJournal of Dairy Science, 2007
- Interaction of Somatic Cell Count and Quarter Milk Flow PatternsJournal of Dairy Science, 2007
- Genetic parameters for casein and urea contentin the Italian Brown Swiss dairy cattleItalian Journal of Animal Science, 2007
- Estimates of genetic parameters for milkability from automatic milkingLivestock Science, 2006
- Proposal of an udder health genetic index for the Italian Holstein Friesian based on first lactation dataItalian Journal of Animal Science, 2006
- Economic values in dairy cattle breeding, with special reference to functional traits. Report of an EAAP-working groupLivestock Production Science, 1997
- Milking characteristics in dairy cows of different breeds from different farms and during the course of lactationJournal of Animal Breeding and Genetics, 1995
- Genetic relationships between clinical mastitis, somatic cell count, and udder conformation in Danish HolsteinsLivestock Production Science, 1994
- Influence of milk flow rate on new intramammary infection in dairy cowsJournal of Dairy Research, 1991