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Titolo:
Estimates of genetic parameters for daily somatic cell count of AustralianDairy Cattle
Autore:
Haile-Mariam, M; Goddard, ME; Bowman, PJ;
Indirizzi:
Univ Melbourne, Inst Land & Food Resources, Parkville, Vic 3052, AustraliaUniv Melbourne Parkville Vic Australia 3052 arkville, Vic 3052, Australia Victorian Inst Anim Sci, Dept Nat Resources & Environm, Attwood, Vic 3049,Australia Victorian Inst Anim Sci Attwood Vic Australia 3049 od, Vic 3049,Australia
Titolo Testata:
JOURNAL OF DAIRY SCIENCE
fascicolo: 5, volume: 84, anno: 2001,
pagine: 1255 - 1264
SICI:
0022-0302(200105)84:5<1255:EOGPFD>2.0.ZU;2-X
Fonte:
ISI
Lingua:
ENG
Soggetto:
TEST DAY RECORDS; CLINICAL MASTITIS; MILK; LACTATION; SCORE; TRAITS; COWS; HERITABILITIES; HOLSTEINS; AYRSHIRE;
Keywords:
daily somatic cell count; random regression; genetic parameters;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Citazioni:
30
Recensione:
Indirizzi per estratti:
Indirizzo: Haile-Mariam, M Univ Melbourne, Inst Land & Food Resources, Parkville, Vic3052, Australia Univ Melbourne Parkville Vic Australia 3052 52, Australia
Citazione:
M. Haile-Mariam et al., "Estimates of genetic parameters for daily somatic cell count of AustralianDairy Cattle", J DAIRY SCI, 84(5), 2001, pp. 1255-1264

Abstract

Genetic parameters for daily somatic cell counts (SCC) of the first three parities were estimated for Australian Dairy Cattle. Most of the data analyses were carried out with a sire random regression model. The estimates were compared with those from conventional ten-trait analyses and animal models. In the first-parity estimates of heritabilities (h(2)) were low (0.04 to0.05) at the beginning of the lactation and higher (0.11 to 0.13) at the end. The average h(2) estimated from random regression sire model, random regression animal model and conventional multitrait sire model were 0.09, 0.09, and 0.08, respectively, in the first lactation. The average h(2) were 0.09 and 0.11 in the second and third parities, respectively. Genetic correlations between daily log, SCC within parity were high for adjacent tests (nearly 1) and low (as low as 0.30) between the beginning and the end of the lactation. Generally, the genetic correlations between parities depend on how far apart they are and on whether they are on the same day in any two parities. Across parities, on average, genetic correlations between parities 1and 3 were the lowest and those between 1 and 2 intermediate, while those between 2 and 3 were the highest. The estimated environmental correlations were lower than the genetic correlations, but the trends were generally similar. Differences in genetic parameter estimates due to model were small, except for some genetic correlations. The high residual error variances, thelow h(2), and the inconsistency in genetic correlations that were observedparticularly at the beginning of the first lactation suggest that log, SCCearly in the first lactation may be related to a spike in SCC as result ofinfection and (or) onset of lactation while SCC later in lactation represents a sustained response to infection. Accounting for the variation in heritabilities and correlations should improve the accuracy of genetic evaluations for SCC based on test day records.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 27/09/20 alle ore 21:14:55