New Zealand Journal of Agricultural Research abstracts

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Genetic studies of carotenoid concentration in the plasma and milk of New Zealand dairy cattle

C. A. MORRIS¹
T. W. KNIGHT²
S.-A. N. NEWMAN²
S. M. HICKEY¹
A. F. DEATH²
K. T. O’NEILL²
M. RIDLAND²

¹AgResearch
Ruakura Research Centre
Private Bag 3123
Hamilton, New Zealand

²AgResearch
Grasslands Research Centre
Private Bag 11008
Palmerston North, New Zealand

Abstract  Blood and milk samples were collected in 1992/93 from 2-year-old heifers in the Livestock Improvement Corporation’s Sire Proving Scheme, for analysis of carotenoid concentration (CC). The trial comprised heifers in 127 springcalving North Island dairy herds, where blood samples were taken from a total of 2744 heifers (Holstein-Friesians (F), Jerseys (J), and their crosses) in early/mid lactation (spring), and from a sub-group of the same animals in autumn. These heifers were the daughters of 157 young F and J sires, and 15 older sires. Whole-lactation yields of milk, fat, and protein, and fat% and protein% were also obtained. Sire-model restricted maximum likelihood (REML) analyses were carried out to estimate genetic and phenotypic parameters. Purebred F and J breed means for plasma CC in spring were 14.1 and 17.9 µg ml^–1 (P  0.001), respectively, and for milk CC 5.24 and 7.50 µg g^–1 fat (P 0.001), and corresponding heritabilities for the two traits were 0.46 ± 0.08 and 0.11 ± 0.10. The repeatability of plasma CC across seasons was 0.64 ± 0.02. The genetic correlation between spring plasma CC and milk CC g^–1 fat was 0.66 ± 0.22, whereas genetic correlation estimates for spring plasma and milk CC g^–1 fat with other traits were: with milk volume –0.01 ± 0.16 and 0.41 ± 0.35, with fat yield 0.06 ± 0.22 and 0.29 ± 0.54, and with fat% 0.03 ± 0.13 and –0.26 ± 0.29. It was concluded that plasma CC was a repeatable and heritable trait, whereas milk CC g^–1 fat was lowly inherited; plasma CC was essentially uncorrelated with the standard milk production traits; if bulls were selected for lower plasma CC, there would be reduced CC in both the plasma and milk of their daughters.

Keywords  cattle; carotenoid concentration; heritability; genetic correlation; milk; plasma

Received 14 August 2001; accepted 12 December 2001
New Zealand Journal of Agricultural Research, 2002, Vol. 45: 27–33
0028–8233/02/4501–0027 $7.00/0 © The Royal Society of New Zealand 2002

PDF file of entire paper: Print-quality

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