New Zealand Journal of Agricultural Research abstracts

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Genetic parameters for milk yield and faecal nematode egg count in Saanen does

C. A. MORRIS
M. WHEELER

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

B. C. HOSKING

Novartis New Zealand Ltd
Private Bag 19980
Avondale
Auckland 7, New Zealand

T. G. WATSON

Pfizer Pty Ltd
P O Box 57
West Ryde, Sydney
NSW 2114, Australia

A. P. HURFORD

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

B. J. FOOTE
J. F. FOOTE

Kaimamaku
RD 4, Hikurangi
Northland, New Zealand

Abstract  Results of two herd tests per lactation (each comprising daily milk yield and yield of fat and protein (FP)) and faecal nematode egg counts (FEC) on Saanen does in Northland, New Zealand, were recorded during the lactations of 1991/92 to 1996/97. The data were used to estimate genetic parameters for milk yield and FP, and for FEC. A total of 4738 records from 1161 does, the daughters of 53 sires, were available. Restricted maximum likelihood procedures with an animal model were used for analyses. Overall, daily yields of milk and FP were 1.40 litres and 0.091 kg (average concentration 64.4 g/litre). Among the five age classes of doe, milk yield ranged from 0.93 to 1.80 litres, while FP ranged from 0.061 to 0.117 kg. Geometric mean FECs ranged from 974 to 1241 eggs/g faeces among does of different ages, and from 748 to 3093 eggs/g among years (lactations). There was a curvilinear relationship between all three traits and days in milk, with declining yields and FEC as lactation progressed.

The heritabilities (h²) for milk yield and FP averaged 0.23 +/- 0.04 and 0.27 +/- 0.04, respectively, with corresponding repeatability (r) values of 0.26 +/- 0.03 and 0.27 +/- 0.03. Estimates of h² for loge (FEC+100) across years were 0.09 +/- 0.05 (mid lactation) and 0.06 +/- 0.04 (late lactation), with corresponding r values of 0.09 +/- 0.06 and 0.15 +/- 0.04. The genetic correlation between milk yield and FP was 0.87 +/- 0.03, and those between FEC and milk yield or FP were -0.21 +/- 0.26 and -0.17 +/- 0.24, respectively. Phenotypic correlations between milk yield and FP, FEC and milk yield, and FEC and FP averaged 0.88 +/- 0.01, -0.07 +/- 0.03, and -0.07 +/- 0.03, respectively.

Keywords  heritability; milk yield; nematodes; faecal egg count; Saanen goats

New Zealand Journal of Agricultural Research, 1997, Vol. 40: 523-528

0028-8233/97/4004-0523 $7.00/0 (c) The Royal Society of New Zealand 1997

PDF file of entire paper: medium quality (445K); (scanned from paper original: notes about this process)

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