New Zealand Journal of Agricultural Research abstracts
Genetic trend and parameter estimates for milk yield traits and kidding date in a Saanen goat herd in New Zealand
C. A. Morris
M. Wheeler
M. Lanuzel
AgResearch
Ruakura Research Centre
Private Bag 3123
Hamilton, New Zealand
Abstract Data from a large herd of Saanen goats
were analysed to investigate the genetic variation in milk production
traits and kidding date (KD), and genetic relationships between them.
The analysis involved 14 years of milk yield data
(1991/92–2004/05), comprising 20 296 herd-test records for
daily milk yield (litres (L)) and milk solids yield (fat and protein
(FP)) from two to four annual herd tests per individual doe, and 5 years of KD data (2000/01–2004/05) comprising a total of 3548 records.
Herd size increased over the 14 years from 180 to 820 herd-tested does
per season. Lactating does were managed outdoors on pasture until
1995/96. Progressively from 1996/97 part of the milking herd was moved
to covered yards and, from 2001, pasture and supplements were carried
year-round to all milking does and young stock in covered yards. After
the herd-establishment years, there were few purchased bucks (19% since
1998), and 94% of does recorded in the milking herd were homebred.
Kidding was seasonal. Does were not synchronised for mating. In
2000–04, the KD range averaged 122 days in mixed-aged does, with
mainly single-sire matings. Herd-test yields and kidding data were
analysed using restricted maximum likelihood, with a repeated-animal
model and full relationship matrix. Single-trait heritability estimates
for L, FP, and KD were 0.35 ± 0.03, 0.30 ± 0.03, and 0.14
± 0.03, respectively, and corresponding repeatabilities were
0.52 ± 0.01, 0.47 ± 0.01, and 0.24 ± 0.02. The
genetic correlation between FP and KD was 0.14 ± 0.09. Genetic
selection for FP over 13 years has achieved a 3.1 ± 0.19% annual
rate of progress. The consequences of later kidding from does with
genetically higher daily yields are discussed, in relation to future
management and selection plans.
Keywords goat; Saanen; heritability; milk yield; kidding date; genetic correlation
A05049; Received 17 October 2005; accepted 24 March 2006; Online publication date 9 May 2006
New Zealand Journal of Agricultural Research, 2006, Vol. 49: 175–181
0028–8233/06/4902–0175 © The Royal Society of New Zealand 2006
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