In the first study performance data from 465 Boer goat rams tested in a central performance test
in the Northern Cape Veld-Ram Club from 1989 to 2007 were analysed to determine the
relationship between performance and sale price. Rams were subjected to extensive management
conditions on natural pastures for 160 days and finished-off in a feedlot for 50 days. Upon the
conclusion of the entire test period, the rams were auctioned. Performance information was
available for buyers for decision making. Traits analysed included final weight (FW), final
weight index (FWI), average daily gain (ADG), average daily gain index (ADGI), growth per
day of age index (ADOI), Kleiber ratio (KR), auction weight (AW), scrotal circumference (SC),
selection index (SI) and sale price (SP). Stepwise regression analyses, using proc GLM of SAS
were performed to identify variables that significantly influenced sale prices. Final weight was
significant in eight out of eighteen years, auction weight was significant in six of the seven
years measured and selection index influenced prices in seven out of ten years. Scrotal
circumference, average daily gain, final weight index, average daily gain index and Kleiber
ratio had little influence on sale price. Growth per day of age index did not show any influence
on sale price.
Price was positively correlated (P<0.05) with many of the performance traits. All significant
correlations were moderate to high and ranged from 0.37 to 0.80. The amount of variation in
sale price accounted for by the performance traits ranged from 15% in year 1991 to 65% in 1998.
The most important traits influencing sale price (SP) were final weight, auction weight, and
selection index. The results indicated that buyers of stud rams put more emphasis on production traits such as body weight and that they recognize the importance of performance data as shown
by their preference for animals with high selection indices.
In the second study data consisting of 3855 records and collected from 1998 to 2008 were
analysed to estimate genetic parameters for economic traits in two Boer goat flocks. The traits
investigated were weaning weight and post-weaning weight. Least square analysis was used for
estimation of environmental effects. Genetic parameters were estimated from single and bivariate
trait analyses using ASREML software fitting animal models. By ignoring or including maternal
additive genetic effects and their covariance and maternal permanent environmental effects
seven different models were fitted for each trait. The fixed effects of sex, type of birth, age of
dam, year of birth, herd, season and age of lamb, were all significant (P<0.05) for both traits. The
direct heritability estimates varied from 0.24 for weaning weight to 0.31 for post-weaning
weight. The corresponding maternal permanent environment due to the dam was 0.10 and 0.44
respectively. The maternal heritability (0.03) for weaning weight was lower than its
corresponding direct heritability. Estimates of genetic parameters in this study confirmed that
selection for weaning weight would result in genetic improvement of Boer goats.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-09062010-123941 |
| Date | 06 September 2010 |
| Creators | King, Felix Joao Manuel |
| Contributors | Prof FWC Neser, Mr MD Fair |
| Publisher | University of the Free State |
| Source Sets | South African National ETD Portal |
| Language | en-uk |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.uovs.ac.za//theses/available/etd-09062010-123941/restricted/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University Free State or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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