HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Hixon, A. L. Articles by Marks, M. A. Search for Related Content PubMed Articles by Hixon, A. L. Articles by Marks, M. A.

Estimates of Genetic Parameters for Sexual and Compositional Maturity in Gilts¹

The University of Georgia, Athens 30602

Abstract

Crossbred gilts (n = 210) from 12 Duroc and 12 Landrace sires farrowed in six bimonthly farrowing groups were performance tested at the University of Georgia Swine Center. From these gilts, 50 females were selected for extremes in early (12) or late (13) sexual maturity (as measured by age at first detectable estrus); or, for early (13) or late (12) compositional maturity (as measured by backfat at the 10th rib adjusted to a 105-kg basis). Selected females were mated to farrow litters in bimonthly farrowing groups from March 1983 to May 1985. From these litters 370 gilts were tested. Biweekly measurements were taken for weight and fat depth 5 cm off the midline at the 10th rib from 27 to 105 kg. When a pen of four gilts averaged 105 kg they were moved from the test facility to pasture lots. Estrous detection began when the females reached 70 kg and continued until 75% of a test group had cycled. The genetic parameters were estimated by two methods: 1) regression of daughter's performance on dam's performance and 2) the ratio of the response difference of the daughters from the high-low selected dams. Herita-bility estimates for backfat at 105 kg were .56 ± .10 and 1.32 ± .40; heritability estimates of age at first estrus were .11 ± .10 and .24 ± .28, respectively, for the two methods of estimation. The estimated genetic correlations between backfat and age at puberty were .11 ± .28 and .90 ± .08, respectively. Offspring of females selected for early puberty cycled at an earlier age with more fat than offspring of females selected for late puberty. Offspring of females selected for low backfat were leaner and cycled at an earlier age than offspring of females selected for more backfat.

¹ This research was supported by State and Hatch funds allocated to the Georgia Agr. Exp. Sta.

² Anim. and Dairy Sci. Dept.