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 Urick, J. J. Articles by Blackwell, R. L. Search for Related Content PubMed Articles by Urick, J. J. Articles by Blackwell, R. L.

Comparison of Two- and Three-Way Rotational Crossing and Synthetic Variety Production Involving Inbred Lines of Hereford Cattle: Preweaning and Weaning Traits¹

US Department of Agriculture and Montana Agricultural Experiment Station, Miles City 59301, Cooperating

Abstract

Data for this study were collected from 1967 to 1975 and consisted of the records for 558 straight line (SL) calves of four inbred lines, 212 two- (2W) and 242 three-way (3W) rotational crosses and 112 synthetic variety (SV) calves, all of the Hereford breed. The bull (M) and heifer (F) calves, raised on native range without creep feed, were weaned at an average age of 189 days. Average inbreeding percentages of calves and dams in the four inbred lines were 28.5 and 28.7%, respectively. Average percentage increases over SL shown by 2W, 3W and SV (M and F calves combined over three generations) were: 5.8, 4.9 and 2.0, respectively, for birth weight; 8.2, 11.6 and 10.8 for weaning weight, and 7.2, 10.5 and 9.3 for 180-day gain. All estimated increases over SL within sex of calf were significant except that for birth weight of M and F in SV. The differences between heterosis levels of 2W and 3W were consistently in favor of 3W, and high levels of heterosis in each system were maintained from one generation to the next. The 3W system excelled (P<.05) the 2W system in heterosis for weaning weight and 180-day gain of heifers. M and F calves from SV ranked between 2W and 3W in all traits except birth weight. M calves from SV showed a smaller increase in birth weight over SL than did M calves from 2W and 3W.

¹ This study was conducted at the Livestock and Range Research Station, Miles City, MT, in cooperation with the Montana Agr. Exp. Sta., Bozeman. Publication has been approved by the Director of the Montana Agr. Exp. Sta., as Journal Series No. 851.

² Livestock and Range Research Sta., Western Region, SEA, USD A, Miles City, MT 59301.

³ Present address: Biometrical Services, SEA, USDA, Fort Collins, CO 80521.

⁴ Montana Agr. Exp. Sta., Bozeman 59717.

⁵ Authors express appreciation to Dr. J. S. Brinks of the Colorado Agr. Exp. Sta. for his contribution to the planning of the experiment, and to Mr. W. C. Russell, Graduate Research Assistant, Colorado State Univ., for assistance with data processing.