Graduate Thesis Or Dissertation
 

Performance of three inbred lines of Herford cattle and their linecrosses

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  • Three inbred and relatively unrelated lines of Hereford cattle (1. Lionheart, 2. Prince, and 3. David) developed at the Corvallis branch of the Oregon Agricultural Experiment Station as part of the W-1 project of the Western States were crossed annually from 1963 through 1965 inclusive. Data on 137 inbred and linecross calves born during the three-year period were analysed for four production traits: birth weights, suckling rates of gain, average daily gains and feed efficiency (pounds of feed per 100 pounds of gain). There were 79 male and 58 female calves. Twenty-three of the male calves were inbred while 56 were linecross calves. There were 16 inbred and 42 linecross female calves. The purpose of the study was to compare the mean performance of any two inbred lines used to make crosses with the mean performance of their reciprocal linecrosses for possible heterotic effects. All possible diallelic crosses were made among the three lines in each year and all calves were weaned and feed-tested on a constant-weight basis. Male calves were feed-tested from 450 to 800 pounds and again between 800 and 1000 pounds while female calves were feed-tested from 400 to 750 pounds. They were fed all they could eat for three hours each morning and three hours each evening. The ration and other management details are described. Selection was on an index basis with automatic culling for inherited defects and abnormalities. Results were reported separately for bull and heifer calves. Comparisons were mostly on a within-sex basis and always on a within-line basis. For both male and female calves, there was no significant difference between the mean birth weights and mean suckling rates of gain of inbred calves and their reciprocal linecross relatives. There was a non-significant difference between male, and female inbred and linecross calves. There was more variability among female than among male calves in suckling gains. On the average, linecross calves of both sexes at younger ages within lines gained more rapidly and were more efficient than inbred calves, with the exception of the 2 x 3 + 3 x 2 linecross male calves which gained slightly less than their inbred relatives between 450 and 800 pounds body weight. The 1 x 2 + 2 x 1 linecross heifers were significantly superior (P < 0.01) by 0.28 pounds per day and showed a saving of about 113 pounds of feed per 100 pounds of gain over their inbred relatives. All linecross calves were non-significantly more efficient in feed utilization than their within-line inbred relatives and there were indications of more heterosis in female than male linecrosses. However, in the 800 to 1000 pound feed test period in the males, the mean daily gain and mean feed efficiency of each pair of inbred lines exceeded those of the respective reciprocal linecrosses. This reversal of growth rate and economy of gains between linecross and inbred calves within the 800 to 1000 pound feed-test period seems to indicate that inbred calves of the same chronological age with linecross calves are physiologically younger and consequently less rapid and less efficient in rate and economy of gains at earlier ages. The implication here is that inbreeding depresses early production traits more than it does later-life traits. Because of the low heterotic effects obtained in this study, the suggestion is being made that, in future crosses of these inbred lines, linecross calves from linecross dams be compared with inbred calves from inbred dams since it is known that inbreeding of both dam and calf affect the performance of the calf.
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file details MunjiMarcus1967.pdf 2017-08-23 Pubblico Scaricare