Growth, composition and palatability of calf-and yearling-fed cloned steers /
| Main Author: | |
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| Other Authors: | , , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1994.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy ProQuest, Abstract |
| Abstract: | Two parallel experiments were conducted to evaluate the impact of calf-versus yearling-feeding on animal growth, performance, carcass and palatability traits of Brangus steers created by nuclear transplantation cloning. Cloned cattle were used to reduce, or eliminate, the normal animal-to-animal additive genetic variation that often clouds many research results. In Experiment 1, steers (n = 8) were fed as weanling calves (CF; n = 4) or yearlings (YF; n = 4) to a constant age endpoint of 16 mo. In Experiment 2, steers (n = 10) were fed as weanling calves (CF; n = 5) or yearlings (YF; n = 5) to a constant live weight of 530 kg. In general, YF cattle gained weight more rapidly, although less efficiently, than CF cattle. The YF steers in this study were leaner with lower numeric yield grades compared to CF steers. Beef industry perception has been that calf-feeding results in lower quality grades as a result of cattle being younger at slaughter than when fed as yearlings. Calf-feeding often has been offered as an "excuse" for lower percentages of U.S. Choice carcasses. Intramuscular fat has been recognized as a later-developing fat depot, and calf-fed cattle have been thought to be young enough so as to not have reached a point on their growth curve where marbling deposition has accelerated. Data from this study demonstrate that, for the Brangus steers used here, the age difference created by feeding calves instead of yearlings is not sufficient to elicit a significant difference in quality grades. In neither of the experiments conducted were there any differences observed with respect to palatability of beef from calf- or yearling-fed cattle of the same breed. Again, this is contradictory to industry perceptions of increased tenderness associated with calf-fed carcasses compared to yearling-fed carcasses of the same quality grade. Cutability differences favored the YF carcasses in both experiments. The differences in cutability observed in Exp. 1 were due largely to the impact of time-on-feed. The CF cattle were on feed over twice as long as the YF cattle in Exp. 1. In Exp. 2, the feeding times were more similar, but the cutability differences remained, indicating that CF cattle should be slaughtered at lighter weights to be comparable in cutability to their YF counterparts. There was a tendency for the CF carcasses in this study to have a higher proportion of s.c. fat and a lower proportion of intermuscular fat than the YF carcasses. In both experiments, YF carcasses had a lower percentage total dissectible fat and a higher percentage muscle than the CF carcasses. There was no difference between the treatments with respect to percentage bone or muscle-to-bone ratio. Data from this study indicate that nuclear transplantation cloning possesses great potential as a tool for reducing the normal animal-to-animal variation observed in cattle and for reducing the number of experimental animals necessary to achieve the desired level of statistical sensitivity. |
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| Item Description: | "Major subject: Animal Science." Vita. |
| Physical Description: | xi, 96 leaves : illustrations ; 28 cm |
| Bibliography: | Includes bibliographical references. |