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in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association



To test the immunocompetence of isogenic families of rainbow trout by measuring their ability to accept or reject skin grafts.


3 families of isogenic rainbow trout (Oncorhynchus mykiss), produced by mating homozygous females and homozygous males, plus 4 Chinook salmon (O tshawytscha) were used in these experiments.


Grafts (allografts, members of the same family; autografts, donor and recipient were the same fish; and xenografts, O tshawytscha as donor) were exchanged. Grafts were applied on day 0 and removed on day 21, placed in neutral-buffered formalin, and embedded in paraffin. Lymphocytes and nuclei were counted in representative stained sections in the epidermis, dermis, and hypodermis. Results were analyzed by univariate analysis, using the Shapiro-Wilk statistic.


Autografts were retained and minimal histologic changes were apparent. Allografts were histologically similar to autografts. Xenografts were rejected.


Results indicate that the immune system of isogenic rainbow trout is unable to distinguish between family members within isogenic families, but that a vigorous response is mounted against Chinook salmon xenografts. The isogenic rainbow trout are immunocompetent with respect to the phenomenon of graft rejection. (Am J Vet Res 1996;57:1576–1579)

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in American Journal of Veterinary Research


Metabolic and production responses are reported for 72 cows treated with bovine somatotropin (bst) for 30 days starting at day 70 of lactation. Of these 72 cows, 48 had been exposed in the preceding lactation to long-term treatment with bst at 3 dosages and 24 (controls) had not been given bst. Approximately half of the cows in each group were parity-2 cows, the rest were older. Comparisons between groups were made separately for parity-2, and older cows.

Analyses, using pretreatment values of each variable as a covariate, indicated that older cows, but not parity-2 cows, significantly (P < 0.05) increased milk production during treatment. Parity-2 cows, however, had a significantly higher milk fat percentage than controls following treatment. Cows treated with 51.6 or 86 mg bst/d in both parity groups had significantly higher serum-free fatty acids than controls. Estimated net energy balances were significantly lower for older treated cows, but did not significantly differ from controls for parity-2 treated cows. Older cows in the 86 mg of bst/d group tended to have higher concentrations of blood glucose than did older control-group cows. Treatment with bst did not significantly increase serum ketone concentrations in any group of animals, and none of the cows developed clinical ketosis during this period.

Estimated net energy balance (eneb) during treatment was a significant (P < 0.05) covariate for free fatty acid concentrations in older cows and for milk fat percentage in parity-2 cows. Covariate adjusted analyses, using eneb during treatment as a covariate, indicated that lipolytic stimuli already acting may be enhanced by treatment with bst, but a negative energy balance was not a necessary precondition for free fatty acid concentrations to increase following somatotropin treatment. Similarly, milk fat percentages for parity-2 treated cows were significantly (P < 0.05) higher during treatment than controls when eneb during treatment was used as a covariate.

Increased milk fat concentrations in parity-2 treated cows were not associated with significant increases in the ratio of C18:C4-10 milk fatty acids, indicating that increased milk fat resulted from either an increase in incorporation of C18 fatty acids into milk fat coupled with an increase in de novo mammary synthesis of C4-10 milk fatty acids or an increase in C12-16 fatty acids that may arise either from increased tissue mobilization, from diet, or from de novo mammary synthesis.

Free access
in American Journal of Veterinary Research