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941.
1. Direct and correlated responses were determined after five generations in four lines of chickens selected either for increased body‐weight gain (line W), for increased food consumption (line F), for decreased food conversion ratio (line E), or at random (line C).

2. Realised heritability estimates calculated after five generations of selection were : 0–37 + 0.04 for weight gain (WG); 0.44 + 0.05 for food consumption (FC); 0.21 + 0.04 for food conversion ratio (FCR).

3. Realised genetic correlation estimates were: WG and FC, +0.71 ±006; WG and FCR, ‐0.40±0.09; FC and FCR, +0.27 + 0.09.

4. Zero‐generation heritability and genetic correlation estimates were greater than the realised estimates, and sex linkage appeared to be important in the expression of all three traits.

5. The genetic correlation between FC and FCR was asymmetrical with considerable positive response in FCR in line F (rg = +0.79) but negligible response in FC in line E (rg = —0.01).

6. There was an apparent plateau in response in FCR in line E from the third to the fifth selected generations.  相似文献   

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An 11-month-old male Miniature Poodle was found to regurgitate small volumes of fluid and food particles due to a diverticulum in the thoracic oesophagus. The diverticulum was removed surgically. Histologically the wall contained extensive scar tissue. Longterm recovery was uneventful and 5 months after surgery the dog is in good health  相似文献   
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Cellular immune responses of peripheral blood lymphocytes to canine distemper virus and measles virus were determined in vaccinated or infected gnotobiotic dogs, using the technique of syncytia inhibition. Cross-reactivity between viruses was detected in both groups of dogs. Peak responses in vaccinated dogs occurred 11 days after vaccination and declined to base-line levels by 3 weeks, whereas responses in infected dogs were present 30 days after inoculation. Fractionation experiments with peripheral blood lymphocytes indicated that synctia inhibition is probably mediated by T lymphocytes.  相似文献   
949.
Investigation of hereditary multiple exostoses in horses under controlled research conditions for 10 years and epidemiologic studies that have spanned up to five generations of human families contain notable similarities. The present study demonstrated that a single dominant autosomal gene is responsible for hereditary multiple exostoses in horses and man. Affected individuals transmit this trait to approximately 50% of their progeny, whereas nonaffected individuals do not transmit the condition to their offspring. The tumors in affected horses are most often present at birth. They tend to be bilaterally symmetrical and vary in size, shape, and texture. Those on the legs generally do not appear to enlarge as the animal matures, but others, notably those on the ribs and scapulae, enlarge until skeletal maturity, Histologically, the tumors appear as typical ostosteochondromas in both horse and man. Sarcomatous transformations have not yet been detected after 10 years in horses, although such changes are occasionally reported in the similar disease condition in man. The remarkable similarities of hereditary multiple exostoses in the horse to that in man provide an opportunity for comparative biomedical study.  相似文献   
950.
Fourteen neonatal dogs (4 through 11 days of age) were exposed orally to the Purdue strain of transmissible gastroenteritis (TGE) virus, and six dogs of similar age were noninoculated controls. Clinical signs of enteric disease did not develop. Both exposed and control dogs had normal fecal passages and appetite throughout the experiment. Jejunal epithelium from dogs euthanatized at 12, 24, 48, and 96 hours and at 10 days after exposure did not exhibit morphologic alterations detectable by light microscopy. Electron microscopic examination indicated that jejunal epithelial cells contained TGE viral particles as early as 12 hours after dogs were exposed. There were no apparent morphologic alterations or signs of desquamation of virus-infected cells, however. Results of pig transmission studies indicated that viable TGE virus was in jejunal tissue of the dogs as early as 12 hours and as late as 10 days after exposure to the virus.  相似文献   
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