title: Effect of thiouracil on response to heat stress of White Leghorn lines selected for fast and slow gain in two temperatures.
abstract: Four lines of White Leghorns previously selected for fast and slow gain from 5 to 9 weeks of age in a hot (32.2 C) and in a cold (21.1 C) selection environment were grown from 5 to 9 weeks in the same two temperature environments. Samples of 32 females from each line of the third generation grown in each temperature environment from 5 to 9 weeks of age were divided into two groups; one received .2% thiouracil in the diet for a 5-day period and the other did not. The temperature was then increased to 40.6 C until 52.8% of all birds had died. The percentages of mortality of lines, rearing environments, and thiouracil treatments were then analyzed. An increase of 64.8% mortality from acute heat stress for birds reared in the cold environment was significant, but the differences among the four selected lines were not. The presence of thiouracil in the diet significantly reduced mortality from heat stress by 16.4%. There were no significant interactions between thiouracil treatments and selected lines or rearing environments.
mesh_terms: D000064:Acclimatization / Q000187:drug effects*; D000284:Administration, Oral; D000818:Animals; D002645:Chickens / Q000254:growth & development; D005260:Female; D006358:Hot Temperature; D011201:Poultry Diseases / Q000401:mortality* / Q000517:prevention & control; D013312:Stress, Physiological / Q000401:mortality / Q000517:prevention & control / Q000662:veterinary*; D013696:Temperature; D013889:Thiouracil / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D013889:Thiouracil