SUMMARYTwenty-four laying turkey hens shown to be free of antibodies to turkey.rhinotracheitis virus were inoculated intranasally with an isolate of the virus. A mild respiratory disease developed between 5 and 9 days post infection (pi). Two birds were selected at random at intervals between days 1 and 20 pi, killed and tissues examined for the presence of virus. At autopsy between days 2 and 12 abnormalities were found in the oviducts including the deposition of inspissated albumen. Yolk material was occasionally found in the abdominal cavity and there was one instance of egg peritonitis. Eggs with abnormal shells were found in the uterus on days 3 and 9. By direct immunofluorescence (IF) staining, virus was detected in the trachea between days 1 and 7 pi and in the turbinâtes between days 2 and 5 pi. Virus could also be isolated from these sites using turkey embryo trachéal organ cultures but this method was slightly less sensitive than IF for these tissues. No virus was demonstrated in the lungs or air sacs. Viral antigens were detected by IF in the epithelium of the uterus on day 7 pi and in this and all other regions of the oviduct on day 9 pi. Virus was isolated only from middle magnum and vagina on day 9 pi. On other occasions up to 20 days pi the above tissues and spleen, ovary, liver, kidney and hypothalamus were all negative for virus. Antibodies detected by ELISA and serum neutralisation both reached, high titre by 12 days pi and were maintained at a high level (Iog2 12-15) throughout the period of observation (89 days).

No abstract

No abstract

No abstract

Factors affecting production of Large White turkey hens were examined. Six flocks (n = 136 to 149 hens per flock) were housed at commercial facilities in the United States and two flocks (n = 40 hens per flock) were housed at commercial facilities in the United Kingdom (UK). Effects of time-in-lay on egg production and duration of clutches and pauses were determined using all flocks. Also, effects of time-in-lay, molt, and characteristics of individual eggs (size, sequence position, grade, and incubational weight loss) on fertility, hatchability, and embryonic mortality were determined using the UK flocks. Each flock showed a distinctive pattern of production; it increased initially to a peak and decreased thereafter. Average duration of clutches and of pauses were correlated positively and negatively, respectively, with hen-day egg production. As production declined toward the latter half of lay, a greater proportion of short clutches and, therefore, of first-of-clutch eggs were laid. During the course of the first cycle of lay, eggs became larger and a greater proportion were of low grade. Fertility and hatchability increased initially then decreased. Effects of time-in-lay differed after a forced molt. Egg size changed only slightly with time in the second cycle, and fertility and hatchability were greater in the second cycle than in the first cycle. In both cycles, sequence position affected grade (first-of-sequence eggs were of lower grade compared with eggs laid subsequently), and grade influenced percentage weight loss, fertility, hatchability, and embryonic mortality. The results of this study support selection of hens based on duration of clutches. In addition, the single most significant preincubational variable for predicting hatchability was grade of the egg. (