'Clustering'--real or apparent? Probability maps of childhood cancer in the West Midlands Health Authority region.

The West Midlands Regional Children's Tumour Registry collects detailed information on all cases of childhood cancer in the West Midlands Health Authority Region (WMHAR). The distribution by electoral ward of all cases diagnosed in the WMHAR between 1980 and 1984 has been determined. Analysis has also been performed for leukaemias/non-Hodgkin's lymphomas alone. We suggest that this latter grouping should be universally employed, owing to the difficulty of accurately separating out cases of leukaemia. Both spatial analyses showed several wards with significantly excessive rates on the basis of their cumulative Poison probability. Observed/expected ratios of 3-35 were seen for cases in significant wards, which are similar to the ratios seen in analysis of incidence around nuclear installations. However, further detailed consideration of these individual significance levels in the light of the number of statistically significant wards which would occur by chance alone, due to the multiple use of the test, accounted completely for the number of wards obtained in each of the groups considered. Thus, apparent 'clustering' of cases could be mere statistical artefact. In the WMHAR, therefore, using the technique of probability mapping, no true spatial pattern of incidence was found, other than that which would occur by chance alone. This, in a large area without nuclear installations and an even mix of rural and industrialised regions, could be seen as control data for those studies which have considered cases of childhood leukaemia around nuclear facilities, where the observation of single point clusters associated with suspected sites restricts assessments of spatial pattern in the rest of the area.(ABSTRACT TRUNCATED AT 250 WORDS)

Restricted feeding of broiler breeders.

Two experiments were conducted to compare the effects of various feed restriction programs during the growing and laying periods on body weight, egg production, fertility, and hatchability. In the first experiment, Cobb color-sexed broiler breeders were fed one of three grower programs (full feed, skip-a-day, or low protein) from 8 to 24 weeks of age. Two layer programs (full feed and restricted) were fed from 24 to 67 weeks of age. Overall the skip-a-day grower treatment gave the best results of the programs tested. This treatment resulted in the significantly lowest body weights, greatest delay in sexual maturity, and highest egg production and fertility. The restricted layer treatment resulted in lower body weight, delayed sexual maturity, lower egg production during the colder months, and higher fertility and hatchability of fertile eggs. In the second experiment, Cobb color-sexed broiler breeders were fed one of three skip-a-day grower treatments (control or breeder's recommendations, control minus 10%, control minus 20%) from 8 to 24 weeks of age. Two layer programs (full feed and restricted) were fed from 24 to 51 weeks of age. Overall, the control minus 20% treatment resulted in significantly delayed sexual maturity and significantly decreased body weight. The restricted layer treatment also significantly delayed sexual maturity and decreased body weight.

Lighting of end of lay broiler breeders: fluorescent versus incandescent.

An 18-week experiment was conducted to investigate the effects of changing from incandescent to fluorescent lighting on egg production, egg weight, fertility, and hatchability of end of lay broiler breeders housed in an open-sided house. Forty-eight-week-old Cobb feather-sexed broiler breeders were housed, 30 females and 3 males per pen, in a total of 28 pens. Incandescent lights had been used previously, so pens were randomly assigned to either fluorescent or incandescent lights giving 20 lx of light at bird level. Lights used were 60 W incandescent and 22 W fluorescent cool-white circular. Body weight and egg production were measured weekly, and fertility, hatchability, and egg weight were determined monthly from 48 to 65 weeks of age. No significant treatment effects were observed on body weight, fertility, hatchability, or egg weight. A significant reduction in egg production was observed with fluorescent lighting from Weeks 58 to 65. The reduced egg production indicated it was detrimental to change from incandescent to cool-white fluorescent lighting.

Effect of daily restriction and age at initiation of a skip-a-day program for young broiler breeders.

Two experiments were conducted with Cobb feather sex broiler breeders comparing skip-a-day (SAD) feeding programs which began at either 2, 4, 6 or 8 wk of age. A fifth program, daily restriction started at 2 wk of age, was also compared. Chicks hatched in December and July, respectively, in Experiments 1 and 2 were exposed to natural daylight until 20 wk of age. All birds were fed ad libitum until the respective restriction programs began. All grower programs terminated at 20 wk of age. A breeder diet was given daily after 20 wk. Males and females were grown together. Sexual maturity was reached earlier in the 2-wk restriction groups (2-wi SAD in Experiment 1 and the 2-wk daily restriction in both experiments) than in the 8-wk SAD group. Egg production in Experiment 1 was also improved by the early restriction. Fertility and hatchability were not significantly affected by treatment. Based on the results of these experiments a SAD program beginning at 2 wk of age was as good as or better than one initiated at later ages. The 2-wk daily restriction program was equivalent to the 2-wk SAD program.

Interactive effects of sodium bentonite and coccidiosis with monensin or salinomycin in chicks.

Three experiments (Exp.) were conducted to determine the interactive effects of sodium bentonite (NaB) with the efficacy of monensin (MON) or salinomycin (SAL) in coccidiosis-infected chicks. Male broiler chicks 5 to 14 d of age were used, and each treatment was replicated with eight (Exp. 1) or four (Exp. 2 and 3) pens of five chicks each. In Exp. 1, MON (80 ppm), NaB (0.50%), or MON+NaB were fed to uninfected and coccidiosis-infected (5 x 10(5) sporulated Eimeria acervulina oocysts on Day 2 of the Exp.) chicks in a 2 x 2 x 2 factorial arrangement of treatments. Experiment 2 was identical to Exp. 1, but SAL (30 ppm) replaced MON as the anticoccidial additive. In Exp. 3, MON (55 ppm) or SAL (22 ppm) were added individually or with NaB (0.50%) to diets for uninfected or coccidiosis-infected chicks. Coccidial infection reduced (P < 0.01) gain, feed intake, gain:feed, plasma carotenoids, and percentage tibia ash in all experiments. The MON and SAL additions increased these response criteria in infected chicks (coccidiosis by anticoccidial, P < 0.07), except MON did not increase (P > 0.10) feed intake or tibia ash in Exp. 3. In Exp. 3, NaB partially reduced the positive effect of MON on daily gain (NaB by MON, P < 0.03), and of SAL on feed intake (NaB by SAL, P < 0.08). The NaB addition also increased gain:feed (P < 0.08), and the increase was greater in infected chicks (coccidiosis by NaB, P < 0.08). Also in Exp. 3, SAL increased feed intake more in chicks not fed NaB than in chicks fed NaB (SAL by NaB, P < 0.08). Dietary NaB (0.5%) may reduce the efficacy of MON and SAL in coccidiosis-infected chicks when these additives are added at less than recommended levels.

The performance of Bobwhite quail fed diets containing Lactobacilli.

Two experiments were conducted each consisting of two trials. Day-old Bobwhite quail were fed a starter diet containing a microbial preparation of Lactobacilli. In both experiments the experimental diets were fed for 5 weeks. No significant differences in growth, feed efficiency, or mortality were found between the control and Lactobacilli supplemented diets. Mortality was higher than normal within all treatments but unaffected by treatment.

Hatchability of bobwhite quail eggs incubated in various temperature combinations.

Five experiments were conducted to compare the effects of various incubation temperature combinations on the hatchability of Bobwhite quail eggs. A starting incubation temperature of 40.6 C resulted in numerically lower hatchability. Incubation at 37.5 C resulted in a greater number of pipped, unhatched eggs, and a later, less uniform hatch. Temperatures during the hatching period (22 to 25 days of incubation) of 36.9 C and 38.1 C resulted in lower hatchability than the hatching temperature of 37.5 C.

Migration and population change within metropolitan Toronto, 1966-1971.

PIP: Vital registration data for the 6 municipalities of metropolitan Toronto and data collected by Statistics Canada relating to the size of the population in 1966 and 1971 and the number and origins of recent in-migrants in 1971 were examined in an effort to determine the importance of various sources of population change within metropolitan Toronto and to assess the effects of immigration on the size and distribution of the population. It was found that while net natural increase accounted for slightly more than half of the overall growth, the redistribution of the 1966 population and the addition of people from outside the metropolitan area were more important for understanding spatial variations in population change. Longer term residents tended to move away from the inner municipalities but the pattern of a suburbanizing population had been obscured by the tendency of recent immigrants to reside in the inner areas. For example, 62% of the 1966-1971 immigrants to the area resided in 3 inner municipalities in 1971. Had there been no immigrants, the decline in population in the municipalities registered between 1966-1971 would have been even greater.^ieng