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An experiment was conducted to determine the effect of a micromist, high pressure, evaporative cooling and dust control system on rearing environment characteristics and performance of broiler chickens. Air of rearing chambers with the cooling and dust control system had significantly lower dust concentrations than that of chambers without the system. Birds reared with the cooling and dust control system were 45 and 165 g heavier at 4 and 7 wk of age, respectively, and had significantly higher 7-wk bursa weights than those reared without the system. Presence of the cooling and dust control system had no effect on mortality or lung weights.

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Two trials were conducted to study the effects of high dietary Zn on tissue Zn accumulation and depletion in laying hens. Hens laying at approximately 60 to 70% were fed a diet containing 20 g Zn as ZnO/kg diet (as fed) for 4 days. For the remaining 18 days, hens were fed the same diet without the 20 g added Zn/kg diet. Ten hens were killed at initiation of the experiment (Day 0), and liver, kidney, and pancreas were obtained for Zn analysis. On Days 1, 2, 3, 4, 10, 16, and 22, similar samples were obtained from 10 hens. Feeding high Zn for 4 days caused a reduction in ovary and oviduct weight by Day 10. Liver, kidney and pancreas Zn concentrations increased approximately 10, 3, and 25-fold, respectively, in birds following 4 days of feeding the high Zn diets. The liver and kidney Zn concentrations returned to pretreatment concentrations within 18 days after the birds were fed the control diets (Day 22). The pancreas maintained higher Zn concentrations in comparison with the other tissues following withdrawal of the high Zn diet.

Three experiments were conducted to evaluate the use of poultry fat (PF) or yellow grease (YG) when fed to broilers. Experiments 1 and 2 were duplicate, 21-day studies, and Experiment 3 compared the fats over a 42-day period. Treatments for Experiments 1 and 2 consisted of six replicates of eight battery-housed chicks that were fed 5% added fat as all PF, all YG, or PF: YG blends of 90:10, 80:20, 70:30, 60:40, or 50:50. In Experiment 3, five replicate pens of 70 day-old broiler chicks were floor-reared and fed either all PF, all YG, or a 50:50 blend in diets containing 3.0 and 3.5% added fat in starter and finisher diets, respectively. Factored across fat source were two different fat stabilization times: 1) fresh from the rendering plant; and 2) held under feed mill conditions for 7 days.All fat combinations performed comparably in terms of body weight, feed intake, feed conversion, and mortality rate. Fatty acid content and fat quality factors, including 20-h active oxygen method (AOM) determinations, were similar among fat sources. In Experiment 3, no differences were found due to stabilization time. Return over feed cost was not affected by any of the fat and stabilization time treatment combinations. No association was found between bird performance and AOM, suggesting that a better analytical procedure of fat quality was warranted. At levels tested, YG and PF-YG blends were found to be as suitable a feed fat source as PF.(