The effects of cooling large white turkey embryos on growth and white blood cell development

In each of two experiments, trays containing 15 developing turkey eggs were cooled for 1 h at 18 C on a specific day of incubation or left within the incubator (controls). Ten embryos from each treatment were bled on Day 23 of incubation, at which time all embryos were killed with CO2 gas, weighed, and sexed. Packed cell volumes and differential white blood cell (WBC) counts were performed on all blood samples. A single, brief cooling episode during incubation did not significantly (P greater than .05) affect BW or hematocrit values in 23-day-old turkey embryos. Based on a differential classification of WBC in the blood smears of these turkey embryos, there were 82, 10, 8, less than 1, and less than 1% of heterophils, lymphocytes, basophils, eosinophils, and monocytes, respectively. Circulating heterophils, the most numerous WBC in turkey embryos, were significantly (P less than or equal to .05) reduced in all embryos cooled during the latter half of incubation. This effect was mirrored in the total WBC numbers counted. The effect of cooling on the other classes of turkey embryonic WBC, which represent about 20% of the circulating WBC, were more variable.