Genetic control of disease resistance between and within sheep breeds

This study was conducted to indicate the association among blood potassium with some physiological traits of Iraqi sheep breeds, its in-cluded198Awasi , 40 Arabi and 59 Karadi sheep besides fecal egg count for internal parasite were calculated. Blood potassium estimated by using of atomic absorption flame photometer. The results revealed the fallowing :1- Potassium level of Awssi, Arabi and Karadi sheep blood showed a bimodal distribution , the low potassium (LK) and the high potassium (HK) . 2-Arabi sheep recorded significantly more FEC than that in Awasi and Karradi in which 7410, 4313 and 3519 egg/feces respectively .3- Karadi (LK) sheep showed significantly higher FEC than that in LK Karradi sheep in which recorded 6360 and 3255 egg/feces respectively. Generally this study proved that the FEC increase in the Ewes com-paring with Rams in all different breeds, Although without getting a significant differences, the reason for such results because the females undergoing through a period of her life go through different stages of physiological condition such as pregnancy and births, which increasingly influential in the effort to increase the intensity of infection. Older animalshave lower FEC than younger animals, and the young sheep have less resistance to infection compared with the old sheep, as well as the case for females sheep in which they have less resistance when comparing with male sheep.