Tolerance capability of desert sheep and goats to exercise heat stress under hot dry conditions, and its correlation with their production performance

The study aims to investigate tolerance capability of desert Barki sheep and goats exercise heat stress (EHS) under the hot-dry conditions Coastal Zone Western Desert, in Egypt. Over period from 2009 2014, mature ewes does were exposed (EHS); walking for 7 km July August 12 noon 3 pm (simulating summer grazing on poor pasture). Physiological parameters: rectal temperature (RT), skin (ST), respiratory rate (RR) gas volume (GV) measured at rest, by 7am, directly after exposure. Tidal (TV) metabolic (MR) further calculated. Exposing EHS, raised significantly (P ≤ 0.01) their physiological parameters (RT, ST, RR, GV), decreasing MR TV. main thermoregulatory mechanism tolerate was increase loss (increase RR GV). While, relied mainly rapid shallow painting, besides reducing production. showed better physical hot dry than sheep. Individual variation, cause variability changes studied with followed year species variation. Changes EHS positively 0.05) correlated body weight exposure, insignificantly yearling weaning weights. Light lambs kids are less tolerant stress. While heavy animals yearling, especially goats, have difficulty long distance Medium size relatively sheep, seems be more compatible conditions, either light or performed animals. For breeding purpose, there is room selection goat environmental stress, together production traits.