Effect of acute heat exposure on blood flow and its distribution in the unrestrained laying fowl (Gallus domesticus)

Abstract

1. The effect of heat exposure (air temperature 35-45°C) for 1.5 h on blood flow distribution between the abdominal viscera and the muscles of abdominal wall and hind leg was investigated in unanaesthetised, unrestrained laying fowl. 2. Heat stressed fowl showed a significant hyperthermia (+ 1.3°C), rapid shallow breathing (229 breaths/min) and significant hypocapnia ( -8 Torr). 3. Significant increases in absolute blood flow (ml/g per min) were measured in the kidneys, spleen, liver and duodenum during hyperthermia, but there was no change in the absolute blood flow to the reproductive tract or the relative perfusion of the reproductive tract compared with the other tissues sampled. 4. We conclude that in these acute conditions of heat exposure, blood flow to the reproductive tract of the laying fowl is not compromised by any simultaneous thermoregulatory needs.

Response of Commercial Layers to Housing at Different Cage Densities and Heat Stress Conditions. 1- Physiological Indicators and Immune Response

“…16). These results are in agreement with the findings of Arad et al (1993) and Usayran et al (2001). They reported that, high environmental temperatures significantly decreased the serum or plasma calcium concentrations.…”

Physiological parameter values for physiologically based pharmacokinetic models in food‐producing animals. Part II: Chicken and turkey

“…Regional blood flow values were identified in six studies with a total of 41 animals (Arad et al., 1993 ; Boelkins et al., 1973 ; Merrill et al., 1981 ; Sapirstein & Hartman, 1959 ; Wolfenson et al., 1978 , 1981 ), including the proventriculus, gizzard, and all parts of small intestine and colon (Tables 15 and 16 ). Values for the crop, ceca, or cloaca were not found.…”

“…From five studies in chickens with 49 animal subjects (Arad et al., 1993 ; Boelkins et al., 1973 ; Merrill et al., 1981 ; Wolfenson et al., 1978 , 1981 ), we calculated the mean value of relative blood flow to pancreas to be 0.066 L hr −1 kg −1 BW which pertains 0.67% of cardiac output (Tables 15 and 16 ). Values for pancreatic regional blood flow were not reported for mice, rats, dogs, or humans in Brown et al.…”

Environmental Heat Stress Does Not Reduce Blood Ionized Calcium Concentration in Hens Acclimated to Elevated Temperatures

“…Eggs from hens at HI vs LO had lower (P < 0.05) average weight (64.9 ± 0.87 g vs 68.1 + 0.96 g) and lower (P < 0.05) specific gravity (1.079 ± 0.0008 vs 1.084 + 0.0009). De Andrade et al (1977) suggested that blood flow redistribution may be one factor responsible for the low eggshell quality under heat stress conditions; however, this assumption has recently been contradicted by Arad et al (1993), who reported that blood flow to the reproductive tract of the laying hen was not reduced during exposure to temperature of 35 to 45 C for 1.5 h. If this is the case, calcium supply to the shell gland may not change during shell deposition; therefore, it seems more probable that other physiological changes such as reduced calcium secretion (Bragg et al, 1971), reduced calcium transport in the shell gland (Odom and Harrison, 1985), or a drop in the amount of bicarbonate ions caused by respiratory alkalosis are the major factors contributing to the reduction in shell quality under high temperature conditions. Other studies suggest that the production of H+ ions in the shell gland during shell formation facilitates the dissociation of the calciumprotein complex (Winget and Smith, 1962;Hodges, 1969), which in turn makes calcium available for shell deposition in the form of calcium carbonate.…”