The Effect of High Ambient Temperature and Hypercapnia on Postprandial Intestinal Hyperemia in Domestic Cockerels

Abstract

Hubbard cockerels (2.8 to 3.6 kg) with chronically implanted electromagnetic blood flow probes placed on the celiac artery were used to determine the effect of elevated ambient temperature on postprandial intestinal hyperemia. Celiac mean blood flow (MBF) increased (P less than .05) from approximately 25 to 50 ml/min in response to feeding. When a thermoneutral temperature of 25 C was maintained, celiac MBF remained above 40 ml/min up to 210 min but fell below 25 ml/min by 300 min postprandial. In response to an acute heat exposure of 37 C, postprandial celiac MBF was reduced by approximately 50% in comparison to thermoneutral control values. Changes in celiac MBF during heat exposure were significantly (P less than .05) correlated (.60) with blood CO2 partial pressure (PCO2). To determine if flood PCO2 affected postprandial celiac MBF, cockerels were subjected to successive elevated ambient temperature and ambient CO2 treatments. Although cockerels exposed to 2.8% CO2 exhibited an increase in blood PCO2 regardless of temperature treatment, postprandial celiac MBF changes in these ambient CO2 experiments were only moderately correlated (P less than .05) with blood PCO2 (.34) but inversely correlated (-.83) with celiac vascular resistance (P less than .001). This study indicates that acute heat exposure reduces postprandial intestinal hyperemia and that this hemodynamic alteration was coincident with, but not necessarily dependent upon, changes in blood PCO2.

Dietary levels of potassium for broiler chickens

“…The observed levels were 104% and 138% higher than those recommended by NRC for this phase, i.e., 0.35 and 0.30% of K (NRC, 1984 and1994, respectively). Environmental temperature was very close to the threshold of thermal comfort (Table 2), which could increase K requirements due to poorer intestinal blood irrigation (Bottje & Harrison, 1986;Wolfenson et al, 1987). As observed in the first experiment, there was no significant difference for FCR.…”

Alpha Adrenergic Regulation of Celiac Blood Flow and Plasma Catecholamine Response During Acute Heat Stress in Fed Cockerels

“…Four cockerels were prepared with an electromagnetic blood flow probe (Carolina Medical Electronics, King NC) and vascular occluder on the celiac artery as previously described, (Bottje and Harrison, 1986). Following surgery, the birds were fitted with a chest movement transducer (Model T-4013; Gilson Medical Electronics, Middleton, WI) and a rectal probe (Yellow Springs Instruments, Yellow Springs, OH) and placed in an environmentally controlled chamber (Model 118L, Conviron, Controlled Environments, Pembina, ND) maintained at 25 C. The birds were adapted to instrumentation for a minimum of 3 days before experimentation.…”

“…Postprandial intestinal hyperemia was reduced by a hot environmental temperatureinduced increase in intestinal vascular resistance (Bottje and Harrison, 1986). Although inhibitory sympathetic innervation of domestic fowl mesenteric arteries has been identified (Bolton, 1968;Bell, 1969), studies have not been conducted to determine the a-adrenergic involvement of visceral blood flow responses to feeding and elevated ambient temperature in intact conscious fowl.…”