Alleviative effects ofα-lipoic acid supplementation on acute heat stress-induced thermal panting and the level of plasma nonesterified fatty acids in hypothyroid broiler chickens

Abstract

1. The present study was conducted to examine the effects of α-lipoic acid on hypothyroidism-induced negative growth performance and whether α-lipoic acid alleviates acute heat stress in relation to hypothyroid status. 2. Female broiler chickens (14 d-old) were fed diets supplemented with α-lipoic acid (100 mg/kg) and an antithyroid substance, propylthiouracil (200 mg/kg), for 20 d under thermoneutral conditions (25°C). At 42 d of age, chickens were exposed to a high ambient temperature (36°C, 60% RH) for 4 h. 3. Under the thermoneutral condition, propylthiouracil administration decreased feed efficiency and concomitantly increased adipose tissue and thyroid gland weights. Plasma nonesterified fatty acids and triacylglycerol were also increased by propylthiouracil administration. However, α-lipoic acid supplementation did not affect the hypothyroidism-induced effects. 4. In hypothyroid chickens, the rise in respiratory rate induced by heat exposure was greatly inhibited by α-lipoic acid administration at 1 h, but this effect had disappeared at 4 h. In addition, a similar inhibitory effect on the concentrations of plasma nonesterified fatty acids was subsequently observed at 4 h. 5. Therefore, the present study suggested that α-lipoic acid alleviates acute heat stress if chickens are in a hypothyroid status.

Supplementation of Bacillus subtilis-based probiotic reduces heat stress-related behaviors and inflammatory response in broiler chickens1

“…In the current study, broilers exposed to high temperatures had high levels of natural antibodies, antibodies without any previous antigen exposure, in the cecal tonsils as a response to heat-stimulated intestinal inflammation. Similar to these findings, previous studies have shown that HS induce local inflammation, resulting in intestinal microstructural injury and pathogenic infection (Quinteiro-Filho et al, 2010, 2012, leading to high natural antibodies (Regnier et al, 1980;Strong et al, 2015). These HS effects were reduced in the HS-PD birds which had lower levels of both IgA and IgY compared to HS-RD.…”

“…As the ambient temperature increases beyond the TNZ, chickens alter their behaviors to prevent body core temperature changes; so, the temperature modulation is shifted from sensible heat loss (such as radiation via the wattle, comb, feet, and wing spreading) to evaporative heat loss (such as panting) (Lustick, 1983). However, excessive panting decreases the partial pressure of carbon dioxide and calcium availability, while increases pH value in blood, leading to the risk of respiratory alkalosis (Hamano, 2012) and lameness (Hothersall et al, 2014). Recent studies have shown that gut microbiota are able to alleviate inflammatory response and reduce stress-induced behaviors in humans and rodents via regulation of both the microbiota-gut-brain axis (Yano et al, 2015) and the microbiota-gut-immunity axis (Brandsma et al, 2015).…”

Nutritional Interventions to Alleviate the Negative Consequences of Heat Stress

“…Oral lipoic acid supplementation in poultry decreased plasma glucose and increased whole-body insulin sensitivity while increasing plasma triglycerides and adipose tissue lipolysis (159,160). However, the effectiveness of lipoic acid supplementation to alter glucose availability may be dependent on the magnitude and duration of heatstress events (161). Similar to chickens, oral lipoic acid supplementation reduced plasma glucose concentrations in young swine maintained in thermoneutral conditions (162).…”

An Acute, Rather Than Progressive, Increase in Temperature-Humidity Index Has Severe Effects on Mortality in Laying Hens

“…However, panting was observed at 38 • C with an increased rectal temperature and moderate alkalosis (pH 7.58), and further panting was observed at 41 • C with severe alkalosis (pH 7.65) and considerably high rectal temperature. Respiratory rates increased from 74 at 0 h, 218 at 1 h, and to 207 at 4 h in 42-day-old broilers kept at an ambient condition of 36 • C and 60% relative humidity (33). Similar findings were reported in egg-laying ducks exposed to chronic heat stress, which led to increases in panting rates and spreading of wings and reduction in feed intake, laying rates and egg quality, including egg weight, eggshell thickness and strength, and Haugh unit (34).…”