Effect of Heat Exposure on Gene Expression of Feed Intake Regulatory Peptides in Laying Hens

The aim of this paper was to investigate the effect of heat stress on the regulation of appetite-associated genes in laying hens. Forty eight laying hens were randomly divided into two circumstances: high (31 ± 1.5°C; relative humidity, 82.0 ± 2.2%) or normal (20 ± 2°C, control; relative humidity, 60.1 ± 4.5%) ambient environment. Heat stress decreased body weight gain (<svg style="vertical-align:-0.30096pt;width:56.150002px;" id="M1" height="11.0625" version="1.1" viewBox="0 0 56.150002 11.0625" width="56.150002" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,11.0625)"> <g transform="translate(72,-63.15)"> <text transform="matrix(1,0,0,-1,-71.95,63.5)"> <tspan style="font-size: 12.50px; " x="0" y="0">𝑃</tspan> <tspan style="font-size: 12.50px; " x="10.890113" y="0"><</tspan> <tspan style="font-size: 12.50px; " x="22.930502" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="29.182001" y="0">.</tspan> <tspan style="font-size: 12.50px; " x="32.307751" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="38.559254" y="0">1</tspan> </text> </g> </g> </svg>), feed intake (<svg style="vertical-align:-0.30096pt;width:56.150002px;" id="M2" height="11.0625" version="1.1" viewBox="0 0 56.150002 11.0625" width="56.150002" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,11.0625)"> <g transform="translate(72,-63.15)"> <text transform="matrix(1,0,0,-1,-71.95,63.5)"> <tspan style="font-size: 12.50px; " x="0" y="0">𝑃</tspan> <tspan style="font-size: 12.50px; " x="10.890113" y="0"><</tspan> <tspan style="font-size: 12.50px; " x="22.930502" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="29.182001" y="0">.</tspan> <tspan style="font-size: 12.50px; " x="32.307751" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="38.559254" y="0">1</tspan> </text> </g> </g> </svg>), laying rate (<svg style="vertical-align:-0.30096pt;width:56.150002px;" id="M3" height="11.25" version="1.1" viewBox="0 0 56.150002 11.25" width="56.150002" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,11.25)"> <g transform="translate(72,-63)"> <text transform="matrix(1,0,0,-1,-71.95,63.35)"> <tspan style="font-size: 12.50px; " x="0" y="0">𝑃</tspan> <tspan style="font-size: 12.50px; " x="10.890113" y="0"><</tspan> <tspan style="font-size: 12.50px; " x="22.930502" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="29.182001" y="0">.</tspan> <tspan style="font-size: 12.50px; " x="32.307751" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="38.559254" y="0">5</tspan> </text> </g> </g> </svg>), average egg mass (<svg style="vertical-align:-0.30096pt;width:56.150002px;" id="M4" height="11.0625" version="1.1" viewBox="0 0 56.150002 11.0625" width="56.150002" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,11.0625)"> <g transform="translate(72,-63.15)"> <text transform="matrix(1,0,0,-1,-71.95,63.5)"> <tspan style="font-size: 12.50px; " x="0" y="0">𝑃</tspan> <tspan style="font-size: 12.50px; " x="10.890113" y="0"><</tspan> <tspan style="font-size: 12.50px; " x="22.930502" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="29.182001" y="0">.</tspan> <tspan style="font-size: 12.50px; " x="32.307751" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="38.559254" y="0">1</tspan> </text> </g> </g> </svg>), egg production (<svg style="vertical-align:-0.30096pt;width:56.150002px;" id="M5" height="11.0625" version="1.1" viewBox="0 0 56.150002 11.0625" width="56.150002" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,11.0625)"> <g transform="translate(72,-63.15)"> <text transform="matrix(1,0,0,-1,-71.95,63.5)"> <tspan style="font-size: 12.50px; " x="0" y="0">𝑃</tspan> <tspan style="font-size: 12.50px; " x="10.890113" y="0"><</tspan> <tspan style="font-size: 12.50px; " x="22.930502" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="29.182001" y="0">.</tspan> <tspan style="font-size: 12.50px; " x="32.307751" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="38.559254" y="0">1</tspan> </text> </g> </g> </svg>), shell thickness (<svg style="vertical-align:-0.30096pt;width:56.150002px;" id="M6" height="11.0625" version="1.1" viewBox="0 0 56.150002 11.0625" width="56.150002" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,11.0625)"> <g transform="translate(72,-63.15)"> <text transform="matrix(1,0,0,-1,-71.95,63.5)"> <tspan style="font-size: 12.50px; " x="0" y="0">𝑃</tspan> <tspan style="font-size: 12.50px; " x="10.890113" y="0"><</tspan> <tspan style="font-size: 12.50px; " x="22.930502" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="29.182001" y="0">.</tspan> <tspan style="font-size: 12.50px; " x="32.307751" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="38.559254" y="0">1</tspan> </text> </g> </g> </svg>), and feed efficiency (<svg style="vertical-align:-0.30096pt;width:56.150002px;" id="M7" height="11.25" version="1.1" viewBox="0 0 56.150002 11.25" width="56.150002" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,11.25)"> <g transform="translate(72,-63)"> <text transform="matrix(1,0,0,-1,-71.95,63.35)"> <tspan style="font-size: 12.50px; " x="0" y="0">𝑃</tspan> <tspan style="font-size: 12.50px; " x="10.890113" y="0"><</tspan> <tspan style="font-size: 12.50px; " x="22.930502" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="29.182001" y="0">.</tspan> <tspan style="font-size: 12.50px; " x="32.307751" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="38.559254" y="0">5</tspan> </text> </g> </g> </svg>). High ambient temperature decreased plasma uric acid (<svg style="vertical-align:-0.30096pt;width:56.150002px;" id="M8" height="11.25" version="1.1" viewBox="0 0 56.150002 11.25" width="56.150002" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,11.25)"> <g transform="translate(72,-63)"> <text transform="matrix(1,0,0,-1,-71.95,63.35)"> <tspan style="font-size: 12.50px; " x="0" y="0">𝑃</tspan> <tspan style="font-size: 12.50px; " x="10.890113" y="0"><</tspan> <tspan style="font-size: 12.50px; " x="22.930502" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="29.182001" y="0">.</tspan> <tspan style="font-size: 12.50px; " x="32.307751" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="38.559254" y="0">5</tspan> </text> </g> </g> </svg>). Heat stress significantly increased mRNA levels of ghrelin and cocaine- and amphetamine-regulated transcript (<svg style="vertical-align:-0.30096pt;width:56.150002px;" id="M9" height="11.25" version="1.1" viewBox="0 0 56.150002 11.25" width="56.150002" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,11.25)"> <g transform="translate(72,-63)"> <text transform="matrix(1,0,0,-1,-71.95,63.35)"> <tspan style="font-size: 12.50px; " x="0" y="0">𝑃</tspan> <tspan style="font-size: 12.50px; " x="10.890113" y="0"><</tspan> <tspan style="font-size: 12.50px; " x="22.930502" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="29.182001" y="0">.</tspan> <tspan style="font-size: 12.50px; " x="32.307751" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="38.559254" y="0">5</tspan> </text> </g> </g> </svg>) and decreased mRNA levels of cholecystokinin (<svg style="vertical-align:-0.30096pt;width:56.150002px;" id="M10" height="11.25" version="1.1" viewBox="0 0 56.150002 11.25" width="56.150002" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,11.25)"> <g transform="translate(72,-63)"> <text transform="matrix(1,0,0,-1,-71.95,63.35)"> <tspan style="font-size: 12.50px; " x="0" y="0">𝑃</tspan> <tspan style="font-size: 12.50px; " x="10.890113" y="0"><</tspan> <tspan style="font-size: 12.50px; " x="22.930502" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="29.182001" y="0">.</tspan> <tspan style="font-size: 12.50px; " x="32.307751" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="38.559254" y="0">5</tspan> </text> </g> </g> </svg>) in the hypothalamus. Heat stress significantly increased (<svg style="vertical-align:-0.30096pt;width:56.150002px;" id="M11" height="11.25" version="1.1" viewBox="0 0 56.150002 11.25" width="56.150002" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,11.25)"> <g transform="translate(72,-63)"> <text transform="matrix(1,0,0,-1,-71.95,63.35)"> <tspan style="font-size: 12.50px; " x="0" y="0">𝑃</tspan> <tspan style="font-size: 12.50px; " x="10.890113" y="0"><</tspan> <tspan style="font-size: 12.50px; " x="22.930502" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="29.182001" y="0">.</tspan> <tspan style="font-size: 12.50px; " x="32.307751" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="38.559254" y="0">5</tspan> </text> </g> </g> </svg>) mRNA levels of ghrelin in the glandular stomach and jejunum but significantly decreased (<svg style="vertical-align:-0.30096pt;width:56.150002px;" id="M12" height="11.25" version="1.1" viewBox="0 0 56.150002 11.25" width="56.150002" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,11.25)"> <g transform="translate(72,-63)"> <text transform="matrix(1,0,0,-1,-71.95,63.35)"> <tspan style="font-size: 12.50px; " x="0" y="0">𝑃</tspan> <tspan style="font-size: 12.50px; " x="10.890113" y="0"><</tspan> <tspan style="font-size: 12.50px; " x="22.930502" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="29.182001" y="0">.</tspan> <tspan style="font-size: 12.50px; " x="32.307751" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="38.559254" y="0">5</tspan> </text> </g> </g> </svg>) mRNA levels of cholecystokinin in the duodenum and jejunum. In conclusion, heat stress plays a unique role in some special neuropeptides (e.g., ghrelin, cocaine- and amphetamine-regulated transcript, and cholecystokinin), which might participate in the regulation of feed intake in laying hens under high ambient temperature.