Modeling energy requirement for layer-type chicks reared at different ambient temperatures

Area of Science:

• Animal Science
• Poultry Nutrition
• Environmental Physiology

Background:

• Precision feeding in poultry requires accurate nutrient requirement estimations.
• Rearing temperature significantly influences poultry physiological stages and energy demands.

Purpose of the Study:

• To determine the effect of rearing temperature on the net energy (NE) requirement of Jingfen layer-type chicks from 1 to 14 days of age.
• To establish a formula for calculating the NE requirement based on environmental temperature and body weight gain.

Main Methods:

• Trial 1: Measured energy requirement for maintenance (MEm) using indirect calorimetry (oxygen consumption and CO2 production) at five different temperatures (30-38°C).
• Trial 2: Assessed growth performance (body weight gain, feed intake, feed conversion ratio) and body composition under varying temperature regimens.
• Utilized Jingfen layer-type chicks, with sample sizes of 160 for MEm and 480 for growth performance studies.

Main Results:

• Fasting heat production (FHP) decreased significantly with increasing temperature (P < 0.001).
• Body weight gain and feed intake decreased as temperature rose (P < 0.001), while feed conversion ratio was affected only in the first week (P < 0.01).
• Relative organ weights (heart, liver, breast muscle) decreased with higher temperatures; however, the net energy requirement for body weight gain was not significantly altered by temperature (P > 0.05).

Conclusions:

• Rearing temperature influences energy metabolism and growth performance in young chicks.
• The net energy requirement for body weight gain in Jingfen layer-type chicks aged 1-14 days is independent of rearing temperature.
• A specific formula was derived to calculate the NE requirement: NE (kJ/bird·day⁻¹) = (505.93 - 162.78T - 38.87T² + 194.41T³)·kgW⁰·⁷⁵ + 7.16·BW gain (g/d).