Earlier Metabolizable Energy Intake Level Influences Heat Production during a Following 3-Day Fast in Laying Hens.

Ning Dong ,Yuming Guo ,Y.w Wang ,Yutao Peng

doi:10.5713/ajas.2012.12566

Ning Dong , Yuming Guo + Show 2 more

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https://doi.org/10.5713/ajas.2012.12566

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Abstract

The present study was conducted to estimate energy requirements for maintenance in laying hens by using indirect calorimetry and energy balance. A total of 576 28-wk-old Nongda-3 laying hens with dwarf gene were randomly allocated into four ME intake levels (86.57, 124.45, 166.63 and 197.20 kcal/kg body weight (BW)0.75 per d) with four replicates each. After a 4 d adaptation period, 36 hens from one replicate were maintained in one of the two respiration chambers to measure the heat production (HP) for 3 d during the feeding period and subsequent 3 d fast. Metabolizable energy (ME) intake was partitioned between heat increment (HI), HP associated with activity, fasting HP (FHP) and retained energy (RE). The equilibrium FHP may provide an estimate of NE requirements for maintenance (NEm). Results showed that HP, HI and RE in the fed state increased with ME intake level (p<0.05). Based on the regression of HP on ME intake, the estimated ME requirements for maintenance (MEm) was 113.09 kcal/kg BW0.75 per d when ME intake equals HP. The FHP was decreased day by day with the lowest value on the third day of starvation. Except for lowest ME intake level, the FHP increased with ME intake level on the first day of starvation (p<0.05). The FHP at the two higher ME intake levels were greater than that at the two lower ME intake levels (p<0.05) but no difference was found between the two lower ME intake levels. Linear regression of HP from the fed state to zero ME intake yielded a value of 71.02 kcal/kg BW0·75 per d, which is higher than the extrapolated FHP at zero ME intake (60.78, 65.23 and 62.14 kcal/kg BW0.75 per d for the first, second and third day of fasting, respectively). Fasting time, lighting schedules, calculation methods and duration of adaptation of hens to changes in ME intake level should be properly established when using indirect calorimetry technique to estimate dietary NE content, MEm and NEm for laying hens.

Highlights

Evaluation of energy content of feeds for laying hens is usually based on their metabolizable energy (ME) contents
General observations Throughout the whole experiments periods, no laying hens were found in poor condition or dead
The mean retained nitrogen increased with ME intake from 0.24 g/kg BW0.75 per d at the lowest ME intake to 0.93 g/kg BW0.75 per d at the highest ME intake

Summary

Introduction

Evaluation of energy content of feeds for laying hens is usually based on their metabolizable energy (ME) contents. As ME is not a predictor of how efficiently the bird uses what is available (Macleod, 2000), net energy (NE) system has been proposed. When using a factorial analysis procedure to estimate NE values of diets, NE for maintenance (NEm) must be estimated (Noblet et al, 1994). The maintenance energy requirement is essentially an ATP requirement. The ME requirement for maintenance (MEm) was considered to be diet-dependent due to differences between nutrients, but NEm expressed as ATP needs in a non-producing state ought to be independent of nutritional level and related to animal state only. MEm for animals is usually estimated by establishing regression of heat

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