Description and Validation of Flow-Through Chambers of Respirometry for Measuring Gas Exchange in Animal Trials.

Indirect calorimetry (IC) is a widely used method to study animal energy metabolism by measuring gas exchange. The accuracy of IC depends on detecting variations in signals reflecting the metabolic response, which can be challenging due to measurement noise and external factors. This study proposes a methodology to validate IC systems, including an easy-to-use spreadsheet for data computing, to verify accuracy and detect whole-system leaks.

The Response to Dietary Leucine in Laying Lens.

This study aimed to estimate the standardized ileal digestible leucine intake (SID-Leu, mg) in laying hens for maintenance, and to describe the response in laying hens to SID-Leu, thereby providing the information required to determine the optimum economic intake of SID-Leu for laying hens. Two nitrogen balance series, one balanced and the other unbalanced with respect to leucine (Leu), were used to estimate the SID-Leu requirement for maintenance using 36 roosters per series. The roosters were randomly distributed among the six levels of Leu with each level being replicated six times.

Dynamic of heat production partitioning in rooster by indirect calorimetry.

Objective: The objective of this study was to describe a methodological procedure to quantify the heat production (HP) partitioning in basal metabolism or fasting heat production (FHP), heat production due to physical activity (HPA), and the thermic effect of feeding (TEF) in roosters.

Methods: Eighteen 54-wk-old Hy Line Brown roosters (2.916±0.

Effect of feed restriction on the maintenance energy requirement of broiler breeders.

Objective: This study aimed to evaluate the effect of the ad libitum and restricted feeding regimen on fasting heat production (FHP) and body composition.

Methods: Twelve Hubbard broilers breeders were selected with the same body weight and submitted in two feeding regimes: Restricted (T1) with feed intake of 150 g/bird/d and ad libitum (T2). The birds were randomly distributed on the treatments in two runs with three replications per treatment (per run).

Modelling Broiler Requirements for Lysine and Arginine.

Six assays were conducted to investigate male and female broiler responses to standardized ileal digestible (SID) lysine (Lys) and arginine (Arg). Response data were modeled to estimate the efficiency of utilization () of both amino acids and adjust factorial models to predict bird intake for SID Lys and SID Arg. In each assay, 1280 Cobb 500 broilers (640 male and 640 female) were randomly assigned to one of sixteen dietary treatments with four replicates of 20 birds.

Optimal in-feed amino acid ratio for laying hens based on deletion method.

A total of 56 Hy-line W-36 hens from 28 to 30 weeks were used on nitrogen balance (NB) trial to estimate daily N maintenance requirements (NMR) and the genetic potential for daily N retention (NR T). The treatments consisted of six graded levels of nitrogen in the diets (N1 = 8; N2 = 16; N3 = 24; N4 = 32; N5 = 40; and N6 = 48 g N/kg of feed), formulated using the dilution technique. The regression analyses between nitrogen intake and excretion were performed to fit the exponential function and to determine the NMR = 292 mg/BW , which was applied for further calculation of NR T = 1,883 mg/BW .