The Effects of Simulated Transport Conditions (Temperature and Relative Humidity Combinations at Various Durations) on Turkey Tom Behaviour, Physiology, and Meat Quality Traits
Date
2025-06-25
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0009-0003-6094-859X
Type
Thesis
Degree Level
Masters
Abstract
Pre-slaughter stressors, especially those experienced during transportation, can affect bird welfare and meat quality. The aim of this study was to evaluate the effects of temperature and relative humidity combinations (T/RH) and duration (D) during simulated transportation on 16-wk-old turkey tom behaviour, physiology, and meat quality. Treatments (trt) were arranged in a 2 by 5 factorial arrangement (D; 4 or 8 h; T [°C ]/RH [%]; 30/80, 30/30, 15/80, 15/30, or -20/uncontrolled), with four replicate crates (four birds/crate, two crates per flock) per T/RH and D combination. After a 4-h feed restriction, initial blood samples were taken, birds were gavaged with a T data logger (crop/gizzard temperature; CGT), weighed (calculate body weight loss (live shrink; %), and then crated. Once crated, the birds were placed in an environmental chamber on purpose-built vibration tables (24.4 Hz) for the D of simulated transport. During exposure, videos were recorded to analyze bird behaviour using instantaneous scan sampling at 5-min intervals to estimate the percentage of time spent performing behaviours. Post-exposure, blood samples were collected for final measurements, and delta (Δ) values were calculated for corticosterone (CORT) concentration, heterophils-to-lymphocytes ratio (H/L), and blood parameters (pH, partial pressure of carbon dioxide, partial pressure of oxygen, base excess in extracellular fluid, bicarbonate, total carbon dioxide, oxygen saturation, blood glucose (Glu), sodium, potassium, ionized calcium, hematocrit, and hemoglobin). Birds were weighed to determine final body weight and calculate live shrink before being processed in a small-scale slaughter line. Immediately after evisceration, initial breast and thigh pH were recorded. Two breast samples and one thigh sample were collected and weighed 6 h post-slaughter. Thirty h post-slaughter, final pH, weight (drip loss (%)) and colour readings (L*, a*, b*) were collected on one breast and the thigh sample. To determine thaw and cook loss the second breast sample was frozen for 9 wk post-slaughter. A randomized complete block design (flock as block; SAS 9.4; P≤0.05) was used to analyze data. Toms spent the highest percentage of time panting when exposed to trt with high T/RH (30/30 and 30/80; P<0.01) compared to birds in the other trt. Toms in -20, 15/30 and 15/80 spent a higher percentage of time head resting and motionless (P<0.01) compared to those in the extreme heat. Toms exposed to 30/30, 30/80 and -20 had a greater increase in CORT blood concentrations (P<0.01) than those birds in 15/30; however, ∆ H/L was unaffected. Toms exposed to -20 experienced a greater decrease in blood Glu (P<0.01) compared to those birds in 15/30 and 15/80. Blood pH in birds exposed to 30/80 and 30/30 increased, while those in other trt declined (P<0.01). The combined mortality and cull rates were higher when toms were exposed to 30/80 (P≤0.01), compared to any other trt; however, although there were still mortality and cull rates in the -20 and 30/30 trt, the differences were not significant. Toms had a greater live shrink (%) when exposed to 30/30 and 30/80 than all other trt (P<0.01). Birds exposed to an 8-h D had increased live shrink compared to those exposed to a 4-h D. Breast muscle drip loss was higher when exposed to 30/80 than in all other trt (P<0.01). Meat colour was not affected by D. In conclusion, exposure to -20, 30/80, and 30/30 trt, especially for longer durations, significantly affected turkey tom welfare, increased stress responses, and negatively affected meat quality. These effects were reflected in behavioural changes, blood parameter shifts, difficulty regulating CGT, higher combined mortality and cull rates, and greater live shrink. This study demonstrates the importance of understanding the effects of the exposed temperature and relative humidity during transport on bird welfare, physiological parameters and meat quality.
Description
Keywords
Thermal Stress
Citation
Degree
Master of Science (M.Sc.)
Department
Animal and Poultry Science
Program
Animal Science