The effects of stocking density on heavy turkey tom productivity, health, and wellbeing to 16 weeks of age

Abstract

The impacts of increasing stocking density (SD) were observed on Nicholas Select turkey toms (n=2,868) to 16 wk of age. In two trials, birds were allocated to 8 independently controlled rooms (6.7x10.0 m = 67.5 m2) based on final predicted body weight, resulting in a total of 4 room replicates per treatment. Air quality was monitored via carbon dioxide and ammonia and was equalized across treatments. The number of birds placed differed by density to reach a final predicted density (based on Aviagen, 2015a Performance Objectives) of 30, 40, 50, and 60 kg/m2. Productivity was evaluated using body weight and feed consumption at 0, 4, 8, 12, and 16 wk of age, and feed efficiency was calculated at 4 wk intervals. A brief economic analysis was conducted based on productivity. At 12 and 16 wk of age, a sample of 20 birds per replicate were weighed for determination of flock uniformity, feather condition and cleanliness, footpad lesions, and mobility. The heterophil/lymphocyte ratio (H/L) was evaluated at 4, 12, and 16 wk (15 birds per replicate) and core body temperature was evaluated at 16 wk (3 birds per replicate). Behavioural expression was analyzed at 12, 14, and 16 wk using a scan sampling technique. Data were analyzed using regression analyses (Proc Reg for linear and Proc RSReg for quadratic relationships; SAS®9.4). Differences were significant when P≤0.05, and trends were noted when P≤0.10. Overall body weight and body weight gain decreased linearly as SD increased. Feed consumption decreased linearly as SD increased within the last 4 wk (12-16). Mortality corrected feed-to-gain ratio demonstrated an increasing linear relationship with SD beginning at 4 wk and continuing throughout the trial. Body weight uniformity and total percentage mortality and culls showed no impact in relation to increasing SD. Footpad lesion severity and frequency and bird mobility were negatively impacted in relation to increasing SD. Feather condition and cleanliness decreased linearly with increasing SD over the course of the trial. The H/L ratio demonstrated an increasing linear relationship with increasing SD at 4 wk of age. Core body temperature increased with increasing SD. Behaviour was altered in relation to increasing density with increases in comfort behaviours, decreases in nutritive behaviours, and quadratic effects on mobility behaviours. The economic analysis, based on production parameters alone, supported increased monetary return with increasing SD. High levels of SD negatively impact bird performance, health and wellbeing, although the economic return continues to improve with increasing density.