The impact of stocking density on the performance, health and welfare of turkey hens
The impact of graded levels of stocking density (SD) on the performance, health, and welfare, of Nicholas Select turkey hens raised from day 0 to 11 weeks of age were evaluated in this study. Poults (n=3550/block; randomized complete design with block as trial) were randomly placed into one of four final estimated SD treatments of 30, 40, 50, or 60 kg/m2 based on final predicted body weight at 11 weeks of age. Birds were housed in open rooms (67.5m2) with a total of four replications per treatment. Feeder and drinker space were equalized on a per bird basis. Based on CO2 and ammonia measures, ventilation was adjusted to equalize air quality across all treatments. Productivity was evaluated by measuring group body weight and feed consumption on day 0 and in weeks 3, 5, 8, and 11. Body weight gain and feed-to-gain ratio were calculated. At week 8 and 11, flock uniformity was evaluated on 30 birds/replicate. A brief economic analysis utilizing 2019 and 2020 poult and feed costs was performed. At week 8 and 11, footpad lesions, mobility (subjective gait scores) and feather cover and cleanliness were evaluated on 30 birds/replicate and litter samples were collected to determine moisture content (block 1 only). Incidences of aggressive pecking were recorded daily. Heterophil/lymphocyte (H/L) ratios were evaluated at 3, 5, 8, and 11 weeks of age (20 birds/replicate). Behavioural activity was recorded, and scan sampled (field of view observations) at 8 and 11 weeks of age. Data were analyzed using regression analysis in SAS 9.4 (Proc Reg and Proc RSReg; SD as independent variable). An analysis of variance was performed for all data (Proc Mixed; SAS 9.4) and a Tukey’s range test was used to separate means. Differences were considered significant when P0.05, and trends were noted when P0.10. Ammonia and CO2 were consistent across treatments for both blocks. Body weight (week 11) decreased linearly as SD increased. Feed consumption was lowest at high SD (linear for week 8-11; quadratic for week 0-11). Overall body weight gain tended to decrease as SD increased. Feed-to-gain ratio, percent mortality, and uniformity were not affected by SD. Total aggression related mortality and culls linearly increased with decreasing SD. Net room income linearly increased as SD increased. Average footpad scores worsened at week 8 as SD increased. Mobility was poorer in the 60 kg/m2 treatment at week 11. Feather cover and cleanliness scores were poorer in the high SD treatment at week 8 and 11. Incidence of aggressive damage was highest at low SD (30 kg/m2). The H/L ratios increased linearly with increasing SD at 5 weeks of age. At 8 weeks, H/L ratios were highest in the 40 kg/m2 treatment (quadratic) and at 11 weeks, were highest in the 50 and 60 kg/m2 treatments (quadratic). Behaviour was impacted with increasing SD as the percentage of birds resting, feather pecking, and total disturbances increased. The percentage of birds standing, walking, litter pecking, environmental pecking, and performing aggressive behaviours increased with decreasing SD. Litter moisture tended to increase with increasing SD at week 11. Overall, turkey hen performance, health, and welfare were negatively affected at higher SD although economic returns were greater. Conversely, the lowest SD (30 kg/m2) also negatively affected welfare as more aggression occurred.
behaviour, body weight, air quality, feed consumption, footpad lesions, mobility, aggression, stress
Master of Science (M.Sc.)
Animal and Poultry Science