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Huntsville, AL, United States

Deep A.,University of Saskatchewan | Raginski C.,University of Saskatchewan | Schwean-Lardner K.,University of Saskatchewan | Fancher B.I.,Cummings Research Park | Classen H.L.,University of Saskatchewan
British Poultry Science

1. Research focused on lower light intensity levels is required to set minimum standards appropriate for production and welfare of intensively housed broilers. The objective of this research was to study light intensity (0.1 to 10 lx) effects on Ross × Ross 308 and 708 genotypes.2. Three experiments (35 d each) using 18 720 broilers were conducted with the initial experiment using two replicates of 0.1, 1, 5 and 10 lx. The second and third experiments examined 0.5, 1, 5 and 10 lx with treatments replicated twice in each experiment in a randomised complete block design with experiment acting as a block. In each experiment, mixed sex broilers from each genotype were housed in 6 equally sized pens per room.3. In Experiment 1, the introduction of 0.1 lx at d 7 caused high levels of mortality and poor growth rate from d 7 to 14 and was discontinued.4. In Experiments 2 and 3, increasing light intensity increased body weight gain (0-35 d) and feed intake (0-35 d) in a quadratic and linear fashion, respectively. Similarly, mortality corrected gain to feed ratio (FCR, 0-35 d) demonstrated a quadratic response with a maximum at 5 lx. Carcass, breast meat and skin, abdominal fat and drum skin, as a percentage of live weight, increased while drum bone and wing yield decreased in a linear fashion with increasing light intensity. Total carcass composition was unaffected by light intensity.5. Genotype effects were numerous. No interactions were found between genotype and light intensity.6. Ocular dimensions and the incidence of foot pad lesions decreased in a quadratic and linear fashion, respectively, with increasing light intensity. In contrast, welfare-associated gait score and mortality levels were not affected by light intensity.7. It was concluded that performance, breast meat yield and bird welfare improved with increasing light intensity. The data support 5 lx as a minimum light intensity in broiler production. © 2013 British Poultry Science Ltd. Source

Schwean-Lardner K.,University of Saskatchewan | Fancher B.I.,University of Saskatchewan | Fancher B.I.,Cummings Research Park | Classen H.L.,University of Saskatchewan
British Poultry Science

1. The impact of daylength on productivity in male and female broilers of two genotypes was studied in two replicated experiments. In each experiment, four lighting programs (14L:10D (14L), 17L:7D (17L), 20L:4D (20L) and 23L:1D (23L)) were used to study the relationships between productivity and daylength in two genotypes and both genders.2. General Linear Model analysis was used to test for differences in daylength, genotype, gender and their interactions, and regression analysis to define relationships between productivity and daylength in experiment one and daylength differences in experiment two.3. In experiment one, body weights at d 32 (P = 0·002) and d 39 (P = 0·011) were related in a quadratic fashion to daylength, with the heaviest birds raised under 20L. The growth curve at d 49 was similar in shape, and body weights under both 17L and 20L were significantly higher than under 14L and 23L (P < 0·001). In experiment two, data were similar, although the quadratic relationship was not significant.4. Feed consumption was highest to d 39 or d 49 under 20L, and birds under 23L ate as much (d 39) or less feed (d 49) than under 17L.5. Gain-to-feed efficiency (FCR) responded in a quadratic fashion, with maximum efficiency observed under the shortest daylength.6. Mortality increased linearly with daylength for all time periods in both experiments. © 2012 Copyright Taylor and Francis Group, LLC. Source

Schwean-Lardner K.,University of Saskatchewan | Fancher B.I.,Cummings Research Park | Laarveld B.,University of Saskatchewan | Classen H.L.,University of Saskatchewan
British Poultry Science

1. Ross × Ross 308 male broilers were used to study the impact of 14, 17, 20 and 23 h of light (L) on flock behavioural patterns and 24 h melatonin rhythm synchrony during the photophase.2. Behaviour in two pens (n = 53) per lighting treatment was digitally recorded for 24 h in trial 1 (27-28 d of age (d 27)) and two (42-43 d (d 42)), and quantified using a scan sampling technique at 10 min intervals. Regression procedures were used to test flock trend analysis between behavioural (resting, standing, walking and feeding) variables and time during the photophase.3. The presence of a flock melatonin rhythm was determined by radioimmunoassay of blood samples collected at 6 times for birds raised on 23L and 8 times for 14, 17 and 20L birds (n = 6 per time) over a 24 h period (d 21) in experiment 1.4. Quadratic and linear relationships between time and behaviour during the photophase were frequent in 14L and 17L birds, sporadic in 20L birds and non-existent in 23L birds. Relationships were noted in inactive resting (d 27: 14L and 17L; d 42: 14L and 20L), walking (d 27: 14L and 17L), standing (d 27 and d 42: 14L, 17L and 20L) and feeding (d 27: 14L and 17L). A quadratic time × melatonin relationship existed in 14L, 17L and 20L flocks only.5. Behaviour during the photophase and 24 h melatonin production indicates that flocks exposed to 23L do not develop synchronised rhythms, increasing the risk of suffering from sleep fragmentation. © 2014 British Poultry Science Ltd. Source

Schwean-Lardner K.,University of Saskatchewan | Fancher B.I.,Cummings Research Park | Gomis S.,University of Saskatchewan | van Kessel A.,University of Saskatchewan | And 2 more authors.
Poultry Science

An experiment was conducted to study the effect of day length, sex, and genotype (Ross × Ross 308 and 708) on mortality causes, bird mobility, footpad health, and ocular size, with 4 trials within the experiment. Four graded day lengths were chosen to allow the study of relationship between day length and health parameters, including 14L: 10D, 17L: 7D, 20L: 4D, and 23L: 1D. The primary statistical tools used to assess the day length relationships were regression analysis (Proc Reg and RSReg of SAS). Data were also analyzed as a 4 (lighting program) × 2 (sex) × 2 (genotype) factorial arrangement. Total mortality, as well as mortality due to metabolic and skeletal disease, decreased linearly with increasing inclusion of darkness (7-to 32-, 7-to 38-, and 7-to 48-d periods). Infectious disorders were quadratically related to day length (7-to 48-d period only), with birds under 20L having the highest level. Day length was linearly or quadratically related to average gait score in a positive fashion, and the incidence of birds falling in painful gait score cat-egories increased linearly with increasing day length. Average footpad lesion scores increased with increasing day length (28 and 35 d). The 23L photoperiod resulted in heavier eye weights than other lighting programs. Males had a higher mortality and morbidity rate and a higher average gait score than females. Average footpad score was lower for males than females (28 and 35 d). Overall mortality was higher for 308 than 708 broilers; hence, levels of specific mortality causes were higher. Average gait scores were lower for 308 than 708 birds in 2 of the 3 time periods measured and footpad le-sions were higher. To conclude, many aspects of broiler health improve with decreasing day length. © 2013 Poultry Science Association Inc. Source

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