1:00 pm - 2:00 pm
A graduate exam seminar is a presentation of the student’s final research project for their degree.
This is an ALES MSc Final Exam Seminar by Nicole Zukiwsky. This seminar is open to the general public to attend.
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Meeting ID: 998 2797 8990
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Thesis Topic: Supply chain evaluation of broiler breeder reproductive management on hunger, reproduction and offspring performance using a precision feeding system
MSc with Dr. Martin Zuidhof.
Body weight (BW) of female broiler breeders is strictly controlled through feed restriction to optimize reproductive performance. A precision feeding (PF) system feeds birds individually based on live BW, which allows for precise feed allocations and BW management. To achieve good flock health and BW targets from a young age, chicks undergo training for the first 3 wk of life to learn how to successfully eat from the PF system. An automated marking system (AMS) was installed in a PF station as a visual method to identify chicks that successfully eat from the station versus those that need additional training. The first experiment in this thesis evaluated if the dye markings from the AMS promoted aggression in broiler breeder chicks. It was hypothesized that the dye markings would not promote aggressive behaviours in broiler breeder chicks. Dye markings from the AMS did not increase aggression from 0 to 21 d of age. The frequency of aggressive pecking increased on d 26, however this is beyond the age at which the AMS is recommended to be used as an identification method. The second experiment of this thesis implemented various BW trajectories to individual broiler breeder females through the PF system. Trajectories were created using a Gompertz growth model that estimated pre-pubertal, pubertal and post-pubertal phases of growth. Each trajectory varied in 2.5% increases in pre-pubertal and pubertal BW gain from 2.5 to 22.5% above the recommended Ross 708 BW target. An additional group of unrestricted females were given access to a meal upon every station visit, meaning they were not limited to a maximum BW. The objective of the second experiment was to investigate various levels of increased BW, and concomitant levels of relaxed feed restriction, on feeding and feed seeking and reproductive performance. It was hypothesized that increased BW (lesser degree of feed restriction) would decrease station visit frequency and meal size, and increase meal frequency and feed intake. In addition, it was hypothesized that increased BW (lesser degree of feed restriction) would reduce egg production and age at first egg, and increase egg weight. It was observed that station visit frequency decreased as BW increased during lay, however, not during the rearing period. Thus, increased BW up to 22.5% above the recommended BW target did not reduce motivation to seek feed and hunger during rearing. Two unrestricted hens came into lay prior to photostimulation (22 wk of age), and egg production was similar across BW trajectories. A third experiment was conducted in extension of experiment two to evaluate the intergenerational effect of increased maternal BW (relaxed feed restriction) on broiler growth performance. Two replicated broiler studies were conducted that varied in maternal age (35 and 42 wk). The main objective of the third experiment was to evaluate increased maternal BW on offspring BW, feed efficiency and carcass traits. It was hypothesized that increased maternal BW would increase offspring BW, breast muscle yield and fatness, and reduce feed efficiency. A second objective was to investigate offspring BW, feed efficiency and carcass traits in response to maternal age and broiler sex. It was hypothesized that offspring BW, fatness, breast muscle, liver, and gut weights would increase, and feed efficiency would decrease with maternal age. In addition, males would be have a greater BW and breast muscle yield, less fat, and would be more efficient than females. There were no significant effects of maternal BW on offspring BW. Broilers from high BW hens were less efficient than those from low BW hens. Proportional gut weight decreased as maternal BW increased, which may have been associated with the reduction in feed efficiency. The effects of maternal age and broiler sex was consistent with the hypotheses. It was concluded that there is potential to increase female broiler breeder BW targets to reduce the level of feed restriction without negatively affecting reproductive performance and offspring growth performance, which would in turn improve broiler breeder welfare.