Nutritional and Environmental Factors Affecting Feed Intake Level and Pattern in Growing and Finishing Pigs

228 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1997.A series of experiments were conducted to determine the effects of nutritional and environmental factors on growth performance, feed intake level and feed intake pattern using Feed Intake Recording Equipment in growing and finishing pigs. Barrows had a greater number of meals per day than boars and gilts. Daily feed intake increased with dietary lysine content due to increased meal sizes. There was one peak feeding behavior between 0900 and 1100 and lower feeding activity between 2000 and 0400. Repeatabilities of feeding pattern traits were higher when measured over shorter time periods. There was a change in feeding behavior with increasing dietary lysine levels on feeding pattern for mixed-sex groups. Pigs with larger feed intake per visit and faster feed consumption rate had better growth performance and greater leanness. Further experiments were conducted to determine the effects of temperature, space allowance and mixing on feed intake level and pattern, and hematological and behavioral changes. Growth performance and feed intake were depressed linearly as number of stressors increased. This performance depression was related to increased plasma cortisol level and reduced feeding activity affected by the stressors. Pigs on the restricted floor space made fewer and longer feeder visits and had higher feed intake per visit than uncrowded pigs. Mixing stress reduced the number of feeder visits per day and increased feeder occupation time and feed intake per visit in the first week after mixing. Feeding behavior was changed by crowding and mixing stress affects animals performance and behavior temporarily. Final experiments were carried out to determine the effects of different types of feeder and group size on growth performance, feed intake level and pattern, hematological and behavioral changes. Pigs on the FIRE system feeder consumed less feed because the system gives more protection, but grew at a similar rate to pigs on conventional feeders. Feed intakes and growth rates declined linearly with increasing group size in growing pigs. Pigs on the FIRE feeders changed feed intake patterns by the group size. No effect of feeder type and group size on plasma cortisol and digestibility of dry matter and crude protein was found.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD