Walailak Procedia 2019; 2019(1): IC4IR.73 http://wjst.wu.ac.th/index.php/wuresearch International Conference on 4 th Industrial Revolution and Its Impacts, 27-30 March 2019, Walailak University, Thailand Effects of dietary fiber on growth performance, fecal ammonia nitrogen, and gastrointestinal tract pH in broilers from 1 to 21 days of age Sabilio DOS SANTOS 1 , Chaowanee LAOSUTTHIPONG 1 , Koh-en YAMAUCHI 2 , Narin THONGWITTAYA 3 and Janjira SITTIYA 1,* 1 Faculty of Animal Sciences and Agricultural Technology, Silpakorn University, Petchaburi 76120, Thailand 2 Laboratory of Animal Science, Faculty of Agricuture, Kagawa University, Kagawa 761-0795, Japan 3 Faculty of Animal Sciences and Technology, Maejo University, Chiang Mai 50290, Thailand ( * Corresponding author’s e-mail: sittiya_j@silpakorn.edu) Abstract The present study was conducted with starter chickens (1 to 21 days of age) to investigate the effects of dietary fiber on growth performance, fecal ammonia nitrogen, and gastrointestinal tract pH. A total of 420 one-day-old Ross 308 chicks were divided into five groups with seven replicates of twelve chicks each. The experimental diets, which contained different sources and levels of fiber, were as follows: none (control); 2.5% rice hulls (2.5% RH); 2.5% soybean hulls (2.5% SH); 5.0% rice hulls (5.0% RH), and 5.0% soybean hulls (5.0% SH). All diets were formulated to be isocaloric and isonitrogenous. Chickens were placed in cage under continuous lighting, and had ad libitum access to diet and water from 1 to 21 days. The body weight gain of broilers in the control, 2.5% RH, 5.0% RH, and 5.0% SH groups were significantly higher than those of the 2.5% SH group (p < 0.05). Fecal ammonia nitrogen of broilers decreased in the 2.5% RH and 5.0% SH groups (p < 0.01). Fiber inclusion reduced gizzard pH (p < 0.05) but did not alter duodenum, jejunum, and ileum (p > 0.05). These findings suggest that the inclusion of different fiber sources in the diet of young broilers improves gizzard pH, resulting in decreased levels of fecal ammonia nitrogen. Keywords: Rice hull, soybean hull, young broilers Introduction At present, increasing levels of livestock production are causing many environmental problems. Animal manure from livestock production can be a cause of ammonia (NH 3 ) emission, which impacts both animal and human health. Nitrogen (N) content in feces containing undigested dietary N, endogenous N, and microbial N (Jha & Berrocoso, 2016) can lead to NH 3 emission to the atmosphere and later converted to nitrate during storage (Ferket et al. 2002). NH 3 emissions contribute to acid rain and nitrogen deposition that damage natural ecosystems. Many researchers have used the diet composition improving method to decrease manure pollutants. Interestingly, dietary fiber has been shown to lower NH 3 emission from pigs (Canh et al. 1997; Shriver et al. 2003) and laying hens (Roberts et al. 2007). Fiber is naturally present in plant-based feed ingredients, and constitutes an important component in poultry diets. Historically, dietary fiber has been considered a dietary diluent, with a negative impact on voluntary feed intake, growth performance, and carcass quality (Janssen & Carré, 1985; Mateos et al. 2002; Rougière & Carré, 2010). Some studies, however, have shown that fibrous material in moderate levels enhances growth performance of broiler chicks (Jiménez- Moreno et al. 2009; González-Alvarado et al. 2010). Other research has reported on the favorable effects of a moderate dosage of insoluble fiber in the diet. Findings have shown that the inclusion of dietary fiber may improve HCl (Jiménez-Moreno et al. 2010), bile acids, enzyme secretion (Hetland et al. 2003), and better gizzard function (Hetland et al. 2005), all of which contribute to improved nutrient digestibility and performance traits of broilers (Jiménez-Moreno et al. 2009). The effects of dietary fiber on gastrointestinal tract (GIT) physiology, microbiota growth, and poultry behaviour differ according to the source of fiber and the nutritive characteristics of the diet (Shakouri et al. 2006; Saki et al. 2011). For example, insoluble, highly lignified fiber might have different effects on the GIT than does soluble, low-lignin fiber. In this respect, insoluble fiber sources, such as rice hulls (RH), increase retention time in the upper part of the GIT, thus stimulating gizzard development and endogenous enzyme production. The result is improved digestibility of starch, lipids, and other dietary components (Mateos et al. 2002; Hetland et al. 2003; Hetland et al. 2005). The physical structure of the feed might also affect the response of birds to the inclusion of fiber in their diet. The digestive system of newly hatched chicks is not completely adapted to the feed digestion and absorption. As such, during this period, the development of the gastrointestinal tract is stimulated by feed consumption (Longo et al. 2007). In similarly report, feed intake and intestinal development were controlled in the young chicks to meet the nutrient requirements (Uni et al. 1999). The nutritional and physiological effects must be considered, however, these effects caused by the amount of cell wall and their chemical composition, as well as structure. Therefore the aim of this experiment was to investigate the effects of dietary fiber on growth performance, fecal ammonia nitrogen, and gastrointestinal tract pH in broilers from 1 to 21 days of age.