Effects of a Whole-grain Paddy Rice Diet on the pH Distribution in the Gizzard and Retention Time of Digesta in the Crop of Broiler Chicks

Abstract

We previously reported that a diet containing 65% paddy rice suppressed the colonization of Campylobacter jejuni in the cecum of broiler chicks, suggesting that this type of diet has positive effects on upper gastrointestinal tract function in broilers. To reveal the possible mechanisms involved in this antibacterial effect of the whole-grain paddy rice diet, we performed experiments comparing the digesta passage rate in the crop and gizzard, the development of gizzard, and the pH distribution in the gizzard between groups of chicks fed two different diets, such as ground corn and whole-grain paddy rice. During these experiments, we made the following observations: the chicks in the group fed the whole-grain paddy rice diet had more developed gizzards and significantly larger crop content than the chicks in the group fed the ground corn diet. The chicks fed the whole-grain paddy rice diet retained the digesta in the crop for much longer and had less variation in the pH values in the gizzard than those fed ground corn. On the basis of these observations, we concluded that the hardness of the rice hull in whole-grain paddy rice leads to a larger amount and longer retention of content in the crop, as well as the uniformity of the internal pH of the gizzard, by promoting gizzard activity. We speculate that the hardness of the rice hulls promoted the grinding activity of the gizzard, resulting in the long retention time of the digesta in the crop and uniformity of the internal pH of the gizzard, which may sterilize or suppress Campylobacter growth in the gastrointestinal tract of broiler chicks.

Effect of adding soluble viscous fibers to diets containing coarse and finely ground insoluble fibers on digesta transit behavior and nutrient digestibility in broiler chickens

“…Some of these materials, like oat hulls, can be considered rather hard or resistant to grinding. The harder the iDF, the longer the retention time of the material in the gizzard, as observed by others ( Ferrando et al, 1987 ; Nishii et al, 2016 ). Another possible reason for the lack of PS effects on digesta transit could be related to the insoluble marker used to represent the particulate digesta.…”

Fiber in Broiler Feed: Its Effect on Performance, Gastro-intestinal Tract, and Microbial Profile

“…Penggunaan serat akan mengakibatkan adanya akumulasi pakan dalam gizzard, menurunkan pH gizzard, dan meningkatkan mekanisme refluks antara proventriculus-gizzard dan gizzard-duodenum akan lebih optimal sehingga tingkat kecernaan nutrien pakan menjadi lebih baik (Hetland et al 2004). Penggunaan biji-bijian utuh, seperti gandum utuh (Husveth et al 2015;Singh et al 2014) dan padi (Nishii et al 2016), dan serat dalam pakan ayam broiler dapat menjadi strategi alternatif untuk meningkatkan kecernaan nitrogen dalam pakan yang dapat meningkatkan pertumbuhan ayam broiler (Svihus 2011;. Hetland et al (2003) melaporkan bahwa penambahan sumber serat seperti kulit oat dapat meningkatkan produksi garam empedu dan aktivitas enzim amylase.…”

Survival Time of <i>Campylobacter jejuni</i> in Broiler Crops

“…This natural defense barrier is enhanced by the addition of insoluble dietary fiber to the feed[ 14 ]. In our previous report[ 16 ], the diluted nutrients and hardness of insoluble fiber equivalent to 20% of paddy rice accelerated the grinding activity of the gizzard, which homogenized the pH value in the gizzard and eliminated areas of higher pH where Campylobacter survives. This pH homogenization in the gizzard could prevent Campylobacter colonization of the cecum[ 17 ].…”

“…However, Campylobacter inhibition has not been confirmed in vivo because animal experiments cannot maintain a sufficient residence time to kill Campylobacter in chicken crops. In our previous report[ 16 ], paddy rice fed to broiler chicks increased the residence time in the crop, resulting in an average retention time of 115 min, which allowed observation of the bactericidal activity of the inoculum in the crop. In this study, the survival of Campylobacter remaining in broilers was evaluated by taking advantage of the increased residence time in broiler crops fed paddy rice.…”