The effect of dietary calcium inclusion on broiler gastrointestinal pH: Quantification and method optimization

Abstract

There is little consensus as to the most appropriate methodology for the measurement of gastrointestinal pH in chickens. An experiment was conducted to establish the optimum sampling method for the determination of broiler digesta pH in birds fed differing levels of dietary calcium. Ross 308 broilers (n = 60) were fed 1 of 2 experimental diets, one containing 0.8% monocalcium phosphate and 2% limestone and one containing 0.4% monocalcium phosphate and 1% limestone. Four factors were investigated to determine the most appropriate method of measuring broiler gastrointestinal digesta pH: removal from the tract, prolonged air exposure, altering the temperature of the assay, and controlling the water content of the digesta. The conditions were assessed at bird ages from 7 to 42 d posthatch. Dietary Ca content had no significant effect on in situ pH, but it contributed toward variance in ex situ pH of both gizzard and duodenum digesta. Digesta pH read higher when the digesta was removed from the tract, but the amount of time the digesta was exposed to air did not affect the reading. Digesta pH read higher when measured at room temperature than when measured at 41°C; temperature made the strongest unique contribution to explaining variance in duodenum pH, and the second strongest contribution to explaining variance in gizzard pH, after diet. When water was added to the digesta, before pH determination, the pH of the digesta read higher (P < 0.001) than when measured in situ. The method that resulted in pH readings that were most representative of bird gastrointestinal environment was insertion of a pH probe directly into the gut lumen posteuthanasia, because measurement ex situ likely encourages dissociation of carbonic acid, the major buffer in the gastrointestinal tract, which causes pH to read to be higher than when measured in situ. This study shows that the method of pH measurement needs careful consideration to ensure the validity of the result.

Characterization of the Intestinal Microbiota and Metabolites of Broiler Breeders with Different Egg Laying Rate

“…Similar observations have been made in broiler chickens and laying hens [54,55]. Diet is a well known factor that can influence the microbiota composition and metabolic activity [56,57]. For example, an altered abundance of Bacteriodetes and Firmicutes has been observed in animals fed a high fat diet [58][59][60], however as the same diet was to the fed AR and HR birds this could probably explain the lack of differences in bacterial communities between the two groups.…”

Effects of different rearing systems on growth, small intestinal morphology and selected indices of fermentation status in broilers

“…VFA, produced by intestinal microbiota determines the pH of intestinal digesta (Whittow ). The pH of intestinal digesta is one of the major gastrointestinal factors that manage the potential for optimum gut health (Morgan et al ). A previous study has reported that stocking density was associated with the changes in the pH of intestinal digesta (Tsiouris et al ), and had a significant effect on commensal bacterial microbiota of the intestine of chickens (Guardia et al ).…”

High stocking density as a predisposing factor for necrotic enteritis in broiler chicks

“…Therefore, the manipulation of digesta pH in broiler chickens could act as a tool to manage the potential for optimum gut health and maximum nutrient absorption (Gabriel et al, 2006;Morgan et al, 2014). Moreover, digesta pH has been used as a tool for the prevention of intestinal pathogens such as Salmonella spp, Campylobacter spp.…”