Association between digesta pH, body weight and nutrient utilization in chickens of different body weights and at different ages

Relationships between digesta pH, body weight and nutrient utilization of broilers at different ages were investigated in the current study. Ninety 1-d old chicks were raised together for 10 d, and then were divided into 3 groups of 30 birds each for the starter, grower, and finisher phases batches. Each batch was divided to two groups comprising the 10 lightest (L) and the 10 heaviest (H) birds with the 10 median birds excluded from study. At the end of each phase, the digesta pH of the intestinal sections was measured in the birds. The ileal digesta and total excreta voided were collected for nutrient and energy utilization determination. In starter and grower phases, the H birds consumed more feed (P＜0.05) and grew faster (P＜0.05) than the L birds. The H birds had lower (P＜0.05) digesta pH compared with the L birds irrespective of the phase. The digesta pH was lower (P＜0.05) for birds during the grower than during the starter phase (except in the crop) and greater (P＜0.05) during finisher compared with grower phase (except in the crop and jejunum). The birds in H group had lower (P＜0.05) proventricular pH compared with the L group independent of the age of birds whereas the cecal pH was lower (P＜0.05) for birds in H group during the grower phase. The crop, caecal, and jejunal pH at different growth phases had positive correlation with the ileal energy digestibility and total tract nutrient and energy retention. It was concluded that individual variability in body weight and nutrient utilization in grower and finisher phases were partly explained by variability in jejunal.