The effect of starch gelatinisation degree on intestinal morphology, intestinal pH and bacteriology in pigeons

Abstract

The effect of starch gelatinisation degree in extruded feed on intestinal morphology, intestinal pH and faecal bacteriology was investigated in pigeons. Extruded complete pigeon diets would offer the principle advantage of providing equilibrated nutrients and energy, but factors such as starch gelatinisation require investigation before these diets are offered as main dietary items to pigeons. Birds were fed two diets with equal ingredient composition and nutrient content, but with a different degree of starch gelatinisation resulting from altered extrusion processing (high gelatinisation degree (HG) with 73.6% gelatinisation vs. low gelatinisation degree (LG) with 53.1% gelatinisation). Feed intake and weight gain changes were measured weekly. Blood samples were collected at day 28 and analysed for non-esterified fatty acids, lactate dehydrogenase and glucose. The pH values for fresh excreta were measured; thereafter fresh excreta were collected and cultured for measurement of colony-forming units for bacterial classes. At the end, morphological measurements were examined and the pH values throughout the gastrointestinal tract were recorded. Liver, pancreas and abdominal fat were weighed. There was a tendency (p= 0.07) towards higher numbers of Escherichia coli in the excreta of the LG group compared with those in the HG group. No dietary treatment effects were noted on the number of Lactobacillus sp. in the excreta. In proximal parts of the intestine, LG revealed a significantly lower pH than HG. Villus height and crypt depth were not affected by dietary treatment, but the duodenum muscularis thickness, liver weight and pancreas weight were significantly lower in the LG than that in HG group. This trial demonstrated that the lower level of starch gelatinisation degree of extruded feed leads to acidification of the proximal gut and altered gut morphology in pigeons. Hence, extruded pigeon diets should preferably contain low-gelatinised starch instead of high-gelatinised starch. In addition, future research must focus on the effects of starch gelatinisation on the correlation between the intestinal pH, microflora content and intestinal morphology.

Dietary habits of urban pigeons (Columba livia) and implications of excreta pH – a review

“…Diet may influence animal urine pH (Burton 1980) and also the nitrate content in pigeon excreta (Sales & Janssens 2003a, 2003b. Experimental studies found that pigeon diets with a high gelatinisation of the constituent starches (i.e., cooking) resulted in excreta with a higher pH than an identical diet modified to have a lower gelatinisation (Abd El- Khalek et al 2011). While this study is in- dicative only, as the differences were not statistically significant, it nonetheless suggests that processed foods (cooked human discards) may induce a higher pH than unprocessed, natural diets, such as grass seeds.…”

Micromineral Source Affects Intestinal Morphology but not Feather Formation in Pigeons

“…Recently, crude ash digestibility-as a measure of mineral absorption-showed a considerable increase due to decreasing the degree of starch gelatinisation of a complete extruded diet for pigeons [18]. A consecutive trial indicated that intestinal pH and changes in intestinal morphology might attribute to this phenomenon [19]. Therefore, the impact of trace element sources might depend on the composition and processing of the basal diet, which urges-as a next step-for an evaluation of trace element sources in different diets.…”

The diet of adult psittacids: veterinarian and ethological approaches

“…This process of extrusion creates starch gelatinization but also Maillard products and fat hydrogenation among other things. A recent study showed that lower degree of starch gelatinization in extruded diets enhance digestibility in pigeons (Abd El‐Khalek et al., ). Maillard products reduce the availability of amino acids, and fat hydrogenation leads to high level of fatty acids, which could increase the risk of atherosclerosis.…”