Effects of Dietary Pectin and Threonine Concentrations on the Growth Performance, Digestibility and Intestinal Morphology of Broiler Chickens
The experiment was conducted to determine the effect of dietary threonine (Thr) concentration and dietary pectin and the interaction effects of dietary pectin and dietary Thr concentrations on growth performance, nutrient digestibility and intestinal morphology of broiler chickens from d 7 to 21 posthatch. Ten diets with five levels of dietary Thr concentration of 5.7, 7.6, 9.4, 11.3, 13.2 g/kg, representing 60, 80, 100, 120, 140%, respectively, of the Thr requirement suggested by Ross Nutrition Supplement (2009), and two levels of dietary pectin (0 and 7%) were fed to broiler chickens from d 7 to d 21 posthatch in a 5 x 2 factorial arrangement following a RCBD. Silica sand was added to control diet as a replacement of pectin. Chromic oxide was used as an index marker for digestibility coefficient. Individual body weights and feed intakes were recorded at d7, d14 and d21. Excreta samples were collected over a 48h period on d12/13 and d19/20 posthatch, jejunum sections from one heaviest and one lightest bird were collected on d14 and d21, ileal digesta were collected from the remaining birds on d21. Growth performance was determined by BWG, FI and G:F ratio. Nitrogen retention (NR), apparent metabolizable energy corrected for nitrogen (AME n), and ileal digestible energy (IDE) data were analyzed on a DM basis from excreta and ileal digesta samples. Villus heights (VH), crypt depths (CD) and goblet cell counts (GCC) were measured from jejunum samples after AB/PAS stain. Pectin-fed groups had lower BWG, AMEn, IDE, NR, VH, GCC compared with control groups when Thr concentrations were 5.7, 7.6, 9.4 g/kg. When Thr, concentrations were 11.3 and 13.2 g/kg, pectin-fed groups had lower BWG, AMEn and higher GCC compared with control groups. Meanwhile, BWG, FI and G:F ratio increased when Thr concentrations increased from 5.7 to 9.4 g/kg. Overall, these results supported our hypothesis that dietary pectin had a negative impact on the growth performance, intestine morphology development and nutrient digestibility of 7 to 21 day-old broiler chickens when dietary Thr was deficient. However, excess Thr could compensate for the negative effects of dietary pectin on growth performance and intestine morphology development.
Adeola, Purdue University.
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