Cereal grain fiber composition modifies phosphorus digestibility in grower pigs

Area of Science:

• Animal Nutrition
• Digestive Physiology
• Agricultural Science

Background:

• Increased fermentable carbohydrates like beta-glucan and amylose can enhance endogenous phosphorus (P) losses, reducing P apparent total tract digestibility (ATTD).
• Understanding the impact of different cereal grains, particularly barley cultivars, on P and inositol phosphate (InsP) digestibility is crucial for optimizing animal diets.

Purpose of the Study:

• To assess the effects of barley cultivars with varying fermentable starch and fiber content on the apparent ileal digestibility (AID), ATTD, and standardized total tract digestibility (STTD) of phosphorus (P).
• To evaluate the digestibility of myo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate; InsP6) and calcium (Ca) in pigs fed different cereal grains.
• To determine the presence of lower inositol phosphates (InsP) and their contribution to P release compared to wheat.

Main Methods:

• A 6 (period) × 5 (diet) Youden square design was employed with seven ileal-cannulated barrows.
• Diets were formulated with 80% of one of five cereal grains: high-fermentable, high-β-glucan hull-less barley (HFB); high-fermentable, high-amylose hull-less barley (HFA); moderate-fermentable hull-less barley (MFB); low-fermentable hulled barley (LFB); and low-fermentable Canadian Western Red Spring wheat (LFW).
• Apparent ileal and total tract digestibility of P, InsP6, and Ca were measured, along with the concentration of various inositol phosphates.

Main Results:

• Diets with moderate-fermentable hull-less barley (MFB), low-fermentable hulled barley (LFB), and low-fermentable wheat (LFW) exhibited greater P AID than HFB and HFA.
• MFB showed greater P ATTD and STTD compared to HFB.
• Apparent total tract digestibility of InsP6-P was higher for HFB than LFB, and the sum of InsP6-2-P was greater for HFB and HFA than LFB, indicating greater P release from InsP hydrolysis in high-fermentable grains.

Conclusions:

• Cereal grains high in fermentable fiber, such as amylose and β-glucans in specific hull-less barley cultivars, resulted in lower P AID, ATTD, and STTD.
• Carbohydrate fermentation in the gut leads to increased total tract P release from inositol phosphates (InsP).
• Dietary β-glucan content was not significantly correlated with P or InsP digestibility, suggesting other factors influence nutrient availability.