BACKGROUND
Pea (Pisum sativum L.) is an attractive alternative protein and energy source for poultry because it can be grown widely and contains relatively high concentrations of crude protein and starch. Its nutritional use is limited in part by the presence of resistant starch, which is digested poorly or not at all. Because extrusion can reduce resistant starch but adds cost, the investigators evaluated whether exogenous amylase could improve nutrient utilization more economically. They specifically hypothesized that adding exogenous amylase to pea-based diets for broiler chickens would improve digestibility, energy value, and possibly reduce endogenous losses estimated by excreted sialic acid.
METHODS
This was a controlled animal feeding experiment in 84 1-day-old male Ross 308 broiler chickens with an initial individual weight of 42 ± 2 g. The design included 3 treatments, each with 14 replicates and 2 birds per replicate. From 1 d to 16 d, all birds received a corn-soybean meal reference diet. After 16 d, treatment 1 continued on the reference diet, while treatments 2 and 3 received diets in which 50% of the reference diet was replaced with 50% pea seeds. Treatment 3 additionally received exogenous α-amylase at 0.14 g/kg; 80 KNU/kg as fed, using a commercial product (Rononzyme HiStarch; DSM Nutrition, Heerlen, The Netherlands). Titanium dioxide was included at 3 g/kg as fed as an indigestible marker. Excreta were collected 3 times daily on 21 d and 22 d, and birds were euthanized on 23 d for collection of ileal digesta from the 15 cm segment adjacent to the ileocecal junction. Nutrient digestibility and AMEN were calculated using the difference method and marker-based equations. Statistical analysis was performed in SAS (2012), using a t-test with significance at p ≤ 0.05.
KEY RESULTS
Overall mortality was low (<2%) and was not attributed to dietary treatment. The principal finding was that amylase supplementation significantly improved the apparent ileal digestibility (AID) of several key nutrients in pea seeds. Dry matter AID increased from 0.691 to 0.730 (p < 0.05). Crude protein AID increased from 0.800 to 0.864. Starch AID increased from 0.852 to 0.886 (p < 0.05). The authors also stated that amylase significantly increased starch digestibility by 8.00% (p < 0.05), dry matter digestibility by about 5.64%, and crude protein digestibility by 3.99%.
For energy utilization, no statistically significant difference in AMEN was observed between the non-supplemented and amylase-supplemented pea diets. However, the authors reported a tendency toward improvement, with p = 0.076. Exact AMEN values were not clearly reported in the provided text.
Amylase also improved amino acid utilization. According to the authors, the AID of almost all essential amino acids increased significantly, except for phenylalanine (Phe; p < 0.05 for the significant comparisons). The maximum improvement in AID among essential amino acids was 8% for threonine (Thr) and isoleucine (Ile). A 7.00% increase was noted for lysine (Lys) and valine (Val). Among non-essential amino acids, only proline (Pro) showed a significant increase, described as an almost 12.00 % improvement (p < 0.05). Exact digestibility coefficients for individual amino acids were not clearly reported in the provided text.
The study also measured excreted total and free sialic acid as markers of endogenous losses. No significant differences in the amount of excreted total and free sialic acids were observed with amylase supplementation. Exact values for sialic acid excretion were not clearly reported in the provided text.
The paper provides some compositional context for the pea seeds. The resistant starch content was reported as 136.6 g/kg as fed. The authors also cited a previously reported amylose-to-amylopectin ratio in pea seeds of 31:69, classifying pea starch as type C, which is less readily hydrolyzed than type A starch in corn. They used this to explain why an exogenous starch-degrading enzyme might have a particularly useful effect in pea-based diets.
CLINICAL IMPLICATIONS
Although this was not a human clinical study, the work has practical implications for veterinary nutrition and commercial poultry feeding. The findings suggest that exogenous amylase can enhance the nutritional value of pea seeds by improving ileal digestibility of dry matter, crude protein, starch, and most essential amino acids when pea replaces 50% of a reference broiler diet. This is relevant because pea is a potential alternative to soybean meal, especially in non-GMO feed strategies. The lack of a statistically significant AMEN increase indicates that improved digestibility does not necessarily translate into a clearly measurable energy benefit under these conditions, though the trend at p = 0.076 suggests a possible effect that may require larger studies to confirm. The absence of change in sialic acid excretion also suggests that amylase’s main benefit may be improved nutrient hydrolysis rather than reduced endogenous losses. Overall, the study supports amylase supplementation as a potentially cost-effective strategy to improve the feeding value of pea in broiler nutrition, but its conclusions are limited to a short-term broiler model and should not be extrapolated to human medicine.