Effects of Commercial Processing Conditions of Extruded Soybean on Growth Performance and Amino Acids Digestibility of Broiler Chickens

Published: August 22, 2024

By: A.M. VILLEGAS 1,2; N. YACOUBI 3; A. MENCONI 2 and T.J. APPLEGATE 1 / 1 Department of Poultry Science, University of Georgia, Athens, GA 30602, USA; 2 Evonik Corporation / Nutrition & Care, Kennesaw, GA, 30144, USA; 3 Evonik Operation GmbH / Nutrition & Care 63457 Hanau, Germany.

Summary

Expeller Soybean (SB) is commonly used as the main protein source in broiler diets due to its high amino acid digestibility. Optimal SB processing is required to ensure that antinutritional components that negatively interfere with digestion, absorption, and metabolism of nutrients leading to lower growth performance, are deactivated. In this study, we investigated the effect of 3 commercial expeller SB batches processed at different temperatures, on growth performance, intestinal integrity and amino acid digestibility. A total of 1,860 male Cobb 500 broiler chicks were randomly allocated to the 3 different treatments with 10 replicate floor pens (62 birds/pen) from 0 to 35 d of age. The 3 expeller SB batches were processed with different extruder temperatures of 182, 199, and 154 °C for normal-control (NC), overcooked (OC), and undercooked (UC) SB, respectively. Performance parameters, body weight gain (BWG), feed intake (FI), and feed-to-gain ratio (FCR) were recorded on d 0, 14, 28, and 35. Intestinal integrity was assessed in one bird per pen by determining serum fluorescein isothiocyanate-dextran (FITC-d; 4 kD) concentrations for gut permeability at d 16. The relative weights of the right pectoralis major (RPM) were determined at 35d of age. Intestinal permeability increased in birds fed the OC SBM (P <0.05). On d 14, 28, and 35, birds given the OC SBM diet had the lowest BWG and FI and the highest FCR, as well as the smallest RPM (P <0.05). Both OC and UC expeller SB reduced the mean apparent ileal digestibility (AID) of all non-essential and essential amino acids at d 14 (P <0.05) by 3.8% and 3.2%, respectively. The AID of Lys was 7% lower (P <0.05) in birds fed the OC SBM batch compared to the NC treatment at d14 and 28.The adverse effects of OC expeller SB on BWG were driven by digestible amino acid (AA)intake, which was lower (P<0.05) for Lys, Met+Cys, and Thr in the OC treatment compared tothe NC and the UC treatment groups. In conclusion, these results showed that inappropriate SBprocessing can lead to a lower AA digestibility resulting in lower growth performance andeconomic losses. Extruded soybean results from mechanical extraction of oil from soybeans(SB) (Ravindran et al., 2014). During processing, soybeans are exposed to heat treatment toremove antinutritional factors and to increase the nutritional value of extruder SB for optimalbird growth performance. Variations in SB processing conditions, such as moisture, dryingtime, and toasting and drying temperature, lead to variability in the trypsin inhibitors(TI)amount ingested by poultry between SB batches (Karr-Lilienthal et al., 2004).

I.INTRODUCTION

Both overheating and underheating affect the nutritional value and quality of SB (Karr-Lilienthal et al., 2004). Undercooked SB results in an excessive concentration of antinutritional factors, such as TI, decreasing the intestinal activity of pancreatic proteases. In contrast, excessive heat treatment results in a Maillard reaction that reduces nutrient digestibility (Araba and Dale, 1990). Thus, the objective of this study was to investigate the contributions of poorly processed expeller SB on bird growth performance, amino acid digestibility and intestinal integrity of broiler chickens.

II. METHOD

Male Cobb 500 chicks (1,860) were obtained from the Cobb-Vantress® hatchery (Cleveland, GA, US). Before placing, birds were vaccinated with a commercial coccidia vaccine Coccivac®-B52 (Merck Animal Health, Kenilworth, NJ, U.S.) at The University of Georgia’s Poultry Diagnostic and Research Center (Athens, GA). After vaccination, birds were randomly distributed into 3 treatments (10 replicate pens per treatment; 62 birds per pen) such that mean BW was not different between pens. The treatments from d1 to d35 consisted of a expeller soybean-maize diet with SB processed with different extruder temperatures of 182, 199, and 154 °C for normal-control, overcooked, and undercooked SB, respectively (Perdue Agribusiness LLC). Extruder SB was fed as a fixed inclusion in the diet, which notably varied by CP (dry matter basis) by 50.7, 49.1, and 48.8 % amongst the control, overcooked, and undercooked, respectively. Basal diets consisted of a expeller-SB concentration of 35, 30, and 25% for the starter (1-14d), grower (15-28d), and finisher (29 to 35d) with 0.5% inclusion of titanium dioxide as an indigestible marker. The fixed inclusion of extruded SB during the dietary phases was aimed to reflect processing variations seen when producing commercial diets.

Bird body weight (BW) and feed intake by pen were recorded on d 0, 14, 28, and 35 to evaluate body weight gain (BW gain) and mortality-adjusted feed conversion ratio (FCR). On d 35, five birds per pen were randomly selected and humanely euthanised by carbon dioxide. The weight of the right pectoralis major was recorded after excision, and the relative weights within a pen were determined at 35 d of age. Data were analyzed as one-way ANOVA using JMP software (JMP Software, Cary, NC, U.S.), with the pen as an experimental unit. Tukey’s multiple comparison test was used to compare the significant means (P < 0.05).

III. RESULTS

Intestinal permeability increased in birds fed the OC SBM (P < 0.05). On d 35, birds given the OC SBM diet had the lowest BWG and FI and the highest FCR, as well as the smallest RPM (P < 0.05) (Table 1). Both OC and UC expeller SB reduced the mean apparent ileal digestibility (AID) of all non-essential and essential amino acids at d 14 (P < 0.05) by 3.8% and 3.2%, respectively. The AID of Lys was 7% lower (P < 0.05) in birds fed the OC SBM batch compared to the NC treatment at d14 and 28 (Table 2). The adverse effects of OC expeller SB on BWG were driven by digestible amino acid (A.A) intake, which was lower (P< 0.05) for Lys, Met+Cys, and Thr in the OC treatment compared to the NC and the UC treatment groups (Table 3).

Table 1 - Effects of commercial processing conditions of extruder SB on growth performance and intestinal permeability of broilers.

Table 2 - Effects of commercial processing conditions of extruder SB on apparent ileal digestibility coeficients of amino acids at 14 and 28 days.

Table 3 - Effects of commercial processing conditions of extruder SB on digestible amino acid intake from 0 to 35 days.

IV. DISCUSSION

Varying the extruder temperature of SB batches during processing had a negative impact on protein quality in terms of nutrient density and antinutritional components. Such physicochemical and structural differences observed amongst the three SB batches may disrupt the digestion and absorption of nutrients within the intestine, affecting growth performance, muscle accretion, and intestinal integrity.

Increased serum FITC-d concentration is indicative of paracellular permeability due to inflammation and disruption of the intestinal mucosa barrier (Liu et al., 2021). In this study, birds consuming overcooked SB showed a greater serum FITC-d concentration at d 16. The Maillard reaction products includes glycation end-products, and they are digestion resistant and accumulate in the intestinal mucosa resulting in gut barrier damage and intestinal inflammation (Webster et al., 2005). Thus, the greater FITC-d concentration observed in birds consuming overcooked SB may be related to Maillard reaction products with pro-inflammatory capacity impairing the intestinal barrier function (Oh et al., 2017).

The reduced BW at d35 observed in birds consuming the overcooked SB was significantly correlated with the decreased cumulative amino acid intake observed from d 0 to 35, particularly for Lys, Met, M+C, and Thr. Differences in BWG, FCR, and muscle accretion were likely due to decreased amino acid intake and Maillard reaction, with the lowest bird performance shown in birds consuming overcooked SB (Aburto et al., 1998; Parsons et al., 1992). These findings suggest that both differences in nutritional composition and physical components of expeller SB have robust effects on bird performance, particularly when SB has been overheated.

In conclusion, these findings stress the importance of optimizing a safe extrusion temperature range without penalty of the SB nutrient value and preventing processing and live production costs in field operations. It is necessary to have quality assurance programs on CP quality with appropriate methods to determine poor SB processing conditions in an effective manner.

ACKNOWLEDGEMENTS: We acknowledge Perdue AgriBusiness LLC for providing the commercial expeller SB for this project.

Presented at the 34th Annual Australian Poultry Science Symposium 2023. For information on the next edition, click here.

References

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Karr-Lilienthal LK, Grieshop CM, Merchen NR, Mahan DC & Fahey GC Jr (2004) Journal of the Agricultural and Food Chemistry 52: 6193-6199. https://pubs.acs.org/cgi-bin/abstract.cgi/jafcau/2004/52/i20/abs/jf049795+.html

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