What question did this study set out to answer?

The research aims to evaluate how different protease tolerances to pelleting affect growth and amino acid digestibility in broiler chickens.

June 12, 2026Open Access

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Protease Highly Resistant to Pelleting Improves Amino Acid Digestibility in Broiler Chickens on Pellet Form of Feed

XLXuetao LiuChinese Academy of Agricultural Sciences SJSongjun JiaoChinese Academy of Agricultural Sciences YZYing ZhangChinese Academy of Agricultural Sciences

Key Points

The research aims to evaluate how different protease tolerances to pelleting affect growth and amino acid digestibility in broiler chickens.
Screened 13 serine-type proteases for activity loss during cold pelleting.
Conducted a 5 × 2 factorial feeding trial with normal and low-protein diets supplemented with varying proteases.
Assessed growth performance and standardized ileal amino acid digestibility over 14 days.
Pellet feed increased average daily gain (ADG) and feed intake (P < 0.01) but decreased crude protein (CP) digestibility (P < 0.01).
Low-tolerance proteases showed significant benefits for amino acid digestibility in mash feeds, while moderate and high-tolerance proteases were beneficial in pellet feeds.
Significant regression differences indicated enhanced SID benefits correlating with the specific diet form (mash vs. pellet).

Abstract

ABSTRACT Exogenous proteases improve amino acid utilization in broilers, yet enzyme inactivation during feed manufacturing hinders their practical applications in poultry production. This study was conducted to investigate growth performance and nutrient digestibility responses to protease varying in tolerance to pelleting in broiler chicks. Thirteen serine-type proteases were screened for activity loss using the cold pelleting technique without steam conditioning. Three proteases showing low-tolerance (46.6% of activity loss), moderate-tolerance (29.2% of activity loss) and high-tolerance (12.5% of activity loss) to pelleting were selected for a 5 × 2 factorial feeding trial. The five experimental diets, including normal-protein control ( NPC ), low-protein control ( LPC ), and LPC supplemented with protease with low-, moderate- or high-tolerance to pelleting, were provided to day-old chicks as either mash or pellet feed for 14 days. No significant diet × feed form interactions were observed for growth performance, nutrients digestion or standardized ileal amino acids digestibility ( SID ). Compared with mash feed, pellet feed increased ADG ( P 0.05). Despite of no interaction between diet × feed form on SID, the magnitude of protease-induced SID improved negatively correlated with the inherent SID of basal diet ( P < 0.05). Regression analyses revealed that low-tolerance protease exerted greater SID benefits in mash diet, whereas proteases with moderate and high tolerance exerted greater SID benefits in pellet diet, as evidenced by the significant differences in regression slope (mash, P = 0.186; pellet, P = 0.002) and intercept (mash, P < 0.001). In conclusion, pelleting improved the growth performance but reduced protein and AA digestion in broiler chicks. In the low-protein regimens, proteases with moderate and high tolerance to pelleting effectively restored growth performance and AA digestibility in pellet feed.

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Cite This Study

Liu et al. (Mon,) studied this question.

synapsesocial.com/papers/6a2ba4208101cf8926f02a73 https://doi.org/https://doi.org/10.1016/j.psj.2026.107257

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