# Taste Preferences in Broilers: Behavioral Evaluation for Varying Concentrations of Four Essential Amino Acids

## TL;DR

This study explores how young chickens respond to different concentrations of four essential amino acids, finding that Lysine at high concentrations is preferred while Threonine and Tryptophan are avoided.

## Contribution

The study introduces a novel behavioral evaluation framework for amino acid preferences in broilers, emphasizing the need for bird-specific feeding behavior assessments.

## Key findings

- Lysine at 1.5% concentration showed higher preference compared to water and other concentrations.
- Threonine and Tryptophan at 1.5% were less preferred than water, confirmed by sensory-motivated intake analysis.
- No palatability differences were observed across amino acid concentrations, possibly due to differences in behavior between chickens and other animal models.

## Abstract

This study examined how chickens respond to essential amino acid solutions. After a one-hour fast, we tested 64 one-day-old male chickens over 16 days, offering them Lysine, Methionine, Threonine, and Tryptophan in concentrations ranging from 0.1% to 1.5% through two-choice preference tests. Amino acid solutions such as Threonine and Tryptophan at 1.5% tended to show less preference than drinking water, which was confirmed in the case of Threonine when performing a sensory-motivated intake (SMI) analysis. However, Lysine (1.5%) numerically showed a higher preference ratified by SMI and acceptability analysis concerning water and other concentrations of the same amino acid, respectively. No palatability differences across amino acid concentrations were observed, which is probably attributed to differences in solution intake behavior between chickens and other animal models such as rats. These findings support the idea that it is essential to standardize feeding behavior assessments in birds based on their feeding patterns and nutritional requirements.

Umami taste compounds are perceived in broilers through taste buds that detect peptides and amino acids, which can positively or negatively affect their feeding behavior. In this study, we evaluated the intake behavior for four essential amino acids (Lysine, Methionine, Threonine, and Tryptophan) in chickens. Sixty-four one-day-old male birds (Ross 308) were used. For 16 days during the early stage of the birds, two-choice preference tests were performed, in which 16 combinations composed of four amino acids in four concentrations (0.1 to 1.5%) diluted in water were evaluated, which were supplied in contrast to the delivery of water (a neutral compound) to a pair of birds in a pen for 4 h of administration after a prior 1 h fast. Amino acid solutions such as Threonine and Tryptophan tended to show less preference at the highest exposed concentrations (1.5%) concerning drinking water, which was confirmed in the case of Threonine when performing a sensory-motivated intake analysis (SMI). The opposite occurred with Lysine (1.5%), which numerically showed a higher preference ratified by SMI and acceptability analysis concerning water and other concentrations of the same amino acid, respectively. When palatability was measured with pecking cluster size, no significant differences across amino acid concentrations were observed, which is probably attributed to short recording periods and differences in solution intake behavior between chickens and previous experimental models such as rats. The results reinforce the notion that it is necessary to standardize feeding behavior tests in birds according to their feeding patterns and nutritional needs.