Neopobia in poultry: the influence of sensory stimuli on feeding behavior and productivity
Understanding how poultry perceive feed is essential for optimizing feeding programs. Discover the science behind neophobia, feed color discrimination, and practical feeding solutions.
Neophobia is a behavioral response of animals to novel or unfamiliar stimuli, manifested as hesitation or refusal to interact with a new object or food source. In birds, neophobia is an important adaptive trait that evolved as a mechanism to avoid potentially harmful feeds (Jones, 1987). However, under commercial poultry production conditions, this response may have negative production consequences, as diet composition, physical form, or visual appearance of compound feeds frequently changes.
In modern broiler and pullet rearing systems, transitions between feeding phases are accompanied by changes in formulation, structure, particle size, and sometimes feed color, which may provoke short-term neophobic responses and reduced feed intake.
In modern broiler and pullet rearing systems, transitions between feeding phases are accompanied by changes in formulation, structure, particle size, and sometimes feed color, which may provoke short-term neophobic responses and reduced feed intake.
Sensory mechanisms and color perception in poultry
Birds possess a highly developed visual system with tetrachromatic vision and the ability to perceive ultraviolet radiation (approximately 350–780 nm), significantly expanding their spectral range compared to humans (Bennett & Cuthill, 1994). This feature enables efficient discrimination of feed color, surface texture, and light reflections.
The gustatory system of chickens is characterized by a lower number of taste buds compared to mammals; however, their functional density within the oral cavity is sufficient to recognize major taste modalities (Cheled-Shoval et al., 2017). Unlike mammals, birds lack large salivary glands; instead, they possess numerous small mucous glands located in the palate and tongue. These glands produce a mucinous secretion that facilitates dissolution of feed particles and activation of taste receptors.
Therefore, primary feed evaluation in poultry occurs predominantly at the visual level, while gustatory mechanisms are activated after feed contact with the oral mucosa.
The gustatory system of chickens is characterized by a lower number of taste buds compared to mammals; however, their functional density within the oral cavity is sufficient to recognize major taste modalities (Cheled-Shoval et al., 2017). Unlike mammals, birds lack large salivary glands; instead, they possess numerous small mucous glands located in the palate and tongue. These glands produce a mucinous secretion that facilitates dissolution of feed particles and activation of taste receptors.
Therefore, primary feed evaluation in poultry occurs predominantly at the visual level, while gustatory mechanisms are activated after feed contact with the oral mucosa.
Neophobia during feed changes: behavioral and economic implications
Changes in feed color or appearance may induce short-term neophobic responses characterized by reduced feed intake, increased alertness, and exploratory behavior (Jones, 1987). Under production conditions, this may result in:
While controlled experimental conditions often show minimal effects of feed color on productivity, commercial environments may amplify neophobic responses due to concurrent stressors such as stocking density, lighting, and management practices.
- Temporary reduction in average daily feed intake;
- Fluctuations in body weight gain;
- Impaired feed conversion ratio;
- Increased pecking or litter exploration activity.
While controlled experimental conditions often show minimal effects of feed color on productivity, commercial environments may amplify neophobic responses due to concurrent stressors such as stocking density, lighting, and management practices.
Experimental evidence on the effect of feed color on poultry response
Findings of Gulizia and Downs (2021).
Gulizia and Downs (2021) evaluated the effects of artificially colored feed (red, green, blue, yellow, orange, and purple) on broiler performance between days 1 and 21. The authors reported that:
These findings suggest that feed color alone is not a determining factor of productivity in the absence of additional stressors.
Findings of Vargas et al. (2023)
In the study by Vargas et al. (2023), a feed color preference test was conducted during the starter phase. Broilers were simultaneously offered standard and colored feeds. The authors observed that:
These data confirm the presence of neophobic elements toward unfamiliar coloration, even when the nutritional value remains unchanged.
In this context, neophobia should not be interpreted solely as a negative trait, but rather as a protective mechanism that becomes problematic only under intensive production conditions.
Gulizia and Downs (2021) evaluated the effects of artificially colored feed (red, green, blue, yellow, orange, and purple) on broiler performance between days 1 and 21. The authors reported that:
- Broiler chicks were able to discriminate between different feed colors;
- Blue and purple diets showed a slight tendency toward improved weight gain;
- Overall feed intake and feed conversion ratio did not differ significantly among treatments.
These findings suggest that feed color alone is not a determining factor of productivity in the absence of additional stressors.
Findings of Vargas et al. (2023)
In the study by Vargas et al. (2023), a feed color preference test was conducted during the starter phase. Broilers were simultaneously offered standard and colored feeds. The authors observed that:
- Birds preferred the standard (non-colored) feed;
- Blue and purple variants were consumed in lower amounts;
- Mortality and physiological indicators were not affected.
These data confirm the presence of neophobic elements toward unfamiliar coloration, even when the nutritional value remains unchanged.
In this context, neophobia should not be interpreted solely as a negative trait, but rather as a protective mechanism that becomes problematic only under intensive production conditions.
Sensory memory and behavioral aspects of neophobia
Birds are capable of forming sensory memory associated with feed characteristics (Jones, 1987). Previous exposure to a specific type of feed reduces the intensity of neophobic responses when a similar product is reintroduced.
Consequently, gradual dietary transitions (feed blending strategies) may serve as an effective approach to minimize stress associated with formulation changes.
Consequently, gradual dietary transitions (feed blending strategies) may serve as an effective approach to minimize stress associated with formulation changes.
Practical implications for feeding management
To reduce manifestations of neophobia under commercial conditions, it is advisable to:
Particular attention should be paid to the starter phase, during which behavioral reactivity of birds is most pronounced.
- Avoid abrupt changes in physical feed characteristics;
- Implement gradual transitions between feeding phases;
- Control particle size distribution and pellet structure;
- Maintain sensory consistency when introducing new ingredients.
Particular attention should be paid to the starter phase, during which behavioral reactivity of birds is most pronounced.
Conclusion
Neophobia in poultry is an adaptive behavioral mechanism that may influence feed intake and productivity. Visual stimuli, particularly feed color, play a significant role in primary feed evaluation. Experimental evidence suggests that changes in feed color do not necessarily affect productivity but may alter consumption preferences.
Understanding the sensory biology of poultry is an essential component of feeding optimization and reducing the risk of short-term declines in feed intake.
Understanding the sensory biology of poultry is an essential component of feeding optimization and reducing the risk of short-term declines in feed intake.
References
- Bennett, A. T. D., & Cuthill, I. C. (1994). Ultraviolet vision in birds: What is its function? Vision Research, 34(11), 1471–1478.
- Cheled-Shoval, S. L., Druyan, S., Uni, Z., & Shinder, D. (2017). Bitter, sweet and umami taste receptors and downstream signaling effectors: Expression in embryonic and growing chicken gastrointestinal tract. Poultry Science, 96(9), 3180–3191.
- Gulizia, J. P., & Downs, K. M. (2021). The effects of feed color on broiler performance between day 1 and 21. Journal of Applied Poultry Research, 30(2), 100159.
- Jones, R. B. (1987). The assessment of fear in the domestic fowl. Applied Animal Behaviour Science, 17(1–2), 35–47.
- Vargas, L., et al. (2023). Assessing feed color preference of broilers during the starter phase. Poultry, 4(1), 2.
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