Feeding behaviour: Understanding the science behind feed palatability

When developing new diets, manufacturers must achieve a balance between nutrition quality and sensory appeal because feed with the high nutritional quality might not be consumed if they have low sensory appeal animals, resulting in a low repeat purchase intention by farmers.

Dr Stéphanie Ladirat
Global R&D Director

The important role of feed palatability in livestock animals, and particularly young animals, is reflected in their sensitivity to the smell and taste of feed, which influences their feeding behaviour. These feeding experiences are dependent on formula, processing, and the freshness and stability of raw materials, making palatability a science demanding discipline and creativity. Various palatants are used in feed to encourage a higher or more consistent feed intake, leading to a more homogenous performance. Indeed, it is of the highest importance to pay attention to the palatability of the compound feed, taking into account ingredients with good or bad palatability and their interaction over the time. When developing new diets, manufacturers must achieve a balance between nutrition quality and sensory appeal because feed with the high nutritional quality might not be consumed if they have low sensory appeal animals, resulting in a low repeat purchase intention by farmers.

For feed manufacturers and nutritionists, palatability can be seen as a concern and an opportunity. Indeed, several factors can play a role and impact positively or negatively the attractivity of feed:
Formulation variations: Feed formulations may vary, some raw materials can be changed, this does usually not impair the nutritional value of feed but might alter its palatability.
Raw material variation: In parallel, even if formulations remain unchanged, raw materials can have a different smell or taste over the time, or be used at different inclusion level, which changes intake
Palatability variation: High level of fats shows a higher risk of oxidation that can create some unpleasant rancid smell and reduce feed consumption. This can also reduce the shelf life of feed.
Low palatability ingredients: Some raw materials can have a positive effect on health and performance of animals but a negative effect on feed taste or smell, and therefore reduce feed intake.

As a consequence, the management of feed palatability can greatly contribute to few objectives:
• Ensure a consistent taste and smell of feed, also in the case of reformulation or feed optimization
• Guarantee an optimal feed consumption of animals, also during stress or transition periods
• Preserve the quality of feed and create an olfactory footprint for customers

While palatability can be of great interest for feed producers, it is difficult to predict the future response of animals. The perception will vary, depending on the species, the environment and the application. Not all animals have the same taste or smell receptors (Karo, 1966), and thus, not all animals will have the same sensibility, or show the same preference. To take into account this variability, different strategies have been investigated, based on chemical analyses, sensorial analyses or field evaluations. At the end of the day, the different approaches are useful to build a comprehensive understanding and propose the best option to secure optimal consumption for the animals in every case. Olfactory cues play an important role in influencing acceptance of the product from the animal and the farmer. Since food-evoked emotions (these last years) have been found to play an important role in consumer acceptability and purchasing-related behavior the feed industry should also consider farmer’s emotional responses to feed. In a recent test (See figure 1), a team of panelists evaluated samples of flavours from different suppliers through a blind ranking test. Each flavour was diluted in a carrier and dosed to have an equivalent cost per ton of feed. Later, the same flavours were evaluated in pelletized feed, still based on the same dose. All flavors had a red fruits profile. The different tests have shown differences of intensity when products were applied in feed at different conditions: All products have pleasant fruity smell with different additional notes but product A showed the highest intensity, products B, D, H showed the lowest one, especially after pelletization. The comparison based on cost per ton of feed and flavour intensity showed substantial differences between products, in term of return on investment.

Nevertheless, evaluation of flavors with human panelists might not be enough to measure differences. Due to an innate survival mechanism for avoiding the over-consumption of toxic plants, horses are naturally sensitive and described as “fussy eaters” (Provenza, 1988). Thus, a panel of horses can be helpful to evaluate feed palatability. In a recent trial (See figures 2), a panel of horses was used to evaluate the palatability of different ingredients. The objective was to determine the impact of each ingredient to improve or damage the palatability of feed. In that test, animals were exposed to regular feed (Negative control NC) or feed supplemented with one ingredient (Positive control PC) for 5 minutes. Ingredients were tested in a random order for every participant. Preference was measured for every test as well as Intake. Some ingredients reduced the attractivity of feed, while others such as apple or fenugreek flavors had limited effects. Finally, red fruits, vanilla or fresh flavors had a positive effect on preference and intake.

As a matter of fact, it is difficult to provide accurate guidelines for every situation. In that respect, it is important to work with multiple points of references, good analytical feedbacks from lab and, last but not least, practical experiences from the field. Finally, it is critical to consider not only the effect of each ingredient but the overall palatability of formulation. Previously, Fathi et al. evaluated the effects of a vanilla flavour in starter feeds on pre-weaning and post-weaning calf performance. The trial showed that calves fed flavored starter weighed more at the weaning and at the end of the experiment. Moreover, the pre-weaning average daily gains increased significantly (+21%, p<0.03). Something that is also confirmed with practical experiences in the field. Preference tests under field conditions with young calves showed that flavours such as ‘milky-vanilla’ or ‘caramel-biscuit’ could increase the palatability and the therefore the consumption of compound concentrate feeds. Other solutions have been developed to impact both smell and taste of the feed, for intense to cover the negative effect of certain ingredients, with intense fruity or fresh flavors. Finally, some more solutions, with ‘caramel-molasse’ profile, have also show high efficacy to bring a consistent, homogeneous and long-lasting palatability to feed. Calves that start eating quickly will be exposed to less stress, will be less susceptible to getting sick and will perform better. Anything that encourages the calves onto their early weaner grain ration is positive. Ideally, the same flavour, before and after weaning, can be beneficial particularly for very young and fragile calves.

Palatants have always been important additives in young animal nutrition, both for marketing (to differentiate) and technical purposes (to secure feed consumption and early performance). Recent research has confirmed that young animals are effectively reacting on flavors and/or taste enhancers in specific production systems, offering in the end a positive return on investment for the producer. Besides, more than ever, nutritionists and formulators have got more challenges about raw materials, that fluctuate both in terms of quantity, price and quality. To meet these objectives, high quality palatants can help the nutritionists and feed formulators to optimise their feed formulation with more confidence in the challenging situations. Using the right palatant solution will help to offer consistent quality to customers and guarantee early performance of animals.