Precision Feeding of Poultry: Matching Nutrient Supply to the Nutrient Requirements of Individual Birds

Introduction

Academia and industry have invested huge resources into defining both the nutrient composition of feedstuffs and nutrient requirements of meat and egg-type poultry. Both aspects are highly complex because of their dynamic nature. Nutrient availabilities depend on the genetics of each feedstuff, but also geographic region, weather, and growing conditions. These factors impact both the quantity of nutrients and the molecular structures from which those nutrients must be extracted by animals after consuming the feed (reviewed by Gutiérrez-Alamo et al., 2008). Furthermore, the molecular context of each feed ingredient and nutrient balance can impact nutrient availability. Nutrient requirements of individual animals also vary due to genetics, age, stage of production and environmental factors such as temperature, lighting programs, health status, and even feeding level. Together, these sources of variation pose a great challenge for providing the right nutrients to the right birds at the right time. We must have a solid understanding of the available nutrient content feed and the nutrient requirements of animals in order to match them.

Figure 1. Theoretical flock-level broiler nutrient requirements (purple line), nutrient levels provided by a 3-phase feeding program (green line), and inefficiencies due to excess nutrients (salmon shaded areas) and unrealized growth potential (red shaded areas).

Take Phase Feeding to its Logical Conclusion

Phase names such as pre-starter, starter, grower, developer, finisher, pre-lay, and lay diets are familiar to all nutritionists. Phase feeding is defined as the feeding of several diets, each for a short period of time to roughly meet age-specific nutrient requirements (Figure 1). The point of these diets is to provide approximately the right balance of protein and energy, amino acids, and other nutrients for the birds’ age and stage of production. This allows birds to achieve their performance potential while reducing imbalances and excesses that lead to waste. Wasted nutrients are both an economic and an environmental problem.

The number of phases provided is governed by practical considerations. Most barns have limited numbers of feed bins, and the solution has been to deliver a practical quantity to minimize trucking costs, feed the diet until it is depleted, and fill the bin with the next phase diet. Over the years, more phases have been added to reduce nutrient overfeeding. I invite you to suspend the question “How?” for a moment to allow yourself to appreciate the next thought. If you take this phase feeding concept to its logical conclusion, the ideal feeding program to perfectly match nutrient supply in the feed to meet the nutrient requirements of each individual in the flock would be to adjust the feed composition slightly at every meal. Since birds have different temperaments and grow at different rates, measuring these in real-time would help to inform what the diet composition should be. Repeated measures on individual birds would further inform how they have responded to the nutrients provided previously. Further adjustments could then be made to optimize the formulation to accommodate different nutrient requirements of individual animals.

In practice, some farms have installed feed blending systems that allow them to blend 2 diets. Since the ratio of most nutrients to energy decreases as birds grow, a high nutrient:energy diet can be blended at decreasing ratios with a low nutrient:energy diet over time as the birds grow. Simulation modeling comparing a 3-phase feeding program to a flock-level blending concept demonstrated a reduction in nutrient overfeeding, and a slight reduction in unrealized growth potential. Applying this same concept at an individual bird level suggests that substantial further improvements are possible.

Split Feeding Strategies for Laying Birds

Split feeding can be thought of as a within-day approach to phase feeding. It is a concept that has been used for laying hens. The egg formation process causes highly variable nutritional demands throughout each 24-hour period (Keshavarz, 1998). This process was nicely described and elegantly modeled by Kebreab et al. (2009). Hens typically lay their eggs early in the day, and ovulate shortly thereafter. Whereas yolk is deposited into ovarian follicles on a more or less continuous basis, albumen and shell deposition occur at specific times in a daily pattern. Shell formation, in particular, causes large diurnal fluctuations in Ca requirements. It takes several hours for the egg to be formed to the point where shell is deposited in the shell gland. Until that time, there is no demand for Ca from the bloodstream for eggshell formation. By evening, however, and throughout the night, the Ca demand for eggshell formation increases sharply. Unfortunately, this does not coincide with dietary Ca intake. If Ca is not available from the bloodstream, Ca is mobilized from the skeleton. Since Ca is complexed with P in the bone, this P is also mobilized, but it is in over-supply, and since it cannot be used, it is excreted, with detrimental environmental and cost consequences.

Various strategies have been proposed to enable laying hens to use dietary rather than skeletal Ca. Attempts to increase eggshell quality and minimize bone Ca mobilization include feeding coarse or large particle size Ca (Saunders-Blades et al., 2009; Molnar et al., 2017), midnight feeding (Harms et al., 1996; Lichovnikova, 2007), intermittent lighting programs (Balnave and Muheereza, 1997), and split feeding (Keshavarz, 1998; Molnar et al., 2017; Molnár et al., 2018). Although there are costs associated with storage of multiple feeds and management of a more complex feeding program, the egg quality and profitability benefits are making the concept of split feeding increasingly popular, as a form of within-day phase feeding.

Precision Feeding System for Poultry

Precision feeding (PF) is defined as providing the right amount of the right feed to the right animal at the right time to achieve a desired objective. A well-defined desired outcome dictates the composition and/or quantity of feed required to move an individual from its current state to a preferred state. Sensors inform the system of its current state. A science-based model can be used to estimate what nutrients, if any, should be fed to achieve the desired outcome.

Finally, a machine automatically implements the feeding decision to move the animal from its current state closer to the desired outcome. Recently, my team developed a PF system for controlling feed intake and monitoring BW and feed intake of free-run chickens. Prior systems could monitor feed intake or BW or both. However, our PF system is able to control feed intake. This was a critical technological step toward precision feeding. We have fed broiler breeders the precise quantity of feed required to achieve the desired BW, and have consistently grown group-housed broiler breeders with a BW CV of under 2% at the time of photostimulation (van der Klein et al., 2018a; van der Klein et al., 2018b; Zuidhof, 2018). This was done by measuring each broiler breeder’s BW in real-time, and then allowing access to feed only when the birds weighed less than the target BW. We are beginning our first research trial with a new feeding station that allows us to provide a variety of different diets (Figure 2). We will begin by characterizing and modeling the responses of individual birds to a variety of diets with the goal of improving nutrient response models. Ultimately, this new PF system and others like it will be used to provide specific diets based on the attributes of each bird that are measures upon entry.

Figure 2. This second generation precision feeding station controls access to different feeds.

Conclusion

The nutritionist’s goal of matching nutrient supply with nutrient requirements at every meal is complex. A lot of data, knowledge, and technology is required. With sensors, however we can detect the current state of the animals within their environment and available nutrient content of feeds. With good models, we can determine the balance of nutrients required by the animal. With real-time NIR, we can have a pretty good idea of the available nutrient content of feeds and feedstuffs. With the right machines, we can deliver those nutrients to the right bird in real-time. The big data collected in such systems can be used directly to facilitate further improvement and refinement because responses that could formerly only be measured in labour intensive research studies will be collected automatically. By reducing the duration of phase diets to one meal at a time, we will reduce feeding of excess nutrients, and thus reduce excretion of N, P, and CO₂ to the environment, and eliminate the costs associated with providing nutrients in excess. There is good reason to believe that the cost of technology will come down as it has for electronics in general. Precision feeding of poultry may be closer to becoming reality than you think.

Presented at the 2021 Animal Nutrition Conference of Canada. For information on the next edition, click here.