An innovation for managing broiler breeder pullets: precision feeding

Martin J. ZuidhofMartin J. Zuidhof

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Body weight (BW) remains the single most important factor in breeder management, but not just average BW. A flock with a high BW uniformity and stable metabolism is the primary goal. Consistent average daily gains are just as important as achieving the target BW. A uniform flock of birds that has achieved the BW target in a smooth and steady fashion is in the best position to produce the most high quality chicks. Feeding management, including time between meals, feeder space, grading, and ultimately precision feeding will help increase broiler chick numbers. Precision feeding –providing the right feed to the right bird at the right time –is a revolutionary idea for broiler breeder management. It takes the guesswork out of managing breeders by directly measuring AND responding to the most important variable at the individual animal level.

Precision Agriculture, and Precision Livestock Farming are based on simple but solid principles. First, there must be variation in a trait that is important for success. That trait must be measurable. Finally, you must be able to modify your management based on the value of the trait. In broiler breeders, the trait is body weight. There is a lot of unwanted BW variation, which reduces reproductive efficiency. Body weight can be measured, and we can also make a choice to provide feed or not to provide feed based on the body weight of any bird at any time. The bottom line is that we can therefore apply these principles to the major body weight uniformity problem that exists in the broiler hatching egg industry.

A Precision Feeding System has been developed at the University of Alberta to solve the problem of BW variation in broiler breeders.

Since the 1940s, selection for high growth rates, efficiency, and yield in broilers has allowed the poultry industry to enjoy many intended benefits. Growth rates from 1957 to 2005 increased at a compounded rate of 3.3% per year, yielding 80% more pectoralis major, while requiring half the total feed. There have also been unintended consequences, and a prime example is the challenge of allocating feed to parent stocks, which is faced daily by hatching egg producers. Allowed to express their genetic potential for growth, broiler breeder reproduction and welfare is compromised. Overweight hens produce excess follicles on their ovary. Their reproductive output is seriously compromised in terms of settable egg numbers, fertility, and chick quality. To optimize chick production we practice feed restriction. In the last 30 years, there has been little change in the target BW profiles of breeder hens. Because their progeny have continually increasing growth potential, the relative severity of restriction of breeders is constantly increasing. As feed allowance becomes more limited relative to growth potential, competition for feed increases each year, and aggressive pullets out-compete passive ones in the feeding rush. This leads to low flock uniformity. Flock uniformity is a spiralling management issue. It is difficult to allocate the correct amount of feed to a non-uniform flock because the birds have unequal nutrient requirements.

Biological thresholds for puberty
There are at least 4 thresholds that a broiler breeder pullet must cross to become sexually mature: age (related to hypothalamic maturity), carcass fatness, BW, and day-length. If any pullet has not reached one of these thresholds, it cannot lay eggs. For example, if a broiler breeder female is under the threshold of (approximately) 2 kg, it cannot undergo sexual development. The greater the body weight variation in a flock of pullets, the higher the percentage of birds in the flock that are not ready for photo-stimulation. Non-uniform flocks have therefore benefitted from delaying photo-stimulation. Essentially, delaying photo-stimulation acts to hold back birds that have crossed all the other thresholds and are ready to start laying eggs. Once all the birds in the flock have reached all the other thresholds, increasing the light threshold results in all of the birds to responding simultaneously. This is ideal for peak production because the birds all enter lay simultaneously. It is also good for persistence of lay because the nutrients provided to the birds are all used to respond to increasing nutrient requirements for oviduct, ovary, and follicle development. In a uniform flock, no birds are overfed during properly timed pre-peak feed increases because all birds need higher nutrient intake to support their reproductive development.

Feed allocation –who cares?
Feed allocation has become the ultimate obsession of hatching egg producers, and for very good reason. Restriction of feed intake is the major tool to control body weight gains. In conventional systems, the importance that feed allocation has taken is almost a distraction. Feed allocation is really of secondary importance. What if we could forget about feed allocation and just focus on BW? After all, BW control is what we really want! What would it take? What if the amount of feed we fed broiler breeders was just something we measured as a by-product of the real business of achieving the correct BW? The secret to from the tyranny of the feed allocation decision lies in shortening the amount of time that elapses between decisions about whether or not to feed, and how much. The secret lies in direct and frequent measurements of what really matters which is BW.

Precision feeding
Precision feeding takes the guess work out of allocating feed. Precision feeding is about providing the right amount of feed to the right bird at the right time. The precision broiler breeder feeding system developed at the University of Alberta is a sequential feeding system that considers whether one bird at a time qualifies for feed. If the bird that enters the system is equal to or heavier than the target BW for that exact age (we interpolate target eat to be at the target BW, and it is ejected from the system. If the bird weighs less than the target BW, we grant it access to a small amount of feed for a short duration of time, and then eject it. When it leaves the station, the bird may still weigh less than the target BW, but it would be closer to the target. On its next visit, it would have another chance to eat, and be closer yet to the target BW. The system works very well for feed restricted animals because they are highly motivated (by hunger) to gain access to the system. When the system reliably ejects birds that do not qualify for a meal, the system can quickly process a large number of birds.

Worry less
Things that seemed so complex and important to understand are handled in such a simple and robust way by the precision feeding system that the things you need to worry about in a conventional feeding system no longer need to be worried about. The main objective when feeding broiler breeders is: Donot let the metabolism know you have changed the feed allocation”. In other words, steady energy balance. Do not change things too quickly. Meet the maintenance and egg production requirements as closely as possible, with an ever-so-small excess which the birds will partition toward growth. Avoid over-correcting feed allocations, which results-feeding frog or a when bull-whip birds volunteer to effect weigh themselves. Multiple times a day, and only receive a small amount of feed, when they are less than the target BW, this process becomes automatic. If the weather changes, and the birds need extra feed for maintenance, the birds just qualify for feed a little quicker than if the weather were warm. If the birds are more active, they need a little more feed to maintain their weight. No problem one or two extra successful visits to the station.

If precision feeding is carried over into the laying phase, even more benefits accrue. Precision feeding supports egg laying hens by providing the nutrients needed to replace the nutrients deposited into the egg. Laying eggs at a high rate? No problem. If the hen loses 60 g because she laid an egg, she automatically qualifies for that amount of feed because her BW dropped. If a hen stops laying eggs she will remain in a slightly positive energy balance, gaining weight at the target rate of a few grams per week, rather than being allowed to become obese. This will increase her chances of coming back into lay.

Practical advice for conventional feed allocation
If you don’t a precision I still have some feeding practical advice for system you.
Use BW gain as an indicator of BWa gain bird’s is a much metab more sensitive measure of a Maintenance bird’s of the energy body is the first thing energy gets used for. BW gain is therefore an indicator of the amount of energy available above the requirements for maintenance and egg production under current growing conditions at the current feed allocation. Try to maintain a steady positive energy balance so the birds grow a steady (target) amount every day. Do this by adjusting the feed intake slightly to move the current average daily gain to match what the average daily gain needs to reach the target BW over the next 7 to 10 days.

Weigh birds frequently. This allows you as a manager to benefit immediately from knowledge of how your decision affected the flock. The shorter the time delay in feed back your loop’ the quicker corrections can be applied. Frequent weighing prevents costly over-corrections, and yields a steady growth rate.
Consider the weather. Healthy broiler breeders take care of their maintenance requirements first, followed by egg production. A very small proportion of nutrient intake (5 to 20%) actually goes to BW gain. During the pullet phase in particular, a small (5%) reduction in maintenance requirement from optimal environmental temperatures can double growth rate; conversely an increase in maintenance requirement can completely eliminate the expected growth.
Maximize BW uniformity. Grading, or sorting birds groups based on BW is a good strategy for increasing uniformity. If it is not practical because of labour costs, at least segregate the smallest birds and feed them more until they become ‘more This average’ can be done by providing more feeder space in a sick pen or area, where the smaller birds are placed, or by supplementing their feed intake by using extra feeders. The highest economic benefit comes from boosting the performance of underweight birds.