High and sustained peak egg production can only be achieved with uniform breeder flocks fed to meet their nutritional requirements. With 85-88% peaks now possible in the industry, it is obvious that we have to carefully plan and execute a feeding program tailored to meet the breeders' nutrient needs. Underfeeding results in very short duration peaks, of only 3-4 weeks, and those are usually associated with the classical sign of loss or stall-out in body weight for 1-2 weeks. On the other hand overfeeding, especially with energy, will result in excessive weight gain, and while peak production may be little affected, there will be precipitous loss in egg production through 34-64 weeks of age. The basis of feed allocation at this critical time is obviously to allow genetic potential for increases in both egg numbers and egg size, and also to allow for modest weekly gains in body weight. Managers should consider "challenge feeding" as part of their feed management system at this critical time.
Challenge feeding involves giving the hens extra feed on 2 or 3 days each week, based on need, without changing the base feed quantity scheduled for the flock. For example, a flock may receive 168 g/bird/day at peak, with an additional "challenge" of 7 g/bird/day given three days each week. The challenge feed is, therefore, equivalent to 3 x 7g / 7d = 3 g/bird/day. In reality birds receive the equivalent of 168 g + 3g = 171 g/bird/day. The immediate question is why bother with this more complicated system, and just give the flock a base feed allowance of 171 g/bird/day?
The advantages of challenge feeding, rather than simply increasing the base allocation are:
The actual quantity and timing of challenge feeds must be flexible if they are to be used efficiently. In practice the challenge should not represent more than 5% of total feed intake, and most often the quantity will be 2-4%. On the other hand, the quantity of the challenge should be large enough to meaningfully contribute to the factors listed previously. For this reason there needs to be a balance between the quantity of feed given, and the frequency of this feeding. For example, a daily challenge of 3 g/bird/day given daily will be much less effective than 7 g/bird/day given 3 times each week. In both instances birds are receiving 21 g/week as a challenge, but in the later example the challenge quantity is more meaningful and we are more likely to see a bird response in terms of egg output.
Challenge feeding should start when birds are at 60-70% production, and should be discontinued when egg production falls below 80%. For most flocks, therefore, we can expect to practice challenge feeding from about 29 through 40 weeks of age. The idea of challenge feeding is to more closely tailor feed allocation to breeder hen needs, and so there should be no standardized system. Managers must be given flexibility to alter challenge feeding based on fluctuating needs. In most instances the challenge will be used to lead bids into a sustained peak. Because the concept of challenge feeding is to more closely tailor feed allocation to needs, then it is usual practice to alter the quantity and/or duration of challenge as birds progress through peak egg production. Maximum challenge feeding should coincide with peak egg output, with lesser quantities given prior to, and after actual peak. On this basis we recommend challenge feeding to be reduced (but not discontinued) once birds are 2% below peak egg production. Following are three examples of challenge feeding tailored to three different flock situations.
Flock #1. High nutrient dense feed used, with good ingredient quality control. Expected high-low temperatures of 31-24 degrees Celsius. Good flock uniformity at 20 weeks of age, and previous flocks show consistent peaks of 85-87%.
In this example, because birds are uniform in both weight and maturity and a good quality diet is used, and there is no major temperature stress, the challenge is quite mild. For this flock, a heavier challenge may result in excess weight gain. This type of mild challenge is most frequently used where feed quality is ideal, and there is minimal disease and mycotoxin exposure.
Flock #2. High nutrient-dense feed used, with good ingredient quality control. Expected high-low temperatures 28-14 degrees Celsius. Poor to average flock uniformity at 20 weeks of age, and previous flocks show variable peaks of 81-87%.
For this flock we are giving a larger challenge feed, because night-time temperature is quite low and there is a problem with maturity related to poorer uniformity. On average this flock may gain a little more weight than example Flock #1, and this will have to be accommodated with a more vigorous post-peak feed withdrawal program.
Flock #3. Low nutrient dense feed used, with poor ingredient quality control, and so feed composition may be variable. Expected high-low temperatures 28-20 degrees Celsius. Average to good flock uniformity at 20 weeks of age, and past flocks show variable peaks at 80-86%.
For this flock, base feed allowance is increased because a low nutrient dense feed is used, and challenge is fairly aggressive again due to concern over feed quality and poor uniformity.
*In these examples it is assumed that managers will continue to maintain breeder body weight through peak, and make necessary adjustments to the challenge if over-or under-weight conditions are seen.
Challenge feeding can also be used post-peak if there are precipitous declines in egg production related to minor disease challenge or management or environmental stress. Under these conditions, challenges of 10 g/bird/day for two consecutive days are recommended. If no immediate response is seen in egg production, then challenge should be discontinued. If egg production returns to normal, then the challenge should gradually be reduced over the next 2-3 days.
Challenge feeding allows tailoring of feed allocation to suit individual flock needs. Managers should be flexible in actual allocations, although maximum challenge feed allocation needs to coincide with peak egg production. Breeders will respond to a good challenge program, with sustained peak production and better post-peak persistency. On the other hand, the challenge should not usually represent more than 5% of total feed intake, because excessive challenge will invariably result in obesity and related loss in post-peak performance.
In general, when birds are subjected to such stresses as variable feed quality, mycotoxin challenge and/or fluctuating or extreme environmental temperature, then a high base feed allowance, coupled with aggressive feed challenge, is recommended. On the other hand, lower feed inputs are possible where consistent quality high-energy feeds are used, and where there is good environmental control.
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