Sep 18, 2013
Key principles of Feeding Broiler Breeders:
The various elements found on the breeder production graphs need to be read in conjunction with one another. Namely body weight, egg weight, egg production and feeding levels. Looking and managing only a few parameters and not ALL leads to incorrect assumptions and poor decision making going forward.
The weight curve (growth curve) and trend is critical and non-negotiable and all attempts need to be made to follow these weekly requirements. Weighing of birds in rear is the only measure of rearing performance we can reasonably manage and must be as accurate as possible. All attempts must be made to ensure that weighing truly represents the flock. An error here will result in incorrect feed allocations and ultimately poor flock performance. In real terms we should be measuring shank length, which is a far more accurate measure of growth rate, but is unfortunately tedious and is therefore seldom practised.
If one can achieve a uniform flock with a low CV, at the critical age of 10 weeks, in most likelyhood one will have achieved a flock with a uniform carcass as measured by weight and not shank length. The lower the CV, and the closer the mean weight of the flock is to the actual breed trend, the better the performance of the flocks will be. Feeder space and feed availability (feeding management) is the most important aspect of rearing management together with accurate sample weighing. The better the feeding managenent, the lower the CV and the better the production levels. A poor flock CV will lead to reduced peak productions and reduced total egg numbers.
The feeding line is a recommendation and all things being equal one hopes that this feeding level will provide adequate nutrients for the birds to follow the weight curve. Housing type, feed formulations, environmental factors, disease loading and feed management will affect the actual feeding level so it cannot be an exact figure. Feed consumed by the pullet is allocated as follows:
- Pullet maintenance
- Pullet growth (measured by weighing the pullet or carcass development)
Feed consumed by the hen is allocated as follows:
- Hen maintenance
- Hen growth (measured by body weight)
- Egg production/egg (measured by production as a percentage of hen day numbers)
- Egg weight
Grade only if the CV rises above 12%. If grading is going to have any benefit on a flock’s uniformity (CV), it is important to grade by 5 weeks. This will allow a further 5 weeks for corrective feeding in order to obtain the ideal weight as recommended by the breed standard, by 10 weeks of age. A hen has developed 85% of her potential frame size by 10 weeks. By 10 weeks the pullet’s end growth rate is determined. In other words, a pullet above the growth curve at 10 weeks, needs to be maintained on the new trend line but reach 20 weeks at a similar % above the recommended weight profile. If one tries to bring her weight back to the recommended trend line she will be large framed but have minimal muscling and body reserves. This will be detrimental to her ability to maximse her peak and post peak production.
Conversely, if the body weight is below the recommended weight curve at 10 weeks (as often seen is grade out groups), the new growth or weight profile should parallel the actual by a similar percentage below the trend curve. If you try and get pullets back to the line, you end up with small framed pullets that carry extra fat. This is equally undesirable.
Pullets in rear are over graded. Grade at 5 weeks only and then only if required to, due to a high CV. Repeat grading leads to nutritional planes changing as the pullet is moved from a light to a heavy group and back again. Nutrients yo-yo and this is physiologically upsetting on the pullet’s development. Late grading will produce poor weigh profiles and poor CVs that lead to poor peaks. In real terms, evaluation of a flock that is graded late will show poor uniformity. Feeding in rear is aimed at achieving breed weight requirements with a low CV. Of equal importance is that the flock needs to be uniform as measured by CV.
Management at Transfer and Early Lay
As soon as pullets are moved to the laying house, farmers tend to increase feed in order to get pullets into production. This is detrimental if they are not ready to lay. Pullets will start to lay when they are ready and not when the famers want them to lay. A pullet needs to have consumed a “breed specific” total crude protein to be physiologically ready to lay. Overfeeding at this stage will lead to fat deposition around the ovary and reduced production to and beyond peak. Until 5% production, feed strictly according to body weight. They are still “rearing birds” until they reach 5% production.
Trying to increase light to get production when pullets are not physiologically ready is equally detrimental to onset of production. Too early light stimulation at transfer actually retards the onset of production. This is seen mostly in open sided rearing houses during summer. The rearing feed intakes are lower than breed requirements. Stimulating a pullet on a reduced total protein intake retards onset of production.
Feeding into early lay is critical as this sets the platform for a good peak and sustained production post-peak. The demand for nutrients to peak requires both a hen’s body reserves as well as the daily nutrients in the feed. Any limit on nutrients from either source will lead to a poor peak and poor post-peak performance. In other words, a pullet that has poor body reserves will never achieve a good peak lay. She will also most likely show a classic post peak dip. For a hen to rely purely on daily feed intakes to peak generally leads to a nutrient “shortage” and poor peaks. The same applies to well fleshed birds that are “held back” on feed to peak. They too will show poor peak and post-peak dips.
Various breeding companies have methods to decide on feed increments, from the feeding level at the onset of production to the maximum presumed feeding level. At this point I must stress that the maximum feeding level cannot be set in stone. There are numerous factors that will influence what a hen will need to consume in order to achieve a maximum peak. These factors include:
- Pullet weight profile
- Nutrient composition
- Environmental temperatures
- Housing type
- Disease loading
At the risk of being too aggressive on feeding to peak, one can almost feed a hen ad lib to peak. This comment is to get the importance of maximising feed to peak as opposed to the common practice of withholding feed into peak. Underfeeding is more detrimental than over feeding into peak.
Once a hen has received her calculated peak feed by 70% production, this is not the end of the feed allocations but rather needs to be considered as the starting point at which the good manager will now fine tune further feed requirements. Again, there is no rule at which one must stop additional feed, as long as the measured and monitored parameters are in line. The parameters in lay that must be measured, and used in conjuction with one another, when making feed allocations are (in order of importance):
- Egg weight
- Egg production
- Hen weight
The concept of challenge feeding seems to have lost its importance. As a hen approaches peak production there is every likelyhood that the decided level of maximal feeding may NOT fully meet her nutritional needs to peak. Stopping peak feed at this level will be detrimental to her ability to produce to her maximum potential. This is where challenge feeding steps in.
- Give hens an additional 5 grams.
- 3 parameters are now measured: egg weight, production and hen weight.
- If the additional feed is in excess to the bird’s current needs, egg weight will rise followed by the hen weight after 3 days, however, with no increase in peak.
- If the additional feed is needed, the egg and hen weight will remain on the trend line, and production will rise.
- These parameters are measured over 3 days, after which a decision is made to challenge feed a further 5 grams, or remove the challenge feeding.
The important fact that must always be remembered is one cannot set a maximum peak feed if one wants to obtain maximal hen production. How can a calculation take into account all the variable factors that affect a flock at any given stage.
Post Peak Feeding
The emphasis of feeding to peak is rather over feed than under feed. This must, however, take place with strict monitoring of the measurable parameters. These parameters are:
- Egg weight
- Hen weight
- Production levels.
How do we know when peak production has been reached?
- Production no longer responds to challenge feeding
- Egg weights start to rise against the standard trend
- Hen weight will start against the breed standard
It is important to identify this point in the flocks production cycle as feeding will now change from weekly or bi-weekly increases in feed to actual weekly feed withdrawal. To understand feed withdrawal, feed consumed has 3 consequences:
- The need to produce an egg
- To produce an egg of a standard size
- Maintain hen weight against the breed standard or profile
At peak we have now ascertained that egg weights are increasing. This can only be due to feed consumed no longer being able to produce beyond the current production level. This is considered peak production. Feed must now be restricted otherwise the excess feed will lead to obesity and a production drop. As a rule, if one has fed high levels of feed to peak, the feed withdrawal needs to be more aggressive than hens fed low levels to peak. The most detrimental post peak feeding action is to hesitate on feed withdrawal. This leads to over feeding with fat accumulation around the ovary. Fat negatively influences ovum development and hence production.
Feed withdrawal levels can be from 2 – 5 grams in the first week with a weekly withdrawal of 1 – 2 grams. The actual feeding graph post-peak needs to have a concave appearance. While the above is a guideline, please remember to measure the production parameters of egg weight, egg production and hen weight, and use these measures in order to optimise actual feeding levels. Manuals refer to weekly monitoring, but pre-peak, peak and post-peak feeding has such a crucial influence on total production, that I would recommend bi-weekly measuring in order to improve the level of decision making at this critical phase.
Effects of Flock CVs
CVs indicate the variablity in a flock around the mean weight. In other words, a low CV indicates that a high percentage of hens are of a similar weight, while a high CV shows a wide variation in hen weights. As hens come into production, based on protein intake and body weight, it is self explanatory that hens of different weights, or should we say, sexual maturity, their nutrient needs will differ.
When we feed a flock we are actually feeding a mean hen / flock weight. On any given day, the more mature hens will require more feed as she is closer to peak, while the lighter hens will still be settling into their rise to peak. It is self explanatory that these 2 hen groups will have different nutrient needs. Feeding a set feeding level, as we do, will under feed the mature hens and over feed the lighter hens. Unfortunately there is nothing one can do here and both ends of the growth curve will be negatively affected (either over fed or under fed). The only group in the flock that will be correctly fed are those closest to the flock mean. The wider the flock CV, the more detrimental this is to a flock. A well reared flock, with a low CV, will be least affected with the actual feeding level best meeting the majority of the flocks nutritional needs.
Bottom line, all management processes that will positvely influence the CV in rear and then into early lay, play a major role in maximising peak production and overall production sustainability.
It is often the case that male lines are supplied from a number of parent lines. As a result CVs can be wider than one would expect. It is therefore extremely important that management practices are aimed at ensuring optimal feed intake over the entire cockerel flock and thus reducing CVs.
The feeding of cockerels is no different from pullets. Weighing on a weekly basis is vital, as against the actual weights, feed is allocated. Poor weights that don’t reflect the true status of the flock will create erroneous feed allocations and poor uniformity. As for pullets, there is a weight curve and a suggested feed requirement. The weight curve must be attained (or as close as possible), while feed allocations are a theoretical figure. Poor CVs lead to dominance of and reduced mating in lay.
The feeding profiles for cocks shows an increasing feed allocation. This is important. Never take feed off, but rather hold if weights are rising.
As cocks mature, it is common that they will steal feed from the hens. The cock excluders on most feeding systems allow for immature / young cocks to still access hen feeders. This is normal! The important time to watch cock feeding levels and weights is when the access to the hen feed stops. They suddenly have less feed and weights can drop off. This is a critical phase as this is normally when cocks are expected to be most active at peak lay.
As for hens, feed allocations are based on accurate weekly weights. It is extremely important to calculate feed based on a true representative male flock weight.
If we under feed cocks, they become lethargic and stop mating. One would expect weights to fall off when under fed, but this is not the case. Due to inactivity they actually put on weight. The classic fat and lazy syndrome applies to all species! To correct this weight gain, actually feed more. This will have the effect of supplying an increased energy level to the cocks and this in turn will increase their activity. The result is a drop off in weight and increased fertility.