Managing breeder males for uniformity raises hatchability
Weight and body condition uniformity are increasingly important with breeder males today.
Uniform male populations give the best fertility since they are easier to manage and because uniformity of bodyweight determines uniformity in testes growth, influences peak and persistency of fertility.
Weight uniformity is probably one of the best indicators of poor environmental or management conditions. Uniformity has a natural tendency to deteriorate from 6 to 14 weeks of age, coinciding with the maintenance and feed management period.
After 14 weeks, uniformity improves as feed amounts increase significantly again. Under poor environmental conditions, uniformity deteriorates rapidly, and even if several grading procedures are performed, the effects are very short-lived.
Here we have two groups of birds. One, under good environmental conditions, maintains a natural and acceptable uniformity trend. The other, under a poor environment, loses uniformity immediately after grading and needs to be re-graded over and over again.
By poor environment, we can consider, inadequate temperatures, poor ventilation, disease challenges, inadequate equipment and lack of proper management. So what are the most common management or equipment deficiencies that affect uniformity?
Excessive stocking density in rearing
First is excess stocking density. Males benefit from lower stocking densities than females, ideally 4-5/sq m. Stocking density conditions bird behaviour, feeding space and the quality of the environment.
Males are naturally aggressive both feeding and interacting with each other. High stocking densities exacerbate this behaviour and ultimately affect the quality and uniformity of the males through competition for feed, feathering and respiratory problems due to ventilation stresses.
Slow distribution of feed
During the maintenance period (6 to 15 weeks) and the early part of the production period (25 to 35 weeks), feed restriction is significant and the males will consume their allocation extremely quickly. These are two periods where uniformity can be totally lost unless every male gets the same feed allowance.
Ideally feed should be delivered instantly (charged pan feeders or winched-up tube feeders lowered full of feed). With chain feeding systems, a two to three-minute distribution time is acceptable.
Lack of grading procedures
Grading means dividing the males into two or three groups (pens) according to their size, which is often linked to their degree of competitiveness when feeding. This way, smaller males have a better chance to compete for feed.
Grading programmes can be very simple (one time only at 4 to 6 weeks) or very complex. However there are some basic rules that should be followed.
Inadequate growing profiles in rearing
A good start in rearing is crucial for weight uniformity, good organ and skeleton development. Standard weights should be achieved at eight weeks, when the males will have developed 75% of their skeletal size.
Excess weight at six weeks of age is, however, not good. Very heavy males will develop big skeletal frames and require more bodyweight and feed during production to maintain proper fleshing and uniformity.
After 16 weeks of age, start stimulating the males with feed to reach standard bodyweights by the time they are light stimulated. Small males will struggle to compete and will not develop testes properly during the first four weeks after light stimulation.
Inadequate adaptation
Inadequate adaptation while transferring from rearing to production farms is a common cause for loss of uniformity, especially with a high incidence of unconditioned birds that need to be culled two or three weeks after transfer. The males need to quickly identify their specific feeders. The best option is to have the same type of male feeder in rearing and production.
Other options include using decoy feeders in the rearing house, transferring the males a few days earlier than the females (2-3 days), starting the male feeders first and keeping the females from eating from the male feeder. This latter approach can be achieved by keeping the male feeder at a height that makes the males stretch slightly to eat and prevents the females from reaching (45cm for adult males).
Poorly designed feeder systems in production
The challenge for the feeding system is to distribute a small amount of feed per male as uniformly as possible. To this end, the male feeding systems should have the correct design.
Today, most male feeding systems are pan feeders, which can be evaluated using several criteria. First, acuracy and distribution speed can be assessed by checking feeders deliver the same amount of feed in every pan instantly.
For comfort, each pan needs to allow eight males to eat comfortably and birds should be in easy reach of the feed. Deep pans are better than flat ones for reach.
Other certeria include is the pan bird friendly? The pan should be supported by few arms and finished with materials that do not injure the birds. Finally, is it stable with a support system which prevents it from swinging.
Lack or excess feeding space
A lack of feeding space will cause poor uniformity since only the more dominant males will have adequate access to feed. In standard pan or tube feeding systems, the adequate number of males is eight per feeder. In chain feeding systems, every bird should have at least 15cm of feeder space.
When there are more feeding pans than required, strong dominant males will have an higher chance to eat their feed allocation quickly and run to other pans not surrounded by males where they will get extra feed. This will create overweight males and destroy uniformity.
Lack of culling
Cull poorly conditioned males regularly. Otherwise the feed allocation of these males will be eaten by other stronger males that will, in turn, get overweight.
Grading tips
- The first grading is the most important it should be done ideally at four weeks. Since the males will still grow their skeleton significantly from four to eight weeks, an early grading will give an opportunity to the small males to develop proper skeletons.
- Grading too many times during rear can disturb hierarchies too much and create unnecessary stress, which negatively affects uniformity and makes grading a non-lasting exercise.
- Use the opportunity that the birds are handled for other reasons to perform a grading.
- Generally, the smallest birds do not require additional feed. Just by having lower competition levels they will grow better.
- At transfer time: (a) select only healthy males with no apparent faults.
(c) match heavier groups of males with heavier females and light males with light females. This helps with hen receptivity and mating efficiency.