Aging hens physiologically need to be mated more often to sustain the same level of fertility as a flock of 35 weeks. Meanwhile roosters become less interested and able to complete mating. So, to get the same fertility level, the older the flock the more attention should be paid to rooster management. Implementing a spiking programme might prove helpful.
By Wiebe van der Sluis, Rooster 45, Doetinchem, the Netherlands
When broiler breeders reach 40 weeks, their fertility levels naturally decline because rooster mating frequency is lower and physiologically the hen needs to be mated more often to maintain fertility. At this point of age flock supervisors should control body weight gain (a small consistent amount is allowed) and prevent an accumulation of excess breast fleshing, because they may have a negative effect on fertility. An excellent method to counter a natural decline in fertility is introducing a spiking programme.
Dr Jeanna L Wilson, extension poultry scientist at the Poultry Science Department of the University of Georgia, Athens (GA), USA, wrote a number of papers on different types of spiking. Her general advice is as the flock ages to increase the number of roosters (7.5-8.5 males/100 females) and spike the aging flock with young, mature roosters. The best time to spike is when the flock is 40-45 weeks of age by adding 2% extra males. Meanwhile obvious culls and large non-productive males should be removed. Removing the large well feathered males ruling the feeder and interrupting productive mating activity, increases fertility from this alone. The spike males must be 25-28 weeks old and should weigh 20-25% more than the average body weight of the hen flock.
Using stud farms
Dr Wilson explained that perhaps the most flexible but most expensive method of spiking, is to grow extra males with a breeder flock. When the flock is moved to the laying house at 20-21 weeks of age, move the extra males to a stud farm and hold them there until the males are 26-28 weeks of age. After males sexually mature and weigh 20-25% more than the average 40 week old hen, they can be used as spike males.
There are many obvious advantages of stud farms. Generally, the environment of the pen caters to the needs of that particular group of roosters to get them in condition to successfully mate once placed in the hen house. The greatest disadvantage is the additional cost of running a separate facility. The stud farm must have separate pens and feeding systems to meet the needs of each age group of males housed in the facility. Males should be provided 3-4 sq ft (about 0.3-0.4 m2) per bird, and 12-14 hours of light per day at 1-3 foot candles (10-30 lux/m2) of light intensity. Dr Wilson suggests to equip the house with the same feeder and drinker the males will see in the hen house to reduce adjustments when they are moved. Her advice is to provide enough feeder space (6-9 males per pen) to make the feed easily available to each male. Evaporative cooling is needed to prevent heat stress prior to moving the males to the hen house. The goal of this interim period is to allow for good weight gain and sexual maturity so that the roosters can compete with older males when moved to the hen house. The secondary goal is to limit mortality and injury of the roosters on the stud farm.
Extra males in the breeder house
If a stud farm is not an option, Dr Wilson suggests to move extra males to the breeder farm with their original flock and hold them until they are 25-27 weeks of age. These males can be intermingled with the flock or placed into a small pen in the breeder house. The advantage of sending the extra males to the hen house is the reduction in facility cost when no stud farm is needed. There are some disadvantages to housing stud males with a hen flock, so believes Dr Wilson. If the roosters are placed with the laying flock, the ratio of males to females may be as high as 10-12 males per 100 hens. This high density may cause the maturing hens to stay on the slats or cause excessive male and female mortality. It is also disruptive to the hen flock when the extra males are removed at 26-29 weeks of age and early fertility may be slow to increase. If the extra males are penned in one area within the hen house, this alleviates the slatting and hen mortality problem, but decreases use of the feeding, watering, and nesting equipment for the rest of the flock. The pens are not built as permanent structures, and the males occasionally get out and hens get into the pen. Typically, there is little control of rooster feed intake when the hen trough is used to feed them. These pens tend to be on the far end of the hen house and often do not get much attention. Rooster mortality in the small holding pen tends to be high and management of the males less than optimum.
A new method of improving fertility is interspiking. This has been successful for some integrated operations where young males are not available or biosecurity concerns will not allow the addition of roosters from another source. Interspiking is moving roosters from one house on a farm to another house on the same farm. This requires some labour to catch and release, but little else. Fertility will increase very quickly (as there is no acclimation period for these roosters), but fertility will decline in about 4-8 weeks as you are still dealing with an older male. Therefore some producers will interspike several times during the life of the flock.
On-farm available roosters can also be used when rooster to hen ratio is low. In that case roosters can be removed from a flock that is being sold and used as spike males. These males could be from those spiked into the flock as young males or they could be older males that are in good shape. The advantage of using roosters that were going for sale as spike roosters is the reduction in chick costs, rearing expenses, and facility expenses. However, these roosters are normally used only when no other roosters are available. The disadvantage of this type spiking is the lower probability of improving fertility because of the age and variable condition of the males.
The greatest problem with any spiking programme, is the biosecurity risk. Blood test results must be obtained from each group of males prior to moving them to a stud farm and before moving them to a flock for spiking. Common vaccination and dubbing programmes are essential as well.
Key elements of spiking
Before spiking, Dr Wilson recommends to survey the roosters and remove the obvious cull roosters and any large inactive males. The large dominant males tend to interfere with mating activity of other males, especially the young, inexperienced spike males. She stresses that there are a number of key elements that should be kept in mind when introducing a spiking programme:
Impact on old males
The addition of 2-3 males per 100 females will initially cause a 'reactivation' of the existing males and increase flock fertility and hatchability. The addition of young males is directly responsible for this increased mating interest of the old males. This effect on fertility only happens if the existing males are in good physical shape. If they are overweight, have foot or leg problems, or in poor condition, do not expect to see this immediate improvement in fertility. The existing males may not be physically capable of increasing their mating frequency. Even if the old rooster is in good condition, this increased mating frequency may be short lived (4-6 weeks).
Adaptation of spike male
It is important that only sexually mature males be used for spiking. Otherwise, the young male cannot compete with the older male for feed and water, and never adapt to the laying facility. High mortality usually results with very little long term improvement in fertility. To increase the chances that the young male will adapt and be accepted into the flock, provide extra feed (1-2 kg/100 roosters) for 2-3 days after spiking, and make sure the male feeder is low enough enabling the spike male to eat from it. The old males can be territorial about feed, and roosters that miss 1-2 days of feed are easy prey for dominant males.
Impact of the spike male
Young males are inexperienced and take 4-6 weeks to effectively mate. If the older males were reactivated, their mating activity will decline at about the same time as the young rooster becomes effective at mating. The result is about 5 to 10 weeks of increased or sustained fertility. However, remember the percentage of old males to young males will be 2:1, and even though the young males are responsible for increasing or sustaining fertility the old males are important. The spike males do not replace the old males; they are purely supplemental.
Expect that rooster mortality will double after spiking (1%, with an increase to 2-3%). Male mortality may take as much as 8-10 weeks to subside. Hen mortality will increase. The increase will not be as dramatic (increase to 0.3 to 1.0%) and should last only 1-2 weeks.
Success not guaranteed
In her concluding remarks Dr Wilson mentioned that the effectiveness of the spike depends on the condition of both old and young males, adaptation of young male, access to feed and water. Initially, spiking will reactivate the old male to increase mating activity when they are physically able. This increases short term fertility.
Generally, spiking results in a 1-3% increase fertility over a 5-10 week period. With some spiked flocks, fertility is maintained (better than 90%) through 60 weeks of age. However, with some flocks the improvement in fertility is not noticeable or never develops. If the spike male does not adjust to the hen house, you may not see any long term increase in fertility. If the old males are in such poor physical condition that you get no increase in mating frequency from them, fertility will slowly increase or just be maintained as the young males start to complete matings.
[Source: World Poultry magazine Vol 30 nr 7, 2014]