Cobb Breeder Administration Information: Strategies for grading breeders

8 August 2024

8 minute learn

Editor’s be aware: This text is an excerpt from the Cobb Breeder Administration Information and extra articles will comply with. The Information was designed to focus on important elements which can be probably to affect flock efficiency. The administration suggestions mentioned had been developed particularly for Cobb merchandise. The suggestions are supposed as a reference and complement to your individual flock administration abilities so to apply your data and judgement to acquire constantly good outcomes with the Cobb household of merchandise. To learn or obtain the whole Information or to view Cobb’s different administration guides, click on right here.

It is rather vital to have the flock on the right weight and uniformity by 4 weeks with a most of 5 % above or under the usual. Appropriate weights and excessive uniformity at 4 weeks of age will stop extreme feed restrictions or growing feed quantities in the course of the upkeep interval. 

An vital instrument to enhance uniformity is grading. Grading is the method of sorting particular person birds into classes primarily based on body weight (tremendous mild, mild, common, heavy) in order that birds inside respective classes could be managed again to straightforward. Sorting birds into classes could be achieved after taking particular person weights and calculating uniformity, CV and normal deviations.

Carry out a 100 % weighing and grading when the flock is 7 to 14 days previous. This enables the birds to be grouped by weights and feed consumption, which controls competitors for feed from a really early age. The following 100 % flock gradings ought to happen at 4, 8 and 12 weeks of age or when uniformity is under 65 %. Birds ought to be categorised in heavy, medium and light-weight in comparison with the typical weight. Don’t delay grading ages or the benefit obtained within the first grading will be diminished. 

It could be useful to judge the outcomes of grading carried out at an earlier age, for instance, at 3, 7 and 11 weeks of age. It’s clear that if gradings are carried out early, it’s potential to acquire and preserve uniformity equal to or better than 80 %. In some areas, the price of labor prohibits a number of gradings. In these markets, if only one grading could be achieved, the perfect age is between 21 and 28 days of age. Performing a grading at this age will present extra time to right any uniformity points.

Whatever the variety of gradings achieved in rearing, it is extremely vital to have the fundamental administration standards right together with: sufficient feeder house, quick feed distribution (at nighttime), good chook distribution over the entire home, fixed feed will increase on a weekly foundation and sufficient consuming water obtainable with the right water strain. Males comply with the identical grading idea as females and, generally, ought to be 5 % larger in uniformity than the females. Males symbolize solely 10 % of the flock however are accountable for 50 % of the offspring.

The typical minimal uniformity in rearing ought to be above 70 % (± 10 % variation of the imply) from 3 to twenty weeks. This uniformity ought to be maintained pretty fixed or ought to improve in the direction of the top of the rearing interval. Uniformity under 70 % signifies there are feed consumption points and the flock will not be uniform. Being current at feeding is without doubt one of the most vital occasions of the day. It’s then that errors could be recognized, and fast changes could be made in order that the flock continues to develop uniformly.

Automated grading machines

There are a number of fashions in the marketplace. A bigger mannequin is out there and is appropriate for firms with flocks of greater than 300,000. This machine can vaccinate pullets however will not be straightforward to maneuver. In distinction, different smaller fashions are readily cell and constructed of stainless-steel for straightforward cleansing. These smaller fashions are restricted to grading chicks and birds as much as 20 weeks of age. Typically, grading with machines is beneficial for two gradings at 3 to 4 and 10 to 12 weeks of age, to preserve common uniformity in rearing nicely above 75%. 

Benefits of computerized grading embrace:

• Could be sooner than hand grading and sometimes requires much less personnel
• Capability primarily based on fashions can grade from 1500 to 3000 birds per hour
• Kinds birds with precise weight ranges and no errors with counting birds which can be sorted into teams (a most important situation of hand grading)

If extra info is required, contact your Cobb consultant to get info on the newest developments.

Weighing and grading by hand

Digital hanging scales can be found for grading by hand. Many digital scales can document and retailer weights to the closest gram, calculate a median weight, and show histograms of the load distributions. 

The cutoff values for sorting the flock into teams could be programed to make weighing and sorting sooner and simpler. Lastly, digital scales can even rely the variety of birds that had been weighed and the ultimate variety of birds in every group could be displayed on the size. You will need to be aware that, if the variety of birds in every group will not be correct, then the feed allocations can’t be precisely calculated.

Grading process

Cobb recommends sorting birds into 3 teams: heavy, common, and light-weight. Relying on uniformity and CV, a 4th group (tremendous mild) can be utilized.

Some homes have fastened pens or partitions, and in these homes, at the least one pen ought to be left empty at placement for the sorting course of. You will need to do not forget that if birds are moved to an empty pen throughout sorting to switch a number of the litter from the used pen to the unused pen to facilitate the biking of the coccidia vaccine. If fastened pen or partitions are getting used, the scale of the pen ought to be used to calculate the utmost variety of birds per pen primarily based on flooring, feeder and drinker house. Likewise, for adjustable pens and partitions, regulate the scale of those areas primarily based on flooring, feeder, and drinker house required for every chook. If flooring, drinker and feeder house will not be adjusted to satisfy chook necessities throughout the pens, sorting birds can truly trigger extra issues! 

Stocking density is vital for welfare and uniformity causes. If pen density ranges are too excessive, uniformity can diminish. In some settings the place labor is available, a number of small pens could be ready. On this case, it is strongly recommended that the variety of birds per pen not exceed 1,000 birds with 600 to 800 birds per pen being splendid. In homes with 8,000 to 10,000 birds, small pens usually are not sensible. Every pen ought to have an impartial feeding system. If this isn’t potential, supplementary feeders can be used to regulate the feed allocations to every pen.

Grading and sorting course of

1. Previous to grading, a portion the flock (3 to five %) ought to be weighed. (It’s endorsed to gather a pattern weight even when computerized scales are getting used). Decide the typical, normal deviation and CV or uniformity (additional reference). There are two methods to find out the sorting weights:
   1. Use normal deviation as a cutoff. On this manner, 68 % of the flock can be positioned within the common class, and the sunshine group (- 1 SD) will include 16 % of the flock. The remaining 16 % of the flock can be + 1 SD and belong to the heavy group. For instance, if there are 3,000 birds in a flock, 2000 can be common weight, whereas 500 can be mild and 500 can be heavy. This strategy works with all flocks however could be very efficient for flocks with poor uniformity. Usually, beneath good administration situations and with out gradings the uniformity can be round 70 to 72 %. Subsequently, working with +/- 1 SD can be extra pure for flock uniformity.
   2. Utilizing a plus or minus 10 % calculation can be used to grade and type birds into teams in response to the desk (under).
2. After the cutoff worth has been calculated. Every chook ought to be weighed and sorted into the right group (see diagram under). Digital scales can be used to program cutoff values for every group to make sorting sooner and simpler. The scales can even rely the variety of birds being sorted into every group.
3. If hand weighing, re-weigh a pattern of birds from every pen after sorting. Calculate common body weight, the variation (CV), and uniformity. Use this knowledge to find out changes to feed allocations to deliver the body weight again to the goal. It’s also a superb follow to recount the birds per pen to make certain the right variety of birds get the right feed allocation after grading. Flawed chook numbers per pen are thought-about one of many main errors seen with hand weighing.



Flock administration after grading

Calculate feed allocations for every group primarily based on variety of birds and common body weight to deliver body weight again on track (see body weight correction curves in chapter 8).

• Feed allocations ought to by no means be decreased!
• Any will increase in feed quantities ought to be achieved conservatively. Consider, that it is probably not crucial to extend feed quantities as competitors for feed can be decreased after sorting the flock.
• Proceed monitoring bodyweights with weekly weighing.



Competitors for feed is at all times current all through the birds’ lives. As famous, weight grading at an early age enhances administration of feed consumption by separating the flock into particular weight classes and feeding again to straightforward body weight. Inside sorted teams, it is not uncommon to see uniformity above 90 % after grading. Nonetheless, quickly after grading, anticipate uniformity to say no to a typical degree of 70 to 72 % as pecking (social) order and feed competitors turn out to be re-established inside sorted pens. 

If after the primary sorting, uniformity of the inhabitants throughout all pens drops to 65 % or under, a further sorting and grading ought to be carried out. As well as, decide why the uniformity continues to lower. Usually feed administration points are concerned. A crop examine can even assist decide poor uniformity causes. Some producers carry out a number of grading and sortings throughout rearing as a part of an ordinary protocol. For subsequent grading and sortings, comply with the identical protocol as described.

To learn or obtain the whole Cobb Breeder Administration Information or to view Cobb’s different administration guides, click on right here.