Editor's note: This article is an excerpt from the Cobb Breeder Management Guide and additional articles will follow. The Guide was designed to highlight critical factors that are most likely to influence flock performance. The management recommendations discussed were developed specifically for Cobb products. The recommendations are intended as a reference and supplement to your own flock management skills so that you can apply your knowledge and judgement to obtain consistently good results with the Cobb family of products. To read or download the complete Guide or to view Cobb's other management guides, click here.

Fleshing of males in production is not common but has some unique advantages that can help to establish the correct bodyweight profile in production. The Cobb male fleshing spreadsheet is a tool used to record fleshing values from 1 to 5 (example below). 

The user inputs fleshing scores for the sample population and the spreadsheet calculates percentages and the corresponding weighted average for each group. The weighted average flesh score will be graphically displayed along with the bodyweight. Contact your Cobb Technical Representative for an electronic copy of this spreadsheet.

Male feeding - separate sex feeding

One challenge for the farm manager and the feeding system selected is to distribute a small amount of feed per male as uniformly as possible and keep all males with a uniform growth and activity level. For males, use 20 cm (7 7/8 in) of feeder space with a track system, 8 to 10 males per round feeder and 10 to 12 males with an oval pan feeder. The height of the feeder system is important for all the males to eat comfortably. Normally apply a height that is close to the upper crop height of the males. A measuring stick that is fixed to the male feeder line can help to drop, each day, the feeder line to the correct height so that all males can access the pan feeders without female interference. 

There are many other tools to keep the height of the male feeders correct. A limit switch may be attached to the feeder line so that it is activated when the feeder line reaches the predetermined height when lowered. Keep the male feeder at a height that makes the males stretch slightly to eat and prevents the females from reaching. 

A male feeder should always be stable and not be allowed to swing. The height needs to be frequently adjusted by observing feeding behavior at least once a week up to 30 weeks of age. Chain or mechanical trough feeders are becoming more popular than pan feeders for males. They have some additional advantages including better feed distribution and visibility.

Separate sex feeding (SSF)

It is highly recommended to use Separate Sex Feeding (SSF) in production. Training the males is key to the success of Separate Sex Feeding (SSF). The males need to quickly identify and use their specific feeders. The best option is to have the same type of male feeder in rearing and production. Alternatively, decoy feeders can be used in rearing. For example, if the males are fed on a chain but will use pans in production, place a few pans in the rearing house and manually add some feed. The males will learn to identify the pans as a feed source. Transfer the males a few days earlier (2 to 5 days) so they are specifically trained to eat from their new feeders before the females arrive to the production house.

After both sexes are in the production house, start the female feeder first and when all females position themselves, lower the male feeder system or start male feed distribution. With feed distribution in the dark, delivering feed can be simultaneous but give females access to their feeders about 1 minute ahead of males. 

Separate sex feeding (SSF) allows the use of special male rations. Male diets are widely used in the industry. Furthermore, research and field results confirm that male diets improve fertility. Male rations with lower protein levels (13 %), a 2700 kcal (11.25 MJ/kg) energy level and 0.50 % available lysine, control male bodyweight and breast muscle growth. With specific male rations, it is even more important that the SSF system prevents females from eating out of the male feeder.

True SSF implies that males should not have access to the female feed and vice versa. SSF includes a male exclusion system placed on the female feeder (grill, roller bar, see illustration) and a separate line of pans, trough or tube feeders for the males. The exclusion grill should create both a vertical (60 mm or 2 3/8 in) and horizontal (46 mm or 1 13/16 in) restriction. In systems with a roller bar or wooden board – plank adjust the vertical restriction. Often, planks have three different height settings: 42 mm (1 11/16 in), 46 mm (1 13/16 in) and 50 mm (2 in). Begin at 21 weeks with 42 mm (1 11/16 in), then increase to 46 mm (1 13/16 in) in peak production and finally to 50 mm (2 in) at about 50 weeks of age.

Male weight trends during production

The Cobb standard for male bodyweight is designed to keep the male light early in production - not more than 4 kg (8.8 lb) at 30 weeks and have a consistent growth maximum of 25 g (0.06 lb) per week from 30 weeks to depletion (approximately 4.7 kg (10.3 lb) at 60 weeks). Consistent, positive growth during the first 4 weeks after photo stimulation, is important for testes development (see table below).

Common reasons for poor male fertility related to weight:

• Excessive growth through 30 weeks (4.4 kg; 9.7 lb) and poor growth after 30 weeks due to insufficient feed amounts. In these flocks a number of the males will lose condition.
• Excessive growth through 30 weeks, and bodyweight continuing to increase reaching 5.0 kg (11.0 lb) or higher at 50 weeks of age.

Normal growth through 30 weeks of age but insufficient growth thereafter results in many males losing condition, comb and wattle color. Over fleshed males (> 4 fleshing score) may have reduced mating efficiency due to incomplete mating. As males get too heavy their breast shape flattens, and they become unbalanced when attempting to mate. 

Problems will occur if males are able to eat from female feeders after transfer. Males will gain excess weight and will need more energy for bodyweight maintenance. Females will not have enough feed and limit their development. Consider keeping male feed allocations constant until the combs develop to the point that they cannot eat from female feeders. Add the male feed increase to the female feeders until males cannot eat from female feeders.

Males should never lose weight in production. A loss in bodyweight of >100 g may cause a reduction in sperm quality based on the males’ condition. Monitor weights weekly and adjust feed accordingly. 

Normally feed amounts are not decreased in males. However, if after 30 weeks, the male bodyweight increases too fast, reduce the feed by 5 g/male (1.1 lb/100 males/week) and monitor for 3 to 4 weeks until weight gain stabilizes This is one of the most important periods to decrease feed amounts for males as an emergency procedure.

To read or download the complete Cobb Breeder Management Guide or to view Cobb's other management guides, click here.