There are many ways to track the progress and development of today’s modern broiler breeders. Breast development or flesh scoring, signs of sexual development, and fat scoring are a few methods. However, one of the easiest and practical ways to track flock progress is evaluating body weight trends by regular weighing. Following the body weight standard as recommended by the breeding company is key to productive and persistent flock performance. Tracking a flock’s body weight will provide data to make decisions for long term and consistent performance.
Weighing Technique
Weighing should be done weekly and accurately with a consistent sampling procedure. On the day of chick arrival, day 7 and day 14, bulk weighing can be done. At this age, a minimum of 2% of the population should be weighed. For bulk weighing, a platform electronic scale can be used with sufficient space to weigh a group of 5 to 10 birds.
Once the flock reaches 3 weeks of age, it is recommended to weigh individual birds and increase the sample size to 3 to 5% of the population. Weigh birds from three different locations (front, middle, back) of each house to make the sample more representative of the flock.
To increase accuracy of the sampling, use a catching pen, do not randomly pick up and weigh birds, and do not force birds into the pen. Forcing birds into the pen may result in more underweight birds in the pen as heavier birds are more reluctant to move. Open the catching pen and allow the birds to walk into the pen. Weigh every bird individually inside the catch pen, including small birds, and do not reject any weights, except for sexing errors. After each bird is weighed, release the bird into the house. Continue weighing until the pen is empty. Record each weight and calculate the average weight as well as the flock weight distribution.
Rearing
It is best to weigh the flocks at the same time of the week and the same hour of the day. The best option is to measure dry weight by weighing the flock on the off-feed day of a skip-a-day feeding program or before feeding if it’s an everyday feeding program. In some cases where weighing before feeding is not possible, weighing can be done 6 hours or more after the feed clean-up. During rearing, knowing the flock’s body weight is very crucial as feed management decisions will be based on weights. This will determine the feed amount needed on the following days/weeks, and whether it should be maintained or increased. Inaccurate weighing may cause the flocks to be off the target weight which would eventually jeopardize the flock performance.
Transfer
Body weight is critical during pullet transfer. Birds should not lose weight. To monitor any weight loss, mark a portion of the flock, usually 1%, depending on the size of the flock, to be weighed before and after the transfer. Weigh the marked birds a few hours before transfer and 4 to 5 days after transfer.
Production
Switch to an everyday feeding program at around 21 weeks of age. This is necessary as the maturing pullets require a consistent nutrient intake to support their reproductive development and maturation. At this time, body weights should be measured in the afternoons or at least 6 hours after feed clean-up. Weights should be measured weekly until 45 weeks of age, after which, weighing can be done every other week especially if the flock has good production persistency.
Males
Large variations in male weights are quite common due to higher activity levels and smaller populations, relative to the females. It is crucial to have a good representative sample from different locations. If spiking is done, mark all spike males and weigh only the primary males (around 3% of the population).
Weighing Times
Feed amount allocations during rearing are based on measured body weight, while during laying they are also based on egg production and egg weight. Correct feed amounts can only be determined if the body weight is measured accurately every week. Palpation of fat pad or abdominal fat from 25 weeks to peak production can be an additional indicator for feed allocation adjustments.
There are some points in rearing where body weights can be considered critical. Achieving the target body weight at day 7 (four times the initial chick weight) is essential for proper growth and early uniformity. The accurate 7-day weight can indicate whether brooding needs to be extended, as well as when the feed restriction should start.
The 4-week body weight can be an indication of the quality of management and nutrition. A good 4-week body weight is the foundation for frame development and flock uniformity.
From week 16 to 20, females need to increase body weight by minimum 36% to gain enough breast conformation (fleshing) and fat reserve in preparation for light stimulation. From onset of lay to peak production, the flock should increase 19 to 20% in body weight. Weight gain after peak production should be slower for better production persistency.
Accurate body weight is considered one of the factors determining the peak feed amount and feed reduction amounts. Every flock is slightly different, plus local conditions and management experience can influence decisions on feed allocation amounts. However, in general, the feed amount should be reduced from the peak amount by 6 to 10% over the period of several weeks.
Weighing Equipment
Accurate weighing data can only be achieved using reliable and calibrated equipment. Scale calibration should be done regularly. Consult the manufacturer for calibration frequency.
- Conventional suspended or hanging scales must have a capacity of 5 kg ± 20 g increments. With conventional mechanical and dial scales, the data input as well as the calculation are manual.
- Electronic suspended scales will record and store weights to the nearest gram, calculate an average weight, display histograms and have the capability to print out results.
- Digital scales are normally used to weigh young chicks individually or in groups. To weigh chicks up to 7 days of age, digital scales need to have a capacity of 1 kg.
Analyzing the data
After each weekly weighing, plot and analyze the data as soon as possible. Plotting the data into weight and uniformity graphs can help track the development of the flock. If the flock body weight and uniformity are not according to the standard, investigate immediately to determine any issues. Possible causes can include disease, over density, lack of feeder space, and feed and water problems. Finally, if the weighing results are inconsistent or not according to the expected results, it is better to repeat the weighing process