- ✓Know the figures that announce a problem before mortality does
- ✓Calculate your own flock’s benchmarks (7-day weight, water, stocking density, feeders)
- ✓Understand why keeping birds too long becomes more and more expensive
The warning table
Every costly mistake leaves a trace in a figure that can be recorded on the farm. This table brings together the benchmarks from the earlier lessons of this track.
| Figure to follow | Benchmark | If the figure slips, check |
|---|---|---|
| 7-day weight | 4 to 5 times the weight on arrival | Floor heat, water, feed, crops |
| Water drunk per day | Must rise every day | Breakdown, warm water, disease, heat |
| Weekly weight | 70 to 85% of the table in a hot open-sided house | Start, feed, heat, health |
| Uniformity or CV | 80% or more, or a CV of 8% | Feeder space, litter, ammonia |
| Expected stocking density at sale | 30 kg per m² maximum with natural ventilation | Number of chicks placed |
| Litter | Hand test: it breaks up | Drinkers, misting, stocking density |
Sources: Cobb and Efficiency Plus.
Mistake 1: a failed start that nobody sees
The 7-day weight is an excellent summary of how well the start went. The Cobb guide is clear: failing to reach the right 7-day weight leads to a poorer-performing flock. Cold litter on arrival means less feed eaten, poorer growth and an uneven flock.
The chicks weighed 40 g on average on arrival (5% of boxes weighed). At 7 days, a good result is therefore 160 to 200 g (4 to 5 times more). The weighing gives 130 g, barely more than 3 times the arrival weight: warning. Floor temperature, feet, water and space at the trays must be checked straight away. Without a weighing on arrival and at 7 days, nobody would have seen it before the end of the flock.
Source: Cobb.
Mistake 2: not monitoring water
Water consumption must increase over time. If it falls at any point, the Cobb guide says to review the birds’ health, the house and management at once. The Efficiency Plus benchmarks allow about 1.70 litres of water per kilo of feed in good conditions, and much more in strong heat (lesson 4 of this track).
A flock of 5,000 birds aged 28 days. Benchmark: about 259 ml per bird per day, i.e. about 1,300 litres for the flock, more in strong heat. The meter shows 1,400 litres on Monday, then 1,150 litres on Tuesday in similar heat: the drop is the first signal, often before the first deaths. Look straight away for a leak, a breakdown, water that is too warm in the tank or sick birds, and call the veterinarian if the cause is not mechanical.
Sources: Cobb and Efficiency Plus.
Mistake 3: keeping birds too long
The flock’s feed conversion ratio rises with age (lesson 1). But the most telling figure is the feed needed for each extra kilo gained: it climbs quickly at the end of the flock.
| Period | Extra feed per bird | Extra weight gained | Feed per 1 kg gained |
|---|---|---|---|
| 28 to 35 days | 1.28 kg | 0.74 kg | about 1.7 kg |
| 35 to 42 days | 1.46 kg | 0.76 kg | about 1.9 kg |
| 42 to 45 days | 0.68 kg | 0.32 kg | about 2.1 kg |
Calculated from the Cobb 500 targets (males and females mixed). Source: Cobb.
In other words, after 42 days, each extra kilo of chicken takes more than 2 kilos of feed, and heavy birds suffer more from the heat. The selling age is decided with these figures and your own prices, in the profitability calculator on the website.
Mistake 4: too many birds per m²
Too high a stocking density leads to leg problems, scratches, bruising and higher mortality, and the litter can no longer cope. Stocking density is calculated at the expected selling weight, not on the number of chicks.
A 500 m² house with natural ventilation, limit 30 kg per m². With 6,000 birds sold at 2.5 kg: 15,000 kg ÷ 500 = 30 kg per m², at the limit. If the same 6,000 birds are kept until 3 kg: 18,000 kg ÷ 500 = 36 kg per m², above the limit. To sell at 3 kg, about 5,000 chicks should have been placed (5,000 × 3 = 15,000 kg), or part of the flock sold earlier (lesson 10 of this track).
Source: Cobb.
Mistake 5: too few feeders, or empty ones
When feeder space is short, growth falls and uniformity deteriorates. A feeding system breakdown also causes panic and scratches, which downgrade the birds at the processing plant.
Cobb benchmark: 60 to 70 birds per 33 cm pan. For 5,000 birds, you therefore need 72 to 84 pans. With only 50 pans, there are 100 birds per pan: growth and uniformity are likely to drop. If uniformity falls, for example, from about 80% (CV of 8%) to 60% (CV of 12%), the flock has become uneven: recount the pans before looking for another cause.
Source: Cobb.
The records that raise the alarm
None of these mistakes can be seen without records. The Cobb guide advises displaying the daily record in each house and noting:
- Deaths and culls.
- Feed and water consumed, and the water-to-feed ratio.
- Water treatments.
- The day’s minimum and maximum temperatures and humidity.
- Management changes (curtains, light, feed).
Source: Cobb.
For the entrepreneur
- ›Ask for the water drunk every day and the weight every week: they are the two cheapest alarms on the farm.
- ›Calculate stocking density at the expected selling weight before ordering the chicks.
- ›After 42 days, each extra kilo takes more than 2 kg of feed: decide the selling age with the calculator.
For the technician
- ›Weigh 5% of the boxes on arrival and the flock at 7 days; report any weight below 4 times the arrival weight.
- ›Read the water meter every day at the same time and report any drop.
- ›Count the pans: 60 to 70 birds per pan, never an empty feeder.
The 3 questions to ask your technician this week
- How much did the chicks weigh on arrival, and how much do they weigh at 7 days?
- Did water intake rise every day this week? If not, on which day did it fall?
- How many birds per pan do we have at the moment?
Key points
- •Big mistakes show up in the figures before mortality: 7-day weight, water, weekly weight, CV.
- •At 7 days: 4 to 5 times the arrival weight; for 40 g chicks, 160 to 200 g.
- •Water intake must rise every day; a drop is a warning.
- •Cobb 500: about 1.9 kg of feed per kilo gained between 35 and 42 days, more than 2 kg after 42 days.
- •Stocking density calculated at selling weight: 30 kg per m² maximum with natural ventilation.
- •60 to 70 birds per 33 cm pan; a feeding breakdown causes scratches.