Case studies: diagnosing a flock that is behind in growth

The method in four questions

• Is the weighing right? Same day and same time every week, about 100 chickens in 3 places in the house, compared with the table for the right type of chicken.
• Where is the flock? Calculate: measured weight ÷ target weight × 100.
• Since when? A gap present from 14 days often comes from brooding. A gap that appears suddenly signals a recent event: disease, lack of water, heat, change of feed.
• What do the other figures say? Water drunk, feed eaten, deaths, uniformity, behaviour of the birds.

What matters most is that your flock’s curve follows the shape of the target curve. A gap that widens week after week signals a problem.

Case 1: the false alarm

A technician weighs a flock of hybrids aged 42 days: 1.10 kg on average. He compares it with the red broiler table (1.66 kg) and finds 66%: he panics.

Compared with the hybrids table (1.12 kg at 42 days), the flock is at 98% of target: it is excellent. Hybrids grow more slowly; they are never compared with the red broiler.

Case 2: a delay from the start

Flock of red broilers:

On the flock sheet: cold feet reported on arrival, 78% of crops full at 24 hours (instead of 95%), and chickens jostling at the feeders for the past three weeks.

Reading: the gap exists from 14 days and is widening. Brooding failed (floor too cold, chicks that did not all find water and feed), then the lack of space at the feeders made the delay worse.

• Straight away: add feeders and drinkers, check the stocking density (6 to 8 chickens per m²) and that feed never runs out.
• For the sale: this flock will reach its weight later; recalculate the selling age with the weighings of the coming weeks.
• For the next flock: heating 48 hours before, floor at 32 °C, feet at 4 to 6 hours and crops at 24 hours (lesson 7 of this track).

Case 3: a sudden drop

Flock of hybrids:

The flock gained 50 g in a week, instead of about 250 g. On the sheet: water drunk has been falling since 44 days without any change in heat, a few more deaths every day, dull birds.

Reading: the flock was following its curve well, then everything stops. A drop in water consumption is often the first sign of disease.

• First check that water is reaching everywhere: a water failure also makes consumption drop.
• If water is arriving normally, call your area’s veterinarian without waiting. Show them the flock sheet: vaccines given according to their protocol, treatments, deaths, water drunk.
• Do not give any product at random: the veterinarian decides.
• Tighten biosecurity: dead birds collected every day, visits stopped, footbath kept clean.

Case 4: an uneven flock

Flock of barred grey at 42 days: 1,300 g on average against a target of 1,606 g, that is 81%, normal in an open-sided house. But only 58% of the chickens are within ± 10% of the average weight: uniformity is poor (80% and over for a uniform flock).

Reading: some of the chickens are eating and drinking badly. Causes to look for: water, feed, space, heat, health.

• Are there enough feeders and drinkers, and are they well spread out? A chicken should never have to walk more than 3 m to drink.
• Is part of the house hotter (sunny side, area without air)? The chickens eat less there.
• Is the stocking density respected?
• Are sick or lame birds staying away from the feeders?

At the sale, sort the chickens into weight lots (lesson 9 of this track): an uneven flock sells badly per bird.

Case 5: an end of flock that stalls

Flock of red broilers in the hot season:

The flock now gains only 100 g per week. The chickens pant at the hottest times and each eats about 1 kg of feed per week: that makes about 10 kg of feed per kilo gained.

Reading: heat is weighing on heavy chickens at the end of the flock. Each extra week is very expensive in feed.

• Cool the birds: curtains opened low on both sides, circulation fans, cool water at all times, feeders raised about 6 hours before the hottest time.
• Misting from about 28 °C, never when the air is already very humid (over 70%).
• Consider selling now: compare what the weight gained brings in with the week’s feed (lesson 3 of this track).