Short answer: the Ross 308 target for broiler weight at 40 days is 2,798 g, reached on about 4,175 g of feed per bird and an FCR of 1.49. A farm in Punjab will usually sit a little below that, and the real decision at day 40 is not the weight but whether another two days of feed still pay.
Vital Feeds (Private) Limited, an animal feed manufacturer in Arifwala, Punjab, wrote this guide for broiler growers who sell between day 35 and day 42. It carries no feed prices. You bring your own rates and the table does the rest.
What is the Ross 308 broiler weight and feed used from day 35 to day 42?
The figures below are the as-hatched (mixed male and female) objectives in Aviagen's Ross 308 Performance Objectives 2022. The last column is not in the Aviagen table. We worked it out from the rows, to show what each day costs you in feed.
| Day | Live weight (g) | Feed used so far (g) | FCR | Feed for each extra kg gained since day 35 |
|---|---|---|---|---|
| 35 | 2,296 | 3,211 | 1.399 | starting point |
| 36 | 2,396 | 3,396 | 1.418 | 1.85 kg |
| 37 | 2,496 | 3,584 | 1.437 | 1.87 kg |
| 38 | 2,597 | 3,777 | 1.456 | 1.88 kg |
| 39 | 2,697 | 3,974 | 1.474 | 1.90 kg |
| 40 | 2,798 | 4,175 | 1.493 | 1.92 kg |
| 41 | 2,898 | 4,379 | 1.512 | 1.94 kg |
| 42 | 2,998 | 4,586 | 1.531 | 1.96 kg |
Aviagen notes that weight is on-farm body weight with feed still in the gut, and that the objectives are met only under good management. Our own working ranges for a good Pakistani farm are on the broiler weight chart by age: 2,000 to 2,200 g at day 35 and 2,650 to 2,900 g at day 42. A flock at day 40 that sits between those two ranges is on a normal curve.
How much feed does a broiler eat by day 40?
About 4,175 g per living bird. At day 40 the Ross 308 bird eats about 201 g a day and gains about 100 g a day, so on that single day it turns roughly 2 kg of feed into 1 kg of weight. Compare that with the crop average of 1.49 and you see why FCR rises every day after the third week.
For a shed of 1,000 birds, 4,175 g each is about 4,175 kg, or 84 bags of 50 kg. Add 5 to 10 percent for spillage and wastage, as in our broiler feed consumption per bird chart, and order against the number of birds alive, not the number placed. The broiler feed calculator does the same sum for any flock size and selling age.
When is the best day to sell, day 38, 40 or 42?
The table gives a price-free rule. Between day 40 and day 42 the Ross 308 bird adds 200 g and eats 411 g more feed, which is 2.06 kg of feed for every extra kilogram of weight. So the live rate per kilogram must be at least 2.1 times your feed rate per kilogram just to pay for the extra feed. Water, labour, heating or cooling and the risk of losing birds are not in that number.
- Work it out with your own rates: extra weight in kg multiplied by the live rate, minus extra feed in kg multiplied by the feed rate. If the result is small or negative, sell.
- Weak flock: a flock that is behind the curve eats the same but gains less, so its extra days are dearer than the table. Sell earlier.
- Hot weather: heat cuts intake and raises deaths late in the crop. Do not hold birds into a heat wave for two more days of gain.
- Buyer demand: if the trader pays more for a heavier bird, run the sum with that rate, not the one you hope for.
Why is my flock lighter than the table at day 40?
Check the causes in this order: water flow at the far drinkers, shed temperature and ventilation, feeder space, and feed quality such as fines at the bottom of the pans. Our seven FCR checks take you through them. If birds are dull or deaths are rising, call your vet the same day, because feed cannot cure disease.
What should you record before you decide?
- Weigh a sample: at least 100 birds from three places in the shed, at the same time of day.
- Record feed used: bags opened minus bags left, divided by birds alive.
- Work out FCR: total feed used divided by total weight of birds.
- Compare with day 40 above: 2,798 g, 4,175 g of feed and an FCR of 1.49 are the breeder goal, not a promise. Your best earlier crop is the fairer benchmark.
- Run the sell sum: use today's live rate and feed rate, then decide.
Using a finisher that holds its pellet shape in the pans helps keep waste down in these last weeks. See our broiler starter, grower and finisher feed.
Written by the Vital Feeds editorial team.
How this guide was made: weights, feed used per living bird and FCR for days 35 to 42 are read from Aviagen's Ross 308 Performance Objectives 2022 (as-hatched table); the extra-feed column, the 2.06 ratio and the bag count are our own arithmetic from those rows; working ranges are from our broiler weight chart; checked against the source table on 10 November 2026.
Want help planning feed for your next flock? Message the mill on WhatsApp (UAN 0311 1555136), or find your nearest Vital Feeds dealer.