Ross 308: The Objective Table, and the 21 °C Line Underneath It
not publishedMature weight, rooster
A broiler is not kept to maturity. Aviagen publishes weight for age to day 56 and no mature weight, because no commercial bird reaches one.
not publishedMature weight, hen
A broiler is not kept to maturity. Aviagen publishes weight for age to day 56 and no mature weight, because no commercial bird reaches one.
42 dTo market
Breeder standard, to 3,086 g as-hatched, on-farm. Aviagen, August 2026.
Not namedFree-range standard
Not on the permitted list in PNS/BAFS 262:2018, so stock of this line cannot be sold as free-range under the standard.
The short answer
Ross 308 is one of the two strains behind most sisiw sold as broiler DOCs here. Its published objective is 2,296 g at day 35 on a cumulative FCR of 1.399. Read the booklet’s own conditions before you plan a batch on that, kasi may nakasulat doon na hindi mo mababasa sa kahit anong dealer flyer: growth improves when the house sits below 21 °C from day 21.
Source Aviagen, Ross 308 Broiler Performance Objectives 2022 (read on August 22, 2026)
The objective table, straight off the page
These are Aviagen’s as-hatched figures, which is the row a keeper wants because a bakuran batch is not sexed.
| Day | Body weight | Cumulative intake | Cumulative FCR |
|---|---|---|---|
| 0 | 44 g | — | — |
| 7 | 213 g | 166 g | 0.780 |
| 14 | 533 g | 535 g | 1.005 |
| 21 | 1,012 g | 1,155 g | 1.142 |
| 28 | 1,616 g | 2,051 g | 1.269 |
| 35 | 2,296 g | 3,211 g | 1.399 |
| 42 | 2,998 g | 4,586 g | 1.531 |
Two footnotes in that booklet do real work and almost never travel with the numbers. Body weight is on-farm weight, feed present in the gut. And the FCR includes the chick’s weight at placement and does not account for mortality, kaya ang tunay na feed cost kada manok na naibenta ay mas mataas kaysa dito, dahil may kinain ang mga namatay.
What the booklet says about conditions
Aviagen is not quiet about this, and quoting the table without it is the actual dishonesty rather than the table itself.
These objectives indicate the performance achievable under good management and environmental conditions and when feeding recommended nutrient levels.
The same page lists what stops it: raw material availability limiting nutrient content and intake, extreme climatic conditions reducing performance, and economics limiting the production system. Its own conclusion is that average performance may be lower than the figures presented here.
Then the management points carry the line that matters most in this country: “Keeping ambient temperatures less than 21 °C (69.8 °F) from 21 days onwards may improve growth rates.” Wala pong bakuran sa Pilipinas na 21 °C sa hapon. That is not a criticism of the strain. It is a statement about which half of the table a Philippine keeper is standing in.
| Weight and FCR by day | Published by the breederAviagen 2022 objectives, as-hatched. A target under good management, not a measurement of any flock you can see. |
|---|---|
| Philippine performance | Not published by anybodyNo Philippine institution publishes strain-level broiler weight or FCR. There is no national figure to set beside the objective table. |
| Days to market weight | Left empty here on purposeIt depends on the weight your buyer wants, and no Philippine source publishes a strain-level harvest age. See the harvest-age article for the 28, 35 and 42 day comparison. |
| Mature weight | Not a meaningful figureA broiler is sold long before maturity. A mature-weight column for a meat strain describes a bird nobody keeps. |
Where the Philippine numbers stop
This is the honest boundary of the page. There is a published objective table for Ross 308 and there is a Philippine farmgate price series, at wala pong tulay sa pagitan ng dalawa.
PSA classifies chickens as broiler, layer, native or improved and gamefowl, and stops there. No strain appears in any Philippine statistical table, no Philippine agency publishes a broiler growth curve, and the missing Philippine backyard FCR is recorded on this site’s own gaps register. What a keeper can look up is what a broiler sells for at the farm gate, which is the other end of the same batch.
So use the table as what it is: the ceiling the genetics allow under conditions you do not have. Ang tanong na sagot lang ng sarili mong talaan is how far under it your own birds land, and in which week the gap opens.
Two practical readings
The first is about the shape of the curve rather than its height. Daily gain on the objectives peaks around 100 g a day from day 35 to day 42, at doon din pinakamahal ang pagkain: intake runs above 200 g a day in that window. A batch held longer eats disproportionately for the weight it adds, whatever strain it is.
The second is about which number to write down. Weigh ten birds at day 21 rather than at harvest. The objective is 1,012 g there, cumulative FCR 1.142, and a batch that is going to miss badly at day 35 is usually already visible at day 21 kung titingnan mo.
Questions people actually ask
How heavy is a Ross 308 at 35 days?
2,296 g as-hatched on Aviagen’s 2022 performance objectives, with cumulative feed intake of 3,211 g and a cumulative FCR of 1.399. Aviagen states plainly that these are achievable under good management and environmental conditions, and that average performance may be lower.
What FCR should a Ross 308 hit? Show the answer
1.269 at day 28, 1.399 at day 35 and 1.531 at day 42 on the objective table. The FCR includes the chick’s weight at placement and does not account for mortality, which is stated in the booklet’s own footnotes and is usually dropped when the number is quoted.
Do Philippine broilers reach the Ross 308 objectives? Show the answer
Nobody publishes an answer. No Philippine institution publishes strain-level broiler performance, so there is no national figure to set against the table. What Aviagen does publish is that keeping ambient temperature below 21 °C from day 21 onwards may improve growth rates.
What is the difference between Ross 308 and Ross 308 FF? Show the answer
Feathering. The 308 is a slow-feathering bird that produces sexable broilers; the 308 FF produces all fast-feathering broilers. The performance objectives booklet covers both, and the as-hatched table quoted here is shared.