Dietary long chain polyunsaturated n-3 fatty acids (
n-3 FA
) may be beneficial to broiler breeder (
BB
) development. Therefore, the effects of feeding sources of docosahexaenoic acid (
DHA
) and α-linolenic acid (
ALA
) from hatch through to 22 weeks of age (
woa
) on growth, organ weight, and jejunal histomorphology were investigated. A total of 588-day-old Ross × Ross 708 BB were reared on one of 3 diets: 1) control, corn-soybean meal diet, 2) Control + 1% microalgae (
DMA
,
Aurantichytrium limacinum
), as a source of DHA and 3) Control + 2.50% co-extruded full fat flaxseed and pulse mixture (
FFF
, 1:1 wt/wt), as a source of ALA. Diets DMA and FFF had similar total n-3 and n-6: n-3 ratio. Diets were allocated to floor pens (28 birds/pen) to give 9 or 6 replicates per diet for control or DMA and FFF, respectively and fed according to breeder curve in 3 phases: starter (0–4 woa), grower (5–19 woa), and pre-breeder (20–22 woa). Individual body weight (
BW
) was taken weekly and 6 birds/pen necropsied at 5 and 12 woa for gastrointestinal, spleen, bursa, and liver weight and samples for jejunal histomorphology. There was no (
P
> 0.05) diet effect on growth by 20 woa. With exception of 5 woa, pullets fed DMA showed (
P
< 0.001) lower BW coefficient of variation (
C.V
.) than pullets fed control between 2 and 7 woa. However, pullets fed DMA had higher BW CV at 20 woa than birds fed either control or FFF. At 5 woa, birds fed DMA had taller (
P
≤ 0.01) villi and deeper crypt than birds fed either control or FFF but VH or CD were similar (
P
> 0.05) between CON and FFF pullets. At 12 woa, birds fed FFF had taller VH than birds fed control diet but similar (
P
> 0.05) to that of birds fed DMA. Therefore, different responses to sources of omega-3 FA may implicate other components, however, the BW uniformity and intestinal histomorphology responses suggested benefits of feeding omega-3 FA during rearing.