Why does feeding rancid/oxidized fats or rice bran cause liver necrosis, rancid yolk flavor, and severe mortality in brown layers?

Fats and oils (such as crude soybean oil or rice bran oil) are highly concentrated energy sources in layer feeds. However, under high ambient temperatures and humidity in Pakistan, these unsaturated fatty acids are highly susceptible to auto-oxidation. This process converts lipids into toxic lipid peroxides, hydroperoxides, aldehydes, and ketones (rancidity). When brown layers ingest rancid fats, these reactive free radicals directly attack the phospholipid bilayers of the intestinal mucosa and hepatocyte (liver) membranes. This oxidative stress causes massive liver cell necrosis, severe inflammation, and blocks liver lipoprotein synthesis, triggering Fatty Liver Hemorrhagic Syndrome (FLHS). Furthermore, these oxidized chemical compounds are deposited directly into the egg yolk, causing a pale yolk color, a distinct fishy or rancid yolk odor, and a drop in Haugh units. Incorporating high-potency synthetic antioxidants (like ethoxyquin, BHT, or BHA) or natural tocopherols in feed is vital to prevent oxidation. Farmers can study lipid chemistry in the Poultry Encyclopedia, buy commercial feed antioxidants on Poultry Plaza, monitor daily raw grain prices on Poultry Rates, and list premium eggs on Murghi Mandi.