Intermittent cold stimulation acclimates broilers to acute cold stress by affecting cardiac lipid metabolism

This study aimed to investigate whether intermittent cold stimulation can induce adaptation in broilers to acute cold stress (ACS) by regulating the lipid metabolism of hearts.

CS0 were kept at normal rearing temperature, while CS3 and CS5 were exposed to 3°C for 3 and 5 hours, respectively, on alternate days lower than CS0 from 15d to 35d. On 50d, broilers in three groups were exposed to ACS at 10°C for 12 hours (Y12). The levels of corticosterone (CORT) and liothyronine (T3), mRNA and protein levels of heart adenosine monophosphate (AMP)-activated protein kinase/mammalian target of rapamycin (AMPK/mTOR) pathway genes were assessed at 36 d, 50 d and Y12.

At 36d, mRNA levels of AMPKα, acyl-CoA oxidase (ACO), mTOR, sterolregulatory element binding protein (SREBP), stearoyl-coA desaturase (SCD), acetyl-coA carboxylase (ACC), fatty acid synthase (FAS) and protein level of peroxisome proliferatorsactivated receptor α (PPARα) in CS3 and CS5 were significantly lower than those in CS0 (p<0.05). At 50d, compared to CS0, mRNA levels of PPARα, carnitine palmitoyltransferase1 (CPT1), ACO, tuberous sclerosis complex (TSC), SREBP and SCD, as well as protein levels of p-AMPKα/AMPKα, PPARα and SREBP were significantly increased in CS5 (p<0.05). At Y12, the levels of T3 in CS3 and CS5 were significantly higher than those in CS0 (p<0.05), mRNA levels of CPT1, ACO, SREBP, SCD and protein levels of p-AMPKα/AMPKα, SREBP, and FAS were significantly higher in CS5 than in CS0 and CS3 (p<0.05). However, compared to 50d, at Y12, mRNA levels of AMPKα, CPT1 and ACO in CS3 and CS5 significantly decreased (p<0.05), while protein levels of p-AMPKα/AMPKα significantly increased (p<0.05).

This study suggested that intermittent cold stimulation at 3°C lower than normal rearing temperature for 5h could help broilers adapt to the ACS by promoting heart lipid metabolism.