(H2


O2


) levels, decreased mitochondrial glutathione


concentration and reduced activities of antioxidant enzymes, glutathione peroxidase and manganese superoxide dismutase in the hepatic mitochondria of AFB1


-exposed


broilers indicated that the mitochondrial redox balance was disrupted and oxidative stress occurred. Similarly, increased mitochondrial swelling, reduced ATP concentration, and decreased activities of ETC mitochondrial complexes I, II, III, and V were observed in the present study. In addition, the decreased hepatic mRNA expression levels of antioxidant genes were observed in AFB1


-exposed broiler primary


hepatocytes. Overall, the aflatoxin induced mitochondrial oxidative injury by affecting mitochondrial ROS homeostasis and damaging the antioxidant defence system. As observed in a similar broiler study, AFB1


reduced feed


intake, body weight gain, and caused poor feed conversion rate compared with the control diet – the adverse effects of AFB1


on growth performance being related to a decrease in


the protein and energy utilisation as a consequence of a deterioration of the digestive and metabolic efficiency of the birds. Researchers from the Sichuan Agricultural University in China studied the pathogenesis of AFB1


-induced


immunosuppression in broilers and their results showed that AFB1


induced excessive apoptosis of splenic lymphocytes,


which was correlated with increased oxidative stress, evidenced by reduced glutathione peroxidase, glutathione reductase, and catalase activities, and increased malondialdehyde contents.


Protective effects of lycopene To determine the protective effects of lycopene on mitochon- drial oxidative injury and dysfunction in the liver of aflatoxin B1


-exposed broilers, the researchers looked at different com-


ponents of the oxidative system and gene expression of mito- chondrial biogenesis, as follows:


• Mitochondrial redox status: Lycopene showed higher mitochondrial glutathione concentrations and glutathione peroxidase and manganese superoxide dismutase activities, and lower H2


O2 concentrations than the broilers in the AFB1


group. Lycopene also decreased hepatic ROS concentration in AFB1


-exposed broilers.


• Activities of mitochondrial ETC complexes: The lycopene treatment increased activities of mitochondrial electron transfer complexes and reduced mitochondrial swelling. Ly- copene group had higher hepatic ATP concentrations than the AFB1


group. • Gene expression: Compared to the AFB1 group, broilers in


the lycopene group showed upregulated mRNA expression levels of hepatic genes (e.g., PGC-1α, NRF1, and TFAM) relating to mitochondrial antioxidant capacity and biogenesis – alleviating mitochondrial dysfunction by improving mitochondrial biogenesis.


26 ▶ FEED SAFETY | APRIL 2022


Figure 1 – Effects of dietary lycopene (LYC) on performance and hepatic reactive oxygen species (ROS) concentration of aflatoxin B1


(AFB1


60 55 50 45 40


Control


100 90 80 70 60 50


Control )-exposed broilers. *# * AFB1 AFB1+LYC


0.60 0.55 0.50 0.45 40


Control * AFB1 AFB1 +LYC


160 140 120 100 80 60


Control # *


AFB1


AFB1


+LYC


* #


AFB1


AFB1


+LYC


Lycopene improves growth The effects of dietary lycopene supplementation on the growth performance of AFB1


-exposed broilers were observed


(Figure 1) through decreases in feed intake, daily weight gain and feed utilisation (gain: feed ratio). The researchers related the benefits of lycopene on growth performance to its improvement on the oxidative status of broilers observed through decreased ROS and hydrogen peroxide (H2


O2 ) levels, increased mitochondrial glutathione


concentration and increased activities of antioxidant enzymes, glutathione peroxidase and manganese superoxide dismutase in the hepatic mitochondria of AFB1


-exposed


broilers (Figure 1). In a similar broiler study conducted by researchers from the University of Veterinary Medicine Vienna, it was suggested that both the level and length of AFB1


exposure affect the


amount of reduction in weight gain of broilers and that different types of rations used in different studies make it impractical to generalise the dose-response relationship regarding weight gain. The researchers concluded that dietary lycopene protects broilers from aflatoxin B1


-induced liver mitochondrial oxida-


tive injury and dysfunction, which is related to its ability to scavenge free radicals, stimulate mitochondrial antioxidant capacity, and maintain mitochondrial biogenesis. “The results of the present study expand our understanding that lycopene or lycopene-enriched materials could be used as promising dietary modulators for aflatoxin B1


-induced injury in poultry,”


they remarked. References are available on request.


This article is based on the research paper “Protective effects of lycopene on mitochondrial oxidative injury and dysfunction in the liver of aflatoxin B1


-exposed broilers”. The full paper can be accessed in Poultry Science vol 100, issue 11 November 2021.


ADFI (g/d)


ADG (g/d)


ROS (5 of Control group)


G:F (g:g)


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