Fish by-products are rich in
collagen. Hydrolyzed
collagen derived from fish by-products was used to replace fish meal to evaluate the effects on muscle quality and
glycolipid metabolism of juvenile
triploid crucian carp. A total of 240 juvenile fish with
body weight of 10.01 ± 0.02 g were divided into four groups and fed four diets for 66 days: fish meal (FM) replaced with hydrolyzed
collagen (HC) in 0% (Control), 2% (2% HC), 4% (4% HC), and 6% (6% HC), respectively. The results were as follows: The increased proportion of fish meal replaced with hydrolyzed
collagen linearly and quadratically decreased the specific growth rate (SGR) of
triploid crucian carp (p < 0.05). Compared with the control group, the SGR and intestinal α-
amylase,
trypsin and
lipase activities in the 4% and 6% HC groups significantly decreased (p < 0.05), while there was no significant difference between the control and 2% HC groups (p > 0.05). Total umami
amino acids content, chewiness and myofiber density of muscle in the 4% and 6% HC groups, as well as the
essential fatty acids content in all HC groups increased significantly (p < 0.05). All HC groups significantly increased the serum
glutathione peroxidase (GSH-Px) activity and decreased the serum
malondialdehyde (MDA) content (p < 0.05). When the replacement amount reached 4%, the serum
glucose and
liver glycogen content, the liver and serum
triglyceride (TG) content, and serum total
cholesterol (T-CHO) content were significantly reduced (p < 0.05). In addition, the expression levels of
insulin-like growth factor-1 (IGF-1) of the liver in all HC groups and lipolysis-related genes (
lipoprotein lipase (LPL),
carnitine O-palmitoyltransferase 1 (
CPT 1) and hydroxyacyl-
coenzyme A dehydrogenase (HADH)) of the liver in the 6% of HC group increased significantly (p < 0.05), and the expression levels of lipogenesis-related genes (
fatty acid synthase (FAS) and
sterol regulatory element-binding protein 1 (SREBP 1)) of the liver in the 4% HC and 6% HC groups decreased significantly (p < 0.05). In conclusion, the replacement of 2% fish meal with hydrolyzed
collagen had no negative effects on the growth of
triploid crucian carp, while the replacement of 4% fish meal with hydrolyzed
collagen decreased SGR, but improved the muscle quality and decreased
glycolipid levels. The maximum proportion of hydrolyzed
collagen replacing fish meal should not exceed 4%.