Replacing Fish Meal with Hydrolyzed Collagen Derived from Fish By-Products Improved Muscle Quality and Glycolipid Metabolism of Triploid Crucian Carp

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%.

Limitations to wheat starch digestion in growing broiler chickens: a brief review

Starch digestibility may be suboptimal in broilers fed pelleted wheat-based diets. In the present review, the digestion and absorption process related to starch is presented, followed by a discussion of the effect of wheat characteristics and bird-related effects. Enzyme secretion or glucose absorption and metabolism have not been shown to be limiting factors. Suboptimal starch digestibility is primarily observed when a large proportion of wheat is included in the diet, and appears to be partly associated with characteristics of the wheat such as hardness and cell wall structure, which cause starch granules to remain entrapped in the protein matrix and the cell wall of the endosperm or aleurone layer. There are indications that low starch digestibility is negatively correlated with feed intake, and that such a feed over-consumption is linked to an under-developed gizzard.

Kinetics of amino acid and glucose absorption following pancreatic diversion in the pig

An experiment was conducted in the pig to determine the consequences of deprivation of exocrine pancreatic secretion on the composition and quantity of nutrients absorbed after intake of a balanced diet. Five growing pigs (53·8 kg body weight) were fitted with permanent catheters in the portal vein and the carotid artery and with an electromagnetic flow probe around the portal vein to measure the exchanges between the blood and the intestinal lumen. They were also fitted with a permanent catheter in the duct of Wirsung to educe the exocrine pancreatic secretion and another one in the duodenum in order to reintroduce it. In each animal, glucose, amino-N and amino acid absorption as well as insulin and glucagon production were measured over a period of 10 h after the meal (semi-purified diet based on purified starch and containing 180 g fish meal/kg, DM content of the meal 731 g), either in the presence of pancreatic juice (group C : immediate reintroduction), or in the absence of pancreatic juice (group D: deprivation). The deprivation of pancreatic juice provoked a marked depression in the absorption of glucose (D 67·9 (SEM 27·9) g/10 h, C 437·7 (SEM 39·5) g/10 h, P < 0·00l), and of amino-N (D 7·55 (SEM 0·54) g/10 h, C 15·80 (SEM 0·79) g/10 h, P < 0·001). The composition of the mixture of amino acids in the portal blood was only slightly modified: only the levels of histidine (P < 0·05) and of valine (P < 0·06, NS) decreased in the absence of pancreatic juice. Insulin production was much lower (by 64%, P < 0·05) in the absence of pancreatic juice whereas that of glucagon was not affected.

The level and origin of amylase (EC 3.2.1.1) in the digestive tract of chicks receiving trypsin inhibitors in their diet

1. Amylase (EC 3.2.1.1) activity found in the intestinal tract of chicks posterior to the stomach is of endogenous origin, as amylase in the food is inactivated by the low pH in the stomachs. 2. Ingestion of raw soya-bean diet (RSD) or of heated soya-bean diet (HSD) supplemented with trypsin inhibitors induced higher amylase activites in the lower part of the small intestine and caecum as compared with HSD. 3. Ingestion of RSD after ligation at the end of the duodenum, end of the ileum or one of the cacea, or injection of soya-bean trypsin inhibitor into a aligated caecum, indicated that there is no amylase synthesis by the intestinal tract cells or microflora as a response to the presence of RSD or trypsin inhibitors. 4. It seems that amylase found in the digestive tract of the chick is of pancreatic origin and the RSD or trypsin inhibitors induce higher pancreatic amylase secretion than HSD which (the additiona amylase) accumulates mainly in the caeca.