Dongqing Bai

Verification of protein sparing by feeding carbohydrate to common carp Cyprinus carpio

A 9-week feeding trial in floating freshwater cages (1.0 m×1.0 m×2.0 m) was conducted to study the effects of different dietary levels of protein and starch on growth, body composition, and gene expression of enzymes in common carp, Cyprinus carpio (mean body weight, 36.12±1.18 g) to evaluate the protein-sparing effect of dietary carbohydrate. Four diets were formulated with corn starch as the carbohydrate source to obtain corn starch levels of 6.5%, 13%, 19.5%, or 26% and protein levels of 30.5%, 28.2%, 26.4%, and 24.2%. The results showed no differences in growth performance of fish fed the diets with different protein and corn starch levels, but body composition and glucose metabolic enzyme activity of carp were significantly affected by the different diets (P< 0.05). Weight gain, specific growth rate, and the feed conversion ratio were not different in fish fed the different dietary treatments. Protein efficiency ratio increased significantly as corn starch level increased (P< 0.05). Whole-body crude lipid composition increased with increasing dietary corn starch level (P< 0.05). Glucokinase (GK), hexokinase, and pyruvate kinase (PK) activities increased significantly with increasing dietary corn starch level (P< 0.05), whereas glucose-6-phosphate (G6Pase) activity decreased with increasing dietary corn starch level (P< 0.05). GK gene expression was significantly higher in fish fed the high-corn starch diet than those fed the low-corn starch diet (P< 0.05). G6pase gene expression tended to decrease with increasing starch level (P> 0.05). In summary, the results indicate a protein-sparing effect by substituting carbohydrate in the diet of common carp.

Analysis on the Innovation of Teaching Methods and Its Implementation in Colleges and Universities

Colleges and universities are not only the important base for the cultivation of innovative talents, but also the important parts of the national innovation system, besides, they play an irreplaceable important role in building an innovative country. Based on the experience of study and practice from the author, this paper analyzed the necessity of the innovation of teaching methods to raise creative talents, then discussed how to establish the innovation system of the open and diverse teaching methods, finally put forward the path to promote the innovation of teaching methods.

Protein Sparing Effect of Carbohydrate on Growth Performance, Digestion Ability of Common Carp (Cyprinus carpio) at Different Feeding Frequencies

A 8-week 3 × 2 two-factorial experiment was conducted to investigate effects of dietary carbohydrate levels (5%, 10%, and 20%) and feeding frequencies (fourth daily and twice daily) on the growth, digestion and liver function of common carp (Cyprinus carpio) [initial average weight of (55.37 ± 3.55) g] cultured in floating net cages. Three replicates with 180 common carp were randomly allotted to one treatment with combination of dietary carbohydrate level and feeding frequency in a complete randomized design. The results showed that the weight gain ratio (WGR), special growth ratio (SGR), and protein efficient ratio (PER) were significantly affected by feeding frequency (P < 0.05). Significant effect of feeding frequency on hepatosomatic (HSI) and condition factor (CF) was observed (P < 0.05). Fish fed fourth daily at 5 and 10% dietary carbohydrate levels had significantly higher HSI compared with fish fed twice daily at 5 and 10% dietary carbohydrate levels(P < 0.05). CF was significantly affected by dietary carbohydrate levels (P < 0.05). At 10% dietary carbohydrate level, significant effect on CF of fish fed twice daily was found (P < 0.05), comparing with fish fed fourth daily. Feeding frequency had significant effect on amylase activity of foregut and lipase activity of midgut, and dietary carbohydrate levels significantly affected amylase and lipase activity of midgut (P < 0.05). Lipase activity of fish fed fourth daily at 5% dietary carbohydrate level significantly increased compared to fish fed twice daily at the same carbohydrate level. Comprehensively, the common carp should be fed at 4 meal/d, and the dietary carbohydrate level could be appropriately increased to 5–10%.