Search

Copyright of Acta Agriculturae Zhejiangensis is the property of Acta Agriculturae Zhejiangensis Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study was conducted to evaluate the effect of dietary protein levels on growth performance, muscle composition, digestive enzymes activities, hemolymph biochemical indices and ovary development of pre-adult red swamp crayfish Procambarus clarkii (initial weight = 12.86 ± 0.10 g). Six isoenergetic diets (fish meal, soybean meal, gluten, and shrimp powder as main protein sources) were formulated to contain graded levels of 20.70 %, 24.70 %, 30.56 %, 35.77 %, 41.12 % and 44.64 % crude protein. Each diet was assigned to triplicate groups of 15 experimental crayfish (10 female and 5 male) for 8 weeks. Our results showed that weight gain (WG) increased with dietary protein supplementation from 20.7% to 35.77%, and then decreased with further increases in dietary protein. Broken-line regression analysis based on WG showed that the optimal dietary protein level for maximum growth performance of crayfish was 39.60 %. Feed conversion ratio (FCR) exhibited an opposite trend as observed in WG, with the lowest in crayfish fed the 30.56 % or 35.77 % protein diet. Protein efficiency ratio (PER) in crayfish fed the 41.12 % or 44.64 % protein diet was significantly lower than that in crayfish fed the 20.70–30.56 % protein diet. Hepatosomatic index (HSI) value of crayfish decreased with dietary protein supplementation and achieved minimum values at 35.77 % or 41.12 % protein diet. The highest crude protein content of tail muscle was found in crayfish fed the diet containing 35.77 % or 41.12 % protein. Activities of protease and lipase in both hepatopancreas and intestine were significantly affected by dietary protein levels, while amylase activity showed no significant difference. Dietary protein also significantly induced the contents of hemolymph total protein, albumin, globulin, glucose, total cholesterol and low-density lipoprotein, along with aspartate transaminase and alanine transaminase activities. Moreover, histological analysis revealed that the ovary development of most female crayfish fed the 35.77–41.12 % protein diet were at stage V, which had a higher frequency of mature oocytes than that of females fed other protein diets. Thus, these results provide the theoretical basis for feed formulation to determine the appropriate protein requirement of pre-adult red swamp crayfish.

A 10‐week feeding trial was conducted to investigate the effects of dietary raw starch (RS)/gelatinized starch (GS) ratios on the growth, digestive functions, intestinal histology and the growth hormone‐insulin‐like growth factor‐I (GH‐IGF‐I) axis of Megalobrama amblycephala. Fish were randomly fed five diets containing various RS/GS ratios: 100/0, 75/25, 50/50, 25/75 and 0/100. Fish in the 75/25 group obtained the highest weight gain rate, specific growth rate, protein efficiency ratio and nitrogen retention efficiency compared with other groups, whereas the opposite was true for feed conversion ratio. Intestinal activities of amylase, maltase and sucrase all achieved the highest values in the 75/25 group. The highest lipase and α‐glucosidase activities were found in the 25/75 and 50/50 groups respectively. Activities of protease, alkaline phosphatase and Na+,K+‐ATP decreased with the decreasing of RS/GS ratios. The villi length and crypt depth of the 75/25 group were significantly higher than that of the 100/0 group. Furthermore, the transcriptions of GH increased with the decreasing of RS/GS ratios with the highest observed in the 75/25 group. Overall, our findings indicated that a RS/GS ratio of 75/25 could benefit the growth performance of Megalobrama amblycephala by increasing intestinal digestive and absorptive capabilities as well as promoting GH release. [ABSTRACT FROM AUTHOR]

In the present study, biochemical compositions changes and the related digestive enzymes activities were analyzed during development of eggs and yolk-sac larvae of turbot Scophthalmus maximus . Results showed that activities of pepsin and chymotrypsin increased on the whole, although small decreases occurred at gastrula stage. Trypsin activity presented the minimal value of 25.72 U/mg protein at blastula stage followed by obvious increase thereafter. Amylase activity was not detected until gastrula stage and increased later. As for lipase, it kept fluctuant tendency. The changes of digestive enzymes activities revealed the biochemical compositions dynamics. Both essential amino acids (EAA) and non-essential amino acids (NEAA) increased to the peak at blastula stage and decreased thereafter. Furthermore, the main components were leucine, lysine, valine, arginine and phenylalanine in EAA, and glutamic acid, aspartic acid, alanine and proline in NEAA. Free essential amino acids (FEAA) and non-essential amino acids (FNEAA) contents presented similar patterns of “decrease-increase-decrease-increase-decrease” as development went on, showing the maximal value of 271.00, 133.00 μg/g weight respectively at hatching day. Meanwhile, the main components were leucine, valine, threonine and lysine within FEAA, and alanine, tyrosine and serine within FNEAA. Regarding fatty acids contents, the quantitatively predominant fatty acids were C16:0 in saturates fatty acids (SFA), C18:1n-9 in monounsaturates fatty acids (MUFA), and C18:2n-6, C20:4n-6 (ARA) as well as C22:6n-3 (DHA) in polyunsaturates fatty acids (PUFA). Considering the utilization, there existed the preferential consumption of the unsaturated fatty acids (UFA) from cleavage to blastula stages, from segmentation stage to hatching and from 1 days after hatching (DAH) to 2 DAH, and SFA in other periods. Within the UFA, PUFA were consumed at a higher rate than MUFA from cleavage stage to blastula stage as well as yolk-sac periods, while MUFA were used at a more rapid rate during the other days. As for the individual fatty acids, there was a preferential consumption of C16:0, C16:1n-7 and C20:5n-3 during ontogeny. Overall, the changeable biochemical compositions revealed that the predominant energy fuel is carbohydrates before cleavage stage, amino acids until gastrula stage and fatty acids until 2 DAH. The above results are very valuable for clarifying nutritional requirements of turbot embryos and larvae, and deeply understanding the developmental mechanism. [ABSTRACT FROM AUTHOR]

Abstract: In this study, diets containing 5, 10, 15, and 20% Gracilaria lemaneiformis (GL) (D1–D4 diet) were prepared to investigate the effects of GL on growth performance, carcass composition, activities of digestive enzymes, transaminases activities of black sea bream (Acanthopagrus schlegelii) juvenile. Weight Gain (WG) and Feed Efficiency Ratio (FER) of the fish fed D4 diet were significantly lower than that of control group. Fish fed with the D4 diet showed significantly lower crude lipid of both body and liver and Hepato-Somatic Index (HSI) than those fed with the control diet. Activities of pepsin in the stomach, lipase and amylase in the anterior intestine were significantly suppressed in fish which were fed with the D4 diet (P <0.05). On the other hand, the activities of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were significantly higher in fish which were fed with the D4 diet (P <0.05) than that of the control group. These results indicate that incorporation of the GL in the diet at up to 15% level for juvenile black sea bream is feasible in terms of the growth performance and the physiological state. [Copyright &y& Elsevier]

In a 80-day feeding trial, a total of 1050 juvenile Jian carp ( Cyprinus carpio var. Jian) with an average initial weight of 10.71 ± 0.05 g were fed semi-purified diets containing seven graded levels of pyridoxine (0.20, 1.71, 3.23, 4.96, 6.32, 8.58 and 12.39 mg pyridoxine kg−1 diet). Results indicated that with increasing dietary pyridoxine levels up to 4.96 mg kg−1 diet, percent weight gain (PWG) and specific growth rate (SGR) were improved, and no differences were found with further increase of pyridoxine levels. Feed intake also followed the similar pattern to that observed with PWG and SGR when dietary pyridoxine levels were ≤6.32 mg kg−1 diet. But feed efficiency and protein efficiency ratio were not affected by pyridoxine levels. Crude protein of carcass, productive protein value and plasma ammonia concentration were improved with increasing dietary pyridoxine levels up to 4.96 mg kg−1 diet. Amylase activities in the intestine were improved with increasing dietary pyridoxine levels up to 4.96 mg kg−1 diet, but protease and lipase activities in the intestine were not affected by pyridoxine levels. Na+, K+-ATPase and Gamma-glutamyl transpeptidase activities in proximal intestine, mid intestine (MI) and distal intestine (DI) were lowest when fed the diet containing 1.71 mg pyridoxine kg−1 diet. The alkaline phosphatase activities in MI and DI followed the same pattern. The dietary pyridoxine requirement of juvenile Jian carp based on PWG estimated by broken line model was 6.07 mg pyridoxine kg−1 diet. [ABSTRACT FROM AUTHOR]