Dietary simultaneous replacement of fish meal and fish oil with blends of plant proteins and vegetable oils in yellowfin seabream (Acanthopagrus latus) fry: Growth,digestive enzymes,antioxidant status and skin mucosal immunity

A 56‐day nutritional research was performed to examine the influence of alternative vegetal protein and lipid sources on performance of yellowfin seabream fry (Acanthopagrus latus) (0.5 ± 0.0 g). In this regard, five isoproteic (Ca. 500 g/kg) and isolipidic (Ca. 150 g/kg) diets were formulated in which fish meal (FM) and fish oil (FO) were simultaneously replaced with blends of plant proteins (PP, soybean meal and corn gluten) and vegetal oils (VO, canola and soybean oils) at 20% (SR20), 40% (SR40), 60% (SR40) and 80% (SR80) levels, respectively; meanwhile, a control diet (SR0) was formulated based on FM and FO. Growth and feed utilization were not influenced by experimental diets. The fatty acid profile of fillet drastically altered by dietary treatments. Fish fed with the SR60 and SR80 feeds had higher total protease, trypsin and α‐amylase activities than other treatments. The antioxidant enzyme activities and glutathione content in liver were enhanced in fish fed with the SR40, SR60 and SR80 diets. Skin mucosal immune parameters including total protein content, alkaline phosphatase and alternative complement pathway activities in the control group were relatively lower than the vegetal treatments. According to these results, it is recommended that 410 g/kg of FM and 45 g of FO/kg can be replaced with alternative vegetal sources in diet for A. latus fry.     

Dietary lysine requirement of juvenile Protonibea diacanthus

An 8‐week experiment was conducted to determine the optimal dietary lysine requirement for juvenile Protonibea diacanthus. Six isonitrogenous and isolipidic diets were formulated to contain levels of 10.8 (L10.8), 18.2 (L18.2), 26.1 (L26.1), 33.9 (L33.9), 40.7 (L40.7) and 48.6 g/kg (L48.6) of diets and were fed to the juvenile Protonibea diacanthus, respectively. The results indicated that weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER) and final weight (FW) increased as the dietary lysine level increased from 10.8 to 26.1 g/kg and then decreased as the dietary lysine levels further increased (p < .05). The lowest feed conversion ratio (FCR) was found when dietary lysine level was 26.1 g/kg. Analysis of specific growth rate by two slope broken‐line model indicated that the estimated optimal dietary levels of lysine for juvenile Protonibea diacanthus was 23.06 g/kg (51.24 g/kg dietary protein).     

Effects of alternative dietary lipid sources on growth performance,health status and fillet fatty acid composition of hybrid sturgeon (Acipenser baeri Brandt ♀ × Acipenser schrenckii Brandt ♂)

An 8‐week trial was conducted to determine the effects of total replacement of 12.9% fish oil (FO) with soybean oil (SBO), peanut oil (PNO), sunflower seed oil (SFSO), corn oil (CO) and canola oil (CNO) on growth performance, health status and fillet fatty acid composition of hybrid sturgeon (194.28 ± 0.14 g). Compared to the FO group, dietary SBO decreased growth performance (p < .05), increased serum glucose and hepatic lipid content (p < .05). No obvious adverse effects on growth performance and health status were observed in PNO, SFSO and CO groups (p > 0.05). The fish fed with CNO had increased growth performance (p < .05), reduced serum ALT, AST, LDL‐C (p < .05) and enhanced serum GSH‐Px, T‐AOC, and LZM, MPO, C4 (p < .05). The contents of C18:1n9, C18:2n6, and ∑n‐3 PUFA and ∑n‐6 PUFA in fillets showed a positive linear correlation with the diets (p < .05). In summary, PNO, SFSO and CO are probable alternative lipid sources to fully replace FO. Hybrid sturgeon prefers to use CNO as a lipid source with improved growth performance and health status. The fillet fatty acid composition mirrors the dietary fatty acid composition.     

Effects of ferulic acid on growth performance,immunity and antioxidant status in genetically improved farmed tilapia (Oreochromis niloticus) fed oxidized fish oil

A study was conducted to characterize the effects of dietary oxidized fish oil on the growth performance, immunity and antioxidant status of genetically improved farmed tilapia (Oreochromis niloticus) and to determine the role of ferulic acid on the oxidative damage induced by the oxidized fish oil. The tilapia (13.73 ± 0.31 g) were fed four experimental diets containing untreated (peroxide value, POV: 2.2 meq/kg) and highly oxidized (POV: 120.6 meq/kg) fish oil either with or without ferulic acid (0 or 400 mg/kg) supplementation for 12 weeks. From the results, the oxidized fish oil treatments increased antioxidant enzyme activities and MDA values but decreased the weight gain and the immunological parameters in tilapia. Meanwhile, the serum biochemical indices were significantly affected by the oxidized fish oil. Besides, the addition of ferulic acid partially counteracted the free radical‐induced damage and improved the health status of tilapia. In conclusion, the oxidized fish oil may induce oxidative stress, destroy liver, dysregulate lipid metabolism as well as reduce non‐specific immunity, and eventually result in growth inhibition of tilapia. The ferulic acid supplementation partially offset the negative effects of the oxidized fish oil on tilapia.     

Lipid metabolism in juveniles of Yellowtail,Seriola dorsalis,fed different levels of dietary methionine containing a low level of cholesterol: Implication in feed formulation

The involvement of dietary methionine in the lipid metabolism of Seriola dorsalis, at different levels of dietary methionine (Met), and low content of cholesterol was investigated. Four diets containing different Met levels and a low amount of cholesterol (0.23 g/kg diet) were prepared. One hundred and eighty juveniles (16.2 ± 1.5 g) were randomly distributed into each 12 500‐L ponds. After 60 days, the growth in weight (%) significantly increased following the Met supplementation, whereas SGR of all the experimental treatments was higher than the Basal Diet. The expression of the insulin‐like growth factor (IGF‐1) increased significantly (0.2‐fold) and was complemented by significant changes in Mat, BHMT and HMG‐CoA, for fish that were in the low and higher Met levels. The cholesterol content in the whole body and liver increased following methionine supplementation, similarly to that observed for crude lipids, in particular in the whole body and liver tissues. However, the relative amount of most fatty acids remained unchanged. Only the oleic acid increased at a higher amount of Met. Therefore, once the dietary requirement of methionine is met, the methionine is used to synthesize cholesterol. It is recommended to supply a higher amount of methionine to spare energy for growth.     

Nutritional evaluation of two marine microalgae as feedstock for aquafeed

Using microalgae for animal nutrition provides an economically viable route for microalgae‐based technological innovation, especially in combination with CO₂ fixation given current global warming. However, this technology still lacks sufficient evaluation for screening microalgae for specific animals; meanwhile, current studies show some prejudice regarding ‘essential’ or ‘non‐essential’ ingredients. The results show that Dunaliella salina and Nannochloropsis salina were able to accumulate high protein (30%–57%) and lipid (20%–46%) content without affecting the performance of CO₂ fixation, which reached 0.28 and 0.23 g L^?1 day^?1 respectively. Both species exhibited high quality of lipids and proteins for Penaeus monodon based on the profiling. The essential fatty acid indexes (EFAI) for N. salina and D. salina were 3.81 and 9.02 respectively. Butyric acid was found to be present in both D. salina (12.03%) and N. salina (4.87%) based on the total fatty acids (FAs). The essential amino acid indexes (EAAI) for D. salina and N. salina were 2.23 and 1.29 respectively. Arginine was the most abundant essential amino acid (EAA) in both D. salina (10.83%) and N. salina (13.35%) on the basis of total amino acids (AAs). This study comprehensively compares the nutritional quality of the two commercial marine microalgae of D. salina and N. salina with the potential to be used as sustainable sources of lipids and proteins to reduce or even replace the traditional fish oil and fish meal in aquafeeds.     

Differential regulation on C5 expression in goose versus mammals by glucose/palmitate provides a potential protection for goose fatty liver

Goose fatty liver is a specific type of nonalcoholic fatty liver that is protected from harmful effects associated with severe steatosis. Our previous findings suggest that suppression of the complement C5 may be relevant, but the mechanism is unclear. Therefore, in this study, we first verified the expression pattern of complement genes (including C5) during goose fatty liver formation and then determined the liver fat content and fatty acid composition by high-performance liquid chromatography (HPLC), followed by selecting the differential metabolites to treat HepG2, goose and mouse primary hepatocytes, aiming to explore the mechanism of C5 and inflammation suppression in goose fatty liver. The data confirmed the suppression of complement genes (including C5) in goose fatty livers. Moreover, fat content was significantly higher in fatty liver versus normal ones, with oleic acid and palmitic acid dominantly accounting for the difference. In line with this, high concentration of palmitate led to down regulation of C5 expression in goose primary hepatocytes whereas upregulation in mouse primary hepatocytes and HepG2 cells. In conclusion, regulation on C5 expression by fatty liver related factors including high level of palmitic acid may contribute to the protection of goose liver from severe hepatic steatosis.     

氨基酸钙对烤烟生长及烟叶品质的影响

为了进一步优化烤烟营养调控技术、提升烟叶品质,采取大田试验的方式,研究了氨基酸钙对烤烟生长以及内在品质的影响。结果表明,施用氨基酸钙后烤烟田间长势较好,平顶期烟株株高、叶面积等农艺性状指标均优于常规对照,烤后烟叶具有较高的均价和上中等烟比例,能够增加烤后烟叶的经济效益。施用氨基酸钙对烟叶品质具有一定的改善作用,可以提升烤后上部烟叶的两糖含量,并对烟碱含量具有一定的降低作用,在团棵期和旺长期分次施用氨基酸钙B2F和C3F等级烟叶的感官评吸质量最好。综合分析,在本试验条件下,氨基酸钙的施用方式以在团棵期或旺长期分次施用较为适宜。     

Performance,milk fatty acid composition and behaviour of high-yielding Holstein dairy cows given a limited grazing period

The effects of a limited grazing period on the performance, behaviour and milk composition of high-yielding dairy cows were examined. A total of 56 Holstein cows yielding 44.7 ± 0.42 kg/day were allocated to one of four treatments in one of two, 4-week periods. Treatments were as follows: control (C)—cows housed and offered TMR ad libitum; early grazing (EG)—cows grazed for 6 hr after morning milking then housed; delayed grazing (DG)—cows returned to housing for 1 hr after morning milking followed by grazing for 6 hr, then housed; restricted TMR (RT)—cows grazed for 6 hr after morning milking, then housed and fed TMR at 75% of ad libitum. Intake of TMR was highest in cows receiving C, intermediate in EG and DG, and lowest in RT at 26.9, 23.6, 24.7 and 20.3 kg DM/day respectively. Pasture intake was similar in cows receiving EG or DG, but was higher in RT at 2.4, 2.0 and 3.5 kg DM/day respectively. Milk yield was similar between cows receiving C, EG or DG, but lowest in RT at 45.7, 44.2, 44.9 and 41.7 kg/cow, respectively, while milk fat content of C18:3 n-3 was increased by grazing. Cows in C spent more than 55 min/day longer lying and had three additional lying bouts/day, while lying bouts were shorter than for cows receiving EG, RT or DG. It is concluded that high-yielding cows can be grazed for 6 hr/day with little impact on performance, provided TMR is available ad libitum when housed.     

A systematic approach to determine the impact of elevated CO2 levels on the chemical composition of wheat (Triticum aestivum)

Two wheat genetic lines (responsive and non-responsive to elevated CO₂) grown under ambient and free-air CO₂ enrichment (FACE) conditions were compared using fuzzy chromatography mass spectrometry (FCMS) metabolite fingerprinting. A more comprehensive survey of the changes in their chemical composition was made on selected samples using ultra-high-performance liquid chromatography (UHPLC) metabolomic profiling with high resolution accurate mass/tandem mass spectrometry (HRAM/MSⁿ). Principal component analysis (PCA) of the metabolite fingerprints showed four clusters for the two genetic lines (responsive and non-responsive) and the two CO₂ levels (ambient and elevated) in score plots. Metabolite profiling of representative samples for each of the four clusters identified 25 and 16 compounds from negative and positive data, respectively, including amino acids, saccharides, phenolic acids, flavonoids, and lipids. Loading plots demonstrated that some saccharides and lipids were responsible for discriminating between not only two genetic lines but also two CO₂ levels. Analysis of free amino acids (not bound) showed a clear pattern of reduced concentration for both lines with elevated CO₂. After acid hydrolysis, the responsive line 6 (41% increase in yield) showed the same pattern observed for free amino acids, but the non-responsive line 5 (6% increase in yield) showed different trends in concentrations of amino acids with elevated CO₂.