Effects of feeding low fishmeal diets with increasing soybean meal levels on growth, gut histology and plasma biochemistry of sea bass.

The aquaculture industry depends upon the development of sustainable protein sources to replace fishmeal (FM) in aquafeeds and the products derived from soybeans are some of the most studied plant feedstuffs. A key area of investigation for continuing to improve modern aquafeeds includes the evaluation of varying proportions and combinations of plant ingredients to identify mixtures that are more efficiently utilized by the fish. This study investigated the effects of increasing soybean meal (SBM) by replacing a mix of plant ingredients in low FM (20%) diets on growth, blood biochemistry profile and gut histology on European sea bass. Five isonitrogenous and isolipidic experimental diets were formulated: four diets containing increasing SBM levels (0, 10, 20 and 30%; 0SBM, 10SBM, 20SBM and 30SBM, respectively) with a low content of FM (20%) and one control diet (0% SBM; 35% FM). Diets containing SBM brought to comparable performance and protein utilization, while 0SBM had negative impact on feed conversion rate and protein utilization. Blood parameters suggested an optimal nutritional status under all feeding treatments, even though slightly decreased values were reported at increasing dietary SBM. Histology examination did not show any changes indicative of soy-induced enteritis. We can conclude that for European sea bass: (i) different blends of plant protein did not affect feed intake despite the 20% FM dietary level; (ii) the inclusion of SBM maintains optimal growth and feed utilization in low FM diets; (iii) blood biochemistry profile showed a good nutritional status under all feeding regimes; (iv) no evidence of soy-induced enteritis was reported in any group fed low FM diets. For formulation of practical diets in on-growing of European sea bass, SBM up to 30% can be successfully incorporated into feeds containing low FM inclusion.

Fatty acid composition of eggs and its relationships to egg and larval viability from domesticated common sole (Solea solea) breeders.

The study of lipids and fatty acids (FAs) has been used in the assessment of egg quality because their composition can influence the fertilization rate, hatching, survival and growth of marine fish larvae. For these reasons, the lipid content (TL) and fatty acid composition of common sole (Solea solea) eggs were measured and correlated to egg and larval viability parameters throughout an entire reproductive season. Seventeen batches of fertile eggs obtained from natural spawning of captive breeders were characterized for the TL, FA profile, hatching rate (HR) and survival rate of larvae (SR) at 0-6 days post-hatching (dph). The egg FA composition reflected the composition of the feed supplied to the broodstock during summer and autumn (before and during vitellogenesis) rather than that supplied during the spawning season. In general, the egg FA profile showed minimal differences among the early-, mid- and late-spawning periods (possibly due to the change of the diet and/or water temperature) indicating that it is possible to obtain a similar egg quality in terms of egg FA profile over 2 months of spawning. Saturated FAs and monounsaturated FAs (MUFA) were positively correlated with HR, while TL, 22 : 6n-3 (DHA), 20 : 4n-6 (ARA), polyunsaturated FAs of the (n-3) series (n-3 PUFA) and polyunsaturated FAs of the (n-6) series were negatively correlated (p ≤ 0.05). MUFA, 20 : 5n-3 (EPA), n-6/n-3 were positively correlated with SR, while DHA, n-3 PUFA, DHA/EPA were negatively correlated (p ≤ 0.05). In conclusion, the feed supplied before and during vitellogenesis has a major role in determining the egg FA profile in common sole. The relationships found between TL and FAs with egg and larval viability parameters differ from many other farmed marine fish species, which may suggest the need for a specific broodstock feed for this species.

Intestinal metabolism of weaned piglets fed a typical United States or European diet with or without supplementation of tributyrin and lactitol.

The aim of the study was to investigate the effects of supplementation of a microencapsulated blend of tributyrin and lactitol (TL) to a standard European (EU) diet without antibiotic growth promoters on intestinal metabolism and mucosa development of weaned piglets and to compare it with a standard US diet containing animal proteins, zinc oxide, copper sulfate, and carbadox. Ninety piglets weaned at 21 d were divided into 3 dietary groups consisting of 5 replicates each: 1) US diet supplemented with 55 mg/kg of carbadox, and 2.5% each of plasma proteins and spray-dried blood cells in the first phase, 3,055 mg/kg of Zn in the first and second phases, and 180 mg/kg of Cu in the third phase; 2) EU diet based on vegetable proteins and no antibiotics; and 3) the same EU diet supplemented with 3,000 mg/kg of microencapsulated TL. The study was divided into 3 phases: 0 to 7, 8 to 21, and 22 to 35 d. On d 7, 21, and 35, animals were weighed, and feed consumption and efficiency were determined. On d 14 and 35, one pig per pen was killed, and the intestinal contents and mucosa from the proximal, middle, distal jejunum and the ileum were sampled. Intestinal wall sections were fixed for histological analysis, and intestinal content was used for VFA, ammonia, and polyamine analysis. Throughout the study (d 0 to 35), the US diet had greater ADG and ADFI than the EU diet (P < 0.05). The EU diet supplemented with TL tended to have 11% greater ADG (P = 0.17). Feeding the EU diet caused a reduction in proximal and middle jejunum villi length by 10% (P < 0.05) and an increase in crypt size in proximal jejunum (P < 0.05) compared with the US diet, probably due to an increased rate of cell loss and crypt cell production. The TL supplementation resulted in longer villi along the jejunum and less deep crypts in the proximal jejunum (+15.9 and -8.9%, respectively; P < 0.05) than the unsupplemented EU diet. The TL diet increased the concentrations of cadaverine and putrescine in the small intestine (P < 0.05) and seemed to increase cadaverine, histamine, putrescine, and spermine in the large intestine by 1.5- to 10-fold compared with the US or EU diet. In conclusion, although the US diet had a greater effect on growth performance and mucosal trophic status than the EU diets, the supplementation with slowly released TL seemed to be an effective tool to partially overcome the adverse effects of vegetable protein diets.

Lipid composition, retention and oxidation in fresh and completely trimmed beef muscles as affected by common culinary practices.

The objective of this study was to determine how and to what extent several culinary practices (i.e. household cooking methods), each applied to the beef muscle deemed most suitable (boiling to infraspinatus, broiling to longissimus lumborum, oven-roasting and microwaving to semitendinosus), could induce significant changes in: lipid and cholesterol contents, fatty acid composition and contents, their true and apparent retention values, and some indices of lipid oxidation. Most nutrients increased their concentration as a consequence of moisture loss through cooking, whilst no substantial variation was induced in fatty acid composition. Nevertheless, each cooking method had its own distinctive heat processing parameters, which interacted with the characteristics peculiar to the pertaining muscle, leading to markedly different evaporative and drip losses, significantly different true retention values for cholesterol and the sum of polyunsaturated fatty acids, distinct responses as to lipid oxidation liability. The selected culinary practices seemed to be able to interact with the composition of the selected muscles, up to the point that pro-oxidant conditions were in some way counteracted by antioxidant effects.

Dietary organic chromium supplementation and its effect on the immune response of rainbow trout (Oncorhynchus mykiss).

Recently, there has been an increasing interest in the potential effect of dietary chromium on the health of fish, particularly with respect to their metabolism and growth. Information as to the role of this mineral on their immune response, is limited however, so the aim of this study was to assess the effects of dietary chromium yeast supplementation on the immune response of rainbow trout (Oncorhynchus mykiss). Juvenile rainbow trout (56 g average weight) were fed three semipurified diets containing different levels of chromium (1540, 2340 and 4110 ppb), obtained by supplementing a basal diet with 800 or 2570 ppb chromium yeast, for 6 weeks. After this, time differences in their immune response were examined. A positive influence was observed on serum lysozyme activity at this time in fish maintained on the high chromium diet. The respiratory burst of head-kidney macrophages was also examined, and statistical differences were found in the level of respiratory burst elicited by macrophages from both groups of fish fed supplemented chromium after 3 and 6 weeks of feeding (absorbance at 3 weeks: 0.118, 0.166. 0.151 and 6 weeks 0.114, 0.168, 0.151 for the 1540, 2340 and 4110 ppb groups). Macrophages of fish receiving diets supplemented with chromium also had a greater ability to phagocytose yeast after 6 weeks than the control fish (40.5, 48 and 48.5% macrophages phagocytic in the 1540, 2340 and 4110 ppb groups, respectively). The results of the study show that chromium yeast is able to modulate the immune response of rainbow trout, and this effect appears to be both dose- and time-dependent.