Suchergebnisse

Given the forecast of world population growth and the consequent increase in nutritional needs for both humans and animals, animal production will increase dramatically by 2050. For this reason, alternative farming methods are sought to improve sustainability, reduce the environmental impact, in order to guarantee a production consistent with the growth forecasts. Improving welfare is one of the factors that can enhance the sustainability of a farm. Healthy animals with competent immune defences are animals from which originates a final product of better quality and on which less pharmacological aids will be used. To this purpose we decided to test honey bee pollen in two species of marine fish, to verify its antioxidant effect and the its capacity to enhance both the innate and the adaptive immune response. Honey bee pollen is gaining attention as a health-promoter in fish and polyphenols are considered the principal biomarkers of quality for commercially distributed pollen preparations. The aim of the first trial was to evaluate the effects of the inclusion of honey bee pollen (HBP) in meagre (Argyrosoumus regius) juveniles diets on growth performance, diet digestibility, intestinal morphology and immunohistochemistry. Furthermore, stress-related molecular markers and biochemical blood profile of fish were assessed, together with mineral trace and toxic elements concentration in pollen and diets. Trial was conducted at the Institute of Marine Biology, Biotechnology and Aquaculture (IMBBC) of the Hellenic Centre for Marine Research (Crete, Greece). Specimens of meagre (360) of 3.34±0.14 g initial body weight, were randomly allocated in twelve 500 l circular tanks (30 fish per tank). Four diets were formulated: a control diet and three experimental diets with 1%, 2.5% and 4% of HBP inclusion as fed basis. All the growth parameters and crude protein and ether extract digestibility coefficients were negatively linearly affected by increased HBP inclusion (p < 0.0001). Histology of medium intestine showed slight signs of alterations in group HPB1 and HPB2.5 compared to control. Fish from HBP4 group showed severe alterations at the intestinal mucosa level. Immunohistochemical detection of tumour necrosis factor- α (TNF-α) in the medium intestine showed the presence of TNF-α+ cells in the lamina propria, that resulted in accordance with the increased level of the TNF-α protein detected by immunoblotting in the liver. This stress situation was confirmed by the increased hepatic level of Heat Shock Protein 70 (Hsp70) (p < 0.05) in fish fed the HBP4 diet and by the linear decrease of total serum protein levels in HBP containing diets (p < 0.0001). These negative effects can be related to the ultrastructure of the bee pollen grains walls that make the bioactive substances unavailable and can irritate the intestine of a carnivorous fish such as meagre. In view of these results, in the second study, carried out on gilthead sea bream, we wanted to verify whether these negative effects could be overcome by the inclusion in the feed of the bioactive fractions previously extracted from pollen, using advanced techniques such as SFE, which does not involve the use of solvents.This method is considered "green" and it conjugates, to the extraction power, the avoidance of solvents. The immune-stimulatory effect of two levels of honey bee pollen (5% and 10%) and its supercritical fluid extract (0.5% and 1%) included in the diet for Sparus aurata was tested. The preliminary evaluation of the antioxidant properties of the pollen extracts, obtained by chemical and supercritical fluids extractions, attested that the supercritical fluid extract showed the best antioxidants performances. Furthermore, the results demonstrate that the diets supplemented with pollen extract had a stimulatory effect on serum immunity, respect to the inclusion of raw pollen. More specifically, serum peroxidase, protease, antiprotease, lysozyme activities, as well as the bactericidal activity (against Vibrio anguillarium and Vibrio harveyii) were significantly increased in fish fed the diets supplemented with supercritical fluid extract, respect to the fish fed on control and on diets supplemented with 5% and 10% of raw pollen, suggesting to consider this natural resources as supplement in aquaculture. Another aspect that we have considered is the use of innovative protein as feed. Insect meals could be an alternative protein source for livestock, and they would also be able to reduce the environmental problems related to intensive animal production systems. European legislation currently authorizes the use of seven insect species in aquaculture, however, there is still no legislation that regulates the use in the poultry sector. The aim of the third study was to evaluate productive performance, blood analysis, nutrient digestibility, and changes in the internal organs of laying hens fed Hermetia illucens larvae meal (HI) at two different substitution levels (25 or 50%) of soybean meal (SBM). A total of 162 Hy-line Brown hens (sixteen weeks old) were equally divided into three experimental groups and fed isoprotein and isoenergetic diets. Egg weight, feed intake, and feed conversion rate were not affected by the soybean meal substitution at both inclusion levels of insect meal. Egg mass was positively affected by the insect meal diets, as was the lay percentage, although only at the lowest inclusion level. Dry matter, organic matter, and crude protein digestibility coefficients were lower for the diet with 50% of sostitution, probably due to the negative effect of chitin. A reduction in serum cholesterol and triglycerides was observed in both insect-meal fed groups, while serum globulin level increased only at the highest level of insect meal inclusion, and, consequently, the albumin to globulin ratio decreased. Overall, a protein replacement of 25% with an insect meal from Hermetia illucens larvae in the diet of laying hens seems to be more suitable and closer to the optimal level. The fourth and last trial was subsequent of the third one. In this case was evaluated the effects of feeding a Hermetia illucens larvae meal on the different intestinal traits of hens, and to determine the toxic elements' concentration in the insect meal and diets, 162 hens were randomly allotted to three groups. The control received a corn-soybean meal-based diet; the HI25 and HI50 groups received two diets in which the 25% and 50% of the dietary protein were replaced by the HI protein, respectively. The duodenal and jejunal villi height and villi/crypt were higher (p < 0.01) in the SBM than in the HI groups. The ileal villi height was higher (p < 0.05) in the SBM and HI25 groups than the HI50. The HI50 group exhibited a lower duodenal maltase activity. The intestinal alkaline phosphatase (IAP) activity linearly decreased in the duodenum and jejunum as the dietary insect meal inclusion increased. The HI50 group had a higher acetate and butyrate level than the SBM. The levels of cadmium (Cd), lead (Pb), mercury (Hg), and arsenic (As) lower than the maximum values established by the EU Commission. The 25% soybean protein replacement with Hermetia illucens larvae meal in the diet of laying hens was more suitable and closer to the optimal level than 50%.