Evaluation of oregano (Origanum vulgare) essential oil supplementation on growth performance, digestive enzymes, intestinal histomorphology and gut microbiota of Black Sea salmon, Salmo labrax

This study aimed to determine the effect of dietary oregano (Origanum vulgare) essential oil (EO) on the growth performance, digestive enzyme activity, intestinal histomorphology, and intestinal microbiota of the Black Sea salmon juvenile (Salmo labrax). Fish were fed diets different levels of oregano EO such as 50, 100, 200, and 400 mg kg-1. For this purpose, a total of 675 fish were distributed randomly in triplicate into 5 experiment groups in 15 experiment tanks. Fish with average initial weights of 3.52±0.01 g were fed by hand at 3% of live weight for 90 days. At the end of the study, feeding with oregano EO supplementation did not significantly affect the growth performance of fish. Except for pepsin, there were no significant differences in the activity of digestive enzymes among the control and oregano EO groups. Besides, oregano EO at the doses of 50 or 400 mg kg-1 may have the potential to increase the surface area required for digestion by increasing intestinal villi length. Moreover, all doses of oregano EO showed antimicrobial properties by decreasing the count of lactic acid bacteria in the intestine. Supplementation with 100 and 200 mg kg-1 oregano EO in diets decreased the total coliform, Escherichia coli and lactic acid bacteria counts when compared to the control group. The results showed that oregano EO may positively affect digestion and absorption without adverse effects on the growth performance of Black Sea salmon juvenile. © 2022 Osman Tolga Özel et al., published by Sciendo

Influence of laurel (Laurus nobilis) essential oil on gut function of Black Sea salmon (Salmo labrax) juveniles

The present work investigated the efects of dietary incorporation of laurel (Laurus nobilis) essential oil on the zootechnical performance and digestive physiology of juvenile Black Sea salmon (Salmo labrax). In this trial, 15 fberglass tanks (39×39 cm square and 33 cm high) were used. Forty-fve fsh (3.52±0.01 g) were placed randomly per tank. Fish were fed for 90 days with the diet containing 50, 100, 200, or 400 mg kg−1 laurel (Laurus nobilis) essential oils, respectively. The work was performed in the recirculating aquaculture system (RAS) operating with freshwater. Fish were manually fed 3% level of live weight during the experiment period. Final weight (FW), weight gain (WG), feed conversion rate (FCR), and specifc growth rate (SGR) were not afected by laurel essential oil supplementation. Dietary laurel essential oil (50 mg kg−1) afected positively the surface area of fsh intestinal villus that required for digestion. Both villus height and villus width were afected positively in fsh fed with 50 mg laurel essential oil kg−1. While incorporation with 100 mg laurel essential oil kg−1 increased the total α-amylase enzyme, 50 mg laurel kg−1 increased lipase enzyme. Moreover, 50 mg laurel essential oil kg−1 increased lactic acid bacteria (LAB) count in fsh. Besides, 50 mg laurel essential oil kg−1 reduced the number of total coliform and E. coli

The effects of Fennel (Foeniculum vulgare) Essential Oils on Growth Performance and Digestive Physiological Traits in Black Sea Salmon (Salmo labrax PALLAS 1814) Juveniles

The present study was carried out in the freshwater recirculating aquaculture system to determine the effects of the fennel (Foeniculum vulgare) essential oil on Black Sea salmon (Salmo labrax). Fish were distributed randomly to 50 L experimental tanks, and 45 fish were in each tank. The experiment was triplicate in each group, and the results were averaged. Five diets of equal isonitrogenous and isocaloric content with 50, 100, 200, and 400 mg kg-1 of fennel essential oil were prepared. Fish were fed with diets at the rate of 3% of live body weight four times daily by hand for 90 days. The results revealed that dietary supplementation with fennel essential oil did not have any significant effect on the growth performance. Supplementation with 200 mg fennel kg-1 increased lipase activity in contrast with control group. Supplementation with 400 mg kg-1 fennel showed similar results with the control group in terms of pepsin activity. The intestinal villi length of fish fed 200 mg kg-1 fennel was higher than the control group. The thickness of muscularis in group fed with 50, 100 and 200 mg kg-1 fennel was similar to each other and higher than the control group. Lactic acid bacteria were reduced by fennel essential oil supplementation. Results showed that fennel essential oil can be used in diets of Black Sea salmon without the growth performance

Intestine Villi Morphology of Black Sea Trout (Salmo labrax Pallas, 1814)

This study was conducted to determine the effect of age, sex and weight on the middle intestine villi morphology of fifth-generation Black Sea trout (Salmo trutta labrax Pallas, 1811). The fish were kept in the freshwater ponds (June-October) and marine cages (November-May) to provide the life cycle of species. Intestine tissue samples were taken during period when fish were kept in marine cages. According to the results obtained, middle intestine villi morphology changed depending on age (1, 2, 3, 4 and 5 years old) and different live weight of similar ages (16 months old). The lowest intestine villi development was obtained in 1 years old fish. This was followed by 2 years old fish. The highest intestine villi development was obtained in 3 years old fish. Besides, intestine villi development of high weighted fish was higher than those of low weighted fish. However, it was found that middle intestine villi morphology didn’t changed depending on sex

Farklı protein düzeyli diyetlerle beslenen karadeniz alabalığı (Salmo labrax Pallas, 1814)’nın büyüme performansı ve bağırsak villi morfolojisinin belirlenmesi

This study was conducted to determine changes in the growth performance and distal intestine villi morphology of juvenile Black Sea trout (Salmo labrax) fed diets with three different protein levels (40%, 45% and 50%). It was carried out in two separate sections; freshwater (RAS) and seawater. Juvenile Black Sea trout, having average initial weights of 3.44g (freshwater) and 17.70g (seawater), were fed for 90 days. WG, SGR, FCR and survival weren’t affected by dietary treatment. However distal intestine villi length (VL), width (VW) and length to width ratio (VL/VW) were affected by dietary treatments. Villi length, width and length to width ratio in the fish fed with diet containing 50% protein in freshwater were found to be higher than those fed with other diets. Villi length in the fish fed with diet containing 50% protein in seawater was higher than those fed with other diets. Results showed that feeding with diets contained different protein levels did not effect on growth performance of Juvenile Black Sea trout, but affected on distal intestine villi morphology.Bu çalışma, üç farklı protein düzeyi (%40, %50 ve %55) içeren diyetlerle beslenen yavru Karadeniz alabalığı (Salmo trutta labrax)’ nın büyüme performansı ve bağırsak villi morfolojisindeki değişimleri belirlemek için yapılmıştır. Çalışma tatlısu (kapalı devre) ve deniz suyu olmak üzere iki ayrı yetiştiricilik şartlarında yürütülmüştür. Başlangıç ağırlıkları 3.44 g (tatlısu) ve 17.70 g (deniz suyu) ortalamalarına sahip yavru Karadeniz alabalıkları 90 gün boyunca beslenmiştir. Ağırlık artışı, spesifik büyüme oranı, yem değerlendirme oranı ve yaşama oranı diyetsel uygulamalardan etkilenmemiş, bağırsak villi uzunluğu (VL), genişliği (VW) ve uzunluğun genişliğe oranı (VL/VW) ise diyetsel uygulamalardan etkilenmiştir. Tatlısuda %50 protein içeren diyetle beslenen balıkların VL, VW ve VL/VW değerleri diğer iki diyetle beslenenlerden daha yüksek bulunmuştur. Deniz suyunda ise %50 protein içeren diyetle beslenen balıkların VL değeri diğer iki diyetle beslenenlerden daha yüksek bulunmuştur. Bu sonuçlar, farklı protein düzeylerinin yavru Karadeniz alabalığının büyüme performansı üzerinde herhangi bir etkiye sahip olmadığı, ancak bağırsak villi morfolojisi üzerine etkiye sahip olduğunu göstermiştir

Meristic and morphometric characteristics of the Black Sea salmon, Salmo labrax Pallas, 1814 culture line: an endemic species for Eastern Black Sea

The Black Sea salmon Salmo labrax Pallas, 1814 is an essential species for the Turkish aquaculture sector, given increasing trends of the annual productions. To date, there are few studies on meristic and morphometric characteristics of this species. In this study, the fifth filial generation of the species was specified and studied for meristic and morphometric characteristics. The results obtained in this study were compared with available literature and a similarity was found between the study specimens and wild individuals. The morphological characteristics of any cultured species is valuable especially when a new culture generation is formed and therefore this study outcomes may provide important information to the literature

Improving the reproductive yield of Black Sea Salmon (Salmo labrax PALLAS, 1814) with a selective breeding program

This study aimed to improve some culture characteristics of Black Sea salmon (Salmo labrax) culture generations through a classical selective breeding program. Thus, the success of the applied program was examined by comparing the reproduction time and proportional distribution of the wild broodstock (F-0) individuals with the F-1, F-2, F-3 and F-4 generation broodstocks adapted to the culture conditions. According to the results, gamete uptake from the new generations occurred between October and February. The highest egg uptake was determined for all generations in December. While the difference between wild (F-0) broodstock and F-1, F-2, F-3, and F-4 generations was statistically significant in favor of new generations (P<0.05), the difference was insignificant between hatchery origin-new generations. Mean egg diameters were low in F-2 and F-3 generations, and F-0, F-1 and F-4 generations were found to be higher than the others (P<0.05). It was calculated that the fertilization rate was higher in F-3 and F-4 generations, similar in F-1 and F-2 generations, and lower in F-0 generation than the others (P<0.05) at the end of the study. Through the selection program, it was determined that the adaptation of the species to the culture conditions improved, the reaction to human activities declined, and homogeneous distribution in tanks/ponds was relatively achieved from the F-2 generations. As a result, it has been determined that F-4 generation broodstock have higher culture performance than other generations. Producers of this species should use F-4 broodstock for efficient and economical production.General Directorate of Agricultural Research and Policies (TA-GEM) , Ministry of Agriculture and Forestry, Republic of Turkiye TAGEM/HAYSUD/2001/07/01/20 TAGEM/HAYSUD/2006/09/03/02 TAGEM/HAYSUD/2011/09/01/0