Avanços recentes em nutrição de larvas de peixes

Os requisitos nutricionais de larvas de peixes são ainda mal compreendidos, o que leva a altas mortalidades e problemas de qualidade no seu cultivo. Este trabalho pretende fazer uma revisão de novas metodologias de investigação, tais como estudos com marcadores, genómica populacional, programação nutricional, génomica e proteómica funcionais, e fornecer ainda alguns exemplos das utilizações presentes e perspectivas futuras em estudos de nutrição de larvas de peixes

Elevated sea temperature combined with dietary methionine levels affect feed intake and appetite-related neuropeptide expression in the brains of juvenile cobia (Rachycentron canadum)

This study aimed to determine the impact of elevated temperature combined with different levels of dietary methionine concentrations on feed intake (FI) and brain expression of selected neuropeptides and one receptor involved in appetite control in juvenile cobia (approximately 3.7 g body weight). The genes studies were neuropeptide y, npy; agouti-related protein, agrp; cocaine- and amphetamine-regulated transcript, cart; cholecystokinin, cck and melanocortin 4 receptor; mc4r. The cobia were reared at typical sea water temperature in Vietnam (30 °C) and elevated temperature (34°C; selected as one of the predicted scenarios of climate change). The fish were fed diets with different levels of methionine: deficient (M9; 9.1 g/kg), sufficient (M12; 12.8 g/kg) and surplus (M16, 16.8 g/kg) for 6 weeks (triplicate tanks per treatment). Both dietary methionine concentration and temperature affected FI in cobia. Dietary methionine deficiency (i.e., M9) and elevated temperature reduced FI in cobia. Temperature significantly influenced the mRNA expression of agrp, cart, cck and mc4r. Expression of the orexigenic neuropeptide npy was consistently higher before the meal than after the meal for all diets and at both temperatures. At 30°C, prefeeding levels of npy correlated with both increased methionine levels and FI. The interaction between dietary methionine and temperature on the levels of brain npy expression was significant (P<0.05). There was higher brain expression of agrp, cart and cck in cobia at 34°C than in fish at 30°C, which was correlated with a lower FI. In conclusion, both feeding, temperature and/or dietary methionine levels affected the brain expression of npy and agrp, cart, cck and mc4r. This suggests that these neuropeptides as well as the mc4r receptor are actively involved in adjusting feed intake to compensate for changing energetic demands, as well as metabolic adjustments due to the variable availability of methionine at elevated temperature.publishedVersio

Elevated sea temperature combined with dietary methionine levels affect feed intake and appetite-related neuropeptide expression in the brains of juvenile cobia (Rachycentron canadum)

This study aimed to determine the impact of elevated temperature combined with different levels of dietary methionine concentrations on feed intake (FI) and brain expression of selected neuropeptides and one receptor involved in appetite control in juvenile cobia (approximately 3.7 g body weight). The genes studies were neuropeptide y, npy; agouti-related protein, agrp; cocaine- and amphetamine-regulated transcript, cart; cholecystokinin, cck and melanocortin 4 receptor; mc4r. The cobia were reared at typical sea water temperature in Vietnam (30 degrees C) and elevated temperature (34 degrees C; selected as one of the predicted scenarios of climate change). The fish were fed diets with different levels of methionine: deficient (M9; 9.1 g/kg), sufficient (M12; 12.8 g/kg) and surplus (M16, 16.8 g/kg) for 6 weeks (triplicate tanks per treatment). Both dietary methionine concentration and temperature affected FI in cobia. Dietary methionine deficiency (i.e., M9) and elevated temperature reduced FI in cobia. Temperature significantly influenced the mRNA expression of agrp, cart, cck and mc4r. Expression of the orexigenic neuropeptide npy was consistently higher before the meal than after the meal for all diets and at both temperatures. At 30 degrees C, prefeeding levels of npy correlated with both increased methionine levels and FI. The interaction between dietary methionine and temperature on the levels of brain npy expression was significant (P<0.05). There was higher brain expression of agrp, cart and cck in cobia at 34 degrees C than in fish at 30 degrees C, which was correlated with a lower FI. In conclusion, both feeding, temperature and/or dietary methionine levels affected the brain expression of npy and agrp, cart, cck and mc4r. This suggests that these neuropeptides as well as the mc4r receptor are actively involved in adjusting feed intake to compensate for changing energetic demands, as well as metabolic adjustments due to the variable availability of methionine at elevated temperature.LA/P/0101/2020; QZA-0485 SRV-13/0010info:eu-repo/semantics/publishedVersio

Effect of increased rearing temperature on digestive function in cobia early juvenile

The present study is focused to elucidate the main characteristics of the digestive function of this carnivorous fast-growing fish living at high temperatures. With this aim, we have examined the effects of an increased temperature from 30 to 34 °C on the daily pattern of gastrointestinal pH, enzymatic proteolytic digestive activity and the feed transit time in early juveniles of cobia (Rachycentron canadum), a species living in tropical and subtropical waters with an increasing aquaculture production. Fish were fed two meals a day. Gastric luminal pH was permanently acidic (mean pH values: 2.76-4.74) while the intestinal pH increased from neutral/slightly acidic to slightly alkaline when the digesta was present, with an increasing alkalinity from proximal to distal intestine (mean pH values: 6.05 to 7.69). The temperature did not affect the gastric pH but a slightly higher acidity was induced in the intestine at 34 °C. Pepsin activity showed a daily rhythm at 30 °C with maximum in the middle of the light period, while at 34 °C some hourly changes coinciding with feed adding without a clear daily trend during the 24-h period were observed. The trypsin activity exhibited a daily rhythm at both temperatures with an increase after morning feeding to reach a maximum several hours later. Average pepsin activity during the daily cycle was slightly higher at 34 °C (6.1 and 7.3 U mg-1 BW at 30 and 34 °C respectively), but values were significantly different only at 8 and 24 h after the morning meal. Similarly, the trypsin activity was significantly affected by the temperature only at 8 and 16 h after the morning meal, but daily activity averages were similar (1.20 and 1.29 U g-1 BW at 30 and 34 °C respectively). The partial transit rates of the first meal in the stomach for each period inter-samplings were higher during the first 4-h period and decreased progressively along the rest of the 24-h cycle at both temperatures, but no significant differences were detected at 30 °C. In addition, the transit was notably faster at 34 °C particularly during the first 8 h after feeding, with rates between 100 and 65% of total volume displaced (intake or released) during each 4-h period. In the intestine the transit rate was relatively constant and similar at both temperatures during 12 h after feeding. Then the rates remained very low during the following 12 h. Residence time of the first meal was longer at 30 than at 34 °C, particularly in the stomach (12 h:02 min vs 4 h:54 min respectively). In the intestine the difference was not so large (8 h:18 min vs 6 h:24 min respectively). In a parallel study under same conditions, cobia reared at 30 °C grew faster and showed a more favorable feed conversion ratio than those at elevated temperature (34 °C). The present results indicate that at 34 °C, a subtle increase of proteolytic activity cannot compensate for the faster gut transit rate. Therefore, 30 °C is more appropriate temperature for the early on-growing of cobia because at higher temperatures the digestion efficiency decrease being one of the causes for a lower growth.Agência financiadora European Union (EU) 691150 MINECO, Spain + FEDER/ERDF contribution EFISHDIGESTAGL2014-52888 European Social Fund, the Operational Programme Human Potential IF/00482/2014/CP1217/CT0005 Portuguese Foundation for Science and Technology Portuguese Foundation for Science and Technology UDI/Multi/04326/2013 Norwegian Agency for Development Cooperation NORHED QZA-0485 SRV-13/0010info:eu-repo/semantics/publishedVersio

Consistency of individual variation in feeding behaviour and its relationship with performance traits in Nile tilapia Oreochromis niloticus

Feed intake is commonly used as one of the most important performance indicators in fish. However, very little is known about the behavioural processes involved in ingesting food such as meal duration, feeding frequency and latency to start eating. This study aims at the characterization of feeding behaviour in Nile tilapia Oreochromis niloticus in terms of consistency of individual differences over time and correlation with performance traits. Seventy-two individuals were individually housed for 27 days. These fish had three different weight (age) categories: low (initial body weight: 61.32 ± 5.97 g), middle (151.19 ± 4.26 g) and high (265.90 ± 19.13 g), each containing 24 fish. Daily feed intake was recorded per fish. On days 8, 15 and 21 feeding behaviour was assessed by measuring the latency to start feeding (LAT, min), the total feeding time (TFT, min) and the number of feeding acts (NFA). In the end of the experimental period, fish were weighed and individual growth rate and feed efficiency (measured as residual feed intake) determined. Results show that feeding latency and the number of feeding acts have significant repeatability estimates for all weight classes. These estimates were, however, low in magnitude and decreased as the weight class increased. The correlation between the different feeding behaviours showed that individuals that are more active during feeding (higher NFA) on average, start to consume their feed earlier (lower LAT) and for longer periods (higher TFT). The number of feeding acts was significantly correlated with both feed intake and growth in all size classes. The residual feed intake was correlated with feeding latency only in the small weight class. These results showed that individual differences in feeding behaviour have low repeatability estimates and can partly explain differences in performance traits in juveniles of Nile tilapi

Feeding behavior and stress response explain individual differences in feed efficiency in juveniles of Nile tilapia Oreochromis niloticus

Feed efficiency is a trait of enormous importance in any animal production sector including aquaculture. Individuals that are more feed efficient need to use less feed to achieve similar growth rates as compared to less efficient individuals. Considering that feed represents the largest cost of production and one of the main causes for the ecological footprint of a farm, more knowledge on the extent of individual differences in feed efficiency and underlying physiological processes are needed. This study is the first to investigate individual differences in feed efficiency, measured as residual feed intake and its relationship with feeding behaviour and stress response in one of the most important farmed fish, the Nile tilapia. The individual feed intake of twenty-four juvenile of Nile tilapia was followed during 57 days. Fish were fed until apparent satiation with a commercial feed twice per day. Individual feed behavior was registered once per week and consisted on measuring the latency to start feeding (LAT, min), total feeding time (TFT, min) and the number of feeding acts (NFA, min). Blood samples for plasma cortisol was taken at the end of the experiment (control, indicative of undisturbed levels) and after a stress test (netting), 15 days after the previous sampling. Individual growth rates and residual feed intake were determined at the end of the experiment. Results show pronounced individual differences in residual feed intake as well as a significant correlation with both feeding behavior (feeding latency, total feeding time and number of feeding acts) and stress (cortisol) response. Cortisol levels obtained after the stress test and feeding behavior could explain differences in residual feed intake by 4%. These results show that individuals with higher feeding activity and higher cortisol response are less efficient fish. This suggests that individual differences in feeding activity and stress response explain part of the differences in feed efficiency by explaining variance in maintenance energy expenditure

Characterization of mesenchymal stem cells derived from equine adipose tissue

Stem cell therapy has shown promising results in tendinitis and osteoarthritis in equine medicine. The purpose of this work was to characterize the adipose-derived mesenchymal stem cells (AdMSCs) in horses through (1) the assessment of the capacity of progenitor cells to perform adipogenic, osteogenic and chondrogenic differentiation; and (2) flow cytometry analysis using the stemness related markers: CD44, CD90, CD105 and MHC Class II. Five mixed-breed horses, aged 2-4 years-old were used to collect adipose tissue from the base of the tail. After isolation and culture of AdMSCs, immunophenotypic characterization was performed through flow cytometry. There was a high expression of CD44, CD90 and CD105, and no expression of MHC Class II markers. The tri-lineage differentiation was confirmed by specific staining: adipogenic (Oil Red O), osteogenic (Alizarin Red), and chondrogenic (Alcian Blue). The equine AdMSCs are a promising type of adult progenitor cell for tissue engineering in veterinary medicine.O uso de células tronco tem demonstrado resultados promissores na terapia da tendinite e osteoartrite na medicina equina. O objetivo deste trabalho foi caracterizar as células tronco mesenquimais derivadas do tecido adiposo (AdCTMs) em cavalos através da (1) avaliação da capacidade das células progenitoras para realizar a diferenciação adipogênica, osteogênica e condrogênica; e (2) através da análise por citometria de fluxo, utilizando os marcadores stemness relacionados: CD44, CD90, CD105 e MHC de Classe II. Cinco cavalos sem raça definida, de 2 a 4 anos de idade foram utilizados para a coleta do tecido adiposo da base da cauda. Após o isolamento e cultivo das AdCTMs, a caracterização imunofenotípica foi realizada pela citometria de fluxo. Houve alta expressão dos marcadores CD44, CD90 e CD105, e não houve expressão do MHC Classe II. A diferenciação foi confirmada pela coloração específica: adipogênica (Oil Red O), osteogênico (Alizarin Red), e condrogênico (Alcian Blue). As AdCTMs são um tipo promissor de células progenitoras adulta para a engenharia tecidual na medicina veterinária.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP