Red Tilapia Research Articles

Bacterial community diversity, abundance, and composition of rearing water and red tilapia gills from open river cages and earthen ponds in Central Thailand

Bacterial community diversity, abundance, and composition of rearing water and red tilapia gills from open river cages and earthen ponds in Central Thailand

Optimizing Convolutional Neural Networks, XGBoost, and Hybrid CNN-XGBoost for Precise Red Tilapia (Oreochromis niloticus Linn.) Weight Estimation in River Cage Culture with Aerial Imagery

Accurate feeding management in aquaculture relies on assessing the average weight of aquatic animals during their growth stages. The traditional method involves using a labor-intensive approach and may impact the well-being of fish. The current research focuses on a unique way of estimating red tilapia’s weight in cage culture via a river, which employs unmanned aerial vehicle (UAV) and deep learning techniques. The described approach includes taking pictures by means of a UAV and then applying deep learning and machine learning algorithms to them, such as convolutional neural networks (CNNs), extreme gradient boosting (XGBoost), and a Hybrid CNN-XGBoost model. The results showed that the CNN model achieved its accuracy peak after 60 epochs, showing accuracy, precision, recall, and F1 score values of 0.748 ± 0.019, 0.750 ± 0.019, 0.740 ± 0.014, and 0.740 ± 0.019, respectively. The XGBoost reached its accuracy peak with 45 n_estimators, recording values of approximately 0.560 ± 0.000 for accuracy and 0.550 ± 0.000 for precision, recall, and F1. Regarding the Hybrid CNN-XGBoost model, it demonstrated its prediction accuracy using both 45 epochs and n_estimators. The accuracy value was around 0.760 ± 0.019, precision was 0.762 ± 0.019, recall was 0.754 ± 0.019, and F1 was 0.752 ± 0.019. The Hybrid CNN-XGBoost model demonstrated the highest accuracy compared to using standalone CNN and XGBoost models and could reduce the time required for weight estimation by around 11.81% compared to using the standalone CNN. Although the testing results may be lower than those from previous laboratory studies, this discrepancy is attributed to the real-world testing conditions in aquaculture settings, which involve uncontrollable factors. To enhance accuracy, we recommend increasing the sample size of images and extending the data collection period to cover one year. This approach allows for a comprehensive understanding of the seasonal effects on evaluation outcomes.

The Effect of Dietary Supplementation of Ulva reticulata Extract on Reproduction of the Male Red Tilapia (Oreochromis sp.)

The Effect of Dietary Supplementation of Ulva reticulata Extract on Reproduction of the Male Red Tilapia (Oreochromis sp.)

Influence of astaxanthin-enriched Haematococcus pluvialis microalgae on the growth efficacy, immune response, antioxidant capacity, proinflammatory cytokines, and tissue histomorphology of hybrid red tilapia

Influence of astaxanthin-enriched Haematococcus pluvialis microalgae on the growth efficacy, immune response, antioxidant capacity, proinflammatory cytokines, and tissue histomorphology of hybrid red tilapia

Comparative impact of replacing fish meal with azolla on growth, water quality, and physiology of red tilapia fingerlings at varying salinities.

A 210-day experiment to assess the efficacy of substituting azolla plant powder at levels of 0, 20, 40, and 60% for fish meal on red tilapia fingerlings (RTF, initial weight of 18.23 ± 0.12 g) performance under salinity levels of 5, 18, and 28ppt. Among the various conditions, RTF-fed 20% azolla at 28 and 5ppt salinity showcased the highest specific growth rate (SGR), whereas the lowest SGR was observed in fish-fed 60% azolla at 5ppt salinity. Upon azolla incorporation, noteworthy elevations in phytoplankton, zooplankton, dissolved oxygen (DO), pH, NH3, and NO3 were noted and conversely, azolla introduction led to decreased NH4 and NO2 concentrations in all salinity levels. Further, a significant (p < 0.05) interaction between azolla levels and water salinity (S×A) significantly impacted the hematological parameters of RTF. The highest levels of superoxide dismutase (SOD), catalase (CAT), and total protein (TP) were found in RTF-fed 20% azolla at 28ppt salinity, while the lowest CAT and TP levels occurred in RTF-fed 60% azolla at 5ppt salinity. The highest aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were recorded in the RTF group fed 60% azolla at 5ppt salinity, with the lowest values seen in the group given 20% azolla at 28ppt salinity. RTF fed a 20% azolla diet at 18ppt salinity exhibited the highest lysozyme value, in contrast to the lowest value observed in the RTF group fed the control diet at 18ppt salinity. In conclusion, this study recommends the utilization of azolla at inclusion levels ranging from 20 to 40%, as it has the potential to notably enhance the immune system and elevate the survival rate of RTF.

Impact of a varied combinatorial mixture of β-1, 3 glucan and fructooligosaccharides on growth performance, metabolism, intestinal morphometry, expression of antioxidant-related genes, immunity, and protection against Vibrio alginolyticus in Red tilapia (Oreochromis niloticus x O. mossambicus)

Immunosaccharides such as β-glucans and fructooligosaccharide (FOS) strengthen the host’s immune responses. This study examined the influences of three levels of the β-1, 3 glucan-FOS combination on Red tilapia performance. Four diets were prepared: T0 as a control, while T0.5, T1, and T1.5 indicate the addition of β-1, 3 glucan-FOS mixture at 0.5%, 1%, and 1.5%, respectively. Then, 240 red Tilapia (Oreochromis niloticus x O. mossambicus) (weight 6.1 ± 0.07gm) were allocated into four groups, and every group was fed tested diets for 56 days. After the feeding trial, growth parameters, erythrogram profile, liver and kidney function testes, glucose, histopathological analysis, and gene expressions for antioxidants, catalase (CAT) and glutathione peroxidase (GPX) besides growth hormone (GH) and insulin-like growth factor 1 IGF1-related markers were assessed. Red tilapia fed T0.5, T1, and T1.5 exhibited consistent growth, survival rate, and homeostasis compared with the control group. Different supplement concentrations displayed varying levels of responses. The hepatorenal biomarkers (alanine transaminase (ALT = SGPT) and aspartate transaminase (AST = SGOT), alkaline phosphatase (ALP = ALK), urea, and creatinine) and glucose showed a significant reduction in the supplemented groups compared with the control, especially in the T1 and T1.5 groups. The intestinal morphometric study revealed that fish group fed on T1 represented the best result, whereas group T1.5, followed by group T0.5, was moderately treated, compared to the control. The real-time quantitative reverse transcription PCR (qRT-PCR) analysis displayed up-regulated expression of antioxidant and growth-correlated genes in the T1.5 groups. After 56 days, the β-1,3 glucan-FOS fed groups also exhibited an increase in survival rates compared to the control when challenged with a pathogenic Vibrio alginolyticus. Current findings suggest that inclusion of β-1,3 glucan-FOS in diets could enhance red tilapia biochemical parameters, growth, and protection against pathogenic V. alginolyticus infection.

Characterization of Lactococcus garvieae and Streptococcus agalactiae in cultured red tilapia Oreochromis sp. in Thailand.

Acute mortality with clinical symptoms of streptococcal-like infections was observed in red tilapia Oreochromis sp. cultured in floating cages in Prachin Buri Province, Thailand, during May 2023. Herein, we identified an emerging pathogen, Lactococcus garvieae, as the etiological agent. After bacterial isolation from the brain and kidney of diseased fish, identification was performed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and the VITEK 2 system. Sequencing of the 16S ribosomal RNA (rRNA) gene and phylogenetic analysis were applied to confirm bacterial species. Antimicrobial susceptibility testing was conducted. Histopathological findings in the brain, kidney, spleen, liver, and heart were evaluated. From 20 fish samples, L. garvieae (n = 18 isolates) and Streptococcus agalactiae (n = 2 isolates) were identified. A phylogenetic tree of the 16S rRNA gene revealed that Thai isolates of either L. garvieae or S. agalactiae clustered with reference piscine isolates from intercontinental locations. Our isolates showed resistance against quinolones while being susceptible to other antimicrobials. Histopathological changes demonstrated severe septicemic conditions, with more invasive lesions-especially in the heart and liver-being apparent in L. garvieae-infected fish compared to S. agalactiae-infected fish. This study represents the first reported outbreak of L. garvieae with a concurrent S. agalactiae infection in farmed red tilapia in Thailand.

Feasibility of molasses-fermented banana peel as a protein source in practical diet for hybrid tilapia (Oreochromis spp.): effect on growth and feed efficiency

This study aims to increase the utilization of banana peels, a local agricultural by-product, by improving nutrient value and partially reducing the presence of anti-nutritional factors (ANFs) as an alternative ingredient in fish feed. The feasibility of molasses-fermented banana peels (MFBP) as a protein source in a practical diet for hybrid tilapia (Oreochromis spp.) fries was investigated. Five isonitrogenous experimental diets containing 0 (control), 25, 50, 75, and 100% substitution levels of fish meal by MFBP were formulated. Twenty tilapia fries per group with three replicates were fed for eight weeks. The growth performance and feed efficiency values of fish were recorded and evaluated. Fish fed with 0, 25, and 50% MFBP levels showed significantly higher growth parameters, survival rate, and feed utilization efficiency than those fed with 75 and 100% MFBP levels. Although the control diet produced better growth performance and feed utilization efficiency than MFBP-based diets there was no significant difference between fish fed with the control diet and the low MFBP levels (0-50%) diet. Based on the present findings, it could be concluded that the molasses-fermented banana peels (MFBP) could efficiently replace the fishmeal by up to 50% without affecting the growth performance of red tilapia.

Effect of prolonged photoperiod on growth, gonadal development, sex ratio, and skin coloration of red tilapia (O. mossambicus × O. urolepis hornorum)

Farming of red tilapia is one promising direction in aquaculture. The objective of this study was to investigate the impact of long-day photoperiod on the growth performance, reproductive parameters, maturity, sex ratio, β-carotene content, and skin coloration of red tilapia. Early life larvae were allocated into three treatment groups in triplicates: T1 = control group (12L:12D), T2 = long-day group (18L:6D), and T3 = continuous illumination group (24L:0D) for 90 days. By the end of the experiment, gonadosomatic index (GSI), relative fecundity, steroid hormones, maturity stages, sex ratio, and ovarian and testicular histology were examined; also, growth performance, survival rate, skin color, and total β-carotene content were measured. The results indicated that GSI% and serum testosterone (T) in T3 group significantly increased with greater amount of spermatozoa of male fish. Also, growth parameters and HSI% in female fish displayed significantly increased for T3 group. Females in group T2 showed significant elevation in GSI%, relative fecundity, and estradiol (E2) with higher number of mature stage. Continuous light group (T3) showed shifted male sex ratio, while female percentage was higher in T2 group. The total β-carotene content of T3 group showed significant elevation with less number of black spots. This study demonstrated that continuous light manipulation during red tilapia early life could stimulate the growth and enhance coloration by reducing black spots that significantly affects economic profitability. Long-day application was effective in female reproductive performance and maturity. This study also served as an important reference for red tilapia aquaculture.

Comparative Study of Growth Performance of Three Tilapia Strain in Intensive Culture System

High stocking density is an important factor in cultivation to increase the eficency if fish farming for nutrition requirements. High stocking density generally impact on fish physiology and growth performance. However, many studies on individual fish have different growth perfromance from different strain. Some technology had been developed to optimize tilapia production in high stocking density. This study aimed to determine the growth performance of three different strain of tilapia (red tilapia, nirwana tilapia, and jatimbulan tilapia) reared in 20 m3 of round tarpaulin with additional of microbubble generator. This study used an intensive system with 100 fish/m3 of stocking density. The results showed that the microbubble generator was able to increase the carrying capacity of water quality such as increasing dissolved oxygen in the waters, temperature and pH. The high content of dissolved oxygen in the water significantly increasing the growth of tilapia. The highest weight was found in red tilapia with a final weight of 199.56 ± 0.05 gr, followed by Nirwana tilapia with 176.59 ± 0.10 gr, and Jatimbulan tilapia with 153.91 ± 0.06 gr. In addition, the high content of dissolved oxygen in the waters also affect the rearing period of tilapia.

The Effect of Soaking Zeolite Stones and Activated Charcoal on the Survival of Red Tilapia (Oreochromis sp.) Raised in Oil Palm Plantation Wastewater (Elaeis guineensis)

Ikan nila merah merupakan salah satu jenis ikan air tawar yang memiliki tingkat toleransi lingkungan yang luas, termasuk pada lingkungan dengan toksisitas tinggi. Penelitian ini bertujuan untuk mengetahui dan mengevaluasi pengaruh perendaman batu zeolit dan arang aktif terhadap kelangsungan hidup ikan nila merah yang dipelihara di air limbah perkebunan kelapa sawit. Metode yang digunakan dalam penelitian ini adalah metode eksperimen RAL (Rancangan Acak Lengkap) dengan 4 perlakuan dan 3 ulangan. Perlakuan perendaman yang digunakan adalah P1 tanpa dosis/kontrol/10 L air limbah, P2 dengan takaran zeolit dan arang aktif dengan perbandingan 50 gr : 50 gr/10 L air limbah, P3 dengan takaran zeolit dan arang aktif. arang dengan perbandingan 100 gr:100 gr/10 L air limbah, dosis P4 zeolit dan arang aktif dengan perbandingan 150 gr:150 gr/10 L air limbah. Data yang diperoleh dianalisis dengan menggunakan uji Anova dan Duncan. Hasil penelitian menunjukkan bahwa perendaman pada batu zeolit dan arang aktif berpengaruh terhadap kelangsungan hidup ikan nila merah. Kelangsungan hidup tertinggi terdapat pada perlakuan P3 dengan hasil 90±10b, disusul P4 dengan hasil 83,33±5,77b, kemudian disusul P2 dengan hasil 76,67±5,77b, dan kelangsungan hidup terendah terdapat pada P1 dengan hasil 76,67±5,77b. hasil 66.67±5.77a.Kata Kunci: Nila merah, kualitas air, zeolit, arang aktif, kelangsungan hidup.

Enhancement of Growth Performance and Body Coloration Through The Inclusion of Torch Ginger Powder in The Feed of Red Tilapia (Oreochromis sp.)

Red tilapia (Oreochromis sp.) is a highly produced aquaculture fish among freshwater species. Coloration is an important factor in determining consumer preferences. Therefore, an 8-week experiment was conducted to enhance the growth performance and body coloration through the inclusion of torch ginger in the feed of red tilapia. Five experimental feeds were prepared from commercial feed (crude protein: 34%, crude lipid: 5%) containing torch ginger powder at 2.5, 5.0, 7.5, and 10% (T1, T2, T3, &amp; T4) inclusion levels while feeding without torch ginger act as a control (T0). Red tilapia (Initial body weight: 0.4±0.1g; Initial total length: 4.0±0.1cm) were distributed at stocking number 20 fish/tank into fiberglass tanks with a capacity of 80 L and triplicates for each treatment. The fish were fed with experimental feeds until satiation. The growth of fish was significantly higher (P&lt;0.05) when the fish fed with T1, T2, and T3 compared to control treatment T0. Moreover, the feed intake was significantly increased (P&lt;0.05) when the torch ginger powder was added to the experimental feeds. In addition, the FCR was significantly better (P&lt;0.05) when the fish fed on T1, T2, and T3 compared to T0. The inclusion of torch ginger powder in the feed did not significantly affect (P&lt;0.05) the body protein and lipids of the experimental fish. The increment of redness was significantly higher (P&lt;0.05) when the fish fed with T1, T2, T3, and T4 compared to T0. However, it showed a declining trend of redness when the inclusion of torch ginger increased to 5.0% and above. Thus, the present study suggested that the inclusion of torch ginger powder improved the performance and enhanced the body coloration of juvenile red tilapia. However, a further increase of torch ginger powder by more than 2.5% did not help in the enhancement of the body coloration.

Comparison of Water Quality Prediction for Red Tilapia Aquaculture in an Outdoor Recirculation System Using Deep Learning and a Hybrid Model

In modern aquaculture, the focus is on optimizing production and minimizing environmental impact through the use of recirculating water systems, particularly in outdoor setups. In such systems, maintaining water quality is crucial for sustaining a healthy environment for aquatic life, and challenges arise from instrumentation limitations and delays in laboratory measurements that can impact aquatic animal production. This study aimed to predict key water quality parameters in an outdoor recirculation aquaculture system (RAS) for red tilapia aquaculture, including dissolved oxygen (DO), pH, total ammonia nitrogen (TAN), nitrite nitrogen (NO2–N), and alkalinity (ALK). Initially, a random forest (RF) model was employed to identify significant factors for predicting each parameter, selecting the top three features from routinely measured parameters on the farm: DO, pH, water temperature (Temp), TAN, NO2–N, and transparency (Trans). This approach aimed to streamline the analysis by reducing variables and computation time. The selected parameters were then used for prediction, comparing the performance of convolutional neural network (CNN), long short-term memory (LSTM), and CNN–LSTM models across different epochs (1000, 3000, and 5000). The results indicated that the CNN–LSTM model at 5000 epochs was effective in predicting DO, TAN, NO2–N, and ALK, with high R2 values (0.815, 0.826, 0.831, and 0.780, respectively). However, pH prediction showed lower efficiency with an R2 value of 0.377.

Immersion of nanostructured lipid carriers loaded with 17-alpha methyltestosterone for masculinization of red tilapia (Oreochromis sp.)

The present study aimed to develop novel masculinization agents for enhancing sex-reversal in red tilapia (Oreochromis sp.) by immersion administration using 17α-methyltestosterone-loaded nanostructured lipid carriers (MT-NLC). Moreover, the surface charge of the MT-NLC was modified with chitosan (CS-MT-NLC) to improve their mucoadhesive property. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used to characterize the morphology of the nanoparticles. Furthermore, we assessed the toxicity associated with immersion-induced masculinization in red tilapia. Subsequently, we examined alterations in gill morphology, determined the percentage of masculinization, analyzed their length-weight relationship, and investigated the expression of genes related to sex differentiation. MT-NLC had an average size, polydispersity index, and negatively charged surface of 140.8 ± 2.6 nm, <0.2, and −26.9 ± 0.3 mV, respectively, with higher stability at 4 °C and 25 °C compared to CS-MT-NLC. The release mechanisms of NLC and CS-NLC were regulated by diffusion processes, which were characterized using Avrami's equation. In contrast, the release mechanism of non-encapsulated MT (MT-ET) was governed by burst release kinetic. Furthermore, tests assessing mucin binding confirmed that CS-MT-NLC, with a positive charge, exhibited superior mucoadhesive properties compared to MT-NLC, with a negative charge. Importantly, CS-MT-NLC immersion was found to be toxic to red tilapia fry; therefore, it has been discontinued for further experiments. The immersions of both MT-NLC and MT-ET were non-toxic to red tilapia fry, with an LC50 exceeding 800 μg/L, and the morphological appearance of the gills after treatment was normal. The MT-NLC-400 and MT-ET-800 groups exhibited elevated expression levels of dmrt1 and sox9 compared to cyp19a1a and soxl2. These higher expression levels corresponded to significantly higher percentages of males (98.3% and 95.7%) in both the MT-NLC and MT-ET groups compared to the control group (54.7%). The MT-NLC and MT-ET groups displayed a negative allometric growth behavior in red tilapia fry, with a relative condition factor > 1. Adopting MT-NLC-400 immersion treatment for masculinizing red tilapia could serve as a beneficial strategy for commercial tilapia farms to reduce the required dosage and the time needed to treat fish.

Zootechnical Performance and Bromatological Composition of the Flesh of Oreochromis sp (Red Tilapia) Fed with Local Feed Supplemented with Afrostyrax lepidophyllus Seed Powder

Zootechnical Performance and Bromatological Composition of the Flesh of Oreochromis sp (Red Tilapia) Fed with Local Feed Supplemented with Afrostyrax lepidophyllus Seed Powder

Role of Vitamin E Supplementation on the Reproductive and Growth Performance, Hormonal Profile and Biochemical Parameters of Female Hybrid Red Tilapia

The present study aimed to evaluate the effect of vitamin E (VE) supplementation on the reproductive and growth performance, hormonal profile, and biochemical parameters of female hybrid red tilapia before spawning season. Seventy-two female hybrid red tilapia were caught with an average body-weight 272.56 ± 34.84g and an average total length 24.3 ± 2.5 cm. Healthy fish were distributed equally into 4 treatments supplemented with (0, 50, 100, 200 mg/kg) of VE given for 8 weeks. VE significantly improved weight gain, length gain, specific growth rate, average daily gain, feed conversion ratio, and protein efficiency ratio. 50 mg of VE/kg diet could improve the viscerosomatic index, hepatosomatic index, and gonadosomatic index. Also, it could improve the parameters of biochemical (aspartate aminotransferase, alanine transaminase, total protein, albumin, globulin, triglyceride, and alkaline phosphatase) and haematology (total erythrocytic and leucocytic count, hematocrit and hemoglobin) and increase FSH, LH, E2 and, progesterone concentrations significantly. The conclusion revealed that the addition of 50 mg of VE /kg diet has a beneficial impact on reproductive and growth performance, hormonal profile, and biochemical parameters of female hybrid red tilapia. So, it is advisable for adding 50 mg/kg of vitamin E to the fish diet before the spawning season (pre-spawning).

Relationship Between Abundance of Clamydomonas spp and Chlorella spp on Clinical Performance of Red Tilapia Oreochromis niloticus in Silvofishery Ponds

Abstract Chlamydomonas spp. and Chlorella spp. are plankton genera that can be used to determine the level of balance in the aquatic environment. The purpose of this study is to determine the abundance of plankton Chlamydomonas spp. and Chlorella spp. and its relation to the clinical performance of red tilapia in silvofishery ponds. The research method used is an ex post facto causal design with random sampling. The results showed that the water quality in the silvofishery ponds was very good, except for the nitrate parameters of 0.00-1.50 mg/L and salinity of 2-11 gr/L, which exceeded the quality standards. In the silvofishery ponds, 5 plankton classes were found, namely Chlorophyceae, Cyanophyceae, Chrysophyceae, Protozoa, and Dinophysis, consisting of 15 genera. The dominant class Chlorophyceae had an abundance of 2.88E+06 cells/ml. The class Chlorophyceae is dominated by Chlorella spp. (2.63E+06 cells/ml) and Chlamydomonas spp. (2.20E+05 cells/ml). The abundance of Chlamydomonas spp. in silvofishery ponds is closely related to phosphate solubility (0.988). Based on observations of clinical symptoms on the eyes, gills, and fins of fish, no disease infections or physical abnormalities were found in the fish cultured in silvofishery ponds. Fish tend to live well with a growth rate of 0.44 g/day. The aquatic ecosystem of the silvofishery pond, which is dominated by the plankton Chlorella spp. and Chlamydomonas spp., had a good effect on the performance and condition of the farmed fish. This study concludes that the abundance of Chlamydomonas spp. and Chlorella spp. was very dominant compared to other plankton genera. The presence of Chlamydomonas spp. and Chlorella spp. illustrates good and stable environmental conditions in silvofishery ponds, followed by no clinical signs of disease infection in the fish reared during the study period.

Antioxidant and antiproliferative activity of enzymatic hydrolysates from red tilapia (Oreochromis spp.) viscera

The antioxidant and antiproliferative activity of red tilapia (Oreochromis spp.) viscera hydrolysates (RTVH) was evaluated. For that, the hydrolysates was applied to three cancer cell lines (HepG2, Huh7 and SW480) and the control (CCD-18Co). Finally, the line on which the hydrolysate had the greatest effect (SW480) and the control (CCD-18Co) were subjected to the ApoTox-Glo Triplex Assay to determine apoptosis, toxicity, and cell viability. The result showed that hydrolysate had a dose-dependent cytotoxic effect selective on the three cancer cell lines, compared to the control cells. There is a relationship between the antioxidant capacity of RTVHs and their antiproliferative capacity on cancer cells evaluated, which achieved cell viability by action of RTVH of 34.68 and 41.58 and 25.41 %, to HepG2, Huh7 and SW480, respectively. The action of RTVH on cancer cell line SW480 is not due to the induction of apoptosis but to the rupture of the cell membrane.

Evaluation of the protective efficacy of inactivated vaccines from wild-type Streptococcus agalactiae (GBS) on red Tilapia (Oreochromis sp.)

Streptococcus agalactiae causing eye edema and hemorrhagic disease on red tilapia is a serious problem for the aquaculture industry. The experiment was conducted to evaluate the protective efficacy of formalin-inactivated S. agalactiae AG5 (Group B Streptococcus, GBS) vaccine on red tilapia (Oreochromis sp.) by feeding method. The experiment was arranged in a completely randomized design and fish were fed vaccine-mixed feeds with different concentrations of 104; 105; 106; 107; 108 CFU/g of feed, respectively. At 3 weeks after being fed vaccines, fish were infected with wild-type S. agalactiae AG5 strain by injecting 100 µL of medium containing a dose of LD50 = 6.87 × 103 CFU/mL into the abdomen. The effectiveness of relative percentage survival (RPS) protection was determined within 1 week after infection. Samples of dead fish were recorded with symptoms and brain samples were cultured on TSA medium and incubated at 28oC for 24 h. The colonies were examined using PCR test with F1/IMOD-specific primer pairs. The results showed that the inactivated S. agalactiae AG5 (GBS) vaccine had the highest protective effect on red tilapia of 50% at the vaccine dose of 107 CFU/g of feed. The study also showed that red tilapia had an immune response with the mean antibody titers in the vaccine treatments, ranging from 2.24 ± 0.20 to 3.59 ± 0.42 (P &lt; 0.05).

Ecological footprint of different laying hen production systems in San Jeronimo municipality Antioquia, Colombia

In recent years, fish production has increased worldwide due to population growth and consumer interest in this type of product, proving an increase in the waste generated, with concomitant negative impact on the environment. Ecological footprint methodology is one of the sustainability indicators most used for assessing process environmental impact. This technique quantifies the effect of anthropogenic activities on the environment concerning water, forest products, infrastructure and carbon footprint, providing integral, comparable and reliable results. In this study, the environmental impact generated by taking advantage of red tilapia (Oreochromis Spp.) viscera to produce chemical silage and its implementation in the feeding of laying hens was determined, using the ecological footprint methodology as an indicator of sustainability. The productive system consisted of a red tilapia (Oreochromis ssp.) production farm located in the municipality of San Jerónimo, Antioquia (Colombia). The productive variables of the laying hens, laying percentage, egg weight and feed conversion ratio were evaluated. This chemical silage production process generates a reduction of 1.493 kg of CO2 per month compared to that generated by fresh viscera and are discharged into shallow dumps. Additionally, the main categories that generate the greatest impact on the production system are the use of natural resources and wastewater disposal. On the other hand, the productive variables of laying hens of the Isa Brown breed were not significantly affected by the inclusion of chemical silage at the 95% significance level, maintaining the percentage of laying and improving feed conversion. It was concluded that the use of fish by-products to produce feed for laying hens generates a reduction in the environmental load when compared to conventional waste disposal processes (landfill disposal). Red tilapia (Oreochromis Spp.) viscera chemical silage can be used as an alternative protein substitute in feeding laying hens for improved production performance. Key words: Ecological footprint, fish waste, layer hen, chemical silage, wastewater