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Abstract In this study, selectively bred rainbow trout (Oncorhynchus mykiss) with improved fillet yield were reared on three commercially available diets that varied in dietary lipid content: low lipid (LL, 18%), moderate lipid (ML, 24%), and high lipid (HL, 29%–33%). The objective was to determine if a genotype by diet interaction affects product yield and muscle quality traits in high fillet yield (HY) and low fillet yield (LY) lines of rainbow trout. Main effects of the genetic line (p

In this study, selectively bred rainbow trout (Oncorhynchus mykiss) with improved fillet yield were reared on three commercially available diets that varied in dietary lipid content: low lipid (LL, 18%), moderate lipid (ML, 24%), and high lipid (HL, 29%–33%). The objective was to determine if a genotype by diet interaction affects product yield and muscle quality traits in high fillet yield (HY) and low fillet yield (LY) lines of rainbow trout. Main effects of the genetic line (p < 0.05) were observed for viscera yield, carcass yield, and fillet yield that were more favorable in the HY line. Analysis of muscle quality traits indicated that selection for fillet yield did not compromise fillet quality. A genotype by diet interaction (p < 0.05) was observed for viscera lipid content at the 2 kg harvest, for which viscera lipid content was similar between the HY and LY lines for the LL and HL diets, but greater (p < 0.05) in the LY line for the ML diet. Collectively, these findings indicate that higher product yields in the selectively bred HY line of rainbow trout will persist across diets with variable crude lipid/energy contents. [ABSTRACT FROM AUTHOR]

In the present work, we studied ten new productive traits in meagre (Argyrosomus regius), comprising three related to the carcass (cNiT) and seven related to morphometric (mNiT) characteristics. We harnessed non-invasive technology (NiT) by means of the IMAFISH_ML software. This tool's potential was leveraged on an industrial scale, encompassing the evaluation of 612 fish from two distinct rearing systems (marine cages and indoor tanks) at the time of harvest. Each fish underwent digital photography for morphometric measurements, manual weighing, and was manually eviscerated and filleted to calculate the carcass and fillet yield. Subsequently, the principal genetic parameters were estimated. The heritabilities for the growth traits were moderate (0.34 and 0.39 for TL and BW), whilst those for the cNiT traits ranged from medium to low (0.32–0.27). For the mNiT, they demonstrated a medium to low range (0.15–0.37), whereas the carcass and fillet yield heritabilities were considered to be medium to high (0.32 and 0.31). Most of the genetic correlations between the growth, NiT, and yield traits were not estimated accurately due to the limited data. As was expected, we observed predominantly high and positive correlations between the growth and mNiT. A genetic correlation to highlight was the fillet yield with the fish maximum height (0.87 ± 0.23) and with the head height (0.87 ± 0.24). This suggests that indirect selection using NiT could improve the growth and yield traits. Employing a multi-trait selection approach enables us to capture a broader spectrum of genetic variability and to potentially identify individuals with superior genetic potential. The use of image analysis software ensures objective and precise measurements, thereby reducing the potential for human error or bias during the selection process. Further studies should be carried out to improve the accuracy of the estimates, especially those of the genetic correlations. [ABSTRACT FROM AUTHOR]

Ultrasonography has been used to collect data on internal structures in terrestrial species for many decades and has proven an important tool for measuring meat yield-related phenotypes. However, application of this technique to selective breeding of aquaculture species is recent, and its use for recording yield traits of economic importance has not yet been standardized for many species. The aim of the present study was to standardize ultrasound image collection methods for assessment of fillet yield phenotypes in Nile tilapia. Ultrasound images were obtained from 30 tilapia with mean weight of 645 g (± 165.89) using the VINNO Q device. Data on fillet cross-sectional area at three standard points along the length of the fish were analyzed with the aid of ImageJ software. The results were evaluated by Student's t-test and correlated by the Pearson method. The data obtained by ultrasonography proved reliable, given the high correlations (0.78–0.98) between estimates made using images collected at those standard points and subsequent evaluation from measurements made directly upon the carcass. The correlations for fillet yield (0.51–0.58) and belly fillet yield (0.27–0.42) were moderate. The area averages and depth averages collected at the three standard points showed high correlations with fillet yield (0.58–0.54) and sirloin fillet yield (0.56–0.60). We concluded that the use of ultrasonography in collection of meat-yield phenotypes of economic interest is an effective method for use in direct selection of broodstock candidates in selective breeding programs for Nile tilapia. [ABSTRACT FROM AUTHOR]

The present study was carried out with the objective of determining the requirements for digestible lysine in Nile tilapia during the 500 to 600 g live weight stage. Isocaloric and isonitrogenous diets were tested with increasing amounts of digestible lysine. L-lysine HCl (78%) were used to replace glutamic acid at increasing levels, resulting in treatments of 9.3, 12.3, 15.3, 18.3 and 21.3 g kg-1 of digestible lysine. Three hundred Nile tilapias with an average weight of 519 ± 27.23 g were used and distributed among 25 tanks. The physical and chemical parameters of the water were pH, dissolved oxygen, salinity, conductivity and temperature. The mortality rate was registered daily. Two slaughters were performed at 28 and 50 days after the beginning of the experiment. It was estimated that an amount of 13.1 g kg-1 of digestible lysine was ideal for obtaining higher WG. Fish slaughtered after 50 days, the digestible lysine requirements were determined to be 14.5 g kg-1 for the lowest carcass humidity and 14.6 g kg-1 for the greatest carcass ethereal extract. Nile tilapias with live weight between 500 and 600 grams require 13.1 g kg-1 of digestible lysine in the diet for greater WG (90.53 g) and better FCR (2.55).

In the present work, we studied ten new productive traits in meagre (Argyrosomus regius), comprising three related to the carcass (cNiT) and seven related to morphometric (mNiT) characteristics. We harnessed non-invasive technology (NiT) by means of the IMAFISH_ML software. This tool’s potential was leveraged on an industrial scale, encompassing the evaluation of 612 fish from two distinct rearing systems (marine cages and indoor tanks) at the time of harvest. Each fish underwent digital photography for morphometric measurements, manual weighing, and was manually eviscerated and filleted to calculate the carcass and fillet yield. Subsequently, the principal genetic parameters were estimated. The heritabilities for the growth traits were moderate (0.34 and 0.39 for TL and BW), whilst those for the cNiT traits ranged from medium to low (0.32–0.27). For the mNiT, they demonstrated a medium to low range (0.15–0.37), whereas the carcass and fillet yield heritabilities were considered to be medium to high (0.32 and 0.31). Most of the genetic correlations between the growth, NiT, and yield traits were not estimated accurately due to the limited data. As was expected, we observed predominantly high and positive correlations between the growth and mNiT. A genetic correlation to highlight was the fillet yield with the fish maximum height (0.87 ± 0.23) and with the head height (0.87 ± 0.24). This suggests that indirect selection using NiT could improve the growth and yield traits. Employing a multi-trait selection approach enables us to capture a broader spectrum of genetic variability and to potentially identify individuals with superior genetic potential. The use of image analysis software ensures objective and precise measurements, thereby reducing the potential for human error or bias during the selection process. Further studies should be carried out to improve the accuracy of the estimates, especially those of the genetic correlations.

Simple Summary: The ability to obtain in vivo information on characteristics related to fish composition is necessary for aquaculture. In addition, there is growing interest in production traits, such as growth, feed efficiency or fillet weight, but it remains difficult to precisely record in vivo individual fish traits that report to these production traits, which can increase edible fish meat production and decrease the environmental impact. In the present study, we performed an ultrasound approach for the in vivo prediction of fillet volume of the Senegalese sole (Solea senegalensis), a species considered a promising flatfish species for marine fish farming. The results show that models based on ultrasound fillet volume measurements explain above 95% of the variation observed in fillet volume. However, for fillet yield estimation, the results were modest. Therefore, further studies are necessary to better understand the potential of the ultrasound approach to this trait. Nevertheless, this work allows us to conclude that the approach with ultrasound is promising for measuring in vivo fish composition traits. Senegalese sole (Solea senegalensis) has been considered a promising new flatfish species for Mediterranean marine fish farming. Accurate prediction of fillet traits in live animals may allow for more efficient control of muscle deposition in fish. In this sense, this study was undertaken to develop a non-invasive method to predict in vivo fish fillet volume and yield using real-time ultrasonography (RTU). The trial was conducted with 44 market weight Senegalese sole (298.54 ± 87.30 g). Fish were scanned with an Aloka SSD 500V with a 7.5 MHz probe. Ten RTU cross-sectional images were taken from the operculum to the caudal fin at regular intervals. These images were analyzed using Fiji software. These data were then used to estimate the partial volumes of the fillet. Actual fillet volume was determined using Archimedes' principle. Simple and stepwise multiple regression analyses were then used to develop prediction models of fillet volume and yield. The most cranial RTU sections of the fish fillet were the best single predictors of both fillet volume and fillet yield and were the ones included in the best stepwise models. The best RTU slice area explained 82% of the variation observed in fillet volume, but the other RTU slice areas used as predictors of fillet volume showed poor to moderate accuracy (0.035 ≤ R2 ≤ 0.615). Single RTU partial volumes showed poor to very high accuracy (0.395 ≤ R2 ≤ 0.970) as predictors of fillet volume. The best stepwise model based on the RTU slice areas included three independent variables and explained 88.3% of the observed variation. The best stepwise models based on RTU partial volumes (single volumes and/or combinations of single volumes) explained about 97% of the variation observed in fillet volume. Two RTU volume traits, V1–5 + V6–9, and V1+()+9, showed to be practically direct predictors of the actual fillet volume, explaining, respectively, 97% and 96% of the variation observed in the actual fillet volume. The fillet yields show lower correlations with slice areas (r between 0.044 and 0.601) than with volumes (r between 0.288 and 0.637). While further studies are clearly necessary to better understand the potential of RTU for the estimation of fillet yield in fish in general and Senegalese sole in particular, the present results showed that RTU traits can be very good predictors of Senegalese sole's fillet volume, either used in regression models or as direct predictors. [ABSTRACT FROM AUTHOR]

The study was carried out with six-summer-old male Russian sturgeon raised in an industrial cage farm. At the end of the vegetation season, two groups of fish were formed: with lower (3010.80 ± 72.96 g) and higher (4910.0 ± 100.30 g) live weight. It was found that fish of both weight groups were characterized by high slaughter yield and a small proportion of non-edible parts. As the total weight of fish increased, the relative share of the head, gills, pyloric gland and bone plates decreased significantly. Fish with lower live weight had significantly higher slaughter and edible yields and no significant difference was found between the groups concerning the yield for the processing industry. With the increase in live weight, the relative share of meat in the whole body and in the carcass decreased, but the differences between the groups were insignificant. According to all the exterior characteristics, a significant difference was found between the groups in favour of fish with higher total weight. However, in the case of exterior indices, a significant difference was found only in the high-backed index in favour of the smaller fish. In the interior indices, a significant difference in favour of the larger fish was found for viscerosomatic index (38.4%) and gonadosomatic index (91.2%). For other interior indices, with the exception of heartsomatic index, higher values were also reported in fish of higher live weight, but the differences were insignificant. [ABSTRACT FROM AUTHOR]

The increase in fish and seafood consumption observed in recent years is a consequence of the growing consumers' awareness of proper nutrition. One of the possibilities to provide fish-friendly, qualitatively attractive (both in terms of nutrition and sensory quality) raw fish materials is the production of hybrids, which would improve production rates without compromising their meat quality. This study compares the carcass and fillet yields of Clarias gariepinus (C) and heteroclarias C. gariepinus × Heterobranchus longifilis (H), and the nutritional (chemical composition, fat quality) and culinary quality (structure, texture, color, cooking loss, sensory characteristics) of their meat. Significantly (p ≤ 0.05) higher carcass and fillet yield was shown for H, whose fillets had comparable sensory quality and proximal composition to C. The meat of H can be an attractive raw material for more demanding groups of consumers—for children and adolescents (due to the less intense fish tastiness), as well as for older people who have problems with chewing and digesting food (due to lower sensory chewiness and perception of connective tissue). [ABSTRACT FROM AUTHOR]

Commercial feeds, encoded by letters A, B, and C, with crude protein between 49.1% and 52.9% and crude fat between 13.0% and 22.2% produced especially for percids were fed to European perch (Perca fluviatilis) with an initial body weight of 91.9 g in a 106-day trial during grow-out in a recirculating aquaculture system. A feed manufactured and declared for sturgeon and sea bass farming but traditionally used for percids served as control diet (feed D). In comparison to the best performing percid feed, the sturgeon/sea bass feed D showed similar results. Feed A showed best results in terms of weight gain (14.6 kg), food conversion ratio (1.65), specific growth rate (0.74%/day) and second best survival rates, (98.1%). Differences in slaughter yield were significant only regarding the viscerosomatic index, whereas fillet yield, condition factor (K), hepatosomatic index, and proximate composition of whole body and fillet were comparable for all diets. In conclusion, three different commercial feeds specialized for percid production revealed significantly different production success in a recirculating aquaculture system. On the other hand, a commercial feed with similar composition sold for sturgeon/sea bass also achieved acceptable results. [ABSTRACT FROM AUTHOR]

This study compared three different fish species, striped catfish (Pangasius hypophthalmus), African catfish (Clarias gariepinus) and snakehead (Channa striata), regarding the effect of dietary macronutrient composition on: 1. the fillet yield and the fillet chemical composition; 2. the location of fat deposition within the body (fillet, liver, viscera or rest fraction). The selected species were studied for the development of net energy formulas, in three different studies. The design of these studies and especially the diet formulation were similar. Diets were formulated according to a 2 × 2 factorial design: with or without extra carbohydrates supplementation; and with or without extra fat supplementation. Fillet yield of striped catfish (P. hypophthalmus), African catfish (C. gariepinus) and snakehead (C. striata) was not affected by the dietary macronutrient composition. Fillet fat and protein contents were changed by the dietary macronutrient composition. In all compartments (liver, viscera, fillet and the rest fraction), both dietary fat and dietary carbohydrates levels increased the fat content. The response to dietary carbohydrates in snakehead, a lowering of fillet fat content, is opposite to the response in both catfish species. The distribution of the total amount of body fat over the different compartments, was not influenced by dietary carbohydrates level, but did depend on dietary fat level. Dietary fat supplementation led to relatively more fat in viscera and fillet but less fat was stored in the rest fraction. In striped catfish (P. hypophthalmus), African catfish (C. gariepinus) and snakehead (C. striata), most of the body fat is stored in the rest fraction (head, skin, subcutaneous fat, scales, bones and air bladders).

Senegalese sole (Solea senegalensis) has been considered a promising new flatfish species for Mediterranean marine fish farming. Accurate prediction of fillet traits in live animals may allow for more efficient control of muscle deposition in fish. In this sense, this study was undertaken to develop a non-invasive method to predict in vivo fish fillet volume and yield using real-time ultrasonography (RTU). The trial was conducted with 44 market weight Senegalese sole (298.54 ± 87.30 g). Fish were scanned with an Aloka SSD 500V with a 7.5 MHz probe. Ten RTU cross-sectional images were taken from the operculum to the caudal fin at regular intervals. These images were analyzed using Fiji software. These data were then used to estimate the partial volumes of the fillet. Actual fillet volume was determined using Archimedes’ principle. Simple and stepwise multiple regression analyses were then used to develop prediction models of fillet volume and yield. The most cranial RTU sections of the fish fillet were the best single predictors of both fillet volume and fillet yield and were the ones included in the best stepwise models. The best RTU slice area explained 82% of the variation observed in fillet volume, but the other RTU slice areas used as predictors of fillet volume showed poor to moderate accuracy (0.035 ≤ R2 ≤ 0.615). Single RTU partial volumes showed poor to very high accuracy (0.395 ≤ R2 ≤ 0.970) as predictors of fillet volume. The best stepwise model based on the RTU slice areas included three independent variables and explained 88.3% of the observed variation. The best stepwise models based on RTU partial volumes (single volumes and/or combinations of single volumes) explained about 97% of the variation observed in fillet volume. Two RTU volume traits, V1–5 + V6–9, and V1+()+9, showed to be practically direct predictors of the actual fillet volume, explaining, respectively, 97% and 96% of the variation observed in the actual fillet volume. The fillet yields show lower correlations with slice areas (r between 0.044 and 0.601) than with volumes (r between 0.288 and 0.637). While further studies are clearly necessary to better understand the potential of RTU for the estimation of fillet yield in fish in general and Senegalese sole in particular, the present results showed that RTU traits can be very good predictors of Senegalese sole’s fillet volume, either used in regression models or as direct predictors.

The increase in fish and seafood consumption observed in recent years is a consequence of the growing consumers’ awareness of proper nutrition. One of the possibilities to provide fish-friendly, qualitatively attractive (both in terms of nutrition and sensory quality) raw fish materials is the production of hybrids, which would improve production rates without compromising their meat quality. This study compares the carcass and fillet yields of Clarias gariepinus (C) and heteroclarias C. gariepinus × Heterobranchus longifilis (H), and the nutritional (chemical composition, fat quality) and culinary quality (structure, texture, color, cooking loss, sensory characteristics) of their meat. Significantly (p ≤ 0.05) higher carcass and fillet yield was shown for H, whose fillets had comparable sensory quality and proximal composition to C. The meat of H can be an attractive raw material for more demanding groups of consumers—for children and adolescents (due to the less intense fish tastiness), as well as for older people who have problems with chewing and digesting food (due to lower sensory chewiness and perception of connective tissue).

This study aimed to evaluate the effects of lysine and histidine supplementation on growth performance, gene expression, blood parameters and quality of the fillet in Nile tilapia, Oreochromis niloticus (n = 192; 136.14 ± 2.32 g). Fish were distributed into four groups and fed a control diet without lysine and histidine supplementation (CON), supplemented with lysine (LYS), histidine (HIS) or lysine and histidine (LYS + HIS) and fed until apparent satiety for 90 days. Growth performance increased significantly in fish fed diet LYS + HIS (p <.05). The fillet body weight gain and fillet yield increased by 26.61% and 2.74% unit, respectively, compared to fish fed CON diet (p <.001). Compared to the control group, fish fed diets showed decreased whole‐body lipid and plasmatic triglycerides coupled to increased mRNA levels of MyoD and myogenin in the skeletal muscle and higher texture attributes of fillets (p <.05). There was a substantial negative correlation between body lipids and hardness of fillets. Overall, the combined supplementation of lysine and histidine optimizes growth performance, expression of muscle growth‐related genes and flesh quality attributes in grow‐out Nile tilapia. [ABSTRACT FROM AUTHOR]

The study was carried out with a four-summer-old male Siberian sturgeon, reared in net cages, installed in a large warm reservoir in Bulgaria. Two groups of fish were formed for the purpose of the analysis made at the end of the vegetation period – with lower (2823.0 ± 126.04 g) and higher (4273.2 ± 110.29 g) live weight. Fish of the first group had significantly lower weight of the carcass, fillet, total insides, gonads, liver, fins and tail, head without gills, gills, swim bladder and chord, compared to fish with higher live weight. The two groups did not differ significantly in the weight of heart, spleen and bone plates. In the frames of the experiment, the eviscerated weight and the relative share of carcass in the total body weight was 86.40-86.86% and 57.07-61.52%, respectively. The relative share of the whole fillet with skin in the body and in the carcass was 45.61-50.75% and 78.37-82.54%, respectively. All the parameters characterizing the slaughter value showed better results in fish with higher live weight, but the difference between the groups was significant only in the relative share of the fillet in the carcass (4.16%, p<0.001). All the indices of fish condition were higher in the group with higher live weight, the difference being significant in the condition index IC (p<0.01) and in the modified Fulton’s coefficient ICR (p<0.05). Referring to the interior indices, no clear dependencies were established related to fish live weight. The viscerosomatic and cardiosomatic indices were higher in the smaller fishes, and the hepatosomatic, spleen-somatic and gonadosomatic indices – in the heavier representatives, the difference being significant only in the latter index (p<0.05). [ABSTRACT FROM AUTHOR]

Abstract The purpose of this study was to develop and validate prediction equations for fillet traits in Asian sea bass. Ninety-day old fish (average weight = 9.48 ± 0.35 g; length = 8.78 ± 0.6 cm) from four hatchery stocks (Chachoengsao, Chon Buri, Chumphon, and Samut Songkram) were raised in earthen ponds. After 300 days, weight and body measurement data of live fish (n = 400) were collected. Mean individual weight was greatest for the Chacheongsao stock (1166.32 ± 23.42 g) and was similar for the other stocks, ranging from 982.96 ± 25.07 to 997.44 ± 24.71 g. Fillet percentage varied slightly from 47.33 to 49.88%. Positive high correlations were observed for weight and body measurements with fillet weight, whereas there were significant but weak correlations for body measurements with fillet yield. Prediction equations developed from body weight using simple linear regression models yielded R 2 values of 0.97–0.98 for fillet weight for each stock. Correlations between values predicted from the body weight models and actual values were 0.98–0.99 for fillet weight. Stepwise regression was performed to develop prediction models for fillet yield from body measurements. The best fillet yield prediction models identified length and an additional 2–3 measurement as potential predictors depending on the population. Prediction biases were close to zero despite low to moderate (r values of 0.20–0.51) degrees of predictive power of the models. However, prediction models for fillet yield should be further developed to increase predictability and be applicable to new data.

Fillet yield, the proportion of edible fillet relative to body weight, is a major trait to improve in fish sold processed, as it has a direct impact on profitability and can simultaneously decrease the environmental impact of producing a given amount of fillet. However, it is difficult to improve by selective breeding, because it cannot be measured on live breeding candidates, its phenotypic variation is low, and, as a ratio, it is not normally distributed and a same change in fillet yield can be the result of different changes in fillet weight and body weight. Residual headless gutted carcass weight (rHGCW) is heritable and highly genetically correlated to Fillet% in rainbow trout, and can be predicted by the ratio of abdominal wall thickness to depth of the peritoneal cavity (E8/E23), measured on live fish by ultrasound tomography. We selected broodstock based on rHGCW, measured on sibs of the selection candidates, on ultrasound measurements (E8/E23) measured on the selection candidates, or a combination of both. Seven broodstock groups were selected: fish with 15% highest (rHGCW+) or lowest (rHGCW−) EBV for rHGCW, with 15% highest (E8/E23+) or lowest (E8/E23−) EBV for E8/E23, with both rHGCW+ and E8/E23+ (Both+) or rHGCW− and E8/E23− (Both−), or with close to zero EBVs for both traits (Mid). Seven corresponding groups of offspring were produced and reared communally. At harvest size (1.5 kg mean weight), 1,561 trout were slaughtered, measured for the traits of interest, and pedigreed with DNA fingerprinting. Offspring from groups Both+, rHGCW+ and E8/E23+ had a higher EBV for rHGCW than the control group, while down-selected groups had a lower EBV. Looking at the phenotypic mean for Fillet% (correlated response), up-selected fish had more fillet than down-selected fish. The highest difference was between Both+ (69.36%) and Both− (68.20%), a 1.16% units difference in fillet percentage. The change in Fillet% was explained by an opposite change in Viscera%, while Head% remained stable. Selection using sib information on rHGCW was on average more efficient than selection using the candidates’ own E8/E23 phenotypes, and downward selection (decreasing Fillet%) was more efficient than upward selection.

Fillet yield, the proportion of edible fillet relative to body weight, is a major trait to improve in fish sold processed, as it has a direct impact on profitability and can simultaneously decrease the environmental impact of producing a given amount of fillet. However, it is difficult to improve by selective breeding, because it cannot be measured on live breeding candidates, its phenotypic variation is low, and, as a ratio, it is not normally distributed and a same change in fillet yield can be the result of different changes in fillet weight and body weight. Residual headless gutted carcass weight (rHGCW) is heritable and highly genetically correlated to Fillet% in rainbow trout, and can be predicted by the ratio of abdominal wall thickness to depth of the peritoneal cavity (E8/E23), measured on live fish by ultrasound tomography. We selected broodstock based on rHGCW, measured on sibs of the selection candidates, on ultrasound measurements (E8/E23) measured on the selection candidates, or a combination of both. Seven broodstock groups were selected: fish with 15% highest (rHGCW+) or lowest (rHGCW−) EBV for rHGCW, with 15% highest (E8/E23+) or lowest (E8/E23−) EBV for E8/E23, with both rHGCW+ and E8/E23+ (Both+) or rHGCW− and E8/E23− (Both−), or with close to zero EBVs for both traits (Mid). Seven corresponding groups of offspring were produced and reared communally. At harvest size (1.5 kg mean weight), 1,561 trout were slaughtered, measured for the traits of interest, and pedigreed with DNA fingerprinting. Offspring from groups Both+, rHGCW+ and E8/E23+ had a higher EBV for rHGCW than the control group, while down-selected groups had a lower EBV. Looking at the phenotypic mean for Fillet% (correlated response), up-selected fish had more fillet than down-selected fish. The highest difference was between Both+ (69.36%) and Both− (68.20%), a 1.16% units difference in fillet percentage. The change in Fillet% was explained by an opposite change in Viscera%, while Head% remained stable. Selection using sib information on rHGCW was on average more efficient than selection using the candidates' own E8/E23 phenotypes, and downward selection (decreasing Fillet%) was more efficient than upward selection. [ABSTRACT FROM AUTHOR]

Detection of coding/functional SNPs that change the biological function of a gene may lead to identification of putative causative alleles within QTL regions and discovery of genetic markers with large effects on phenotypes. This study has two-fold objectives, first to develop, and validate a 50K transcribed gene SNP-chip using RNA-Seq data. To achieve this objective, two bioinformatics pipelines, GATK and SAMtools, were used to identify ~21K transcribed SNPs with allelic imbalances associated with important aquaculture production traits including body weight, muscle yield, muscle fat content, shear force, and whiteness in addition to resistance/susceptibility to bacterial cold-water disease (BCWD). SNPs ere identified from pooled RNA-Seq data collected from ~620 fish, representing 98 families from growth- and 54 families from BCWD-selected lines with divergent phenotypes. In addition, ~29K transcribed SNPs without allelic-imbalances were strategically added to build a 50K Affymetrix SNP-chip. SNPs selected included two SNPs per gene from 14K genes and ~5K non-synonymous SNPs. The SNP-chip was used to genotype 1728 fish. The average SNP calling-rate for samples passing quality control (QC; 1,641 fish) was ≥ 98.5%. The second objective of this study was to test the feasibility of using the new SNP-chip in GWA (Genome-wide association) analysis to identify QTL explaining muscle yield variance. GWA study on 878 fish (representing 197 families from 2 consecutive generations) with muscle yield phenotypes and genotyped for 35K polymorphic markers (passing QC) identified several QTL regions explaining together up to 28.40% of the additive genetic variance for muscle yield in this rainbow trout population. The most significant QTLs were on chromosomes 14 and 16 with 12.71 and 10.49% of the genetic variance, respectively. Many of the annotated genes in the QTL regions were previously reported as important regulators of muscle development and cell signaling. No major QTLs were identified in a previous GWA study using a 57K genomic SNP chip on the same fish population. These results indicate improved detection power of the transcribed gene SNP-chip in the target trait and population, allowing identification of large-effect QTLs for important traits in rainbow trout.

The influence of weight (W) category of the rainbow trout on processing yield and chemical composition of the entire eviscerated fish and fish fillet was analyzed. A completely randomized design was employed for processing variables (W1 = 300 to 370 g and W2 = 371 to 440) coupled to a 2 x 2 factorial scheme for the chemical composition (W1 and W2 and forms of presentation: fillet and whole eviscerated fish). W1 showed higher yield for entire eviscerated fish (83.00%) and head (13.27%), but a lower yield for the viscera (17.00%), when compared to W2. We did not affect abdominal muscle yield, fillet with or without skin, skin percentage and residues. There were significant differences between W for moisture (W1 = 72.30% and W2 = 71.15%) and lipids (CP1 = 7.96% and CP2 = 9.04%) rates. Fillet moisture contents (73.74%) and crude protein (19.05%) were higher (p < 0.01) than for entire eviscerated fish (69.71% and 17.81%, respectively). Ash (2.15%) and lipid (10.48%) rates were higher (p < 0.01) for entire fish when compared to those of fillets (1.16% and 6.52%, respectively). The slaughter of fish weighing between 300 and 370 g and their fillets are more adequate for the market.

Detection of coding/functional SNPs that change the biological function of a gene may lead to identification of putative causative alleles within QTL regions and discovery of genetic markers with large effects on phenotypes. This study has two-fold objectives, first to develop, and validate a 50K transcribed gene SNP-chip using RNA-Seq data. To achieve this objective, two bioinformatics pipelines, GATK and SAMtools, were used to identify ~21K transcribed SNPs with allelic imbalances associated with important aquaculture production traits including body weight, muscle yield, muscle fat content, shear force, and whiteness in addition to resistance/susceptibility to bacterial cold-water disease (BCWD). SNPs ere identified from pooled RNA-Seq data collected from ~620 fish, representing 98 families from growth- and 54 families from BCWD-selected lines with divergent phenotypes. In addition, ~29K transcribed SNPs without allelic-imbalances were strategically added to build a 50K Affymetrix SNP-chip. SNPs selected included two SNPs per gene from 14K genes and ~5K non-synonymous SNPs. The SNP-chip was used to genotype 1728 fish. The average SNP calling-rate for samples passing quality control (QC; 1,641 fish) was ≥ 98.5%. The second objective of this study was to test the feasibility of using the new SNP-chip in GWA (Genome-wide association) analysis to identify QTL explaining muscle yield variance. GWA study on 878 fish (representing 197 families from 2 consecutive generations) with muscle yield phenotypes and genotyped for 35K polymorphic markers (passing QC) identified several QTL regions explaining together up to 28.40% of the additive genetic variance for muscle yield in this rainbow trout population. The most significant QTLs were on chromosomes 14 and 16 with 12.71 and 10.49% of the genetic variance, respectively. Many of the annotated genes in the QTL regions were previously reported as important regulators of muscle development and cell signaling. No major QTLs were identified in a previous GWA study using a 57K genomic SNP chip on the same fish population. These results indicate improved detection power of the transcribed gene SNP-chip in the target trait and population, allowing identification of large-effect QTLs for important traits in rainbow trout. [ABSTRACT FROM AUTHOR]

The purpose of this study was to develop and validate prediction equations for fillet traits in Asian sea bass. Ninety-day old fish (average weight = 9.48 ± 0.35 g; length = 8.78 ± 0.6 cm) from four hatchery stocks (Chachoengsao, Chon Buri, Chumphon, and Samut Songkram) were raised in earthen ponds. After 300 days, weight and body measurement data of live fish (n = 400) were collected. Mean individual weight was greatest for the Chacheongsao stock (1166.32 ± 23.42 g) and was similar for the other stocks, ranging from 982.96 ± 25.07 to 997.44 ± 24.71 g. Fillet percentage varied slightly from 47.33 to 49.88%. Positive high correlations were observed for weight and body measurements with fillet weight, whereas there were significant but weak correlations for body measurements with fillet yield. Prediction equations developed from body weight using simple linear regression models yielded R2 values of 0.97-0.98 for fillet weight for each stock. Correlations between values predicted from the body weight models and actual values were 0.98-0.99 for fillet weight. Stepwise regression was performed to develop prediction models for fillet yield from body measurements. The best fillet yield prediction models identified length and an additional 2-3 measurement as potential predictors depending on the population. Prediction biases were close to zero despite low to moderate (r values of 0.20-0.51) degrees of predictive power of the models. However, prediction models for fillet yield should be further developed to increase predictability and be applicable to new data. [ABSTRACT FROM AUTHOR]

Different methods in use for cold smoking of salmon affect product yield and quality. The combinations of filleting time (pre or post), salting methods (dry or injection), salting targets (2.5 or 4%) and smoking temperatures (15 or 25 °C) were studied during 6 weeks of 4 °C cold storage. Salting method had the greatest influence on flesh quality. Injection salting led to 15% higher fillet yield, moderate to strong gaping score, softer texture, and paler fish compared with dry salting. Pre-rigor filleting reduced fillet gaping from a moderate to minor score, but only in dry salted fillets. Smoking at 15 °C reduced yield by 0.5% in injected salted fish, compared with 25 °C. The combination of pre-rigor filleting, dry salting and 15 °C smoking temperature gave the lowest gaping incidence and highest shear force and flesh colour. Liquid loss increased by 240% and the L-value by 6.5 units during 6 weeks cold storage, whereas the other quality parameters measured showed only small changes during the storage period. [ABSTRACT FROM AUTHOR]

Improvement of fillet traits and flesh quality attributes are of great interest in farmed tilapia and other aquaculture species. The main objective of this study was to estimate genetic parameters for fillet traits (fillet weight and fillet yield) and the fat content of fillets from 1136 males combined with 2585 data records on growth traits (body weight at 290 days, weight at slaughter, and daily weight gain) of 1485 males and 1100 females from a third generation of the Aquaamerica tilapia strain. Different models were tested for each trait, and the best models were used to estimate genetic parameters for the fat content, fillet, and growth traits. Genetic and phenotypic correlations were estimated using two-trait animal models. The heritability estimates were moderate for the fat content of fillets and fillet yield (0.2-0.32) and slightly higher for body weight at slaughter (0.41). The genetic correlation between fillet yield and fat was significant (0.6), but the genetic correlations were not significant between body weight and fillet yield, body weight and fat content, daily weight gain and fillet yield, and daily weight gain and fat content (− 0.032, − 0.1, − 0.09, and − 0.4, respectively). Based on the genetic correlation estimates, it is unlikely that changes in fillet yield and fat content will occur when using growth performance as a selection criterion, but indirect changes may be expected in fat content if selecting for higher fillet yield. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of ratio of dietary digestible protein (DP) to digestible energy (DE) on growth performance, fillet chemical composition and haematological profile of Nile tilapia subjected to transport-induced stress at the final rearing stage (450 to 800 g) under commercial conditions. The trial was conducted using a 5 × 2 factorial layout (DP: 200, 230, 260, 290 and 320 g kg−1) and (DE: 12.6 and 13.8 MJ kg−1). Energy levels did not influence any analysed parameters in this research. Final weight and biomass gain were increased up to the ratio of 269 and 270 g PD kg−1, respectively, and feed conversion ratio was reduced down to a 275 g DP kg−1. Protein efficiency ratio linearly decreased from 200 g DP kg−1 diet to 320 g DP kg−1. There was no statistical difference in fillet chemical composition. Red blood cell count (RBC), haemoglobin (Hb), mean corpuscular volume (MCV) and mean corpuscular haemoglobin concentration (MCHC) were different before and after transport-induced stress. Leucocyte differentiation after transport-induced stress revealed lymphocytopenia and neutrophilia. We conclude that for tilapia weighing 450-800 g reared under commercially intensive conditions, a diet with 270 g DP kg−1 and 12.6 MJ DE kg−1 (21.43 g DP MJ−1 DE) can improve the growth performance and ensure the fish health. [ABSTRACT FROM AUTHOR]

This trial was conducted to determine the dietary digestible methionine + cystine requirement of Nile tilapia (550 to 700 g) based on the ideal protein concept. Six hundred fish were distributed in a completely randomized design with five treatments and four replicates, with 30 fish per experimental unit. The fish were fed diets containing approximately 262 g of digestible protein/kg, 3,040 kcal of digestible energy/kg and 7.90, 9.40, 10.90, 12.40 or 13.90 g of methionine + cystine/kg. The fish were hand-fed three times a day until apparent satiation for 30 days. No effects of dietary methionine + cystine on feed conversion ratio, daily protein deposition, whole body moisture, fillet moisture, crude protein, ether extract and ash, plasmatic HDL and LDL cholesterol were observed. Dietary methionine resulted in a linear increase in whole body protein and linear reduction in lipid deposition rate, hepatosomatic index, whole body ether extract and ash, plasmatic total cholesterol, plasmatic total lipids and plasmatic triglycerides. According to the Linear Response Plateau, the daily weight gain and fillet yield increased up to a level of 9.00 and 9.90 g methionine + cystine/kg of diet, respectively. The digestible methionine + cystine requirement of Nile tilapia is 9.00 g/kg for weight gain and 9.90 g/kg for fillet yield, corresponding to methionine + cystine:lysine ratios of 0.60 and 0.66, respectively.

Fillet yield (FY, %) is an economically-important trait in rainbow trout aquaculture that affects production efficiency. Despite that, FY has received little attention in breeding programs because it is difficult to measure on a large number of fish and cannot be directly measured on breeding candidates. The recent development of a high-density SNP array for rainbow trout has provided the needed tool for studying the underlying genetic architecture of this trait. A genome-wide association study (GWAS) was conducted for FY, body weight at 10 (BW10) and 13 (BW13) months post-hatching, head-off carcass weight (CAR), and fillet weight (FW) in a pedigreed rainbow trout population selectively bred for improved growth performance. The GWAS analysis was performed using the weighted single-step GBLUP method (wssGWAS). Phenotypic records of 1,447 fish (1.5 kg at harvest) from 299 full-sib families in three successive generations, of which 875 fish from 196 full-sib families were genotyped, were used in the GWAS analysis. A total of 38,107 polymorphic SNPs were analyzed in a univariate model with hatch year and harvest group as fixed effects, harvest weight as a continuous covariate, and animal and common environment as random effects. A new linkage map was developed to create windows of 20 adjacent SNPs for use in the GWAS. The two windows with largest effect for FY and FW were located on chromosome Omy9 and explained only 1.0 to 1.5% of genetic variance, thus suggesting a polygenic architecture affected by multiple loci with small effects in this population. One window on Omy5 explained 1.4% and 1.0% of the genetic variance for BW10 and BW13, respectively. Three windows located on Omy27, Omy17 and Omy9 (same window detected for FY) explained 1.7%, 1.7%, and 1.0%, respectively, of genetic variance for CAR. Among the detected 100 SNPs, 55% were located directly in genes (intron and exons). Nucleotide sequences of intragenic SNPs were blasted to the Mus musculus genome to create a putative gene network. The network suggests that differences in the ability to maintain a proliferative and renewable population of myogenic precursor cells may affect variation in growth and fillet yield in rainbow trout.

Com o objetivo de avaliar os rendimentos do processamento de linhagens de tilápias em função dos pesos de abate, um experimento foi conduzido no setor de piscicultura da Universidade Federal de Lavras, M.G. - Brasil. Foram utilizados 93 peixes da linhagem Chitralada e 78 da Supreme, pesando entre 150 e 790 g. Os peixes foram cultivados em dois tanques de alvenaria de 40 m², sendo alimentados com ração comercial fornecida de acordo com a biomassa e a temperatura da água. A temperatura e o oxigênio da água foram tomados diariamente, no início do dia e no final da tarde, e o pH aferido semanalmente. Com o crescimento dos animais, amostras aleatórias foram tomadas. Nas amostragens, os peixes foram abatidos após terem passado por um jejum de 24 horas e insensibilização por choque térmico. Em seguida, foram pesados e dissecados. A análise de regressão indicou que em pesos mais elevados, a linhagem Chitralada apresenta maior porcentagem de cabeça e rendimento de pele. A linhagem Supreme apresentou maior peso de carcaça, filé e resíduos, sendo mais expressivos em pesos superiores a 500 g e menor valor à maturidade para a % de vísceras. Conclui-se que as duas linhagens possuem crescimento das partes componentes proporcional ao aumento do peso corporal, e este aumento não altera o rendimento desses constituintes. A linhagem Supreme apresentou maiores rendimentos de carcaça e filé do que a Chitralada, sendo a mais indicada para a produção e comercialização de filés mais pesados.With the objective of evaluating the yield processing of tilapia strains in function of body weight, an experiment was carried out at the Fish Culture of the Animal Sciences Department, Federal University of Lavras, M.G. - Brazil. A total 93 fish of the Chitralada strain and 78 of the Supreme strain, weighting between 150 and 790 g were used. The fish were cultivated in two tanks of 40 m², fed with commercial ration supplied according to the biomass and water temperature. The water temperature and oxygen were evaluated every day, at the early morning and at the late afternoon, and the pH checked weekly. During the fish growth, random samples were taken. After 24 hours of fasting, the fish were insensibilized (thermal shock), slaughtered (anoxia), weighted and dissected. The regression analysis showed that in higher weight, the Chitralada strain presented higher head percentage and skin yield. The Supreme strain presented higher carcass, fillet and residue weights, being more expressive in body weights superior to 500 g and smaller limiting value for the percentage of viscera. It was concluded that the two strains have growth of body parts proportional to the increase of the body weight, and this increase does not modify the parts yield. The Supreme strain showed more carcass and fillet yield than Chitralada, and is should be indicated for production and commercialization of heavier fillet.

Fillet yield (FY, %) is an economically-important trait in rainbow trout aquaculture that affects production efficiency. Despite that, FY has received little attention in breeding programs because it is difficult to measure on a large number of fish and cannot be directly measured on breeding candidates. The recent development of a high-density SNP array for rainbow trout has provided the needed tool for studying the underlying genetic architecture of this trait. A genome-wide association study (GWAS) was conducted for FY, body weight at 10 (BW10) and 13 (BW13) months post-hatching, head-off carcass weight (CAR), and fillet weight (FW) in a pedigreed rainbow trout population selectively bred for improved growth performance. The GWAS analysis was performed using the weighted single-step GBLUP method (wssGWAS). Phenotypic records of 1447 fish (1.5 kg at harvest) from 299 full-sib families in three successive generations, of which 875 fish from 196 full-sib families were genotyped, were used in the GWAS analysis. A total of 38,107 polymorphic SNPs were analyzed in a univariate model with hatch year and harvest group as fixed effects, harvest weight as a continuous covariate, and animal and common environment as random effects. A new linkage map was developed to create windows of 20 adjacent SNPs for use in the GWAS. The two windows with largest effect for FY and FW were located on chromosome Omy9 and explained only 1.0-1.5% of genetic variance, thus suggesting a polygenic architecture affected by multiple loci with small effects in this population. One window on Omy5 explained 1.4 and 1.0% of the genetic variance for BW10 and BW13, respectively. Three windows located on Omy27, Omy17, and Omy9 (same window detected for FY) explained 1.7, 1.7, and 1.0%, respectively, of genetic variance for CAR. Among the detected 100 SNPs, 55% were located directly in genes (intron and exons). Nucleotide sequences of intragenic SNPs were blasted to the Mus musculus genome to create a putative gene network. The network suggests that differences in the ability to maintain a proliferative and renewable population of myogenic precursor cells may affect variation in growth and fillet yield in rainbow trout. [ABSTRACT FROM AUTHOR]

The contribution of sex steroids to nutrient partitioning and energy balance during gonad development was studied in rainbow trout. Specifically, 19-mo old triploid (3N) female rainbow trout were fed treatment diets supplemented with estradiol-17β (E2), testosterone (T), or dihydrotestosterone at 30-mg steroid/kg diet for a 1-mo period. Growth performance, nutrient partitioning, and expression of genes central to growth and nutrient metabolism were compared with 3N and age-matched diploid (2N) female fish consuming a control diet not supplemented with steroids. Only 2 N fish exhibited active gonad development, with gonad weights increasing from 3.7% to 5.5% of body weight throughout the study, whereas gonad weights in 3N fish remained at 0.03%. Triploid fish consuming dihydrotestosterone exhibited faster specific growth rates than 3N-controls ( P < 0.05). Consumption of E2 in 3N fish reduced fillet growth and caused lower fillet yield compared with all other treatment groups ( P < 0.05). In contrast, viscera fat gain was not affected by steroid consumption ( P > 0.05). Gene transcripts associated with physiological pathways were identified in maturing 2N and E2-treated 3N fish that differed in abundance from 3N-control fish ( P < 0.05). In liver these mechanisms included the growth hormone/insulin-like growth factor (IGF) axis ( igf1 , igf2 ), IGF binding proteins ( igfbp1b1 , igfbp2b1 , igfbp5b1 , igfbp6b1 ), and genes associated with lipid binding and transport ( fabp3 , fabp4 , lpl , cd36 ), fatty acid oxidation ( cpt1a ), and the pparg transcription factor. In muscle, these mechanisms included reductions in myogenic gene expression ( fst , myog ) and the proteolysis-related gene, cathepsin-L, suggesting an E2-induced reduction in the capacity for muscle growth. These findings suggest that increased E2 signaling in the sexually maturing female rainbow trout alters physiological pathways in liver, particularly those related to IGF signaling and lipid metabolism, to partition nutrients away from muscle growth toward support of maturation-related processes. In contrast, the mobilization of viscera lipid stores appear to be mediated less by E2 and more by energy demands associated with gonad development. These findings improve the understanding of how steroids regulate nutrient metabolism to meet the high energy demands associated with gonad development during sexual maturation. [ABSTRACT FROM AUTHOR]

Objetivou-se, com o presente trabalho, avaliar o efeito do peso de abate sobre os rendimentos do processamento do peixe teleósteo piracanjuba (Brycon orbignyanus, Valenciennes, 1849). Inicialmente, alevinos com peso médio de 12 g, oriundos da Estação Experimental da Usina Hidrelétrica de Itutinga, foram estocados e cultivados em um viveiro de terra na Estação de Piscicultura do Departamento de Zootecnia da Universidade Federal de Lavras. Ao final de 18 meses de cultivo, 121 peixes foram insensibilizados, abatidos, pesados e dissecados, para a determinação das porcentagens de cabeça (%CAB), nadadeiras (%NAD), vísceras (%VIS), pele com escamas (%PE), e resíduos da filetação (%RF) e dos rendimentos de carcaça (RCAR) e de filé sem pele (RFSP), em relação ao peso de abate. Para as análises de variância, os dados obtidos foram agrupados em 4 classes de peso (CP1=515 g a 629 g; CP2=630 g a 744 g; CP3=745 g a 859 g; e CP4=860 g a 975 g) e as equações de regressão estimadas em função do peso médio de cada classe. Não foi constatado (P>0,05) efeito de classe de peso sobre RCAR, %NAD e %PE. Por outro lado, observaram-se efeito linear do peso de abate sobre %CAB (PThe objective of this study was to evaluate the effect of body weight on processing yields of a teleost fish piracanjuba (Brycon orbignyanus, Valenciennes, 1849). Firstly, fingerlings were reared in ponds in the Fish Culture of the Animal Sciences Department, Federal University of Lavras, M.G. - Brazil, for 18 months. Then, 121 fishes were insensibilized, slaughtered, weighed and dissected, in order to determine the percentages of head (%CAB), fins (%NAD), visceras (%VIS), skin with scales (%PE), and fillet residues (%RF), and the carcass yield (RCAR) and fillet without skin yield (RFSP), in relation to body weight. For analyses of variances, data were distributed over four weight classes (CP1 = 515 to 629g; CP2 = 630 to 744g; CP3 = 745 to 859g; and CP4 = 860 to 975g) and the regression equations were estimated in function of mean weight of each class. There was no effect (P>0,05) of weight class on RCAR, %NAD and %PE. However, a linear effect of body weight on %CAB (P

Fillet yield, colour, chemical composition and fatty acid composition in the reciprocal hybrid (SSZ) of Siberian sturgeon with its crossbred with green sturgeon were analysed. It was found that fillet yield in relation to the weight of gutted and deheaded carcass did not deviate from the parent forms. SSZ does not keep the salmon-pink colour of tissue, which is typical of the father form. Its tissue contains more (P ≤ 0.01) protein and less (P ≤ 0.01) water than the parental tissue as well as less (P ≤ 0.01) fat than the father's tissue. The percentage of MUFA in tissue lipids corresponds to their proportion in the father form, whereas the corresponding values for SFA and PUFA are closer to the father form and much higher (P≤ 0.01) than in the mother form. A 100 g portion of the SSZ tissue for consumption contains a higher total amount of n-3 acids as well as EPA and DHA than the parent fish, with a higher difference in comparison with Siberian sturgeon.

The present study evaluated growth performance, body yield and blood samples of Nile tilapia (Oreochromis niloticus) after dietary supplementation with Saccharomyces cerevisiae. Sixty Nile tilapia (155.5 ± 2.15 g) were randomly distributed in ten experimental units of 800 L (six fish per unit) and divided into two groups with five replications each. One group of fish received a diet containing S. cerevisiae (SAC), while the control (CTL) group received a diet without the addition of the yeast. The fish remained in an experimental regime for 120 days. After this period, all fish were submitted to biometric analysis to determine growth performance, and blood samples were collected for haematological analysis. Subsequently, the fish were euthanized and eviscerated for further evaluation, including carcass weight, fillet yield, and centesimal fillet composition, as well as viscerosomatic, hepatosomatic and digestivesomatic indexes. Fish fed the diet containing S. cerevisiae showed a significant increase in the number of erythrocytes, lymphocytes, and monocytes, as well as weekly weight gain, feed efficiency, protein retention rate and productivity. Furthermore, in animals of the SAC group, pH in meat was reduced, and fillet yield was increased by 6.53 % compared to the control group. Therefore, dietary supplementation with S. cerevisiae showed probiotic properties in Nile tilapia during the fattening phase, along with the improvement of haematological indexes and optimization of zootechnical indicators relevant to the tilapia industry. • S. cerevisiae increased fillet yield in Nile tilapia. • S. cerevisiae increase growth performance of Nile tilapia. • S. cerevisiae reduced pH in tilapia fillet. [ABSTRACT FROM AUTHOR]

Rigor-index in market-size striped catfish (Pangasianodon hypophthalmus, locally called Thai-Pangas) was determined to assess fillet yield for production of value-added products. In whole fish, rigor started within 1 hr after death under both iced and room temperature conditions while rigor-index reached a maximum of 72.23% within 8 hr and 85.5% within 5 hr at room temperature and iced condition, respectively, which was fully relaxed after 22 hr under both storage conditions. Post-mortem muscle pH decreased to 6.8 after 2 hr, 6.2 after 8 hr and sharp increase to 6.9 after 9 hr. There was a positive correlation between rigor progress and pH shift in fish fillets. Hand filleting was done post-rigor and fillet yield experiment showed 50.4±2.1% fillet, 8.0±0.2% viscera, 8.0±1.3% skin and 32.0±3.2% carcass could be obtained from Thai-Pangas. Proximate composition analysis of four regions of Thai-Pangas viz., head region, middle region, tail region and viscera revealed moisture 78.36%, 81.14%, 81.45% and 57.33%; protein 15.83%, 15.97%, 16.14% and 17.20%; lipid 4.61%, 1.82%, 1.32% and 24.31% and ash 1.09%, 0.96%, 0.95% and 0.86%, respectively indicating suitability of Thai-Pangas for production of value-added products such as fish fillets.

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The shape of an object can be described by a finite number of points called landmarks. Nowadays, there are no systems available for the automated landmarks detection. However, the implementation of such method would be of elevated interest in the food industrial processing. The evaluation of cattle carcass and fish quality requires the time-consuming and manual positioning of landmarks, with still too subjective results. The aim of this work is the application of an innovative algorithm, called backwarping, for the automated positioning of landmarks onto the beef carcass and sea bass profiles. This algorithm combines the automated extraction of the outlines with the thin-plate spline interpolation algorithm. The proposed approach is applied to two very different cases in order to stress the high performing versatility of the procedure. We firstly carried out a calibration phase where the landmarks were manually placed. Then we applied the automated procedure for comparison. The errors in the automated landmarks positioning has been always lower than 3 % and the percentage standard error of prediction was always lower than 1.5 %. The approach for both study cases showed its feasibility in being easily extended to the processing of a diversified variety of food products, such as poultry, bakery or 'pasta.' Moreover, due to its versatility, the technique could be also applied within the zoological and biomedical fields, given the obtained high levels of accuracy in the automated landmark positioning. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the growth performance, expression of genes related to the metabolism of sulfur-containing amino acids, and flesh quality of large Nile tilapia (Oreochromis niloticus). Fish (n = 120; 1199 ± 46 g) were randomly distributed into four groups and each fish group was hand-fed a basal diet not supplemented (CON) or supplemented with methionine (MET), taurine (TAU), and methionine and taurine (MET+TAU) until apparent satiety for seven weeks. Compared to CON group, the fish group on the MET diet experienced increased in final body weight, protein retention efficiency, and fillet yield by 62.83 g, 9.82%, and 1.31%, respectively (p < 0.05). These results were linked to the down-regulation of cystathionine β-synthase (CBS) and cysteine dioxygenase (CDO) gene controlled by methionine supplementation. Moreover, up-regulation of the adenosylhomocysteine (AHCY) gene in fish offered TAU diet as a metabolic response to methionine deprivation. Furthermore, taurine prevented color deterioration and increased fillet hardness and chewiness attributes as compared to CON group (p < 0.05). Overall, this study indicated a marked effect of dietary methionine on growth performance, particularly fillet yield, and notable synergic effect of methionine and taurine preventing color deterioration and increasing fillet hardness. [Display omitted] • Methionine enhanced growth, feed efficiency, protein retention, and fillet yield of fish. • Fish fed methionine supplemented diets showed down-regulated expression of CBS and CDO genes. • Taurine addition increased mRNA levels of AHC gene in response to methionine deprivation. • Methionine and taurine in combination effectively prevented color deterioration and enhanced fillet hardness and chewiness. [ABSTRACT FROM AUTHOR]

Abstract: Selection to improve processing yields relies on sib selection, in which live candidates are ranked according to their family breeding value. This approach limits genetic progress, as it only exploits genetic variability between families and not within them. Indirect criteria measured on live candidates could overcome this limitation. The present study (1) proposes a procedure to identify indirect criteria to predict processing yields in rainbow trout (head, carcass and fillet yields), (2) estimates genetic parameters of these indirect criteria, and (3) predicts relative genetic gains in processing yields using full-sib selection or indirect individual selection on those indirect criteria. DNA-pedigreed all-female rainbow trout Oncorhynchus mykiss (n =2029, 1631.0±355.6g) from 600 families produced from 100 sires and 60 dams were characterized by external and internal non-lethal morphological measures using digital pictures and real time ultrasound tomography. Nineteen landmarks were recorded on the digital pictures to define the outline of the body, head and lateral line. Their coordinates were used to calculate different lengths, heights and areas. Five different internal thicknesses were measured by ultrasound tomography. In the first phase of this study, processing yields were predicted using multiple linear regressions including both external and internal morphometric variables. In a second phase, the heritability of the predicted values and their genetic correlations with real processing yields were estimated using animal models. Predicted yields exhibited intermediate heritabilities (0.25–0.28) that were half the value of heritabilities for real processing yields (0.47–0.55), but had high genetic correlations with these real yields (0.87–0.90). The relative efficiency of indirect selection (IS) on these indirect criteria was compared to theoretical mass selection (MS) or sib selection (FS) with different family sizes (10 or 100) and two different selection pressures (10% or 40%). At the same selection pressure (10%, with 100 sibs per family %), full-sib selection created genetic progress 49.6% to 60.5% higher than indirect selection according to the processing yield targeted. However, when sib-selection pressure was limited to a more realistic between family selection pressure (40% and 10 sibs per family), indirect selection with 10% selection pressure was 21.9% to 32.7% more efficient than sib selection. [Copyright &y& Elsevier]

Abstract: Genetic parameters of production traits (growth, carcass yield, fillet yield) and bony tissues (head and vertebral axis) were estimated for large all-female rainbow trout Oncorhynchus mykiss reared in freshwater. Genetic parameters were estimated using REML at 16months of age (1636g) on 1962 DNA-assigned progenies from a partial factorial mating design with 60 dams and 100 sex-reversed sires. Most traits presented medium to high heritability (0.37 to 0.54). A high genetic correlation (rA =0.97) was found between fillet yield and headless gutted carcass yield (or HGCarc%). Due to its higher heritability and high genetic correlation with fillet yield, selection on HGCarc% should result in a 50% increase in selection efficiency on fillet yield by reducing operator-linked variability at filleting. However, strong negative genetic correlations were estimated between body weight or fillet yield and bony tissue development as head yield or the head and vertebral column yield (−0.48 to −0.57). Ten generations of selection on body weight (or fillet yield) are, therefore, predicted to decrease the relative head development by 25 to 30% for slaughtering at constant age. As it is impossible to disentangle this result from a correlation that is only mathematically determined, this result needs further investigations. If yields are corrected according to their allometric relationship with body weight, only selection for fillet yield will decrease the proportion of bony tissues for a slaughtering at a constant body weight. Whatever the final objective of selection (to increase body weight or to shorten the production cycle at constant body weight), it is concluded that at least selection on fillet yield will affect the relative head and the vertebral axis development and that selection on growth may affect bony tissue development. These results are discussed in relation to the past results from livestock breeding, resource energy allocation theory and a future improvement of robustness by selection. [Copyright &y& Elsevier]

Abstract: There is little published information on genetic covariance estimates among meat yield traits in Nile tilapia. Longitudinal genetic analyses to evaluate patterns of environmental and genetic covariances among such traits during growth would help to establish selection criteria and predict direct and correlated response to selection. Accordingly, longitudinal genetic studies from 106 to 245days of age were performed by random regression models for carcass and fillet weights and yields in Nile tilapia. For each analysis, the statistical model included random family common environmental and genetic effects and assuming heterogeneity of residual variances. For carcass and fillet yield, genetic correlations between closely paired ages (from 140 to 200days) were higher (>0.80) than those separated by moderate (>0.40) or longer (approaching zero) intervals. For carcass and fillet weight, genetic correlations when both ages were greater than 125days post-hatching were larger than 0.60, and those when both ages were greater than 149days post-hatching were larger than 0.80. Heritability estimates for fillet and carcass yields ranged from moderate (0.12) to high (0.52), suggesting the likelihood that selection programs could improve these traits. The manner in which fillets were removed seems to influence the results. Heritability estimates for carcass and fillet weight ranged from high (0.52) to low (0.01). The family common environmental effect was important for reducing the heritability estimates of these two traits, probably due to high correlation of each trait to body weight at slaughter, which is substantially affected by the common family environmental effect. Accordingly, to increase the accuracy of predicted breeding values for these traits, it is important to reduce family effects by minimizing the duration during which families are reared separately, then tagging individual fish and initiating communal stocking at as early a life stage as possible. Based upon estimated genetic parameters among the traits, direct selection for body weight, carcass weight and fillet weight is not recommended if the breeding goal is to increase fillet yield as a correlated response. Contrarily, the high genetic correlations between body weight and fillet and carcass weights (>0.98) suggest that body weight could be used as a selection criterion to avoid slaughtering potential breeders to acquire data and to achieve higher selection intensity. [Copyright &y& Elsevier]

Abstract: With the objective of how to best improve fillet weight in Nile tilapia (Oreochromis niloticus) through selection round and gutted body weight and fillet weight were recorded at harvest over four generations (G0, G1, G2 and G3) and from which the following traits were derived: Fillet yield (fillet weight×100/round weight), non-edible part of the fish (NEP=round weight−fillet weight), and non-meat part of the gutted weight (NMP=gutted weight−fillet weight). The round weight was recorded on 42,795 offspring of 327 sires and 422 dams, and the other traits on a random sample of 3361 of the offspring of 277 sires and 359 dams. The fish were reared in net-cages in a lake or in earthen ponds. Selection was performed for harvest weight and fillet yield with an equal relative economic weight (50%) on each trait. The heritabilities for round, gutted and fillet weight, NEP and NMP were all moderate (0.16–0.19) and lower for fillet yield (0.06). The effect common to full-sibs (c2) accounted for a large proportion of the phenotypic variance for all traits (0.11–0.19). The genetic correlation between round weight of fish reared in cages and in ponds was unity (1.00), indicating no genotype by environment interaction for this trait. The genetic correlations between round, gutted and fillet weights were all close to unity, as were the genetic correlations of round and fillet weight with the calculated traits NEP and NMP. The close to unity genetic correlation between round body weight and fillet weight indicates that genetic improvement of one of the traits without achieving a proportional genetic change in the other is difficult or even impossible. This implies that improvement of fillet yield through direct selection is difficult to achieve. Still, based on the current results, fillet yield is expected to increase with increasing body weight, both genetically and phenotypically. However, if increased growth leads to harvest at a younger age rather than higher weight, response in fillet yield may not be observed. Improvement of fillet weight can be obtained through selection for increased round body weight, a more efficient strategy as the trait can be recorded on live breeding candidates and as higher economic weight can be put on this trait instead of on fillet yield. [Copyright &y& Elsevier]

Abstract: The influence of catching and processing factors on fillet yield, gaping and number of nematodes in cod (Gadus morhua) was studied. The study was carried out in co-operation with four Icelandic fishery companies. Data on catch, condition of raw material and processing were linked together by tracing the cod from catch through primary processing. Analysis of these data show that important variables for profitability in the fish industry are strongly correlated to controllable variables, such as catch ground, catch method and age of raw material when processed. The results can aid in decision making for catching and processing cod, provided that strong relationship exist between different links in the value chain of cod. [Copyright &y& Elsevier]