The impact of two dietary organic acids (OAs) on nutrient digestibility and intestinal morphology... more The impact of two dietary organic acids (OAs) on nutrient digestibility and intestinal morphology was determined in Nile tilapia under conditions of dissolved oxygen in the water: normoxia and hypoxia. Four diets designated as control (0 g/kg organic acid salt), KDF (2 g/kg potassium diformate), CAB (2 g/kg calcium butyrate) and their combination (4 g/kg of a mixture of KDF and CAB, ration 1:1) were formulated with 520 g/kg of soybean meal in order to produce soybean meal enteritis‐like symptoms. The four diets were tested first under normoxic conditions (6 mg/L) for a period of 5 weeks, followed by a test period under hypoxic conditions (3 mg/L). The results showed that OAs were unable to significantly improve growth and nutrient digestibility under normoxic conditions but under hypoxic conditions, there was a significant enhancement of the growth and nutrient digestibility. Fish fed OA‐supplemented diets showed improvements in the intestinal morphology under the normoxic conditions, and these effects were more pronounced under the hypoxic conditions. Experimental findings suggest that OAs can improve nutrient digestibility and intestinal morphology under hypoxic conditions. A synergistic effect by the combination of formic and butyric acid on growth, digestibility and intestinal morphology was not found.
The present study assessed the effect of different feed ingredients on nutrient apparent digestib... more The present study assessed the effect of different feed ingredients on nutrient apparent digestibility coefficients (ADC), nitrogen/energy balance and morphology changes in the intestine of Nile tilapia; using a control diet and six test diets, in which the following six ingredients were included at 30%: hydrolysed feather meal (HFM), soybean meal (SBM), rice bran (RB), rapeseed meal (RM), sunflower meal (SFM) and dried distillers grains with solubles (DDGS). The proximal, middle and distal intestine was processed for quantitative histology counting the number of goblet cells (GC), and measuring the thickness of lamina propria (LP) and submucosa (SM). The study showed that the ADC of protein in raw materials were highest in SBM (92.2%), followed by SFM (90.2%), DDGS (89.2%), RM (87.8%), HFM (86.9%) and RB (84.0%). The nutrient ADCs had no correlation with intestinal morphology changes. Only the SBM diet caused noticeable changes in intestinal morphology such as an increase the thickness of SM and LP and the number of GC. The diet composition, however, altered the protein efficiency and the maintenance energy equirement. Protein retention efficiency was the lowest in fish fed HFM and the highest in RB. The highest maintenance energy requirements were observed in HFM and SBM treatments.
The octopus is one of the most important marine resources in Portugal, especially in the South, t... more The octopus is one of the most important marine resources in Portugal, especially in the South, the Algarve region. The fishing gears mostly used are the “alcatruz” and the “covo”. The “alcatruz” is a shelter-pot traditionally made of clay, with an amphora shape, but recently plastic cylindrical pots were introduced and became more popular. “Covos” are baited metal cage-traps covered by a plastic net. Although very popular among fishermen, the traditional “alcatruz” made of clay has been replaced by cylindrical plastic pots with great success, due to its resistance to brake. In an attempt to continue using the additional amphora-shape, a new type of plastic pot was built in association with fishermen. To study the behaviour of the common octopus (Octopus vulgaris) towards the traditional amphora clay shelter-pot, the cylindrical plastic shelter-pot and the new amphora plastic shelter-pot, several experiments were performed in controlled tanks. Three main questions were attempted to answer concerning the preferences of the common octopus towards the pots: 1) What kind of material: plastic or clay (traditional); 2) What shape: cylindrical or amphora (traditional); 3) What colour: white, black or red brick (traditional). The results showed no particular preference towards the material of the fishing gear; a strong preference for the traditional amphora shape; and a strong preference for the black colour.
In book: Biodiversity in the fisheries of Algarve (South Portugal)Publisher: University of Algarve, 2007
Cephalopods are not only the most complex group in the phylum Mollusca, but also in all the inver... more Cephalopods are not only the most complex group in the phylum Mollusca, but also in all the invertebrate phyla. They are exclusively marine animals, living in all oceans, from surface waters to the deep sea (over 5,000 m). Cephalopods first appeared over 450 million years ago but most became extinct 150 million years ago. More than 10,000 species are described in the fossil record, with an estimated 700 species existent today. The taxonomy of cephalopods is at present under discussion, and the classification adopted here divides all living cephalopods into 2 sbclasses: Coleoidea, which includes squids, cuttlefishes, octopuses and vampires, and Nautiloidea. Cephalopods are soft-bodied animals, with a well developed head, a ring of arms surrounding the head and a body that consists of a muscular mantle, a mantle cavity (containing the internal organs), and fins (when present). A shell may be external (Nautilus), internal (cuttlefish and squids), vestigial (benthic octopuses) or lacking altogether (octopuses and vampire squid). Most cephalopods have numerous chromatophores (pigment cells) and iridocytes (iridescent cells) in the skin, which permit rapid changes in colour and pattern, an integral part of their behaviour. The size of adult cephalopods ranges from less than 1 cm (Sepiolidae) to more than 20 m total length (Colossal squid). Individuals may be solitary, with territorial behaviour (octopus), or live in schools (squids). Most cephalopod functional systems are distinct from those of other molluscs, showing a development comparable to that of vertebrates. The nervous system, for example, includes eyes with lens focusing images on a retina. Cephalopods are active predators that feed upon crustaceans, fish, bivalves and other cephalopods. Their speed, high mobility and powerful visual system, make them probably the most efficient hunters of the oceans. They have strong mandibles, with “parrot” beak shape, in the buccal cavity, on the base of which lies the radula and two pairs of salivary glands, one of which can be poisonous. Cephalopods are also prey of another predators like seabirds, whales, seals and fish. All cephalopods have separate sexes and most show external sexual dimorphism. Males of many species have 1-2 modified arm(s) (ectocotylus) for transferring spermatophores (tubular sperm packets) to females during mating. Mating is often preceded by courtship behaviour. Development of cephalopods is direct, without true metamorphic stages. Hatchlings can look like miniatures of the adult (cuttlefish), or undergo gradual changes during development (octopus). Life expectancy of most coleoid cephalopods range from few months to 1-2 years. A general consensus exists that all coleoids die after the spawning period, in spite of the high variability in reproductive strategy (total spawning, to prolonged, intermittent, etc.).
The impact of two dietary organic acids (OAs) on nutrient digestibility and intestinal morphology... more The impact of two dietary organic acids (OAs) on nutrient digestibility and intestinal morphology was determined in Nile tilapia under conditions of dissolved oxygen in the water: normoxia and hypoxia. Four diets designated as control (0 g/kg organic acid salt), KDF (2 g/kg potassium diformate), CAB (2 g/kg calcium butyrate) and their combination (4 g/kg of a mixture of KDF and CAB, ration 1:1) were formulated with 520 g/kg of soybean meal in order to produce soybean meal enteritis‐like symptoms. The four diets were tested first under normoxic conditions (6 mg/L) for a period of 5 weeks, followed by a test period under hypoxic conditions (3 mg/L). The results showed that OAs were unable to significantly improve growth and nutrient digestibility under normoxic conditions but under hypoxic conditions, there was a significant enhancement of the growth and nutrient digestibility. Fish fed OA‐supplemented diets showed improvements in the intestinal morphology under the normoxic conditions, and these effects were more pronounced under the hypoxic conditions. Experimental findings suggest that OAs can improve nutrient digestibility and intestinal morphology under hypoxic conditions. A synergistic effect by the combination of formic and butyric acid on growth, digestibility and intestinal morphology was not found.
The present study assessed the effect of different feed ingredients on nutrient apparent digestib... more The present study assessed the effect of different feed ingredients on nutrient apparent digestibility coefficients (ADC), nitrogen/energy balance and morphology changes in the intestine of Nile tilapia; using a control diet and six test diets, in which the following six ingredients were included at 30%: hydrolysed feather meal (HFM), soybean meal (SBM), rice bran (RB), rapeseed meal (RM), sunflower meal (SFM) and dried distillers grains with solubles (DDGS). The proximal, middle and distal intestine was processed for quantitative histology counting the number of goblet cells (GC), and measuring the thickness of lamina propria (LP) and submucosa (SM). The study showed that the ADC of protein in raw materials were highest in SBM (92.2%), followed by SFM (90.2%), DDGS (89.2%), RM (87.8%), HFM (86.9%) and RB (84.0%). The nutrient ADCs had no correlation with intestinal morphology changes. Only the SBM diet caused noticeable changes in intestinal morphology such as an increase the thickness of SM and LP and the number of GC. The diet composition, however, altered the protein efficiency and the maintenance energy equirement. Protein retention efficiency was the lowest in fish fed HFM and the highest in RB. The highest maintenance energy requirements were observed in HFM and SBM treatments.
The octopus is one of the most important marine resources in Portugal, especially in the South, t... more The octopus is one of the most important marine resources in Portugal, especially in the South, the Algarve region. The fishing gears mostly used are the “alcatruz” and the “covo”. The “alcatruz” is a shelter-pot traditionally made of clay, with an amphora shape, but recently plastic cylindrical pots were introduced and became more popular. “Covos” are baited metal cage-traps covered by a plastic net. Although very popular among fishermen, the traditional “alcatruz” made of clay has been replaced by cylindrical plastic pots with great success, due to its resistance to brake. In an attempt to continue using the additional amphora-shape, a new type of plastic pot was built in association with fishermen. To study the behaviour of the common octopus (Octopus vulgaris) towards the traditional amphora clay shelter-pot, the cylindrical plastic shelter-pot and the new amphora plastic shelter-pot, several experiments were performed in controlled tanks. Three main questions were attempted to answer concerning the preferences of the common octopus towards the pots: 1) What kind of material: plastic or clay (traditional); 2) What shape: cylindrical or amphora (traditional); 3) What colour: white, black or red brick (traditional). The results showed no particular preference towards the material of the fishing gear; a strong preference for the traditional amphora shape; and a strong preference for the black colour.
In book: Biodiversity in the fisheries of Algarve (South Portugal)Publisher: University of Algarve, 2007
Cephalopods are not only the most complex group in the phylum Mollusca, but also in all the inver... more Cephalopods are not only the most complex group in the phylum Mollusca, but also in all the invertebrate phyla. They are exclusively marine animals, living in all oceans, from surface waters to the deep sea (over 5,000 m). Cephalopods first appeared over 450 million years ago but most became extinct 150 million years ago. More than 10,000 species are described in the fossil record, with an estimated 700 species existent today. The taxonomy of cephalopods is at present under discussion, and the classification adopted here divides all living cephalopods into 2 sbclasses: Coleoidea, which includes squids, cuttlefishes, octopuses and vampires, and Nautiloidea. Cephalopods are soft-bodied animals, with a well developed head, a ring of arms surrounding the head and a body that consists of a muscular mantle, a mantle cavity (containing the internal organs), and fins (when present). A shell may be external (Nautilus), internal (cuttlefish and squids), vestigial (benthic octopuses) or lacking altogether (octopuses and vampire squid). Most cephalopods have numerous chromatophores (pigment cells) and iridocytes (iridescent cells) in the skin, which permit rapid changes in colour and pattern, an integral part of their behaviour. The size of adult cephalopods ranges from less than 1 cm (Sepiolidae) to more than 20 m total length (Colossal squid). Individuals may be solitary, with territorial behaviour (octopus), or live in schools (squids). Most cephalopod functional systems are distinct from those of other molluscs, showing a development comparable to that of vertebrates. The nervous system, for example, includes eyes with lens focusing images on a retina. Cephalopods are active predators that feed upon crustaceans, fish, bivalves and other cephalopods. Their speed, high mobility and powerful visual system, make them probably the most efficient hunters of the oceans. They have strong mandibles, with “parrot” beak shape, in the buccal cavity, on the base of which lies the radula and two pairs of salivary glands, one of which can be poisonous. Cephalopods are also prey of another predators like seabirds, whales, seals and fish. All cephalopods have separate sexes and most show external sexual dimorphism. Males of many species have 1-2 modified arm(s) (ectocotylus) for transferring spermatophores (tubular sperm packets) to females during mating. Mating is often preceded by courtship behaviour. Development of cephalopods is direct, without true metamorphic stages. Hatchlings can look like miniatures of the adult (cuttlefish), or undergo gradual changes during development (octopus). Life expectancy of most coleoid cephalopods range from few months to 1-2 years. A general consensus exists that all coleoids die after the spawning period, in spite of the high variability in reproductive strategy (total spawning, to prolonged, intermittent, etc.).
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Papers by Joao Sendao
The four diets were tested first under normoxic conditions (6 mg/L) for a period of 5 weeks, followed by a test period under hypoxic conditions (3 mg/L). The results showed that OAs were unable to significantly improve growth and nutrient digestibility under normoxic conditions but under hypoxic conditions, there was a significant enhancement of the growth and nutrient digestibility. Fish fed OA‐supplemented diets showed improvements in the intestinal morphology under the normoxic conditions, and these effects were more pronounced under the hypoxic conditions.
Experimental findings suggest that OAs can improve nutrient digestibility and intestinal morphology under hypoxic conditions. A synergistic effect by the combination of formic and butyric acid on growth, digestibility and intestinal morphology was not found.
The nutrient ADCs had no correlation with intestinal morphology changes. Only the SBM diet caused noticeable changes in intestinal morphology such as an increase the thickness of SM and LP and the number of GC. The diet composition, however, altered the protein efficiency and the maintenance energy equirement. Protein retention efficiency was the lowest in fish fed HFM and the highest in RB. The highest maintenance energy requirements were observed in HFM and SBM treatments.
Although very popular among fishermen, the traditional “alcatruz” made of clay has been replaced by cylindrical plastic pots with great success, due to its resistance to brake. In an attempt to continue using the additional amphora-shape, a new type of plastic pot was built in association with fishermen.
To study the behaviour of the common octopus (Octopus vulgaris) towards the traditional amphora clay shelter-pot, the cylindrical plastic shelter-pot and the new amphora plastic shelter-pot, several experiments were performed in controlled tanks. Three main questions were attempted to answer concerning the preferences of the common octopus towards the pots: 1) What kind of material: plastic or clay (traditional); 2) What shape: cylindrical or amphora (traditional); 3) What colour: white, black or red brick (traditional). The results showed no particular preference towards the material of the fishing gear; a strong preference for the traditional amphora shape; and a strong preference for the black colour.
Books by Joao Sendao
Cephalopods first appeared over 450 million years ago but most became extinct 150 million years ago.
More than 10,000 species are described in the fossil record, with an estimated 700 species existent today.
The taxonomy of cephalopods is at present under discussion, and the classification adopted here divides all living cephalopods into 2 sbclasses: Coleoidea, which includes squids, cuttlefishes, octopuses and vampires, and Nautiloidea.
Cephalopods are soft-bodied animals, with a well developed head, a ring of arms surrounding the head and a body that consists of a muscular mantle, a mantle cavity (containing the internal organs), and fins (when
present). A shell may be external (Nautilus), internal (cuttlefish and squids), vestigial (benthic octopuses) or lacking altogether (octopuses and vampire squid). Most cephalopods have numerous chromatophores (pigment cells) and iridocytes (iridescent cells) in the skin, which permit rapid changes in colour and pattern, an integral part of their behaviour.
The size of adult cephalopods ranges from less than 1 cm (Sepiolidae) to more than 20 m total length (Colossal squid). Individuals may be solitary, with territorial behaviour (octopus), or live in schools (squids).
Most cephalopod functional systems are distinct from those of other molluscs, showing a development comparable to that of vertebrates. The nervous system, for example, includes eyes with lens focusing images on a retina.
Cephalopods are active predators that feed upon crustaceans, fish, bivalves and other cephalopods. Their speed, high mobility and powerful visual system, make them probably the most efficient hunters of the oceans.
They have strong mandibles, with “parrot” beak shape, in the buccal cavity, on the base of which lies the radula and two pairs of salivary glands, one of which can be poisonous. Cephalopods are also prey of another predators like seabirds, whales, seals and fish.
All cephalopods have separate sexes and most show external sexual dimorphism. Males of many species have 1-2 modified arm(s) (ectocotylus) for transferring spermatophores (tubular sperm packets) to females during mating. Mating is often preceded by courtship behaviour. Development of cephalopods is direct, without true metamorphic stages. Hatchlings can look like miniatures of the adult (cuttlefish), or undergo gradual changes during development (octopus).
Life expectancy of most coleoid cephalopods range from few months to 1-2 years. A general consensus exists that all coleoids die after the spawning period, in spite of the high variability in reproductive strategy
(total spawning, to prolonged, intermittent, etc.).
The four diets were tested first under normoxic conditions (6 mg/L) for a period of 5 weeks, followed by a test period under hypoxic conditions (3 mg/L). The results showed that OAs were unable to significantly improve growth and nutrient digestibility under normoxic conditions but under hypoxic conditions, there was a significant enhancement of the growth and nutrient digestibility. Fish fed OA‐supplemented diets showed improvements in the intestinal morphology under the normoxic conditions, and these effects were more pronounced under the hypoxic conditions.
Experimental findings suggest that OAs can improve nutrient digestibility and intestinal morphology under hypoxic conditions. A synergistic effect by the combination of formic and butyric acid on growth, digestibility and intestinal morphology was not found.
The nutrient ADCs had no correlation with intestinal morphology changes. Only the SBM diet caused noticeable changes in intestinal morphology such as an increase the thickness of SM and LP and the number of GC. The diet composition, however, altered the protein efficiency and the maintenance energy equirement. Protein retention efficiency was the lowest in fish fed HFM and the highest in RB. The highest maintenance energy requirements were observed in HFM and SBM treatments.
Although very popular among fishermen, the traditional “alcatruz” made of clay has been replaced by cylindrical plastic pots with great success, due to its resistance to brake. In an attempt to continue using the additional amphora-shape, a new type of plastic pot was built in association with fishermen.
To study the behaviour of the common octopus (Octopus vulgaris) towards the traditional amphora clay shelter-pot, the cylindrical plastic shelter-pot and the new amphora plastic shelter-pot, several experiments were performed in controlled tanks. Three main questions were attempted to answer concerning the preferences of the common octopus towards the pots: 1) What kind of material: plastic or clay (traditional); 2) What shape: cylindrical or amphora (traditional); 3) What colour: white, black or red brick (traditional). The results showed no particular preference towards the material of the fishing gear; a strong preference for the traditional amphora shape; and a strong preference for the black colour.
Cephalopods first appeared over 450 million years ago but most became extinct 150 million years ago.
More than 10,000 species are described in the fossil record, with an estimated 700 species existent today.
The taxonomy of cephalopods is at present under discussion, and the classification adopted here divides all living cephalopods into 2 sbclasses: Coleoidea, which includes squids, cuttlefishes, octopuses and vampires, and Nautiloidea.
Cephalopods are soft-bodied animals, with a well developed head, a ring of arms surrounding the head and a body that consists of a muscular mantle, a mantle cavity (containing the internal organs), and fins (when
present). A shell may be external (Nautilus), internal (cuttlefish and squids), vestigial (benthic octopuses) or lacking altogether (octopuses and vampire squid). Most cephalopods have numerous chromatophores (pigment cells) and iridocytes (iridescent cells) in the skin, which permit rapid changes in colour and pattern, an integral part of their behaviour.
The size of adult cephalopods ranges from less than 1 cm (Sepiolidae) to more than 20 m total length (Colossal squid). Individuals may be solitary, with territorial behaviour (octopus), or live in schools (squids).
Most cephalopod functional systems are distinct from those of other molluscs, showing a development comparable to that of vertebrates. The nervous system, for example, includes eyes with lens focusing images on a retina.
Cephalopods are active predators that feed upon crustaceans, fish, bivalves and other cephalopods. Their speed, high mobility and powerful visual system, make them probably the most efficient hunters of the oceans.
They have strong mandibles, with “parrot” beak shape, in the buccal cavity, on the base of which lies the radula and two pairs of salivary glands, one of which can be poisonous. Cephalopods are also prey of another predators like seabirds, whales, seals and fish.
All cephalopods have separate sexes and most show external sexual dimorphism. Males of many species have 1-2 modified arm(s) (ectocotylus) for transferring spermatophores (tubular sperm packets) to females during mating. Mating is often preceded by courtship behaviour. Development of cephalopods is direct, without true metamorphic stages. Hatchlings can look like miniatures of the adult (cuttlefish), or undergo gradual changes during development (octopus).
Life expectancy of most coleoid cephalopods range from few months to 1-2 years. A general consensus exists that all coleoids die after the spawning period, in spite of the high variability in reproductive strategy
(total spawning, to prolonged, intermittent, etc.).