Digestible energy as a criterion for the development of diets for the African sharptooth catfish, Clarias gariepinus (Pisces: Clariidae)
- Authors: Rouhani, Q A
- Date: 1993
- Subjects: Clariidae , Catfishes -- Africa , Catfishes -- Nutrition -- Requirements -- Africa , Catfishes , Clarias
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5259 , http://hdl.handle.net/10962/d1005103
- Description: Based on a number of attributes, the African sharptooth catfish, Clarias gariepinus is an ideal aquaculture species. Much work has been undertaken on developing the technology for the commercial culture of the species inclusive of determining the nutritional requirements for cost effective feed formulation. However, digestible energy (DE) values for specific feed ingredients were unknown. As DE values are not interchangeable between species, this study set out to determine the DE values for conventional and unconventional feed-ingredients for the formulation of an optimal feed. The ultimate goal in feed formulation is to produce a diet that supports the maximum production at the least cost. The indirect method was found to be most suitable in obtaining DE values for the catfish. Feed samples were marked by adding 2% chromic oxide as an inert indicator. The fish were then force-fed and faecal samples were obtained from the hindgut by stripping the fish 10 hours after feeding as this was found to be when the hind-gut was at its fullest and the feed maximally digested. A linear based computer programme was used to formulate experimental diets using the established DE values as an additional variable. The formulated feed was tested and compared to a commercial catfish diet and a standard reference diet (H-440). All of the newly formulated feeds were found to be cheaper to manufacture (by between 5 and 10%). Statistically (ANOVA), all of the experimental diets resulted in higher specific growth rates (SGR) than the standard reference diet. The commercial diet also resulted in a lower SGR than those experimental diets with similar protein levels.
- Full Text:
- Date Issued: 1993
- Authors: Rouhani, Q A
- Date: 1993
- Subjects: Clariidae , Catfishes -- Africa , Catfishes -- Nutrition -- Requirements -- Africa , Catfishes , Clarias
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5259 , http://hdl.handle.net/10962/d1005103
- Description: Based on a number of attributes, the African sharptooth catfish, Clarias gariepinus is an ideal aquaculture species. Much work has been undertaken on developing the technology for the commercial culture of the species inclusive of determining the nutritional requirements for cost effective feed formulation. However, digestible energy (DE) values for specific feed ingredients were unknown. As DE values are not interchangeable between species, this study set out to determine the DE values for conventional and unconventional feed-ingredients for the formulation of an optimal feed. The ultimate goal in feed formulation is to produce a diet that supports the maximum production at the least cost. The indirect method was found to be most suitable in obtaining DE values for the catfish. Feed samples were marked by adding 2% chromic oxide as an inert indicator. The fish were then force-fed and faecal samples were obtained from the hindgut by stripping the fish 10 hours after feeding as this was found to be when the hind-gut was at its fullest and the feed maximally digested. A linear based computer programme was used to formulate experimental diets using the established DE values as an additional variable. The formulated feed was tested and compared to a commercial catfish diet and a standard reference diet (H-440). All of the newly formulated feeds were found to be cheaper to manufacture (by between 5 and 10%). Statistically (ANOVA), all of the experimental diets resulted in higher specific growth rates (SGR) than the standard reference diet. The commercial diet also resulted in a lower SGR than those experimental diets with similar protein levels.
- Full Text:
- Date Issued: 1993
Descriptions of two new species of West African amphiliid catfishes (Siluroidei: Amphiliidae)
- Skelton, Paul H (Paul Harvey), J.L.B. Smith Institute of Ichthyology
- Authors: Skelton, Paul H (Paul Harvey) , J.L.B. Smith Institute of Ichthyology
- Date: 1989-08
- Subjects: Catfishes , Siluridae , Fishes -- South Africa
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/70324 , vital:29645 , Margaret Smith Library (South African Institute for Aquatic Biodiversity (SAIAB)) Periodicals Margaret Smith Library (South African Institute for Aquatic Biodiversity (SAIAB))
- Description: Online version of original print edition of the Special Publication of the J.L.B. Smith Institute of Ichthyology; No. 48 , Two new amphiliid catfish species from west Africa are described. A new Paramphilius from the Little Scarcies River basin in Guinea, is the third species of the genus from that area. It has a relatively deeper body and longer fins than other upper Guinean Paramphilius species. The new species of Doumea from the Cross River in Nigeria and Cameroons is characterised by a long predorsal length and a relatively short stout caudal peduncle.
- Full Text:
- Date Issued: 1989-08
- Authors: Skelton, Paul H (Paul Harvey) , J.L.B. Smith Institute of Ichthyology
- Date: 1989-08
- Subjects: Catfishes , Siluridae , Fishes -- South Africa
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/70324 , vital:29645 , Margaret Smith Library (South African Institute for Aquatic Biodiversity (SAIAB)) Periodicals Margaret Smith Library (South African Institute for Aquatic Biodiversity (SAIAB))
- Description: Online version of original print edition of the Special Publication of the J.L.B. Smith Institute of Ichthyology; No. 48 , Two new amphiliid catfish species from west Africa are described. A new Paramphilius from the Little Scarcies River basin in Guinea, is the third species of the genus from that area. It has a relatively deeper body and longer fins than other upper Guinean Paramphilius species. The new species of Doumea from the Cross River in Nigeria and Cameroons is characterised by a long predorsal length and a relatively short stout caudal peduncle.
- Full Text:
- Date Issued: 1989-08
Plotonus nkunga, a new species of catfish from South Africa, with a redescription of Plotosus limbatus Valenciennes and key to the species of Plotosus (Siluriformes: Plotosidae)
- Gomon, Janet R, Taylor, William Ralph, J.L.B. Smith Institute of Ichthyology
- Authors: Gomon, Janet R , Taylor, William Ralph , J.L.B. Smith Institute of Ichthyology
- Date: 1982-08
- Subjects: Catfishes
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/69871 , vital:29590 , Margaret Smith Library (South African Institute for Aquatic Biodiversity (SAIAB)) Periodicals Margaret Smith Library (South African Institute for Aquatic Biodiversity (SAIAB))
- Description: Online version of original print edition of the Special Publication of the J.L.B. Smith Institute of Ichthyology; No. 22 , Plotosus nkunga sp. n., from the east coast of South Africa, possibly ranging as far north as Zanzibar, is most similar to Plotosus limbatus Valenciennes, from the coasts of India, Sri Lanka, Kenya and Aldabra. Plotosus nkunga differs most notably in having fewer total gill rakers on the anterior faces of the first two arches, 16 to 21 versus 20 to 25 first arch, 16 to 24 versus 23 to 27 second arch; in having modally one more precaudal vertebra and slight modal differences in number of ribs and branchiostegal rays; in the shapes of the mesethmoid and the parapophyses of the fourth and fifth centra of the anterior complex vertebra; in the length of the maxilla; and in certain body proportions. Descriptions, annotated synonymies and illustrations are given for both species. A key to the five known species of Plotosus is presented.
- Full Text:
- Date Issued: 1982-08
- Authors: Gomon, Janet R , Taylor, William Ralph , J.L.B. Smith Institute of Ichthyology
- Date: 1982-08
- Subjects: Catfishes
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/69871 , vital:29590 , Margaret Smith Library (South African Institute for Aquatic Biodiversity (SAIAB)) Periodicals Margaret Smith Library (South African Institute for Aquatic Biodiversity (SAIAB))
- Description: Online version of original print edition of the Special Publication of the J.L.B. Smith Institute of Ichthyology; No. 22 , Plotosus nkunga sp. n., from the east coast of South Africa, possibly ranging as far north as Zanzibar, is most similar to Plotosus limbatus Valenciennes, from the coasts of India, Sri Lanka, Kenya and Aldabra. Plotosus nkunga differs most notably in having fewer total gill rakers on the anterior faces of the first two arches, 16 to 21 versus 20 to 25 first arch, 16 to 24 versus 23 to 27 second arch; in having modally one more precaudal vertebra and slight modal differences in number of ribs and branchiostegal rays; in the shapes of the mesethmoid and the parapophyses of the fourth and fifth centra of the anterior complex vertebra; in the length of the maxilla; and in certain body proportions. Descriptions, annotated synonymies and illustrations are given for both species. A key to the five known species of Plotosus is presented.
- Full Text:
- Date Issued: 1982-08
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