5 research outputs found

    Potentials of short term and long term cryopreserved sperm of the African giant catfish (Clarias gariepinus Burchell, 1822) for aquaculture

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    To service the growing demand for male African giant catfish (Clarias gariepinus) broodstock for aquaculture in Nigeria, and to conserve valuable genetic resources, we improved both short-term (in deep freezer at -35°C) and long-term cryopreservation (in liquid nitrogen at -296°C) of catfish sperm. Catfish sperm cryopreserved at -35°C using three different types of cryodiluents composed of 10% methanol, glycerol or dimethylsulphoxide (DMSO) with 15% non-permeating cryoprotectant (skim milk) and 75%  phosphate-buffered saline (PBS) as extender was evaluated at day 1 to 28. Sperm motilities on thawing for the two cryodiluents that contained glycerol and DMSO were the same (p > 0.05) while those for the cryodiluent that contained methanol were significantly lower (p < 0.05). Sperm cryopreserved in DMSO and glycerol provided hatching at least 50% of catfish eggs. Liquid nitrogen (LN2) was with the same 3 cryoprotectants and one new extender based on glucose and skim milk (Ginzburg fish Ringer, GFR). Two thawing procedures were tried: 1) In the first trial, one set of sperm was frozen with different  cryodiluents with extenders in the freezer at -10°C and 2) Stored for up to 8 months in LN2. Sperm with up to eight months cryopreservation from the first trial when thawed at room temperature at 27°C for 15 min gave 0 - 6.25% fertilization rate (FR). The sperm stored for two months in the second trial when rapidly thawed at 35°C for 5 min gave better results. The FR of 94% was achieved with a cryodiluent of DMSO with 5% glucose solution and PBS when the cryopreserved sperm was thawed at 35°C. Also, DMSO in combination with PBS resulted in a higher FR than either glycerol or methanol. However, sperm cryopreserved with glycerol had the lowest motility rate in the 2 trials (p < 0.05). The use of  cryopreserved sperm did not significantly affect (p < 0.05) the survivability of the fry. The use of cryopreserved sperm of the African catfish for fry production will be especially beneficial in Nigeria where reliable sperm supply is a major bottleneck in the catfish aquaculture industry.Key words: Cryopreservation, sperm motility, Clarias gariepinus, African giant catfish

    Genetic characterization of Nigerian indigenous pig using polyacrilamide gel electrophoresis

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    The genetic structure of Nigerian indigenous pigs (NIP) and crossbred pigs were investigated using polyacrylamide gel electrophoresis. A total of 79 NIP blood samples were collected from three different locations within South-western Nigeria namely, Igbara Odo, Ekiti State (33 samples), Ogbooro, Oyo State (30 samples), and Institute of Agricultural Research and Training (IAR&T), Oyo State (16 samples). In addition, 41 crossbred pig blood samples were collected from the Teaching and Research Farm (T&R Farm), Obafemi Awolowo University, Ile-Ife. The blood serum samples obtained from the pigs were subjected to Sodium dodecyl sulphate (12%) SDS-PAGE gel electrophoresis. A total of 19 protein loci were scored for the NIP and 16 for crossbred samples. The SDS-PAGE electrophoretic profiles were analysed using PAST package (2005) to determine genetic similarity coefficients and construct phylogenetic dendrograms using Nei’s standard genetic distance. Ogbooro NIP samples showed a very high level of genetic similarity (91%) while IAR&T was 87% whereas Igbara Odo was 56%. The T&R Farm crossbred pigs showed 81%. The total local pig samples from the three locations gave a high genetic similarity coefficient of 84% confirming their genetic relatedness. The high genetic similarity observed in the indigenous pig samples in Ogbooro indicated a level of inbreeding of pig stocks in this locality which can be conserved as a genetic resource for breeding programmes for pure NIP in the future.Key words: Animal genetic resources, conservation, Nigeria indigenous pig, electrophoresi
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