Ammonia toxicity and tolerance in the brain of the African sharptooth catfish, Clarias gariepinus

Cost-effectiveness, food utilization and proximate composition of Clarias gariepinus fingerlings fed locally formulated (sinking) and commercial (floating) diets in tarpaulin tanks were observed for 56 days. Ninety (90) C. gariepinus fingerlings with initial mean weight (72.99 g ± 3.09) per treatment were observed during the period with three replicates at a stocking density of 15 fish per m2. The fish were fed 5% body weight three times daily. Results showed that C. gariepinus fingerlings fed floating diet had significantly lower (p<0.05) feed conversion ratio (0.83 ± 0.03) than sinking diet (3.23 ± 0.40). Protein efficiency ratio was significantly (p<0.05) higher in fish fed commercial diet (2.69 ± 0.09) than locally formulated (0.80 ± 0.11). Specific growth rate was significantly (p<0.05) higher in floating (3.29 ± 0.07) than sinking diet (0.97 ± 0.20). Incidence cost was lower (₦1,989.65) in fish fed commercial diet than locally formulated (₦3,819.63). The profit index was higher in C. gariepinus fed floating diet (0.74) than sinking (0.19). From these findings, floating (commercial) feed is recommended for feeding C. gariepinus fingerlings since it showed better food utilization, better proximate composition of the carcass, higher profit index and consequently lower incidence cost.Keywords: Clarias gariepinus, cost-effectiveness, sinking feed, floating feed, incidence cost.

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Ammonia toxicity and cerebral oxidative metabolism

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1961.200.3.420 ◽

1961 ◽

Vol 200 (3) ◽

pp. 420-424 ◽

Cited By ~ 91

Author(s):

Guy M. McKhann ◽

Donald B. Tower

Keyword(s):

Oxidative Metabolism ◽

Incubation Medium ◽

Lactic Acid Production ◽

Ammonia Toxicity ◽

Thiamine Pyrophosphate ◽

Oxidative Decarboxylation ◽

Cortex Slices ◽

The Brain ◽

Cat Cerebral Cortex

Effects of NH4Cl on oxidative metabolism of cat cerebral cortex slices and mitochondria incubated in vitro were studied. In slices, addition of 10 mm NH4Cl to the incubation medium resulted in significant (16%) reduction of O2 uptake, doubling of lactic acid production and marked increase of glucose utilization compared to control slices. Mitochondria showed a 30–40% decrease of O2 consumption in the presence of 15 mm NH4Cl when pyruvate or α-ketoglutarate were substrates, but little if any difference from controls with succinate, glutamic acid or γ-aminobutyric acid as substrates. Pyruvate utilization by ammonia-treated mitochondria was inhibited to the same degree as O2 consumption and was not increased by supplementing the incubation medium with excess succinate. Additions of α-lipoic acid, thiamine pyrophosphate or DPN to such preparations failed to reverse the NH4Cl effect. Satisfactory P/O ratios were obtained for all mitochondrial preparations. It is concluded that a primary toxic effect of ammonia on the brain may be direct interference with oxidative decarboxylation of pyruvic and α-ketoglutaric acids.

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