The use of cold shock in inducing triploidy in African mud catfish (Clarias gariepinus)

study was conducted to induce triploidy in African mud catfish Clarias gariepinus using cold shock. The fertilized eggs were exposed at one temperature regime of 0°C with varied shock treatments of 0, 15, 25 and 30 min. Some 3 min after fertilization, the success of triploidy was determined by the presence or absence of bent trunk in the fry as reported by (Aluko et al., 1997). The shock duration of 25 min at 0°C gave the best result of 55% hatch with survival at the end of the exposure regime of 43.5%. Shock exposure of 30 min gave 30% hatch while 15 and 20 min exposure were poor at 15% hatch

Age And Growth Of An Ecotype Cichlid “Wesafu” In Epe Lagoon, Lagos, Nigeria

A sample of 150 specimens of “Wesafu” in the size range of 78mm and 414mm were collected from Epe Lagoon. The period of collection spanned August to November 2003 and April to Ma y 2004 for age and growth pattern determination of this Ecotype Cichlid of Epe Lagoon. 900 scales were examined and another 232 rejected/discarded because they were regenerated or irregular. Growth rings were counted and scale radii measured. The study showed a mean range of observed lengths to be 181±12.5; 265 ± 11.6; 305 ± 1.6 and 337 ± 3.4 for the successive years of growth. The most rapid growth in length occurred during the first year in life [181mm, (+1yr.)] thereafter decrease to only 32mm in the fourth year (+4yr.). The T-test suggests that there was no significant difference between mean back-calculated body length of male and female samples for age 1+ to 3+. However, in the age group 4+, male specimens were significantly larger than the female. The fact that the fish is highly demanded and commands premium price may result in over exploitation. This explain why only 5 of the 150 specimens were of the age 4+, representing only 3.33% of total specimens which raises serious conservation question and the need for domestication and aquaculture of this highly valued fish in Lagos, Nigeria. Keywords: Age and Growth, Ecotype Cichlid, Epe-Lagoon, NigeriaGlobal Journal of Agricultural Sciences Vol. 7 (1) 2008: pp. 105-10

Evaluation of different hydrocolloids to improve dough rheological properties and bread quality of potato–wheat flour

peer reviewedThe aim of study was to investigate the effect of hydroxylpropylmethylcellulose (HPMC), arabic gum (AG), konjac glucomannan (KG) and apple pectin (AP) at 2% (w/w, potato-wheat flour basis) on the potato-wheat dough (the mass ratio was 1:1) rheological, fermentation properties and its bread quality. The tan δ of potato-wheat dough was significantly increased by adding HPMC compared to those of without adding hydrocolloids (from 0.337 to 0.425), which was close to wheat dough (0.531). Moreover, the dough height during fermentation process was significantly improved by adding hydrocolloids, with the order of HPMC (23.1mm) > AP (19.3mm) > AG (18.6mm) > KG (13.6mm). In addition, the potato-wheat protein bands of potato-wheat dough turned pale by adding hydrocolloids, suggesting higher molecular weight aggregation formed between proteins-hydrocolloids or proteins-proteins after fermentation process. Furthermore, HPMC significantly increased specific volume (from 1.45 to 2.22 ml/g), and hydrocolloids restrained the starch retrogradation of potato-wheat breads.Research Project: Research and Demonstration of Key Technology System of Potato Staple Food (201503001-2