This study was conducted to determine the effects of oxygen supplementation and nitrogen supersaturation on the fecundity and performance of Lewis Lake strain lake trout, Salvelinus namaycush, brood stock. Performance of brood fish held in water supersaturated with oxygen was compared to that of controls raised at or below 100% saturation for 334 days. Incoming water averaged 78.4% saturation in the morning; the addition of oxygen increased saturation to 104.6%. As a result, average morning nitrogen saturation was reduced from 105.7% to 100.9%. In oxygen-supplemented water, peak daily oxygen saturation averged 129.0% in the afternoon. At this saturation level, average nitrogen gas was reduced to 98.4% saturation. Total gas pressure never exceeded 109.1% with oxygen supplementation; however, nitrogen supersaturation reached 110% in raceways with no oxygen supplementation. Weight gain, feed conversion, egg survival, egg size, and number of eggs per female were not affected by increasing oxygen saturation. 相似文献
Summary Recent collecting activities have shown that Cuba is rich in plant genetic resources of lima beans. Seed characters of 173 Cuban accessions were measured. Principal component analysis and discriminant factor analysis were used to compare the accessions, which could be classified into seven groups: wild, weed, Potato, Potato-Sieva, Sieva, Sieva-Big Lima, Big Lima. The Sieva type is the principal group of Cuba. It has arrived to Cuba in pre-Columbian times via the Antilles arc. After the Conquest the Potato type was introduced from Central America. Introgressive hybridization with the Sieva group led to the intermediate Potato-Sieva type, whereas the Sieva-Big Lima type resulted from selection toward larger seeds within the Sieva group. The Big Lima type was introduced relatively late. Cuba occupies a key position in the distribution of Lima beans within the Americas and also to the Old World. 相似文献