Reuse of aquaculture wastewater treated in constructed wetlands

Water reuse in fish farming is a practice that has been spreading significantly, therefore requiring more efficient and vigorous treatment systems. The objective of this study was to evaluate the potential reuse of aquaculture wastewater after being treated in horizontal subsurface flow constructed wetlands (HSSF-CW). Three HSSF-CWs with dimensions of 1.0 m in width, 3.0 m in length, and 0.30 m in depth were evaluated. One HSSF-CW had stargrass (Cynodon nlemfuensis) cultivated; the other had cattail (Typha latifolia), and the third was used as a control, where there was no cultivation. The wastewater was provided from three Nile tilapia breeding tanks, which recirculated the entire system after going through the HSSF-CW. The following variables were determined every five days at the HSSF-CW influent and effluent: temperature, pH, turbidity, electrical conductivity, redox potential, dissolved oxygen, ammonium, and nitrate. The treatment in the HSSF-CW allowed the reuse of aquaculture wastewater as it provides water quality levels according to the recommendation for Nile tilapia breeding. Furthermore, the water quality parameters monitored in HSSF-CW effluent remained within limits established by CONAMA Resolution No. 357/2005 for aquaculture and fishing activity.

Comparativa multi e hiperespectral del pasto Cynodon nlemfuensis bajo condiciones tropicales y de pastoreo con ganado lechero

La información espectral ha sido utilizada ampliamente en el estudio de las condiciones nutricionales y en el desarrollo de diversos cultivos empleados en el ámbito agrícola, pero existe un vacío de investigación en especies forrajeras para condiciones tropicales. El presente estudio contempló la comparación de información multi e hiperespectral correspondientes al cultivo de pasto Estrella Africana (Cynodon nlemfuensis) dedicado a la alimentación de ganadería lechera usando espectroscopia de campo e información satelital de Sentinel-2. Se determinó que existe una heterogeneidad de la firma espectral del cultivo, debido al patrón aleatorio de alimentación por parte del ganado y la variación de las condiciones ambientales. Se generaron zonas con distintas alturas del cultivo, influyendo directamente en los valores de reflectancia, índice de área foliar e índices de vegetación. Se compararon los índices espectrales calculados con información de campo y satelital, obteniéndose valores de R2 de 0,725 para el caso del NDVI y de 0,446 para el SAVI. La presente investigación es de gran relevancia ya que sienta la línea base del uso de información espectral para el estudio de pastos dedicados a la alimentación de ganado lechero a partir de sensores remotos y espectrorradiometría de campo.

GRAIN REPLACEMENT VALUE OF CASSAVA AND SWEET POTATO FOR GROWING LAMBS

TWENTY-FOUR rams of the West African Dwarf X Yankasa crosses, 6 to 7 months old, ranging in liveweight from 11 to 14 kg were randomly alloted to maize, sweet potato and cassava based rations. These rations constituted the concentrates which were fed as supplement to Cynodon nlemfuensis. Three rams from each treatment were slaughtered at the end of 30 day and another set of three rams each were slaughtered on the dietary treatments and other nine, 140 day later Replacement of the conventional maize grains by dried milled cassava and potato tubers in sheep diet did not dentess the growth rate, dressing-out percentages, major cuts, quality of the organs. and the general performances of the animals. Sweet potato based diet however improved the feed per gain estimate, the fats and protein content of the carcass. The highest proportion of lean ment was produced by the animals fed cassava based diet.

GRAIN REPLACEMENT VALUE OF CASSAVA AND SWEET POTATOES IN RATIONS FOR GROWING LAMBS.

27 LAMBS made up of 24 West African Dwarf (WAD)X Yankasa crosses aged 6 to 7 months old of 11 to 14kg weight and 3 WAD wether sheep, about 3 years old and weighing 34 to 39kg were used in this experiment designed to evaluate the maize replacement value of sweet potato and cassava tubers in sheep diet through energy and protein utilization. Each of the wether sheep carried permanent rumen cannula. The results showed that the maize, sweet potato and cassava based concentrates fed as supplement to grass (Cynodon nlemfuensis) improved the digestibilities of crude fibre, crude protein, organic matter, NFE and N-balance. The treatment effect was significant (P<0.05) with the highest coefficients and N-retention values recorded for Animals fed sweet potato based concentrate. The ruminal VFA's production, ammonia and blood urea levels followed the same trend for all the three energy sources but the treatment effect was not significant. All the parameters so obtained on energy and protein utilization, however, indicated that the dried milled sweet potato and cassava tubers can successfully replace maize grains in sheep diet.

THE NUTRITIVE VALUE OF HAY FROM FOUR GRASS SPECIES CUT AT THREE STAGES OF GROWTH AT IBADAN

Four grass species namely: Cynodon nlemfuensis var robustus (M); Pennisetum purpureum Schum (N); Cynodon nlemfuensis var nlemfuensis (P); and Panicum maximum Jacq. (Q), each between the 4th and 5th, 6th and 7th, and 8th and 9th week of regrowth, was cut in the fourth and fifth years of grazing for hay (i. e. in 1972 and 1973). Digestion trials with West African dwarf sheep showed that there were significant differences in the extent to which the dry matter of the different grass species was digested (P 0.001) and among the stages of growth (P 0.01). The differences between animals within and between treatments and the interactions between treatments and periods of cutting were statistically not significant. The differences among treatment means indicated that treatment Q (68.5 ± 2.73%) was digested better than treatment M (54.9 ± 7.18%, P 0.001), and treatments N and P (60.3 ± 5.37% and 58.7 ± 5.30% P 0.01) respectively. The digestibility of crude protein was generally low in each of the grass specie studied. This is probably a reflection of the low crude protein content of the grass hays which was below 9 percent of dry matter. It ranged from approximately 27.3 percent in treatment N for the 6th week regrowth hay to 51.9 percent in treatment Q for the hay harvested in the 8th week of regrowth. The differences among treatments, stage of maturity, and the interactions between treatments and stage of cutting were not statistically significant. Significant differences between treatments were observed in the digestion of the energy content of the feeds (P 0.001). Treatments N and Q were better digested than M and P (P 0.05). Expressed on metabolic size basis, the intakes of dry matter, crude protein, and energy showed significant differences between treatments and between ages at harvest. The intakes of dry matter in treatments Q, M, and P were significantly higher (P 0.05) than treatment N while there was more dry matter taken from the 4th and 8th week hays than from the hays made from the species harvested in the 6th week of regrowth (P 0.01). More crude protein was consumed per kg0.75 in treatments M, P and Q than in treatment N (P 0.01), and in treatment M than Q (P 0.05). There were higher protein intakes from hays made in the 4th and 8th than those made in 6th week of regrowth (P 0.05). Treatment Q supplied more energy per kgl. 75 than treatments M, P and N (P 0.05), while more energy was consumed per kilogramme of metabolic size in treatment P than in treatment N (P 0.05). Nutritive Value of Hay. The intake of digestible crude protein was relatively low and this probably accounted for the losses in the liveweight of the experimental animals. The results of the experiment are suggestive of the need for supplementary protein feed during the dry season if animals are to make any liveweight gains.

Feed Intake and Nutrient Utilization by Three Breeds of Cattle

Two feeding and digestibility trials were carried out to investigate the effects of groundnut cake (GNC) supplementation on feed intake, DM digestibility, nutrient utilization and liveweight gain of three breeds of cattle fed on all-roughage rations (hay and fresh grass) of Cynodon nlemfuensis var robustus. The results showed a decrease in mean DM intake of the basal ration by approximately 13.14%; 1.9% and 6.4% and an increase in total dry matter intake (basal + GNC supplement) of approximately 0.42%), 11.56% and 11.04% for the indigenous, crosses and exotic animals respectively. The results also showed non-significent increases in the apparent digestibilities of the nutrients. Both the total Digestible Nutrients (TDN) kg/W0.75 and Metabolizable Energy (ME) Kcal/W0.75 intake by the three breeds of cattle were increased with supplementation and mean daily liveweight increased by 18.92%, 13.15% and 16.27% respectively.

In Vivo and in Vitro Digestibility of Four Tropical Grass Species Growing at Ibadan

Digestibility trials carried out in November and December, 1971 with twelve West African dwarf ram fed Cynodon nlemfuensis var. robustus; Cynodon nlemfuensis var. nlemfuensis: Pennisetum purpureum Schum; and Panieum maximum, Jacq, each at 4 weeks and 8 weeks of regrowth showed that the differences that may exist between methods and among treatments in organic matter digestibility were not statistically significant (P> 0.05). Similarly, analysis showed no significant differences among animals or between periods within each treatment except for Cynodon nlemfuensis var. nlemfuensis where differences between period were significant (P <0.01). There were high positive correlations between in vitro and in vivo organic matter digestibilities as well as between in vitro organic matter digestibility and Total Digestible Nutrients (TDN). It is suggested that in vitro organic matter digestibility can be used to predict the digestibility of these tropical grass species and, may be, other similar grass species.

The Yield, Intake and Animal Production of Four Tropical Grass Species Grown at Ibadan

The yield, intake and animal production of four grass species namely: Cynodon nlemfuensis var. robustus, Pennisetum purpureum Schum; Cynodon nlemfuensis var nlemfuensis (Ib8) and Panicum Maximum Jacq., designated as treatments M, N, P, and respectively, were studied over a period of 1,226 days. Each treatment was grazed at three stages of growth - at four, six and eight week intervals. Total dry matter yields for the experimental period ranged from approximately 22 tons for treatment N grazed at intervals of four weeks to 65 tons for treatment Q grazed at eight week intervals. The mean daily dry matter yield varied between approximately 18 kg for treatment N to 53 kg for treatment Q grazed at four and eight week intervals respectively. With the exception of treatment N, dry matter intake by sheep per kg of metabolic size per day decreased with increased maturity and ranged from 43 kg in treatment N to 86 kg in treatment P grazed every four weeks. Treatment means of liveweight increases of grazing White Fulani (Zebu) steers were 392 g, 360 g, 337 g and 226 g per head per day for treatments Q, N,P and M respectively. Though the protein content of the pastures was high enough even in the dry season to maintain the grazing animals, dry matter production and intake were usually very low.

A NOTE ON CORN COBS IN SHEEP DIET

Twelve West African dwarf lambs 11 to 15 months of age and weighing 7.0 to 10.0 kg were randomized into three groups. Each group was fed diets containing zero, twenty-five and fifty percent corn cobs as replacer for hay (Cynodon nlemfuensis) in maize and groundnut cake-based media. Two mates from each treatment group were later placed in individual metabolic cages for digestibility experiments. Results showed that dry matter (DM) intake, weight gain, efficiency of fed utilization and nutrient digestibility values were similar for animals on rations A (zero corn cobs, 50% hay) and B (25% corn cobs, 25% hay) which were higher than values obtained for animals on ration C (50% corn cobs, zero hay). Results obtained also suggested that 25% ground corn cobs could be successfully incorporated into the diets of West African dwarf sheep for optimal utilization.

Studies on Comparative Utilization of Urea and Groundnut Cake Rations by West African Dwarf Goats

Twelve West African dwarf castrated goats, 6-8 months old and 7 to 15 kg liveweight, were used. Two sources of N, urea and groundnut cake, were used at three levels of crude protein (N x 6.25), viz., 10, 17 and 24%, in cassava flour-based rations. These rations were then used as supplements to dry, poor quality Cynodon nlemfuensis forage. Six animals, two on each level of protein were maintained on the urea-based rations in 3x3 Latin Square Design while the other six animals were similarly maintained on the groundnut cake-based rations. Each experiment consisted of three trials and each trial lasted three weeks. During these periods, liveweight changes, daily intake of the forage and of the concentrates were recorded. N-balance studies were also carried out at the end of the series of these experiments. The results indicated that the urea-fed goats tended to grow faster than those goats fed on the groundnut cake-based rations with the overall mean live weight gains of 35.7 and 31.4 g per day respectively although the differences were not significant (P>0.05) respectively. The former required daily 0.17g DCP per Wkg0.734 for maintenance; similarly the latter required 0.26g DCP per Wkg0.734 per g live weight gain and 1.43 g DCP per Wkg0.734 for maintenance. The N-balance studies also showed better utilization of the N content of urea than that of the groundnut cake, with the overall mean N-balance values of 6.15 and 5.54 g/day.