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COL, United States

An experiment was carried out in the research farm of An Giang University from January to April 2011.to compare integrated culture of Tilapia (Oreochomis niloticus) and Common carp (Ciprinus carpio) in an intensive indoor system with earthworms as feed, with an outdoor natural pond system, using biodigester effluent as fertilizer and duckweed as feed supplement. There were four treatments with three replicates in a completely randomized design with mixed stocking of Common carp and Tilapia (50: 50) at low and high densities (3 or 5 fish//m2 in the natural ponds and 60 or 100 fish/m3 in the intensive indoor system. In the outdoor system the fish were raised in natural ponds (4m2), seeded with duckweed and fertilized with biodigester effluent. In the indoor system, the fish were raised in PVC tanks (0.5m3) in an enclosed building and fed with earthworms. Growth rates at the higher stocking rate were lower for the Common carp in the pond system and tended to be lower for the Tilapia as compared with the low stocking rate. In the indoor system where the fish were fed ad libitum, the growth rates were less affected by stocking density. In the outdoor pond system growth rates were much higher for the Tilapia than for the Çommon carp. In contrast, in the intensive indoor system, there were no differences between the two species. The Tilapia gained from 0.95 to 1.32 g/day at high and low densities in the natural pond system but only 0.26 and 0.33 g/day in the intensive system. In the natural pond system the net fish yields were equivalent to 9 and 10 tonnes/ha/year for the low and high densities, respectively. Environmental pollution, as measured by concentrations of total ammonia-N and nitrite in the water, was some 50% greater in the intensive system. An economic analysis, on the basis of gross returns from the fish less the variable costs (fingerlings and feed), showed positive margins for all species/density combinations in the natural pond system compared with the negative margins for the intensive indoor system. Source

Phuong T.B.,Nong Lam University | Khang D.N.,Nong Lam University | Preston T.R.,TOSOLY
Livestock Research for Rural Development | Year: 2012

The objective of this study was to determine the effect of potassium nitrate versus urea, and of supplementary sulphur, on growth performance of cattle fed molasses and cassava foliage. Sixteen growing Laisind female cattle (Red Sindhi*local "Yellow" breed) with á range of initial live weight of 187-234kg were divided into two blocks according to live weight and within blocks were allocated at random to 8 treatments arranged as a 2*2*2 factorial with 2 replications. The factors were source of NPN (potassium nitrate: 6% of diet DM basis or urea: 1.8% of diet DM basis), level of added sulphur (0 or 0.8% S) and source of cassava foliage (fresh foliage or dried leaf meal). DM intake was not affected by NPN source, but was depressed by adding 0.8% sulphur and was lower for the treatment with fresh cassava foliage compared with leaf meal. After correcting the data by covariance for differences in initial live weight, growth rate was depressed by adding 0.8% sulphur to the diet but was not affected by source of NPN or source of cassava foliage. The ratio of methane to carbon dioxide was reduced by feeding potassium nitrate rather than urea and by fresh cassava foliage compared with cassava leaf meal. Source

Tu D.T.M.,Mekong University | Dong N.T.K.,Can Tho University | Preston T.R.,TOSOLY
Livestock Research for Rural Development | Year: 2012

Two experiments were conducted on a private farm in Binh Thuy District, Cantho City to study: (i) the yield and composition of duckweed cultivated with different levels of biodigester effluent; and (ii) the effect on duckweed composition of a "shock" treatment of transferring high quality duckweed to plain water containing no nutrients. In experiment 1, the treatments were 6 levels (0, 4, 8, 12, 16 and 20%) of biodigester effluent added to fresh water in plastic containers containing duckweed. The surface of water in each container was 0.4 m 2with 20 cm depth giving a volume of 60 liters. Duckweed was inoculated at a rate of 400 g/m 2. The yield of duckweed was measured over a period of 14 days by removing and weighing one third of the biomass every 48 h. There was a curvilinear response in yield, and in crude protein content of the duckweed, to level of effluent with maximum values for both at a ratio of 12% effluent and 88% water (72 mg N/liter). Duckweed from this treatment was then transferred to fresh water and the composition studied over 5 days. The content of starch increased and that of crude protein decreased with increasing time in the fresh water. It was concluded that yield and crude protein content of duckweed was optimized when the culture medium contained 12% biodigester effluent and 88% water. The "shock" treatment of transferring the best quality duckweed to nutrient-free fresh water led to decreases in crude protein and corresponding increases in starch. However, the effects were relatively small and unlikely to have significance from the points of view of duckweed as a feed for ducks or as a substrate for ethanol production. Source

An experiment was conducted at the Goat and Rabbit Research Centre to determine effects on feed intake, average daily gain (ADG), feed conversion ratio (FCR) and economic returns of New Zealand White rabbits raised on two feeding systems: sweet potato (Ipomoea batatas) vines with supplementation of paddy rice and Guinea grass plus commercial concentrate. There were 5 levels of supplement (paddy rice or concentrate): 0, 10, 20, 30 and 40 g/head/day. A total of 30 male growing rabbits at 6 weeks of age were equally divided into 2 main groups of 15 each to be fed on either of the two basal diets. Each of the two main groups was further divided into 5 sub-groups (treatments) of 3 rabbits each. The rabbits were housed and fed in individual cages. The experiment lasted 10 weeks following 7 days of adaptation. The system of sweet potato vines and paddy rice supported higher growth rates and better feed conversion than Guinea grass plus concentrate. In the Guinea grass-concentrates system the feed conversion became worse as the level of supplement increased; in contrast on the sweet potato vine-paddy rice system, feed conversion was the same irrespective of the level of supplementation. Source

Thu Hong N.T.,Angiang University | Preston T.R.,TOSOLY
Livestock Research for Rural Development | Year: 2013

Experiments were carried out at the farm of Angiang University from January to August 2011 to measure: (i) the effect of fertilization with biodigester effluent on biomass production of Tithonia diversifolia (Wild Sunflower); and (ii) the effect on intake and digestibility by growing goats of supplementing Tithonia diversifolia foliage with foliage from Sesbania sesban and/or Mimosa pigra. Biomass productivity of Tithonia was raised by 175% by increasing the level of fertilization with biodigester effluent from 20 to 60 kg N/ha. Feed DM intake was increased by from 11 to 23% and N retention by 30-32% when goats fed a basal diet of Tithonia were supplemented with foliage from either Mimosa pigra or Sesbania sesban, or the combination of both legume foliages. Source

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