Grains Research and Development Corporation, Canberra Australia Removing the hull improves the value of lupins for monogastrics and fish, but inclusion rates of kernel meal into pig and poultry diets is limited by the level of non-starch polysaccharide.
Compared to common carp, the culture of grass carp started much later. According to historical records, the culture of grass carp was closely related to the will of the current governor.
In the Tang Dynasty A. The royal family prohibited common carp to be sold and killed by the people. Therefore, grass carp was chosen by the farmers as a substitute for aquaculture together with silver carp, bighead and black carp; this was because the seed of these fish were easily available in the areas along the Yangtze River and the Pearl River.
The culture of grass carp remained relatively small in scale due to the dependence on the natural supply of seed. Success in induced breeding technology significantly promoted its culture. The fish has been introduced to more than 40 other countries; sometimes it is referred to as the white amur.
China is by far the major producer 3 tonnes in Main producer countries of Ctenopharyngodon idellus FAO Fishery Statistics, Habitat and biology Grass carp is a native Chinese freshwater fish with a broad distribution from the catchment area of the Pearl River in southern China to that of the Heilongjiang River in northern China.
It has been introduced to about 40 other countries and there have been limited reports about the natural populations occurring in those areas; for instance, a natural population exists in the Red River in Vietnam.
It inhabits lakes, rivers and reservoirs. It is a basically herbivorous fish that naturally feeds on certain aquatic weeds. Under culture conditions, grass carp can well accept artificial feed such as the by-products from grain processing, vegetable oil extraction meals, and pelleted feeds, in addition to aquatic weeds and terrestrial grasses.
Grass carp normally dwell in mid-lower layer of the water column. Comparatively, it prefers clear water and can move swiftly. It is a semi-migratory fish; the mature broodstock migrate to the upper reaches of major rivers to propagate.
Flowing water and changes in water level are essential environmental stimuli for natural spawning. The fish can reach sexual maturity under culture conditions, but cannot spawn naturally.
Hormone injection and environmental stimuli, such as flowing water are necessary for induced spawning in tanks. Gras carp grow rapidly and reach a maximum weight of 35 kg in the wild.
Production Production cycle of Ctenopharyngodon idellus Production systems Various production systems are currently used for the culture of grass carp the major ones include semi-intensive and intensive culture ponds, and pens and cages in open waters.
Seed supply At present artificial propagation is the major supply of seed for the culture of grass carp, although natural seeds are still available in some rivers of China.
Seed collected from the wild is mainly used for maintaining the genetic quality of the broodstock. Broodstocks used for artificial propagation are usually raised in captivity from seeds from the wild or from breeding stations where good natural stocks are maintained.
Hatchery production Well-matured breeders are released into the spawning tank round cement tank with diameter of m and water depth of around 2 m after being injected with inducing hormone usually LRH-A. Water circulation is maintained throughout the spawning period.
Eggs are transferred to hatching raceways or jars, either manually or by gravity. Hatching raceways which are round or ellipse-shaped structures are commonly used for large-scale production. The width of the raceways is normally 0. Screens are mounted on the inner wall for discharging water during the operation.
Water can be totally drained out through the outlet on the bottom.
Current flow is maintained during the hatching period to keep the eggs and larvae suspended in the water column. In India, dry or wet stripping methods are used for the seed production of grass carp.
Pituitary extract or synthetic agents such as ovaprim are used for induction John Stephen Kumar, pers. Nursery Earthen ponds usually 0. Ponds are chemically cleared, normally with quicklime, to eliminate all harmful organisms after totally drying. Green and animal manures can be used simultaneously but the quantity of each should be reduced accordingly.
Monoculture is practiced in the nursery stage, with a stocking density normally ranging between 1. The nursery operation usually takes weeks in China. Organic fertilization is carried out at frequencies and rates sufficient to maintain high pond fertility and therefore a good supply of natural food organisms especially zooplankton for the fish.Apr 24, · As North Korea's Kim Jong Un prepares for summits with South Korea and the US, Beijing fears Pyongyang is moving out of its orbit and striking out on its own.
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