November | December 2013

EXPERT TOPIC - CARP

The International magazine for the aquaculture feed industry

International Aquafeed is published six times a year by Perendale Publishers Ltd of the United Kingdom.All data is published in good faith, based on information received, and while every care is taken to prevent inaccuracies, the publishers accept no liability for any errors or omissions or for the consequences of action taken on the basis of information published. ©Copyright 2013 Perendale Publishers Ltd. All rights reserved. No part of this publication may be reproduced in any form or by any means without prior permission of the copyright owner. Printed by Perendale Publishers Ltd. ISSN: 1464-0058

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42 | INterNatIoNal AquAFeed | November-December 2013

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November-December 2013 | INterNatIoNal AquAFeed | 43

Welcome to Expert Topic. Each issue will take an in-depth look at a particular species and how its feed is managed.

CARPEXPERT TOPIC

1ChinaOverview of the present situation of carp farming in China

by Wang Xin, Song Zhigang, Yang Yong, Guangzhou Hinter Biotechnology, Guangdong, China

Carp is one of the main speciesof China's aquaculture industry,forming 13 percent of its farmedfish output. Because of their wide

adaptability,carpcanbefarmedinanextensivevarietyofregions.However,inrecentyearstheirquality in China has declined.With the blindpursuit of production volumes and backwardstepsinbreedingmanagementtechnology,manyproblemshaveappearedincarpaquaculture.

Biological characteristicsCommon carp belongs to the taxonomic group Osteichthyes of the animal kingdom, in the Cyprinidae family of the Cypriniformes subclass. Carp live at the bottom of water bodies, and tend to stir them up in foraging activity. Common carp can quickly adapt to the temperature and quality of water, and grow quickly at the same time (1 kg or more in a single year). Their breeding season is early April to early June, and reach sexual maturity after two years.Carp is a typically omnivorous fish, although they can be carnivorous. Their feeding mode

is deglutition. Carp fry mainly eat zooplankton, and later begin to eat benthos. When their body length reaches 7-17 cm, under natural conditions carp eat crustaceans, insect larvae, algae, plant tissue and so on. In the aquacul-ture industry farmers use compound feeds to provide their nutrition.

DistributionCommon carp grow quickly, have high output and a strong tolerance for envi-ronmental conditions, which means they can be cultivated widely from the north-ern provinces Heilongjiang, Liaoning, Tianjin, Hebei and Shanxi, to the southern provinces Yunnan, Sichuan and Guizhou. As mentioned above, carp is one of the main species for Chinese aquaculture, making up 13 percent of total production volume.

Common speciesThe most common carp species in China are Jian carp, Yellow River carp, red carp and German mirror carp. All have similar nutritional requirements although fish farmers must bear certain differences in mind. German mirror carp typically exhibit higher feed con-versation ratios than the Yellow River or Jian varities, and consequently tend to enjoy a faster growth rate (reaching 1.25 kg after a year, rather than 1 kg). However, the disease resistance of German mirror carp is poor, and require higher water quality to be successfully farmed. For these reasons, all three are viable aquacul-ture species, although German mirror carp enjoy higher and more stable prices in the marketplace.

2USAAquaculture carp threat to Great Lakes wildlife

Thoughapopularspeciesforfarmingintheirownright,carp’sbottom-dwellingbehaviour,toleranceofawiderangeofenvironmentalconditionsandomnivo-

rousfeedinghabitsalsomakesthemanattractivecandidateforintegratedaquaculturesystems.

Authorities in the Great Lakes region of the United States are now having to deal with the drawbacks of this hardiness, as Asian carp spe-cies originally imported to the southern states to control vegetation in aquaculture and waste-water treatment have been found spawning as far north as the Sandusky River in Ohio.

It is a well-established fact that the Mississippi River is infested with Asian carp, and one of those species, the grass carp, has made the jump to the tributary river of Lake Erie. Although vegetation-eating grass carp do significant damage to aquatic habitats, scientists are particularly worried about the prospect of bighead carp and silver carp joining them. They require similar spawning conditions to the species already in place, but as plankton feeders will out-compete and out-breed native fish.

US environmental official John Goss has called for the renewal of the administration’s US$200 mil-lion “aggressive strategy” to keep the Great Lakes free of the invasive species. Given the threat to the US$7 billion sports fishing industry and US$234 million commercial fishery in both the USA and Canada, it’s time to cut the carp.

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12

3

Optimum protein and lipid balance for C. auratusby Patrick Haughton, Hampshire Carp Hatcheries, UK

The growing season for first yearcyprinids is short in the UK.Typically the fish are spawned inlate April and May and the fry

are stocked out into ongrowing ponds inlate May to early June. For the first twoor threeweeks their diet is predominantlyzooplanktonbeforetheyareweanedontoacommercialdrydiet.

The fish farmer then has 16 weeks of temperatures above 15 °C (average 20 °C) to grow the stock to a market size of 5 to 50

g (5-14 cm) for the following spring's market demand. It is vitally important to maximise weight gain over this period. Protein efficiency ratios (PER) are less important as the ponds have a high capacity to process ammonia, with the long day lengths resulting in dense algae blooms and supersaturation of oxygen.

Most of the diets available to the freshwa-ter fish farmer in the UK are sold as optimal for carp or trout. By using a range of protein and lipid combinations, this trial intended to extend the understanding of the optimum balance for the intensive ongrowing of first year goldfish.

In collaboration with Coppens International, Hampshire Carp Hatcheries carried out an eight-week feed trial on goldfish (C. auratus) at Sparsholt College's National Aquatics Training Centre. The goldfish were fed four com-

mercial diets in triplicate so that their com-mercial performance could be measured.

The key parameters that were measured were growth, feed utilisation, economic per-formance and condition factor (shape).

Experimental materials and procedure

The trial was conducted in twelve aquari-ums (dimensions 90 x 30 x 30 cm) in a recirculation unit. Each aquarium maintained a

table 1:

Protien % lipid % Price euro/kg

Standard (S) 33% 6% 0.95

Basic select (BS) 34% 15% 1

Supreme 16 (S16) 46% 16% 1.19

Prime 18 (P18) 42% 18% 1.13

table 2:

Gross energy (MJ/kg)

Metabolisable energy (MJ/

kg)

relative metabolisable

eneergy

relative feed rate

Daily feed rate

Standard (S) 18.09 14.12 82.0% 1.22 3.66%

Basic select (BS) 20.26 16.57 96.2% 1.04 3.12%

Supreme 16 (S16) 21.14 17.01 98.7% 1.01 3.04%

Prime 18 (P18) 21.37 17.23 100% 1.00 3%

3

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November-December 2013 | INterNatIoNal AquAFeed | 45

flow of one litre per minute at 20 °C.

Each morning the aquariums were cleaned by siphoning any suspended solids and faeces. Water was replenished from a res-ervoir of standing dechlo-rinated water. Ammonia levels were routinely moni-tored throughout the trial.

Prior to the start of the trial, the goldfish were acclimatised to the aquari-ums for two weeks whilst being fed on a mainte-nance ration. At the start of the trial each aquarium was randomly stocked with 20 15 g (±0.5 g) goldfish. The mean values of the bulk weights of the fish on each diet were tested for differences using a one-way analysis of variance. There was no signifi-cant difference in bulk weights (p>0.05,f = 0.56,d.f.3,8).

The fish receiving the most energy-rich diet, Prime 18, were fed at 3 percent body weight a day. The other diets were fed iso-calorifically, so that all fish in the trial would have the same energy available (see Table 2).

The daily ration for each tank was pre-

weighed and divided into two roughly equal feeds, which were given at 8.30 a.m. and 4.30 p.m. The fish were fed just six days each week. On the seventh day the fish were bulk weighed and counted. New rations were calculated each week based on the new bulk weights.

At the start of the trial a random sample of 20 fish were weighed and measured for total length to calculate their condition factor. At the end of the trial a random sample of 20 fish

from each diet were weighed and measured for total length.

Results: diet utilisation and growth

During the course of the trial all of the feed was observed to be eaten. There were no mortalities and the water parameters were recorded the same for all aquariums.

The tanks ate between 650 g and 744 g of food over the trial. Feed conversion ratios

table 3:

Diet Protein, lipid% Foof fed (gr) FCr Per % Weight gain SGr %

Standard 33 & 6 744 (+/=56) 2.47 (+/-0.12) 1.23 (+/-0.06) 100%(+/-4.4) 1.24% (+/-0.04)

Basic select 34&15 662 (+/-58) 1.95 (+/-0.13) 1.21 (+/-0.09) 113%(+/-7) 1.41% (+/-0.06)

Supreme 16 46&16 650 (+/-13) 1.8 (+/-0.13) 1.21 (+/-0.07) 121%(+/-11.8) 1.41% (+/-0.09)

Prime 18 42&18 650 (+/-74) 1.72 (+/-0.09 1.39 (+/-0.07) 126%(+/-10.2) 1.46% (+/-0.08)

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(FCRs) varied from 1.72 to 2.47, PERs varied from 1.21 to 1.51, percentage weight gains var-ied from 100 % to 126 % and specific growth rates (SGRs) varied from 1.24 % to 1.46 %.

There were highly significant differences in the diets’ FCRs (p>0.001,f = 203,d.f.3,8). P18 had a very highly significantly lower FCR than the S diet (p<0.001). Basic Select (BS) and Supreme 16 (S16) had a highly signifi-cantly lower FCR than the Standard (S) diet (p<0.01). P18 had a highly significantly lower FCR than BS (p<0.01). S16 had a significantly lower FCR than BS (p<0.05).

Very highly significant differences were found in the PERs of the diets (p>0.001,f =85,d.f.3,8). BS had a highly significantly greater PER than S and S16 (p<0.01). BS had a signifi-cantly greater PER than P18 (p<0.05). P18 had a highly significantly greater PER than S and S16 (p<0.01).

The diets’ SGRs also displayed very highly significant differences (p>0.001,f =31.5,d.f.3,8). S16 and P18 had a highly significantly higher SGR than diet S (p<0.05). BS had a significantly higher SGR than diet S (p<0.05). P18 had a significantly higher SGR than diet BS (p<0.05).

EconomicsThe daily gross margin per diet varied from

0.174 per day for diet S to 0.209 for diet P18. The relative economic advantage of BS,

S16 and P18 to diet S were 11 percent, 16 percent and 20 percent respectively.

Carcass analysisThere was no significant difference between

the diets’ condition factors at the start or at the end of the trial (p>0.05,f=0.43, d.f.4,95).

ConclusionOver the eight-week trial the fish grew

on average by 115 percent. The Prime 18 diet with 42 percent protein and 18 percent lipids significantly outperformed the other diets in growth, FCR and economic efficiency. However, the Basic Select diet had a signifi-cantly better PER than all the other diets. This has implications for the production in a pond culture unit where there is a finite nitrification capacity.

There was no evidence of the extra growth generated by the high-lipid diets caus-

ing a change to the shape (condition factors) of the fish.

Further research for goldfish ongrow-ing could interpolate the optimum protein between 34 percent and 42 percent, and extrapolate the optimum lipid above 18 percent where growth is the predominant requirement.

In the UK during the autumn, winter and spring months when temperatures are below 15 °C there is negligible growth. Fish are fed a maintenance ration and it is important to utilize the protein as efficiently as possible, and minimize ammonia loading and its associ-ated stock management problems. Further research is needed to understand more fully the optimum protein and lipid levels during this period.

The author would like to thank Coppens International for their collaboration on this research.

About the authorDuring his 30-year lectureship in the fisheries department at Sparsholt College, UK, Pat Haughton has carried out nutritional trials for feed compa-nies and student dissertations.

He has retired as a lecturer but runs Hampshire Carp Hatcheries in partnership with Chris Seagrave. The hatchery is the UK's largest cyprinid fingerling producer, rearing eight spe-cies of cyprinids (chub, barbel, ide, tench, carp, goldfish, gudgeon and stickleback), and 20 colour varieties of these species. Their website is regu-larly updated to feature the farming operations and all areas of research and development.

table 4:

Food price £/kg

Cumulative FCr

Cost of food (£)/kg prod.

Gross margin (£)/kg

Final SGr%

Gross margin*

daily output

relative advantage

%

Standard 0.81 2.47 2.00 14.00 1.24% 0.174 0%

Basic select 0.85 1.95 1.66 14.34 1.35% 0.194 11%

Supreme 16 1 1.80 1.80 14.20 1.41% 0.201 16%

Prime 18 0.96 1.72 1.65 14.35 1.46% 0.209 20%

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