How To Determine Daily Feeding Amount For Animals

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8. IF I DECIDE TO FEED MY ANIMALS, HOW MUCH FEED WILL THEY NEED? HOW Practice I FEED AND HOW Ofttimes?

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8.1 Feeding Charge per unit
viii.2 Feeding Frequency and Other Factors
viii.iii Biomass Assessment

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8.i Feeding Rate

This topic is vitally important for efficient aquaculture. Underfeeding can result in loss of production. Overfeeding will cause a wastage of expensive feed and is additionally a potential crusade of water pollution, a condition resulting in loss of animals or requiring expensive corrective measures. Thus, both overfeeding and underfeeding take serious economic consequences which touch the viability of the farm.

Sometimes you lot may read a vague instruction, like 'feed five% of biomass per day' for a dry feed. This might exist applied throughout the growing wheel. This would almost certainly outcome in most starvation in the early stages and gross overfeeding and water quality problems later. Feeding rates should non stay steady throughout the whole of the growing cycle to market size. They must exist modified according to the size and age of the fish or shrimp, and to the h2o conditions.

The quantity of feed to exist given to a pond or muzzle each day should normally be based on a percentage of the biomass present (total weight of animals). Thus, if a pond contains 10 000 fish weighing 10 thousand on average and the recommended feeding rate (see afterwards) is stated to be seven% per day, the amount of feed to exist given daily is:

The per centum of biomass to be fed is not a fixed amount. It should decrease as the animals abound, to reverberate their decreasing metabolic rate. Thus the ratio of weight of feed per 24-hour interval to animal weight (biomass) is high at the get-go of the growing period and lower towards the time when the animals reach marketable size.

Applying a feeding rate accurately depends on an accurate gauge of average animal weight and of the numbers of animals in the product unit (pond, cage, etc.) (survival). Average weight can exist obtained directly from weighing samples or by measuring the length of the animals, where an accurate length/weight relationship has been established. Comments on these topics are contained in section viii.iii. Authentic record keeping is essential non but to aid efficient feeding now just also to enable you to examine the outcome of past actions and to help you predict the result of planned actions during the side by side growing wheel.

Feeding tables have been constructed for various aquatic species. Many are to be constitute in the references given in 'further reading' at the end of this section; manufacturers of compound feeds always requite a feeding guide for their products. Examples of feeding tables are provided in Appendix 13. The tables for those species, such as trout, which are reared under highly intensive conditions tend to be more than elaborate and reliable because they are based on many decades of accurate observation and measurement. They ordinarily specify feed blazon and size also as the daily feeding rate. Similarly elaborate tables will become bachelor for other species every bit more becomes known most the most efficient ways to present their feed. Meanwhile simple feeding guides for some species are bachelor (Appendix XIII).

It is emphasized that the feeding rates given in tables must non be applied without reference to other factors. Feed should be reduced in quantity or omitted during times of low temperature and, based on operational experience in a specific location and environment, increased when growth rates are predicted to be highest. Daily feeding rates must likewise be based on your observation of the animals during feeding. At this time feeding activeness, water quality (color), presence of old feed, etc., must be assessed. All feeding tables are merely a guide which, if practical with careful judgement, will markedly amend economic viability. All the same, if applied rigourously without complementary cess of conditions, they can result in disaster.

Equally stated before, feeding rates should be decreased as the animals grow. Feeding a steady percentage of biomass throughout the growing cycle ordinarily results in underfeeding when the animals are small-scale, depressing growth and survival rates, and overfeeding when the animals are larger. The total effect is depressed growth rate, poor survival, and poor AFCR. The more frequently feeding rates are adjusted, the more efficiently will feed be utilized. Ideally they should be adjusted daily but this would require too much newspaper piece of work and would misfile those who do the feeding. Also, it is only possible to adjust the feeding rate accurately when the biomass tin can be estimated by measurement or when it can be accurately predicted from by experience. This is where authentic, long-term records are so important.

In practise, feeding rates are adapted weekly or twice-monthly for salmonids and catfish, based on estimates of biomass, together with a cognition of environmental conditions (mainly temperature). Feeding tables for other species are now less refined and feeding rates are adjusted less frequently. For example, using a feeding table given in Appendix XIII for carp, the amount of feed to be given daily (at xx-23° C) begins at ix% for animals of less than 5 g in size. It changes to 7% for animals of 5-20 g and to 6% for those of 20-50 m boilerplate weight. Further reductions, to 5%, iv%, and 3%, respectively for animals weighing 50-100 yard, 100-300 1000, and 300-i 000 g are recommended in that tabular array. Obviously, changes in feeding charge per unit will exist less frequent when this blazon of table is used, than is possible with the more detailed tables, such as are given in Appendix 13 for salmonids. In practice, more frequent adjustments tin can be made to feeding rates even when simple feeding tables are used. In the example just mentioned, feeding rates at 20-23° C could be adjusted more frequently in the following mode:

Animal Size (yard)	% of Biomass to be Fed per Day
	Recommended in Table	Adapted Actual Rate
five	7	7.0
10		vi.vii
15		6.3
twenty	half dozen	half dozen.0
xxx		5.vii
40		5.3
50
	five	v.0
lx		4.8
70		4.6
80		4.iv
xc		iv.2
100		4.0

Increment in growth can be measured by length or by weight. With some species, notably salmonids, so much is known virtually their characteristics that unproblematic methods of predicting growth charge per unit nether each environmental condition accept been derived which enable more complex feeding schedules to be planned 1 or two months ahead. The ability to do this, peculiarly for a big subcontract with many different tanks and creature batches of differing sizes, is essential for forward planning of feed purchases, storage requirements, cash flow, etc.

The following example, adapted from Piper et al., (1982) is given of the way in which this type of feed table tin can exist used:

Salmonids, when reared at constant temperature, increase their length at a constant rate for the offset one ½ years of life. The weight of fish at each given length is besides known. For a certain temperature the corporeality of daily feed needed can exist calculated from the formula:

where:

FCR = the amount of feed necessary to produce a unit of measurement of animal weight increase (e.chiliad., ane.2 kg feed to produce an increase of weight of ane kg is equivalent to an FCR of 1.two).

A = the daily increase in length in centimetres

B = the length of the fish in centimetres at the present time

To calculate 'A' in the above formula, an boilerplate monthly growth in centimetres is established from the records of previous years on the farm at the same temperature. This is divided by the number of days in the month to obtain a value for 'A'. The value of FCR is also extracted from previous experience, recorded in the farm data, of animals of the same size category reared with the same type of feed at the same temperature.

This equation enables feeding rates to be predicted in advance and adjusted oft even when animals are non sampled and measured so often. Information technology is emphasized that such a sophisticated organization is but possible where there have been many years of feel in rearing the aforementioned species and where long-term record keeping has been faithfully attended to. An case of the calculation involved is given below:

Suppose, on thirteen April, there are 200 000 fish present in the pond. Their feeding rate was concluding determined on 1 April, when the fish were 9.07/kg per 1 000 fish (or 1.45 cm in length) 1/. Nosotros wish to adjust the feeding charge per unit over again now, knowing from past records that at this operating temperature, the average length increase per day (A) will be 0.0075 cm during Apr and the expected FCR is 1.2.

The new feeding rate is so calculated:

Length, 1 April:	i.45 cm (ix.07 kg/1 000) ane /
Plus growth, 13 days x 0.0075 cm (A):	0.0975 cm
= Calculated length today (B), thirteen April:	1.5475 (11.03 kg/1000) i/

i/ From tables of length/weight relationship

Applying the formula, the amount of feed to be given, as a pct of biomass, is:

Thus the weight of feed to apply is:

As the daily increase in length in abiding, and the length/weight relationship is known, this formula can be used to calculate new daily feeding rates oft even though actual measurements of body length are infrequent.

The above instance assumes 100% survival. In do this is extremely rare so the biomass figure must take into account estimates of creature population besides as size. It is foolish to feed for 200 000 fish if at that place are, for case, simply 160 000 left. (see section 8.three).

Very small fish and shrimp fry are generally fed to excess. Fry should exist fed to satiation several times per day. Feeding rates for fry can be as high as 50% of biomass/solar day for catfish and 100-200% of biomass/solar day for very young shrimp or prawn postlarvae. Feeding at such high rates, especially if stocking rates are also high, places a strain on water quality which must be relieved by greater water substitution, the removal of waste feed and detritus, etc. The extra trouble and expense involved in such treatments is more recompensed by the production of healthy, fast-growing fry with expert survival rates.

Feeding rates for aqueduct catfish in the U.S.A. boilerplate 3-5% of body weight per day throughout the flavor (come across tables in Appendix Thirteen) because of seasonally changing water temperatures, except when the animals are shut to market place size. Feeding rate does not, in this instance, start high and decrease gradually equally it would do if the whole of the growing wheel were conducted at almost constant temperature level (as it would for fish grown in tropical zones). An case of feeding rates for channel catfish kept at abiding temperatures is also given in Appendix XIII for comparison.

Feeding rate tables for trout, salmon, channel catfish, common carp, tilapia and marine shrimp are provided in Appendix XIII.

Many prawn farmers, for instance in Thai freshwater prawn civilization, feed 'to need' rather than according to a feeding rate table. Daily feeding rate is adjusted according to how much of the previous day's feed is consumed. This is reasonably effective where the farmer is experienced especially where prawns, rather than fish, are being reared. Fish tend to eat more than than is really necessary, resulting in poor FCR, if likewise much feed is presented. Phytoplankton density, measured with a Secchi deejay or by hand, which obscures at 25 cm or less, is besides used to detect overfeeding and equally a means of decision-making feeding rate. For a freshwater prawn batch-civilization pond, stocked at 5 animals per square metre, the feeding rate starts at about half-dozen.25 kg/ha/twenty-four hour period, rising to nigh 37.5 kg/ha/twenty-four hour period at harvest time (New and Singholka, 1982). The final feeding rate is equivalent to about three% of biomass per day.

8.2 Feeding Frequency and Other Factors

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8.2.ane Salmon and Trout
eight.2.2 Catfish
8.2.3 Tilapia
8.2.4 Carp
8.ii.5 Other Fish Species
8.2.6 Shrimp and Prawns

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The most effective method of feeding with respect to location, time of day and frequency varies from species to species. Its cost effectiveness depends also on other factors such as the availability of feeding labour or automatic feeders, size of swimming or tank, toll of labour, and the personal preference of the farm manager, based on observations and results. In this department of the manual a brief review of information most each of the major groups of cultured aquaculture species dealt with here is presented.

A number of bones rules, suggested by Piper et al., (1982) are summarized commencement:

a) for optimum growth and feed conversion, each feed should ideally be only i% of the body weight. Thus, if 5% of biomass per twenty-four hours is being fed, there should exist v feeds per mean solar day

b) survival rate is not significantly affected by feeding frequency once the initial feeding stage of the animals has been passed

c) frequent feeding reduces starvation and stunting of modest fish; thus the grouping has ameliorate uniformity

d) infrequent feeding results in feed wastage, poor FCR, water quality issues, and the leaching out of water soluble nutrients

e) dry feeds should be distributed more frequently than moist feeds

f) 90% of the feed (for fish) should be consumed within xv minutes or less of the feeding time.

In narrow or small ponds for fish, feed should exist spread evenly around the perimeter. For larger ponds, other methods accept to be used to requite adequate distribution, especially for species which are territorial in nature. These methods include feeding from a boat, feed blowers towed by a tractor, and (in the U.s.a.A.) distribution by aeroplane for very large ponds. Boats are, of course, essential for the feeding of moored cages which are not connected to the shore by a walk-way. Information on feeding devices is given in Appendix XIV.

Returning to the subject of feeding frequency, the following sub-sections summarize information on a species by species footing.

8.2.1 Salmon and Trout

In common with other very immature fry of fish and shrimp, very frequent feeding is nearly effective for young salmonids. For swim-upwards fry of salmonids the daily feed ration is split up into very pocket-size quantities fed as often as 20-24 times per day, either manually or automatically. Sometimes a 24-60 minutes lighting regime is used for the first few days to encourage the fry to take dry feed. Feeding frequency is gradually reduced to one-3 times per solar day as the fish grow. Rainbow trout start to take food about twenty-one days later on hatching when reared at 10° C. Almost hatcheries feed at ½ to ane hourly intervals during an 8-60 minutes day, reducing this to three times per day. After the fish are nearly 5 inches long (23 g) feeding frequency is reduced to twice per solar day. Brood fish are fed only once per mean solar day. Feeding frequencies quoted by Piper et al., (1982) for coho salmon, autumn chinook salmon and rainbow trout are given in Table 22.

Salmonids are frequently reared in tanks or cages so feed distribution is not a problem. Many unlike types of automated feeders are utilized, some of which are mentioned in Appendix XIV.

Table 22 Suggested Feeding Frequencies for Salmonids

Species		Fish Size (g)
		0.3	0.45	0.61	0.91	one.82	3.6	6.one	15.1	>45.1
		No. of Feeding Times Per Day
Coho salmon		ix	eight	7	6	5	3	three
Autumn
	Chinook salmon	8	viii	8	6	5	iv	3
Rainbow trout		8	8	6	vi	v	4	iv	3	ii

Source: Piper et al., 1982

Salmonids tend to feed to satiation and and then do not consume again until most of the meal has left the tum. Once by the fry stage therefore, a feeding frequency of 1 or 2 times per day is sufficient.

viii.two.two Catfish

The data presented here refers to channel catfish; it is reasonable to assume that it is applicable to other species of catfish.

Channel catfish fry begin to feed 5-10 days subsequently hatching, when the yolk sack reserves are used upwards. Every bit with salmonids, swim-upwards fry are all-time fed many times per day. One commercial feed manufacturer, whose feeding table is reproduced in Appendix XIII, recommends 8-10 feeds per solar day, reducing quickly to 6 per day by the time the fish are about 2.five cm long. Feeding frequency is farther reduced to 3 times per day when the fish reach vii.vi cm in length. Juvenile catfish grow all-time with two feeds per day, ane at mid-morning and one belatedly in the afternoon, seven days per week.

Feeding frequency in ponds depends on h2o temperature. At 13-29 C, feeding 6-7 times per calendar week is recommended. At times of particularly high or depression temperatures, less frequent (4 or 5 times per week) feeding is suggested. Feeding 6, instead of seven days per week is said to encourage the fish to consume whatever surplus feed in the pond and lessen the chance of over-feeding. Catfish in cages should be fed daily. At that place is some evidence that feeding catfish twice per twenty-four hours, especially under raceway atmospheric condition, results in a faster growth rate.

Automatic feeders and mechanical distribution of feed is common in channel catfish culture (meet Appendix Fourteen).

8.2.three Tilapia

In the wild, tilapia feed more than or less continuously throughout the day. Manual feeding, several times per solar day is best for intensively grown tilapia, in cages or raceways for instance.

Automatic feeding can be employed and the blower type of feeder is said to distribute feed more adequately for tilapia. Tilapia fry should exist fed at least 4 times per mean solar day, preferably 8 times per day, in daylight hours. In an experiment with 9 mm full length fry of Oreochromis aureus, New et al., (1984) showed that survival improved with continuous (mechanical) feeding compared to either five or three manual feeds per day. Feeding rates tin be less frequent, iv or 5 times per mean solar day for fingerlings. Adult tilapia thrive best on two-3 feeds per 24-hour interval.

viii.2.4 Carp

Over again, common bother (and probably Chinese and Indian carps) thrive all-time on frequent feeds. Jauncey (1982) reports that one researcher found that optimum feed utilization by common carp (at 40 grand size) was achieved when the feed was split into nine equal feeds. The best feeding frequency tin only be assessed on an private farm basis, determined past the cost of repetitive feeding operations. From the biological and nutritional betoken of view information technology would announced best to feed as oft as possible.

viii.2.5 Other Fish Species

Specific feeding frequency recommendations for the other cultured species of fish covered in this manual are non available. It is therefore recommended that until more than information on the optimum weather becomes bachelor those frequencies found best for catfish and tilapia should be applied. A gold rule would exist, when in doubt, to feed equally frequently as economic science permit. At that place has been a report, however, that groupers gave best biomass increase and good FCR, fed 'trash' fish to satiation in cages, when fed every 2nd day, as compared to other frequencies varying from in one case every 5 days to three times per day. However, this consequence was apparently acquired past poorer survival at the higher feeding frequencies. Best growth charge per unit was, again in this case, achieved by feeding two or iii times per day.

8.2.vi Shrimp and Prawns

There is a proficient bargain of controversy virtually the optimum time and feeding frequency for marine shrimp and freshwater prawns. Some species couch during the day and feed about actively at nighttime. Others feed in the shallower parts of the pond but avoid these areas in daylight when temperatures are highest. For these species it would seem best to feed in the belatedly afternoon or early evening. Near farmers feed once, or at the most twice per 24-hour interval, usually beginning thing in the morning time and last affair in the afternoon.

Shrimp practise not consume all of the feed presented at once, unlike most fish. This fact has led to much give-and-take and research on methods of bounden shrimp feeds to prevent wastage and the loss of h2o-soluble nutrients. Some commercial feeds are extremely water stable (>24 hours) but may non be so palatable as softer feeds. The apparent need to produce such well-leap diets has, in part, been caused past the reluctance to feed shrimp and prawn ponds more oft than once a twenty-four hour period, fifty-fifty though labour is often available and otherwise unoccupied. Feed presented in smaller quantities more frequently would not need to be so efficiently bound and should therefore exist cheaper.

In Taiwan many intensive farmers (normally farms are run by a family unit enterprise, and so there is always someone on site) feed tiger shrimp (Penaeus monodon) 4 to half-dozen times per twenty-four hours, the feeds existence evenly spaced over the whole 24 hour flow.

I propose that feeding shrimp and prawns as ofttimes as possible, spreading the daily ration between those feeds, would exist the nigh effective technique. It certainly pays off with young postal service-larvae, equally it does with fish fry. Shrimp larvae do not thrive at all unless maintained in a conditions where nutrient (live food or artificial feed with neutral buoyancy) is constantly available.

8.iii Biomass Assessment

Adding of the corporeality of feed to present daily must be based on an assessment of the biomass (total weight of fish or shrimp) in each swimming or enclosure.

Regular, authentic, data for average animal size must be obtained through weekly, bi-weekly or, at the worst, monthly sampling of the rearing unit. In tanks or cages it is easier to take representative samples but in ponds it is common to get a biased moving picture, particularly when a species with uneven growth rate is stocked, such as freshwater prawns. Care must exist exercised to take samples in several parts of the swimming, not only at feeding points where the larger or more active individuals may besiege. Samples may be taken by seine, cast net or lift net.

If accurate length/weight relationships for the species have been pre-adamant under the ecology atmospheric condition existence used, length measurements are a more accurate ways of monitoring growth rate. This is particularly truthful of crustacea which hold uneven quantities of water under their carapace. Measuring length can be a rapid procedure with a skilled operator and is less stressful to the animals than trying to determine weight by a standardized technique. Fish length can either be total or, to avoid inaccuracies due to harm to the tail fin, is more accurately measured to the anterior stop of the caudal fork. Care must be taken that the method of measurement corresponds with that used when the length/weight ratio was determined. Similarly total shrimp length, because of frequent rostrum harm, is less reliable than measuring from the posterior of the eye orbit to the tip of the telson.

For a pond of v 000 m², stocked at 10/thouⁱⁱ, at to the lowest degree 5 samples should be obtained at each sampling time and 50 animals from each sample measured. Average weight can either exist calculated directly from the total weight of the sample obtained by weighing or past referring the average of the measured lengths to a length/weight ratio.

An assessment of survival is too necessary to summate feeding rate effectively. This tin exist illustrated every bit follows. If a pond is stocked with 50 000 animals and, at a sampling date the boilerplate weight is ten g and the feeding charge per unit to be practical is iii% of the biomass/mean solar day, the amount of feed would be:

if information technology is causeless that all the animals originally stocked are still present. If however, there has been a 20% bloodshed up to the 10 1000 size, the correct amount of feed should be:

Besides saving twenty% of daily feed costs in this case, an accurate cess of survival, too as growth charge per unit, would forbid possible water quality deterioration caused past over-feeding.

Although a skilful gauge of survival aids an effective feeding programme it is ofttimes extremely difficult to achieve. In small cages and tanks it is frequently possible to brand authentic visual observations or to count all the animals during their transfer to another tank or muzzle. This is normally impossible or impractical in swimming civilisation, except when stock transfer from ane swimming to another takes place for other reasons. In this instance the numbers present tin can be calculated by taking the full weight of stock and dividing by the boilerplate creature weight obtained from samples. Visual observation is as well incommunicable in ponds. In my view, no-one has yet devised a satisfactory way of assessing the stock in aquaculture ponds, which is why this important subject is rarely mentioned.

In do most subcontract managers apply an arbitrary survival factor based on the number of days since stocking. This cistron is derived from noesis of previous civilization cycles on the same farm or elsewhere in similar circumstances, modified past ascertainment of actual mortalities, knowledge of water quality or affliction problems, etc. The factor derived depends on accurate measurement of the number of animals originally stocked and the numbers harvested in each wheel for its accurateness. Thus the importance of careful farm records becomes obvious.

If those records show, for example, that l% of the animals stocked ordinarily reach market place size (barring individual accidents) on the specific farm, information technology would be reasonable to assume that time to come growing cycles would show the aforementioned survival rate. Similarly, if there is no transfer of animals within the growing period, the highest mortality rate probably occurs afterwards initial stocking (due to the handling stress and the ease of damage and of predation on young animals). Thus, if a 50% mortality is known to occur normally betwixt stocking and harvesting in a 16 week growing bike, for example, it would exist reasonable to assume that 20% of the losses occur within the starting time 4 week menstruation with a further 10% loss occurring during every iv week period after that. Thus assessments of biomass in this example at two weekly intervals of a pond stocked with 50 000 animals would exist based on multiplying the average brute weight, obtained by measurement of samples by the following number of animals:

Weeks 1 and ii
Weeks 3 and four
Weeks 5 and half-dozen
Weeks 7 and 8
Weeks 9 and 10
Weeks 11 and 12
Weeks thirteen and 14
Weeks 15 and sixteen

Thus, to continue this example, if the average weight of prawns at the beginning of week 13 (12 weeks afterwards stocking) was twenty k, and the percentage of biomass to be applied was five%, the daily amount of feed would exist:

Conspicuously cess of biomass, particularly in ponds, depends partly on accurate sampling and size measurement just besides very much on the manager'due south sentence based on an accurate record of past feel modified by the history of the detail batch beingness cultured.

Farther reading for section 8:

Piper et al., (1982); Halver (1972); Phillips (1970);Gaudet (1967); Lee (1981); Ralston Purina (1974); Marek (1975); Foltz (1982); NRC (1983); NRC (1981); Pullin and Lowe-McConnell (1982); Jauncey and Ross (1982); New (1986a); New and Singholka (1982); Winfree (1979); Jauncey (1982).

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Source: https://www.fao.org/3/S4314E/s4314e09.htm

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