Title:               Results of feeding trial assessing ADAM & AMOS feed against three other  feeds for growing Haliotis 
                        iris 

PENDARVES ABALONE FARM LIMITED

Office & Farm: Chertsey Kyle Road

Ashburton

PO Box 16 479

Christchurch

New Zealand

E-mail: n.ragg@zool.canterbury.ac.nz

All feeds trialled at PAF have been tested in the same way:

50 juvenile black-foot abalone, Haliotis iris, were individually tagged and shell length measured (vernier callipers to +/-0.1mm); each abalone was drained of excess water by inverting on absorbent paper for 2 mins and then weighed (+/-0.01g). The animals were stocked to an opaque 40litre tank receiving approximately 2 exchanges of coarse-filtered seawater per hour. The target feed was supplied every 3^rd day at approximately 200% of satiation. Every second ration (every 6^th day) the dry weight of food stocked to the tank was recorded, after 3 days all uneaten food was then siphoned into a pre-weighed 80m m screen.

The screen and uneaten food were dried at 60° C for 48h and weighed (no correction was made for the fraction of faeces present). Animals were treated in this way for 3 months, at which point each individual was weighed and measured, this initial period is regarded as an acclimation to the diet but the data collected is of comparative value and allows obviously low-grade diets to be identified and discontinued. An additional 3 month monitoring period then allowed true performance to be evaluated, diets of particular interest were subsequently monitored for a further 9 months. Water stability of each diet was also examined by feeding an unstocked tank and subsequently re-weighing the food.

As abalone of different sizes and populations tend to show variable response to a specific treatment, each diet was offered to 2 tanks of animals – the first containing juveniles (15-25mm) from a South Island hatchery, the second with larger (30-40mm) animals spawned in the North Island. A 3^rd tank was included for diets of particular interest or high variability in response.

Animal performance was expressed in terms of linear shell growth (m m/d) and % weight gain per day, Specific Growth Rate (SGR), according to equation 1.

Ln(W₂) – Ln(W₁)

SGR = _________________ . 100 1).

t

where W₁ and W₂ represent individual animal weight before and after t days, respectively.

Individual SGRs and shell growth are summarised as tank averages (+/-Standard Error). Average SGR is used to estimate total tank biomass on each day of the experiment, thus allowing the calculation of the following feeding performance parameters:

Apparent Ingestion is simply the weight lost by the food, standardised by biomass to give grams of dry food eaten per gram of abalone biomass per day.

Apparent Food Conversion Ratio (FCR_a) is calculated from equation 2:

(F_out – F_in)/3

FCR_a = ______________ 2).

B_c - B_c-1

where F_in and F_out are the dry weights of food added and removed from the system, B_c is the current day’s biomass estimate and B_c-1 is the preceding day’s biomass estimate.

FCR is a measure of the efficiency with which ingested food is converted to abalone biomass, the lower the FCR, the more efficient the process; an FCR of 1 implies an impossible 100% efficiency. However, these experiments DRY food ingested is divided by WET biomass gain, hence FCRs of <1 are frequently obtained.

Note that both ingestion and FCR are ‘apparent’ – this refers to the commercial, rather than biological nature of the parameters, i.e. they refer to the total amount of food that must be supplied to a system to yield the measured growth, irrespective of whether the food leached, dissolved etc. FCR_a is subsequently multiplied by feed price to produce an estimate of the food cost associated with each Kg of abalone growth.

Stability in water was quantified as % weight loss/d.

Only trials that included ADAM & AMOS products are included in this report. A 6 month trial period, running from Nov. 98 to May 99 is described. 7 treatments were examined, 3 ADAM & AMOS diets: AAFD, AAFM and AAOP, 3 other commercially available diets (undisclosed), termed X, Y and Z, and a mixed diet consisting of 80% AAFD supplemented with other commercial diets (NB following a year of trials of this kind prior to the 6 month trials that included the ADAM & AMOS diets, products X, Y and Z had been identified as being the most promising of any artificial or natural diets tested).

Water temperature rose steadily from 13.5 to a maximum of 17.0° C in Feb., falling to a minimum of 13° C by May; dissolved oxygen remained above 90%, ammonia was undetectable, pH>8.

The data presented largely speaks for itself, warranting little discussion – it is clear that the products AAFD and AAFM, with combined low product cost, efficient FCRs and rapid growth rates result in substantially reduced abalone production costs.

These six-month trials show no apparent benefit to supplementing AAFD with other, higher cost feeds.

Product X was deemed inappropriate and trials were discontinued.

AAFM clearly outperformed AAFD during the acclimation period, subsequent performance differences however have been marginal.

AAOP has poor water stability properties resulting in high apparent FCRs and consequently high abalone feed costs.

The above experimental protocol has proved cumbersome to operate, hence a streamlining of procedures is in progress: Feed consumed will be assessed less frequency but with greater accuracy, by drawing siphoned water through a 0.2m m GF/C filter under vacuum. Ingestion parameters will not be measured during the acclimation period. AAOP trials will be discontinued.

Additional treatments have already undergone acclimation, performance assessment will commence on 15.7.99; the new treatments are AAOP+, AAMD and a rival Australian diet. Trials using AAFM, AAFD, AAFD mix, product Y and Z will be continued.

In addition to the above trials, qualitative observations of the performance of noodle vs. pellet-form feed in various grow-out systems and flow regimes will be made. PAF welcomes the opportunity to test any promising new products or variables.

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