Adapted first feeding strategy shows promising results for Peruvian customer

The Truchas Arapa company in the region of Puno, Peru, decided to run a trial in feeding management, keeping in mind the territorial behavior of the largest trout compared to the smallest. Usually, in the reincubation and fry room, the first feeding begins when 80% of the fry have reabsorbed the yolk sac. However, the downside of this strategy is that when the stronger trout wait longer for feed, this negatively impacts their genetic potential throughout the rest of their growth. For better results, they decided to trial a new approach where the fry are moved to another productive unit as soon as they reabsorb the yolk sac to start the first feeding. With this change, the fry have the opportunity to feed as soon as needed without waiting for the others to reabsorb the sac.

In this context, two first feeding strategies were tested during the first 49 days that the Troutlodge fry learned to eat. These were:

1. Separate the stock of fingerlings that have finished reabsorbing their sack from the rest. The density reached up to 180 fingerlings/Lt. This, we will call the transfer approach.
2. Wait for 80% of the fry to reabsorb their yolk sac and start feeding at a density of 120 fry/Lt. This, we will call the standard approach.

The eggs were reincubated in vertical systems. For the first feeding, fiberglass troughs were used. The average daily temperature was 12C. The average water flow at entry was 1.5 Lt/min/1000 fingerlings.

“It’s always somewhat daunting to try something new in your operations. But with the support and guidance from the Troutlodge team, we decided to take the risk. In the end, we are very pleased with the results from the trial and have gained some important insights in achieving success in the first days of hatching.” - Truchas Arapa

The transfer approach

A trough and seven baskets were used for the Californian system where the fry were transferred. The fry that had finished reabsorbing their yolk sac and had started to float in the vertical incubators were transferred to the Californian system to start the first feeding.

The standard approach

The trough with the same dimensions, but without baskets, was used. It is expected that 80% of the fry had finished reabsorbing their yolk sac to transfer them all to the troughs and start with their first feeding. In both cases, the depth of water was the maximum possible.

Measured productive indicators

The evaluation was carried out during 76 days from the reincubation of eggs. The productive indicators in comparison were the daily mortality rate, accumulated mortality and average weight

Results

Daily mortality

As expected, the percentage of daily mortality increased during the hatching process and a few days later they started feeding. Daily mortality was similar during the hatching stage, however, they differed from the beginning of the first feeding. This could be due to the feeding strategy. In the transfer approach, a more uniform feed capture, lower percentage of unconsumed feed and fewer pinhead fry were observed. The increase in daily mortality in the standard approach is most likely due to starvation of the smaller fry.

Feeding began 24 days after reincubation of eggs. From the first day of feeding to day 50, a great difference in daily mortality was observed between both strategies. From day 24 to day 76, the follow-up period showed 88% more mortality in the standard approach compared to the transfer approach.

Accumulative mortality

From day 28, significant differences are appreciated, the transfer approach had 46% less accumulated mortality than the standard approach. The difference at day 76 is undeniable.

Average weight

The graph shows the weekly average weight since the start of feeding. Results showed that from the third week, there was a difference between the average weights. With the transfer approach, at day 44, 23.5% more in weight was achieved than with the standard approach. At day 76, the difference was 33.3%.

The difference in average weight is likely because the fingerlings from the transfer approach were fed on time and did not lose their growth potential by waiting for the rest of the fingerlings to start feeding.

Final insights

First feeding strategies play a vital role in trout production. This is reflected in the productive indicators. Moving the fry and starting the primary feeding when required allows for the best use of the feed. In addition, it improves the survival of the biomass. These results show that an adapted feeding strategy can have a significant impact on unlocking genetic potential and getting the most value in your operations. Well done to Truchas Arapa for achieving great results!