Cages for farming milkfish. (Photo: SEAFDEC)

Researcher's new feed makes for better milkfish

A scientist at the Southeast Asian Fisheries Development Centre (SEAFDEC) who specializes on larval nutrition is working to devise the optimal feed for milkfish broodstock.

In 2011, Ofelia S Reyes made a type of feed that is fortified with arachidonic acid, a fatty acid. She saw 96 per cent of the milkfish eggs develop into normal larvae, up from 84-89 per cent seen in 2001 without feed fortification and 94 per cent in 2007 with fortified feeds.

Her research takes into account the role played by micronutrients that are necessary for egg growth and for the development of the gonads where the eggs form.

AQD researcher Ms. Ofelia Reyes working at her lab. (Photo: SAFDEC)

“Because of the high percentage of normal larvae with the new feed, it means it’s good for larval rearing, with a high survival rate after the hatchery phase of 21 days to 26 days,” she said, Malaya reports.

Arachidonic and betacarotene micronutrients are added to the diet via feed pellets made from fish meal and soy. These pellets cost about PHP 68 (USD 1.60) per kg versus the conventional pellet at about PHP 50 (USD 1.18) a kg.

The fortified diet will be presented at SEAFDEC’s Integrated Finfish Broodstock and Hatchery Complex later this year and, following a thorough review, SEAFDEC will recommend the new formulations.

Although vitamins C and E are already used in the conventional diets of milkfish broodstock, this will be the first time that arachidonic and betacarotene are being recommended for inclusion.

These micronutrients are already used in temperate countries for spawners like salmon and have been proven there to improve egg quality.

“We went into micronutrients because sabalo spawners were already domesticated and had no access to natural food in the sea that is rich in micronutrients,” Reyes said. “You have to improve on the micronutrients that are incorporated in hatchery feed.”

The formulations are especially crucial for milkfish raised in concrete tanks because, unlike fish raised in the open sea, they lack access to micronutrients.

Reyes observed the broodstock in 20- and 10-ton larval tanks at SEAFDEC’s Integrated Fish Broodstock and Hatchery Complex, similar to conditions in actual hatcheries.

Bangus farms normally obtain their fry supply from hatcheries which themselves rely on broodstock hatcheries.

But Reyes said that farmers complain of the high mortality and slow growth of local and imported milkfish fry.

“So it was time to improve the feed for local milkfish broodstock to produce more fry and satisfy the demand of bangus producers,” she commented.

The SEAFDEC intervention is meant to offer broodstock farms the fortified feed that will ensure better quality fry production.

“Because of this intervention, quality supply is assured,” Reyes said.

“Due to the improvement in and expansion of milfish aquaculture, the demand for good quality seeds is increasing,” she added. “One way to meet the demand is to improve the nutrition of broodstocks by providing specific micronutrients and improve spawning frequency, produce good quality eggs and eventually improve the survival of larvae.”

By Natalia Real
[email protected]
www.seafood.media

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