Algae meal or insect larvae? New pig feed alternatives?

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Algae and insect larvae represent interesting feed alternatives within pig nutrition.

In the following study,researchers evaluated a complete dietary substitution of soybean meal (SBM) for algae meal composed of Spirulina platensis (SM) or partially defatted larval meal containing Hermetia illucens (HM). This was assessed for both piglet and growing pigs’ feed.

The world’s population has grown steadily in recent decades. It is estimated that by 2050, the world’s population will reach approximately 9.7 billion people. This brings with it, a 70% increase in food demand. With changing consumption patterns, meat shares a part of such increase within the growing demand for animal products. Global meat production is expected to increase from 320 million tonnes in 2016 to 360 million tonnes in 2025. Pig production accounts for 36% of global meat production with a growth rate of 12%.

Consequently, large amounts of feed proteins will be needed, and within this current global scenario soybean products are the main protein source in pig diets. Therefore, these act as a reference point, for the search of alternative sources that can help meet future protein demands. However, adequate feeding alternatives are still required. Algae production represents an acceptable alternative, as this type of aquatic biomass is able to develop under marginal land use. In addition, insects represent another potential alternative protein source considering that their larvae have a very quick development.

The microalgae Spirulina platensis is a prokaryotic multicellular cyanobacterium. Spirulina algae are photosynthetic organisms which only grow under warm climates and high luminous intensity. They develop in alkaline salt lakes and basic bodies of fresh water.

algae

The black soldier fly Hermetia illucens is a widespread fly belonging to the Stratiomyidae family which are part of the Diptera order. Hermetia larvae have the capacity to use a wide range of nutrient sources and can develop rapidly between 20°C and 30°C.

In general, both alternative protein sources, have the potential to be included as animal feed.

Objective

As part of the multidisciplinary project “Sustainability transitions in the food chain” (supported by the Ministry of Science and Culture of Lower Saxony), the present study aimed to measure the quality of proteins from piglet and fattening pigs’ diets based on nitrogen balance studies (N) with a high inclusion of Hermetia flour (HM) or partially defatted spirulina flour (SM) with a gradual amino acid (AA)supplementation.

Materials & Methods

Animals: 16 piglets and 16 fattening pigs
Diets: 4 pelleted diets
Main feed ingredients were: wheat, barley and HM or SM

Two age-dependent nitrogen (N) balance studies (average body mass of 25 and 60 kg) used 16 male castrated piglets and 16 fattening pigs to measure N utilization parameters in diets with complete substitution of soybean meal (SBM) with alternative protein sources (SM, HM). Including different grades of AA supplementation.

The main ingredients used within the experimental diets were: wheat, barley, and SM or HM. The final diets contained SM or HM with the following levels: 21% (piglets) and 13% (growing pigs). Nitrogen balance (N) studies were applied to measure the parameters of apparent nitrogen digestibility, complex dietary protein quality and individual amino acid (AA) efficiency. This was done according to the “Goettingen approach”.

Results:

Lysine supplementation at 80% of the recommended lysine (Lys) supply in the HM (A) and SM (A) diets produced similar protein quality data (63.6 ± 2.1 and 63.7 ± 3.4).
Surprisingly, only in the HM piglets’ (AA) diet did prolonged AA supplementation (Lys, methionine (Met), threonine (Thr)), improve protein quality (72.8 ± 6.7) significantly (p = 0.004).
Similar trends were observed in growing pigs.
However, when the level of histidine (His) in the MS (AA) diet was increased, the quality of the feed protein (71.8 ± 1.3) improved significantly (p <0.001). WHich highlights the importance of an adequate supply of His in diets with a complete SBM substitution for algae flour (MS).
AA efficiency data expands the possibilities to explain observed responses in regards to protein quality.
If a proper AA balance is assured from a nutritional standpoint, both alternative proteins can replace SBM in pig diets.

Conclusions

The diets used within the study were well accepted by the animals. Extended levels of AA supplementation produced better protein quality for the diets with both alternative feed proteins.

Nitrogen balance studies emphasize the superior protein quality of pig diets with high inclusion levels of algae meal (Spirulina platensis) or insect meal (Hermetia illucens). Considering that an adequate amino acid supplementation is ensured.

Source: Department of Animal Sciences, Division Animal Nutrition Physiology, Georg-August-University of Goettingen, Alemania. doi: 10.3390/ani8100172.