Scientifically Speaking …
By Matthew Wedzerai
BSF IN PIGLET DIET: A PROTEIN SOURCE AND WELFARE TOOL Black soldier fly larvae can be used as protein source in diets for growing pigs and has the potential to replace soybean meal without compromising performance. On the other hand, the larva is a valuable edible enrichment that positively manipulates piglet behaviour for improved post-weaning welfare. These were the conclusions by researchers from Wageningen University and Research, and Leiden University, in The Netherlands. The two studies that evaluated the potential of black soldier fly (BSF) larvae as a protein source substitute for soybean meal in growing pigs, and as an effective edible enrichment post-weaning were recently published in the journal Nature. The search for sustainable alternatives has led to a growing
interest in insects as an alternative protein source in diets for farm animals. Insect meals as a protein source can deliver nutrients, and compared to the production of other dietary protein sources, insect production has a small environmental footprint. Following the recent EU approval on the use of insect protein in poultry and pig feed, insects might be the future we need to promote more sustainable agriculture. On the other hand, exploring and eating edible enrichment allows piglets to develop feeding-related behaviours such as chewing, adapting them to consuming solid feeds while simultaneously benefitting gut functioning.
Soybean substitution study Sixteen post-weaned male pigs were randomly assigned to two groups and fed for three weeks with iso-caloric and iso-proteinaceous experimental diets prepared with either soybean meal (SBM) as reference protein source or with BSF as single source of dietary protein. At the end of the trial, the pigs were sacrificed to collect relevant digesta, gut tissue and blood samples to study changes induced by the dietary treatments using FeedOmics based analyses.
Protein source with antimicrobial effects In this study, the researchers found that, in addition to being a good source of amino acids (AA) as part of the “strict-nutritional” value, BSF, compared to SBM, has the capacity to deliver other “non- strict-nutritional,” functional properties characterized mainly by the appearance of alpha-aminobutyric acid and taurine in plasma of BSF fed pigs. Alpha-aminobutyric acid is a key intermediate in the synthesis of a tripeptide analogy of glutathione with antioxidative properties that can support health of pigs. Taurine can exert health benefit effects in
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pigs by providing protective effects via regulating immune responses and restoring tight junctions in the gut mucosa when piglets suffer from oxidative stress. Inclusion of BSF in the pig diet also resulted in a significant increase
in “beneficial” microbes that help maintaining and supporting intestinal health and functionality. A decrease in abundance of Streptococcus showed the antimicrobial effect of supplementing BSF. The antimicrobial properties were attributed to the presence of medium chain fatty acids or antimicrobial peptides in BSF. The researchers concluded that it is reasonable to conclude that BSF can be used as protein source in diets for growing pigs and have the potential to replace SBM.
Similar performance Growth performance was not different between the SBM and BSF diets, which is in line with results of other studies in which dietary inclusion of BSF replacing SBM did not affect growth performance of pigs. In this study, insect meal from BSF was included in the diets as the only source of protein to replace SBM on an iso-nitrogenous and isoenergetic basis, while not fully balancing the diets for the level of essential AA. This could have affected the growth performance of the pigs. The emphasis was that this observation should not be overstated as the trial was not set up as a performance study, which would normally require a higher number of animals per treatment.
Environmental enrichment study To study the use of BSF as an environmental enrichment tool, a total of 32 piglets weaned at around 25 days of age were assigned to either the control (CON) or the black soldier fly larvae (LAR) treatment (8 pens/treatment). Piglets were provided with wood shavings (CON) or live BSFL (LAR) twice a day, at 09:00 and 13:00 h, by scattering the larvae in the pen on the wood shavings bedding. Wood shavings were provided to the CON treatment to create a similar disturbance in all pens. LAR pens received either 75 g (day 1–4) or 150 g (day 5–11) of live larvae twice a day, and CON pens always received a similar volume of wood shavings.
Beneficial behaviour In line with the researchers’ expectations, live BSF larvae provisioning redirected exploration and manipulation behaviours away from objects and conspecifics and towards the floor where the larvae were provided, while simultaneously decreasing aggression. These effects occurred over the whole day despite the larvae being only transiently present each day, indicating that temporary access to live BSF larvae can benefit piglet welfare. The researchers also mentioned that providing enrichment can have stress-reducing effects on pigs, and as such, the presence of larvae may have attenuated the piglet’s weaning stress. “This could have shifted their behavioural repertoire towards more favourable behaviours and reduced aggressive behaviours”, they said.
Nutritional equivalence It was suggested that the absence of any effect of whole live BSF larvae consumption on total dry matter intake, net energy intake,
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