NEW PROTEINS ▶▶▶
Its similar protein con- centration and essential amino acid profile makes mussel meal a potential substitute for fishmeal.
plague in mussel farms, can cause losses in mussel produc- tion. This is why wild starfish are often removed from mussel cultivation sites. This creates an underutilised by-product of mussel farming which is suitable for consumption by animals. The mussels used for animal feed can be those not suitable for use as food (usually due to their size). Alternatively, as mussels filtrate nitrogen (N) and phosphorus (P) out of the water, mussels cultivated in order to mitigate eutrophication may be used. This creates a circular stream of nutrients in which excess N and P from land-based activities are recycled back into the food chain. Moving from the water to land, in- sects are also a potential novel protein source. Insects are of particular interest because of their ability to utilise waste and rest materials. Moreover, the physical rearing of insects re- quires very little (arable) land. Indirectly, however, the sub- strate provided to insects may have some arable land use as- sociated with it. For black soldier fly and yellow mealworm large-scale production sites have been established and these insects are thus often used in scientific research. The lesser mealworm is another potential candidate for feed with estab- lished production. A prerequisite for using ingredients in feed is their potential to supply nutrients for growth without growth inhibiting elements. In this respect, the protein con- centration and matching the ingredients’ amino acid (AA) profile with the animals’ requirements are fundamental.
Mussel meal Mussel meal, which is derived from mussel meat, can have a crude protein (CP) concentration of between 60-70% dry matter (DM), which is comparable or slightly below the pro- tein concentration often observed in fishmeal. Besides its protein concentration, its similar essential amino acid profile makes mussel meal a potential substitute for fishmeal. In-
deed, a high ileal digestibility of 83% was found several years ago when feeding ileal cannulated pigs with mussel meal. It has previously been shown that laying hen performance in experimental facilities is maintained when 4-12 % mussel meal is included in diets, thus totally replacing fishmeal. Simi- larly, broilers and finishing pigs have been found to perform well on diets containing mussel meal. Additionally, the die- tary provision of mussel meal can enhance the yolk colour of eggs due to the presence of carotenoids. This colouration po- tential may differ depending on carotenoid uptake as the mussel grows. Recently, the focus has been on using different processing methods for the production of mussel meal. A drawback in the production of meal from mussel meat is the high − and expensive − input of energy and water for boiling to remove shells. Another less energy demanding form of mussel meal, i.e. filtrated mussel meal containing shell parti- cles, has therefore been experimentally evaluated. As the shell is not entirely removed, salt and shell particles heighten ash and consequently lead to a lower protein concentration in shell-reduced mussel meal. Group housed (six pens) laying hens at a commercial farm were fed diets containing either 3% fishmeal, 5% deshelled mussel meal or 6% shell-reduced mussel meal from 23 weeks of age (after egg laying had be- gun). Laying hens were held according to organic regulations. At several hen ages, 25 eggs were collected for quantitative analysis of the egg quality. Shell strength was maintained when feeding either type of mussel meal compared with fish- meal. Feeding shell-reduced mussel meal enhanced the or- ange colour of the yolks compared with fishmeal. Further- more, the presence of omega-3 fatty acids in deshelled mussel meal led to enhanced deposition of omega-3 in eggs. Nevertheless, feeding shell-reduced mussel meal reduced egg weight (by 2 grams on average), which coincided with lower bird liveweight gain. The high salt concentration in shell-reduced mussel meal was probably the reason for this.
Starfish meal With an average CP concentration of 39% DM, starfish meal is generally less rich in protein compared to fishmeal. Starfish meal contains considerable levels of essential amino acids, al- though most are slightly lower than the levels found in fish- meal. Still, as with mussel meal, protein from starfish meal has been found to be well digested by pigs, with a standard- ized ileal digestibility of 80%. Meal from starfish can, howev- er, contain from 20% up to over 50% ash. This highly variable ash concentration is attributable to fluctuations in nutrient composition during the starfish’s reproductive cycle. In star- fish from Danish waters, a study on seasonal variation has shown that proper choice of harvesting time maximises pro- tein and minimises ash content. Despite its high ash content, starfish meal can replace fishmeal and maintain the growth performance of growing pigs and laying hens. Nevertheless, inclusion of more than 7.5% starfish meal has been shown to
14 ▶ ALL ABOUT FEED | Volume 29, No. 8, 2021
PHOTO: SHUTTERSTOCK
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