Effects Of Breeding Density,Light Conditions And Types Of Food Waste On The Growth And Body Composition Of Hermetia Illucens L.

China is a country with a great demand for raw protein,with over 70%of which especially fish meal and soybean meal coming from other countries.However,our breeding industry is now facing serious challenges of maintianing a sustainable dvelopment due to resource stocks and climate change;for example,fishmeal production is declining year by year,and soybean meal prices always remain high.In recent years,animal nutritionists have begun to seek other animal protein sources,and insect resources have consequently become a research hotspot in the feed industry.Hermetia illucens L.also known as black soldier fly,is a high-quality and environmentally friendly insect rich in protein and lipid.it is a saprophytically fed larvae wth a strong feeding capacity and has an obvious advantage of efficiently transforming food waste;the adult has a short lifespan and rapid reproduction,,which does not cause any harrassment to people or carry harmful substances such as germs.Processing food waste with Hermetia illucens L.,can not only effectively alleviate the environmental pollution caused by the growing food waste,but also obtain insect products rich in protein,fat,amino acids and fatty acids,which can be used as a high-quality feed material for animal feed production.In this paper,both the larvae and pupae of Hermetia Illucens L.were taken as the objects to study the effects of different breeding densities,light conditions and waste types on their growth,production performance and body composition.The aim is to screen favorable conditions for the production of Hermetia illucens L.in the utilization of food waste,so as to provide theoretical basis and research ideas for large-scale use of Hermetia illucens L.In treating food waste and producing new high-quality protein sources.Test 1 Effects of breeding density on the growth and body composition of Hermetia illucens L.5 density groups were designed and labelled as D500,D1000,D1500,D2000 and D2500,respectively.A total of 22,500 Hermetia illucens L.larvae aged 7 days(initial weight of 8.26 mg,body length of 5.48 mm)were selected and randomly assigned to 15feeding boxes of the same size in proportion,with 3 duplicates for each density group for a period of 18 days.In Test 1,all groups were feed with the same proportion of rice waste under the same temperature,humidity and light;the growth and development of larvae were monitored every 3 days;after the 18-day test,the conventional components and fatty acid content of the objects were examined.The results showed that with the increase of the breeding density,the growth rate of Hermetia illucens L.larvae has increased significantly,as well as the survival rate and pupation rate of the larvae,and the crude protein,crude fat,lauric acid(C12:0),myristic acid(C14:0)synthesized in the body.The grwoth indicator of the Hermetia illucens L.is at the best level when the density is increased to D2000(0.51/cm~3)and can synthesize over 65%lauric acid(C12:0).When the density is raised up to D2500(0.64/cm~3),some of the indicators and body composition experienced a trend of decline,but the single yeild,somatic crude protein and saturated fatty acid has indicated a continous increase.Based on the comprehensive indicators,D2000(0.51/cm~3)was suitable for small-scale breeding of Hermetia illucens L.larvae,and D2500(0.64/cm~3)was suitable for industrial production of Hermetia illucens L.larvae using food waste.Test 2 Effects of lighting conditions on the growth and body composition of Hermetia illucens L.A total of 3 lighting modes were designed,namely full-light group(normal daylight),half-light group(shading for 7.5h during the day)and shading group(shading for15h during the day).A total of 7200 larvae aged 7 days(initial weight of 7.77mg,body length of 5.89mm)were selected and randomly assigned to 9 feeding boxes of uniform size,800 larvae per box,with 3 duplicates for each treatment group.In Test 2,all groups were fed with the same quality of rice waste under the temperature of 28~oC～30~oC and humidity of60%～70%.The lighting conditions were set according to the current season light cycle(light:dark=15h:9h),and the indoor photometric quantity is 1000LUX.The larval growth index was measured every 3 days for the larval activity and death;after the 18-day test,the conventional components and fatty acid content of the worm were tested.The results showed that all the 3 light conditions were suitable for the growth of Hermetia illucens L.;by contrast,the production efficiency is better under half lighting than full lighting(P<0.05),and best under shading lighting(P<0.05).Appropriate reduction of light duration was more conducive to the growth and development of Hermetia illucens L.larvae and the accumulation of body components such as crude protein,lauric acid(C12:0)and myristic acid(C14:1).Test 3 Effects of different types of food wastes on the growth and body composition of Hermetia illucens L.3 treatment groups were set,namely the rice group,the mixture group(rice and offal),and the offal group.A total of 7200 larvae aged 7 days(initial weight 7.84mg,body length 5.87 mm)were selected and randomly assigned to 9 boxes of uniform size,800 larvae per box,with 3 duplicates for each treatment group.In Test 3,the condition was maintained under the same light,with a temperature of 28~oC～30~oC and humidity of60%～70%.The 3 treatment groups were fed with the equal amounts of rice waste,rice waste and offal mixture and fish offal in the form of dry matter.Larvae growth indicators were measured every 3 days,and the activity and death were recorded.When the pupation rate of offal group was 5%,the test was finished,and the contents of conventional components and fatty acids in the objects were examined.The results showed that Hermetia illucens L.had the best growth performance and development in the mixture group,and the growth indexes of this group were significantly higher than those of the other 2 groups(P<0.05).In the offal group,the body were rich in crude protein and linoleic acid,while its growth rate and pupation rate were significantly lower((P<0.05).Hermetia illucens L.in rice group had a higher tendency of intaking lauric acid(C12:0),while the Omega-3 fatty acids contained in the body of the mixutre group were significantly higher than that of the offal group.Therefore,rice waste produces better performance in the process of transforming food wastes of high animal protein such as offal.All in all,the transformation of food waste with Hermetia illucens L.is promising.When Hermetia illucens L.is transforming the food waste,natural light should be kept within 7 hours,and the mode of shading light can be used if necessary.Breeding young larvae at a density of 0.64/cm~3 and mature larvae at a density of 0.51/cm~3 is more desirable.When handling or transforming food waste of high animal protein,adding food waste of proper carbonhydrate might be a better approach.