Effects Of Different Grain Size Diets On Digestibility And Feeding Effect Of Apis Mellifera Ligustica

The granularity of animal feed affects the digestibility of animal feed and the physiological function of animal body.Pollen substitute feed is more and more widely used in apiculture,and the granularity of pollen substitute feed also affects bee digestibility and physiological function.However,the effects of feed granularity on feeding digestibility and physiological function of honeybee were not reported.Therefore this study Italian bee as the research object,through feeding 100 mesh,200 mesh generation of pollen forage and 300 purpose,explore the feed particle size on protein digestibility,feed intake,bees swarm group of potential,sealing lid,birth weight,body composition,blood lymph in the physiological and biochemical indexes,intestinal morphology,the effect of antioxidant and immune capacity.It provides reference for the selection of feed processing granularity in beekeeping production.Experiment 1: Effects of different grain size diets on the digestibility of outlier worker bees.A total of 1000 one-day-old worker bees were randomly divided into 4 groups with 5replicates in each group and 50 bees in each replicate.The experiment lasted for 9 days.One was a control group and the other 3 were experimental groups.During the experiment,the control group and experimental groups were fed sucrose solution with water and sucrose: water(mass ratio)1:1.Meanwhile,the experimental groups were fed powdered diets of 100 mesh,200 mesh and 300 mesh mixed with 72% syrup solution until the 6th day,and the diets were changed every other day.On the sixth day,the remaining powder powder was taken out and continued to be fed with water and sucrose solution until the ninth day.On day 9,the hindgut of each group was dissected and the protein content was determined.Determination of protein content in the diet.The protein digestibility of each group was calculated.The results showed that the protein digestibility of bees fed 100 mesh,200 mesh and 300 mesh diets was 84.00%,84.64% and 86.96%,respectively.The protein digestibility of bees increased with the decrease of feed size.The protein digestibility of 300 mesh diet group was significantly higher than that of the other two experimental groups(P < 0.05),and there was no significant difference in the protein digestibility of 100 mesh diet group and 200 mesh diet group(P > 0.05).Experiment 2: Effects of different grain size diets on bee colony physiological functionFifteen colonies of Apis mellifera with similar population strength were randomly divided into 3 groups with 5 replicates per group and 1 colony per replicate.The experiment lasted for75 days,15 days pre-feeding period and 60 days formal experiment,respectively.During the experiment,the diet was changed every 3 days,and the feed intake of each colony was recorded to ensure the free drinking water of bees.Colony dynamics and cap sealing quantity were measured on the 12 th,24th and 36 th days of the experiment.On the 21 st day of the experiment,1-day-old new bees(1-day-old worker bees)who had just emerged from the house were labeled,and 20 unlabeled new bees were collected to measure their birth weight.The body composition,midgut enzyme activity,hemolymph physiological and biochemical indexes,antioxidant and immune capacity of labeled worker bees at 7,14 and 21 days of age were measured.The intestinal morphology of labeled 7-and 14-day-old worker bees was observed.According to statistical analysis,the results showed as follows: 1)the feed intake of bees fed 300 mesh diet experimental group was significantly higher than that of 100 mesh diet experimental group and200 mesh diet experimental group(P < 0.05),and 300 mesh diet significantly increased the colony strength of bees(P < 0.05).2)300 mesh diet significantly increased the birth weight of worker bees(P < 0.05);3)300 mesh diet significantly increased the dry matter content of worker bees at 7 days of age(P < 0.05),and increased the crude protein and ether extract contents of worker bees.4)300 mesh diet significantly increased the contents of total protein and albumin in worker bees’ hemolymph(P < 0.05).5)200 and 300 mesh diets significantly increased the thickness of midgut wall of worker bees(P < 0.05),and 300 mesh diets significantly increased the activity of amylase in midgut of worker bees(P < 0.05),but there were no significant differences in the activities of lipase and trypsin among 3 experimental groups(P > 0.05).6)The malondialdehyde content of worker bees at 7 days of age was significantly decreased by200 and 300 mesh diets(P > 0.05).7)300 mesh diet significantly increased the relative expression levels of Cu Zn SOD and Mn SOD genes in worker bees(P > 0.05).In conclusion,the results of this study showed that feed size affected intestinal protein digestibility of bees,and feeding 300 mesh diet could improve the protein digestibility of bees.At the same time,the colony feed intake and colony momentum were increased.The contents of crude protein and crude fat in bee body and the birth weight of worker bees were increased.It promoted the development of bee midgut and increased the thickness of midgut wall.The contents of total protein and albumin in worker bee hemolymph were increased and the absorption of nutrients was promoted.Feeding 100 mesh diet increased the activity of phenol oxidase and immunity of workers at 7 days of age.Feeding 300 mesh diet inhibited the content of ROS and MDA in worker bees at 21 days of age,and increased the relative expression levels of Cu Zn SOD and Mn SOD genes at 21 days of age,and improved the antioxidant capacity.Compared with 100 mesh and 200 mesh feed,300 mesh feed is more suitable for beekeeping production.