The Effect Of Vitamin D3 On Round Brachionus Rotundiformis And Brachionus Calyciflorus Population And Morphological Changes

As rotifers are the most commonly used open bait in the breeding process of aquaculture economic animals,it is of great practical importance to efficiently cultivate rotifers that can meet the nutritional needs of aquaculture economic animal seedlings.Vitamin D3(also known as cholecalciferol)is a fat-soluble vitamin that accelerates the absorption of calcium and phosphorus and promotes the growth and development of aquatic animals.Research on vitamin D3 has focused on vertebrates,but its effects on individual growth and population changes in rotifers have not been reported.Brachionus rotundiformis and Brachionus calyciflorus are the most commonly used rotifer strains in marine and freshwater aquatic economy animal nurseries,respectively.In this study,we investigated the effects of different vitamin additives on the population changes of Brachionus rotundiformis and Brachionus calyciflorus,which are commonly used in the production of rotifers.Finally,the effects of vitamin D3 on the population density,egg-holding rate,population growth rate,survival rate and survival time of the two rotifers were further investigated.The specific results are as follows:1.The effect of vitamin D3 on the population and morphological changes of Brachionus rotundiformis was greater than that of vitamin B12,vitamin E and vitamin A.In this study,it was found that the addition of vitamin B12 at a concentration of 0.2 μg/ml or vitamin D3 at a concentration of 0.1 μg/ml to the culture water at 25 ℃ had a certain effect on the population growth of Brachionus rotundiformis,and vitamin D3 In addition,the addition of vitamin E at 0.01 μg/ml had no significant effect on the growth of rotifer populations;the addition of vitamin A at 1 μg/ml had an inhibitory effect on the growth of rotifer populations.When Brachionus rotundiformis were fortified with vitamin D3 at a concentration of 0.1 μg/ml in a water body with a salinity of 1.02,the population growth rates were 0.06,0.10 and 0.17 in the first three days,respectively,which were higher than the control and other vitamin-added groups.In addition,the population supplemented with 0.1 μg/ml of vitamin D3 showed a 41% increase in egg-holding rate on the third day of incubation,which was higher than that of the control and other vitamin-added groups;the length and width of egg-holding rotifers increased by 10.0%and 7.4%,respectively,compared to the control,while the length and width of non-egg-holding rotifers increased by 14.8% and 10.2%,respectively,compared to the control.2.Vitamin D3 supplementation promoted individual growth of Brachionus rotundiformis and Brachionus calyciflorus The individual dorsal carapace length and carapace width were significantly higher in Brachionus rotundiformis and Brachionus calyciflorus culture after the addition of vitamin D3 than in the non-addition group.Individuals in the Brachionus rotundiformis culture with a concentration of 0.1 μg/ml of vitamin D3 reached their maximum growth on day 3,when their perithecial length and width were 127.3 ± 2.7 μm and 121.4 ± 1.9 μm,respectively,higher than those in the non-addition group at 121.5 ± 1.2 μm and 112.6 ± 1.4 μm.In the Brachionus calyciflorus culture with a concentration of 0.1 μg/ml of vitamin D3,individuals grew significantly more than those in the non-addition group at 127.3 ± 2.7 μm and 121.4 ± 1.9 μm,respectively.In addition,the addition of 0.1 μg/ml of vitamin D3 had a greater effect on the size of the non-oviposition rotifers after 0.1 μg/ml of vitamin D3.After four days of vitamin D3 fortification,the growth rate of perithecial length and perithecial width of non-oviparous Brachionus calyciflorus was 12.6% and 7.9% higher than that of oviparous Brachionus calyciflorus.3.Vitamin D3 supplementation promoted population growth and survival of both round and calyx rotifers.The population density,egg-holding rate and population growth rate of Brachionus rotundiformis and Brachionus calyciflorus were significantly higher than those of the non-addition group after the addition of vitamin D3 in culture,and the optimum concentration of vitamin D3 was 0.1 μg/ml.The population density,egg-holding rate and population growth rate of Brachionus rotundiformis were 214 ind./ml,39 % and0.65,respectively,higher than those of the non-addition group,The population density,egg-holding rate and population growth rate of rotifers were 132 ind./ml,32 % and 0.39 for Brachionus calyciflorus at a concentration of 0.1 μg/ml of vitamin D3,respectively,which was higher than that of 103 ind./ml,23 % and 0.27 for the unsupplemented group.Vitamin D3 supplementation also increased the survival time of rotifers: the mean survival time of Brachionus calyciflorus at 0.1 μg/ml was 216 h longer than that of the unsupplemented group,and the mean survival time of Brachionus rotundiformis at 174 h was 16 h longer than that of the unsupplemented group at 0.1 μg/ml.The rotifer had a faster population growth rate than Brachionus calyciflorus.