Apparent digestibility of lipids and fatty acids by Apis mellifera (L.): a comparative study of different bee pollen types collected in Argentina

LEDESMA MF ; LÓPEZ, G.; GRANDINETTI G.; TOURN E.; FERNÁNDEZ LA.; REYNALDI FJ,

Santiago de Chile

Congreso; 48° APIMONDIA Congress; 2023

APIMONDIA

Pollen is the primary natural source of proteins and lipids for Apis mellifera and it plays an essential role in bee nutrition. In this study we measured in vitro apparent digestibility of eight bee pollen (Brassicaceae, Eucalyptus sp., Rhamnaceae, Prosopis sp., Carduus sp., Schinus sp., Pinus sp. [hand collected] and Prunus sp.) with focus in lipids and fatty acids profiles. Bee pollen were collected in four locations in the southwest of Buenos Aires province. Newly hatched bees were randomly placed in cages (with 50 bees per cage) at 34°C and 60% relative humidity. Pollen was provided fresh with the addition of TiO2 as inert marker (0.1 % w/w based on dry mass basis). Faeces were collected by dissecting the insect´s rectum after 14 days. We compared lipid content and fatty acid profiles of bee pollen with that of the faeces in order to obtain the nutrient apparent digestibility. Lipid content was quantified by Goldfish method while fatty acid profile by gas chromatography. Statistically significant differences were observed in bee pollen apparent digestibility. Carduus sp. (71.72% ±5.3) had the highest apparent digestibility values, and Brassicaceae (60.92% ±10.05) and Pinus sp. (5.39% ±41.3) had the lowest ones. Faeces had a higher content of total lipids (30.27% ±17.8) than bee pollen (3.38% ±1,9). Mean lipid apparent digestibility was 95.30% ±5.5, (highest score for Brassicaceae( 98.24%) and lowest for Pinus sp. (81.94%) The main fatty acids detected in faeces were oleic (C18:1), linoleic (C18:2), palmitic (C16:0) and linolenic (C18:3) acid, similar results were detected in bee pollen. In general, faeces had C18:1 as the main fatty acid and had lower concentration of C16:0, C18:3 and C18:2 than their respective pollens. Apparent fatty acid digestibility was 84,79% for C18:1, 88,70% for C18:2, 95,38% for C16:0 and 89,32% for C18:3. We concluded that lipids and their fatty acids profiles undergo changes as they pass through digestive tract. Lipids had apparent digestibility near 100% showing that they are highly digestible nutrient for honeybee. These results could be used as a starting point for improving beekeeping practices in order to take advantages of different types of pollens.