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Nutritive value and multi-mycotoxin occurrence in feeds and milk of dairy cattle

Amal Mannai, Cristina Juan, Jordi Manes, Hichem Ben Salem

Abstract

Context. The contamination of feedstuffs with multi-mycotoxins and their transfer to milk is an important concern as it can affect the health of both animals and humans. Aims. This study determined the nutrient composition and quantified the mycotoxins present in dairy feedstuffs and in cow’s milk. Methods. Samples of feedstuffs and milk were collected from 11 dairy farms in northern Tunisia for physicochemical composition and mycotoxin analyses. The extraction of mycotoxins was carried out by the QuEChERS procedure and the presence of 26 mycotoxins was checked using liquid or gas chromatography with tandem mass spectrometry (LC-MS / MS and GC-MS / MS). Key results. Nutrient contents differ among feedstuffs (p < 0.05). The pH values of oat, ryegrass and pulp silages varied from 4.6 to 5.3. Dry matter (DM) content was highest for concentrate feeds and hay (90 and 86% DM, respectively). Crude protein (CP) content was highest in concentrate feeds (15.8 % DM). The neutral detergent fiber (NDF), acid detergent fiber (ADF) and lignin (ADL) contents were highest in green grass, hay, and silage. Eight Fusarium mycotoxins, enniatins (ENA1, ENB, ENB1), beauvericine (BEA), HT-2 toxin (HT-2), deoxynivalenol (DON), 15-Acetyldeoxynivalenol (15-ADON), Fumonisin B2 (FB2) and one Alternaria mycotoxin tentoxin (TENT) were detected at low concentrations. There was a significant difference in the levels of contamination by ENB between the samples of forages and concentrate feeds (p < 0.05). The ENs (ENA1, ENB, ENB1) were the most frequently detected combination of mycotoxins. Milk analysis for fat, CP, lactose and dehydrated dry extract averaged 3.49, 3.10, 4.71, and 8.77%, respectively; urea concentration was of 34.01 mg/dl, milk pH was 6.5, and a somatic cell count of 1168.63 103 cells/mL was found. Most milk samples (82%) were contaminated with ENB. Conclusions. The levels of mycotoxin contamination in feedstuffs and milk were low and do not present a risk for dairy cattle and consumer health. Implication. Mycotoxins in feedstuffs and milk should be regularly analysed to make sure that quality and safety standards are met.

AN23206  Accepted 22 July 2024

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