Assessment of veterinary antibiotics from animal manure-amended soil to growing alfalfa, alfalfa silage, and milk

Rongcai Huang; Zitai Guo; Shengtao Gao; Lu Ma; Jianchu Xu; Zhongtang Yu; Dengpan Bu

doi:10.1016/j.ecoenv.2021.112699

Assessment of veterinary antibiotics from animal manure-amended soil to growing alfalfa, alfalfa silage, and milk

Ecotoxicol Environ Saf. 2021 Aug 25:224:112699. doi: 10.1016/j.ecoenv.2021.112699. Online ahead of print.

Authors

Rongcai Huang¹, Zitai Guo¹, Shengtao Gao¹, Lu Ma¹, Jianchu Xu², Zhongtang Yu³, Dengpan Bu⁴

Affiliations

¹ State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
² State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China; World Agroforestry Center, East and Central Asia, Kunming 650201, China; Honghe Center for Mountain Futures, Kunming Institute of Botany, Chinese Academy of Sciences, Honghe County 654400, Yunnan, China.
³ Department of Animal Sciences, The Ohio State University, Columbus, OH 43210, USA.
⁴ State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China; CAAS-ICRAF Joint Lab on Agroforestry and Sustainable Animal Husbandry, World Agroforestry Centre, East and Central Asia, Beijing 100081, China; Hunan Co-Innovation Center of Animal Production Safety, Changsha, Hunan 410128, China. Electronic address: budengpan@caas.cn.

PMID: 34454356
DOI: 10.1016/j.ecoenv.2021.112699

Abstract

Using animal manure as organic fertilizer to grow fodder crops is causing public health concerns because animal manure is the major reservoir of veterinary antibiotics. In this study, we used a mathematical model to estimate the risk of human exposure to veterinary antibiotics when using swine manure as organic fertilizer to grow alfalfa (Medicago sativa L.). Alfalfa was planted in a greenhouse and fertilized with swine manure spiked with oxytetracycline (OTC, at 0, 150, and 1500 mg/kg of manure), ofloxacin (OFL, at 0, 15, and 150 mg/kg), or sulfamonomethoxine (SMM, at 0, 5, 15 and 150 mg/kg). Alfalfa was harvested at the budding stage and ensiled for 60 days. Results showed that OTC and OFL could be detected in the alfalfa root, stem, and leaf with a concentration ranging from 8.85 to 59.17 μg OTC /kg and from 1.50 to 4.10 μg OFL/kg dry matter, but SMM could only be detected in the root ranging from 29.10 to 63.75 μg/kg dry matter. The ensiling for 60 days decreased the OFL concentration by 68.7% but only slightly decreased the OTC concentration. The maximum daily exposures of humans to OTC and OFL through liquid milk consumption were estimated to be 5.84E-8 and 1.63E-8 μg, respectively, both of which are well below the intake levels of OTC (72 μg) and OFL (54 μg) mandated by the European Union. The results of the present study indicate that using swine manure as organic fertilizer to grow alfalfa poses a limited risk for human exposure to veterinary antibiotics through the consumption of liquid milk.

Keywords: Alfalfa; Exposure assessment; Milk; Organic fertilizer; Veterinary antibiotic.