Impact of glyphosate residues in sow diets on neonatal piglets: tail kinks, stillborn and diarrhoea

Abstract

Among the applications, glyphosate-based herbicides are used for pre-harvest crop desiccation and weed management in glyphosate resistant crops. Due to these applications glyphosate residues have been found in feedstuff for conventional livestock. Besides its herbicidal property, glyphosate has documented mineral chelating and antimicrobial properties. Previous studies have found glyphosate residuals in animal organs, and glyphosate may cause adverse effects in animals during the embryonic or neonatal period. The present study has two endpoints; (1) whether glyphosate concentration in the diets fed to sows during early gestation, was associated with the frequency of congenital tail kinks and stillborn piglets, and (2) whether the glyphosate concentration in diets fed to lactating sows, is associated with the frequency of diarrhoea in neonatal piglets. The concentration of glyphosate in 78 gestation diets obtained from seven Danish conventional sow herds ranged from 0.08 to 1.52 mg/kg dry matter (DM) and in 34 lactation diets from 0.06 to 0.87 mg/kg DM. When correcting for an average DM content of 88.3% in gestation diets and 89.0% in lactation diets the concentration of glyphosate ranged from 0.07 to 1.34 and 0.05 to 0.77 mg/kg feed, respectively. In the first study, 28,336 docked tails from 2 to 4-day-old piglets were assessed for congenital tail kinks and the number of kinky tails per herd per week was linked to the glyphosate concentration in sow diets during week 1 to 6 of gestation. Percentage of kinky tails and stillborn piglets ranged from 0 to 2.60% and 0.7 to 3.2% per week, respectively. No associations between the glyphosate concentration in sow gestation diets and the frequency of kinky tails or stillborn piglets were found. In the second study, faeces consistency of 5,526 piglets from 386 litters was linked to the glyphosate concentration in sow lactation diets. A proportion of 0.15 of the 0- to 5-day-old piglets had diarrhoea. No association was found between the concentration of glyphosate in sow lactation diets and the frequency of diarrhoea in neonatal piglets.