Effects of glyphosate residues and different concentrate feed proportions on performance, energy metabolism and health characteristics in lactating dairy cows

Abstract

The aim of this study was to examine the influence of glyphosate (GL) residues in feedstuffs on performance, energy balance and health-related characteristics of lactating dairy cows fed diets with different concentrate feed proportions. After an adaption period, 64 German Holstein cows (207 ± 49 d in milk; mean ± SD) were assigned to either groups receiving a GL contaminated total mixed ration (TMR) (GL groups) or an uncontaminated TMR (CON groups) during a 16 weeks trial. Contaminated feedstuffs used were legally GL-treated peas and wheat (straw and grain). GL and CON groups were subdivided into a "low concentrate" group (LC) fed on dry matter (DM) basis of 21% maize silage, 42% grass silage, 7% straw and 30% concentrate and a "high concentrate" group (HC) composed of 11% maize silage, 22% grass silage, 7% straw and 60% concentrate for ad libitum consumption. Body condition score, body weight, DM intake and milk performance parameters were recorded. In blood serum, β-hydroxybutyrate (BHB), non-esterified fatty acids (NEFA) and glucose were measured and energy balance was calculated. Milk was analysed for GL residues. At week 0, 7 and 15, general health status was evaluated by a modified clinical score. The average individual GL intake amounted for Groups CON, CON, GL and GL to 0.8, 0.8, 73.8 and 84.5 mg/d, respectively. No GL residues were detected in milk. GL contamination did not affect body condition score, body weight, DM intake, nutrient digestibility, net energy intake, net energy balance or BHB, glucose, NEFA and milk performance parameters; whereas concentrate feed proportion and time did affect most parameters. The clinical examination showed no adverse effect of GL-contaminated feedstuffs on cows' health condition. In the present study, GL-contaminated feedstuffs showed no influence on performance and energy balance of lactating dairy cows, irrespective of feed concentrate proportion.

Minimum Inhibitory Concentration of Glyphosate and of a Glyphosate-Containing Herbicide Formulation for Escherichia coli Isolates – Differences Between Pathogenicand Non-pathogenic Isolates and Between Host Species

“…Little data is available about the amount of residues in feed, however, imported soybean meal seems to be the main source (von Soosten et al, 2016). Glyphosate has been found in poultry and cattle feed in Germany (Shehata et al, 2014) and in a study in cattle feed (Schnabel et al, 2017).…”

Effect of a glyphosate-containing herbicide on Escherichia coli and Salmonella ser. Typhimurium in an in vitro rumen simulation system

“…Schnabel et al determined a daily glyphosate intake of up to 84.5 mg per day for lactating dairy cows [23]. Rounding this value to 100 mg per day and taking the rumen content volume (about 100 L) into account, we established a daily glyphosate exposure level of 1 mg/L rumen content.…”

“…Shehata et al estimated 0.4–0.9 mg/kg in poultry and cattle feed in Germany [22]. In order to identify how much glyphosate remains in cattle feed after the harvest, Schnabel et al treated wheat and peas with the formulation Roundup® Record according to the legal European Union (EU) regulations and determined an intake of 73.8 or 84.5 mg glyphosate per cow per day, depending on the proportion of concentrate in the total mixed ration [23]. A small amount of glyphosate is potentially degraded to aminomethylphosphonic acid (AMPA) in the rumen [24].…”

“…For this, the in vitro effects of a glyphosate-containing formulation on growth, survival, and resistance of E. coli and Salmonella ser. Typhimurium at a worst-case glyphosate concentration [23] were investigated using the "Rumen Simulation Technique" (RUSITEC) [37].…”

Indirect Effects of the Herbicide Glyphosate on Plant, Animal and Human Health Through its Effects on Microbial Communities

“…Glyphosate residues in breast milk have been reported unofficially (Honeycutt and Rowlands, 2014), but not in refereed journals (Bus, 2015;Ehling and Reddy, 2015;Steinborn et al, 2016). Glyphosate has rarely been detected in cow milk, including formula milk, but not above the MRL of 0.05 mg/L milk (Schnabel et al, 2017;van Eenennaam and Young, 2017;von Soosten et al, 2016). Van Eenennaam and Young (2017) found little evidence of accumulation of glyphosate in animal tissues except in kidneys and liver.…”