Influences of glyphosate residues and different concentrate feed proportions in dairy cow rations during early gestation on performance, blood parameters, functional properties and DNA damage of blood cells in cows and their offspring.

Maternal exposure to various stimuli can influence pre- and postnatal development of the offspring. This potential has been discussed for glyphosate (GLY), active substance in some non-selective herbicides. Accordingly, present study investigated putative effects of GLY residues in rations on cows and their offspring. Dams received either GLY-contaminated (GLY groups) or control (CON groups) rations combined with low (LC groups) or high (HC groups) concentrate feed proportions (CFP) for 16 weeks during mid- and late lactation and early gestation (59±4 days at beginning of GLY exposure; mean±SE). During this feeding trial, average daily GLY exposures of dams were 1.2 (CONLC), 1.1 (CONHC), 112.5 (GLYLC) and 130.3 (GLYHC) µg/kg body weight/d. After a depletion period (107±4 days; mean±SE) and calving, blood samples of dams and their calves were collected (5-345 min after birth) before calves were fed colostrum and analyzed for hematological and clinical-chemical traits, redox parameters, functional properties of leukocytes and DNA damage in leukocytes. No evidence for malformations of newborn calves could be collected. At parturition, most analyzed blood parameters were not affected by dietary treatment of dams during gestation. Significant GLY effects were observed for some traits, e.g. blood non-esterified fatty acids (NEFA) in calves. These deviations of GLY groups from CON groups likely resulted from strong time-dependent responses of NEFA levels within the first 105 minutes after birth and before colostrum intake (Spearman´s rank correlation R = 0.76, p<0.001). Additionally, significant GLY effects did not result in differences in measures that were beyond normally observed ranges questioning a pathological relevance. In summary, no evidence for teratogenic or other clear effects of GLY or CFP on analyzed parameters of dams and their newborn calves could be collected under applied conditions. However, detailed studies including GLY exposure during late and complete gestation period would be needed to rule out teratogenic effects.

Influences of Glyphosate Contaminations and Concentrate Feed on Performance, Blood Parameters, Blood Cell Functionality and DNA Damage Properties in Fattening Bulls.

Glyphosate (GLY), the active substance in non-selective herbicides, is often found in ruminant feed. The present feeding study aimed to investigate the effects of GLY-contaminated rations and different concentrate feed proportions (CFP) on the health of fattening German Holstein bulls. Bulls were grouped by low (LC) or high (HC) CFP with (GLYLC, GLYHC) or without GLY-contaminations (CONLC, CONHC) in their rations. Intakes (dry matter, water) and body weight were documented continuously lasting over an average range from 392.2 ± 60.4 kg to 541.2 ± 67.4 kg (mean ± SD). Blood samples collected at the trial's beginning, and after 7 and 15 weeks, were analyzed for hematological and clinical-chemical traits, functional properties of leukocytes, redox parameters and DNA damage. The average GLY exposures of 128.6 (GLYHC), 213.7 (GLYLC), 1.3 (CONHC) and 2.0 µg/kg body weight/d (CONLC) did not lead to GLY effects for most of the assessed parameters relating to animal health and performance. CFP and time displayed marked influences on most of the experimental parameters such as higher dry matter intake and average daily gain in HC compared with the LC groups. GLY effects were rather weak. However, the observed interactive effects between GLY and CFP and/or time occurring in an inconsistent manner are likely not reproducible. Finally, all animals remained clinically inconspicuous, which brings into question the physiological relevance of putative GLY effects.

No hints at glyphosate-induced ruminal dysbiosis in cows.

Glyphosate-based herbicides are among the most used non-selective herbicides worldwide and inhibit synthesis of aromatic amino acids in plants, bacteria, and fungi. Given the broad usage, controversies concerning potential effects of glyphosate on health and especially on gut microbiomes arose. For cattle, it has been proposed based on in vitro data that glyphosate has detrimental effects on the ruminal microbiome, which manifest as a specific inhibition of bacteria involved in fiber degradation and as an enrichment of specific pathogens. In the present study, glyphosate effects on the ruminal microbiome were analyzed in vivo using glyphosate contaminated feedstuffs with strong differences in dietary fiber and dietary energy content in order to reproduce the proposed detrimental glyphosate effects on the rumen microbiome. While significant impact of dietary factors on the ruminal microbiome and its products are pointed out, no adverse glyphosate effects on ruminal microbiome composition, diversity, and microbial metabolites are observed.

Effects of glyphosate residues and different concentrate feed proportions in dairy cow rations on hepatic gene expression, liver histology and biochemical blood parameters.

Glyphosate (GLY) is worldwide one of the most used active substances in non-selective herbicides. Although livestock might be orally exposed via GLY-contaminated feedstuffs, not much is known about possible hepatotoxic effects of GLY. As hepatic xenobiotic and nutrient metabolism are interlinked, toxic effects of GLY residues might be influenced by hepatic nutrient supply. Therefore, a feeding trial with lactating dairy cows was conducted to investigate effects of GLY-contaminated feedstuffs and different concentrate feed proportions (CFP) in the diets as tool for varying nutrient supply to the liver. For this, 61 German Holstein cows (207 ± 49 days in milk; mean ± standard deviation) were either fed a GLY-contaminated total mixed ration (TMR, GLY groups, mean GLY intake 122.7 µg/kg body weight/day) or control TMR (CON groups, mean GLY intake 1.2 µg/kg body weight/day) for 16 weeks. Additionally, both groups were further split into subgroups fed a lower (LC, 30% on dry matter basis) or higher (HC, 60% on dry matter basis) CFP resulting in groups CONHC (n = 16), CONLC (n = 16), GLYHC (n = 15), GLYLC (n = 14). Blood parameters aspartate aminotransferase, γ-glutamyltransferase, glutamate dehydrogenase, cholesterol, triglyceride, total protein, calcium, phosphorus, acetic acid and urea and histopathological evaluation were not influenced by GLY, whereas all mentioned parameters were at least affected by time, CFP or an interactive manner between time and CFP. Total bilirubin blood concentration was significantly influenced by an interaction between GLY and CFP with temporarily elevated concentrations in GLYHC, whereas the biological relevance remained unclear. Gene expression analysis indicated 167 CFP-responsive genes, while seven genes showed altered expression in GLY groups compared to CON groups. Since expression changes of GLY-responsive genes were low and liver-related blood parameters changed either not at all or only slightly, the tested GLY formulation was considered to have no toxic effects on the liver of dairy cows.

Functionality and DNA-damage properties of blood cells in lactating cows exposed to glyphosate contaminated feed at different feed energy levels.

Glyphosate (GL) inhibits the aromatic amino acid biosynthesis in plants and is worldwide the most used non-selective herbicide. Less is known about in vivo effects of GL contaminated feedstuffs on the health of dairy cows. The aim of this study was to examine the effects of GL residues in feed at different concentrate feed proportions (CFP) on haematology, immunological and redox parameters and on DNA-damage of blood cells in lactating dairy cows. During a 16-trial, 61 German Holstein cows (207 ± 49 d in milk; mean ± SD) were fed the same ration in week 0. Afterwards, they were assigned to either a group receiving a GL contaminated or a group receiving an uncontaminated total mixed ration (CON). Each group was subdivided into a "low concentrate" group (LC) and a "high concentrate" group (HC) with an energy content of 6.63 MJ NEL and 7.18 MJ NEL/kg dry matter, respectively. The diets were offered for ad libitum consumption. Blood samples were taken at weeks 0, 4, 8, 12 and 16. All blood samples were analysed for white and red blood cell counts. T-cell subpopulations, oxidative burst capability of leukocytes, apoptosis rate, phagocytic activity, activities of superoxide dismutase and glutathione peroxidase, the total non-enzymatic antioxidative capacity, viability and stimulation capacity of peripheral blood mononuclear cells and micronucleus- and comet assay on bovine leukocytes were measured only in week 16. The average individual GL intake of groups CON, GLLC and GLHC was 1.2 µg, 112.6 µg and 132.8 µg per kg body weight and day, respectively. GL contamination did not affect any of the tested parameters whereas CFP and time-influenced leukocytes, granulocytes, red blood cells, haemoglobin, haematocrit, mean corpuscular volume, mean corpuscular haemoglobin and CD4+ T-cells in an interactive manner characterised by a time-dependent increase in HC groups. It can be concluded that GL and GL in combination with different CFP showed no influence on any of the tested endpoints, whereas CFP and time influenced most parameters in an interactive manner.

Changes of ruminal pH, rumination activity and feeding behaviour during early lactation as affected by different energy and fibre concentrations of roughage in pluriparous dairy cows.

The aim of this study was to assess differences of ruminal pH and rumination activity between the prepartal and postpartal period of cows and to investigate changes of feeding behaviour and ruminal fermentation depending on postpartal rations with slight differences in roughage energy and fibre concentration. Therefore, 11 rumen-cannulated German Holstein cows were used from 3 weeks antepartum until 16 weeks postpartum. During the dry period, all cows received the same diet. After calving cows were assigned to two groups receiving partial mixed rations with different energy concentrations (6.1 MJ NEL/kg DM [moderate], with 18% straw on dry matter [DM] basis, group MR) or 6.5 MJ NEL/kg DM [high], with 6% straw on DM basis, group HR). In both groups, concentrates were supplied on average at 45% of total DM intake. Circadian measurements of ruminal pH, ruminal temperature and rumination activity were conducted weekly during the transition period and bi-weekly after week 4 postpartum. Throughout the postpartal period, feed intake behaviour was measured, and twice during the experiment, rumen fluid composition and net-acid-base excretion in urine were determined. Mean ruminal pH, feeding behaviour, rumination activity and rumen fluid composition did not differ between the groups, whereas group HR exhibited higher diurnal variations of pH and had a lower rumen temperature than group MR postpartum. However, these differences also occurred during the prepartal period when groups received equal rations. It was observed that ruminal pH values and the risk for subacute ruminal acidosis (SARA) were increased during postpartal period, whereby the circadian pH values showed high cow-individual variations. Overall, differences of energy and fibre concentrations in roughage did not affect the observed variables, whereby it should be noted that the number of cows was quite low in this study. Our results suggest that the ruminal pH characteristics are rather cow individual, indicating that cows presumably differ in their susceptibility to develop SARA.

The effects of energy concentration in roughage and allowance of concentrates on performance, health and energy efficiency of pluriparous dairy cows during early lactation.

The aim of this study was to investigate the effects of different energy supplies from roughage and concentrates on performance, health and energy efficiency during early lactation. For this purpose an experiment was conducted containing 64 pluriparous German Holstein cows from 3 weeks prepartum until 16 weeks postpartum. During dry period all cows received an equal dry cow ration. After calving, cows were assigned in a 2 × 2 factorial arrangement to one of four groups, receiving either a moderate (MR, 6.0 MJ NEL) or a high (HR, 6.4 MJ NEL) energy concentration in roughage and furthermore moderate (MC, 150 g/kg energy-corrected milk (ECM)) or high amounts of concentrates (HC, 250 g/kg ECM) on dry matter (DM) basis, which were allocated from an automatic feeding system. Higher allocation of concentrates resulted in an increase of DM intake at expense of roughage intake. HC cows had a higher milk yield than MC cows, whereas ECM was higher in HR cows due to a decrease of milk fat yield in MR groups. Energy balance and body condition score were elevated in HC cows, but no differences occurred in development of subclinical ketosis. Furthermore, energy efficiency variables were lower in HC groups because the greater energy intake was not associated with a considerable elevation of milk yield. Consistency of faeces did not indicate digestive disorders in any of the treatment groups although the faecal manure score was significantly lower in HR groups. Our results underline the importance of a high energy uptake from roughage, which can contribute to an adequate performance and beneficial efficiency, especially at lower amounts of concentrates in ration. Feeding concentrates on an average amount of 9.4 kg/d compared to 6.4 kg/d on DM basis improved the energy balance in our trial, but without consequences for metabolic blood variables and general health of the cows.

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

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, ß-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 CONLC, CONHC, GLLC and GLHC 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.