Outbreak of aflatoxicosis in a dairy herd induced depletion in milk yield and high abortion rate in Pakistan.

This case report investigated the outbreak of aflatoxicosis in a dairy herd in Pakistan, which resulted in 30 abortions of 40 confirmed (75%) pregnant cows in a period of 35 days and in 18.8% depression of farm average milk production for the entire herd. The analysis of the concentrate feed of the total mixed ration (TMR), using enzyme-linked immunosorbent assay (ELISA) procedures from two different local laboratories, indicated concentrations of 60 µg/kg dry matter (DM) of aflatoxin B1 (AFB1) and 100 µg/kg DM of total aflatoxins (AFs: sum of B1, B2, G1 and G2). Subsequently, a confirmatory analysis with a more sensitive and validated multi-metabolite liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was performed. This analysis detected a concentration of total AFs in the TMR of 166 µg/kg DM ± 3.5 (AFB1:134, AFB2:17.4 and AFM1:14.9 µg/kg DM). The concentrate feed (55% of the TMR DM) was confirmed as a source of contamination, presenting a concentration >29 times higher than the EU-maximum limit value (5.68 µg/kg DM). Additionally, the multi-mycotoxin analysis evidenced the co-occurrence of 81 other toxic and potentially toxic fungal metabolites in the fed TMR. After replacing the contaminated concentrate feed with feedstuffs of the same formulation but from a new charge of ingredients, the abortion episodes ceased, and milk production increased significantly. In conclusion, the data of this case report suggest that AFs may be associated with pregnancy losses in dairy cattle and milk production depression. From the public health perspective, the data also indicate the need for a more careful examination of dairy animal feed in Pakistan. Since the high concentration of AFB1 detected in feed and considering the literature-reported transfer rates (1-6%) of this toxin to AFM1 (carcinogen for humans) in milk, the milk produced during the outbreak period is expected to be contaminated with AFM1, which raises public health concerns.

Duration of Zearalenone Exposure Has Implications on Health Parameters of Lactating Cows.

There is a limited research focus on evaluating the detrimental effects of prolonged zearalenone (ZEN) intake on dairy cows' health under controlled conditions. This experiment was conducted to evaluate whether the length of exposure to a ZEN-contaminated total mixed ration (TMR) at a level of 9.45 mg per day can negatively influence animal health parameters, such as milk composition, rumen and fecal fermentation, and the chewing activity of lactating dairy cows. For this experiment, we used 18 lactating Simmental cows that were fed a diet of 60% forage and 40% concentrate (on dry matter basis) for 26 consecutive days. The first 4 days were for adaptation prior to the first sampling day (day 0). The sampling events took place on day 0 (baseline) without ZEN, followed by day 1, day 7, day 14, and day 21 (with toxin). Dry matter intake (DMI) and ruminating chews per minute increased on the third week of ZEN inclusion; meanwhile, ruminating, eating, and drinking times were not affected. Most milk composition variables were also unaffected. Rumen fluid osmolality increased on day 21 and total short-chain fatty acids (SCFA) of ruminal fluid decreased on day 7. Fecal SCFA increased on day 21 and the acetate-to-propionate ratio increased from day 1 onwards, showing the influence of toxin intake. Animal health parameters, like heart rate, respiratory rate, and body temperature, were negatively influenced by ZEN intake, all increasing consistently on days 4 and 6, 9 and 12, and 16 and 18, respectively. The liver enzyme glutamate dehydrogenase decreased in response to ZEN intake on day 7. A total daily ZEN intake at the level of 9.45 mg did not show detrimental effects on DMI. Nevertheless, certain health parameters were negatively affected, including body temperature, respiratory rate, and heart rate, starting from the 7th day of ZEN intake, with additional signs of possible loss of water balance on the last sampling day.

Dietary carbohydrate sources differently prime the microbial ecosystem but not the epithelial gene expression profile along the complete gut of young calves.

BACKGROUND: Recent data indicated similar growth performance of young calves fed solely high-quality hay instead of a starter diet based on starchy ingredients. Yet, providing exclusively such distinct carbohydrate sources during early life might specifically prime the microbiota and gene expression along the gut of young calves, which remains to be explored. We investigated the effects of starter diets differing in carbohydrate composition, that is medium- or high-quality hay and without or with 70% concentrate supplementation (on fresh matter basis), across the gastrointestinal tract (GIT) of weaned Holstein calves (100 ± 4 days of age) using 16 S rRNA gene sequencing and analyses of short-chain fatty acids and host epithelial gene expressions. RESULTS: The concentrate supplementation drastically decreased microbial diversity throughout the gut, which was also true to a much lesser extent for high-quality hay when compared to medium-quality hay in the foregut. Similarly, the factor concentrate strongly shaped the diet-associated common core microbiota, which was substantially more uniform along the gut with concentrate supplementation. The fermentation profile shifted towards less acetate but more propionate with concentrate supplementation in almost all gut sections, corresponding with higher abundances of starch-utilizing bacteria, while major fibrolytic clusters declined. Noteworthy, the n-butyrate proportion decreased in the rumen and increased in the colon with concentrate, showing an opposite, gut site-dependent effect. Both dietary factors modestly influenced the host epithelial gene expression. CONCLUSIONS: Concentrate supplementation clearly primed the microbial ecosystem on a starch-targeted fermentation with characteristic genera occupying this niche along the entire GIT of calves, whereas the microbial differentiation due to hay quality was less distinct. Overall, changes in the microbial ecosystem were only marginally reflected in the targeted transcriptional profile of the host epithelium.

Correction: Penagos-Tabares et al. Mixtures of Mycotoxins, Phytoestrogens, and Other Secondary Metabolites in Whole-Plant Corn Silages and Total Mixed Rations of Dairy Farms in Central and Northern Mexico. Toxins 2023, 15, 153.

In the original publication [...].

Elucidating the factors and consequences of the severity of rumen acidosis in first-lactation Holstein cows during transition and early lactation.

First-lactation cows are particularly prone to subacute ruminal acidosis (SARA) during transition. Besides common risk factors of SARA, such as feeding of starch-rich diets, an individual severity of SARA in cows has been recently evidenced. Yet, the factors that play a role in SARA severity have not been elucidated. The main goal of this research was to evaluate the factors of SARA severity in first-lactation cows during transition and early lactation, which go beyond high-grain feeding, and to explore their impact on behavior, health, and fermentation in the rumen and hindgut. Twenty-four first-lactation Holstein cows with the same feeding regime were used starting from 3 wk before the expected calving day until 10 wk postpartum. Cows received a close-up diet (32% concentrate) until calving and were then transitioned to a lactation diet (60% concentrate) within 1 week. The SARA severity was assessed by cluster analysis of several rumen pH metrics, which revealed exceptionally longer and more severe SARA in cows denominated as high (n = 9), as compared to moderate (n = 9) and low (n = 6) SARA severity cows (P < 0.01). The logistic analysis showed that the length of close-up feeding, age at parturition, and the level of dry matter intake (DMI) were the main factors that influenced the cows' odds for high SARA severity (each P ≤ 0.01). Moreover, the ANOVA hinted differences in the metabolic activity of the ruminal microbiome to promote SARA severity, as indicated by highest ruminal propionate proportions (P = 0.05) in high SARA severity cows, also with similar DMI. The distinct SARA severity was marginally reflected in behavior and there were no effects of SARA severity or high-grain feeding on blood inflammation markers, which peaked at parturition regardless of SARA severity (P < 0.01). Still, ongoing high-grain feeding increased liver enzyme concentrations from 6 wk postpartum on, compared to weeks before (P < 0.01), yet irrespectively of SARA severity. In conclusion, first-lactation cows differed in SARA severity under the same feeding regime, which was ascribed to management factors and differences in ruminal fermentation. Further research is warranted to validate these findings and to understand the mechanisms behind differences in the metabolic function of rumen microbiome, in particular in terms of evaluating markers for various SARA severity, as well as to evaluate potential long-term effects on health, performance, fertility, and longevity of dairy cows.

The present study reports a high variation of severity of subacute rumen acidosis in first-lactation dairy cows with the same feeding regimen close to parturition and until 10 weeks after parturition. Six significant factors influencing this severity were identified, including in particular length of close-up period, age at parturition, and dry matter intake. Therefore, management factors seem to play a key role for the development of a severe subacute rumen acidosis. Cows with high severity showed marginally altered behavior but distinct rumen fermentation patterns compared to cows with low severity, suggesting also a key role of the ruminal microbiome for subacute rumen acidosis risk in cows. The higher severity was not associated with systemic inflammation and all cows remained healthy.

Integrated microbiota-host-metabolome approaches reveal adaptive ruminal changes to prolonged high-grain feeding and phytogenic supplementation in cattle.

Diets rich in readily fermentable carbohydrates primarily impact microbial composition and activity, but can also impair the ruminal epithelium barrier function. By combining microbiota, metabolome, and gene expression analysis, we evaluated the impact of feeding a 65% concentrate diet for 4 weeks, with or without a phytogenic feed additive (PFA), on the rumen ecosystem of cattle. The breaking point for rumen health seemed to be the second week of high grain (HG) diet, with a dysbiosis characterized by reduced alpha diversity. While we did not find changes in histological evaluations, genes related with epithelial proliferation (IGF-1, IGF-1R, EGFR, and TBP) and ZO-1 were affected by the HG feeding. Integrative analyses allowed us to define the main drivers of difference for the rumen ecosystem in response to a HG diet, identified as ZO-1, MyD88, and genus Prevotella 1. PFA supplementation reduced the concentration of potentially harmful compounds in the rumen (e.g. dopamine and 5-aminovaleric acid) and increased the tolerance of the epithelium toward the microbiota by altering the expression of TLR-2, IL-6, and IL-10. The particle-associated rumen liquid microbiota showed a quicker adaptation potential to prolonged HG feeding compared to the other microenvironments investigated, especially by the end of the experiment.

Comparison of LC-MS-based methods for the determination of carboxylic acids in animal matrices.

Carboxylic acids (CAs) are key players in human and animal metabolism. As they are hardly retained under reversed-phase liquid chromatography (RP-LC) conditions in their native form, derivatization is an option to make them accessible to RP-LC and simultaneously increase their response for mass spectrometric detection. In this work, two RP-LC tandem mass spectrometry-based methods using aniline or 3-nitrophenylhydrazine (3-NPH) as derivatization agents were compared with respect to several factors including completeness of derivatization, apparent recoveries (RAs) in both cow feces and ruminal fluid, and concentrations obtained in feces and ruminal fluid of cows. Anion exchange chromatography coupled to high-resolution mass spectrometry (AIC-HR-MS) served as reference method. Derivatization efficiencies were close to 100% for 3-NPH derivatization but variable (20-100%) and different in solvent solutions and matrix extracts for aniline derivatization. Likewise, average RAs of 13C-labeled short-chain fatty acids as internal standards were around 100% for 3-NPH derivatization but only 45% for aniline derivatization. Quantification of CAs in feces and ruminal fluid of cows initially fed a forage-only diet and then transitioned to a 65% high-grain diet which yielded similar concentrations for 3-NPH derivatization and AIC-HR-MS, but concentrations determined by aniline derivatization were on average five times lower. For these reasons, derivatization with aniline is not recommended for the quantitative analysis of CAs in animal samples.

Buffering Capacity of Various Commercial and Homemade Foods in the Context of Gastric Canine Digestion.

The buffering capacity (BC) of food may act as a key regulatory parameter of canine gastric digestion by influencing the activity of gastric enzymes, the solubility of dietary ingredients, the gastric breakdown of food nutrients, and, subsequently, the absorption of nutrients. To analyse a possible effect of food on gastric pH, the BC of wet, dry, and homemade dog food was quantified via an acid titration method until a pH under 2 was achieved. Wet food had the highest BC; between dry and homemade food, there was no significant difference. Using multiple regression analyses, we were able to establish associations between the nutrient composition and the BC of the dog food. Crude protein content was the most important factor that influenced the BC and HCl use per gram of dry matter (DM) (p < 0.001), whereas the initial pH only tended to have an influence. The ash content also tended to affect the used HCl per gram of DM, and the DM content had a significant (p < 0.05) influence on the BC per gram of DM. The excessively high ash content found in wet food could be a risk factor for gastric dilatation-volvulus syndrome because it could lead to an insufficient pH drop in the stomach. Our data indicate large differences in the BC of typical dog food; so, estimating the BC using the equations developed herein could help to design individualized dog diets, in particular for dogs with health problems such as gastric hypoacidity, gastric reflux, or gastritis. However, more research about the influence of dog-food BC on gastric pH in vivo is needed.

Changes in the nutrient profile and the load of mycotoxins, phytoestrogens, and pesticides in horse pastures during spring and summer in Austria.

Pastures are used for grazing and the production of conserved roughage in horses. Yet, the nutritional profile of the forage varies from spring to late summer, affecting equine nutrient supply and health. In addition, environmental factors may also favor plant contaminants such as mycotoxins. This study aimed to determine the nutritional profile and contaminant load of selected horse pastures from early spring till late summer. The nutrient composition (main macronutrients, macro elements and trace elements), as well as mycotoxins, metabolites, pesticides, and plant-derived compounds of seven horse pastures were analyzed. Each pasture was sampled three times and the samples were categorized according to the status of the pasture plants: ear emergence, early- till full bloom, and drought-damaged vegetation. Drought-damaged pastures demonstrated a rise in the acid to neutral detergent fiber ratio, calcium, iron, and magnesium but lower potassium contents. Mycotoxins and other contaminants were found in the pastures including 64 fungal compounds (ergot alkaloids (13) and metabolites from Fusarium (21), Aspergillus (2), Penicillium (8), Alternaria (8) and other fungal species (12), one bacterial metabolite (cereulide), twelve plant metabolites (including eight phytoestrogens and three cyanogenic glycosides (linamarin, lotaustralin and prunasin)), 11 nonspecific metabolites and six pesticides. Fusarium metabolites showed the highest concentrations among the fungal metabolites and drought-induced stress increased the contamination levels (range: 123-3873 µg/kg DM). In conclusion, there was a dominant effect of the developmental stages of the plants, botanical composition of the pastures and weather conditions on the nutritional composition and presence of contaminants on pastures.

Effects of particle size reduction of meadow hay on feed intake, performance, and apparent total tract nutrient digestibility in dairy cows.

Forage-based diets are encouraged in organic dairy cattle production as this can increase the net human food supply, but their voluminous nature can limit dry matter intake (DMI) and performance. This study investigates the effects of a substantial particle size reduction of hay on dairy cows' feed intake, performance, and body characteristics, as well as on apparent total tract digestibility (ATTD). Eighteen lactating Holstein cows were allocated to two balanced feeding groups. The control group received long stem hay with a conventional particle size (CON), the experimental group received chopped hay (RED). Both groups were supplemented with concentrates (3.6 kg/d, DM basis). After 14 adaptation days, data were collected for 20 consecutive days. A covariate period of 21 days preceded the experimental feeding period. Particles retained on the 19-, 8- and 4-mm screens and on the pan of the Penn State Particle Separator accounted for 21%, 20%, 20% and 39% of the RED hay. CON hay consisted of 72% large particles, followed by 8%, 7% and 13% retained on the other screens. Average DMI levels of cows in the CON group reached 20.8 kg/d, with a nonsignificant increase (+1.05 kg/d) in the RED group (p = 0.28). Intakes of both NFC (+0.65 kg/d, p = 0.01) and CP (+0.28 kg/d, p = 0.05) were significantly greater in the RED group, resulting in a slightly increased milk yield (+0.8 kg energy corrected milk/d) (p = 0.45), likely because the ATTD decreased significantly when feeding RED hay. No impact was observed on energy balance (103.7 vs 103.9%, p = 0.95), feed conversion efficiency (kg ECM/kg DMI), or N use efficiency. Overall, the results indicate increases in intake of NFC and CP in the RED group when feeding a hay-based (>83%, DM basis) diet, but also a decrease in nutrient digestibility, likely due to increased passage rate, potentially because of the high fraction of hay particles < 4 mm. In conclusion, hay-based rations with a lower proportion of fine particles should be tested to exploit the potential of particle size reduction in terms of improving hay use efficiency.

Magnesium in dairy cattle nutrition: A meta-analysis on magnesium absorption in dairy cattle and assessment of simple solubility tests to predict magnesium availability from supplemental sources.

Supplemental Mg sources differ in bioavailability, and solubility is one of the determining factors. We explored whether and which in vitro solubility tests could reliably differentiate the quality of supplemental Mg sources. In experiment 1, we compared 3 chemical methods using an acetic acid solution (50 mL/L, termed vinegar test), a 1 M ammonium nitrate solution, and an artificial rumen buffer fluid without rumen microbiota. The Mg solubility results suggested the vinegar test was the best method due to its robustness, simplicity, and reproducibility. In experiment 2, we validated the reliability of the vinegar test using 4 MgO sources from experiment 1 and 12 new MgO sources plus a laboratory-grade MgO as a standard. Accordingly, we repeated the vinegar test with short (0.5 h) and long (3.0 h) incubation times on these sources and then conducted ruminal incubations in 24-h batch culture experiments. The repeated vinegar test resulted in similar results as in experiment 1. Linear regression across both experiments showed the soluble Mg content (g/kg) = 44.46 (±2.55) × pH - 142.9 (±14.9), root mean square error (RMSE) = 10.2, P slope <0.001, and concordance correlation coefficient (CCC) = 0.953. The predictable pH range was from 4 to 6. The equation cannot be applied to low-alkaline sources such as Mg sulfate, Mg acetate, or a group of MgO with exceptionally high alkaline properties showing a cluster of pH above 8.5. Solubility of the MgO sources in the vinegar test ranged from 5 to 35%, whereas the 24-h ruminal incubations led to more solubility (15-70%). Nevertheless, the differences among most MgO sources were parallel to the data from the in vitro rumen solubility. Next, we performed a meta-analysis of published studies (21 studies, 94 treatments) to assess the true Mg absorption in vivo and potential factors affecting Mg absorption in dairy cows. It appeared that on average dairy cows absorbed about 20% of the Mg intake (range 10-40%), regardless of their lactation status. We revealed a new strategy to predict Mg absorption relative to dietary K as follows: true Mg absorption (g/d) = 0.3395 (±0.025, P < 0.001) × Mg intake (g/d) - 1.9273 (±1.16, P = 0.11) when dietary K ≤20 g/kg DM, and 0.154 (±1.06, P = 0.05) + 0.209 (±0.026, P < 0.001) × Mg intake (g/d) when dietary K >20 g/kg DM (RMSE = 2.19). This strategy improved the accuracy of prediction as compared with the existing prediction (CCC = 0.922 vs. 0.845). Still, over- or underestimations inherent to individual studies were evident and might be related to unaccountable factors, especially the quality of supplemental Mg sources. In conclusion, the vinegar test is a useful tool to rank inorganic Mg sources with alkaline properties. Including in vitro solubility data in Mg nutrition research could help to refine the prediction of bioavailable Mg contents and increase precision in feed formulation.

Co-occurrence of mycotoxins and other fungal metabolites in total mixed rations of cows from dairy farms in Punjab, Pakistan.

After India and the USA, Pakistan is the third country leading in global dairy production, a sector of very high socioeconomic relevance in Asia. Mycotoxins can affect animal health, reproduction and productivity. This study analysed a broad range of co-occurring mycotoxins and fungal secondary metabolites derived from Alternaria, Aspergillus, Fusarium, Penicillium and other fungal species. To complete this, a validated multi-metabolite liquid chromatography/electrospray ionization-tandem mass spectrometric (LC/ESI-MS/MS) method was employed, detecting 96 of > 500 tested secondary fungal metabolites. This first preliminary study demonstrated that total mixed rations (TMRs) (n = 30) from big commercial dairy cattle farms (> 200 lactating cows) in Punjab, Pakistan, presented ubiquitous contamination with mixtures of mycotoxins. The mean of mycotoxins per sample was 14, ranging from 11 to 20 mycotoxins among all TMR samples. Metabolites derived from other fungi and Fusarium spp. showed the highest levels, frequency and diversity among the detected fungal compounds. Among the most prevalent mycotoxins were Fusarium toxins like fumonisins B1 (FB1) (93%), B2 (FB2) (100%) and B3 (FB3) (77%) and others. Aflatoxin B1 (AFB1) was evidenced in 40% of the samples, and 7% exceeded the EU maximum limit for feeding dairy cattle (5 µg/kg at 88% dry matter). No other mycotoxin exceeds the EU guidance values (GVs). Additionally, we found that dietary ingredients like corn grain, soybean meal and canola meal were related to increased contamination of some mycotoxins (like FB1, FB2 and FB3) in TMR from the province of Punjab, Pakistan. Among typical forage sources, the content of maize silage was ubiquitous. Individually, the detected mycotoxins represented relatively low levels. However, under a realistic scenario, long-term exposure to multiple mycotoxins and other fungal secondary metabolites can exert unpredictable effects on animal health, reproduction and productivity. Except for ergot alkaloids (73%), all the groups of metabolites (i.e. derived from Alternaria spp., Aspergillus spp., Fusarium spp., Penicillium spp. and other fungi) occurred in 100% of the TMR samples. At individual levels, no other mycotoxins than AFB1 represented a considerable risk; however, the high levels of co-occurrence with several mycotoxins/metabolites suggest that long-term exposure should be considered because of their potential toxicological interactions (additive or synergistic effects).

Morphometric Measurements and Muscle Atrophy Scoring as a Tool to Predict Body Weight and Condition of Horses.

Accurate estimation of body weight (BW) and condition (BCS) is important in the equine practice. The main goal of this research was to develop models for the prediction of BW and BCS of horses in the practice using both common morphometric measurements and measurements of Cresty Neck Score (CNS) and Muscle Atrophy Scoring System (MASS) as a measure of muscularity. Our model showed that the BW of horses could be predicted with high reproducibility (concordance correlation coefficient = 0.97), accuracy (0.99), and precision (0.97) using the morphometric measurements of the height at withers, circumference of the chest, cane circumference, body length, and body circumference as well as the BCS, CNS, and muscle atrophy score of the hindlimbs. The stepwise multiple regression analysis revealed that the BCS of horses can be predicted with the data of parameters such as age, body length and an index consisting of measurements of the body circumference to height of withers, and the atrophy of the neck. Future research should use larger cohorts of animals to validate the findings of this study.

Sigla storax (Liquidambar orientalis) mitigates in vitro methane production without disturbances in rumen microbiota and nutrient fermentation in comparison to monensin.

AIM: The aim of this study was to investigate the in vitro dose-dependent effects of sigla storax (Styrax liquidus) on rumen microbiota and rumen microbial fermentation in comparison to monensin as a positive control. METHODS AND RESULTS: This study was carried out using a rumen simulation model (Rusitec). Treatments consisted of no additive (control), 10 mg l-1 of monensin sodium salt, 100 mg l-1 (Low-Sigla), and 500 mg l-1 (High-Sigla) of sigla storax (n = 6/treatment). In addition to rumen fermentation characteristics, rumen microbial composition was investigated using 16S rRNA sequencing. The methane variables and the acetate to propionate ratio decreased in the both High-Sigla and monensin groups (P < 0.05). High-Sigla had no effect on ammonia, total SCFA and nutrition degradation, while monensin decreased these parameters (P < 0.05). Unlike monensin, the sigla storax treatments did not affect the alpha or beta diversity indexes of the microbiota. The relative abundance of Methanomethylophilaceae and Ruminococcaceae decreased with High-Sigla and monensin (P < 0.05), and Atopobiaceae and Eggerthellaceae decreased with the both doses of sigla storax as well as monensin treatments (P < 0.05). Syntrophococcus, DNF00809, and Kandleria were among the genera that most decreased with High-Sigla and monensin (Q < 0.07) and were strongly positively correlated with methane production (r = 0.52-0.56). CONCLUSIONS: The high dose of sigla storax (500 mg l-1) decreased methane in the rumen ecosystem without adverse effects on nutrient degradation and SCFA production, and without dramatically impacting the microbial composition. Sigla storax might be a novel feed additive to mitigate methane in cattle.

Feeding concentrate with hay of different qualities modulates rumen histology, development of digestive tract as well as slaughter performance and meat quality of young dairy calves.

Concentrate-rich starter diets are commonly fed to dairy calves to stimulate growth performance. However, feeding high amounts of starter feed with low inclusion of forage fibre may jeopardise the development of the gastrointestinal tract (GIT). Moreover, studies investigating the effects of feeding on carcass and meat quality of young calves at rearing are rare. The objective of this research was to investigate the effect of hay quality and concentrate inclusion on the traits of GIT development, slaughter performance and veal quality of young dairy calves. The feeding trial covered the first 14 weeks of life. Seventeen male and three female Holstein calves (n = 20) were randomly allocated to four experimental groups, which received besides acidified whole milk different solid feeds: (1) 100% medium-quality hay (MQH), (2) 100% high-quality hay (HQH), (3) 30% medium-quality hay and 70% concentrate (MQH+C) and (4) 30% high-quality hay and 70% concentrate (HQH+C). The acidified whole milk was fed in the first 12 weeks of life, and calves had ad libitum access to solid feed and water from birth till slaughter. Calves were kept in individual boxes equipped with straw and slaughtered at the end of week 14. After slaughter, gut development traits, rumen histology, slaughter performance and meat quality were assessed. Overall, both concentrate inclusion and hay quality showed major effects on rumen histology and development of the GIT in dairy calves with minimal effects on most carcass cuts and meat quality traits. Concentrate-fed calves had significantly higher average daily gains, final body weights, blood amounts and proportions of organs from the circulatory and respiratory systems. Proportions of liver and kidneys were lowest in MQH-fed calves. The proportion of GIT was significantly lower in groups fed concentrates, but the weight of the reticulorumen was unaffected by solid feed. Concentrate feeding led to thicker keratin layer and epithelium as well as wider papillae in the rumen. Hay quality particularly affected the width of the papilla and epithelium thickness, while feeding hay without concentrate enhanced the thickness of submucosa and muscularis, as well as the size of parotid glands. In conclusion, the type of solid feed affects the development of the GIT with concentrate feeding holding the risk to induce keratinisation of rumen epithelium while enhancing performance and carcass traits.

Effects of High Concentrate-Induced Subacute Ruminal Acidosis Severity on Claw Health in First-Lactation Holstein Cows.

This study aimed to evaluate the effects of diet-induced subacute rumen acidosis (SARA) severity during transition and the early lactation period on claw health in 24 first-lactation Holstein heifers. All heifers were fed a 30% concentrate (in dry matter) close-up ration three weeks before calving, then switched to a high-concentrate ration (60% dry matter), which was fed until the 70th day in milk (DIM) to induce SARA. Thereafter, all cows were fed the same post-SARA ration with around 36% concentrate in dry matter. Hoof trimming was performed before calving (visit 1), at 70 (visit 2) and at 160 DIM (visit 3). All claw lesions were recorded, and a Cow Claw Score (CCS) was calculated for each cow. Locomotion scores (LCS 1-5) were assessed at two-week intervals. Intraruminal sensors for continuous pH measurements were used to determine SARA (pH below 5.8 for more than 330 min in 24 h). The cluster analysis grouped the cows retrospectively into light (≤11%; n = 9), moderate (>11-<30%; n = 7), and severe (>30%; n = 8) SARA groups, based on the percentage of days individual cows experienced SARA. Statistically significant differences were found between SARA groups light and severe in terms of lameness incidence (p = 0.023), but not for LCS and claw lesion prevalence. Further, the analysis of maximum likelihood estimates revealed that for each day experiencing SARA, the likelihood of becoming lame increased by 2.52% (p = 0.0257). A significant increase in white line lesion prevalence was observed between visits 2 and 3 in the severe SARA group. The mean CCS in severe SARA group cows were higher at each visit compared to cows in the other two groups, but without statistical significance. Overall, this is the first study indicating that first-lactation cows fed a similar high-concentrate diet but with a higher severity of SARA tended to have poorer claw health, albeit with only partial statistical evidence.

Changes in eating time, chewing activity and dust concentration in horses fed either alfalfa cubes or long-stem hay.

BACKGROUND: Chewing is an essential physiological process in horses; yet, the physical form of feeds may affect their chewing and feeding behaviour with consequences for equine digestion and health. OBJECTIVES AND METHODS: The present study evaluated the potential of a commercial forage cubes made from alfalfa and mixed meadow grasses to maintain chewing activity when compared with a traditional long and fibre-rich hay. An additional aim was to measure the dust formation during feeding. The experiment was a crossover design with six horses (11 ± 4 years old, mean ± SD), fed with 5 kg (as-fed basis) of their feed (long hay or alfalfa cubes) overnight. Eating and chewing activity was measured using the EquiWatch system with a sensor-based halter. RESULTS: Data showed that by feeding the same amount of feed overnight, cube feeding led to 24% shorter eating time (on average 67 min less) and 26% fewer total chews compared to the long hay. On an hourly basis, horses also spent more time eating and chewing the long hay compared to the cubes. The cube feeding led to a higher dust concentration of the inhalable fraction (<100 µm), but not of the thoracic (<10 µm) fraction. Nevertheless, average dust concentrations were generally low for both cubes and hay, whereby both were of sound hygienic status. CONCLUSION AND RECOMMENDATION: Our data suggest that feeding alfalfa-based cubes overnight generated shorter eating time and less chews than the long hay without major differences in the thoracic dust. Therefore, because of the decreased eating time and chews, alfalfa-based cubes should not be fed a sole forage source, especially when it is to be fed without restriction.

Zearalenone and Its Emerging Metabolites Promptly Affect the Rumen Microbiota in Holstein Cows Fed a Forage-Rich Diet.

The study investigated the short-term effects of a single oral bolus of zearalenone (ZEN) on the rumen microbiota and fermentation patterns in four rumen-cannulated Holstein cows fed a forage diet with daily 2 kg/cow concentrate. During the baseline day, cows received uncontaminated concentrate, followed by ZEN-contaminated concentrate on the second day, and again the uncontaminated concentrate on day three. Free rumen liquid (FRL) and particle-associated rumen liquid (PARL) were collected at different hours post-feeding on all days to analyze the prokaryotic community composition, absolute abundances of bacteria, archaea, protozoa, and anaerobic fungi, as well as short-chain fatty acid (SCFA) profiles. The ZEN reduced the microbial diversity in FRL but not in the PARL fraction. The abundance of protozoa was higher after ZEN exposure in PARL, which may be related to their strong biodegradation capacity that, therefore, promoted protozoal growth. In contrast, α-zearalenol might compromise anaerobic fungi as indicated by reduced abundances in FRL and fairly negative correlations in both fractions. Total SCFA significantly increased in both fractions after ZEN exposure, while the SCFA profile only changed marginally. Concluding, a single ZEN challenge caused changes in the rumen ecosystem soon after intake, including ruminal eukaryotes, that should be the subject of future studies.

Mixtures of Mycotoxins, Phytoestrogens, and Other Secondary Metabolites in Whole-Plant Corn Silages and Total Mixed Rations of Dairy Farms in Central and Northern Mexico.

Mycotoxins and endocrine disruptors such as phytoestrogens can affect cattle health, reproduction, and productivity. Most studies of mycotoxins in dairy feeds in Mexico and worldwide have been focused on a few (regulated) mycotoxins. In contrast, less known fungal toxins, phytoestrogens, and other metabolites have been neglected and underestimated. This study analyzed a broad spectrum (>800) of mycotoxins, phytoestrogens, and fungal, plant, and unspecific secondary metabolites in whole-plant corn silages (WPCSs) and total mixed rations (TMRs) collected from 19 Mexican dairy farms. A validated multi-metabolite liquid chromatography/electrospray ionization-tandem mass spectrometric (LC/ESI-MS/MS) method was used. Our results revealed 125 of >800 tested (potentially toxic) secondary metabolites. WPCSs/TMRs in Mexico presented ubiquitous contamination with mycotoxins, phytoestrogens, and other metabolites. The average number of mycotoxins per TMR was 24, ranging from 9 to 31. Fusarium-derived secondary metabolites showed the highest frequencies, concentrations, and diversity among the detected fungal compounds. The most frequently detected mycotoxins in TMRs were zearalenone (ZEN) (100%), fumonisin B1 (FB1) (84%), and deoxynivalenol (84%). Aflatoxin B1 (AFB1) and ochratoxin A (OTA), previously reported in Mexico, were not detected. All TMR samples tested positive for phytoestrogens. Among the investigated dietary ingredients, corn stover, sorghum silage, and concentrate proportions were the most correlated with levels of total mycotoxins, fumonisins (Fs), and ergot alkaloids, respectively.

Differential carbon utilization enables co-existence of recently speciated Campylobacteraceae in the cow rumen epithelial microbiome.

The activities of different microbes in the cow rumen have been shown to modulate the host's ability to utilize plant biomass, while the host-rumen interface has received little attention. As datasets collected worldwide have pointed to Campylobacteraceae as particularly abundant members of the rumen epithelial microbiome, we targeted this group in a subset of seven cows with meta- and isolate genome analysis. We show that the dominant Campylobacteraceae lineage has recently speciated into two populations that were structured by genome-wide selective sweeps followed by population-specific gene import and recombination. These processes led to differences in gene expression and enzyme domain composition that correspond to the ability to utilize acetate, the main carbon source for the host, at the cost of inhibition by propionate. This trade-off in competitive ability further manifests itself in differential dynamics of the two populations in vivo. By exploring population-level adaptations that otherwise remain cryptic in culture-independent analyses, our results highlight how recent evolutionary dynamics can shape key functional roles in the rumen microbiome.