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The aim of this study was to evaluate the effects of different anti-mycotoxin feed additives on the concentration of mycotoxins in milk, urine, and blood plasma of dairy cows fed diets artificially contaminated with mycotoxins. Secondarily, performance, total-tract apparent digestibility of nutrients, and blood parameters were evaluated. Twelve multiparous cows (165 ± 45 DIM, 557 ± 49 kg BW, and 32.1 ± 4.57 kg/d milk yield at the start of the experiment) were blocked according to parity, milk yield, and DIM and used in a 4 × 4 Latin square design experiment with 21-d periods, where the last 7 d were used for sampling and data analysis. Treatments were (1) mycotoxin group (MTX), basal diet (BD) without anti-mycotoxin feed additives; (2) hydrated sodium calcium aluminosilicate (HSCA), HSCA added to the BD at 25 g/cow per day; (3) mycotoxin deactivator (MD; Mycofix Plus, dsm-firmenich) added to the BD at 15 g/cow per day (MD15); and (4) MD added to the BD at 30 g/cow per day (MD30). Cows from all treatments were challenged with a blend of mycotoxins containing 404 μg of aflatoxin B 1 , 5,025 μg of deoxynivalenol (DON), 8,046 μg of fumonisins (FUM), 195 μg of T2 toxin (T2), and 2,034 μg of zearalenone (ZEN) added daily to the BD during the last 7 d of each period. Neither performance (milk yield and composition) nor nutrient digestibility was affected by treatments. All additives reduced aflatoxin M 1 (AFM1) concentration in milk, whereas MD15 and MD30 group had lower excretion of AFM1 in milk than HSCA. Deoxynivalenol, FUM, T2, or ZEN were not detected in milk of MD15 and MD30. Concentrations in milk of DON, FUM, T2, and ZEN were similar between MTX and HSCA. Except for AFM1, none of the analyzed mycotoxins were detected in urine of MD30 group. Comparing HSCA to MD treatments, the concentration of AFM1 was greater for HSCA, whereas MD30 was more efficient at reducing AFM1 in urine than MD15. Aflatoxin M1, DON, FUM, and ZEN were not detected in the plasma of cows fed MD30, and DON was also not detected in MD15 group. Plasma concentration of FUM was lower for MD15, similar plasma FUM concentration was reported for HSCA and MTX. Plasma concentration of ZEN was lower for MD15 than MTX and HSCA. Serum concentrations of haptoglobin and hepatic enzymes were not affected by treatments. Blood concentration of sodium was lower in HSCA compared with MD15 and MD30 groups. In conclusion, the mycotoxin deactivator proved to be effective in reducing the secretion of mycotoxins in milk, urine, and blood plasma, regardless of the dosage. This reduction was achieved without adverse effects on milk production or total-tract digestibility in cows fed multi-mycotoxin-contaminated diets over a short-term period. Greater reductions in mycotoxin secretion were observed with full dose of MD., (The Authors. Published by Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

Our objective was to determine the effects of feeding 25-hydroxyvitamin D 3 [25(OH)D 3 ], or vitamin D 3 (cholecalciferol) on plasma, mineral, and metabolite concentrations, mineral balance, mineral excretion, rumination, energy balance, and milk production of dairy cows. We hypothesized that supplementing 3 mg/d of 25(OH)D 3 during the prepartum period would be more effective than supplementing vitamin D 3 at the National Research Council (2001) levels to minimize calcium imbalance during the transition period and improve milk production of dairy cows. Forty multiparous, pregnant nonlactating-Holstein cows were enrolled in this study. Body weight, body condition score, parity, and milk yield in the previous lactation (mean ± standard deviation) were 661 ± 59.2, 3.46 ± 0.35, 1.79 ± 0.87, and 33.2 ± 6.43 kg/d, respectively. Cows were enrolled into the blocks (n = 20 for each treatment) at 30 d of the expected day of calving to receive an acidogenic diet (373 g/kg of neutral detergent fiber and 136 g/kg of crude protein, dry matter basis; -110 mEq/kg) associated with the treatments: (1) control (CTRL), vitamin D 3 at 0.625 mg/d (equivalent to 25,000 IU of vitamin D 3 /d) or (2) 25(OH)D 3 at 3 mg/d (equivalent to 120,000 IU of vitamin D 3 /d). All cows were fed with the base ration for 49 d after calving. Blood samples were taken on d 7, 0, 1, 2, 21, and 42, relative to calving. No effect of treatment was observed for prepartum dry matter intake or body condition score. A trend for increase of ionized Ca was observed for the cows fed 25(OH)D 3 , compared with the CTRL, but no effect of treatment was detected for total Ca or total P. Feeding 25(OH)D 3 increased colostrum yield. The plasmatic concentration of 25-hydroxyvitamin D 3 was increased with 25(OH)D 3 supplementation. 25-Hydroxyvitamin D 3 supplementation increased plasma glucose concentration at parturition. The postpartum dry matter intake was not influenced by treatments. Feeding 25(OH)D 3 increases milk yield, 3.5% fat-corrected milk, and energy-corrected milk and improves milk yield components in early lactation. Overall, these findings suggest that 25(OH)D 3 at 3 mg/d can improve the energy metabolism and lactation performance, compared with the current-feeding practice of supplementing vitamin D 3 at 0.625 mg/d., (The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

The objective of this study was to evaluate the effects of exogenous enzymes on nutrient intake and digestibility, rumen fermentation, and productivity of mid-lactating cows. Experiment 1 was designed to test increasing doses [0, 0.5, 1.0, or 1.5 g/kg of dry matter (DM)] of a combination of 2 enzyme products with xylanase and β-glucanase activities (Ronozyme Wx and Ronozyme VP, respectively; DSM Nutritional Products) on rumen fermentation and total apparent digestibility. Enzyme combinations had a ratio of endo-1,3(4)-β-glucanase to endo-1,4-β-xylanase of 8:2 (wt/wt). For experiment 1, 8 rumen cannulated lactating cows were used into a double 4 × 4 Latin square design experiment with 14 d of diet adaptation and 7 d of sampling. Despite no differences in feed intake, carbohydrases linearly increased neutral detergent fiber digestibility. Treatments marginally affected rumen fermentation, where a linear trend for lower rumen pH and a linear trend for greater isobutyrate concentration were observed with increasing enzyme dose. A trend for lower rumen NH 3 -N concentration was observed for cows receiving carbohydrases in comparison with control group. When comparing all enzyme treatments against control group, cows fed enzymes tended to produce more 3.5% fat-corrected milk (FCM), produced more milk fat, and had greater blood glucose concentration. Experiment 2 evaluated 3 doses (0, 0.5, or 0.75 g/kg of DM) of the same combination of enzyme products on performance of cows (n = 36) in a complete randomized block (n = 12) design. Cows received treatments for 9 wk. No interaction effects between treatments and time were observed for all variables assessed in this study. In agreement with experiment 1, no differences were detected for feed intake, but cows fed the enzyme products tended to produce more 3.5% FCM and milk fat compared with control. In addition, cows fed enzymes exhibited greater efficiency of FCM production (FCM ÷ DM intake) compared with control. No differences were detected for intake and productivity when comparing the 2 doses of carbohydrases. In summary, the enzyme products tested in this study may improve feed efficiency due to greater milk fat concentration., (Copyright © 2021 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Two experiments were carried out to evaluate a blend of essential oils (EO) combined with amylase as an alternative to ionophores and its potential for reducing the use of antibiotics in the dairy industry. In experiment 1, 8 rumen-cannulated Holstein cows (576 ± 100 kg of body weight, 146 ± 35 d in milk, and 35.1 ± 4.0 kg/d of milk yield at the start of the experiment) were assigned to a 4 × 4 Latin square experiment with 21-d periods to determine the influence of feed additives on total apparent digestibility of nutrients, ruminal fermentation, N utilization, microbial protein synthesis, blood glucose and urea concentrations, and milk yield and composition in dairy cows. Treatment sequences assigned to cows in each block included no feed additives (control; CON); monensin (MON) added at 13 mg/kg of diet dry matter (DM); a blend of EO supplemented at 44 mg/kg of diet DM; and EO treatment combined with α-amylase at 330 kilo novo units/kg of diet DM (EOA). Differences among treatments were studied using orthogonal contrasts as follows: CON versus feed additives (MON, EO, and EOA), MON versus EO and EOA, and EO versus EOA. No differences were detected in nutrient intake and digestibility in cows. In general, feed additives decreased ruminal NH 3 -N concentration of cows, notably when diet was supplemented with MON. Furthermore, feed additives increased ruminal concentrations of acetate, butyrate, and branched-chain fatty acids. Cows fed treatments containing EO and EOA exhibited lower pH, higher NH 3 -N, and a trend to greater total volatile fatty acid concentration in the ruminal fluid compared with cows fed MON. Treatments containing EO increased ruminal butyrate concentration compared with MON. No treatment × time interaction effect was observed on ruminal fermentation measurements. Cows fed diets supplemented with feed additives had greater efficiency of N transfer into milk (milk N:N intake), whereas cows fed EOA exhibited greater N transfer into milk than those fed EO. Treatments had no effect on milk yield and composition, but feed additives increased the milk yield efficiency (milk yield divided by dry matter intake), whereas treatments containing EO had similar milk yield efficiency compared with MON. For experiment 2, 30 multiparous Holstein cows (574 ± 68 kg of body weight, 152 ± 54 d in milk, and 30.9 ± 4.1 kg/d of milk yield at the start of the experiment) were enrolled to a randomized complete block design experiment. The MON, EO, and EOA treatments were randomly assigned to cows within blocks (n = 10), and feed additives were provided throughout a 9-wk period. No differences were found in nutrient intake and digestibility, but cows fed EOA tended to exhibit greater dry matter intake than those fed EO. Blood metabolites and milk production were not affected by treatments. However, cows fed MON or EOA had greater milk protein content than those cows fed treatments containing EO. Feeding EO with or without amylase had similar response to feeding MON in terms of feed intake and milk yield, with a small negative effect on milk protein yield when feeding EO alone. Feed additives increased the concentrations of acetate, butyrate, and branched-fatty acids in ruminal fluid, whereas treatments containing EO had greater ruminal butyrate and NH 3 -N concentrations. Therefore, either EO or EOA can replace MON in diets of dairy cows while maintaining performance., (Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Exogenous amylase supplementation can increase starch and fiber digestibility in lactating dairy cows. We evaluated the effect of exogenous amylase supplementation on diets with high starch concentration (32% of dry matter). Twenty-eight Holstein cows (171 ± 80 d in milk, 4 primiparous) received a standard diet for 14 d and then a treatment for 63 d, in a covariate-adjusted randomized block design with repeated measures over time. Treatments were amylase [0.5 g of Ronozyme RumiStar (DSM Nutritional Products, Basel, Switzerland) per kg of total mixed ration dry matter] or control. The diets contained (% of dry matter): 39.4% corn silage, 11.2% rehydrated and ensiled mature corn grain, and 11.7% finely ground mature corn. Amylase increased milk yield (32.3 vs. 33.0 kg/d) and reduced dry matter intake (20.7 vs. 19.7 kg/d), increasing feed efficiency (1.52 vs. 1.63). Amylase also increased milk lactose synthesis (1.49 vs. 1.56 kg/d) and plasma glucose concentration (59.3 vs. 68.6 mg/dL). Secretions of milk fat and protein did not differ. Although milk urea N did not differ, amylase reduced the concentration of urea N in blood, suggesting an increase in ruminal starch degradation. However, the total-tract apparent digestibility of starch (96.3% of intake) and neutral detergent fiber (44.4% of intake), ruminal fermentation profile, and microbial yield estimated by urinary allantoin excretion did not differ. Cows fed amylase sorted in favor of long feed particles and against short particles, had shorter chewing activity (780 vs. 699 min/d), and had fewer meals per day (11.5 vs. 9.7). Amylase improved the feed efficiency of lactating cows fed a high-starch diet; the enzyme increased milk yield and reduced intake., (Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

The objective of this study was to compare ceftiofur hydrochloride with a positive control protocol for intramammary treatment of nonsevere clinical mastitis in dairy cows. A total of 264 clinical mastitis cases on 11 commercial dairy farms were treated with intramammary infusions, once a day for 4 d using 1 of 2 treatments: (1) ceftiofur hydrochloride 125mg; or (2) control: tetracycline 200mg + neomycin 250mg + bacitracin 28mg + prednisolone 10mg. Streptococcus agalactiae was the most frequently isolated gram-positive pathogen from clinical mastitis, followed by Staphylococcus aureus. Klebsiella spp. and Escherichia coli were the most isolated gram-negative bacteria from clinical mastitis. No significant differences were observed between treatments regarding the overall clinical cure, bacteriological cure, and new infection. No effect of treatment regimen was observed when the bacterial group (gram-positive vs. gram-negative) was evaluated. The overall clinical cure was 0.79 for ceftiofur-treated cows and 0.74 for control-treated cows, whereas the overall bacteriological cure was 0.79 for ceftiofur-treated cows and 0.76 for control-treated cows. Furthermore, the new intramammary infection was 0.10 for cows treated with ceftiofur and 0.11 for cows treated with control. In conclusion, the use of intramammary ceftiofur hydrochloride for treatment of nonsevere clinical mastitis has similar efficacy as a treatment regimen with a combination of antimicrobial agents (tetracycline + neomycin + bacitracin)., (Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

The aim of this study was to develop and evaluate a real-time quantitative PCR (qPCR)-based method to detect and quantify Staphylococcus aureus in bronopol-preserved milk samples from subclinical intramammary infections (IMI). Serial dilutions of milk artificially inoculated with Staph. aureus ATCC 29213 were used to establish a standard curve (cfu/mL) of the qPCR assay targeting the Staph. aureus thermonuclease-encoding gene nuc according to the strain plate count. The analytical sensitivity, specificity, and repeatability of the qPCR assay were determined. A total of 60 milk samples, collected from mammary quarters without abnormal appearance and with positive isolation of Staph. aureus, were submitted to both the qPCR protocol and Staph. aureus plate counting and results from both methods were compared. Staphylococcus aureus from bronopol-preserved, subclinical IMI milk samples were not accurately enumerated by qPCR compared with plate counting of the nonpreserved, raw milk sample. The detection limit of the qPCR protocol of inoculated Staph. aureus ATCC 29213 in bronopol-preserved milk samples was 1.04 × 10(1) cfu/mL. The qPCR protocol can be a high-throughput and rapid diagnostic assay to accurately detect Staph. aureus IMI from bronopol-preserved milk samples compared with a traditional culturing method. However, the proposed qPCR protocol is not accurate for counting of Staph. aureus in bronopol-preserved milk samples from naturally infected mammary glands., (Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)