Search Results (268)

Winery wastewater (WWW), if released untreated, poses a serious environmental threat due to its high organic load. In this study, Chlorella vulgaris was cultivated in diluted WWW to assess its suitability as a culture medium. Two outdoor cultivation systems—a 270 L raceway and a 40 L bubble column—were operated over 33 days using synthetic medium (control) and WWW. A flow cytometry (FC) protocol was implemented to monitor key physiological parameters in near-real time, including cell concentration, membrane integrity, chlorophyll content, cell size, and internal complexity. At the end of cultivation, the bubble column yielded the highest cell concentrations: 2.85 × 10⁶ cells/mL (control) and 2.30 × 10⁶ cells/mL (WWW), though with lower proportions of intact cells (25% and 31%, respectively). Raceway cultures showed lower cell concentrations: 1.64 × 10⁶ (control) and 1.54 × 10⁶ cells/mL (WWW), but higher membrane integrity (76% and 36% for control and WWW cultures, respectively). On average, cells grown in the bubble column had a 22% larger radius than those in the raceway, favouring sedimentation. Heterotrophic cells were more abundant in WWW cultures, due to the presence of organic carbon, indicating its potential for use as animal feed. This study demonstrates that FC is a powerful, real-time tool for monitoring microalgae physiology and optimising cultivation in complex effluents like WWW. Full article

Concentration polarization (CP) is one of the inherent problems that lowers the operating performance of forward osmosis (FO) membranes. Therefore, a quantitative evaluation of CP is vital to understand its impact on the FO process. This study systematically investigated the influences of different CPs on the osmotic pressure drop across the membrane under different conditions by using the water transmission coefficient, η_WT, defined as the ratio of the measured water flux to the theoretical water flux. The results showed that η_WT decreased with an increase in the concentration gradient between the draw solution (DS) and the feed solution (FS) under different conditions. The proportions of osmotic pressure drop caused by dilutive internal concentration polarization (ICP) increased, while those caused by concentrative external concentration polarization (ECP) decreased, in different types of DSs in FO mode. Both ECP and ICP were found to be capable of reducing osmotic pressure. However, the internal CP had the dominant influence. To better understand the adverse effects of CP, using an organic FS provided greater insight than using deionized (DI) water as the FS. As the FS concentration increased, the water flux reduced, and the adverse effects of CP worsened. CaCl₂ led to a greater reduction in water transfer efficiency than NaCl when used as the DS. In comparison to FO mode, pressure-retarded osmosis (PRO) mode led to greater pure water flux and flux decline. In FO mode, both the proportion of dilutive ICP and the η_WT decreased, while the proportion of concentrative ECP increased over time. However, in PRO mode, the proportions of dilutive ECP and concentrative ICP increased, and η_WT gradually decreased. Dilutive ICP had a significant negative effect on osmotic pressure in the former, while dilutive ECP was dominant in the latter. Full article

This study evaluated the effects of supplementing early-lactation Holstein cows with rumen-protected omega-3 fatty acids (calcium salts) on productive and reproductive performance. Thirty-six multiparous cows were randomly assigned to one of two treatments from 21 ± 2 days before calving to 105 ± 5 days in milk (DIM): a Control group (C) or an Omega-3-supplemented group (O-3), receiving a blend of linseed and fish oil (60:40). Both groups were fed isoenergetic diets, with ground corn as the control supplement. Total dry matter and net energy intake did not differ between treatments. A treatment-by-time interaction was observed for milk yield, with cows in the O-3 group producing more milk than controls at specific time points. Additionally, O-3 cows had higher overall protein yield and improved feed efficiency. No differences were found in body weight, BCS, glucose, insulin, IGF-1, or urea concentrations, but a tendency toward higher plasma NEFA and BHBA concentrations and lower energy balance was observed in the O-3 group. Supplementation increased plasma cholesterol and progesterone concentrations and was associated with a higher proportion of cows being pregnant at 130 DIM. These findings suggest that omega-3 supplementation may improve specific aspects of lactational performance and reproductive efficiency without compromising metabolic status. Full article

This study aimed to evaluate the microbiological quality of colostrum on three dairy farms with different colostrum management hygiene practices and to compare it with the current colostrum quality guidelines. On farm A, colostrum was fed raw, while on farms B and C it was heat treated. On farms A and B, the feeding equipment was cleaned manually, while on farm C, an automated cleaning system was used. Samples were collected from the calf-feeding equipment and submitted for microbial culture: total plate count (TPC); total coliform count (TCC); and E. coli, enterobacteria (ENTB), staphylococci (STAP), and lactic acid bacteria counts. In addition, pH, water activity (a_W), and Brix were analyzed. Colostrum quality was defined as follows: good quality (GQ)—TPC < 100,000, TCC < 10,000, STAP < 50,000 cfu/mL, and Brix ≥ 22%; excellent quality (EQ)—TPC < 20,000, TCC < 100, STAP < 5000 cfu/mL, and Brix ≥ 25%. Mean concentrations were as follows: TPC was 3.99 × 10⁵ cfu/mL (min: 40.00, max: 1.32 × 10⁷ cfu/mL); TCC was 1.17 × 10⁴ cfu/mL (min: <detection limit, max: 6.37 × 10⁵ cfu/mL); and STAP was 1.77 × 10⁴ cfu/mL (min: <detection limit, max: 3.50 × 10⁵ cfu/mL). Approximately 54% (GQ) and 32% (EQ) of samples met the defined criteria. Farm C consistently showed lower microbial counts across all culture types. Colostrum from farm B had lower TCC, LAB, and E. coli counts than farm A but not TPC, STAP, and ENTB. These results showed that a considerable proportion of calves were fed colostrum with suboptimal quality, especially when less rigorous hygiene practices were implemented. Full article

This study examined total ammoniacal nitrogen (TAN) rejection by two reverse osmosis (RO) and two nanofiltration (NF) membranes as a function of pH for three ammonium salts to optimize conditions for a hybrid membrane system that can produce high-purity TAN streams suitable for reuse. The results showed that TAN rejection was significantly influenced by membrane type, feed pH, and the ammonium salt used. This study represents the first attempt to simulate real manure wastewater conditions typically found in pig manure. TAN rejection for (NH₄)₂SO₄ and NH₄HCO₃ reached up to 95% at pH values below 7, with the SW30 membrane showing the highest performance (99.5%), attributed to effective size exclusion and electrostatic repulsion of SO₄²⁻ and HCO₃⁻ ions. In contrast, lower rejection was observed for NH₄Cl, particularly with the MPF-34 membrane, due to its higher molecular weight cut-off (MWCO), which diminishes both exclusion mechanisms. TAN rejection decreased markedly with increasing pH across the BW30, NF90, and MPF-34 membranes as the proportion of uncharged NH₃ increased. The lowest rejection rates (<15%) were recorded at pH 11.5 for both NF membranes. These results reveal a notable shift in separation behavior, where NH₃ permeation under alkaline conditions becomes dominant over the commonly reported NH₄⁺ retention at low pH. This novel insight offers a new perspective for optimizing membrane-based ammonia recovery in systems simulating realistic manure wastewater conditions. TAN recovery was evaluated using a hybrid membrane system, where NF membranes operated at high pH promoted NH₃ permeation, and the SW30 membrane at pH 6.5 enabled TAN rejection as (NH₄)₂SO₄. This hybrid system insight offers a new perspective for optimizing membrane-based ammonia recovery in systems simulating realistic manure wastewater conditions. Based on NH₃ permeation and membrane characteristics, the NF90 membrane was operated at pH 9.5, achieving a TAN recovery of 48.3%, with a TAN concentration of 11.7 g/L, corresponding to 0.9% nitrogen. In contrast, the MPF-34 membrane was operated at pH 11.5. The NF90–SW30 system also achieved a TAN recovery of 48.3%, yielding 11.7 g/L of TAN with a nitrogen content of 1.22%. These nitrogen concentrations indicate that both retentate streams are suitable for use as liquid fertilizers in the form of (NH₄)₂SO₄. A preliminary economic assessment estimated the chemical consumption cost at 0.586 EUR/kg and 0.729 EUR/kg of (NH₄)₂SO₄ produced for the NF90–SW30 and MPF-34–SW30 systems, respectively. Full article

Essential fatty acids are extremely important nutrients in the diet of fish, and the balance between arachidonic acid (ARA) and eicosapentaenoic acid (EPA) is crucial for the healthy growth of fish. Six isonitrogenous and isolipidic basal diets were given to 540 juvenile fat greenling (Hexagrammos otakii) (31.4 ± 1.5 g) for 8 weeks to investigate the effects of dietary ARA/EPA ratio on growth performance, antioxidant capacity and lipid metabolism-related genes of juvenile H. otakii. The control group (A) had 7% fish oil added as the main fat source, while the experimental groups had 4% fish oil as the basic fat source, with varying proportions of ARA and EPA concentrates added to formulate five diets with varying ARA/EPA ratios (B 2.66; C 1.34; D 1.01; E 0.47; F 0.19). The experimental results revealed that adding ARA and EPA to the diet increased the percent weight gain (PWG) and feed conversion ratio (FCR) of juvenile H. otakii, and the PWG and FCR were greatest under Group E dietary conditions. The specific activities (U/mg protein) of superoxide dismutase (SOD), catalase (CAT), and total antioxidant capacity (T-AOC) in the liver, as well as serum SOD and CAT were significantly higher in Groups D and E than those in other groups (p < 0.05). Malondialdehyde (MDA, nmol/g protein) content in the liver and serum was significantly lower in Group E than that in other groups (p < 0.05). Moreover, groups D and E exhibited significant increases in the specific activities (U/mg protein) of intestinal trypsin, lipase, and amylase, as well as in the intestinal villus length (p < 0.05). The incorporation of ARA and EPA into the feed reduced the expression levels of fat synthesis genes such as fas, scd1, accα, and srebp1, as well as the expression of lipolysis genes atgl and hsl. However, it also increased the expression of the lipolytic genes cpt1 and ppara. The ARA/EPA ratios in the dietary were 0.47 and 1.01, respectively, which are appropriate for enhancing growth efficiency, antioxidant enzyme activity, intestinal digestive enzyme activity and lipid metabolism regulation. Full article

Alfalfa (Medicago sativa L.) saponins (AS), primarily pentacyclic triterpenoids, may reduce methane emissions from goats (Capra hircus L.). This study evaluated the methane-suppressing potential of Aspergillus niger β-glucosidase-modified AS using in vitro rumen fermentation (0.10 mg/mL inoculum, 24 h incubation, gas chromatography detection). Among the 21 alfalfa cultivars, Pegasis (fall dormancy 9) exhibited the highest antioxidant efficacy (half maximum effective concentration 2.13 mg/mL) and the lowest ferric-reducing activity (0.32 μM Fe²⁺/g) (p < 0.05). Fresh/silage AS reduced methane proportions to 4.50–5.21% of total gas, while enzymatic biotransformation further decreased it to 3.34–3.48% (p < 0.05). Methanogen abundance declined by 20.10–44.93%, and general anaerobic fungi declined by 34.22–44.66% compared to untreated AS (p < 0.05). Metabolomics linked methane suppression to six pathways, including zeatin biosynthesis (via nucleotide metabolites accumulation) and prolactin signaling pathway (via bioactive molecules downregulation), suggesting impaired methanogen energy metabolism and hydrogen flux redirection as mechanisms. Enzymatic AS also enhanced volatile fatty acid production, indicating improved fiber digestion. These in vitro findings demonstrate that enzyme-treated AS modulates rumen fermentation through dual methane mitigation and nutrient utilization enhancement, offering a sustainable feed additive strategy for livestock. Full article

Brassica-derived feeds have been recognized for their economic and environmental benefits in ruminant nutrition. However, their utilization is constrained by the presence of glucosinolates and sulfur-containing compounds that exhibit both beneficial and adverse effects. This meta-analysis included 36 studies that evaluated the impact of glucosinolate intake on ruminant performance, nutrient digestibility, milk composition, and methane emissions. This analysis, conducted in accordance with PRISMA guidelines, revealed that glucosinolate supplementation resulted in a quadratic increase in milk urea nitrogen concentration (p = 0.017). Additionally, significant interactions between glucosinolate level and source influenced crude protein digestibility (p = 0.026). Milk composition parameters, including 4% fat-corrected milk, energy-corrected milk, milk protein, and lactose proportions, were significantly affected (p < 0.05). Furthermore, methane emissions (g/kg DMI) decreased quadratically with increasing glucosinolate intake (p = 0.003), with additional interactions observed between dietary treatments and animal species (p = 0.029). Propionate and isobutyrate concentrations increased in a quadratic and linear manner, respectively (p < 0.05). These findings suggest that glucosinolate-containing feed can enhance nutrient utilization and mitigate methane emissions in ruminants. However, the magnitude of these effects is dependent on the glucosinolate dosage, source, animal species, and dietary composition, necessitating further research to optimize their use in ruminant nutrition. Full article

Nanoemulsified corn oil was tested on twenty-one multiparous lactating Barki ewes (mean ± SD: 3 ± 0.4 parity, 44.3 ± 1.9 kg body weight, 30 ± 2.7 months of age, and 402 ± 23 g/d of prior milk production) randomly allocated to the following treatments (n = 7 ewes/group): Control—a basal diet consisting of 50% concentrate mixtures and 50% berseem clover; CO—the Control diet + 3% of corn oil; NCO—the Control diet + 3% of nanoemulsified corn oil. A completely randomized design of 25 days of adaptation and 5 days of sampling was employed with seven ewes per treatment. Despite feeding oil according to the recommended values, CO decreased the dry matter intake by 8.3% and 6.7% compared to the Control and NCO, respectively. The negative impact of CO extended to reducing the concentrations of ammonia and total volatile fatty acids in the rumen. On the other hand, NCO had less effect on the biohydrogenation intermediates profile compared to CO; noticeably, higher proportions of unsaturated fatty acid (UFA) were associated with NCO; these results were also supported by an increase in the rumen microbial population with NCO compared to CO, especially the biohydrogenation bacteria, which showed higher abundance with NCO despite the low presence of biohydrogenation intermediates. In conclusion, the NCO demonstrated the ability to decrease the transformation of unsaturated fatty acids into saturated fatty acids in the biohydrogenation environment. This effect was not associated with decreased dry matter intake, changes in nutrient digestibility, or alterations in fermentation patterns. Full article

Feed is the single greatest cost for cattle producers. Improvements to feed efficiency, or how animals convert feed to body weight gain, will ultimately improve producer profits. The objective of this study was to determine whether the expression of genes in the transcriptome of whole blood from heifers (n = 61) on a forage ration was related to the quantitative phenotypes for average daily gain (ADG), average daily feed intake (ADFI), and gain-to-feed (G:F). Total RNA was isolated from whole blood collected mid-study on day 42 on feed and was used for hematologic analysis and RNA-sequencing. Lymphocyte (LYM) count was negatively associated with ADG, and mean corpuscular hemoglobin concentration (MCHC) was positively associated (p < 0.05). Red blood cell (RBC) count was negatively associated with ADFI. While MCHC was positively associated with G:F, white blood cell (WBC), LYM, and basophil (BAS) counts were negatively associated with G:F (p ≤ 0.05). The model used to identify differentially expressed genes (DEG) for ADFI, ADG, and G:F included sire, breed, pen, age, and proportions of blood cell types. No genes were differentially expressed for ADFI. Three genes were identified as differentially expressed for ADG, and 17 were identified for G:F. Three of the differentially expressed genes for G:F and ADG (PLOD1, FAH, and COL1A2) had been previously associated with feed efficiency in livestock and may be useful for further validation in other populations of cattle. The negative associations between WBC and LYM and ADG and G:F may be expected since the production of WBC is an energetic process that may reduce body weight gain and efficiency. The associations between RBC hematological parameters suggest that there may be benefit for animals with higher levels of hemoglobin per RBC by improving oxygen-carrying capacity. Full article

This study investigated the feasibility of incorporating Chenopodium album L. (CAL) into ruminant feed ingredients through evaluating the effects of harvest time and substitution levels on in vitro rumen fermentation. In the first phase, a sole-substrate experiment was conducted using CAL harvested from June to August, analyzing its chemical composition and total saponins content. The impact of harvest time on fermentation parameters was assessed with CAL as the sole substrate. The second phase involved a mixed-substrate experiment using an early-fattening Hanwoo diet (30% rice straw and 70% concentrate), where increasing proportions of CAL (control: 0%, T1: 5%, T2: 10%, T3: 15%, and T4: 20%) replaced rice straw. Seasonal variations in CAL composition influenced the fermentation characteristics. CAL harvested in July exhibited higher fermentability, with total volatile fatty acids (TVFAs) reaching 103.87 mM at 72 h. In contrast, CAL harvested in August showed lower fermentability and digestibility. However, August-harvested CAL was selected for the subsequent experiment, as it provided a more practical balance of sufficient biomass yield and a higher saponins concentration, aligned with the study’s methane mitigation objectives, while also exhibiting a fiber composition comparable to that of rice straw. We hypothesized that the saponins in CAL contribute to methane reductions. Supplementation with 15% of CAL significantly reduced methane production per gram of inoculated and digested dry matter (p < 0.05), likely due to differences in crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and saponins content. However, despite having the lowest fiber content, T4 (20% CAL) exhibited the lowest in vitro dry matter digestibility (IVDMD), suggesting that factors such as saponins, CAL’s chemical composition, or microbial shifts may have hindered digestibility. Ammonia–nitrogen production increased from 0 to 3 h, but it continuously decreased between 3 and 9 h due to microbial growth and nitrogen assimilation, as microbes incorporate ammonia into their biomass (p < 0.05). Fermentation characteristics further revealed that the acetate-to-propionate (A/P) ratio decreased with increasing CAL levels, with T4 showing the lowest ratio (1.55 at 72 h), confirming a shift toward propionate-based fermentation. Notably, T2 (10% CAL) showed an optimized fermentation efficiency, producing the highest TVFA concentration at 24 h (98.28 mM). These findings highlight the potential for using CAL as a functional feed ingredient, with moderate substitution levels (10–15%) enhancing fermentation efficiency while reducing methane production. Full article

The use of cassava as a feed resource is the main focus of strategies that aim to increase the efficiency of beef cattle. In this study, the ratio of fresh cassava tops to roots (CTR) was 1:1, 1:2, 1:3, and 1:4 w/w, in addition to the incorporation of yeast and lactic acid bacteria (YL). CTRS was inoculated in vitro with rumen fluid and a substrate mixture to evaluate the gas production and fermentation quality. In vivo, crossbred beef cattle were randomly allocated to three dietary treatments: a control group and two groups that received total mixed ration (TMR) silage with either 35% or 70% of the concentrate replaced with CTRS. This study found that the levels of crude protein and condensed tannins (CTs) in CTRS were relatively increased by the addition of cassava tops (p < 0.05), while the fermentation pH decreased as the proportion of cassava roots increased. CTRS significantly enhanced in vitro dry matter digestibility, cumulative gas at 96 h, gas production kinetics, and MBP (p < 0.05), especially in the 1:2 group. In the in vivo experiment, CTRS increased DM intake, CP, and propionic acid concentration compared to the control group and showed great potential for improving NDF digestibility. Moreover, when the concentrate in the TMR silage was substituted with CTRS and offered to crossbred beef cattle, it increased ruminal NH₃-N and blood glucose levels (p < 0.05). The TMR silage substituted with 70% CTRS reduced the feed cost by 50.54% (p < 0.05). Our study findings suggest that optimizing the inclusion of CTRS in TMR silage could be a viable strategy for beef producers aiming to enhance cattle performance and profitability. Full article

There is growing interest in adding marine algae to poultry feed rations. The aim of the present study is to examine the effect of various inclusions of Sargassum sp., Gracilaria sp., and Spirulina sp. on productive performance, serum proteins, liver proteins, meat quality, and antioxidant activity in broiler chickens. There were seven dietary treatments (TRTs) as follows: TRT 1 was the control group without algae; TRT 2 was enriched with Sargassum sp. at 1% of the diet; TRT 3 with Sargassum sp. at 2% of the diet; TRT 4 with Gracilaria sp. at 0.5% of the diet; TRT 5 with Gracilaria sp. at 1% of the diet; TRT 6 with Spirulina sp. at 5% of the diet; TRT 7 with Spirulina sp. at 7.5% of the diet. Each treatment was replicated ten times, with 17 birds per replicate, and the analyses were performed in triplicates. Results of the feed rations proximate analyses revealed that the formulated diets contained the required amounts of protein, fat, fiber, ash, and moisture, to be fed to the broiler chickens. There was no effect of marine algae on the production performance parameters of the birds. All the enriched birds performed normally as the control group. It was shown that enriching the broiler diet with 1% Sargassum sp. Induced an increase in the total serum proteins, while Gracilaria sp. algal inclusion reduced the total serum proteins, compared to the control group. At five weeks of age, enriching broiler diets with 5% Spirulina sp. resulted in a higher concentration of total serum protein-C than the control group and the group enriched with 7.5% inclusion. Enriching the diet of 3- wks old broilers with Sargassum sp. at 2% elevated the proportions of serum LFABP. The maximum proportion of omega 6 fatty acid (∑n-6) was observed in the group of birds that received the control diet, while the proportion of omega 3 fatty acid (∑n-3) was highest in the algae-enriched groups. The results showed that all algal inclusions lowered the ratio of omega-6 to omega-3 fatty acids (∑n-6:∑n-3). Enriching broiler chickens with Spirulina at 5% and 7.5% increased the HDL concentration, compared to the control group. The palatability of meat for color, texture, flavor, appearance, smell, and overall acceptability was not negatively affected by algal inclusions. All algal inclusions enhanced the anti-oxidative status of broilers and lipid oxidative stability of the stored feed rations. In general, it can be concluded that marine algal inclusions showed no effect on the productive performance of the broiler chickens and can be used without any detrimental effects in poultry feed rations. Full article

The purpose of this study was to investigate the effects of the optimization of dietary energy supply on the growth performance, nutrient digestibility, energy metabolism, nutrient oxidation, slaughter performance, and meat quality of growing and fattening pigs under a low-temperature environment. In this study, forty-eight 60-day-old growing barrows (Duroc × Landrace × Large White) with an initial body weight of 31.24 ± 3.56 kg were completely randomized into two treatment groups, with four replicates in each treatment group and six pigs in each replicate. The two groups were fed diets with equal protein levels and different energy levels (a conventional diet and an energy-optimized diet); the dietary energy level was increased by 8% by adding 6% fat, and the two groups were kept at the same ambient temperature (10 ± 1 °C) all day. After 5 d of prefeeding, the final weight reached approximately 110.00 kg prior to slaughter (99 days of age), and four pigs with a body weight of about 80.00 kg were selected in the two groups for digestion, metabolism, and respiratory calorimetry. The results showed that the average daily feed intake of the TES group (energy-optimized diet group, high fat and energy) was lower than that of the CON group (conventional diet group, normal fat and energy) (p < 0.05). Compared with the CON group, the feed-to-gain ratio was lower in the TES group during the fattening period (60–110 kg) (p < 0.05). Compared to the CON group, fat and energy digestibility in the TES group were higher (p < 0.05), fecal nitrogen and urine nitrogen were lower (p < 0.05), the nitrogen deposition rate increased (p < 0.05), and fat oxidation and the sedimentation energy rate also increased (p < 0.05). The serum triglyceride concentration in the TES group was higher than that in the CON group (p < 0.05). Compared to the CON group, the carcass weight, body fat content, backfat thickness, and eye muscle area in the TES group increased (p < 0.05); the L* value of flesh color also increased (p < 0.05); and the shear force was lower (p < 0.05). The dietary energy should be optimized under a low-temperature environment, and the feed conversion efficiency of fattening pigs could be improved by improving dietary energy levels by adding fat, increasing the fat oxidation proportion, promoting nitrogen deposition and sedimentation energy, and improving slaughter performance and meat quality. Full article

Automated feeding robots (AFR) are increasingly being used on North American dairy farms to reduce dependency on human labor for feeding. These systems mix, deliver, and push up feed to cows at any frequency or interval desired, allowing for more frequent feed delivery than conventional feeding systems (CFS). This observational study investigated differences in ration consistency, milk components, milk fatty acid profile, and cow behavior between herds using AFR and those using CFS. Sixteen commercial dairies with automated milking systems (AMS) in the upper Midwest United States were paired based on herd size and location into eight blocks each consisting of one CFS and one AFR herd. Feed bunk samples were collected at four equally spaced time points for 3 consecutive d and analyzed for coefficient of variation (CV) of nutrient composition and particle size distribution. Bulk tank milk samples were collected 1 ×/d for 3 d and analyzed for fat, protein, milk urea nitrogen (MUN), lactose, and milk fatty acid (FA) profile. Daily AMS visit intervals, milk yield and composition, and rumination time data were collected from AMS software. A linear mixed model tested fixed effects of feeding system, block, and the random effect of day nested within block. The CV of feed bunk DM, ADF, NDF, and lignin was lower in AFR. Bulk tank milk fat, protein, and MUN were not different between AFR or CFS. AFR had a greater proportion of de novo synthesized FA, but no difference in preformed or mixed FA. Herds with AFR had a shorter AMS visit interval with more AMS refusals per day than CFS. Results imply that AFR may be associated with lower daily variation in fiber concentration at the feed bunk, increased mammary de novo fatty acid synthesis, and increased frequency of cow visits to the AMS compared to conventional PMR feeding. Full article