Technical Note: Effect of Sample Processing Procedures on Measurement of Starch in Corn Silage and Corn Grain

Methods for processing feedstuffs before analysis can affect analytical results. Effects of drying temperature (corn silage), preservation method (corn grain), and grinding method (corn silage and grain) on starch analysis values were evaluated. Corn silage samples dried at 55 or 105°C and grain samples dried at 55°C were ground to pass the 1-mm screen of an abrasion mill or cutting mill and analyzed for free glucose and starch corrected for free glucose. Starch analyses were performed in triplicate to assess the effect of treatment on precision of starch determination. Drying at 105°C decreased free glucose and tended to decrease starch detected in silage. Decreased free glucose and starch values in silages dried at 105°C may have been caused by the destruction of glucose and production of Maillard products through nonenzymatic browning. Maillard products with reducing activity could potentially interfere with the glucose oxidase-peroxidase glucose detection method used. Compared with the cutting mill, grinding samples through the abrasion mill increased the precision of starch measures in silage, likely due to the effect of the finer particle size produced by the abrasion mill allowing more accurate subsampling of a more homogeneous matrix. Starch values were greater for grain ground with an abrasion mill than with a cutting mill, with the difference greater for dry-rolled than for high-moisture corn. For starch analysis of corn silage and corn grain, drying at lower temperatures (55°C) in forced-air ovens and grinding through the 1-mm screen of an abrasion mill or its equivalent is recommended.     

Technical note: Determination of corn hardness in diverse corn germplasm using near-infrared reflectance baseline shift as a measure of grinding resistance

Vitreousness and Stenvert kernel hardness characteristics in corn germplasm have been related to in situ and in vivo starch digestibility in lactating dairy cows. Because of the tedious nature of determining vitreousness by manual dissection or conducting Stenvert hardness measurements, it is challenging to screen corn germplasm for animal performance potential. The resistance of corn to grinding is typically measured in a Stenvert mill and quantified by grinding time and column height. The baseline shift (BLS) of near-infrared reflectance spectroscopy, which is a normal artifact of grinding-induced particle size differentiation, was calculated and evaluated as an alternative measure of grinding resistance. Stenvert grind time, column height, BLS, and ruminal DM degradability (RDMD) of 31 diverse corn germplasm harvested in triplicate at 2 maturities were made. After grinding, total and 6 partial (100 nm) BLS were calculated [Σ x_i + x_j…, where x_i = log₁₀(1/R) at the ith nanometer and R = reflectance] and compared with vitreousness, Stenvert grinding time, column height, or RDMD of corns using correlation and regression procedures. Total and all partial BLS were correlated with vitreousness, Stenvert measures, and RDMD. Relationships between BLS and vitreousness, Stenvert measures, or RDMD were stronger for partial BLS at shorter near-infrared wavelengths (1,080-1,180 nm) than at longer wavelengths (i.e., 2,280-2,380 nm) or total near-infrared BLS (1,000-2,498 nm). The partial BLS from 1,080 to 1,180 nm and vitreousness were better related to RDMD of corn germplasm than Stenvert grind time or column height.     

Technical note: A new facility for continuous respiration measurements in lactating cows

An open-circuit indirect calorimetry system consisting of 4 climate-controlled respiration chambers for cattle has been constructed and validated. The system allows for the continuous monitoring of O₂, CO₂, and CH₄ concentrations in chamber air, and the simultaneous determination of feed and water intake, overall physical activity, position changes, standing and lying times, and animal behavior. For complete balance trials, feces, urine, and milk can be collected quantitatively. Most importantly, lactating cows can be milked in the chamber, and blood samples can be drawn from permanent catheters without disruption of the measurements. The investigator, on entering the chamber, wears a facemask connected to the ambient air during the whole milking process. Data are routed to a data acquisition system with appropriate data evaluation software developed in our research unit. Thus, dynamic changes of the above-named parameters during the course of the day or of longer time periods can be monitored. Such data are critical for understanding the complex regulation and interplay of feed intake, energy metabolism, climatic conditions, and milk production.     

Technical note: Use of accelerometers to describe gait patterns in dairy calves

Developments in accelerometer technology offer new opportunities for automatic monitoring of animal behavior. Until now, commercially available accelerometers have been used to measure walking in adult cows but have failed to identify walking in calves. We described the pattern of acceleration associated with various gaits in calves and tested whether measures of acceleration could be used to count steps and distinguish among gait types. A triaxial accelerometer (sampling at 33 readings/s with maximum measurement at ±3.2 g) was attached to 1 hind leg of 7 dairy calves, and each calf was walked to a familiar large arena (29.1 × 4.8 m) and encouraged to walk and run for 8 to 10 min while being video recorded. The video recordings were watched in slow motion and a total of 54 recordings of 3 to 6 s duration of either galloping (n = 21), trotting (n = 13), or walking (n = 21) were identified and the number of steps were counted. Accelerometer data was then analyzed for each gait. Steps could be clearly identified by changes in the acceleration in the forward and vertical axes and vector sum, but less clearly in the lateral axis. The number of steps counted using the forward axis was highly correlated with the number observed from the video recordings. Galloping, trotting, and walking differed significantly in the median interpeak intervals in acceleration in the forward axis and in the vector sum of the acceleration in the 2 axes. Interpeak intervals could be used to discriminate among the 3 gaits, although walking was most clearly distinguished from galloping. Automated measures of acceleration of the leg in the forward and vertical dimensions can be used to count steps and classify gaits of calves.     

Technical note: A novel approach to the detection of estrus in dairy cows using ultra-wideband technology

Detection of estrus is a key determinant of profitability of dairy herds, but estrus is increasingly difficult to observe in the modern dairy cow with shorter duration and less-intense estrus. Concurrent with the unfavorable correlation between milk yield and fertility, estrus-detection rates have declined to less than 50%. We tested ultra-wideband (UWB) radio technology (Thales Research & Technology Ltd., Reading, UK) for proof of concept that estrus could be detected in dairy cows (two 1-wk-long trials; n = 16 cows, 8 in each test). The 3-dimensional positions of 12 cows with synchronized estrous cycles and 4 pregnant control cows were monitored continuously using UWB mobile units operating within a network of 8 base units for a period of 7 d. In the study, 10 cows exhibited estrus as confirmed by visual observation, activity monitoring, and milk progesterone concentrations. Automated software was developed for analysis of UWB data to detect cows in estrus and report the onset of estrus in real time. The UWB technology accurately detected 9 out of 10 cows in estrus. In addition, UWB technology accurately confirmed all 6 cows not in estrus. In conclusion, UWB technology can accurately detect estrus and hence we have demonstrated proof of concept for a novel technology that has significant potential to improve estrus-detection rates.     

Technical note: Rapid method for determination of amino acids in milk

A rapid method for measurement of amino acids in milk was developed and validated. The method included a first step of milk protein hydrolysis, followed by the derivatization and separation of amino acids by HPLC. Six combinations of hydrolysis agent and temperature-time conditions were compared with a reference method; derivatization procedures as well as HPLC separation were improved. Hydrolysis of milk samples with 6 N HCl at 160°C for 60 min resulted in no significantly differences compared with the reference method but allowed the analysis of a greater number of milk samples in a short time. In addition, this method was characterized by high precision, low repeatability uncertainty, and high accuracy for all amino acids evaluated; the recovery mean value of the single amino acids was 98.38%. The proposed method is, therefore, accurate, simple, rapid, and suitable for large numbers of milk samples.     

Technical note: A new high-performance liquid chromatography purine assay for quantifying microbial flow

An HPLC method was developed to quantify the purines adenine and guanine and their metabolites xanthine and hypoxanthine in hydrolysates of isolated bacteria and omasal digesta and to assess the effect of using either purines only or purines plus metabolites as microbial markers for estimating microbial flow from the rumen. Individual purines and their metabolites were completely resolved on a C18 column using gradient elution with 2 mobile phases. Intraassay coefficient of variation ranged from 0.6 to 3.1%. Hydrolytic recovery of the 4 purine bases from their corresponding nucleosides averaged 101% (control), 103% (when added to bacterial isolates), and 104% (when added to omasal digesta). Mean concentrations of adenine, guanine, xanthine, and hypoxanthine were, respectively, 53, 58, 2.8, and 3.5 μmol/g of dry matter in omasal bacteria and 10, 12, 7.5, and 7.5 μmol/g of dry matter in omasal digesta, indicating that xanthine plus hypoxanthine represented 5% of total purines in bacterial hydrolysates but 41% of total purines in digesta hydrolysates. A significant negative relationship (R² = 0.53) between the sum of adenine and guanine and the sum of xanthine and hypoxanthine in digesta samples (but not bacterial isolates) indicated that 89% of the adenine and guanine originally present in ruminal microbes were recovered as xanthine and hypoxanthine. These results suggested that, when total purines are used as the microbial marker, both purines and their metabolites should be quantified and used to compute microbial nonammonia N and organic matter flows.     

Technical note: A comparison of 2 methods of assessing lameness prevalence in tiestall herds

We compared 2 methods for identifying lame cows and estimating the prevalence of lameness in tiestalls. Cows (n = 320) in 9 tiestall herds were scored as lame both by the presence of limping while walking and by stall lameness scores (SLS). The SLS was based on the number of the following behaviors that the cow showed while standing in the tiestall: weight shifting, standing on the edge of the stall, uneven weight bearing while standing, and uneven weight bearing while moving from side to side. Two observers watched video-recordings of the cows. Intraobserver agreements for the 4 SLS behaviors ranged from 92 to 100%, and interobserver agreement ranged from 81 to 100%. The overall prevalence of lameness based on an SLS of ≥2 was similar to that of limping (39 vs. 40%). The sensitivity of the classification based on the SLS was 0.63 and the specificity was 0.77 in identifying cows with a limp; accuracy varied across farms from 62.2 to 80.4%, with a mean of 71.7%. A cow with an SLS of ≥2 had 4.88 times the odds of limping than a cow with an SLS of <2. The prevalence of lameness on farms based on SLS was highly correlated with the prevalence of limping (Pearson correlation = 0.88; n = 9), and prevalence estimates from the 2 methods diverged most when the mean herd prevalence was lower. The SLS method provides an estimate of the prevalence of lameness in tiestall herds comparable with traditional gait scoring, but does not require that the cows be untied. The SLS method could be used to improve lameness detection on tiestall farms and obtain estimates of lameness prevalence without the need to walk the cows.     

Technical note: Development of a challenge model for Streptococcus uberis mastitis in dairy heifers

A challenge model for experimentally inducing Streptococcus uberis mastitis in bred dairy heifers was developed. Qualifying heifers (n = 7) exhibited antibody titers of < 1:10,000 against Strep. uberis antigens and were free of intramammary infections (IMI). Two contralateral quarters of each heifer were assigned to receive an infusion of Strep. uberis (1,000 to 2,000 cfu); remaining quarters served as unchallenged controls. For a successful challenge and infection, 3 of 4 consecutive mammary secretion samples had to culture positive for Strep. uberis. Six of the 7 heifers were challenged successfully in both infused quarters with a mean dose of 1,080 cfu; once confirmed, infections were treated with a one-time infusion of nonlactating cow therapy. Before challenge, mammary secretion leukocyte counts averaged 8.4 × 10⁶/mL in all quarters. At 24 h after challenge, leukocyte count increased to 18.4 × 10⁶/mL in challenged quarters, peaking on d 5 at 24.3 × 10⁶/mL; unchallenged quarters remained at ≤ 10.4 × 10⁶/mL, but increased to 15.2 × 10⁶/mL on d 7 and then decreased. Before challenge, macrophages predominated (81%) in mammary secretions followed by lymphocytes (15.3%) and neutrophils (3.7%). By 24 h after challenge, neutrophils increased in challenged quarters and predominated for the duration of the trial (65.3 to 70%), whereas macrophages predominated in unchallenged control quarters (65.2 to 75.2%). The challenge model was successful in establishing Strep. uberis IMI in 85.7% of animals, and IMI were controlled (100% cure) by administering nonlactating cow therapy. All heifers calved free of IMI and antimicrobial residues, with milk production similar to that of herd mates and with somatic cell counts (SCC) < 200,000 cells/mL.     

Technical note: A simple model to estimate changes in dietary composition of strip-grazed cattle during progressive pasture defoliations

Methodological problems occur in measuring herbage intake and diet quality during short-term (4-24 h) progressive defoliations by grazing. Several models were developed to describe pasture component selection by grazing ruminants, particularly sheep. These models contain empirical coefficients to determine preferences that require laborious and data-demanding calibration. The objective was to develop a simple and practical model of changes in diet composition (green:dead) of pastures strip-grazed by dairy cows. The model was based on 3 premises when cows are strip-grazed in relatively homogeneous swards: 1) cows eat dead material only when green leaf and uncontaminated material have been removed; 2) dead material increases toward the bottom of the sward canopy; and 3) cows progressively defoliate pasture in layers. The main simplification in this model was assuming a linear decrease of green mass from the top to the bottom of the sward canopy. Thus, the proportion of green mass in the stratum eaten depended on the proportion of green in the entire sward canopy and its vertical profile. The model offers a simple solution to estimate changes in dietary compositions in pastures strip-grazed by dairy cattle during progressive pasture defoliations. It uses 2 inputs, the green mass proportion of the total herbage mass and the proportion of total herbage mass eaten during grazing. This can be optionally complemented with inputs of herbage chemical composition. The main outputs of the model are the proportions of green and dead herbage mass in the diet. For example, if the green proportion in the sward was 0.5 and the proportion of herbage mass eaten was 0.5, then the diet would be 0.75 green:0.25 dead; assuming 0.8 and 0.4 digestibility for green and dead material, respectively, the diet digestibility would be 0.7.     

Technical note: A mathematical function to predict daily milk yield of dairy cows in relation to the interval between milkings

The milk production of a dairy cow is characterized by lactation production, which is calculated from daily milk yields (DMY) during lactation. The DMY is calculated from one or more milkings a day collected at the farm. Various milking systems are in use today, resulting in one or many recorded milk yields a day, from which different calculations are used to determine DMY. The primary objective of this study was to develop a mathematical function that described milk production of a dairy cow in relation to the interval between 2 milkings. The function was partly based on the biology of the milk production process. This function, called the 3K-function, was able to predict milk production over an interval of 12 h, so DMY was twice this estimate. No external information is needed to incorporate this function in methods to predict DMY. Application of the function on data from different milking systems showed a good fit. This function could be a universal tool to predict DMY for a variety of milking systems, and it seems especially useful for data from robotic milking systems. Further study is needed to evaluate the function under a wide range of circumstances, and to see how it can be incorporated in existing milk recording systems. A secondary objective of using the 3K-function was to compare how much DMY based on different milking systems differed from that based on a twice-a-day milking. Differences were consistent with findings in the literature.     

Technical note: Evaluation of a scoring system for rumen fill in dairy cows

Changes in feed intake are useful in early detection of disease in dairy cows. Cost and complexity limit our ability to monitor dry matter intake (DMI) of individual cows kept in loose-housing systems. A 5-point subjective scoring system has been developed to visually describe rumen fill, but no work to date has evaluated these scores as an indicator of feed intake. The objective of this study was to evaluate the performance of within-cow changes in visual rumen fill scores as estimates of changes of DMI and feed intake in dairy cows. Our results illustrate that rumen fill scored on a scale from 1 to 5 has substantial intra- (Cohen's kappa coefficient = 0.69) and interobserver (Cohen's kappa coefficient = 0.68) repeatability. Within-cow changes in visual rumen fill score are correlated with changes in DMI (Spearman's rank correlation = 0.68). The depth of the paralumbar fossa (mean ± SD; 5.6 ± 0.9 cm) changes considerably (up to 4.8 cm) within 70 ± 5 min. This more objective measure was also correlated with visual rumen fill scores (Spearman's rank correlation = −0.62). Our results indicate that subjective rumen fill scores are statistically associated with both an objective measure of paralumbar fossa indentation and feed intake. However, much of the variation in visual rumen fill scores is not associated with either measure, suggesting that caution is required in clinical usage of these scores.     

Technical note: A rapid enzyme-linked immunosorbent assay blood test for pregnancy in dairy and beef cattle

The ruminant trophoblast produces pregnancy-associated glycoproteins (PAG) that can be detected in the blood of pregnant animals. The objective was to determine the accuracy of a rapid ELISA PAG-based test for the purpose of pregnancy detection in cattle. Blood was sampled from dairy cattle (539 Holstein cows, 173 Holstein heifers, 73 Guernsey cows, 22 Guernsey heifers, and 12 Jersey heifers) and crossbred beef cattle (145 cows and 46 heifers) that were ≥25 d after insemination (range = 25 to 45 d for dairy and 29 to 56 d for beef). Cattle were examined by ultrasonography for detection of pregnancy within 2 d of blood collection. Whole blood or plasma was incubated in a polystyrene tube coated with a monoclonal PAG antibody for 15 min. The tubes were then washed and subjected to sequential incubations with a biotinylated polyclonal PAG antibody (15 min, followed by wash), a horseradish peroxidase-streptavidin solution (15 min, followed by wash), and a peroxidase substrate. Tubes were visually assessed for color after 15 min (clear solution = PAG negative, not pregnant; blue solution = PAG positive, pregnant). Total assay time was approximately 90 min. The ultrasound examination was used as the standard for pregnancy diagnosis. The sensitivity (99.8 ± 0.2%), specificity (91.7 ± 1.4%), and negative predictive value (99.7 ± 0.3%) for the PAG test used in dairy cattle were similar for different breeds and for cows and heifers. The positive predictive value for the test was greater in dairy heifers than in dairy cows (96.5 ± 1.4% vs. 90.5 ± 1.7%, respectively). In beef cattle, the sensitivity (100%), specificity (92.3 ± 3.0%), positive predictive value (95.0 ± 2.0%), and negative predictive value (100%) for the PAG test were similar for cows and heifers. The accuracy of the test was not different for dairy and beef cattle. In conclusion, the rapid ELISA pregnancy test based on PAG was highly sensitive and specific for pregnancy detection in dairy and beef cattle.     

Technical note: Evaluation of an ear-attached movement sensor to record cow feeding behavior and activity

The ability to monitor dairy cow feeding behavior and activity could improve dairy herd management. A 3-dimensional accelerometer (SensOor; Agis Automatisering BV, Harmelen, the Netherlands) has been developed that can be attached to ear identification tags. Based on the principle that behavior can be identified by ear movements, a proprietary model classifies sensor data as “ruminating,” “eating,” “resting,” or “active.” The objective of the study was to evaluate this sensor on accuracy and precision. First, a pilot evaluation of agreement between 2 independent observers, recording behavior from 3 cows for a period of approximately 9 h each, was performed. Second, to evaluate the sensor, the behavior of 15 cows was monitored both visually (VIS) and with the sensor (SENS), with approximately 20 h of registration per cow, evenly distributed over a 24-h period, excluding milking. Cows were chosen from groups of animals in different lactation stages and parities. Each minute of SENS and VIS data was classified into 1 of 9 categories (8 behaviors and 1 transition behavior) and summarized into 4 behavioral groups, namely ruminating, eating, resting, or active, which were analyzed by calculating kappa (κ) values. For the pilot evaluation, a high level of agreement between observers was obtained, with κ values of ≥0.96 for all behavioral categories, indicating that visual observation provides a good standard. For the second trial, relationships between SENS and VIS were studied by κ values on a minute basis and Pearson correlation and concordance correlation coefficient analysis on behavior expressed as percentage of total registration time. Times spent ruminating, eating, resting, and active were 42.6, 15.9, 31.6, and 9.9% (SENS) respectively, and 42.1, 13.0, 30.0, and 14.9% (VIS), respectively. Overall κ for the comparison of SENS and VIS was substantial (0.78), with κ values of 0.85, 0.77, 0.86, and 0.47 for “ruminating,” “eating,” “resting,” and “active,” respectively. Pearson correlation and concordance correlation coefficients between SENS and VIS for “ruminating,” “eating,” “resting,” and “active” were 0.93, 0.88, 0.98, and 0.73, and 0.93, 0.75, 0.97, and 0.35, respectively. In conclusion, the results provide strong evidence that the present ear sensor technology can be used to monitor ruminating and resting behavior of freestall-housed dairy cattle. Our results also suggest that this technology shows promise for monitoring eating behavior, whereas more work is needed to determine its suitability to monitor activity of dairy cattle.     

Technical note: Comparing calibration methods for determination of protein in goat milk by ultraviolet spectroscopy

A rapid spectroscopic method to determine total protein in bovine and buffalo milk using UV spectra of guanidine-hydrochloride mixed milk has previously been reported and validated. The method was based on mixed calibration samples and univariate calibrations of fourth derivative (4D) spectra. In this study the same method was compared and tested for determination of total protein in goat milk. Calculations based on multivariate calibration (partial least squares regression) on full spectra of goat milk were used. The method was tested on 2 UV instruments. The comparison resulted in a significantly more robust (i.e., better) transferability between UV instruments for the partial least squares regression method on full spectra compared with previous univariate calibration of 4D spectra. Local (1 instrument) calibrations gave similar, significantly not different (chi-squared test) cross-validated prediction error results for the 2 methods. It can be concluded that there is no need for fourth derivation. Partial least squares regression on full spectra was equal or superior to using the 4D spectra.     

Technical note: A noninvasive urine collection device for female cattle: Modification of the urine cup collection method

Total urine collection from female cattle requires the use of indwelling urinary catheters or an external device requiring secure attachment with adhesive to the animal; neither method is ideal for the welfare of the cattle. A urine collection device was developed to enable total urine collection in female dairy cattle without the use of adhesive to attach the device to the vulva of the animal; the device was a modification of one described previously for female cattle. The urine collection device was made from polypropylene with maximum dimensions (height × width × depth) of 17.5 × 11.0 × 6.0 cm and an opening of approximately 42 cm² to cover the vulva. The device was secured using a commercially available udder support harness that provided snap-fasteners and support for the device to be positioned at the level of the vulva. At the point of attachment, a metal brace surrounded the device and was connected to the udder support by metal rings, which kept the urine cup in proper position as the animal arched to urinate. A metal O-clamp and pieces of rubber, serving as leak-proof washers, connected the bottom of the device to Gooch tubing. Another metal clamp was attached to a polyvinyl chloride adapter that was connected to a rubber hose, and urine was collected into carboys located on the floor approximately 1.5 m behind the animals. This modification of a urine cup allows several noninvasive total feces and urine collection studies of unrestricted length to be undertaken without the use of adhesive to attach the device. The floor-level collection system is a practical, portable, and handy system that will permit researchers to perform nutrient balance and metabolic studies on female cattle.     

Technical note: Variation in daily milk yield calculations for dairy cows milked in an automatic milking system

An accurate estimation of the daily milk yield of dairy cows milked in an automatic milking system is not obvious because of variations in milking intervals and frequencies. Daily harvested milk varies substantially, and developing a method to be used for estimating daily milk production is of great importance. Three calculation methods (simple, semiadvanced, and advanced) were used. The simple method calculated rough daily milk production by summing up the yield per day. The semiadvanced used yield in combination with time since last milking to calculate the milk production per hour between milking; an average of the milk production per hour over the day was calculated and multiplied by 24. The advanced method calculated the milk production from midnight to midnight by using information about yield and time since last milking to calculate the exact milk production. The results show a clear preference for the advanced calculation method because the variation [variation for the advanced method = ln(1.79) for first lactation and ln(2.28) for later lactations] between days was reduced significantly (3 to 4 times lower compared with the simple method). Variation in daily harvested milk can be used as a management tool.     

Technical note: Evaluation of procedures for analyzing ration sorting and rumen digesta particle size in dairy cows

Collecting total mixed ration (TMR) samples throughout the day to measure sorting activity of dairy cows may cause changes to the sorting behavior of cows or may make it more difficult to elucidate effects of sorting on TMR particle size distributions. Also, forage particle size research commonly includes analysis of the solid portion of rumen digesta for particle size distribution after digesta has been squeezed through several layers of cheesecloth. Therefore, the first objective of this experiment was to determine if collecting TMR samples throughout the day affected sorting behavior of cows and resulted in a different particle size distribution than when TMR was not artificially altered during the day. The second objective of this experiment was to determine if squeezing rumen digesta samples through cheesecloth changed particle size distribution when analyzed by a wet sieving technique. It was determined that small, significant differences existed in particle size distribution between the 2 sampling methods of TMR for sorting behavior. These differences were more likely to occur at time points later in the day. This resulted in small changes in sorting indices calculated from these data; sampling and mixing TMR throughout the day reduced the degree of sorting. Squeezing rumen digesta through 4 layers of cheesecloth had no effect on particle size distribution of particles >0.15 mm but reduced the amount of rumen fluid-associated dry matter contained in the sample.     

Hot topic: Pathway confirmed for the transmission of melamine from feed to cow's milk

Eight lactating Holstein cows were randomly allotted to 2 groups in a trial to establish whether a pathway exists for the transmission of melamine from feed to milk. All cows received oat hay ad libitum and 15 kg of concentrate pellets per cow daily. The concentrate pellets contained either melamine-contaminated corn gluten meal of Chinese origin (melamine treatment) or locally produced melamine-free corn gluten meal (control treatment). Cows in the melamine treatment ingested 17.1 g of melamine per day. Cows were milked twice daily, and milk samples were taken once daily during the afternoon milking for melamine and milk component analyses. Melamine appeared in the milk within 8 h after first ingestion of the melamine containing pellets. Melamine concentration reached a maximum of 15.7 mg/kg within 56 h after first ingestion, with an excretion efficiency of approximately 2%. Milk solids and milk urea nitrogen were not affected by treatment. The melamine concentration dropped rapidly after changing all cows back to the control pellets, but melamine only declined to undetectable levels in the milk more than 6 d (152 h) after last ingestion of melamine. Results from the current trial are important to the feed and dairy industries because, until now, any melamine found in milk and milk products was attributed only to the deliberate external addition of melamine to these products, not to adulterated ingredients in animal feeds.