Relationships between farm and animal factors and the fatty acid (FA) profile and milk amyloid A (MAA) content of milk were determined in 336 Holstein dairy cows on 24 Quebec farms using multiple regression. Cows with a somatic cell count (SCC) >200 000, and farms feeding palm oil were excluded. Independent factors of the regression models included days in milk (DIM), parity, yield, fat and protein contents of milk, SCC, and the dietary contents of neutral detergent fiber (NDF) and crude fat (CFAT). Nonsignificant variables with P > 0.25 were stepwise removed. Models with high fits were those of total short-chain FA, medium-chain FA, odd- and branched-chain FA (OBCFA), and saturated long-chain FA with R2 of 0.33, 0.36, 0.34, and 0.41, respectively. The fat and protein contents and yield of milk did not affect the milk FA profile. Higher NDF increased the milk fat proportions of short-chain FA and OBCFA and decreased those of monounsaturated (MUFA) and polyunsaturated FA (PUFA). Higher CFAT reduced this proportion of short-chain FA but increased those of MUFA and PUFA. Increasing DIM reduced this proportion of short-chain FA and increased that of medium-chain FA. Higher SCC increased MAA.

This article focuses on the creation of a monitoring tool using routinely collected data from milk payment analyses. Milk samples were analyzed through Fourier Transform mid-infrared spectrometry every 1 to 3 days, and their compositions were predicted using machine learning models. Among the predicted parameters, fatty acid profiles appear to be effective indicators of animal status and management practices. In this research, these profiles were summarized using 31 fatty acids or groups of fatty acids. The methodology consists of four steps: hierarchical clustering to detect patterns in a Belgian spectral dataset (N = 774,781), interpretation of the identified seven clusters, development of predictive models applied to a Canadian dataset (N = 670,165), and validation using management information collected from Canadian farms. The identified clusters revealed significant relationships with feeding management strategies and temporal evolutions, highlighting the potential to develop automated alert systems that assist farmers and advisors in herd monitoring.

This closed cohort study aimed to identify the associations between dairy calf management practices and herd-level perinatal calf mortality risk. From February 2020 to June 2021, predominantly Holstein dairy farms in Québec (n = 1832) and New Brunswick (n = 52), Canada, registered in the dairy herd improvement program, were visited once. A questionnaire covering all aspects of precalving, calving, and colostrum management was administered. Data regarding perinatal mortality were retrieved from the dairy herd improvement program database for each farm for 2021. Perinatal mortality was calculated for each farm as the proportion of calves dead at birth or dying within 24 h of life. A multivariable negative binomial model was used to assess herd-level factors associated with the risk of perinatal mortality. The final model included the lying surface in the calving area, the typical time to first colostrum intake, typical cow-calf contact time, the proportion of males born, the proportion of assisted calvings, and herd size. Herd-level perinatal mortality risk ranged from 0 to 38.1% (mean (SE) = 7.6% ± 0.1%). A greater proportion of males born, proportion of assisted calvings, and delayed colostrum feeding were associated with increased herd-level perinatal mortality. Factors associated with a decreased herd–level perinatal mortality risk were having a typical cow-calf contact time between 7 and 12 h after calving compared with reduced cow-calf contact time, soft lying surfaces in the calving area compared with concrete and mat-lying surfaces, and an increased number of calvings per year. Our results show that while some of the significant risk factors are not well understood (i.e., calving area lying surface, typical cow-calf contact time); Canadian farmers could focus on the factors under their control (i.e., time to first colostrum feeding, proportion of difficult calvings, males born, and calvings per year) to reduce the risk of perinatal mortality. Future work should focus on qualitative research to understand the dairy farmer motivations and limitations to implementing practices identified in this and other studies to reduce perinatal mortality.

The whole milk or milk replacer (MR) intake by dairy heifers during their preweaning period is known to have an impact on their early and long-term development, growth, and productivity. The objective of this study was to assess whether providing ad libitum access to MR in comparison to the Canadian milk feeding recommendation would impact growth performance during the preweaning period, and if those impacts would be maintained in the postweaning period, near puberty at around 11 months of age. On a commercial farm located in Quebec, Canada, 179 Holstein heifers were randomly assigned to two treatments where they were offered (1) ad libitum access to MR (AdLib, n = 93) or (2) a maximum amount of MR corresponding to 20% of their birth weights as currently recommended by the Canadian Code of Practice for the Care and Handling of Dairy Cattle (ReCan, n = 86). Weaning started at 52 and 64 d of age for AdLib and ReCan, respectively, and was completed at 76 d of age for both treatments. Milk replacer (28% CP, 16% fat, 15% DM) was offered using an automated feeding system, and the amount of MR was gradually reduced at weaning, over 24 and 12 d for AdLib and ReCan, respectively, with an identical program for the last 12 d. Data were collected for individual heifers to obtain live BW, heart girth circumference, withers height, hip height, and hip width during the preweaning (55 d) period and around puberty (around 11 mo). Mean MR intake at peak consumption between 46 d and 52 d was 11.8 L/d for AdLib vs 8.3 L/d for ReCan. Our results show that heifers on the AdLib treatment had significantly higher BW at 55 d of age and around puberty compared to heifers on the ReCan treatment. At weaning, no significant differences were observed for heart girth circumference, withers height, hip width, or average daily gain (ADG). Near puberty, the BW and hip height are significantly higher for the AdLib heifers and, when considering only heifers consuming a minimal amount of 7.5 L/d at the peak of consumption for the analysis, heart girth circumference, and ADG are significantly higher as well. Our results indicate that preweaning body conformation gains associated with an AdLib feeding program are maintained until puberty and this is even when compared to the current Canadian milk feeding recommendation of 20% of live weight in MR.

The objective of this study was to examine the influence of different environmental factors on ATP luminometry measurements of feeding equipment and to investigate associations with health of preweaning calves and the levels of ATP identified through luminometry. On 50 commercial dairy farms in Quebec, Canada, ATP luminometry measurements (in relative light units, RLU) were obtained using the direct swabbing technique with Hygiena UltraSnap swabs and a liquid rinsing technique with the same swab for automatic milk feeders (AMF), bottles, buckets, esophageal tube feeders (ET), milk replacer, nipples, and water. During this visit, environmental factors (including temperature, air draft, humidity, ammonia, and bacterial count) were collected, and a clinical examination (including respiratory score and fecal score) was performed for all preweaning calves present at the farm. This process was repeated 4 times in a year, leading to collection of luminometer results, environmental parameters, and overall health of calves for each season per farm. Overall, a difference in luminometer results was seen between the different periods sampled for all feeding equipment (except the ET), milk replacer, and water, showing higher RLU values in spring and summer and lower values in autumn and winter. When comparing RLU measurements with environmental factors, only a low to negligible correlation could be found. When feeding equipment was classified as not contaminated or contaminated based on previously described cutoff values, a good agreement within a farm for the different seasons was noticed only for nipples (Gwet's agreement AC1 = 0.64), with a poor to moderate agreement for other feeding equipment. Regarding the different models of nipples, Peach Teat nipples showed higher RLU values compared with Merrick's nipples. An association was seen between the proportion of pre- weaning calves suffering from diarrhea on the farm and the contamination of AMF based on ATP luminometry (logistic regression estimate = 0.52). For other feeding equipment, milk replacer, and water, no significant associations were found. This study showed that ATP luminometry measurements of feeding equipment from preweaning calves are susceptible to seasonality and type of nipple. Thus, these factors should be taken into consideration when interpreting results. Additionally, an association could be made between diarrhea in preweaning calves and the contamination of AMF based on ATP luminometry, showing the potential clinical importance of this on-farm hygiene assessment tool.

The goal of this study was to isolate spectral fingerprints from milk Fourier transform infrared spectra that may reflect potential improvements in cow welfare, specifically comfort and ease of movement, resulting from modified housing configurations. Housing configuration modification treatments were tested across 3 animal trials, consisting of modified chain length (TCL), stall width (SW) and manger wall and stall length (MW/SL) configurations. The spectral analyses involved the use of principal components and mixed model analysis. Principal components were calculated from averages of mid-infrared spectra collected on the last weeks of treatment application in each of the animal trials. A significant effect of housing configuration was revealed. As an indication of animal comfort improvement, milk of cows assigned to longer chains revealed a trend of changes in multiple milk components (e.g., milk NPN, trans fatty acids, fat, and protein) that are consistent with changes in ruminal pH. These conclusions were inline with those drawn from the analysis of animal-based responses such as behavioral data and other outcomes. This study was able to reveal that housing modifications had a significant effect on milk spectra, with differences observed between the most and least restrictive treatments, translating into improved or reduced animal welfare status.

Our objective was to validate the possibility of detecting SARA from milk Fourier transform mid-infrared spectroscopy estimated fatty acids (FA) and machine learning. Subacute ruminal acidosis is a common condition in modern commercial dairy herds for which the diagnostic remains challenging due to its symptoms often being subtle, nonexclusive, and not immediately apparent. This observational study aimed at evaluating the possibility of predicting SARA by developing machine learning models to be applied to farm data and to provide an estimated portrait of SARA prevalence in commercial dairy herds. A first data set composed of 488 milk samples of 67 cows (initial DIM = 8.5 ± 6.18; mean ± SD) from 7 commercial dairy farms and their corresponding SARA classification (SARA+ if rumen pH <6.0 for 300 min, else SARA-) was used for the development of machine learning models. Three sets of predictive variables: i) milk major components (MMC), ii) milk FA (MFA), and iii) MMC combined with MFA (MMCFA) were submitted to 3 different algorithms, namely Elastic net (EN), Extreme gradient boosting (XGB), and Partial least squares (PLS), and evaluated using 3 different scenarios of cross-validation. Accuracy, sensitivity, and specificity of the resulting 27 models were analyzed using a linear mixed model. Model performance was not significantly affected by the choice of algorithm. Model performance was improved by including fatty acids estimations (MFA and MMCFA as opposed to MMC alone). Based on these results, one model was selected (algorithm: EN; predictive variables: MMCFA; 60.4, 65.4, and 55.3% of accuracy, sensitivity, and specificity, respectively) and applied to a large data set comprising the first test-day record (milk major components and FA within the first 70 DIM of 211,972 Holstein cows (219,503 samples) collected from 3001 commercial dairy herds. Based on this analysis, the within-herd SARA prevalence of commercial farms was estimated at 6.6 ± 5.29% ranging from 0 to 38.3%. A subsequent linear mixed model was built to investigate the herd-level factors associated to higher within-herd SARA prevalence. Milking system, proportion of primiparous cows, herd size and seasons were all herd-level factors affecting SARA prevalence. Furthermore, milk production was positively, and milk fat yield negatively associated with SARA prevalence. Due to their moderate levels of accuracy, the SARA prediction models developed in our study, using data from continuous pH measurements on commercial farms, are not suitable for diagnostic purpose. However, these models can provide valuable information at the herd level.

The objectives of this study were to determine the farm-level hyperketolactia (HKL) prevalence, as diagnosed from milk β-hydroxybutyrate (BHB) concentration, on dairy farms milking with an automatic milking system (AMS) and to describe the farm-level housing, management, and nutritional risk factors associated with increased farm-average milk BHB and the within-herd HKL prevalence in the first 45 DIM. Canadian AMS farms (n = 162; eastern Canada n = 8, Quebec n = 23, Ontario n = 75, western Canada n = 55) were visited once between April to September 2019 to record housing and herd management practices. The first test milk data for each cow under 45 DIM were collected, along with the final test of the previous lactations for all multiparous cows, from April 1, 2019 to September 30, 2020. The first test milk BHB was then used to classify each individual cow as having HKL (milk BHB ≥ 0.15 mmol/L) at the time of testing. Milk fat and protein content, milk BHB, and HKL prevalence were summarized by farm and lactation group (all, primiparous, and multiparous). During this same time period, formulated diets for dry and lactating cows, including ingredients and nutrient composition, and AMS milking data were collected. Data from the AMS were used to determine milking behaviors and milk production of each herd during the first 45 DIM. Multivariable regression models were used to associate herd-level housing, feeding management practices, and formulated nutrient composition with first test milk BHB concentrations and within-herd HKL levels separately for primiparous and multiparous cows. The within-herd HKL prevalence for all cows was 21.8%, with primiparous cows having a lower mean prevalence (12.2 ± 9.2%) than multiparous cows (26.6 ± 11.3%). Milk BHB concentration (0.095 ± 0.018 mmol/L) and HKL prevalence for primiparous cows were positively associated with formulated prepartum DMI and forage content of the dry cow diet while being negatively associated with formulated postpartum DMI, the major ingredient in the concentrate supplemented through the AMS, and the PMR-to-AMS concentrate ratio. However, multiparous cows' milk BHB concentration (0.12 ± 0.023 mmol/L) and HKL prevalence were positively associated with the length of the previous lactation, milk BHB at dry off, prepartum diet nonfiber carbohydrate content, and the major forage fed on farm, while tending to be negatively associated with feed bunk space during lactation. This is the first study to determine the farm-level risk factors associated with herd-level prevalence of HKL in AMS dairy herds, thus helping optimize management and guide diet formulation to promote the reduction of HKL prevalence.

The objective of this study was to describe the nutritional strategies used on Canadian dairy farms with automated milking systems (AMS), both at the feed bunk and the concentrate offered at the AMS, as well as to determine what dietary components and nutrients, as formulated, were associated with milk production and milking behaviors on those farms. Formulated diets (including ingredients and nutrient content) and AMS data were collected from April 1, 2019, until September 30, 2020, on 160 AMS farms (eastern Canada [East] = 8, Ontario [ON] = 76, Quebec [QC] = 22, and western Canada [West] = 54). Both partial mixed ration (PMR) and AMS concentrate samples were collected from May 1 to September 30, 2019, on 169 farms (East = 12, ON = 63, QC = 42, West = 52). We collected AMS milking data for 154 herds. For each farm (n = 161), milk recording data were collected and summarized by farm to calculate average milk yield and components. Multivariable regression models were used to associate herd -level formulated nutrient composition and feeding management practices with milk production and milking behavior. Milk yield (mean +/- SD = 37.0 +/- 0.3 kg/d) was positively associated with the PMR ether extract (EE) concentration (+0.97 kg/d per percentage point [ p.p. ] increase) and with farms that fed barley silage as their major forage source (n = 16; +2.18 kg/d) as compared with haylage (n = 42), whereas farms that fed corn silage (n = 96; +1.23 kg/d) tended to produce more milk than farms that fed haylage. Greater milk fat content (4.09 +/- 0.28%) was associated with a greater PMR-to-AMS concentrate ratio (+0.02 p.p. per unit increase) and total diet net energy for lactation (+0.046 p.p. per 0.1 Mcal/kg increase), but a lesser percentage of NFC of the PMR (-0.016 p.p. per p.p. increase of NFC percentage). Milk protein content (3.38 +/- 0.14%) was positively associated with the forage percentage of the PMR (+0.003 p.p. per p.p. increase of forage percentage ) and the total diet starch percentage (+0.009 p.p. per p.p. increase of starch percentage), but was negatively associated with farms feeding corn silage (-0.1 p.p. compared with haylage) as their major forage. Greater milking frequency (2.77 +/- 0.40 milkings/d) was observed on farms with free -flow cow traffic systems (+0.62 milkings/d) and was positively associated with feed push-up frequency (+0.013 milkings/d per additional feed push-up), but negatively associated with PMR NFC content and forage percentage of the total ration (-0.017 milkings/d per p.p. increase of forage percentage). Lastly, greater milking refusal frequency (1.49 +/- 0.82 refusals/d) was observed on farms with free -flow cow traffic systems (+0.84 refusals/d) and farms feeding barley silage (+0.58 refusals/d) than with guided flow and farms feeding either corn silage or haylage, respectively. These data give insight into the ingredients, nutrient formulations and type of diets fed on AMS dairy farms across Canada and the association of those factors with milk production and milking behaviors.

Although there is evidence that ketosis negatively affects fertility, the effect of late and early ketosis on the reproductive performance of lactating cows has not been systematically investigated. The aim of this study was to evaluate the association between time and amplitude of elevated milk BHB (EMB) occurring within 42 d in milk (DIM) and subsequent reproductive performance of lactating Holstein cows. The dairy herd information data of 30,413 cows with 2 test-day milk BHB recordings during early lactation periods 1 and 2 (5-14 and 15-42 DIM, respectively) assessed as negative (<0.15 mmol/L), suspect (0.15-0.19 mmol/L), or positive (≥0.2 mmol/L) for EMB were used in this study. Based on the time and amplitude of milk BHB, cows were grouped into 7 groups: (1) healthy cows negative in both periods 1 and 2 were classified as NEG; (2) suspect in period 1 and negative in period 2: EARLY_SUSP; (3) suspect in period 1 and suspect/positive in period 2: EARLY_SUSP_Pro; (4) positive in period 1 and negative in period 2: EARLY_POS; (5) positive in period 1 and suspect/positive in period 2: EARLY_POS_Pro; (6) negative in period 1 and suspect in period 2: LATE_SUSP; and (7) negative in period 1 and positive in period 2: LATE_POS. The overall prevalence of EMB within 42 DIM was 27.4%, with the highest prevalence being EARLY_SUSP (10.49%). Cows in EARLY_POS and EARLY_POS_Pro, but not other EMB categories, had a longer interval from calving to first service compared with NEG cows. For the reproductive parameters, first service to conception interval, days open and calving interval, cows in all EMB groups except EARLY_SUSP had longer intervals compared with NEG cows. These data indicate that there is a negative association between EMB within 42 d and reproductive performance after the voluntary waiting period. The intriguing findings of this study are the unaltered reproductive performance of EARLY_SUSP cows, and the negative association between late EMB and reproductive performance. Hence, monitoring and prevention of ketosis during the first 6 wk of lactation is necessary to optimize reproductive performance of lactating dairy cows.

The objective of this study was to describe the cleaning practices currently used for preweaning calves on dairy farms in Quebec, Canada. In addition, contamination of feeding equipment for preweaning calves was described using ATP (expressed as relative light units, RLU), visual assessment, and bacteriological analysis. A questionnaire was administered on 50 commercial dairy farms in Quebec, Canada, regarding the self-reported cleaning protocol used for feeding equipment of preweaning calves. During the visit, a visual score was given to the feeding equipment available at the farm. Afterward, ATP luminometry measurements were obtained using Hygiene UltraSnap and MicroSnap swabs (Hygiene, Camarillo, CA), and the liquid rinsing technique for buckets, nipples, bottles, esophageal tube feeders (ET), the tube of automatic milk feeders (AMF), water samples, and milk replacer. An additional direct swabbing technique was performed on buckets and nipples. The fluid retrieved from the liquid rinsing technique was also used to determine the total bacterial count (TBC) and total coliform count. Based on the bacteriological analysis, optimal RLU cutoff values to determine contamination were obtained. The median (interquartile range) luminometer measurements using the UltraSnap and direct technique for buckets and nipples were 2,082 (348-7,410) and 3,462 (462-7,518) RLU, respectively; and, using the liquid technique for bottles, ET, AMF, water, and milk replacer were 43 (4-974), 15 (4-121), 301 (137-1,323), 190 (71-358), and 94 (38-218) RLU, respectively. Overall, for all equipment and both techniques used, higher RLU values were seen in UltraSnap samples compared with MicroSnap samples. Additionally, for buckets and nipples, higher RLU values were obtained for the direct swabbing method compared with the liquid sampling method for both swabs used. No differences in the level of contamination were seen between the different feeding equipment used within a farm. Overall, a higher correlation with bacteriological results was noticed for ATP luminometry compared with the visual score, with a high correlation for nipples and bottles using the UltraSnap and liquid technique. Based on the classification of "contaminated" (TBC ≥100,000 cfu/mL) or "not contaminated" (TBC <100,000 cfu/mL), optimal ATP luminometer cutoff values for buckets, nipples, bottles, AMF, water, and milk replacer were 798, 388, 469, 282, 1,432, and 93 RLU, respectively. No clear association was found between ATP measurements and the self-reported cleaning protocol. This study gave new insights into the current cleaning procedures and contamination of feeding equipment for preweaning calves on dairy farms in Quebec. In addition, ATP luminometry cutoff values could help benchmark farms regarding cleaning practices and provide customized advice, improving the overall hygiene management, and thus the health, of preweaning calves on dairy farms.

Low reticuloruminal pH (rpH), often observed in subacute ruminal acidosis (SARA), may negatively affect rumen health and animal performance. To investigate the variability of rpH and the prevalence of SARA on commercial farms, we conducted an observational study on 110 early-lactation Holstein cows of different parities from 12 farms selected to cover a broad range of farm management strategies. The rpH of each cow was continuously monitored for 50 d using wireless boluses. To study the effects of animal and farm management characteristics on rpH, we used a multivariable mixed model analysis with the animal and farm as random effects. Automatic milking system and presence of corn silage in the ration were associated with a decrease in rpH of 0.37 and 0.20 pH units, respectively, whereas monensin supplementation was associated with an increase of 0.27 pH units. The rpH increased by 0.15 pH units during the first 60 d in milk. We defined a SARA-positive day as rpH below 5.8 (SARA5.8) or 6.0 (SARA6.0) for at least 300 min for 1 d. Using those definitions, during our study, a total of 38 (35%) and 65 (59%) cows experienced at least one episode of SARA5.8 and SARA6.0, respectively. The proportion of cows with at least one SARA-positive day varied among farms from 0 to 100%. Automatic milking system was associated with an increased risk of SARA5.8 (odds ratio: 10) and SARA6.0 (odds ratio: 11). The use of corn silage was associated with an increased risk of SARA5.8 (odds ratio: 21), whereas the use of monensin was associated with a decreased risk of SARA5.8 (odds ratio: 0.02). Our study shows that rpH is quite variable among farms, but also among animals on the same farm. We also show that multiple animal and farm characteristics are associated with rpH variability and the risk of SARA under commercial conditions.

The objective of this cross-sectional study was to standardize a reliable and repeatable swabbing technique using ATP luminometry (light emission proportional to the amount of ATP with result provided in relative light units [RLU]) to describe the cleanliness of various feeding equipment used for preweaning calves in dairy farms. A total of 7 Québec commercial dairy herds were selected conveniently. Following visual hygiene scoring, the cleanliness of every available piece of feeding equipment was assessed using direct surface swabbing for buckets and nipples with Hygiena UltraSnap swabs. A liquid rinsing technique was used for esophageal feeders, bottles, and automatic milk feeders (AMF) with UltraSnap, AquaSnap, and MicroSnap swabs. To validate direct swabbing technique of buckets, a stage within and between operators was realized, as well as a conventional bacterial culture. A total of 519 swab samples were obtained from 201 pieces of equipment. The median (interquartile range) contamination in RLU for a bottle, esophageal feeder, AMF, bucket and nipple was 2 (1;6), 2 (0;12), 52 (19;269), 886 (128;7,230) and 899 (142;6,928), respectively. The direct swabbing technique, which consists in swabbing directly the surface of an equipment, showed excellent correlation for intrarater reliability (intraclass correlation (ICC) = 0.93; 95% CI: 0.88–0.96). The interoperator (2 sessions with 3 different operators) reliability also showed high correlation (ICC = 0.88; 95% CI: 0.78–0.94 for the first session, and ICC = 0.89; 95% CI: 0.79–0.95 for the second session). Luminometer values were positively associated with the visual score of esophageal feeders, AMF and buckets. A positive correlation between bacterial culture and direct swabbing of buckets was also found for the UltraSnap (rs = 0.653; 95% CI: 0.283–0.873; P = 0.0003) and MicroSnap (rs = 0.569, 95% CI: 0.309–0.765; P = 0.002). This study describes a standardized and practical on-farm swabbing technique for assessing the hygienic status of feeding equipment by luminometry, which can be integrated in the investigation of preweaning dairy calves problems.