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.

The use of fatty acid profiles from milk recording samples to predict body weight change of dairy cows in early lactation in commercial dairy farms Franziska Dettmann12, Daniel Warner1, Albert Johannes Buitenhuis3, Morten Kargo34, Anne Mette Hostrup Kjeldsen4, Niels Henning Nielsen5, Daniel M. Lefebvre1, Debora E. Santschi1 1Valacta, Sainte-Anne-de-Bellevue, Canada 2LKV Niedersachsen e.V., Leer, Germany 3Molecular Biology and Genetics, Aarhus University, Tjele, Denmark 4SEGES, Aarhus, Denmark 5RYK, Aarhus, Denmark

The use of adjustment factors with alternate morning (AM) and evening (PM) milk tests to predict daily milk yield and fat percentage from single milking could lead to erroneous daily data. The aims of this study were to evaluate the relationship between predicted daily milk yield or milk fat percentage, calculated using single milking samples and Canadian adjustment factors, and the actual daily milk yield or milk fat percentage, as well as to explore feeding and management variables, that could improve daily predictions. A total of 4277 Holstein cows in 100 dairy herds were enrolled. Separate PM and AM milk samples were collected for each cow using in-line milk meters. Daily milk yield and milk fat percentage predictions were computed from single-milking samples using adjustment factors taking into account milking interval and milking time. Concordance correlation coefficients between actual daily milk yields and daily milk yield predictions from PM (0.970) and AM (0.974) milkings were higher than those between actual daily milk fat percentages and daily milk fat percentage predictions from PM (0.897) and AM (0.917) milkings. There were only slight prediction improvements when days in milk, parity, and some feeding management variables were entered in models aiming to explain residuals.

The objective of this study was to examine the effect of feeding systems [component and total mixed rations (TMR)] and dietary grain sources (barley, commercial concentrate, corn grain, and high-moisture corn) on lactation characteristics and milk composition. A total of 852,242 test-day records, information on animal characteristics, feed composition, and feeding systems from 104,129 Holstein cows in 4,319 herds covering a period of 5 yr were obtained from Quebec's Dairy Herd Improvement Association (Valacta). We performed descriptive statistics and graphical representations of the data for each type of feeding system and grain source by parity (1 to 3). The milk records were binned in 15-d in milk blocks. Mixed models using a combination of forward and backward stepwise selections were developed to predict milk and milk component yields. The TMR-fed cows had greater yield of milk, fat, protein, and lactose and lower milk urea N (MUN) concentration than component-fed cows at all parities. Cows fed a TMR had higher peak milk yields and greater persistency after peak lactation compared with component-fed cows. In addition, greater yields of milk fat and protein from peak to mid-lactation were found in TMR-versus component-fed cows. In general, greater milk fat and protein yields as well as lower MUN concentration were observed in cows fed corn grain or high-moisture corn compared with barley or commercial concentrate, but parity influenced these relationships. The feeding system by day in milk blocks interaction was significant in models of milk and components yields for all parities, but only for second-lactation cows for MUN concentration. This means that effect of TMR and component feeding differs with stage of lactation. In conclusion, feeding TMR and corn-based diets are associated with greater yield of milk and milk components under commercial conditions.

A retrospective cohort study was conducted using production and health records from Quebec dairy herds which were integrated with the objectives of calculating different lifetime profitability measures and developing analyses of the impact of selected reproduction and health variables on profitability. The dataset for the study consisted of lifetime records for a total of 13 668 Holstein cows from 113 herds and in cohorts of cows calving for the first time between 2000 and 2009. To calculate profit, all the revenues and costs were accumulated on a lifetime basis, and cumulative lifetime profit and cumulative lifetime profit adjusted for the opportunity cost of postponed replacement were selected for analysis. There were statistically significant effects in both profit measures because of age at first calving, cumulative number of days in milk, and cumulative number of days dry as well as the number of health events accumulated by animal lifetime (clinical mastitis, reproductive problems, and feet and legs problems). The results of lifetime profit measures and management variables with an effect on profit results could help dairy producers in the process of monitoring and making decisions regarding profit goals and herd life of their cows.

This study was undertaken to evaluate the relationship between plasma and milk concentrations of vitamin B12 as well as the relationship between plasma or milk concentrations of vitamin B12 and plasma concentration of free fatty acids (FFA) or blood concentration of β-hydroxybutyrate (BHB) of early lactating Ayrshire (AY) and Holstein (HO) cows. A total of 44 dairy herds (7 AY and 37 HO herds) and 62 AY (21 in first, 19 in second, and 22 in third and more lactations) and 228 HO (51 in first, 74 in second, and 103 in third and more lactation) cows between 3 and 40 d in milk were involved in the study. Hand-stripped milk samples and blood samples were taken 6 h after the morning milking. Milk and plasma samples were analyzed for vitamin B12 concentration and plasma samples were analyzed for FFA concentration. A handheld device was used for blood BHB concentration determination. Thresholds for elevated plasma FFA concentration and hyperketonemia were set at ≥0.70 and ≥1.2 mmol/L, respectively. Vitamin B12 concentration in milk of AY primiparous cows [2,557 (1,995-3,276) pg/mL] was lower than in milk from HO primiparous cows [3,876 (3,356-4,478) pg/mL], whereas no difference was observed among other parities and breeds. Regardless of breeds, plasma concentration of vitamin B12 of first and second parities was lower than plasma concentration of third and more lactation cows. Milk vitamin B12 concentration was positively correlated with plasma vitamin B12 concentration, but the relationship was stronger for AY (ρ averaging 0.63) than for HO cows (ρ averaging 0.36). For AY and HO breeds, a significant relationship between milk or plasma vitamin B12 concentrations and plasma FFA concentration (ρ between 0.29 and 0.59) was observed. Moreover, cows with elevated plasma FFA concentration had greater milk and plasma vitamin B12 concentrations than cows with normal plasma FFA concentration. No relationship between vitamin B12 concentration in milk or plasma and blood BHB concentration and hyperketonemia was noted. In summary, milk is not well correlated with plasma vitamin B12 concentration for HO. It could be hypothesized that elevated plasma concentration of FFA could have a negative effect on the use of vitamin B12 by cow cells, which increases the concentration of the vitamin in plasma and its secretion in milk.

The purpose was to describe the prevalence and effect of elevated milk β-hydroxybutyrate (BHB) as detected by routine Fourier-transform infrared analysis in Dairy Herd Improvement milk samples. Data collected over 4 yr included cow information as well as milk yield and composition from 498,310 samples from postparturient Holstein cows (5-35d in milk) from 4,242 herds. The following thresholds were used to classify cows based on their early lactation milk BHB concentration: <0.15mmol/L=negative; 0.15 to 0.19mmol/L=suspect; and ≥0.20mmol/L=positive. Overall prevalence (suspect + positive) was 22.6% and was higher for older cows (18.7, 19.5, and 27.6%, for cows in their first, second, and third or greater lactation, respectively). Distribution with regards to days in milk was different among parity groups, with first-lactation cows having highest prevalence (30%) in the first week after calving; cows in their second and third and greater parity had the highest prevalence in the second week after calving, at 25.8 and 34.6%, respectively. Season of calving affected the prevalence of elevated milk BHB, with cows calving in the fall and spring seasons showing higher prevalence. Distribution among herds was highly variable, as 45% of herds had a prevalence of 20% or less, 47% of herds had a prevalence between 21 and 40%, 6% of herds had a prevalence between 40 and 50%, and 2% of herds had a prevalence of 50% or above. Positive cows had lower milk yield, protein concentration and yield, and lower Transition Cow Index than negative cows, but also higher fat concentration and yield, as well as higher somatic cell count than negative cows. Suspect cows were generally intermediate. The present analysis highlights the opportunity for elevated milk BHB monitoring at the herd level through routine BHB testing in Dairy Herd Improvement milk samples.

Hyperketonemia (or ketosis) is one of the most frequent diseases in dairy cattle. As clinical ketosis is not widely recorded, the level of milk β-hydroxybutyrate is used as its indicator. Milk fatty acid profile is considered to be related to the energy balance of cows in early lactation. The objective of this study was, therefore, to investigate the genetic associations between milk β-hydroxybutyrate and milk fatty acids in early first lactation of Canadian Holstein cows. Test-day data were available on milk β-hydroxybutyrate and five fatty acid groups: short-chain (C4–C10), medium-chain (C12–C16), long-chain (C17–C22), saturated (no double bond) and unsaturated (one or more double bonds). Only the first cow's test-day record between 5 and 40 DIM was considered for all traits, because most of the metabolic changes occur over this time period. The data set consisted of 23,345 cow records from 1541 sires and 2510 herds. Data were analyzed with a 6-variate linear sire model using the Average Information-Restricted Maximum Likelihood (AI-REML) procedure in the DMU package. Heritability of 0.13 was found for milk β-hydroxybutyrate. Heritability estimates for fatty acids ranged from 0.10 to 0.29. Genetic correlations between milk β-hydroxybutyrate and short chain, medium chain and saturated fatty acids were low and not significantly different from zero. Genetic correlations between milk β-hydroxybutyrate and long chain and unsaturated fatty acids were 0.51 and 0.48, respectively. These results confirm the known relationship between milk β-hydroxybutyrate and energy balance status in early lactation, explained by the release of long chain fatty acids from the mobilization of body fat reserves.

Hyperketonemia is a common early lactation disorder. Analysis of β-hydroxybutyrate (BHBA) by Fourier transform infrared spectroscopy in DHI milk samples provides a rapid and low-cost herd-level monitoring tool to evaluate the prevalence of hyperketonemia. The objective of this study was to evaluate the impact of elevated BHBA concentrations in early lactation DHI samples on reproduction and 305-d milk and component yields. Test-day and lactation records from 220,939 Holstein cows (114,267 primiparous and 106,672 multiparous) were used. All cows in the dataset had BHBA concentration on first test-day between 5 and 35 DIM. The following thresholds were used to classify cows based on milk BHBA concentration in early lactation: < 0.15 mmol/L = Negative (NEG); 0.15 to 0.19 mmol/L = Suspect (SUSP); and ≥ 0.20 mmol/L = Positive (POS), based on a previously published trial comparing milk and blood BHB concentrations. The MIXED procedure of SAS was used to evaluate the impact of BHBA classification on reproduction and production outcome. Cows with high BHBA concentration in early lactation had longer calving to first service and first service to conception intervals, increased days open, more services per conception, and lower 56d non-return rate. Cows with high BHBA concentration in early lactation produced higher 305-d milk and fat yields, but lower 305-d protein yields. Overall, trends were similar for primiparous and multiparous cows. Results indicate that hyperketonemia negatively impacts reproduction, but suggest higher producing cows are more affected. Monitoring and prevention strategies to reduce the prevalence of hyperketonemia in early lactation could result in improved reproduction and potential benefits on lactation milk yield.

Alternate a.m.-p.m. milk testing has been introduced in many countries and is often used instead of collecting milk for 2 consecutive milkings. Models taking into account milking interval have been developed to predict 24-h yield and concentration from milk yield and fat concentration single-milking values. However, there is still a gap between the prediction and the reality. It has been hypothesized that feeding factors could help better estimating 24-h prediction. The purpose of this study was to evaluate feed-related management factors affecting a.m. and p.m. milk yield and milk fat, protein, lactose, urea, somatic cell count (SCC), and β-hydroxybutyrate (BHBA) concentrations as a single predictor of 24-h concentrations. Separate milk samples from a.m. and p.m. milkings were taken for each cow on 98 tiestall and 2 freestall barns. Milk samples were analyzed using Fourier transform infrared spectroscopy. Milk production weighted averages were calculated to obtain daily concentrations. Milking intervals, number of concentrate meals offered, feeding systems (conventional, individual concentrate feeding [ICF] and total mixed ration [TMR]), interval between milking and last concentrate meal were recorded and used as independent variables in the multiple regression analysis. Milk yield and component concentrations from a.m. or p.m. samples to calculated daily concentrations ratios were computed and considered as dependant variables. For analysis purposes, individual ratios were averaged by herd. Multiple regressions were performed with Proc GLMSELECT of SAS using stepwise selection and P = 0.05 as the cut-off point. Highest R-squares were obtained while predicting milk yield (a.m.: r2 = 0.63; p.m.: r2 = 0.51), followed by fat concentration (a.m.: r2 = 0.30; p.m.: r2 = 0.26), SCC (a.m.: r2 = 0.29; p.m.: r2 = 0.26), BHBA (a.m.: r2 = 0.15; p.m.: r2 = 0.16), protein (a.m.: r2 = 0.14; p.m.: r2 = 0.10), urea (a.m.: r2 = 0.13; p.m.: r2 = 0.08), and lactose (a.m.: r2 = 0.03; p.m.: r2 = 0.00). Milking interval affected daily prediction of a.m. and p.m. milk yield and a.m. and p.m. fat, SCC, and BHBA contents. Interval between milking and last concentrate meal affected 24-h prediction in all a.m. models except for BHBA. Feeding system had an impact on 24-h prediction of a.m. and p.m. protein and urea concentrations. Regarding lactose, results confirm that a.m. or p.m. concentrations without adjustment could predict 24-h lactose concentration as this component is relatively constant. In summary, feed-related management factors slightly improved 24-h prediction as compared with models adjusting only for milking interval as suggested by the low R-Square increment.

Effective management and an appropriate environment are essential for dairy cattle health and welfare. Codes of practice provide dairy producers with best practice guidance for the care and handling of their cattle. New Canadian recommendations have been established for the dairy industry. The objectives of this study were to develop an on-farm assessment tool that helps producers assess how well they are meeting their code of practice and that identifies management and environment modifications that could improve dairy cow comfort on their farms. The assessment tool addressed critical areas of dairy cow comfort, including accommodation and housing (stall design, space allowance, stall management, pen management, milking parlor, and transfer alleys), feed and water (body condition scoring, nutrition), and health and welfare (lameness, claw health, and hoof-trimming). Targets of good practices were identified from the requirements and recommendations of the code of practice. Each farm received a score for each target, ranging from 0 (target not reached) to 100 (target reached). One hundred tiestall and 110 freestall farms were surveyed in 3 provinces of Canada (Quebec, Ontario, and Alberta). The duration of the assessment, in 2 visits lasting, on average, 8 and 9h (range between freestall and tiestall farms) and 4 and 4.1h, was beyond the targeted 3 to 4h due mainly to the animal-based measures; strategies to reduce the duration of the assessment were discussed. Standard operating procedures were developed to ensure consistency in measuring and recording data. Periodical checks were conducted by trainers to ensure all 15 assessors remained above target agreement of weighted kappa ≥0.6. Average scores for all critical areas ranged from 25 to 89% for freestall farms and from 48 to 95% for tiestall farms. These scores need to be considered with caution when comparing farms because scores could not always be calculated the same way between housing systems. An evaluation report was provided and discussed with each producer, identifying strengths and areas for improvement that could benefit dairy cow comfort on their farms. The producers were convinced of the effectiveness of our tool for assessing cow comfort (freestall: 86%; tiestall: 95%) and in assisting them to make decisions for improvements (freestall: 83%; tiestall: 93%). Our cow comfort assessment tool served as background material for the Dairy Farmers of Canada animal care assessment program.

In Québec first calving occurs on average at 27 mo, whereas the target is 23 to 24.5 mo to maximize herd profitability. The aim of this study was to quantify current and future heifer growth using individual heifer random regressions and to generate indicators (such as heifer weight and height at 15 and 24 mo, average daily gain before and after 15 mo, age at which optimal weight for breeding is attained, i.e., 55% of mature weight, and reliability of the 15- and 24-mo weight predictions) that could be used as a practical on-farm tool. Dairy heifer weight estimated by heart girth circumference and height measured at the withers (from 0 to 27 mo) were obtained from the Valacta database (DHI agency, Ste-Anne-de-Bellevue, QC, Canada) from 1995 to 2012. Indicators were calculated based on the current situation of Holstein (HO), Ayrshire (AY), Jersey (JE), and Brown Swiss (BS) heifer growth in Québec. Heifers with less than 2 records were excluded from the analysis. Mature weights were determined by weight at calving of cows from third or greater lactation for a given breed and were 710 kg for HO, 625 kg for AY, 470 kg for JE, and 670 kg for BS. Estimated weights at 15 and 24 mo were 425 and 627, 334 and 482, 297 and 429, and 379 and 560 kg for HO, AY, JE, and BS, respectively, which are heavy enough for breeding and calving, except for AY. Relative reliabilities of the 15- and 24-mo weight predictions were on average 89 and 60%, respectively, based on measurements up to 15 mo. For HO, AY, JE, and BS, wither heights at 15 and 24 mo were 134 and 143, 125 and 134, 122 and 131, and 130 and 140 cm, respectively. Age at optimal breeding weight was 13.6, 15.5, 12.6, and 14.5 mo for HO, AY, JE, and BS, respectively. These data suggest that it is realistic to expect a first calving at 24 mo for HO, JE, and BS. A growth delay was observed for AY; average daily gain was 655 and 538 g/d before and after 15 mo, respectively. The average daily gain before and after 15 mo was 848 and 747 g/d for HO, 603 and 486 g/d for JE, and 775 and 662 g/d for BS, respectively. These indicators could be calculated for an individual heifer and on a herd-level basis and used on farm as a management tool for reducing age at first breeding and at first calving.

The objectives of this study were to: 1) quantify culling rates of Quebec dairy herds, and 2) investigate if Quebec dairy farms could be differentiated based on herd-level factors such as management, reproduction, production and health indices, and explore their relationship with herd culling rate.