D. Pellerin

A survey of dairy calf management practices in Canada that affect animal welfare

There is growing interest among the public in farm animal welfare and a need for methods to assess animal welfare on farm. A survey on calf rearing practices that might affect dairy calf welfare was performed via a 1-h interview on 115 dairy farms (mean +/- SD: herd size=52.5+/-20.9 cows; milk production=8,697+/-1,153L) distributed throughout the province of Quebec. Despite frequent recommendations, many dairy producers continue to use management practices that increase the health risks of milk-fed calves. Major risk factors for poor calf welfare identified were 1) no use of calving pen in 51.3% of herds and low level of surveillance of calvings, especially at nighttime (once every 12h), 2) no disinfection of newborns navel in 36.8% of herds, and delayed identification and, hence, calf monitoring (3 d), 3) 15.6% of farms relied on the dam to provide colostrum and none checked colostrum quality or passive transfer of immunity, 4) dehorning and removal of extra teats proceeded at late ages (6.4 wk and 6.7 mo, respectively) and without adequate pain control, 5) use of traditional restrictive milk feeding and waste milk distributed to unweaned calves without precaution in 48.2% of herds, 6) abrupt weaning performed in 16.5% of herds, and 7) calves housed individually in 87.9% of herds, and most inappropriate housing systems (crate=27.0%, tie-stall=13.9%, attached against a wall=5.7%) remained. This risk factor assessment was the first step in an intervention strategy to improve calf welfare on dairy farms.

Prevalence of lameness and associated risk factors in Canadian Holstein-Friesian cows housed in freestall barns

Lameness is a severe welfare problem and a production-limiting disease in dairy farming. The objectives of this study were to determine prevalence of lameness and investigate cow- and herd-level factors associated with lameness in dairy cows housed in freestall barns in 3 Canadian provinces. A purposive sample of 40 Holstein-Friesian cows was selected from each of 141 dairy farms in Québec, Ontario, and Alberta. In total, 5,637 cows were scored once for lameness (presence of limping when walking). Data collected included information on individual cows (hock lesions, claw length, body condition score, parity, days in milk, and milk production), management practices (floor and stall cleaning routine, bedding routine, and footbath practices), and facility design (stall dimensions, stall base and bedding type, width of feed alley, flooring type, and slipperiness) hypothesized to be risk factors for lameness. Multilevel mixed logistic regression models were constructed (including farm as a random effect and province as a fixed effect). Herd-level lameness prevalence ranged from 0 to 69% (mean = 21%). Lameness prevalence increased with increasing parity; compared with first parity, cows in parity 2, 3, and ≥ 4 had 1.6, 3.3, and 4 times, respectively, higher odds of being lame. Furthermore, the odds of lameness were 1.6 times greater in cows with low body condition score (≤ 2.5) than in cows with a higher body condition score. In addition, injured hocks and overgrown claws were associated with 1.4- and 1.7-fold increased odds of being lame, respectively, whereas every 1 kg increase in daily milk production was associated with a 3% decrease in the odds of being lame. Lameness prevalence was higher in herds with ≤ 100 cows, but lower in barns with a sand or dirt stall base, or with bedding ≥ 2 cm deep. Cows exposed to very slippery floors had 2 times the odds of being lame compared with cows exposed to nonslippery floors. We attributed the wide range of lameness prevalence to the great variability in facilities and management practices among farms. Finally, we inferred that the prevalence of lameness could be decreased by improving management of multiparous, thin, or injured cows and by adopting management practices intended to improve cow comfort, namely the floors slip resistance and the stalls lying surface.

Complete-lactation milk and component yields following a short (35-d) or a conventional (60-d) dry period management strategy in commercial Holstein herds

A total of 850 cows distributed among 13 commercial Holstein herds were involved in this study to compare the effects of 2 different dry period (DP) management strategies on milk and component yields as well as body condition score (BCS) over complete lactations. Within each herd and every 2 mo, cows were assigned to a short (35 d dry; SDP) or conventional (60 d dry; CDP) DP management based on previous lactation 305-d milk yield, predicted calving interval, and parity: primiparous (n=414) and multiparous (n=436). Cows assigned to CDP were fed a far-off dry cow ration from dry-off until 21 d prepartum, and were then switched to a precalving ration. Cows assigned to SDP were fed the precalving ration throughout their DP. Rations were different across herds, but the late-lactation, precalving, and early lactation rations were identical for both treatment groups within each herd. Additional milk was obtained at the end of lactation from cows assigned to SDP due to the extended lactation. Average daily milk yield in the following lactation was not different between treatments for third- or greater-lactation cows, but was significantly decreased in second-lactation SDP cows. However, when expressed as energy-corrected milk, this difference was not significant. Although lower for primiparous than multiparous cows, body weight and BCS were not affected by DP management strategy. Milk production and BCS responses to treatments varied among herds. Results from the present study suggest that a short DP management strategy could be more appropriate for todays dairy cows, although not suitable for all cows or all herds.

Incidence of metabolic disorders and reproductive performance following a short (35-d) or conventional (60-d) dry period management in commercial Holstein herds.

A total of 850 Holstein cows from 13 commercial dairy herds were involved in the present study to compare the effects of 2 different dry period (DP) management strategies on health and reproductive parameters. Cows were assigned to either a short (SDP; 35-d) or a conventional (CDP; 60-d) DP management within each herd, based on previous 305-d milk yield, parity (414 primiparous and 436 multiparous), and estimated calving interval. Cows assigned to CDP were fed a dry cow ration from dry-off until 21 d prepartum, and were then switched to a precalving ration. Cows assigned to SDP were fed the precalving ration throughout their DP. Rations were specific to each herd. A significant treatment × parity interaction was found for culling rate. Dry period management did not affect culling rate for second-lactation cows but a significantly higher culling rate occurred in multiparous CDP cows compared with SDP (42.6 vs. 31.6% ± 3.7 for CDP and SDP, respectively). Management used in the DP did not affect incidence of severe ketosis, displaced abomasum, milk fever, and mastitis, although incidence of these metabolic disorders were lower in second-lactation than third- or greater-lactation cows. The incidence of mild ketosis (evaluated by milk ketone concentration) was lower following SDP, probably as a result of better energy balance. On the other hand, the incidence of retained placenta was higher in multiparous cows assigned to SDP, but the reason for this increase remains unclear. Nevertheless, this did not lead to increased incidence of metritis. Moreover, DP management did not influence reproductive measures, including days in milk at first breeding, number of breedings per conception, as well as conception rates at first and second services. Regarding days open, overall, all 13 herds were not significantly affected by treatment, but 1 herd clearly showed opposite results to the 12 others. Our results indicate that a short DP management strategy could facilitate transition from one lactation to the next by decreasing the incidence of mild ketosis, with no major negative effects on other health parameters and reproduction. The variation in results observed among herds suggests that other management practices influence the response observed following a short or conventional DP, emphasizing the need for other field studies.

Effect of amino acid or casein supply on whole-body, splanchnic, and mammary glucose kinetics in lactating dairy cows

This study was conducted to establish how AA supplied in a free form or as protein (casein, CN) affect the whole-body rate of appearance (WB Ra) of glucose, splanchnic and mammary glucose kinetics, and milk lactose secretion in lactating dairy cows. Five Holstein cows fitted with a rumen cannula and permanent indwelling catheters in the abomasum, portal, hepatic, and mesenteric veins, and one mesenteric artery, were used in a Youden square with 4 periods of 14 d each. Cows were fed a hay-based diet providing 100 and 70% of their net energy and metabolizable protein (MP) requirements, respectively. Treatments consisted of abomasal infusions of water (70% of MP requirements: control, Con), free AA (95% of MP requirements: AA1; and 120% of MP requirements: AA2), or CN (95% of MP requirements: CN1). The free AA mixture had the same profile as CN. On d 14 of each period, [6,6-(2)H(2)]glucose (25.8 mmol/h) was infused into a jugular vein, and blood samples (n=8) were taken over 4h from arterial, portal, hepatic, and mammary sources to measure glucose enrichment and concentration. Splanchnic and mammary plasma flows were determined by downstream dilution of para-aminohippurate and with the Fick principle, respectively. The last 6 milkings of each period were weighed and sampled to measure the yields of milk and components. The AA1 and CN1 treatments were not different for any of the measured parameters. Supplying AA linearly increased glucose WB Ra (AA2 vs. Con: +151 mmol/h) and liver net flux (+149 mmol/h). Utilization of glucose from the plasma compartment by the portal-drained viscera and liver and true portal absorption were not affected by AA supply. From these observations, we suggest that the increased WB Ra was due to increased net hepatic production. The AA from the infusion, in excess of that used to cover the increase in milk protein, were converted to glucose with an apparent efficiency close to 100% of maximum theoretical efficiency. Milk and lactose yields increased linearly with infusions of AA, by 14 and 16% with AA2 treatment, respectively. However, mammary glucose uptake was not significantly altered by AA infusions; this suggests that the mammary gland exerts active control on the uptake and utilization of glucose. For all treatments, the sum of true portal glucose absorption and true hepatic glucose production contributed more than 99% of WB Ra in the lactating cow; this would suggest that renal glucose synthesis makes only a small contribution to WB Ra under these conditions.

Lying times of lactating cows on dairy farms with automatic milking systems and the relation to lameness, leg lesions, and body condition score

Lying down and resting are important for optimal cow health, welfare, and production. In comparison with free stall farms with a milking parlor, farms with automated milking systems (AMS) may place less constraint on how long cows can lie down. However, few studies report lying times on AMS farms. The aims of this study were to describe the variation in lying times of dairy cows in AMS farms and to understand how much of the variation in individual lying times is related to cow-level factors, including lameness, the presence of hock and knee lesions, and body condition score (BCS). We visited 36 farms in Canada (Quebec: n = 10; Ontario: n = 10; British Columbia: n = 4; and Alberta: n = 5), and the United States (Michigan: n = 7). Gait scores, presence of hock and knee lesions, and BCS were recorded for 40 Holstein cows from each herd. Parity and days in milk were retrieved from farm records. Lying time was recorded across 4d using accelerometers (n = 1,377). Multivariable analysis was performed. Of scored cows, 15.1% were lame (i.e., obviously limping; 203 of 1,348 cows). Knee lesions were found in 27.1% (340 of 1,256 cows) and hock lesions were found in 30.8% (421 of 1,366 cows) of the animals. Daily lying time varied among cows. Cows spent a median duration of 11.4 h/d lying down (25th-75th percentile = 9.7-12.9 h), with a lying bout frequency of 9.5 bouts/d (25th-75th percentile = 7.5-12 bouts/d) and a median bout duration of 71 min (25th-75th percentile = 58-87 min/bout). Lameness was associated with cows lying down for 0.6 h/d longer in fewer, longer bouts. Increased lying time was also associated with increased parity, later stage of lactation and higher BCS. Older cows (parity ≥ 3) spent about 0.5 h/d more lying down compared with parity 1 cows, and cows with BCS ≥ 3.5 lay down on average 1 h/d longer than cows with BCS ≤ 2.25. Hock lesions were associated with shorter lying times in univariable models, but no associations were found in the multivariable models. We concluded that only a small proportion of the variation between cows in lying time is explained by lameness, leg lesions, and BCS.

An assessment tool to help producers improve cow comfort on their farms

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.

Associations between lying behavior and lameness in Canadian Holstein-Friesian cows housed in freestall barns.

Lying behavior is an important measure of comfort and well-being in dairy cattle, and changes in lying behavior are potential indicators and predictors of lameness. Our objectives were to determine individual and herd-level risk factors associated with measures of lying behavior, and to evaluate whether automated measures of lying behavior can be used to detect lameness. A purposive sample of 40 Holstein cows was selected from each of 141 dairy farms in Alberta, Ontario, and Québec. Lying behavior of 5,135 cows between 10 and 120 d in milk was automatically and continuously recorded using accelerometers over 4 d. Data on factors hypothesized to influence lying behavior were collected, including information on individual cows, management practices, and facility design. Associations between predictor variables and measures of lying behavior were assessed using generalized linear mixed models, including farm and province as random and fixed effects, respectively. Logistic regression models were used to determine whether lying behavior was associated with lameness. At the cow-level, daily lying time increased with increasing days in milk, but this effect interacted with parity; primiparous cows had more frequent but shorter lying bouts in early lactation, changing to mature-cow patterns of lying behavior (fewer and longer lying bouts) in late lactation. In barns with stall curbs >22 cm high, the use of sand or >2 cm of bedding was associated with an increased average daily lying time of 1.44 and 0.06 h/d, respectively. Feed alleys ≥ 350 cm wide or stalls ≥ 114 cm wide were associated with increased daily lying time of 0.39 and 0.33 h/d, respectively, whereas rubber flooring in the feed alley was associated with 0.47 h/d lower average lying time. Lame cows had longer lying times, with fewer, longer, and more variable duration of bouts compared with nonlame cows. In that regard, cows with lying time ≥ 14 h/d, ≤ 5 lying bouts per day, bout duration ≥ 110 min/bout, or standard deviations of bout duration over 4 d ≥ 70 min had 3.7, 1.7, 2.5, and 3.0 higher odds of being lame, respectively. Factors related to comfort of lying and standing surfaces significantly affected lying behavior. Finally, we inferred that automated measures of lying behavior could contribute to lameness detection, especially when interpreted in the context of other factors known to affect lying behavior, including those associated with the individual cow (e.g., parity and stage of lactation) or environment (e.g., stall surface).

Cow- and farm-level risk factors for lameness on dairy farms with automated milking systems.

Lameness is a major concern to animal health and welfare within the dairy industry. Our objectives were to describe the prevalence of lameness in high-producing cows on farms with automated milking systems (AMS) and to identify the main risk factors for lameness at the animal and farm level. We visited 36 AMS farms across Canada and Michigan. Farm-level factors related to stall design, bedding use, flooring, and stocking rates were recorded by trained observers. Cows were scored for lameness, leg injuries, body condition (BCS), and body size (hip width and rump height; n=1,378; 25-40 cows/farm). Mean herd prevalence of clinical lameness was 15% (range=2.5-46%). Stall width relative to cow size and parity was found to be the most important factor associated with lameness. Not fitting the average stall width increased the odds of being lame 3.7 times in primiparous cows. A narrow feed alley [<430cm; odds ratio (OR)=1.9], obstructed lunge space (OR=1.7), a low BCS (OR=2.1 for BCS ≤2.25 compared with BCS 2.75-3.0), and presence of hock lesions (OR=1.6) were also identified as important risk factors for lameness. Only 1 of 36 farms had stalls of adequate width and length for the cows on their farm. For lameness prevention, it can be concluded that more emphasis needs be placed on either building stalls of appropriate width or selecting for smaller-framed cows that fit the existing stalls.

Soil nitrous oxide emissions after deposition of dairy cow excreta in eastern Canada.

Urine and dung deposited by grazing dairy cows are a major source of nitrous oxide (NO), a potent greenhouse gas that contributes to stratospheric ozone depletion. In this study, we quantified the emissions of NO after deposition of dairy cow excreta onto two grassland sites with contrasting soil types in eastern Canada. Our objectives were to determine the impact of excreta type, urine-N rate, time of the year, and soil type on annual NO emissions. Emissions were monitored on sandy loam and clay soils after spring, summer, and fall urine (5 and 10 g N patch) and dung (1.75 kg fresh weight dung) applications to perennial grasses in two successive years. The mean NO emission factor (EF) for urine was 1.09% of applied N in the clay soil and 0.31% in the sandy loam soil, estimates much smaller than the default Intergovernmental Panel on Climate Change (IPCC) default value for total excreta N (2%). Despite variations in urine composition and in climatic conditions, these soil-specific EFs were similar for the two urine-N application rates. The time of the year when urine was applied had no impact on emissions from the sandy loam soil, but greater EFs were observed after summer (1.59%) than spring (1.14%) and fall (0.55%) applications in the clay soil. Dung deposition impact on NO emission was smaller than that of urine, with a mean EF of 0.15% in the sandy loam soil and 0.08% in the clay soil. Our results suggest (i) that the IPCC default EF overestimates NO emissions from grazing cattle excreta in eastern Canada by a factor of 4.3 and (ii) that a region-specific inventory methodology should account for soil type and should use specific EFs for urine and dung.