Factors associated with dairy calf health in automated feeding systems in the Upper Midwest United States

Automated calf feeding systems are becoming more common on US dairy farms. The objective of this study was to evaluate calf health in these systems and to identify risk factors associated with adverse health outcomes on farms in the Upper Midwest United States. Over an 18-mo period on bimonthly farm visits to 38 farms, calves (n = 10,179) were scored for attitude, ear, eye, and nasal health, as well as evidence of diarrhea (hide dirtiness score of perianal region, underside of the tail, and tailhead). For all health score categories, a score of 0 represented an apparently healthy animal. Rectal temperatures were taken in calves scoring a ≥2 in any category, and those with a temperature >39.4°C were categorized as having a fever (n = 550). Associations were determined between farm-level variables and health scores to identify risk factors for higher (worse) scores. All health outcomes were associated with season of measurement, with fall and winter seasons increasing the odds of a high health score or detected fever. High bacterial counts measured in the milk or milk replacer were associated with increased odds for higher attitude and ear scores, and higher odds for calves having a detected fever. Higher peak milk allowance (L/d) was associated with lower hide dirtiness score, whereas a longer period of time (d) to reach peak milk allowance was associated with increased odds of higher scores for attitude, ear, eye, and hide dirtiness, as well as fever. Higher fat content in milk was associated with increased odds of high eye score. Less space per calf (m²/calf) was associated with higher ear and eye scores, whereas larger group sizes were associated with increased odds of higher nasal score and decreased odds of higher hide dirtiness score. Rectangular pen shape was associated with decreased odds of higher eye score. Absence of a positive pressure ventilation tube was associated with increased odds of having a calf detected with a fever. Based on these results, we hypothesize that these factors could be managed to improve health outcomes for dairy calves on automated feeding systems.     

Feeding behavior of calves fed small or large amounts of milk

Little is known about feeding behavior in group-housed calves fed with an automated feeding system. To examine the influence of milk feeding level on feeding behavior in such a system, we fed calves either 4 L of milk replacer per d (LIM) or allowed ad libitum (AL) intake (n = 25 per treatment). In a second experiment another set of calves was fed 4 L (low milk volume, LM) or 12 L (high milk volume, HM) of whole milk (n = 14 per treatment). Results were analyzed separately using a mixed model including calf, treatment, and time as factors, and feeding behavior as variables. Milk intake by AL or HM calves increased during the first 2 wk, reaching a maximum intake that reached a plateau during the next 4 wk. Concentrate intake was negligible during the first 14 d, with LIM and LM calves increasing their consumption from d 22. Concentrate intake by AL and HM calves remained low until weaning in experiment 1 and the end of trial in experiment 2 (d 43 for both). The frequency of visits was higher in LIM and LM calves than in AL and HM calves during the first 42 d, with most visits being unrewarded (∼90%). This resulted in higher occupancy time of the feeder by LIM and LM calves. During weaning in experiment 1 (d 44 to 48), there was no difference in occupancy time between treatments. Calves in the AL and HM groups distributed their visits throughout the day, whereas LIM and LM calves made most visits just before the time when the next allowance of milk became available. In experiment 1, AL calves showed a greater weight gain during the first 21 d but LIM calves had greater gains between d 22 and 50. However, the overall average daily weight gain was higher for AL calves. In experiment 2, HM calves had a greater gain than LM calves for the first 4 wk of trial but there was no difference between treatments during the last 2 wk. There were no differences between treatments in the incidence of disease in either experiment. The duration of time spent lying down in experiment 2 was higher for HM calves but only when they were older (4 to 5 wk). No differences were found between treatments at 2 wk of age. In conclusion, feeding high levels of milk or replacer improved weight gain and reduced unrewarded visits to the milk feeder, improving the efficiency of use of the milk feeders. However, it reduced concentrate intake and the advantages were less obvious after 3 wk of age. No increased incidence of disease was found for high-fed calves (AL and HM groups). Lying time was also higher for high-fed calves but only at an older age (4 to 5 wk).     

Mortality and health treatment rates of dairy calves in automated milk feeding systems in the Upper Midwest of the United States

Automated calf feeding systems are increasing in use across the United States, yet information regarding health and mortality outcomes of animals in these systems is limited. The objective of this study was to investigate the relationship between farm management practices, housing, and environmental factors with mortality and health treatment rates of preweaned dairy calves housed in groups with automated feeding systems. Farm records were collected for health treatments and mortality on 26 farms in the Upper Midwest of the United States. Relationships between factors of interest and mortality or treatment rate were calculated using a correlation analysis. Overall median annual mortality rate was 2.6 (interquartile range = 3.6; range = 0.24–13.4%), and 57% of farms reported mortality rates below 3%/yr. Farms that disinfected the navels of newborn calves had lower mortality rate (mean = 3.0%; standard error = 0.8; 78% of farms) than farms that did not disinfect (mean = 7.3%; standard error = 1.6; 22% of farms). Farm size (number of cows on site) was negatively associated [correlation coefficient (r) = ?0.53], whereas the age range in calf groups was positively associated (r = 0.58) with mortality rate. Average serum total protein concentration tended to be negatively associated with annual mortality rate (r = ?0.39; median = 5.4; range = 5.0–6.4 g/dL). Health treatment rate was positively associated with coliform bacterial count in feeder tube milk samples [r = 0.45; mean ± standard deviation (SD) = 6.45 ± 4.50 ln(cfu/mL)] and the age of calves at grouping (r = 0.50; mean ± SD = 5.1 ± 3.6 d). A positive trend was detected for coliform bacterial count of feeder mixing tank milk samples [r = 0.37; mean ± SD = 3.2 ± 6.4 ln(cfu/mL)] and calf age at weaning (r = 0.37, mean ± SD = 57.4 ± 9.6 d). Seasonal patterns indicated that winter was the season of highest treatment rate. Taken together, these results indicate that, although automated feeding systems can achieve mortality rates below the US average, improvements are needed in fundamental calf care practices, such as colostrum management and preventing bacterial contamination of the liquid diet and the calf environment.     

Predicting morbidity and mortality using automated milk feeders: A scoping review

Automated milk feeders (AMF) are computerized systems that provide producers with a tool that can be used to more efficiently raise dairy calves and allow for easier implementation of a high plane of nutrition during the milk feeding phase. Automated milk feeders also have the ability to track individualized behavioral data, such as milk consumption, drinking speed, and the number of rewarded and unrewarded visits to the feeder, that could potentially be used to predict disease development. The objective of this scoping review was to characterize the body of literature investigating the use of AMF data to predict morbidity and mortality in dairy calves during the preweaning stage. This review lists the parameters that have been examined for associations with disease in calves and identify discrepancies found in the literature. Five databases and relevant conference proceedings were searched. Eligible studies focused on the use of behavioral parameters measured by AMF to predict morbidity or mortality in preweaned dairy calves. Two reviewers independently screened titles and abstracts from 6,675 records identified during the literature search. After title and abstract screening, 382 studies were included and then assessed at the full-text level. Of these, 56 studies fed calves using an AMF and provided some measure of morbidity or mortality. Thirteen examined AMF parameters for associations with morbidity or mortality. The studies were completed in North America (n = 6), Europe (n = 6), and New Zealand (n = 1). The studies varied in sample size, ranging from 30 to 1,052 calves with a median of 100 calves. All 13 studies included enteric disease as an outcome and 11 studies evaluated respiratory disease. Of the studies measuring enteric disease, 8 provided disease definitions (n = 8/13, 61.2%); however, for respiratory disease, only 5 provided a disease definition (n = 5/11, 45.5%). Disease definitions and thresholds varied greatly between studies, with 10 using some form of health scoring. When evaluating feeding metrics as indicators of disease, all 13 studies investigated milk consumption and 6 and 7 studies investigated drinking speed and number of rewarded and unrewarded visits, respectively. Overall, this scoping review identified that daily milk consumption, drinking speed, and rewarded and unrewarded visits may provide insight into early disease detection in preweaned dairy calves. However, the disparity in reporting of study designs and results between included studies made comparisons challenging. In addition, to aid with the interpretation of studies, standardized disease outcomes should be used to improve the utility of this primary research.     

Behavioral changes in group-housed dairy calves infected with Mannheimia haemolytica

Monitoring sickness behavior may improve identification, management, and welfare of sick animals. The objective of this study was to characterize components of sickness behavior in group-housed dairy calves, using an experimental disease challenge model with Mannheimia haemolytica (MH). Holstein bull calves (aged 3–7 weeks; 58.0 ± 12.0 kg of body weight) were group-housed based on age and body weight in sand-bedded pens (6 calves/pen, 6.6 m²/calf) and provided pasteurized waste milk (8 L/d) 2×/d and grain concentrate ad libitum. Within group, calves were randomly assigned to 1 of 2 treatments: (1) inoculation at the tracheal bifurcation with 3 × 10⁹ cfu of MH suspended in 5 mL of sterile phosphate buffered saline (PBS) followed by a 120 mL wash PBS (MH; n = 12, 3/pen), or (2) inoculation with 5 mL + 120 mL of sterile PBS only (control; n = 12, 3/pen). Rectal temperature and health scores were collected from d 0 to +6 of the challenge. A range of behaviors, including feeding patterns and social interactions, were recorded from video from d 0 to +2. The challenge model resulted in calves experiencing a mild disease state: rectal temperatures of MH calves were elevated throughout the challenge compared with control calves, peaking at 12 h postinoculation (39.2 vs. 38.9°C; standard error = 0.14). Many behavioral responses were subject to treatment by day effects, with calves generally becoming less active following inoculation with MH and then returning to baseline. Affected behaviors surrounding feeding included milk feeding time, frequency of competitive displacements, and concentrate feeding time. Lying time was similarly subject to treatment by day effects, and MH calves also spent more time lying on their left side compared with their right (604 vs. 471 min/h; standard error = 32), whereas control calves expressed no laterality. Duration of social lying did not differ, but frequency of social lying bouts decreased in MH calves following inoculation (0.44 vs. 0.75 bouts/h; standard error = 0.04). Social grooming was initiated less by MH calves (0.78 vs. 1.96 min/h; standard error = 0.38), but they tended to receive more social grooming for a greater duration of time (1.59 vs. 1.25 min/h; standard error = 0.13). Overall, we found that infected calves exhibited reduced grooming, feeding, and social interactions, suggesting that these behavioral changes may be useful indicators of early stages of respiratory disease.     

Automated measurement of changes in feeding behavior of milk-fed calves associated with illness

There is a need for improved methods of detecting illness among group-housed milk-fed calves. In 4 separate experiments, we examined whether illness in group-housed dairy calves fed with an automated milk feeder changed their feeding behavior, and whether these changes were affected by low (n = 26) or high (n = 38) milk rations. All calves were subjected to regular health checks that included general condition, rectal temperature, lung auscultation, and fecal scoring. We match paired calves that succumbed to illness with healthy calves on the same feeding allowance. In the days following clinically identified illness (gastroenteric or respiratory affections), sick calves fed high allowances of milk or milk replacer decreased milk intake (−2.59 ± 0.7 L/d) and frequency of visits to the milk feeder (−2.43 ± 0.3 visits/d), and increased the duration of each visit to the milk feeder (1.66 ± 0.5 min/visit) compared with healthy calves fed at the same allowance. However, sick calves fed a low allowance of milk or milk replacer only decreased the duration of each visit to the milk feeder (−1.35 ± 0.2 min/visit) compared with healthy calves. Feed allowance affected feeding behavior associated with illness of milk fed calves.     

Housing and management characteristics of calf automated feeding systems in the Upper Midwest of the United States

Automated milk feeders are used by dairy producers to manage preweaned calves in group housing, but little is known about how these feeding systems are being used in the United States. To better understand how US dairy producers are operating these systems, this study investigated characteristics of barn design, environment, and management practices on 38 farms in the Upper Midwest of the United States via a questionnaire and on-farm measurements. Farms using automated feeders ranged in size from 7 to 300 calves on site. Natural ventilation was used on 50% of the farms, followed by barns with mechanical ventilation (39.5%), tunnel ventilation (7.9%), or outdoor facilities (sheltered plastic domes; 2.6%). Calves were kept in groups of 17.6 ± 9.8 animals (range: 5.9 to 60.5) with an average space allowance of 4.6 ± 2.0 m²/animal (range: 1.6 to 11.9). Calves on these farms received 3.7 ± 0.75 L (range: 2 to 6) of colostrum, but 22% of the tested calves had serum total protein values lower than 5.0 g/dL. Calves had an initial daily allowance of 5.4 ± 2.1 L (range: 3 to 15 L) of milk or milk replacer, rising to a peak amount of 8.3 ± 2.0 L (range: 5 to 15 L) over 18 ± 11.4 d (range: 0 to 44 d). Milk replacer was fed to calves on 68.4% of the farms compared with whole milk supplemented with nutrient balancer on 23.7% and whole milk alone on 7.9% of the farms. Calves were completely weaned at 56.8 ± 9.0 d of age (range: 40 to 85.5) and 52.1 ± 7.5 d (range: 40 to 79) since introduction into the group pen with the feeder. Notably, bacterial contamination of milk was common; the median coliform count was 10,430 cfu/mL (interquartile range: 233,111; range: 45 to 28,517,000) and standard plate count was 2,566,867 cfu/mL (interquartile range: 15,860,194; range 6,668 to 82,825,000) for samples collected from the feeder tube end (or feeder hose). Some areas of deficiency might be of concern as they might be influencing the success of using automated calf feeding systems. In particular, a better understanding of the dynamics of pathogen load is needed in both the group pen area and in the automated feeder unit itself, as these reservoirs represent significant risk to calf health and welfare.     

Short communication: Identification of diseased calves by use of data from automatic milk feeders

Housing calves in large groups is associated with a higher risk of respiratory disease and with increased difficulties in identifying diseased animals compared with single housing. The aim of the present study was to investigate the effect of clinical disease on some behaviors recorded by automatic milk feeders in pre-weaned dairy calves. The experiment included 27 calves from a Danish research farm and 41 calves from a Swedish research farm. The calves were fed restrictively from a computer-controlled milk feeder, and all calves were subjected to daily clinical examinations for 3 to 26 d, with information gathered on general condition, nasal discharge, lung auscultation findings, coughing, signs of dehydration, naval status, rectal temperature, fecal consistency, and presence of chin abscess, arthritis, umbilical hernia, poor body condition, and poor hair coat. Calves suffering from diarrhea, respiratory disease, fever, or unspecific decreased general condition for more than 2 d were considered to be diseased and were declared to have recovered when they had been free of clinical signs of the disease for at least 2 d. The effects of clinical status (healthy, diseased) on the number of rewarded and unrewarded visits to the calf feeder and drinking rate, respectively, were analyzed by variance component analysis using a mixed model. Milk consumption on diseased and nondiseased days within calves was compared using a Wilcoxon signed rank test. In total, 53 of the calves were diagnosed as diseased during the study period. All cases of diseases were mild and were associated with an unaffected or only mildly affected general condition. Diarrhea was diagnosed in 51 calves, 6 of which also had respiratory disease. In 2 calves, respiratory disease was the only diagnosis. Eleven calves had an unspecific decreased general condition. The number of unrewarded visits was significantly reduced when calves were diseased. In Swedish calves, there was also a tendency for rewarded visits to be reduced during diseased days. Drinking rate and number of rewarded visits increased with increasing age. No effect of clinical status on milk consumption was detected. The number of unrewarded visits was the most sensitive of the 4 feeding behaviors monitored to indicate clinical disease in calves fed restricted milk volumes.     

Factors associated with productivity on automatic milking system dairy farms in the Upper Midwest United States

The objective of this study was to identify housing and management factors associated with productivity on automatic milking system (AMS) dairy farms measured as daily milk yield/AMS and daily milk yield/cow. Management, housing, and lameness prevalence data were collected from 33 AMS farms in Minnesota and Wisconsin during a farm visit. All farms in the study used free-flow cow traffic. Mixed model analysis of cross-sectional data showed that farms with automatic feed push-up via a robot produced more milk per AMS/day and per cow/day than farms where feed was pushed up manually. New versus retrofitted facility, freestall surface, manure removal system, and the number of AMS units/pen were not associated with daily milk yield per AMS or per cow. Cow comfort index (calculated as number of cows lying down in stalls divided by total number of cows touching a stall) was positively associated with daily milk yield/cow. Prevalence of lameness and severe lameness, number of cows per full-time employee, depth of the area in front of the AMS milking station, and length of the exit lane from the AMS milking station were not associated with daily milk yield per AMS or per cow. Multivariable mixed model analysis of longitudinal AMS software data collected daily over approximately an 18-mo period from 32 of the farms found a positive association between daily milk yield/AMS and average age of the cows, cow milking frequency, cow milking speed, number of cows/AMS, and daily amount of concentrate feed offered/cow in the AMS. Factors negatively associated with daily milk yield/AMS were number of failed and refused cow visits to the AMS, treatment time (the time spent preparing the udder before milking and applying a teat disinfectant after milking), and amount of residual concentrate feed/cow. Similar results were also found for daily milk yield on a per cow basis; however, as it would be expected, average days in milk of the herd were also negatively associated with daily milk yield/cow. These findings indicate that several management and cow factors must be managed well to optimize AMS productivity.     

The association between daily average feeding behaviors and morbidity in automatically fed group-housed preweaned dairy calves

Group housing and computerized feeding of preweaned dairy calves is gaining popularity among dairy producers worldwide, yet disease incidence and detection remain a challenge in these systems. The aim of this prospective observational cohort study was to describe the relationship between morbidity and feeding behavior around the period of illness detection. Calves were enrolled upon entrance to the group pen on 10 farms in Minnesota (n = 4) and Virginia (n = 6) utilizing group housing and computerized feeding from February until October 2014. Morbidity and mortality events were recorded by the calf caregiver. Farms were visited either every week (Minnesota) or every other week (Virginia) to collect calf enrollment data, feeding behavior data, and health records. Daily average feeding behaviors (drinking speed, mL/min; daily consumption, L/d; rewarded visits to the feeder; and unrewarded visits to the feeder) were described both overall and for sick and healthy calf days. Multivariable mixed models were built to assess the differences in daily average feeding behaviors (drinking speed, daily consumption, rewarded visits, unrewarded visits) between matched sick and healthy calves around the time of an illness event (?10 to 10 d). Final models were controlled for calf age, region (Minnesota and Virginia), group size, disease diagnosis, the random effect of farm, and repeated measurements on calf. A stratified analysis was performed by both day from treatment event and disease diagnosis. We enrolled 1,052 calves representing 43,607 calf days over 9 mo. From these, 176 sick calves had a matched control and were carried forward to the matched pair analysis. Fifty-five percent of sick calves (97/176) were treated for diarrhea, 30% (53/176) were treated for pneumonia, and 15% (26/176) were treated for ill thrift. Sick calves drank 183 ± 27 mL/min (mean ± standard error) more slowly, drank 1.2 ± 0.6 L/d less, and had 3.1 ± 0.7 fewer unrewarded visits than control calves on the first day of treatment. These differences began up to 4 d before the calf was detected as sick, and persisted for 7 to 10 d after treatment. However, changes in feeding behaviors varied by disease diagnosed. Rewarded visits were not associated with morbidity status. The results of this study indicate that sick calves change their feeding behavior before and during an illness event, suggesting that feeding behavior may be a useful tool to detect disease onset.     

Evaluating effects of providing hay on behavioral development and performance of group-housed dairy calves

Providing access to forage has been shown to influence feeding behavior and non-nutritive oral behavior in individually housed calves, and these effects may be enhanced or altered in calves reared in social housing. We evaluated the effect of hay provision on the behavioral development and performance of group-housed dairy calves. Holstein calves (n = 32) were group-housed (4 calves per group) at 17 ± 3 (mean ± SD) d of age. All calves were provided milk replacer (8 L/d) via an automated milk feeder and pelleted starter and water ad libitum. Pens were randomly assigned to receive either chopped coastal Bermuda grass in buckets adjacent to the starter trough (starter and hay, STH; n = 4 pens), or no additional feed (starter only, ST; n = 4 pens). Calves were weaned through a 10-d stepdown program beginning at 46 d of age. Intake of solid feed and hay were recorded daily, and body weights were measured weekly. The behavior of 2 focal calves per pen was recorded continuously from video for 12 h on 2 consecutive days during each of wk 4, 6, and 7 of life, to measure solid feed intake time, grooming, and pen-directed sucking. Hay provision influenced total feed intake, with calves provided hay having greater total solid feed intake in the week before weaning (0.79 vs. 0.55 kg/d, STH vs. ST, respectively; SE = 0.19). Average daily gain (ADG) was similar during the pre-weaning period but tended to be greater for STH calves during weaning. Calves in pens provided hay also had fewer unrewarded visits to the milk feeder during weaning (12.5 vs. 21.1 visits per 12 h, STH vs. ST, respectively; SE = 3.59) and performed less pen-directed sucking (9.11 vs. 19.3 min per 12 h, STH vs. ST, respectively; SE = 2.86). Self-grooming time and bout characteristics evolved differently between treatments over time, with pens of calves provided hay having a greater increase in frequency and duration of self-grooming bouts during weaning. Overall, we found that providing hay to pre-weaned calves resulted in behavioral and performance benefits, including greater total feed intake and reductions in pen-directed sucking, suggesting that access to hay may improve calf welfare.     

Associations between management practices and within-pen prevalence of calf diarrhea and respiratory disease on dairy farms using automated milk feeders

Data on management practices used with automated milk feeders (AMF) are needed to identify factors associated with calf health in these systems. The objectives of this observational, longitudinal, cross-sectional study were to estimate the prevalence of calf diarrhea (CD) and bovine respiratory disease (BRD), and to identify factors associated with prevalence of these diseases at the pen level on dairy farms feeding milk to group-housed calves with AMF. Seventeen dairy farms with AMF in Ontario, Canada, were visited 4 times, seasonally, over 1 yr. The clinical health of all calves (n = 1,488) in pens (n = 35) with AMF was scored to identify the number of calves with CD and BRD. Data on calf, feeder, and pen management practices were analyzed using generalized linear mixed regression models for each disease. Overall calf-level prevalence of CD and BRD were 23 and 17%, respectively. Median (interquartile range, IQR) within-pen prevalence of CD and BRD were 17% (7 to 37%) and 11% (0 to 28%), respectively. Median age (IQR) for diarrheic calves was 25 d (16 to 42 d), and for calves with BRD was 43 d (29 to 60 d). Factors associated with lower within-pen prevalence of CD were the administration of vitamin E and selenium at birth [odds ratio (OR) = 0.56; 95% confidence interval (CI): 0.32 to 0.99], feeding of probiotics (OR = 0.44, 95% CI: 0.22 to 0.93), and adding fresh bedding every 2 to 3 d (OR = 0.43; 95% CI: 0.24 to 0.76) compared with every 7 or more days. In contrast, sharing air with older cattle (>9 mo old) was associated with increased within-pen prevalence of CD (OR = 4.54, 95% CI: 1.88 to 10.52). Additionally, total bacteria counts ≥100,000 cfu/mL in milk samples taken from the AMF mixing jar were associated with increased within-pen prevalence of CD during the summer visit (OR = 3.34; 95% CI: 1.31 to 8.54). Increased total solids in milk or milk replacer (OR = 0.48, 95% CI: 0.27 to 0.85) and feeding whole milk versus milk replacer (OR = 0.29, 95% CI: 0.11 to 0.75) were associated with lower within-pen prevalence of BRD. Factors associated with greater within-pen prevalence of BRD were sharing air with weaned cattle up to 8 mo old (OR = 3.21, 95% CI: 1.26 to 8.16), and greater depth of the wet bedding pack. The use of maternity pens for reasons other than just calving was associated with increased prevalence of both CD and BRD (OR = 1.85, 95% CI: 1.03 to 3.33; OR = 2.61, 95% CI: 1.21 to 5.58, respectively). These results suggest that isolation from older animals and frequent cleaning of the feeder and pen may help to reduce disease prevalence in group-housed calves fed with an AMF.     

The effects of milk feeding method and group size on feeding behavior and cross-sucking in group-housed dairy calves

This study investigated the effect of teat feeding and group size on cross-sucking and competition for milk in dairy calves. Ninety-six Holstein-Friesian male and female calves were allocated to either pairs or groups of 6 and fed milk either from a bucket or via a teat. Calves fed via a teat spent more time ingesting the milk. They spent time sucking the empty teat after milk intake and they spent less time cross-sucking compared with calves fed from buckets. The results show that teat feeding reduces cross-sucking in groups of 6 calves. Calves in groups of 6 ingested the milk faster than calves housed in pairs, which suggests that the competition for milk was greater than in pairs. Teat-fed calves changed to another teat more often than bucket-fed calves changed to another bucket during milk intake. Thus, the use of teat feeding did not reduce the competition for milk as compared with bucket feeding and future studies should focus on improving teat-feeding methods so that they reduce competition for milk in group-housed calves.     

Computer-controlled milk feeding of group-housed calves: the effect of milk allowance and weaning type

Calves fed by computer-controlled milk feeders are often weaned gradually by reducing the size of the milk portions. However, reducing the number of milk portions instead may lower calves’ occupation of the milk feeder and stimulate their concentrate intake, especially when they are offered a high milk allowance. Before weaning, but not during weaning, the calves on low milk allowance occupied the milk feeder more, consumed more concentrates, and had a lower daily gain. There was no interaction between milk allowance and weaning type. Weaning by reducing the number of milk portions resulted in more unrewarded visits to the milk feeder, but less time ingesting a similar amount of milk. The effect of milk allowance on milk feeder occupancy before weaning was not found when this allowance was halved during weaning.     

Meal patterns of weaned dairy calves are affected by previous dietary experience and associated with competition surrounding individual feed bins

The objective of this study was to evaluate how meal patterns of recently weaned and group-housed dairy calves are subject to effects of previous dietary experience and associated with competition for feed. During the preweaning period, Holstein heifer and bull calves were provided diets differing in provision and presentation of forage as follows: (1) pelleted starter only (n = 12), (2) starter and chopped coastal bermudagrass provided in separate buckets (n = 13), (3) starter and chopped coastal bermudagrass mixed together in the same bucket (n = 15), or (4) starter, chopped coastal bermudagrass, and liquid molasses mixed together in 1 bucket (n = 13). At 58 ± 2 (mean ± standard deviation) days of age, following weaning, calves were mingled between treatments and moved into group housing in weekly age-based cohorts (7 ± 2 calves/group; 8 groups total), and all were provided the mixed diet (without molasses). Within group pens, calves were fed individually using the Calan Broadbent feeding system (American Calan Inc.). Calves were monitored for 1 wk following introduction to the group pen. Feed intake was measured daily. Behavioral data, describing feeding times and competition for feed, were recorded continuously for 48 h beginning after a 5-d adaptation to the group pen. Calves previously provided starter only had longer, less frequent meals than calves previously provided forage in any form, and they tended to consume less feed compared with those previously provided starter and hay separately, with calves previously provided mixed diets having intermediate intakes. We observed occurrences of displacements at bins, which were followed by replacements and feed stealing on some occasions, where 34% of calves consumed feed from a bin assigned to another calf on at least 1 occurrence, and 64% of calves were stolen from at least once. Competition at feed bins was not affected by previous dietary treatments, but was associated with meal patterns. Actor displacement rate was negatively associated with meal frequency and duration, but calves that were displaced more often were those that spent more time feeding. These results suggested a possible carryover effect of previous exposure to forage on postweaning meal patterns following a dietary change. Further, we found that competitive behavior varied considerably between individuals, occurring frequently despite feeding calves using individually-assigned feeding bins, and was associated with meal characteristics. These results highlighted the importance of considering both previous dietary experience and social factors when evaluating feeding behavior.     

Evaluation of applying statistical process control techniques to daily average feeding behaviors to detect disease in automatically fed group-housed preweaned dairy calves

Group housing and computerized feeding of preweaned dairy calves are gaining in popularity among dairy producers, yet disease detection remains a challenge for this management system. The aim of this study was to investigate the application of statistical process control charting techniques to daily average feeding behavior to predict and detect illness and to describe the diagnostic test characteristics of using this technique to find a sick calf compared with detection by calf personnel. This prospective cross-sectional study was conducted on 10 farms in Minnesota (n = 4) and Virginia (n = 6) utilizing group housing and computerized feeding from February until October 2014. Calves were enrolled upon entrance to the group pen. Calf personnel recorded morbidity and mortality events. Farms were visited either every week (MN) or every other week (VA) to collect calf enrollment data, computer-derived feeding behavior data, and calf personnel–recorded calf morbidity and mortality. Standardized self-starting cumulative sum (CUSUM) charts were generated for each calf for each daily average feeding behavior, including drinking speed (mL/min), milk consumption (L/d), and visits to the feeder without a milk meal (no.). A testing subset of 352 calves (176 treated, 176 healthy) was first used to find CUSUM chart parameters that provided the highest diagnostic test sensitivity and best signal timing, which were then applied to all calves (n = 1,052). Generalized estimating equations were used to estimate the diagnostic test characteristics of a single negative mean CUSUM chart signal to detect a sick calf for a single feeding behavior. Combinations of feeding behavior signals were also explored. Single signals and combinations of signals that included drinking speed provided the most sensitive and timely signal, finding a sick calf up to an average (±SE) of 3.1 ± 8.8 d before calf personnel. However, there was no clear advantage to using CUSUM charting over calf observation for any one feeding behavior or combination of feeding behaviors when predictive values were considered. The results of this study suggest that, for the feeding behaviors monitored, the use of CUSUM control charts does not provide sufficient sensitivity or predictive values to detect a sick calf in a timely manner compared with calf personnel. This approach to examining daily average feeding behaviors cannot take the place of careful daily observation.     

Effects of providing water from a bucket or a nipple on the performance and behavior of calves fed ad libitum volumes of acidified milk replacer

Little information is available on how much water ad libitum milk-fed calves consume during the milk-feeding stage and during weaning to solid feed. Further, no information exists on the effects on calf behavior and performance of different water delivery systems during these stages. Therefore, the objectives of this study were first, to examine the water intake of calves fed acidified milk replacer ad libitum during the milk-feeding and weaning stages, and second, to determine whether the method of water delivery affected water and feed intake and growth during these periods or oral behavior during weaning. To evaluate this, we registered feed and water intake, growth, and oral behaviors of 24 dairy calves before and after abrupt weaning from a 7-wk ad libitum acidified milk replacer feeding regimen. Two water sources (open bucket and nipple) were compared. During the 7-wk milk-feeding period, the calves drank, on average, 12.9 ± 0.7 L/d of acidified milk replacer but very little water. However, after abrupt removal of milk, the 2-mo-old calves rapidly increased their water intake. Moreover, no differences in water intake between the 2 water sources were noted either before or after abrupt weaning. Calves were observed to have some difficulties in using the water nipple. Calves provided water through the nipples consumed less water at each drinking bout but visited the water nipple more frequently compared with calves provided access to water from the bucket. We observed no differences in all other behaviors observed. Overall, the calves rapidly increased their feed intake, rumination time, frequency of cross-sucking, and vocalization after weaning. In conclusion, despite the calves’ consuming very little water when provided ad libitum access to acidified milk replacer, they dramatically increased their water consumption after abrupt weaning from milk. Calves did experience some difficulties in using the water nipples.     

Associations between feeding behaviors collected from an automated milk feeder and disease in group-housed dairy calves in Ontario: A cross-sectional study

The adoption of automated milk feeders and group housing of preweaning dairy calves has become more common in Canada; however, disease detection in group-housed calves remains a challenge. The aim of this cross-sectional study was to assess whether feeding behavior data collected from a single point in time could be used to aid in the detection of neonatal calf diarrhea (NCD), bovine respiratory disease (BRD), and general disease, in preweaning group-housed calves being fed via an automated milk feeder. The data used was collected in an earlier study. A total of 8 dairy farms recruited from an online survey of calf-management practices were enrolled into the study. There was a total of 523 observations with 130 events of NCD, 115 events of BRD, and 210 events of general disease. Each farm was visited once in each of the fall, winter, spring, and summer, when the calves' health was scored, and the data were collected from the automated milk feeders. Mixed linear regression models were used to identify associations between feeding behavior data (milk consumption, time spent at the feeder, drinking speed, and the number of rewarded and unrewarded visits) and the presence of NCD, BRD, or general disease (having one or more of NCD, BRD, or umbilical infection), on the day of health scoring. Generalized linear mixed models were used to analyze the percentage of milk the calf consumed from their daily milk allotment. Calves with BRD consumed 63% less of their daily allotment of milk, had 2 fewer unrewarded visits to the automated milk feeder, and drank milk 152 mL/min slower compared with calves without BRD. Calves with NCD consumed 57% less of their daily milk allotment, consumed 758 mL less per day, and drank 92 mL/min slower than calves compared with calves without NCD. Calves with general disease drank 50% less of their daily milk allowance, consumed 496 mL less per day, drank 80 mL/min slower, and had 2 fewer unrewarded visits to the automated milk feeder, when compared with calves without disease. No significant associations were found between the presence of NCD, BRD, or general disease and time spent at the feeder or number of rewarded visits. Sensitivity and specificity values for disease identification were low when evaluating the feeding behaviors individually, so parallel testing was completed. To do so, if any significant feeding behavior was below the optimal cut point for disease detection as determined using a ROC curve, the calf was considered positive for disease and the sensitivity and specificity were recalculated. Parallel testing resulted in a sensitivity of 0.82, 0.78, and 0.84, and a specificity of 0.26, 0.23, and 0.21, for BRD, NCD, and general disease, respectively. This suggests that automated milk feeders may serve as a useful preliminary tool in the detection of diseased calves. For example, producers could use feeding behavior data to identify calves requiring further inspection; however, they should not use feeding behavior data as a sole disease detection method.     

Computer-controlled milk feeding of dairy calves: the effects of number of calves per feeder and number of milk portions on use of feeder and social behavior

One hundred ninety-two calves (Holstein-Friesian, Danish Red, and Jersey) were allocated to either groups of 24 calves or groups of 12 calves with one computer-controlled milk feeder per group. Within group, one-half of the calves were offered the daily milk allowance in either 4 or 8 milk portions. In groups with 24 calves, there was a higher level of competition for access to the feeder than in groups with 12 calves. Calves waited longer for access, and while occupying the feeder, they were more often disturbed by other calves attempting to access the feeder. The increased level of competition resulted in a higher rate of milk ingestion among calves in groups of 24 and, as a result, a lower duration of time spent ingesting the milk and a lower occupation of the feeder per calf. The number of calves per feeder did not affect the amount of milk ingested, but the high level of disturbance and the increased feeding rate with 24 calves per feeder suggest that these calves were subject to social constraint. Offering the same milk allowance in 4 rather than 8 milk portions lowered the occupancy of the feeder. The number of portions did not affect the duration of ingesting milk, but the duration of occupying the feeder just after milk ingestion was lower with 4 than with 8 milk portions. Thus, fewer and larger portions may lower competition for access during the activity periods if all other factors remain equal.     

Antibiotic resistance in gut bacteria from dairy calves: a dose response to the level of antibiotics fed in milk

Dairy calves are commonly fed milk from cows treated with antibiotics. The concentration of beta-lactam antibiotic residues found in milk from treated cows was used to determine the range of concentrations of penicillin used in a dose-regulated experiment. Thirty-one Holstein calves were randomly assigned to milk with penicillin G added at concentrations of 0, 6.25, 12.5, 25, and 50 microl/kg. Fecal swabs were taken from each calf twice weekly. Resistance to penicillin was tested by measuring the zone of inhibition in bacterial growth around a disk impregnated with the antibiotic. Inhibition was greatest for bacteria from calves fed milk with no penicillin (2.89 +/- 0.14 mm), and declined as the penicillin dose provided in the milk increased (to a low of 0.70 +/- 0.10 for the 50 microl/kg treatment group). In conclusion, resistance of gut bacteria to antibiotics increases with increasing concentrations of penicillin in the milk fed to dairy calves.