Effects of OmniGen AF feed supplementation on glucocorticoids, blood leukocyte messenger RNA abundance, and energy metabolism in overstocked Holstein dairy cows.

The physiological consequences of overstocking require more investigation, and no research has explored whether dietary supplements could mitigate the anticipated negative physiological effects. OmniGen AF (OG, Phibro Animal Health Corporation, Teaneck, NJ, USA) is a nutritional supplement that has been shown to support the immune system of cattle following internal and environmental stressors. This study aimed to determine if a 45-day period of OG feed supplementation would influence whole blood leukocyte messenger RNA abundance, energy metabolism and glucocorticoid concentration, during a two-week period of overstocking. Two stocking density treatments (control: one headlock and lying stall per cow; overstocked: 0.5 headlocks and 0.5 lying stalls per cow) and two diet treatments (control: no added supplement; and OG: 56 g/cow per day) were investigated. Four pens of 15 cows were fed their assigned diet (two pens per diet; control stocking density) for 45 days after which each stocking density treatment was applied for a 14-day period using a cross-over design; this study design was replicated twice. During each 14-day period, blood was collected on day four to measure whole blood leukocyte messenger RNA abundance (cluster of differentiation 80, interleukin 8 receptor-beta, interleukin 10 receptor-beta and L-selectin) and fecal samples were collected every two days to measure fecal cortisol metabolite concentration (11,17-dioxoandrostanes). At the end of each 14-day period, eight cows from each pen were selected for an intravenous glucose tolerance test; glucose, insulin and non-esterified fatty acids were measured. There were no effects of diet or stocking density on leukocyte messenger RNA abundance. Fecal cortisol metabolite concentrations were highest for overstocked cows on the control diet on day four of the stocking density treatment; however, by day 10, overstocked cows fed OG had the highest fecal cortisol metabolite concentrations. Overstocked cows, regardless of diet, had an attenuated insulin response during the glucose tolerance test, represented by a lower area under the curve estimate. Cows fed OG but not overstocked, had a lower non-esterified fatty acid nadir during the glucose challenge, compared to all the other treatments. In conclusion, overstocking prompts a physiological stress response and alters energy metabolism by decreasing the insulin response to an intravenous glucose challenge. Feeding OG during overstocking delayed the increase in fecal cortisol metabolites by several days; however, it is unclear if this altered glucocorticoid response benefited the cow, as OG had no effect on insulin responses or immune parameters.

Associations between peripartum lying and activity behaviour and blood non-esterified fatty acids and ß-hydroxybutyrate in grazing dairy cows.

During early lactation, most dairy cows experience negative energy balance (NEB). Failure to cope with this NEB, however, can place cows at greater risk of developing metabolic disease. Our objective was to characterise, retrospectively, lying behaviour and activity of grazing dairy cows grouped according to blood non-esterified fatty acids (NEFAs) and ß-hydroxybutyrate (BHB) as indicators of postpartum metabolic state. Blood was sampled weekly for up to 4 weeks precalving, on the day of calving (day 0), daily between 1 and 4 days postcalving, and then at least weekly between week 1 and week 5 postcalving for analysis of plasma NEFAs and BHB concentrations. Two hundred and forty-four multiparous Holstein-Friesian and Holstein-Friesian × Jersey cows were classified into one of three metabolic status groups based on maximum blood NEFAs and BHB concentrations during week 1 and 2 postcalving. A cow was classified as having either: (1) low NEFAs and low BHB (Lo-Lo; n = 78), when all blood samples were <1.0 mmol/L for NEFAs and ≤1.0 mmol/L for BHB during the first 2 weeks postcalving; (2) high NEFAs and low BHB (Hi-Lo; n = 134), when blood NEFAs were ≥1.0 mmol/L and blood BHB was ≤1.0 mmol/L at the same sampling time point during the first 2 weeks postcalving; or (3) high NEFAs and high BHB (Hi-Hi; n = 32), when blood NEFAs were ≥1.0 mmol/L and blood BHB was ≥1.2 mmol/L at the same sampling time point during the first 2 weeks postcalving. Accelerometers (IceTag or IceQube devices; IceRobotics Ltd.) were used to monitor lying and activity behaviours peripartum (-21 to +35 days relative to calving). Changes in lying behaviour and activity occurred before the mean day that cows were classified Hi-Hi and Hi-Lo (2.2 and 3.5 d postcalving, respectively). Up to 3 weeks preceding calving, Hi-Hi cows were more active, had fewer daily lying bouts (LBs), and spent less time lying than Lo-Lo cows. In addition, Hi-Hi cows had fewer daily LBs and were less active up to 4 weeks postcalving than Lo-Lo cows, but these differences were biologically small. Groups of grazing cows classified as experiencing a more severe metabolic challenge behave differently up to 3 weeks precalving than their herdmates with lower blood NEFAs and BHB postcalving. These altered behaviours may allow identification of individual cows at risk of a metabolic challenge, but further research is required.

Graduate Student Literature Review: Evaluating the appropriate use of wearable accelerometers in research to monitor lying behaviors of dairy cows.

Until recently, animal behavior has been studied through close and extensive observation of individual animals and has relied on subjective assessments. Wearable technologies that allow the automation of dairy cow behavior recording currently dominate the precision dairy technology market. Wearable accelerometers provide new opportunities in animal ethology using quantitative measures of dairy cow behavior. Recent research developments indicate that quantitative measures of behavior may provide new objective on-farm measures to assist producers in predicting, diagnosing, and managing disease or injury on farms and allowing producers to monitor cow comfort and estrus behavior. These recent research developments and a large increase in the availability of wearable accelerometers have led to growing interest of both researchers and producers in this technology. This review aimed to summarize the studies that have validated lying behavior derived from accelerometers and to describe the factors that should be considered when using leg-attached accelerometers and neck-worn collars to describe lying behavior (e.g., lying time and lying bouts) in dairy cows for research purposes. Specifically, we describe accelerometer technology, including the instrument properties and methods for recording motion; the raw data output from accelerometers; and methods developed for the transformation of raw data into meaningful and interpretable information. We highlight differences in validation study outcomes for researchers to consider when developing their own experimental methodology for the use of accelerometers to record lying behaviors in dairy cows. Finally, we discuss several factors that may influence the data recorded by accelerometers and highlight gaps in the literature. We conclude that researchers using accelerometers to record lying behaviors in dairy cattle should (1) select an accelerometer device that, based on device attachment and sampling rate, is appropriate to record the behavior of interest; (2) account for cow-, farm-, and management-related factors that could affect the lying behaviors recorded; (3) determine the appropriate editing criteria for the accurate interpretation of their data; (4) support their chosen method of recording, editing, and interpreting the data by referencing an appropriately designed and accurate validation study published in the literature; and (5) report, in detail, their methodology to ensure others can decipher how the data were captured and understand potential limitations of their methodology. We recommend that standardized protocols be developed for collecting, analyzing, and reporting lying behavior data recorded using wearable accelerometers for dairy cattle.

Associations between lying behavior and activity and hypocalcemia in grazing dairy cows during the transition period.

Hypocalcemia is a common metabolic disorder of transition dairy cows that is considered a gateway disease, increasing the risk of other health disorders and reducing cow performance. Clinical milk fever is associated with long periods of recumbency, and it is plausible that cows experiencing non-paretic hypocalcemia may spend more time lying; hence, lying behavior and activity measures may be useful in identifying at-risk cows. The objective of this study was to describe associations among blood calcium (Ca) status at calving and lying behavior and activity measures during the transition period in grazing dairy cows. Blood was sampled on the day of calving (d 0), and d 1, 2, 3, and 4 postcalving, and analyzed for total plasma Ca concentration. Twenty-four multiparous Holstein-Friesian and Holstein-Friesian × Jersey grazing dairy cows were classified, retrospectively, as clinically hypocalcemic (CLIN; blood Ca ≤ 1.4 mmol/L at 1 or more consecutive samplings within 48 h postcalving, but without parturient paresis). These cows were pair-matched (using milk production potential from their estimated breeding value for milk protein, mean body weight at wk -5 and -6 precalving, and, where possible, parity) with 24 cows classified as subclinically hypocalcemic (SUB; blood Ca > 1.4 and < 2.0 mmol/L at 2 consecutive samplings within 48 h postcalving), and 24 cows classified as normocalcemic (NORM; blood Ca ≥ 2.0 mmol/L at 3 consecutive samplings within 72 h postcalving). Lying behavior and activity were monitored using triaxial accelerometers from -21 to +35 d relative to calving. Data were summarized to calculate daily lying time (h/d), daily number of lying bouts (LB; no./d), mean LB duration (min/bout), and the number of steps taken (steps/d). On d 0, the CLIN group were less active and spent approximately 2.6 h longer lying than the SUB and NORM groups, particularly between 0200 and 1400 h. On d 0, the NORM group had fewer LB (16.3/d) than the SUB and CLIN groups (18.2 and 19.2/d, respectively). These differences in behavior were no longer detected 2 d postcalving, and no further differences were observed. The day before calving, the CLIN group spent 1.4 h longer lying down than did the SUB and NORM groups. Further, the relative change in steps from a precalving baseline period (d -14 to -7) until d 0 was positively, linearly associated with blood Ca concentration within 24 h postcalving. Future work should consider daily and temporal changes in behavior in individual cows to determine the potential for these measures to allow early detection of hypocalcemia.

Changes in behavior and fecal cortisol metabolites when dairy cattle are regrouped in pairs versus individually after calving.

Regrouping occurs when dairy cows are moved between pens, and this can negatively affect cow behavior and production. Pen changes occur frequently around calving, a time when cows are vulnerable to health problems. Regrouping cows along with a familiar conspecific after calving may make social integration easier, but little work has tested this hypothesis. The objective of this study was to compare lying behavior, feeding behavior, social behavior, and fecal cortisol metabolite concentrations (a physiological indicator of stress) between cows regrouped individually and cows regrouped with a familiar partner after calving. Holstein (n = 8) and Jersey (n = 26) cows were monitored from approximately 2 wk before until 7 d after calving. Cows were held in 1 of 2 identical maternity pens until they calved. After calving, cows were held in a transition pen for 3 d before being regrouped into the main lactation pen (regrouping of interest). On d 3 postpartum, cows were assigned to a treatment, balancing for parity and breed: regrouped into the lactation pen alone (individual; n = 17) or with a familiar partner (paired; n = 17). A familiar partner was defined as a cow that spent 3 d in the transition pen with the focal cow. Using live observation, we quantified the time cows spent feeding, standing or lying in the lying stalls, grooming, and standing in different locations in the pen during the 1 h immediately after regrouping. The frequency of competitive interactions at the feed bunk was also measured during this observation period. Lying behavior was monitored from 2 d before until 5 d after regrouping using a data logger. Fecal samples were collected for 5 d beginning on the day of regrouping to assess fecal cortisol metabolite concentrations (11,17-dioxoandrostane, 11,17-DOA). We found no effects of regrouping treatment on behaviors observed during the 1-h period immediately following regrouping. Cows that were regrouped with a partner had more lying bouts than cows moved individually (9.2 ± 0.4 bouts/d vs. 7.5 ± 0.4 bouts/d) and shorter lying bout durations (66.6 ± 3.9 vs. 78.1 ± 3.5 min/d); however, we also observed these differences during the day before regrouping, suggesting that the differences in lying behavior could not be explained by the regrouping treatment alone. Individually regrouped primiparous cows had higher 11,17-DOA concentrations than individually regrouped multiparous cows but we found no differences in 11,17-DOA between parities when cows were moved with a familiar partner. In addition, 11,17-DOA was higher in primiparous cows moved alone compared with primiparous cows moved with a partner. More research is needed to understand the mechanisms by which social familiarity affects behavior and the physiological stress response following regrouping; this may provide new insight into how to better transition cows into new environments.

Lying behavior and activity during the transition period of clinically healthy grazing dairy cows.

Lying behavior and activity may provide useful information for the prediction of an imminent calving and the health of transition dairy cows; however, it is important first to understand what constitutes typical lying behavior and activity because this has not been defined for grazing dairy cows during the transition period. Our objective was to describe changes in lying behavior and activity in grazing dairy cows during the transition period using varying phenotypes typical of commercial dairy herds under grazing systems. Behavior data from IceTag or IceQube (IceRobotics, Edinburgh, Scotland) triaxial accelerometers were collected for 310 cow parities from multiparous, mixed-age (mean ± standard deviation; 4.5 ± 1.65 yr), and mixed-breed [Holstein-Friesian (HF), n = 216; and HF × Jersey, n = 94] grazing dairy cows from 4 parent experiments. The IceTags or IceQubes captured lying and activity data during the transition period (-21 to 34 d relative to calving) to allow the calculation of daily lying time (h/d), daily lying bouts (LB; no./d), mean LB duration (min/bout), and the number of steps taken (steps/d). Lying behavior and activity were analyzed using a repeated measures ANOVA during 3 periods: PRE (-21 to -3 d), POST (3 to 21 d), and the day of calving (d 0). Lying time was lower on d 0 (7.25 h/d) compared with PRE and POST lying times (10.3 and 8.58 h/d, respectively), with more frequent LB on d 0 (12.9 no./d) compared with the PRE and POST daily LB (8.15 vs. 7.74 no./d). Cows took more steps POST (4,424 steps/d) compared with d 0 and PRE (4,105 and 2,289 steps/d, respectively). Regression analysis determined that daily lying time decreased substantially from -3 to 0 d (slope = -1.03 ± 0.07 h/d) and from -2 and -1 d for daily LB (slope = 5.09 ± 0.54 no./d), which may be due to the calving event itself but also reflect restlessness. Daily lying time, daily LB, LB duration, and number of steps taken were substantially altered at the time of the calving event in grazing dairy cows. Cows were more active, spent less time lying, and took more steps postcalving compared with precalving, and it appears that this behavior may largely be due to activity associated with twice daily milking. Mean lying behavior and activity measures were more highly variable across individuals than across groups. Information available via activity monitors may contribute to the improvement of individual management of transition dairy cows, and this research provides a benchmark for typical changes in behavior during the transition period in grazing systems.

Behavioral changes before metritis diagnosis in dairy cows.

Metritis is common in the days after calving and can reduce milk production and reproductive performance. The aim of this study was to identify changes in feeding and social behavior at the feed bunk, as well as changes in lying behavior before metritis diagnosis. Initially healthy Holstein cows were followed from 3 wk before to 3 wk after calving. Behaviors at the feed bunk were recorded using an electronic feeding system. Lying behavior was recorded using data loggers. Metritis, based upon the characteristics of vaginal discharge at d 3, 6, 9, 12 and 15 after calving, was diagnosed in 74 otherwise healthy cows. Behavior of these cows, beginning 2 wk before calving until the day of diagnosis, was compared with 98 healthy cows (never diagnosed with any health disorder, including ketosis, mastitis, and lameness) during the transition period. During the 2 wk before calving, cows later diagnosed with metritis had reduced lying time and fewer lying bouts compared with healthy cows. In the 3 d before clinical diagnosis, cows that developed metritis ate less, consumed fewer meals, were replaced more often at the feed bunk, and had fewer lying bouts of longer duration compared with healthy cows. We concluded that changes in feeding as well as social and lying behavior could contribute to identification of cows at risk of metritis.

Changes in feeding, social, and lying behaviors in dairy cows with metritis following treatment with a nonsteroidal anti-inflammatory drug as adjunctive treatment to an antimicrobial.

Dairy cows with metritis display sickness behaviors, and nonsteroidal anti-inflammatory drugs (NSAID) have the potential to reduce these responses. The objective of this study was to investigate changes in feeding, social, and lying behaviors in dairy cows with metritis that had been treated with the NSAID meloxicam. After parturition, cows were housed in a dynamic, mixed-parity group of 20 animals with access to 12 electronic feed bins, 2 electronic water bins, and 24 lying stalls in a freestall pen. Every third day after parturition, vaginal discharge was evaluated to diagnose metritis based on the presence of foul smell and characteristic visual appearance. When diagnosed with metritis, animals (n = 87) were randomly allocated to receive either a single dose of meloxicam (0.5 mg/kg of body weight subcutaneously) or a placebo solution. All metritic animals received an antimicrobial (ceftiofur) for 5 d. We measured feeding and social behaviors at the feed bunk, as well as lying behaviors, and assessed within-cow changes from the day before to the day of (d 0) NSAID treatment, and from the day before to d 1 to 5 after treatment. Generally, behaviors changed around the day of diagnosis of metritis. Compared with the placebo group, cows that received meloxicam had a greater increase in the number of visits to the feeder, but tended to show less of an increase in dry matter intake and feeding time. These differences did not persist beyond 24 h after NSAID treatment. We observed no differences in changes in number of meals and feeding rate on d 0, but from d 1 to 5 cows treated with meloxicam had a lesser decrease in the number of meals and tended to have a greater decrease in feeding rate than did placebo-treated cows. In multiparous cows on d 0 and from d 1 to 5, meloxicam treatment was associated with decreased lying times. In primiparous cows, lying time changes were similar between treatments on d 0, but lying times increased more on d 1 to 5 for meloxicam than for placebo cows. Overall, cows changed the number of lying bouts on d 0, and this increase tended to be smaller for the meloxicam cows. There were no treatment differences in changes of social behavior. In summary, we observed inconsistent and generally small effects of a single dose of meloxicam in addition to antimicrobial therapy on the behavior of cows with metritis.

Clinical ketosis and standing behavior in transition cows.

Ketosis is a common disease in dairy cattle, especially in the days after calving, and it is often undiagnosed. The objective of this study was to compare the standing behavior of dairy cows with and without ketosis during the days around calving to determine if changes in this behavior could be useful in the early identification of sick cows. Serum ß-hydroxybutyrate (BHBA) was measured in 184 cows on a commercial dairy farm twice weekly from 2 to 21d after calving. Standing behavior was measured from 7d before calving to 21d after calving using data loggers. Retrospectively, 15 cows with clinical ketosis (3 consecutive BHBA samples >1.2mmol/L and at least one sample of BHBA >2.9mmol/L) were matched with 15 nonketotic cows (BHBA <1.2mmol/L). Five periods were defined for the statistical analyses: wk -1 (d -7 to -1), d 0 (day of calving), wk +1 (d 1 to 7), wk +2 (d 8 to 14), and wk +3 (d 15 to 21). The first signs of clinical ketosis occurred 4.5±2.1d after calving. Total daily standing time was longer for clinically ketotic cows compared with nonketotic cows during wk -1 (14.3±0.6 vs. 12.0±0.7h/d) and on d 0 (17.2±0.9 vs. 12.7±0.9h/d) but did not differ during the other periods. Clinically ketotic cows exhibited fewer standing bouts compared with nonketotic cows on d 0 only (14.6±1.9 vs. 20.9±1.8bouts/d). Average standing bout duration was also longer for clinically ketotic cows on d 0 compared with nonketotic cows [71.3min/bout (CI: 59.3 to 85.5) vs. 35.8min/bout (CI: 29.8 to 42.9)] but was not different during the other periods. Differences in standing behavior in the week before and on the day of calving may be useful for the early detection of clinical ketosis in dairy cows.

Short communication: Automatic detection of social competition using an electronic feeding system.

The objective of this study was to determine if data derived from a system that electronically monitors feeding behavior could be used to identify competitive interactions of dairy cows at the feed bunk. A short interval between successive feeding events of 2 cows at 1 feed bin was predicted to be associated with a competitive replacement: when one cow displaced a feeding cow and then took her position at the bin. To identify the interval between feeding events that best predicted these replacement events, the feeding activity of 5 Holstein dairy cows was monitored using an electronic feeding system and video recordings. The number of times a cow was replaced at the feed bunk over 3 consecutive 24-h periods was determined using video analysis and these events were paired with the corresponding feeding events recorded by an electronic feeding system (Roughage Intake Control system; Insentec B.V., Marknesse, the Netherlands). A pooled analysis of all 5 cows showed that the optimal interval for predicting replacements at the feed bunk was 26s (sensitivity=86% and specificity=82%); this interval was termed the replacement criterion. This criterion was then applied to feeding data from a sample of 24 independent Holstein dairy cows, each observed for 3d during the week following calving. Video had previously been used to measure the number of times each cow was an actor and reactor of a displacement (when one cow displaced a feeding cow but did not necessarily take her position at the bin). Despite the differences in measures, the number of replacements (as estimated by our algorithm) was positively correlated with the number of displacements [as measured using video; correlation coefficient (r)=0.63 as actor, r=0.69 as reactor]. Estimates of an index of success in competitive interactions (number of times actor/number of times actor = number of times reactor) generated using the 2 methods were highly correlated (r=0.94). These results suggest that competitive behavior at the feed bunk can be automatically quantified using data derived from an electronic feeding system.

Sampling behavior of dairy cattle: effects of variation in dietary energy density on behavior at the feed bunk.

Factors affecting sampling behavior of cattle are poorly understood. The objectives of this study were to measure the effects of variation in feed quality on the feeding behavior of Holstein dairy heifers. Thirty-two heifers were housed in 4 groups of 8. Each group pen had 8 distinct feeding stations. The total mixed ration (TMR) provided was low energy (TMR-L), moderate energy (TMR-M), or high energy (TMR-H). During trial 1 (d 1 to 8), heifers were offered a uniform baseline diet (TMR-M in all 8 feeding stations) interspaced with 2 uniform test diets on d 3 and 6 (TMR-L or TMR-H in all 8 feeding stations). During trial 2 (d 9 to 17) heifers were offered a nonuniform baseline diet (7 feeding stations with TMR-L and 1 feeding station with TMR-H) interspaced with 3 uniform test diets on d 11, 14, and 17 (TMR-L, TMR-M, or TMR-H in all 8 feeding stations). Heifers were observed in pairs (n=16) for 15 min following delivery of fresh feed. Relative to the uniform baseline period of trial 1, 31% fewer switches occurred between feeding stations when offered TMR-H and 51% more switches when offered TMR-L. Relative to the nonuniform baseline of trial 2, 49% fewer, 27% fewer, and 25% more switches occurred during the TMR-H, TMR-M, and TMR-L treatments, respectively. In general, when heifers were offered a diet that was lower in energy density than that previously experienced, they spent less time at each feeding station and when offered a higher energy diet, heifers spent more time at each feeding station. The greater the contrast in energy density between the test and baseline diets, the greater the change in the behavioral response. Competitive interactions at the feed bunk were most frequent when TMR quality varied among the 8 feeding stations; during the nonuniform baseline period of trial 2, the number of competitive interactions was over 3.5 times higher than during all uniform dietary treatments. In summary, dairy heifers sample feed quality by changing feeding locations at the feed bunk and this sampling behavior is affected by variation in diet quality along the feed bunk and across days.

Short communication: Relationship between competitive success during displacements at an overstocked feed bunk and measures of physiology and behavior in Holstein dairy cattle.

The objective of this study was to evaluate how behavioral and physiological parameters are affected based on a cow's level of success at displacing others at an overstocked feed bunk. Forty Holstein nonlactating, late-gestation dairy cattle were housed in an overstocked pen [5 stalls/10 cows and 0.34 m of linear feed bunk (FB) space/cow] in groups of 10 (4 heifers and 6 multiparous cows) for 14 d. Plasma nonesterified fatty acids, glucose, and fecal cortisol metabolites (11,17-dioxoandrostanes) were measured in blood and feces sampled every 2d. A glucose tolerance test and an ACTH challenge were conducted on all cows on d 13 and 14, respectively to further explore the effects of competitive success on energy metabolism and stress physiology. Feeding behavior and displacements at the FB were recorded between d 7 to 10 of the observation period. A competition index (CInd) was calculated for each cow by dividing the number of times the cow displaced another at the FB by the total number of displacements the cow was involved in, either as an actor or reactor. Cows were then divided into 3 subgroups based on their CInd: high success (HS: CInd ≥0.6), medium success (0.4 ≤ CInd <0.6), and low success (LS: CInd <0.4). Heifers accounted for 7, 36, and 79% of the total number of animals in the HS (n=15), medium success (n=11), and LS (n=14) groups, respectively. No differences were observed in daily feeding time, total number of displacements, and time to approach the FB following fresh feed delivery between the 3 CInd groups; however, cows in the LS group had greater daily nonesterified fatty acid and 11,17-dioxoandrostane concentrations relative to cows in the HS group. No differences existed in cortisol response to an ACTH stimulation test between CInd categories. During the glucose tolerance test, glucose response curves were the same between all 3 CInd categories; however, the peak insulin response of LS cows was 130 µIU/mL greater than the peak HS response, indicating that LS cows may have decreased tissue responses to insulin or increased pancreatic responses to glucose. In an overstocked environment, dairy cattle physiology is associated with a cow's level of success at displacing other individuals at the feed bunk.

The effects of overstocking Holstein dairy cattle during the dry period on cortisol secretion and energy metabolism.

The objective was to determine whether overstocking during the dry period could alter physiological parameters in dairy cattle associated with cortisol secretion and energy metabolism. Four groups of 10 late-gestation, nonlactating Holstein cows (6 multiparous cows and 4 heifers per group) were exposed to both a control [1 lying stall/cow and 0.67 m of linear feed bunk (FB) space/cow] and an overstocked (1 stall/2 cows and 0.34 m of FB space/cow) stocking density treatment in a replicated crossover design with 14-d treatment periods. On d 1, 3, 5, 7, 9, and 11 of each 14-d treatment period, blood and fecal samples were collected from each cow for the determination of plasma nonesterified fatty acids (NEFA), glucose, insulin, and fecal cortisol metabolite (11,17-dioxoandrostane; 11,17-DOA) concentrations. Glucose and ACTH challenges were conducted on d 13 and 14, respectively, of each treatment period. Dry matter intake per cow was greater during the overstocked period than during the control period (15.9 vs. 14.9 ± 0.5 kg/d). Plasma NEFA and glucose concentrations were greater (0.11 vs. 0.09 ± 0.006 mEq/L and 65.3 vs. 64.2 ± 1.1mg/dL, respectively) and 11,17-DOA concentration tended to be greater (891 vs. 792 ± 86 ng/g of fecal dry matter) during the overstocked period than during the control period. Insulin concentration was the same during the overstocked (29.0 ± 2.1 µIU/mL) and control (31.2 ± 2.1 µIU/mL) periods. Overstocking was associated with slightly slower glucose clearance from circulation as evidenced by a greater area under the curve estimate for the glucose response curves (2,882 vs. 2,657 ± 165 mg/dL × 180 min) but a more attenuated insulin response (insulin area under the curve = 5,258 vs. 6,692 ± 1,104 µIU/mL × 180 min for the overstocked and control periods, respectively). Changes in tissue glucose uptake may be mediated by changes in pancreatic insulin secretion or peripheral tissue responses to insulin. The role of glucocorticoids in mediating these changes in energy metabolism is still unclear because stocking density treatment was not associated with changes in adrenal secretion of cortisol following ACTH stimulation.

Associations of subclinical hypocalcemia at calving with milk yield, and feeding, drinking, and standing behaviors around parturition in Holstein cows.

The objectives of this study were to describe the associations of subclinical hypocalcemia with milk yield, and feeding, drinking, and resting behavior during the period around calving. Blood was sampled within 24h of calving and analyzed for serum total calcium. Fifteen Holstein dairy cows were classified as having subclinical hypocalcemia (serum calcium concentration ≤ 1.8 mmol/L, without clinical milk fever) and were matched with 15 control cows (serum calcium concentration >1.8 mmol/L) based on parity and presence of other diseases. Daily feeding and drinking behavior were monitored using an electronic feeding system (Insentec, BV, Marknesse, the Netherlands) and summarized by week relative to calving (wk -3, -2, -1, +1, +2, and +3). Standing behavior was monitored from 7 d before until 7 d after calving using dataloggers. Daily milk yields were obtained for all cows up to 280 d in milk (DIM). These data were summarized by week for the first 4 wk of lactation to assess short-term differences in milk yield, and were summarized into 4-wk periods to assess long-term (280 DIM) differences in milk yield between groups. Cows with subclinical hypocalcemia produced, on average, 5.7 kg/d more milk during wk 2, 3, and 4 compared with control cows; however, only subclinically hypocalcemic cows in their third lactation sustained greater milk yields throughout 280 DIM. Despite greater milk yield during the weeks following calving, cows with subclinical hypocalcemia did not consume more water after calving and tended to have greater dry matter intake only during wk 2. However, these animals made fewer visits to the water bins during the first 2 wk after calving and tended to make fewer visits to the feed bins during wk 1 and 3, suggesting that they used these resources more efficiently. Dry matter intake was, on average, 1.7 kg/d greater during wk -2 and -1 among cows subsequently diagnosed with subclinical hypocalcemia compared with control cows but neither group was lactating during this period. Cows with subclinical hypocalcemia stood for 2.6h longer during the 24-h period before parturition, which may suggest these animals experience increased discomfort at calving; these cows spent 2.7h less time standing during d +1. Although milk yield was greater among cows with subclinical hypocalcemia, this study controlled for the confounding effects of disease incidence; these results do not refute previous research that associates subclinical hypocalcemia with an increased risk for health disorders. The mechanisms by which subclinical hypocalcemia is associated with behavior and production require further investigation.

Associations of prepartum plasma cortisol, haptoglobin, fecal cortisol metabolites, and nonesterified fatty acids with postpartum health status in Holstein dairy cows.

The association between negative energy balance and health has led to the testing of blood analytes such as nonesterified fatty acids (NEFA) to identify opportunities for improving the management of transition dairy cows. The objective of this study was to evaluate whether prepartum analytes associated with stress (cortisol) or inflammation (haptoglobin) could also identify dairy cattle at increased risk for health complications after calving. Prepartum blood and fecal samples were collected once weekly from 412 Holstein dairy cows on 2 commercial dairy farms (at wk -3, -2, and -1 relative to calving) and analyzed for concentrations of NEFA, haptoglobin (Hp), and cortisol in plasma and cortisol metabolites in feces. Retained placenta (RP), displaced abomasum (DA), subclinical ketosis (SCK), high Hp concentration (HiHp), and death were recorded up to 30 d in milk (DIM), and animals were subsequently categorized into 3 health categories: (1) no disorder of interest (NDI); (2) one disorder (RP, DA, SCK, or HiHp); or (3) more than one disorder (RP, DA, SCK, HiHp) or death. With the exception of prepartum NEFA, no associations were detected between prepartum concentrations of our analytes of interest and the occurrence of one disorder (RP, DA, SCK, or HiHP) by 30 DIM. Haptoglobin concentration tended to be greater during wk -2 and -1 in cows that developed more than one disorder or that died by 30 DIM; however, when calving assistance was included as a covariate in the analysis prepartum, Hp was no longer a significant risk factor for this postpartum health outcome. Primiparous cows with plasma cortisol concentrations >22.2 nmol/L during wk -2 had reduced odds [odds ratio (OR) 0.41; 95% confidence interval (CI) 0.17-0.98] of developing more than one disorder or death by 30 DIM, whereas multiparous cows with plasma cortisol >34.1 nmol/L during wk -2 tended to have greater odds (OR 2.53; 95% CI 0.87-7.37) of developing more than one disorder or death by 30 DIM. Individual variation in daily cortisol secretion patterns and stress responses to the restraint and handling associated with sample collection make prepartum plasma cortisol data and its relationship to postpartum health difficult to interpret. Among multiparous cows, for every 500-unit (ng/g of fecal dry matter) increase in fecal cortisol metabolite concentration during wk -2, cows had increased odds (OR 1.41; 95% CI 1.12-1.79) of developing more than one disorder or dying after calving. For multiparous cows, every 0.15 mmol/L increase in plasma NEFA concentration during any of the 3 wk before calving was associated with an approximately 2-fold increase in the odds of developing more than one disorder or dying by 30 DIM. Fecal cortisol metabolite concentration during the prepartum period did not predict which cows would go on to develop more than one disorder or die within 30 DIM as accurately as prepartum NEFA concentration; therefore, this analyte is not a suitable substitute for NEFA for assessing opportunities to improve herd health.

The effect of dystocia on the dry matter intake and behavior of Holstein cows.

Dairy cows that have a difficult calf delivery (dystocia) are more likely to develop health complications after calving, reducing productivity and welfare. Understanding the behavioral cues of dystocia may facilitate prompt obstetric assistance and reduce the long-term effect of the challenging delivery. The aim of this study was to describe the effects of dystocia on dairy cow behavior during the period around calving and to assess the use of these behaviors as potential indicators of dystocia. Individual dry matter intake, water intake, feeding and drinking time, meal size, standing time, and number of transitions from standing to lying positions (bouts) were recorded during the 48-h period before and after the time of calf delivery for 22 Holstein cows [11 cows with dystocia and 11 cows with unassisted delivery (eutocia)]. Cows with dystocia consumed 1.9 kg less during the 48 h before calving compared with cows with eutocia (14.3 +/- 1.0 vs. 16.2 +/- 1.0 kg, respectively), and this difference increased to 2.6 kg in the 24 h before calving (8.3 +/- 0.7 vs. 10.9 +/- 0.7 kg/d). There were no differences in drinking time between the groups, but cows with dystocia consumed less water 24 h before calving (22.4 +/- 4.4 vs. 36.2 +/- 4.4 kg/d, respectively) and consumed more water during the 24-h period after calving (56.9 +/- 3.1 vs. 48.7 +/- 3.1 kg/d) compared with cows with eutocia. Cows with dystocia transitioned from standing to lying positions more frequently than cows without dystocia beginning 24 h before calving (10.9 +/- 0.7 vs. 8.3 +/- 0.7 bouts/d). Dry matter intake and standing bouts in the 24 h before calving were the most accurate variables in discriminating between cows with and without dystocia, suggesting that cows with dystocia begin to alter their behavior beginning 24 h before calving.

Short communication: Haptoglobin as an early indicator of metritis.

The purpose of this study was to determine whether haptoglobin (Hp) could be used as a predictive measure for metritis. Cattle were grouped into 3 health categories based on the condition of vaginal discharge and body temperature after calving: severe metritis (n = 12), mild metritis (n = 32), and healthy (n = 23). Blood was collected and analyzed for Hp concentration on d -20 +/- 5, -6 +/- 2, -2 +/- 1, and d 0 relative to calving, and then every 3 d after calving until d +21. Cows with mild and severe metritis had greater Hp concentrations than healthy cows between d 0 and d +12. Mean (+/-SE) Hp concentrations peaked on d +3 in the cows with mild metritis (1.06 +/- 0.15 g/L) and on d +6 in cows with severe metritis (1.62 +/- 0.47 g/L). Mean concentrations for the healthy group were 0.58 +/- 0.12 g/L and 0.31 +/- 0.08 g/L on d +3 and d +6, respectively. Clinical signs of pathological discharge for the mildly and severely metritic cows did not occur until, on average, 8.6 +/- 3.9 d and 5.3 +/- 1.9 d after calving, respectively. Cows with Hp concentrations >or=1 g/L on d +3 were 6.7 times more likely to develop severe or mild metritis; this predictive threshold has a sensitivity of 50% and specificity of 87%. These results indicate that an acute phase inflammatory response precedes clinical metritis and that Hp screening may assist in the early detection of metritis, providing increased opportunities for early treatment and prevention.

Board-invited review: Using behavior to predict and identify ill health in animals.

We review recent research in one of the oldest and most important applications of ethology: evaluating animal health. Traditionally, such evaluations have been based on subjective assessments of debilitative signs; animals are judged ill when they appear depressed or off feed. Such assessments are prone to error but can be dramatically improved with training using well-defined clinical criteria. The availability of new technology to automatically record behaviors allows for increased use of objective measures; automated measures of feeding behavior and intake are increasingly available in commercial agriculture, and recent work has shown these to be valuable indicators of illness. Research has also identified behaviors indicative of risk of disease or injury. For example, the time spent standing on wet, concrete surfaces can be used to predict susceptibility to hoof injuries in dairy cattle, and time spent nuzzling the udder of the sow can predict the risk of crushing in piglets. One conceptual advance has been to view decreased exploration, feeding, social, sexual, and other behaviors as a coordinated response that helps afflicted individuals recover from illness. We argue that the sickness behaviors most likely to decline are those that provide longer-term fitness benefits (such as play), as animals divert resources to those functions of critical short-term value such as maintaining body temperature. We urge future research assessing the strength of motivation to express sickness behaviors, allowing for quantitative estimates of how sick an animal feels. Finally, we call for new theoretical and empirical work on behaviors that may act to signal health status, including behaviors that have evolved as honest (i.e., reliable) signals of condition for offspring-parent, inter- and intra-sexual, and predator-prey communication.

Prepartum behavior and dry matter intake identify dairy cows at risk for metritis.

Metritis is a disease of particular concern after calving because of its profound negative effects on the reproductive performance of dairy cows. Cows at risk for metritis have shorter feeding times in the days before calving but prepartum dry matter intake (DMI) and water intake may also be useful in identifying cows at risk for this disease. Feeding, drinking, and intake measures may also be affected by social interactions among group-housed cows. The objective of this study, therefore, was to measure intake, feeding, drinking, and social behavior to determine which measures could identify cows at risk for metritis after calving. Feeding and drinking behavior and intake measures were collected from 101 Holstein dairy cows from 2 wk before until 3 wk after calving using an electronic monitoring system. Social behavior at the feed bunk was assessed from video recordings. Metritis severity was diagnosed based on daily rectal body temperature as well as condition of vaginal discharge that was assessed every 3 d after calving until d +21. In this study, 12% of cows were classified as severely metritic and 27% as mildly metritic. Prepartum feeding time and DMI were best able to identify cows at risk for metritis. Cows that developed severe metritis spent less time feeding and consumed less feed compared with healthy cows beginning 2 wk before the observation of clinical signs of infection. For every 10-min decrease in average daily feeding time during the week before calving, the odds of severe metritis increased by 1.72, and for every 1-kg decrease in DMI during this period, cows were nearly 3 times more likely to be diagnosed with this disorder. During the week before calving, cows that were later diagnosed with severe metritis had lower DMI and feeding times during the hours following fresh feed delivery. During this period these cows also engaged in fewer aggressive interactions at the feed bins compared with cows that remained healthy. This research is the first to show that social behavior may play an important role in transition cow health. Research is now required to determine how management should be changed to reduce or prevent illness in transition dairy cows.

Stocking density and feed barrier design affect the feeding and social behavior of dairy cattle.

The objectives of this study were to: 1) evaluate how stocking density at the feed bunk affects feeding and social behavior of dairy cows; and 2) determine if this effect is further influenced by the type of feed barrier used. Thirty-six lactating Holstein cows, allotted to 4 groups, were subjected to each of 4 stocking density treatments and 2 feed barrier treatments. Initially, 2 groups were assigned to a headlock barrier, and 2 groups to a post-and-rail barrier. Each group was then exposed to 4 stocking density treatments (0.81, 0.61, 0.41, and 0.21 m/cow, corresponding to 1.33, 1.00, 0.67, and 0.33 headlocks/cow), in 4 successive 10-d treatment periods. After these periods, the feed barriers were switched between groups and the 4 stocking density treatments were readministered. Time-lapse video was used to quantify feeding, standing, and aggressive behavior at the feed bunk. Daily feeding times were greater and duration of inactive standing in the feeding area was less when using a post-and-rail compared with a headlock feed barrier. Feeding time decreased and inactive standing increased for both barrier designs as stocking density increased at the feed bunk. Cows were displaced more often from the feeding area when the stocking density was increased, and this effect was greater for cows using the post-and-rail feed barrier. Cows ranked lower in the social hierarchy at the feed bunk were displaced more often when feeding at a post-and-rail barrier, particularly at high stocking densities. Therefore, we recommend avoiding overstocking at the feed bunk to increase feeding activity and reduce competition. Use of a barrier that provides some physical separation between adjacent cows, such as a headlock feed barrier, can be used to further reduce competition at the feed bunk.