Cattle are more motivated for a high-concentrate diet than Sudan grass hay, despite low reticulorumen pH.

Subacute ruminal acidosis (SARA) is characterized by chronic low ruminal pH, and occurs for feedlot cattle fed high-concentrate diets. Forages slow digestion and reduce acid production. We aimed to assess how motivated finishing cattle are to access forage (Sudan grass hay, SG) via their willingness to interact with an electrified barrier. Reticulorumen pH was measured to relate the results to digestive health. Twenty-eight animals fed a high-concentrate ration ad libitum had access to 4 L of one of two treatments (n = 14/treatment) fed 1×/d behind a barrier: 1) SG or 2) an additional offering of the normal ration (total mixed ration [TMR]). To access their treatment, the steer voluntarily pushed his muzzle against an electrified barrier. The electrical current was increased exponentially every 24 h (0, 156, 312, 625, 1,250, 2,500, 5,000 µA) until the animal ceased accessing it. Visits to the treatment were recorded continuously 24 h/d and reticulorumen pH was measured every 10 min. Time with a reticulorumen pH below 5.8 was 348 ± 101 and 280 ± 76 min/24 h for SG and TMR animals, respectively; these durations meet the criterion for SARA. However, animals with access to SG were less likely to advance to the next current than TMR animals (P < 0.01) and were approximately 3× less willing to interact with higher currents than TMR (mean maximum current touched: 469 ±â€…169 and 1,380 ±â€…254 µA, respectively, mean ±â€…SE, P = 0.01). Lower motivation to access SG was further demonstrated through fewer visits to the SG (2.4 ±â€…0.4 vs. 5.3 ±â€…0.6 #/d, P < 0.01), and less SG consumed than TMR (32.0 ±â€…0.1 vs. 74.0 ±â€…0.0 %/d, P < 0.01, measured as % due to weight differences of SG and TMR). Overall, finishing cattle valued the TMR more than SG, likely because of differences in the quantity offered, palatability, and familiarity. When rumen health was considered, SG animals visited more often (r = 0.5, P = 0.09) and showed fewer failed attempts (r = -0.5, P = 0.06) to access forage as the severity and duration of pH depression below 5.6, for example, increased. No measures of treatment use were related to pH depression for TMR animals (P ≥ 0.31). These findings provide evidence that cattle are motivated for Sudan grass hay when experiencing chronic low reticulorumen pH. However, they also contribute to the mixed evidence about the motivation for forage in this life stage, because, overall TMR was valued more highly than SG. Despite widespread pH depression, TMR cattle contrafreeloaded for additional concentration, demonstrating unexpectedly high motivation for this resource.

Feedlot cattle are at risk of subacute ruminal acidosis, a digestive disorder, because their diets are typically high in concentrates or grains and low in forages. Grains have the potential to be digested rapidly in the animals' rumen, causing an increase in acidity. In contrast, forages slow the rate of digestion and can prevent a rapid or chronic drop in rumen pH, thereby mitigating this problem. Our objective was to measure how motivated finishing cattle are to access Sudan grass hay when fed a high-concentrate diet. Cattle with free access to other feed accessed one of two treatments, either Sudan grass hay or additional grain, by voluntarily opening an electrified barrier. The current applied to the barrier increased exponentially every 24 h until the animal stopped touching it. Animals were simultaneously administered a wireless telemetry bolus to measure reticulorumen pH. Cattle offered Sudan grass hay and accessed the forage more often as pH depression increased in severity. However, cattle willingly interacted with a higher electric current to access grain than Sudan grass hay, despite experiencing chronic low reticulorumen pH.

Breed differences in oral behaviors in feed-restricted dairy heifers.

Holsteins and Jerseys, the 2 most prominent dairy breeds in the United States, differ in many regards. They have not been evaluated for differences in oral behavior performance, despite anecdotal evidence that Jerseys perform more abnormal behaviors than Holsteins. As abnormal behaviors can indicate compromised welfare, we evaluated whether breed differences existed in year-old heifers. Because many oral behaviors could be expressed in abnormal ways, we also sought to describe performance of a wide range of behaviors and whether these varied among individuals. We studied 42 pair-housed heifers (33 Holstein, 9 Jersey) at 12.8 ± 1.1 mo of age (mean ± SD) that were restricted to 50% of their ad libitum total mixed ration (TMR) intake for 2 d as part of a short-term feed challenge. Using continuous video recording from 0800 to 2000 h on the second day of feed restriction, we scored time spent performing tongue rolling, tongue flicking, self-grooming, allogrooming, intersucking, drinking urine, drinking water, and nonnutritive oral manipulation (NNOM) of rice hull bedding, the feed bin, or other pen fixtures. Eating TMR was recorded at 5-min intervals. We found that Jerseys spent more time tongue rolling (3.3% vs. 0.2% proportion of 12-h observations) and performing all types of NNOM than Holsteins (feed bin: 3.8% vs. 2.4%; bedding: 7.7% vs. 5.4%; other: 7.5% vs. 4.2%; total: 19.0% vs. 12.0%), and tended to spend more time tongue flicking (1.4% vs. 1.1%). Jerseys spent less time allogrooming than Holsteins (1.3% vs. 3.4%). There was no evidence of an effect of breed on self-grooming (2.0%), water drinking (1.0%), eating TMR (16.0%), or intersucking (0.06%). Urine drinking was performed by 9 total heifers and was not compared between breeds. All behaviors were highly variable across individuals, particularly tongue rolling and intersucking. Allogrooming was more variable than self-grooming, and each subcategory of NNOM was more variable than total NNOM. Outliers, or extreme performance of oral behaviors relative to the rest of our population, were present in most behaviors. Heifers who were outliers in one behavior were not consistently outliers in all. Overall, there are breed differences in many oral behaviors in a feed-restricted environment. Despite no difference in proportion of time spent eating, Jerseys often performed higher levels of potentially abnormal behaviors than Holsteins, though both breeds performed many oral behaviors, sometimes at extreme levels, that may indicate a concern.

Limit feeding total mixed rations exacerbates intersucking in year-old dairy heifers.

Limit feeding is a practice that is used to improve feed efficiency and control growth in dairy heifers, but also has negative consequences associated with hunger and restriction of feeding behavior. One such consequence could be intersucking (i.e., the licking or sucking of another animal's teats or udder). This behavior is reported to varying degrees in heifers, and thus, our first objective was to evaluate whether intersucking increased in response to short-term (48 h) feed restriction. Intersucking interventions, such as nose rings, are often applied to specific animals, and so our second objective was to describe intersucking performance in individual heifers, including those that represent outliers in this population. We studied 42 heifers (9 Jerseys, 33 Holsteins) aged 12.8 ± 1.1 mo (mean ± SD). They were housed in 21 pairs, the experimental unit for our first objective. We used a switchback design with 3 periods of 2 d each where heifers were fed ad libitum total mixed ration in the first and third periods (Baseline and Return, respectively), and limit fed to 50% of ad libitum intake in the second period (Restriction). We scored time spent intersucking continuously and eating at 5-min intervals from video recordings from 0800 to 2000 h on 4 d (baseline d 2, restriction d 2, return d 1, and return d 2). Heifer pairs spent less time eating (16 ± 0.4% mean percentage of 12-h observations ± SE), more time intersucking (27 ± 7 s/12 h), and engaged in longer bouts of intersucking (23 ± 5 s/bout) on Restriction d 2 compared with all other days (eating: 34.7 ± 1.1%, 44.2 ± 0.9%, 35.8 ± 1.1% of 12-h; intersucking time: 7 ± 2, 7 ± 3, 10 ± 5 s/12 h; intersucking bout length: 3 ± 1, 2 ± 1, 3 ± 1 s/bout; Baseline d 2, Return d 1, Return d 2, respectively). There was no difference in the number of bouts of intersucking across days (1.3 ± 0.2 bouts/12 h). The drop in eating during feed restriction was followed by a rebound on Return d 1 before returning to baseline levels. Time spent intersucking did not differ among ad libitum periods. Overall, 90% of the heifers performed intersucking on at least 1 of the 4 d, and did this for 1 to 127 s/12 h (range) in 1 to 13 bouts/12 h. Of the heifers that intersucked, 55% did this at extreme levels relative to the rest of the experimental population (outliers). Solid feed restriction exacerbated intersucking in year-old heifers, but this behavior was widespread.

Behavioral changes in the first 3 weeks after disbudding in dairy calves.

Hot-iron disbudding, the practice of cauterizing horn bud tissue to prevent horn growth in dairy calves, results in behavioral changes indicative of pain in the first few days after the procedure. However, few studies have quantified behavioral changes in the following weeks, while the burn wounds are still healing. Female Holstein calves were disbudded with a heated iron and pain relief (5.5 mL lidocaine cornual nerve block and 1 mg/kg oral meloxicam) at 4 to 10 d of age (n = 19) or not disbudded (n = 19). Calves wore ear tag accelerometers that reported the dominant behavior being performed at 1-min intervals from 3 to 21 d after disbudding. Compared with age-matched controls, disbudded calves tended to spend more time inactive throughout the observation period, ruminated less in the first 3 to 11 d after disbudding, and sucked more from a milk bottle beginning 5 d after disbudding until the end of the 21-d observation period. In addition to the accelerometer data, live observations of sleeping (using a behavioral proxy), lying, and ruminating were collected using instantaneous sampling at 5-min intervals for 24-h periods 3, 10, and 17 d after disbudding. Disbudded calves slept with their head down more on all live observation days and spent more time lying on the 17th d after disbudding, but ruminating did not differ compared with controls, in contrast to the accelerometer results. More time spent inactive, sleeping, and lying, and less time spent ruminating (as indicated by the accelerometer) can be interpreted as attempts to reduce painful stimulation of the disbudding wounds and allocate energy to healing. It is unclear whether the greater amount of sucking in the disbudded calves is nutritive (milk present) or non-nutritive (milk absent), as the algorithm did not distinguish the type of sucking, and further research is needed to explore the factors underlying this effect. We conclude that disbudding alters daily behavior patterns for at least 3 wk, far beyond the duration of recommended pain medication, raising additional welfare concerns about the procedure.

Development and application of a novel approach to scoring ear tag wounds in dairy calves.

Application of ear tags in cattle is a common husbandry practice for identification purposes. Although it is known that ear tag application causes damage, little is known about the duration and process of wound healing associated with this procedure. Our objective was to develop a detailed scoring system and use it to quantify wound healing in dairy calves with plastic identification tags. Calves (n = 33) were ear tagged at 2 d of age, and wound photos were taken weekly until 9 to 22 wk of age. This approach generated 10 to 22 observations per calf that were analyzed using a novel wound scoring system. We developed this system to score the presence or absence of external tissue types related to piercing trauma or mechanical irritation along the top of the tag (impressions, crust, and desquamation) and around the piercing (exudate, crust, tissue growth, and desquamation). Ears were scored as "piercing only" when tissue around the ear tag was intact. We found that impressions, crust, tissue growth, and desquamation were still seen in many calves by 12 wk of age. This suggests that extrinsic factors, such as mechanical disturbance and irritation, may have contributed to prolonged wound healing. Indeed, impressions along the top of tag, likely caused by rubbing against the ear, were observed for nearly the full duration of the study. Further research is warranted to understand ways to improve the ear-tagging process.

Wound healing and pain sensitivity following caustic paste disbudding in dairy calves.

Caustic paste disbudding is increasing in popularity on commercial dairy farms in the United States, but little research has explored the pain and welfare implications beyond the acute period of this procedure. In contrast, researchers have reported it takes 7 to 9 wk, on average, for hot-iron disbudding wounds to re-epithelialize in dairy calves. Our objective was to describe wound healing and sensitivity following caustic paste disbudding. Jersey and Holstein female calves were disbudded using caustic paste (H. W. Naylor Company Inc.) at 3 d of age (n = 18), and control calves received a sham procedure (n = 15). Before disbudding, calves received a local block and a nonsteroidal anti-inflammatory drug. Calves ≥34 kg and <34 kg at birth had 0.3 or 0.25 mL of paste applied per unshaved horn bud, respectively. Following disbudding, wounds were scored 2×/wk for the presence or absence of 8 tissue categories, including the final stages: new epithelium and fully healed. Control calves were removed from the experiment after 6 wk to be hot-iron disbudded. Mechanical nociceptive threshold (MNT) measures were collected weekly to evaluate wound sensitivity until calves were removed from the study or healed. Wounds were slow to re-epithelialize (16.2 ± 5.7 wk, mean ± SD; range: 6.2-32.5 wk) and contract to be considered fully healed (18.8 ± 6 wk, mean ± SD; range: 8.7-34.1 wk). Compared with non-disbudded controls, paste calves exhibited lower MNT values for all 6 wk (mean ± SE; control: 1.46 ± 0.16; paste: 1.18 ± 0.12 N). These data indicate that wounds from caustic paste disbudding are more sensitive than undamaged tissue for at least 6 wk and take twice as long to heal compared with cautery methods described in the literature. In conclusion, caustic paste disbudding wounds took 18.8 wk to fully heal and were more sensitive than intact horn buds for 6 wk. Future work should examine whether aspects of paste application (e.g., amount used, time rubbed in, calf age, pain mitigation) could improve healing time and sensitivity.

Early life access to hay does not affect later life oral behavior in feed-restricted heifers.

Dairy cattle are often raised in environments that lack natural feeding opportunities, and they perform abnormal repetitive behaviors (ARBs) as a result. Early life restriction can affect later life behavior. We evaluated whether access to hay in the milk-fed period would affect later life behavior in heifers experiencing short-term feed restriction and whether individuals were consistent in behavioral expression over time. We had 2 competing ideas about how this would unfold. First, being raised with hay, which reduced early life ARBs, could lead to fewer ARBs later in life. Alternatively, heifers that were raised without hay and performed more ARBs in early life might be more prepared for a later feed-restricted environment and thus engage in fewer ARBs than those raised with hay. We studied 24 pair-housed Holstein heifers. As calves, they were fed milk and grain from 0 to 7 wk of age (control) or given additional forage (hay). Tongue rolling, tongue flicking, nonnutritive oral manipulation (NNOM) of pen fixtures, self-grooming, and water drinking were recorded for 12 h (0800-2000 h) during wk 4 and 6 of life using 1-0 sampling at 5-s intervals. At the start of weaning at d 50, all calves were fed a total mixed ration. All calves were fully weaned at d 60 and socially housed by d 65 to 70. After this point, all individuals were raised the same way, according to farm protocol, in groups that included both treatments. At 12.4 ± 0.6 mo of age (mean ± standard deviation), heifers were restricted to 50% of their ad libitum total mixed ration intake for 2 d as part of a short-term feed challenge. Using continuous video recording from 0800 to 2000 h on d 2 of feed restriction, we scored time spent performing oral behaviors: the 5 previously scored while they were calves, along with intersucking, allogrooming, drinking urine, NNOM of rice hull bedding, and NNOM of feed bins. We found that early life access to hay did not affect behavior performed by heifers experiencing short-term feed restriction 1 yr later. Most heifers performed a wide variety of behaviors that appeared abnormal. All heifers performed tongue rolling and NNOM, and at higher levels than when they were calves, while tongue flicks and self-grooming were performed less by heifers. Individual performance of NNOM and tongue rolling were not related across age classes [correlation coefficient (r) = 0.17 and 0.11, respectively], but tongue flicks tended to be correlated (r = 0.37). Intersucking was recorded in 67% of heifers, despite their not being able to suckle a conspecific or dam in early life. Oral behaviors were highly variable across heifers, particularly tongue rolling and intersucking. Outliers, or extreme performance of oral behaviors relative to the rest of the population, were present for many behaviors. Most outliers were expressed by unique heifers that were not extreme in other behaviors. Overall, feeding individually housed, milk-limited calves hay for their first 7 wk did not affect later life performance of oral behaviors. The considerable variability, inconsistency across ages, and excessive performance of some behaviors raises additional questions about how these develop in cattle across life stages and about what we label "abnormal."

Response to novel feed in dairy calves is affected by prior hay provision and presentation method.

Animals raised in environments that prevent natural foraging opportunities may have difficulty adapting to novelty, such as feeding and management changes. Our objective was to evaluate how early provision and presentation of forage in dairy calves affected response to novel TMR (total mixed ration; grain and alfalfa) at weaning. Holstein heifer calves were housed individually in a covered outdoor hutch with an attached uncovered wire-fenced pen on sand bedding. Calves were fed a diet of starter grain and milk replacer (5.7-8.4L/d step-up) via a bottle (Control, n = 9) or given additional access to mountaingrass hay presented either in a bucket (Bucket, n = 9), or PVC pipe feeder (Pipe, n = 9). Treatments were applied from birth through 50 d of age, when step-down weaning began. All calves had 3 buckets and a pipe feeder provided in their uncovered pen area. On d 50, each calf was briefly blocked inside their hutch. TMR was put in the 3rd bucket that previously contained hay (Bucket) or was empty (Control, Pipe). The calf was released from the hutch and video-recorded for 30 min. Neophobia towards TMR was affected by prior experience with presentation: Bucket calves began eating TMR faster than Pipe and Control (P≤0.012) and showed the fewest number of startle responses (P = 0.004). Intake was similar across groups (P = 0.978), suggesting this apparent neophobia was transient, but Control calves took longer to eat than Bucket (P<0.001) and Pipe (P = 0.070) calves and were less likely to give up on eating to lie down instead. These results suggest that previous experience with hay improves processing ability when presented with novel TMR. Overall, response to a novel feed is affected by both early life experience, such as opportunities to process forage, and the presentation of the feed itself. Calves also appear motivated to access forage, evidenced by transient neophobia, high intake, and persistence in feeding by naïve calves.

Providing long hay in a novel pipe feeder or a bucket reduces abnormal oral behaviors in milk-fed dairy calves.

Many milk-fed dairy calves are not provided forage. In these settings, calves often perform abnormal repetitive behaviors (ARBs), including tongue rolling and nonnutritive oral manipulation (NNOM), which, based on their form, seem similar to movements used when processing feed. Feeding hay, typically presented as a short chop (≤5 cm) in a bucket, reduces ARBs. Our objective was to evaluate whether altering the presentation method of long hay (∼19 cm), by providing it in a bucket or a novel polyvinyl chloride (PVC) pipe feeder, could reduce ARBs. Holstein heifer calves were housed individually on sand and fed ad libitum starter grain and limited milk replacer (5.7-8.4 L/d step-up) via a bottle (Control, n = 9) or given access to mountaingrass hay in a bucket (Bucket, n = 9) or in a PVC pipe feeder (Pipe, n = 9). The 56 × 10.2 cm (length × diameter) PVC pipe feeder had 4 openings that were 6.35 cm wide, which required the calf to insert her tongue into the pipe and curl her tongue to extract hay. Treatments were applied from birth through 50 d of age, when step-down weaning began and TMR was provided to all calves. Calves were fully weaned at d 60. At wk 4 and 6, oral behaviors (eating, ruminating, drinking water, sucking milk, self-grooming, NNOM, tongue rolling, tongue flicking, and panting) were recorded by direct observation for 24 h using 1-0 sampling during 5-s intervals. Feeding long hay, regardless of presentation method, increased overall DMI, grain intake, and ADG compared with Control calves. Hay provision also increased rumination (25 vs. 15% of 24-h observations in Control) and eating time (5.5 vs. 2% in Control). Abnormal behaviors were seen in all calves. Hay provision reduced some of these, including NNOM (5 vs. 9% in Control). There was no difference in NNOM between calves fed hay in a pipe or bucket, even though Bucket calves consumed more hay (178 vs. 129 g/d in wk 6) and tended to spend more observations eating hay than Pipe calves (4.5 vs. 3%). Hay provision did not affect other behaviors: drinking water (0.5%), grooming (3%), or tongue flicking (3%). We also found evidence of other abnormal oral behaviors that have received less attention. Calves showed signs of polydipsia, and displayed excessive grooming, the latter indicated by overall duration, number of bouts per day, and duration of individual bouts (up to 25 min). Tongue rolling was expressed at low levels (up to 0.4% of intervals) but by 85% of calves. Feeding hay, both in a bucket and using novel methods, was not enough to counteract the welfare challenges associated with individual housing and limited ability to suck milk (<1% of time). Provision of long hay, regardless of presentation method, promotes rumination, improves performance (higher grain intake and ADG) and reduces at least some, but not all, of the considerable abnormal oral behaviors these calves performed.

Effect of plane of nutrition and analgesic drug treatment on wound healing and pain following cautery disbudding in preweaning dairy calves.

The objective of this study was to determine the effect of a biologically normal plane of nutrition compared with a limited plane on the primary outcome wound healing, and one dose of nonsteroidal anti-inflammatory drug (NSAID) compared with 2 on the secondary outcomes: lying behavior, haptoglobin concentrations, and mechanical nociceptive threshold (MNT) in calves disbudded via cautery iron. Eighty female Holstein calves were enrolled at birth, individually housed, and fed via a Calf Rail system (Förster Technik). A 2 × 2 factorial design was used to assess the effect of plane of nutrition and an additional NSAID. Calves were randomly assigned to a biologically normal plane of nutrition (BN; offered up to 15 L/d) or a limited plane (LP; offered up to 6 L/d) and to receive one or 2 doses of meloxicam. All calves received a lidocaine cornual nerve block and a subcutaneous injection of meloxicam 15 min before cautery disbudding at 18 to 25 d of age, and half the calves received an additional injection of meloxicam (0.5 mg/kg) 3 d after disbudding. Tissue type present, wound diameter, and wound depth were evaluated 2 times per week for 7 to 8 wk as measures of wound healing, lying behavior was recorded beginning 1 to 2 wk before disbudding until 7 to 8 wk after as a behavioral indicator of pain, haptoglobin concentrations were measured once per day for 7 d after disbudding, and MNT was evaluated 2 times/wk for 3 wk. Survival analyses were analyzed using Cox regression models (wound healing) and continuous data were analyzed using mixed-effect linear regression models. Only 12% of horn buds were completely healed by 7 to 8 wk after disbudding and 54% had re-epithelized at this time. At any time, wounds from BN calves were more likely to have had re-epithelization occur compared with wounds from LP calves (hazard ratio: 1.93, 95% CI: 1.18-3.14). Wounds from calves that received only one dose of NSAID were more likely to have re-epithelization occur, compared with wounds from calves given 2 doses (hazard ratio: 1.87, 95% CI: 1.15-3.05). Wounds from BN calves had smaller diameters and depths over time beginning on wk 3 compared with LP calves. Wounds from calves that received an additional NSAID had larger diameters and depths over time beginning on wk 4 and 3 respectively, compared with calves that only received one dose of NSAID. Calves that received an extra NSAID tended to be less sensitive 7, 10, and 17 d after disbudding compared with calves that only received one dose and spent less time lying in the week after disbudding. Calves on the BN milk program were more active compared with LP calves with lower lying times, fewer lying bouts per day, and longer average lying bouts. Our results indicate that a BN milk feeding program for calves can result in faster healing times and more activity, and that providing an extra NSAID 3 d after disbudding appears to slow the healing process but may result in less pain experienced by the calf 1 to 2 wk after the procedure. This study is also among the first to demonstrate that after the complete removal of the horn bud, wounds can take more than 8 weeks to re-epithelize and fully heal.

Buffering lidocaine heightens aversion to cornual nerve injections in dairy calves.

Best practice is to numb the horn buds before disbudding dairy calves, which can be achieved by injecting lidocaine, a local anesthetic, around the cornual nerve. In humans, the acute pain that occurs upon injection of lidocaine can be reduced by neutralizing the pH of the solution with an alkalizing agent, such as sodium bicarbonate. We evaluated whether buffering lidocaine would reduce calves' behavioral and physiological responses to cornual nerve blocks on the left and right sides of the head. Female Holstein calves were assigned to 1 of 3 treatments: cornual nerve blocks with 5.5 mL of unbuffered lidocaine (n = 9), buffered lidocaine (n = 9), or a sham procedure with no needle inserted (n = 9). Calves that received either type of lidocaine struggled more during the injection than sham calves. However, contrary to our hypothesis, struggling was most marked in calves that received buffered lidocaine. Similarly, calves administered unbuffered or buffered lidocaine had elevated heart rates for 1 or 3 min after the first injection, respectively, compared with at the end of the 5-min observation period. Calves in the buffered treatment had lower eye temperatures in the first half of the observation period compared with the second half, consistent with responses cattle show to other aversive procedures, but no changes over time were observed in the other 2 treatments. We detected no treatment differences in heart rate variability measures. These results suggest that cornual nerve blocks are aversive, at least in the short term, and that buffering the lidocaine worsens the calf's response to this procedure.

Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.

Dairy calves often perform abnormal repetitive behaviors (ARBs) including tongue rolling and nonnutritive oral manipulation (NNOM) when opportunities to perform feeding behaviors are restricted. Many US dairy farms limit access to milk, a well-studied risk factor for ARBs. However, farms also commonly do not feed forage to young calves, and the motor patterns of oral ARBs resemble those necessary for acquiring and chewing solid feed. Our objective was to assess how access to hay from birth influenced time engaged in normal and abnormal oral behaviors across 24 h. Holstein heifer calves were housed individually on sand bedding and fed ad libitum water and grain (control, n = 11) or given additional access to hay (hay, n = 11) from birth. Calves were fed 5.7 to 8.4 L/d (step-up) of milk replacer via a teat. At the start of step-down weaning (50 ± 1 d), all calves were given access to a total mixed ration. Feed and water intake were measured daily. Oral behaviors (eating, ruminating, sucking milk, drinking water, panting, grooming, tongue flicking, tongue rolling, and NNOM) were recorded by direct observation at wk 2, 4, 6, and 8 using 1-0 sampling at 1-min intervals for 24 h. Grain, hay, and water intake increased over time in the preweaning period. One polydipsic calf regularly consumed >10 L of water/d. During weaning, hay calves tended to consume increasingly more total mixed ration, significantly more water, and less grain than control calves. Access to hay led to more observations spent eating solid feed (7% vs. 5%, mean percentage of intervals) and ruminating (24% vs. 16%) during the preweaning period compared with calves fed only grain, though control calves appeared to ruminate in absence of forage to re-chew. Rumination occurred, to a large extent, overnight. Hay calves also spent less time self-grooming (12% vs. 14%), tongue flicking (14% vs. 18%), and performing NNOM (17% vs. 21%) than control calves. Although NNOM peaked around milk feedings, all 3 behaviors were performed throughout the day. Tongue rolling was rare across treatments, as was panting, which occurred most frequently around 1400 h. There were no behavioral differences during weaning (wk 8). Overall, we found that hay provision affected most oral behaviors that calves perform; it promoted natural feeding behaviors and reduced abnormal ones, suggesting hay should be provided. We also found that calves performed other behaviors, including polydipsia, repetitive grooming, and apparent sham rumination, that may suggest a degree of abnormality in these behaviors that has not been previously identified. These results highlight the importance of considering all oral behaviors to better understand calf welfare.

Validation of 1-0 and instantaneous sampling for quantifying oral behaviors in milk-fed dairy calves.

Oral behaviors, including feeding, drinking, grooming, and non-nutritive behaviors, are used as indicators of health and welfare in dairy calves, but continuous measurement of these behaviors can be labor intensive. Instantaneous sampling is often used to save labor but has only been validated for feeding behavior in calves. One-zero sampling may be an appropriate strategy well suited to capturing the rapid performance of non-nutritive behaviors. Our objective was to validate 1-0 and instantaneous sampling for measurement of oral behaviors around the time of bottle delivery against true values. Eleven Holstein heifer calves were housed individually, provided water, and fed a diet of starter grain and milk replacer (4.8-5.6 L/d step-up) via a bottle. When calves were 23 ± 7 d old, they were video recorded for 30 min before and after the morning 2.5 ± 0.2 L milk meal, from approximately 0900 to 1000 h. We measured ruminating, eating, drinking water, sucking milk, grooming, non-nutritive oral manipulation, and tongue flicks continuously and with instantaneous and 1-0 sampling at 5-, 10-, 30-, and 60-s intervals. We also examined the effect of instantaneous timing within these intervals. Estimates obtained through subsampling were compared with true values via regression analysis. The subsampling interval was determined to represent true values if the coefficient of determination ≥0.9, slope = 1, intercept = 0, and relative error <10%. Ruminating, drinking water, and eating were not performed by all 11 calves and were not included in the analysis. The proportions of time performing non-nutritive oral manipulation, grooming, and tongue flicks generated by continuous and 1-0 sampling were highly correlated but were consistently overestimated by 1-0 sampling, especially as calves spent more time engaged in these behaviors. Sucking milk was accurately represented at intervals of less than 30 s, likely due to most sucking bouts continuing for at least 150 s at a time and low between-calf variability compared with the other behaviors. Different start times within a given instantaneous interval resulted in wide variance in discrepancies between subsampling and continuous recording for all behaviors. We conclude that around milk feeding, 1-0 sampling is an appropriate choice to represent stimulus-elicited behavior, such as sucking milk in a milk-restricted system. However, time engaged in short, highly variable, or intermittent behaviors is not reliably captured via instantaneous or 1-0 sampling in the hour around bottle delivery.

Injury alters motivational trade-offs in calves during the healing period.

Injury can produce long-lasting motivational changes that may alter decisions made under risk. Our objective was to determine whether a routine painful husbandry procedure, hot-iron disbudding, affects how calves trade off risk avoidance against a competing motivation (i.e., feeding), and whether this response depends on time since injury. We used a startle test to evaluate this trade-off in calves disbudded 0 or 21 days previously and non-injured control calves. For 3 days, calves were individually habituated to the testing arena in which they received a 0.5 L milk meal via a rubber teat. On the 4th day, upon approaching the milk reward, the calf was startled by a sudden noise. We assessed the duration and magnitude of the calf's startle response, their latency to return to the milk bottle, and duration spent suckling after startling. No treatment differences were observed in the duration and magnitude of the startle response or in the probability of returning to the bottle after startling. However, among those who did return, disbudded calves spent longer suckling, indicating they accepted more risk in order to feed compared to controls. In addition, calves with 21-day-old injuries tended to return to the bottle faster compared to newly disbudded calves and controls. We suggest that hot-iron disbudding increases calves' motivation to suckle, as they were more likely to prioritize this behaviour over risk avoidance compared to control calves. This effect was most evident 21 days after disbudding, indicating that injury can produce long-term changes in motivational state.

Invited review: Lying time and the welfare of dairy cows.

Adequate time lying down is often considered an important aspect of dairy cow welfare. We examine what is known about cows' motivation to lie down and the consequences for health and other indicators of biological function when this behavior is thwarted. We review the environmental and animal-based factors that affect lying time in the context of animal welfare. Our objective is to review the research into the time that dairy cows spend lying down and to critically examine the evidence for the link with animal welfare. Cows can be highly motivated to lie down. They show rebound lying behavior after periods of forced standing and will sacrifice other activities, such as feeding, to lie down for an adequate amount of time. They will work, by pushing levers or weighted gates, to lie down and show possible indicators of frustration when lying behavior is thwarted. Some evidence suggests that risk of lameness is increased in environments that provide unfavorable conditions for cows to lie down and where cows are forced to stand. Lameness itself can result in longer lying times, whereas mastitis reduces it. Cow-based factors such as reproductive status, age, and milk production influence lying time, but the welfare implications of these differences are unknown. Lower lying times are reported in pasture-based systems, dry lots, and bedded packs (9 h/d) compared with tiestalls and freestalls (10 to 12 h/d) in cross-farm research. Unfavorable conditions, including too few lying stalls for the number of cows, hard or wet lying surfaces, inadequate bedding, stalls that are too small or poorly designed, heat, and rain all reduce lying time. Time constraints, such as feeding or milking, can influence lying time. However, more information is needed about the implications of mediating factors such as the effect of the standing surface (concrete, pasture, or other surfaces) and cow behavior while standing (e.g., being restrained, walking, grazing) to understand the effect of low lying times on animal welfare. Many factors contribute to the difficulty of finding a valid threshold for daily lying time to use in the assessment of animal welfare. Although higher lying times often correspond with cow comfort, and lower lying times are seen in unfavorable conditions, exceptions occur, namely when cows lie down for longer because of disease or when they spend more time standing because of estrus or parturition, or to engage in other behaviors. In conclusion, lying behavior is important to dairy cattle, but caution and a full understanding of the context and the character of the animals in question is needed before drawing firm conclusions about animal welfare from measures of lying time.

The effect of early burn injury on sensitivity to future painful stimuli in dairy heifers.

Animals that experience painful procedures as neonates are more sensitive to pain later in life. We evaluated whether disbudding with a heated iron at 3 (n = 12), 35 (n = 9), or 56 (n = 20) d of age affected heifers' pain responses to vaccine injections at 11 mo of age. Heifers responded to the injection procedure with struggling and changes in eye temperature and heart rate variability compared to a sham procedure the day before, and still had a heightened response 6 d later, regardless of disbudding age. However, some heart rate variability indices suggested increased sympathetic dominance in heifers disbudded at 35 d, compared to the other 2 age groups, independent of the injection procedure. We also found that heifers disbudded at 3 or 35 d had a higher mean heart rate after the injection procedure compared to those disbudded at 56 d. We conclude that: (1) heifers find injections aversive; and (2) there is some evidence that disbudding age influences autonomic nervous system activity later in life.

Behavioral changes in calves 11 days after cautery disbudding: Effect of local anesthesia.

Hot-iron disbudding results in painful burn wounds that take weeks to heal. Spontaneous behaviors indicative of pain are apparent in the immediate hours after disbudding, but whether they occur later in the healing process is unknown. To evaluate whether ongoing pain was present around the time the necrotic tissue loosens from the scalp, we tested the effect of administration of local anesthetic 11 d after the procedure. Disbudded female Holstein and Jersey calves (n = 24) were randomly assigned to receive an injection of local anesthetic (lidocaine) or saline at the cornual nerve on both sides of the head. We recorded the frequency of 8 behaviors for 75 min: head shakes, head rubs, head scratches, ear flicks, tail flicks, bucks/jumps/kicks, grooming, and transitions between standing and lying. Calves treated with lidocaine shook their heads less and tended to flick their ears less than calves administered saline, consistent with the effects of pain relief previously reported in the immediate hours after disbudding. These calves also rubbed their head against the sides of the pen more often, suggesting lidocaine suppressed wound protective behavior. Head shaking and head scratching became more common in the last 25 min compared with the first 50 min in calves treated with lidocaine, consistent with the return of sensation to the disbudding wounds. No treatment differences in the other behaviors were observed. These results suggest that calves experience ongoing pain 11 d after hot-iron disbudding, adding to a growing body of evidence that pain persists for weeks after the procedure.

Sampling strategy and measurement device affect vaginal temperature outcomes in lactating dairy cattle.

Body temperature (BT) is widely used to evaluate health and heat load status in cattle. Despite its importance, studies vary in how BT is measured and in the biological interpretation of the results. Costs, practicality, labor, and welfare concerns can affect how BT is measured, including frequency of measurement and the type of device used. Inaccurate BT outcomes may have implications for cattle welfare; for example, animals may only receive treatment when fever is identified. Our objectives were (1) to compare measurement of vaginal temperature (VT) using relatively small, inexpensive, and low-accuracy loggers (±0.5 to ±1°C, iButton range; Embedded Data Systems, Lawrenceburg, KY) to a high-accuracy logger (±0.1°C; StarOddi, Gardabaer, Iceland), and (2) to evaluate how different BT sampling strategies correspond to 24-h VT in lactating dairy cows. To address the first objective, VT data from 54 cows were recorded every 45 min for 12 d/cow, on average, using 2 different types of temperature loggers (StarOddi DST centi-T and iButton DS1921H or DS1922L) attached to a shortened, hormone-free controlled internal drug release insert. Average VT obtained from both loggers were compared using mixed models and regression analyses. In addition, we tested the consistency of the low-accuracy loggers in detecting cows with elevated BT using the kappa coefficient of concordance. To address the second objective, VT data from 20 cows were recorded every min for 9 to 11 d/cow using StarOddi loggers. Using these data, we estimated average VT using 11 sampling strategies (every 5, 10, 15, 30, 45, 60, and 120 min, 1×/d recorded in the morning or afternoon, 2×/d, or 3×/d). Estimates and observed means were compared using linear regression. Compared with StarOddi loggers, the iButtons either underestimated (H model: 38.7 vs. 38.0 ± 0.06°C) or overestimated VT (L model: 38.7 vs. 39.2 ± 0.04°C). When considering elevated or fever VT thresholds, iButtons did not correctly classify animals; kappa coefficients of concordance were ≤0.35. Measuring VT as often as every 120 min resulted in more accurate estimates compared with strategies that recorded it once to thrice per day. These results indicate that the type of device (i.e., data logger) and sampling strategies affect BT outcomes and that these decisions affect the interpretation of BT data.

Innovative cooling strategies: Dairy cow responses and water and energy use.

Producers in the western United States commonly use spray water at the feed bunk and fans in the lying area to mitigate heat stress in dairy cows. Often, spray water cycles on and off with fans turning on when a preset air temperature is reached. Although this method can be effective, innovative strategies are needed to reduce water and energy use. We evaluated the effectiveness and resource efficiency of 4 cooling treatments on behavioral and physiological responses in dairy cows housed in a freestall barn: (1) conductive cooling in which mats with recirculating evaporatively cooled water were buried under sand bedding (Mat; activated at 18.9°C); (2) targeted convective cooling in which evaporatively cooled air was directed toward the cows through fabric ducts with nozzles at both the feed bunk and lying areas (Targeted Air; activated at 22°C); (3) evaporative cooling, with spray water in the feed area and fan over the freestalls (Baseline; activated at 22°C); and (4) evaporative cooling with half the amount of spray water used in the Baseline and the fan moved to the feed bunk (Optimized Baseline; activated at 22°C). In a crossover design, 8 groups of cows (4/group) producing an average (± standard deviation) of 37.5 ± 4.5 kg/d of milk were tested for 3 d per treatment. For ethical reasons, beginning at 30°C, the Mat treatment was supplemented with Baseline cooling and the Targeted Air treatment had spray water at the Optimized Baseline rate. We recorded body temperature, posture, and location within the pen every 3 min for 24 h/d, and respiration rates every 30 min daily from 1000 to 1900 h. Daily air temperature averaged (±SD) 26.3 ± 7.1°C during 24 h and 33.3 ± 4°C from 1000 to 1900 h. We used pairwise comparisons of each treatment to Baseline to evaluate response variables. Milk production did not differ across treatments, nor did time spent lying (51 ± 2%/d on average). Respiration rates did not differ across treatments overall (61 ± 3 breaths/min), but on an hourly basis, cows in the Mat treatment had a significantly higher rate than those in Baseline, at h 10 and 11 (70 vs. 58-59 breaths/min). Body temperature averaged 38.7 ± 0.05°C across treatments and was 0.2 to 0.3°C higher in the Mat treatment than in Baseline at h 10, 11, 20, 21, and 22. These results collectively indicate that the Mat treatment did not effectively reduce indicators of heat load compared with Baseline. In contrast, Targeted Air and Optimized Baseline were both effective but differed in aspects of efficiency. Targeted Air used the least amount of water but the most energy of all options tested. In conclusion, more efficient heat abatement options were identified, particularly an Optimized Baseline strategy, which cut water use in half, required the same amount of energy as the Baseline, and maintained similar physiological and behavioral responses in cows.

Conditioned place preference reveals ongoing pain in calves 3 weeks after disbudding.

Hot-iron disbudding, a routine procedure that prevents horn bud growth through cauterization, is painful for calves. The resulting burns remain sensitive to touch for weeks, but it is unknown whether calves experience ongoing, non-evoked pain. We evaluated conditioned place preference for analgesia in 44 calves disbudded or sham-disbudded 6 hours (Day 0) or 20 days (Day 20) before testing (n = 11/treatment). Calves were conditioned to associate the effects of a lidocaine cornual nerve block with the location and pattern of a visual stimulus, and a control injection of saline with the contrasting stimulus. On Day 0, disbudded calves tended to prefer the lidocaine-paired stimulus over the saline-paired one, suggesting that they found analgesia rewarding. On Day 20, sham calves avoided the lidocaine-paired stimulus, consistent with humans' experience of this drug being painful. Disbudded calves on Day 20 did not show this aversion, suggesting that they traded off the short-term pain of the lidocaine with the longer-term analgesia provided. Day 0 sham calves did not avoid the lidocaine-paired stimulus, likely because they received less than half the dose of Day 20 calves during conditioning. Thus, higher doses of lidocaine are aversive to uninjured animals, but disbudded calves are willing to engage in this cost. We conclude that calves experience ongoing pain 3 weeks after disbudding, raising additional welfare concerns about this procedure.