Short communication: Temporal profiles of colostrum and milk haptoglobin and substance P in early lactation multiparous Holstein cows

Milk markers have the potential to aid in the detection of cow disease in early lactation if the automation of milk analysis becomes commonplace. Characterising temporal profiles of milk markers in dairy cows will improve the understanding of basal concentrations in clinically healthy cows. The objective of this observational study was to characterise the variation and temporal profiles of colostrum and milk haptoglobin (Hp) and substance P concentrations within 21 days postcalving in clinically healthy multiparous Holstein dairy cows. Ninety Holstein dairy cows from a commercial dairy herd were included. Milk samples were collected on the day of calving (day 0), and on days 1 to 4, 7, 14, and 21 postcalving and concentrations of Hp and substance P in colostrum (days 0 to 3) and milk (days 4, 7, 14, and 21) were determined using Enzyme Linked Immunosorbent assay. Haptoglobin and substance P concentrations were, on average (raw means ± SD), 0.40 ± 0.26 µg/ml and 56.2 ± 38.7 pg/ml in colostrum, respectively, and 0.23 ± 0.23 µg/ml and 37.1 ± 27.8 pg/ml in milk, respectively. Haptoglobin and substance P were elevated and greatest 1 day postcalving (least squares mean ± SE of the mean; 0.53 ± 0.05 µg/ml and 46.5 ± 3.64 pg/ml, respectively) and substance P varied widely within 21 days postcalving. The presence of substance P in dairy cow colostrum was not documented previously. Elevated concentrations of Hp and substance P immediately postcalving may be due to physiological roles these inflammatory markers have in the dairy cow or neonate or may simply represent an accumulation in colostrum before the first milk is removed.

Animal- and herd-level factors associated with onset of puberty in grazing dairy heifers

AIMS

To explore animal- and herd-level risk factors influencing age at puberty in predominantly Holstein-Friesian dairy heifers managed in seasonal, pasture-based systems.

METHODS

Heifers born in spring 2018 (n = 5,010) from 54 commercial dairy herds in New Zealand were visited on three occasions when the mean heifer age, within herd, was 10 (visit 1; V1), 11 (V2) and 12 (V3) months old. Blood samples were collected on each visit and liveweight, stature and anogenital distance (AGD) were measured at V2. Heifers were defined as having reached puberty at the first visit where blood progesterone was elevated (≥ 1 ng/mL). Animal-level response variables included pubertal status by V1, V2 and V3, and age at puberty (or age at V3 plus 31 days for those that had not attained puberty by V3). To explore herd-level management factors, farmers answered a questionnaire relating to animal location, land type, health, feeding, and management between weaning and mating. A partial least squares regression was undertaken to identify herd-level factors associated with the greatest influence on puberty rate within herd.

RESULTS

The mean age at puberty was 352 (SD 34.9) days. Heavier animals at a greater proportion of expected mature liveweight based on their breeding value for liveweight, or animals with a higher breed proportion of Jersey and lower breed proportion of Holstein, were associated with earlier puberty. Herd puberty rates varied widely among enrolled herds, and averaged 20%, 39% and 56% by V1, V2 and V3, respectively. Liveweight, followed by breed and land type, had the greatest influence on the herd puberty rate. Heifer herds with a greater mean liveweight (absolute and proportion of expected mature weight) or greater Jersey proportion had more animals that reached puberty at any visit, whereas herds located on steep land or with greater Holstein breed proportions had lower puberty rates. Management-related factors such as vaccinations, provision of feed supplements, and weighing frequency were also herd-level risk factors of puberty but had less influence.

CONCLUSIONS AND CLINICAL RELEVANCE

This study highlights the importance of having well-grown heifers for increasing the chances of earlier puberty onset and the effect of breed and youngstock management to achieve growth targets. These outcomes have important implications for the optimal management of heifers to achieve puberty before their maiden breeding and for the timing of measurements to potentially incorporate a puberty trait in genetic evaluations.

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.

Effect of weather on activity and lying behaviour in clinically healthy grazing dairy cows during the transition period

Lying behaviour and activity were measured in healthy grazing dairy cows during the transition from late gestation to early lactation (i.e. the transition period). Behaviour data derived from IceTag® or IceQube® (IceRobotics, Edinburgh, Scotland, UK) tri-axial accelerometers were collated from 311 cow parities of mixed age and breed (Holstein–Friesian, Jersey and crossbred Holstein–Friesian × Jersey) cows from four experiments. The IceTag and IceQube devices captured lying and step data at 1- and 15-min intervals respectively. Behaviour was recorded during the transition period (Day –21 prepartum to Day 34 postpartum) to determine daily lying time, number of lying bouts (LB), mean LB duration and number of steps. The effect of rainfall and air temperature on lying behaviour and activity during two periods, namely, prepartum (Day –21 to Day –3) and postpartum (Days 3–34) was evaluated. Multiple-regression analysis determined that decreased air temperature and increased rainfall is associated with a decline in daily lying time, number of LB and LB duration during both prepartum and postpartum periods. Exposure to both wet and cold conditions exacerbated the behavioural response. The results highlighted the importance of considering the effects of air temperature and rainfall and the interaction of these two climate variables when analysing lying behaviour and activity. Further work is required to quantify the trigger points for this activity modulation, to help understand the balance of welfare experiences in the life of a grazing cow.

Selenium requirements in grazing dairy cows: a review

In New Zealand, the recommended intake of Se for dairy cattle (0.03 mg/kg dry matter (DM)) is lower than in the United Kingdom and Australia (0.1 and 0.04 mg/kg DM, respectively), and much lower than in the United States of America (0.3 mg/kg DM). Advisors in New Zealand often suggest that New Zealand intake recommendations are far too low and that recommendations from the United States of America should be used. This has created confusion as farmers are given very different advice depending on which recommendations their advisor uses. In this review, we assess whether the published evidence supports the existing dietary requirements and associated Se status thresholds, or if change is required. We focus particularly on the evidence-base in cattle fed a primarily pasture-based diet, as it is critical that dietary recommendations are derived from data created using cows fed similar diets. Accordingly, we also consider whether the increased use of fodder crops, especially during the dry period, is likely to have altered the Se requirements of dairy cows in New Zealand. We report that the science behind the dietary requirements for Se is robust, being supported by factorial models validated using New Zealand data, and on-farm experimental studies. Published nutritional data suggest that the increased use of fodder crops is unlikely to have altered the dietary balance of pro- and antioxidant factors in New Zealand dairy cows in a way that would meaningfully affect Se requirements. However, the lack of specific data on the vitamin E and fatty acid content of the crops being fed in New Zealand means that more information is needed to confirm this conclusion. In general, the existing New Zealand recommendations for Se-status thresholds are supported, although studies are still lacking to properly characterise the upper threshold of the marginal range. Nevertheless many studies in New Zealand, of herds with marginal or low adequate Se status (using New Zealand recommendations), have failed to show an effect of Se supplementation on milk production, intramammary infection or reproductive performance, so it is highly unlikely that the upper threshold of the range is much higher than the current recommendation. Proponents of the hypothesis that Se intakes in New Zealand dairy cattle should be increased by at least 10 times the current recommendations are therefore not using the evidence base correctly.

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.