Effect of glycerol supplementation in early lactation on metabolic health, milking activity, and production of dairy cows in automated milking system herds

The objective of this study was to quantify the effects of supplementing early-lactation cows with a dry pure glycerol product, delivered through the automated milking system (AMS) concentrate, in the first 21 d in milk (DIM) on metabolic markers, milking behavior, and milk production. In 5 commercial AMS dairy herds, 389 dairy cows were randomly assigned, controlling for parity, 21 d before expected calving to 1 of 2 treatments, within farm: (1) control group (CON) receiving the standard AMS pellet (n = 213) from 1 to 150 DIM, or (2) glycerol group (GLY) receiving the treatment AMS pellet (n = 176) formulated to deliver 250 as fed g/d of glycerol product from 1 to 21 DIM (mean actual = 249 g/d dry matter [DM]), then they received the standard AMS pellet from 22 to 150 DIM. Across all farms, cows were fed partial mixed rations (PMR) that were similar in ingredient and nutrient composition. One prepartum blood sample and 5 postpartum blood samples were collected from each cow to determine serum nonesterified fatty acids (NEFA), blood β-hydroxy butyrate (BHB), and blood glucose concentrations. Cow body condition score (BCS) was recorded every 21 d from -21 to 63 DIM. Data were collected and analyzed for the treatment period (1 to 21 DIM) and a follow-up period (22 to 150 DIM). There was no detected treatment effect on serum NEFA concentrations in the first week of lactation. There was a treatment by time interaction for blood BHB and blood glucose, where GLY cows tended to have increased BHB concentrations at 5 DIM and had decreased glucose concentrations at 9 and 12 DIM. There was an interaction of BCS with treatment on the incidence of BHB ≥1.2 mmol/L, whereby over-conditioned CON cows (BCS ≥3.5) were 3.5x more likely to have a high BHB test than CON cows with normal prepartum BCS. During the treatment period GLY cows had 0.1 ± 0.05 more successful milkings/d, were delivered 0.27 ± 0.05 DM kg/d more AMS concentrate and tended to yield 0.8 ± 0.47 kg/d more milk. During the follow-up period GLY cows had 0.1 ± 0.04 more successful milkings/d, were delivered 0.18 ± 0.06 DM kg/d more AMS concentrate, and yielded 1.5 ± 0.53 kg/d more milk than CON cows. Glycerol supplementation allowed cows to maintain better BCS, as GLY cows lost less BCS from calving to 63 DIM than CON cows. Overall, the results of this study demonstrate that supplementing pure glycerol through the AMS concentrate for the first 21 DIM can reduce BCS loss in early lactation, improve milking behavior, and increase milk yield to mid lactation.

Association between genomic daughter pregnancy rate and expected milk production on the resumption of estrus behavior in Holstein cattle

The objective of this observational study was to evaluate estrous expression at the first estrus occurring between 7 to 30 d in milk (DIM), as detected by an automated activity monitor (AAM), and its association with genomic daughter pregnancy rate (GDPR) and genomic expected milk production (GEM) in lactating dairy cows. A total of 4,119 lactations from 2,602 Holstein cows were included. Cows were enrolled as first lactation (n = 1,168), second lactation (n = 1,525) and third and greater lactation (n = 1,426). Hair samples were collected from the tail switch, and cows were genotyped using an SNP platform (Clarifide, Zoetis, São Paulo, SP, Brazil). Postpartum cows were examined daily by the farm personnel from calving until 10 DIM. Calving was classified as assisted (forced calf extraction) and unassisted (normal calving). Retained fetal membranes (RFM), hyperketonemia (KET), and left displaced abomasum (LDA) were also recorded. Mean GDPR (± SD) was -0.29 ± 1.4, and the intensity and duration of the first estrus event was 15.9 ± 13.1 x-factor (intensity unit measurement) and 11.1 ± 3.8 h, respectively. Cows that had greater GDPR had greater intensity and longer duration of estrus at the alert, independent of parity. Overall resumption of estrous expression, between 7 to 30 DIM, was 41.2% (1,695/4,119), where 58.8% (2,424/4,119) did not have an estrus event, 31.0% (1,274/4,119) of cows had one event of estrus, and 10.2% (421/4,119) of cows had 2 or more events of estrus early postpartum. Mean DIM (± SD) at first estrus event, detected by the AAM, was 19.4 ± 4.4 d. Days in milk at first event for cows with one event was 20.7 ± 1.6 d and 15.9 ± 3.1 d for cows with 2 or more events of estrus. First lactation cows were more likely to have an estrus event early postpartum when compared with second and third and greater lactation cows (45.2 ± 1.4% [530/1168] vs. 41.6 ± 1.3% [636/1525] vs. 37.2 ± 1.3% [529/1426], respectively). There was an interaction of parity and GDPR on the proportion of cows demonstrating an early postpartum estrus. There was no difference in the proportion of cows with an early postpartum estrus between those with assisted or unassisted calving, RFM, or LDA. However, cows that had KET were less likely to have an alert early postpartum when compared with cows that did not have KET. Mean genomic expected milk production (± SD) was 256.8 ± 600.1 kg. There was no interaction between GEM and parity on estrous expression (i.e., intensity and duration). There was no interaction between GEM and GDPR on the proportion of estrus early postpartum.

Comparison of Two Methods for the Measurement of Blood Plasma and Capillary Blood Glucose in Tropical Highland Grassing Dairy Cows

(1) Background: There is lack of published studies validating specific cow-side glucometers such as Centrivet GK (CVGK). (2) Methods: The aims were (1) to measure and compare the blood glucose concentrations in 52 tropic highland grassing cows by using CVGK and the traditional enzymatic/photometric assay (EPA) in plasma and serum (reference method) and (2) to establish if glucose concentrations obtained via these methods could be affected by several demographic and zootechnical parameters of the dairy herd evaluated. (3) Results: Glucose concentrations were significantly (p = 0.00) affected by the method used for their measurement. The intra-assay coefficient of variation (CV) for glucose concentrations in plasma EPA and for CVGK was 14% for both methods with serum EPA, whereas the inter-assay CV for plasma EPA and CVGK was 8% and 13.7%, respectively, with serum EPA. Pearson correlation coefficient calculations between the reference method in serum and plasma presented a slightly positive significant (p = <0.000) correlation (r = 0.56), whereas there was not a significant (p = 0.413) correlation between serum EPA and CVGK (r = 0.135). The Passing and Bablok regressions were out of the ideal expected values for the slope (β = 1) and the intercept (α = 0) (11), whereas the Bland-Altman plots showed a bias of 5.29 ± 11.73 (mg/dL) for serum and plasma and 11.01 ± 15.74 (mg/dL) for serum and CVGK. The ROC curve showed no sensitivity in detecting normoglycemic cows (area = 53.7 %, e.d = 12.5 %, p = 0.759) for CVGK when compared to plasma EPA (area = 36.1 %, e.d = 14.2 %, p = 0.256). Plasma EPA exhibited a better but not significant effect in detecting hyperglycemic cows (area = 63.9%, e.d = 14.2%, p = 0.256) when compared to HHD (area = 46.3 %, e.d = 12.5 %, p = 0.759). General glucose concentrations, independently of the method used, were significantly (p = <0.001) greater in young cows when compared to adult and old cows. (4) Conclusions: Glucose concentration measurement in plasma by using EPA or in capillary blood via CVGK were not reliable methods when compared with the reference method.

Effect of pre- and postpartum supplementation of a pure glycerol product to dairy cows on feed intake, metabolic markers, and milk yield and components

The objective of this study was to quantify the effects of supplementing transition dairy cows with a low inclusion dry glycerol product in the pre- and postpartum periods on feed intake, metabolic markers, and milk yield and components. Multiparous Holstein dairy cows (n = 60) were enrolled in a 2-by-2 factorial design study. Starting 21 d before expected parturition, cows individually received a dry cow diet with (1) 250 g/d glycerol product supplementation [66% pure glycerol (United States Pharmacopeia grade); GLY], or (2) no supplementation (CON) mixed to their total mixed ration. After parturition, cows, again, were individually assigned to either GLY, or (2) no supplementation (CON) to their partial mixed ration for the first 21 d in milk (DIM). Cows were milked by an automated milking system and offered a target of 5.4 kg DM/d pellet (23% of target total dry matter intake, DMI) in the automated milking system and followed for 42 d into lactation. Blood samples were collected 6.3 ± 3.47 d before calving for all blood measures and 3, 7, 10, and 14 DIM for analysis of glucose and β-hydroxybutyrate, as well as 3 and 7 DIM for nonesterified fatty acids (NEFA) and haptoglobin. Initial dry cow body weight (BW), calf birth weight, previous 305-d milk, and month of parturition were used as covariates in the statistical model. Cows supplemented with GLY prepartum lost less BW and consumed more DMI pre- and postpartum, as well as had lower postpartum blood β-hydroxybutyrate and NEFA concentrations compared with those fed the CON treatment prepartum. Cows supplemented with GLY postpartum had lesser DMI in the first 42 DIM than cows fed CON postpartum, but also had reduced blood NEFA concentrations, odds of a high haptoglobin test, odds of a low blood glucose test, and lesser preformed fatty acid concentrations and yields in their milk. Cows supplemented glycerol both pre- and postpartum lost the least total BW from -21 to 21 DIM. No treatment effects were detected for milk yield; however, cows receiving GLY postpartum had lower milk fat. Overall, glycerol supplementation during the transition period, particularly during the 21 d before calving, was associated with markers of improved metabolic status.

Hyperketonemia: A Marker of Disease, a Sign of a High-Producing Dairy Cow, or Both?

This review covers the history and nomenclature of ketosis, the source and use of ketones in transition cows, and the controversial role of hyperketonemia's association with health and production outcomes in dairy cows. With the goal of assisting veterinarians with on-farm diagnostic and treatment methods, the authors present current and evolving means of direct and indirect hyperketonemia detection as well as a summary of treatment modalities and their efficacy. They encourage veterinarians to include hyperketonemia testing as part of their routine physical examinations and contemplate day in milk at hyperketonemia diagnosis when designing treatment and management strategies.

Accuracy of Subclinical Ketosis Detection with Rapid Test Methods for BHBA in Blood in Commercial Dairy Farms

This study gives an overview of the performance and accuracy of devices used for the fast measurement of β-hydroxybutyrate (BHBA) in blood for the on-farm indication of subclinical ketosis. Data were collected on ten dairy farms. In each farm, blood samples were taken from ten cows on four test days (2, 4, 9 and 11), resulting in 400 samples. The reference method was the BHBA concentration in blood serum (BHBALAB). Four different devices that measure BHBA in whole blood were tested. The thresholds applied for identifying subclinical ketosis were ≥1.0, ≥1.2 and ≥1.4 mmol/L in blood serum. The BHBALAB was assigned in three classes: low—≤0.9 mmol/L; high—>0.9 mmol/L; and total—all values unclassified. Due to initial negative effects on the health and performance of cows with BHBA levels ≥0.9 mmol/L, this cut-off was chosen. The Passing–Bablok regression revealed different constant as well as absolute biases for each device in the aforementioned classes. The area under the receiver operating characteristics curve indicated highly accurate results, with 94–97% accuracy levels. As an overall conclusion, the performance of the devices was good and supports their use by farmers for the detection of subclinical ketotic cows in their herds.

Performance evaluation of a newly designed on-farm blood testing system for determining blood non-esterified fatty acid and β-hydroxybutyrate concentrations in dairy cows

The objective of this study was to evaluate a newly designed on-farm blood testing system (OFBTS) for monitoring blood concentrations of non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHBA) in dairy cows. Blood samples from 230 Holstein dairy cows between -86 and 343 days in milk were collected. A drop of whole blood was used to determine NEFA and BHBA using the OFBTS. Plasma from the remaining blood was used to determine both analytes using a commercial kit (gold standard). In the repeatability of the OFBTS, the intra-assay CV for NEFA and BHBA were 1.3% and 4.5%, and the inter-assay CV were 1.8% and 2.9%, respectively. The slope and coefficient of determination of OFBTS analysis of NEFA compared to the gold standard were 0.92 and 0.94. Those for BHBA were 0.94 and 0.98. Mean of the difference between the gold standard laboratory assays and OFBTS of NEFA and BHBA were 0.021 and 0.019, respectively. However, the bias became substantial for NEFA in the higher concentration ranges (>1.2 mEq/L). The sensitivity and specificity of NEFA were 93.2% and 99.4% at a cutpoint of 0.4 mEq/L, and 87.9% and 100% at 0.6 mEq/L. Those of BHBA were 86.2% and 99.0% at a cutpoint of 1.0 mM, and 94.7% and 99.5% at 1.2 mM. The reaction time for the NEFA to reach 0.6 mEq/L was 7 min. The BHBA reaction reached 1.2 mM within 2 min. In conclusion, the OFBTS has excellent performance for evaluating blood NEFA or BHBA concentrations.

Behavior, health, and productivity of early-lactation dairy cows supplemented with molasses in automated milking systems

The objective of this study was to determine the effect of molasses-based liquid feed (LF) supplementation within automated milking systems (AMS) on the behavior, health, and production of early-lactation dairy cows. In 6 commercial AMS dairy herds, 390 dairy cows were randomly assigned before calving to 1 of 2 treatments, within farm, balanced by parity: (1) control group (CON) receiving a standard AMS pellet [mean = 3.9 kg/d on a dry matter (DM) basis, n = 188], or (2) same amount of standard AMS pellet (mean = 3.6 kg/d on a DM basis, n = 202) plus 1 kg/d DM of LF for multiparous cows (1.6 kg/d as fed) and 0.88 kg/d DM for primiparous cows (1.4 kg/d as fed). Across farms, cows were fed partial mixed rations similar in ingredient and nutrient composition. Cows on the LF treatment received supplementation for the first 60 d in milk (DIM). Blood samples were taken 2 times/wk for the first 3 wk postcalving to assess β-hydroxybutyrate (BHB). Samples with BHB ≥1.2 mmol/L were classified as a positive case of subclinical ketosis (SCK). Cow body condition and lameness were scored every 10 d postcalving until 60 DIM. No differences were detected between treatments for milk yield (average milk yield = 37.4 ± 1.98 kg/d) and milking frequency (average milking frequency = 3.2 ± 0.01 times/d). Similarly, no difference between treatments in daily AMS visits was detected (average AMS visits = 5.3 ± 0.3 times/d). However, CON cows experienced more AMS refusals/d than LF cows (LF = 1.6 refusals/d, CON = 2.1 refusals/d). No difference between treatments in daily rumination time was detected (average rumination time = 476 ± 10.8 min/d). Treatment was associated with the number of times cows tested positive for SCK; cows on LF had fewer repeated diagnoses of SCK, such that 15% of cows on LF had ≥3 diagnoses of SCK out of 5 tests, compared with 27% of CON cows. Cows receiving molasses tended to have lower blood BHB values at ∼15 DIM. Molasses supplementation also allowed cows to maintain a more stable body condition score, as LF cows tended to lose less body condition over the first 60 DIM compared with CON cows. Overall, the results of this study demonstrate that supplementing a molasses-based LF to AMS cows may help support the energy demands of milk production in early lactation and, thus, reduce the incidence of repeat positive SCK tests during that time period.

Effect of diet-induced negative energy balance on the feeding behavior of dairy cows

The objective of this study was to determine how feeding behavior of dairy cows is altered in response to diet-induced negative energy balance, and if this response varies depending on dietary particle size distribution. Multiparous Holstein cows (n = 30; days in milk = 59 ± 5; parity = 2.8 ± 0.19), producing 44.6 ± 1.2 kg/d of milk, were fed (on a dry matter basis) a lactating diet [net energy of lactation (NE_L) = 1.66 Mcal/kg; 68% forage, including 1.8% wheat straw] during a 2-wk baseline period. To induce negative energy balance, cows were then exposed for 3 wk to 1 of 2 diets formulated for a 20% reduction in energy available for milk (NE_L = 1.58 Mcal/kg; 73% forage, including 17.2% wheat straw). These diets were identical, only varying in straw chop length: (1) long straw diet (LS): straw chopped with a 10.2-cm screen, or (2) short straw diet (SS): straw chopped with a 2.54-cm screen. Cows consumed 25.6 ± 0.26 kg/d during the baseline period. Dry matter intake decreased on the experimental diets; dry matter intake was greater for the SS diet as compared with the LS diet (23.1 vs. 22.5 kg/d; standard error = 0.47). During the baseline period, cow serum nonesterified fatty acids (NEFA) and blood β-hydroxybutyrate averaged 0.27 ± 0.02 and 0.71 ± 0.05 mmol/L, respectively. During the experimental period, NEFA and β-hydroxybutyrate averaged 0.34 and 1.04 mmol/L, respectively, with a peak of NEFA (0.63 ± 0.06 mmol/L) occurring 4 d after dietary change. During baseline, cows produced 42.3 ± 0.33 kg/d of milk; milk yield was decreased for both SS cows and LS cows during the experimental period (SS = 39.0, LS = 37.8 kg/d; standard error = 0.67). On the experimental diets, cows spent more time eating (266.8 vs. 221.8 min/d), had longer meal lengths (46.9 vs. 37.5 min/meal), and consumed fewer meals (7.1 vs. 7.7 meals/d) compared with the baseline period. Within the experimental period, LS cows spent more time eating per day than SS cows (LS = 281.3, SS = 252.2 min/d). During the baseline period cows sorted against long particles (>19 mm), did not sort medium particles (8 to 19 mm), and sorted for short (4 to 8 mm) and fine (<4 mm) particles. Cows did not change sorting of long particles on the SS diet, but increased sorting against these on the LS diet. On the SS diet cows did not change their sorting of short and fine particles. On the LS diet cows increased sorting for short and fine particles. In the baseline period, no association was detected between feed sorting and serum NEFA concentration. During the experimental period, greater NEFA concentration was associated with greater sorting in favor of short particles for both the LS and SS diets. Furthermore, greater NEFA concentration was associated with greater sorting against the longest particles for both the LS and SS diets. No associations of blood and meal variables were detected during the experimental period. Overall, cows altered their feed sorting behavior in response to experiencing a diet-induced period of negative energy balance and the severity of negative energy balance was associated with the extent of that change in feed sorting.

Effects of molasses-based liquid feed supplementation to a high-straw dry cow diet on feed intake, health, and performance of dairy cows across the transition period

The objective of this study was to determine the effects of adding molasses-based liquid feed to a high-straw dry cow diet on intake, behavior, health, and performance of dairy cows across the transition period. Holstein cows (n = 40) entering their second lactation or greater were enrolled at dry-off (∼45 d before expected calving) and assigned to 1 of 2 treatments: a high-straw dry cow total mixed ration (TMR) with either (1) no molasses [CON; n = 20; 10.7% crude protein (CP), 1.45 Mcal/kg of net energy for lactation (NE_L)] or (2) supplemented with 1 kg/cow daily [dry matter (DM) basis] of molasses-based liquid feed (LF; n = 20; 11.2% CP, 1.49 Mcal/kg of NE_L). At calving all cows were fed the same lactating TMR (14.9% CP, 1.68 Mcal/kg of NE_L) and followed for 28 d. During the dry period, cows fed the LF diet had greater DM intake (15.3 ± 0.24 vs. 13.4 ± 0.24 kg/d) and tended to have a shorter interval between meals (192.8 ± 8.38 vs. 216.5 ± 7.97 min) and more frequent meals (6.3 ± 0.27 vs. 5.6 ± 0.27 meals/d), while consuming their feed faster (0.09 ± 0.001 vs. 0.08 ± 0.001 kg of DM/min) compared with cows fed the CON diet. Regardless of treatment, cows sorted [100% × (actual intake/predicted intake)] against the longest ration particles (>19 mm), with cows fed the CON diet sorting more against these (81.1 ± 2.6 vs. 93.9 ± 2.6%). Cows fed the CON diet did not sort for or against short particles (<8, >4 mm; 100.2 ± 0.31%), but cows fed the LF diet tended to sort against these (99.2 ± 0.31%). Post-calving, cows fed the LF diet did not sort for long particles (98.5 ± 1.1%), but cows fed the CON diet continued to sort against these (96.3 ± 1.1%). Cows fed the LF diet had higher mean reticulorumen pH in the dry period (6.4 ± 0.05 vs. 6.2 ± 0.06 pH), in the first week after calving (CON = 5.7 ± 0.06 pH, LF = 5.8 ± 0.06 pH), and tended to have higher mean reticulorumen pH in the second week after calving (CON = 5.7 ± 0.06 pH, LF = 5.9 ± 0.06 pH). The results suggest that supplementing a molasses-based liquid feed in high-straw dry cow diets may improve intake and consistency in nutrients consumed during the dry period and in early lactation, as well as possibly promoting better rumen health across the transition period.

Effect of wheat- or oat-straw inclusion with wheat bran or corn grain in prepartum diets on postpartum performance of transition dairy cows

Current study evaluated the effects of feeding straw source and energy supplementation during prepartum period on postpartum production performance and changes in blood metabolites of crossbred dairy cows. Twenty-eight crossbred (Holstein × Sahiwal) cows were randomly assigned to one of the following four dietary treatments: (1) wheat straw and corn grain (WSCG), (2) wheat straw and wheat bran (WSWB), (3) oat straw and corn grain (OSCG) and (4) oat straw and wheat bran (OSWB) in a 2 × 2 factorial experiment. Iso-nitrogenous diets fed as ad libitum total mixed ration contained 25% wheat straw (WS) or oat straw (OS) and 10% corn grain (CG) or wheat bran (WB). Experimental duration was 42 days before and 56 days after calving. After calving, all animals were fed a similar lactation diet. Pre- and postpartum dry-matter intake % of BW was not affected by treatments. Prepartum energy balance (EBAL) was higher for OS than WS and higher for CG than WB animals. Postpartum EBAL was higher in the WSCG than OSCG treatment. Milk production and composition were not affected by straw source or energy concentrate. Milk yield at Weeks 1, 2 and 3 was higher in the WSWB than WSCG and OSWB treatments. Total solids and feed efficiency were higher in the WSWB than WSCG treatment. Postpartum plasma concentration of non-esterified fatty acids was higher in the WS than the OS diet; however, the measured values were within normal limits. Postpartum plasma β-hydroxybutyrate concentration was not affected by straw source or energy concentrate. Cows fed WSWB prepartum were in positive EBAL, before and after calving, closer to the recommended requirements. Moreover, cows fed WSWB had a lower incidence of health disorders and subclinical ketosis, higher milk production and better feed conversion efficiency during first 3 weeks after calving.

Moisture content of high-straw dry cow diets affects intake, health, and performance of transition dairy cows

The objective of this study was to determine the effect of adding water to a high-straw dry cow diet on feeding behavior, health, and performance of dairy cows. Holstein cows (n = 40) entering their second or greater lactation were enrolled at dry off (∼45 d before expected calving) and assigned to 1 of 2 dietary treatments, consisting of a high-straw dry cow total mixed ration [TMR; 36% wheat straw, 41% corn silage, 23% pellet, on a dry matter (DM) basis, formulated for 11.6% crude protein, 1.35 Mcal/kg net energy for lactation] with (1) no water (CON; n = 20; DM = 53.4%) or (2) water added to decrease the DM by ∼10 percentage points (wet diet, WD; n = 20; DM = 45.4%). Upon calving, all cows were fed the same lactating TMR (45.2% DM, 14.9% crude protein, 1.68 Mcal/kg net energy for lactation) and followed for 28 d. Dry matter intake, feeding behavior, and rumination activity were recorded automatically. Fresh TMR and orts samples were collected 2×/wk to determine differences in sorting. A particle separator was used to separate feed samples into 4 fractions: long (>19 mm), medium (<19, >8 mm), short (<8, >4 mm), and fine (<4 mm) particles. Feed sorting was calculated as actual intake of each particle fraction expressed as a % of predicted intake. Cows fed WD had greater DM intake during the dry period than cows fed CON (CON = 13.4 ± 0.24, WD = 14.2 ± 0.24 kg/d), but rumination did not differ (CON = 522.2 ± 8.48, WD = 518.5 ± 8.69 min/d) between treatments. Cows fed WD tended to consume their feed faster (CON = 0.08 ± 0.001, WD = 0.09 ± 0.001 kg of DM/min) compared with CON cows. Regardless of treatment, cows sorted against the longest ration particles, with cows fed CON sorting more against these (CON = 81.1 ± 2.51%, WD = 94.9 ± 2.58%). Cows fed CON tended to sort more in favor of the medium particles than those fed WD (CON = 105.0 ± 0.36%, WD = 104.2 ± 0.37%). Postcalving DM intake and feeding behavior were not affected by dry diet treatment. Cows fed WD experienced a less rapid daily decline in rumen pH during the first 7 d after calving compared with those fed the CON diet. The results suggest that increasing the moisture content of high-straw dry cow diets, by adding water, may improve intake and reduce sorting against the longest ration particles, which may help promote consistency in targeted nutrients consumed during the dry period and greater rumen health in early lactation.

Technical note: Glucose concentration in dairy cows measured using 6 handheld meters designed for human use

The objective was to evaluate the precision and accuracy of 6 handheld glucose meters, designed for human use [Accu-Chek Aviva Plus (AC), Roche Diabetes Care, Mannheim, Germany; Aga Matrix (AM), AgaMatrix Inc., Salem, NH; Contour Next (CT), Bayer HealthCare LLC, Leverkusen, Germany; FreeStyle Precision Neo (FS), Abbott Diabetes Care Ltd., Alameda, CA; Nova Max Plus (NM), Nova Biomedical Corporation, Waltham, MA; and Precision Xtra (PX), Abbott Diabetes Care Ltd., Witney, UK] to measure blood glucose concentration in dairy cows. Blood samples from Jersey and Jersey × Holstein crossbreed cows (n = 97 for all; except CT, n = 71) were collected and analyzed in triplicate using the 6 handheld glucose meters evaluated. Plasma glucose was also measured with the laboratory reference method (hexokinase glucose-6-phosphate dehydrogenase). Based on the intra-assay coefficient of variation (CV), precision varied across handheld glucose meters: AC (2.2%), CT (4.0%), PX (4.7%), FS (5.6%), AM (6.2%), and NM (6.7%). Lin's concordance correlation coefficients between handheld glucose meters and the reference method were 0.75 for FS, 0.74 for PX, 0.62 for AC, 0.55 for CT, 0.53 for NM, and 0.48 for AM. Based on Passing-Bablok regression, the AM and PX meters showed bias in the measurements of blood glucose. Bland-Altman plots indicated a negative bias (FS = -0.25 mmol/L; CT = -0.60 mmol/L) or a positive bias (AM = 0.29 mmol/L; PX = 0.33 mmol/L; NM = 0.52 mmol/L; AC = 0.65 mmol/L) between handheld glucose meters and the reference method. All handheld glucose meters evaluated had wide limits of agreement (LoA) ranging from -0.18 to 1.47 mmol/L (AC, narrowest LoA) to -1.25 to 1.82 mmol/L (AM, widest LoA). Bias was the major contributor to the total observed error (TE_obs), accounting for 81.5% of the TE_obs in AC, 72.0% in CT, 64.9% in AM, 61.1% in NM, 57.8% in PX, and 56.2% in FS. Overall, although some handheld meters (AC, CT, and PX) showed satisfactory precision, none were accurate measuring glucose. Future studies should evaluate whether incorporating algorithms designed for cattle can improve accuracy and precision of handheld glucose meters.

Short communication: Assessing the accuracy of inline milk fat-to-protein ratio data as an indicator of hyperketonemia in dairy cows in herds with automated milking systems

The objective of this study was to evaluate the accuracy of inline milk fat-to-protein (F:P) data to detect hyperketonemia (HYK) in herds with automated milking systems (AMS). The F:P ratio has been investigated as a tool for detecting HYK with moderate accuracy in past studies, but inline F:P data in AMS may also be useful for HYK screening. To assess the accuracy of these data in commercial settings, we monitored 484 cows from 9 AMS herds for their first 3 wk of lactation, taking blood samples once per week (n = 1,427). Positive cases of HYK were defined by whole-blood β-hydroxybutyrate (BHB) concentrations ≥1.2 or ≥1.4 mmol/L. Milk data were collected from the AMS software on each farm for each cow and converted into 4 different F:P values: (1) value from the same day as the BHB test; (2) 5-d centered-moving average (CMA); (3) 5-d backward-moving average (BMA); (4) 5-d forward-moving average (FMA). In linear regression models, all 4 values were associated with BHB, but slope estimates varied and R² were low: same day (slope = 0.95, R² = 0.07), CMA (slope = 1.05, R² = 0.07), BMA (slope = 0.65, R² = 0.04), and FMA (slope = 1.23, R² = 0.09). In logistic regression models, the odds of having HYK (BHB ≥1.2 mmol/L) increased with every 0.1-unit increase from the mean F:P ratio (1.16) using same-day values (odds ratio = 1.35, 95% confidence interval = 1.25-1.47) and CMA (odds ratio = 1.39, 95% confidence interval = 1.27-1.51). The same increase in F:P from mean BMA (1.14) and FMA (1.17) was associated with 1.22 and 1.49 times the odds of HYK, respectively. For all 4 F:P variations, we evaluated the sensitivity, specificity, positive predictive value, and negative predictive value of different F:P thresholds with HYK status. As the F:P threshold increased from 1.17 to 1.50, sensitivity decreased (range: 77 to 9%) but specificity increased (range: 58 to 96%). Same-day and CMA F:P cutoffs at which a balance was reached between sensitivity and specificity ranged from 1.18 to 1.22; however, even at these values we found high rates of false positives and negatives (range: 31-39%). These results suggest that inline milk F:P data from inconsistently calibrated sensors should not be used alone to detect HYK in AMS herds.

Short communication: Effect of barn climate and management-related factors on bovine colostrum quality

Several factors have been reported to influence colostrum quality (immunoglobulin concentration). To date, knowledge of the influence of climatic factors in association with other potential influencing factors on colostrum quality is scarce. Associated influential factors are parity, body condition score, length of dry period, ration fed ante partum (AP), β-hydroxybutyrate postpartum (PP), milk yield, milk fat and protein, as well as somatic cell counts from previous and current lactation. The objective of the present study was to examine the effect of barn climate and the aforementioned factors on colostrum quality. Data were collected from 1,381 multiparous Holstein Friesian cows kept on one dairy farm over a period of one year (August 2014 to August 2015). Colostrum was harvested on farm within 1 h PP. The quantity and quality of first colostrum (estimated by Brix refractometry) were recorded for each cow. Additional data recorded were parity, body condition score at drying off, length of dry period, ration fed AP, milk yield data from previous and current lactation, milk somatic cell counts, and β-hydroxybutyrate PP. During the study period, temperature and humidity were recorded in the barn every hour, and temperature-humidity-index (THI) was calculated. Linear regression was performed with colostrum quality as the dependent variable. In the final model, colostrum quantity (L), length of dry period, parity, and climatic factors (specifically, median humidity in the 3rd week AP and hours with THI ≥72 in the last 14 and 21 d AP, respectively) were significant. Colostrum quality improved with parity and length of dry period and decreased with colostrum quantity, humidity, and hours with a THI ≥72. A classification and regression tree analysis revealed that colostrum quantity was the most important factor in this model [normalized importance (NI) 100%]. Parity (NI 42.7%), length of dry period (NI 37.1%), and climatic factors (NI 0.4 to 1.9%) followed with decreasing importance. These results indicate that the most important factors for colostrum quality (i.e., colostrum quantity and parity) may not be influenced by management. The 2 factors that can be influenced by management [i.e., length of dry period and THI (e.g., by cooling)], were quantitatively of minor importance compared with the other 2 factors. Further studies are necessary to determine whether changing these factors can improve colostrum quality significantly.

Evaluation of the Precision Xtra meter for monitoring blood β-hydroxybutyrate concentrations in late-gestation ewes

Blood samples were collected from late-gestation ewes to determine the agreement of a point-of-care (POC) Precision Xtra meter and a standard laboratory test for β-hydroxybutyrate (BHBA). Fresh whole blood samples were immediately tested with the POC instrument, and serum samples were analyzed with a standard commercial biochemical analyzer. Ewes were classified as having ketonemia if their BHBA concentrations were ≥800 µmol/L. Scatter plots, paired t-tests, Bland-Altman limits of agreement, and Gwet AC1 tests were used to compare results. The 2 tests had very good agreement. The values between instruments were not statistically different based on paired t-tests ( p = 0.312). The intercept and slope of a linear mixed model, containing the standard test results as an outcome and the POC meter results as a predictor, were 0.02 (95% CI: 0.00, 0.04) and 0.98 (95% CI: 0.96, 1.01), respectively. When the samples were classified into ketonemic classes (non-ketonemic and ketonemic) based on BHBA concentrations obtained from each test, the Gwet AC1 statistic was 0.94 (95% CI: 0.91, 0.97; p < 0.001). The ketosis classification agreed in 95% of samples. Based on the Bland-Altman plot and limits of agreement, the optimal cutoff to diagnose ketonemia with the POC meter was 1,000 µmol/L, which is 200 µmol/L higher than the laboratory BHBA medical decision limit. The Precision Xtra meter provided excellent correlation and substantial agreement with the standard laboratory technique for measuring blood BHBA in late-gestation ewes.

Evaluation of the Nova Vet Meter for sheep-side monitoring of β-hydroxybutyric acid (BHBA) and description of ewe BHBA during late gestation in three flocks from the Northeastern U.S

Prevention of metabolic diseases in small ruminants may improve production efficiency and profitability, yet ewes carrying multiples or who are in poor body condition are at increased susceptibility to develop ketosis. This study evaluated the hand-held Nova Vet Meter to accurately detect β-hydroxybutyric acid (BHBA) concentrations in ewes and determined the percentage of ewes at moderate (0.8 to 1.5 mmol/L BHBA) and greatest (≥1.6 mmol/L BHBA) risk to develop ketosis during late gestation. To validate the Nova Vet Meter, BHBA concentrations of 104 paired blood samples were measured using the Nova Vet Meter and gold-standard laboratory analysis. Receiver operating characteristics were calculated. The accuracy and sensitivity of detecting BHBA concentrations at 0.8 to 1.5 mmol/L were 94.2% and 97.3%, respectively. The accuracy and sensitivity of detecting BHBA concentrations ≥ 1.6 mmol/L were 98.0% and 50.0%, respectively. Ewe body weight (BW), body condition score (BCS), and BHBA of 117 ewes from three flocks were determined weekly during the four weeks before parturition. During the last three weeks of gestation >20% of ewes were identified with moderate risk to develop ketosis. During the last four weeks of gestation, ewes carrying triplets had reduced BCS (P = 0.0002) and increased BHBA concentrations (P < 0.0001) compared with singleton and twin pregnancies. Ewe BHBA did not correlate with lamb birth weight (R² = 0.003; P = 0.41). In conclusion, the Nova Vet Meter is suitable for sheep-side BHBA monitoring between 0.8 and 1.5 mmol/L, but further testing is necessary to evaluate BHBA readings ≥1.6 mmol/L.

Short communication: Repeatability of β-hydroxybutyrate measurements in capillary blood obtained from the external vulvar skin

The primary objective of this study was to evaluate the repeatability of measurements of β-hydroxybutyrate (BHB) concentrations in capillary blood obtained from minimal-invasive puncturing of different sites at the external vulva skin of dairy cows. A total of 240 multiparous cows sampled once within 21 d in milk were enrolled in the study. Capillary blood samples were obtained from the right and left labium of the external vulva skin and additionally from a site close to the first puncture. Samples were analyzed by using an electronic hand-held device [FreeStyle Precison Neo (FSP-Neo), Abbott GmbH & Co., Wiesbaden, Germany)]. Additionally, samples from a coccygeal vessel were analyzed as reference in a laboratory. Mean deviations (± standard deviation) between the 3 capillary sampling sites ranged from 0.01 ± 0.14 (left vs. right labium) to 0.02 ± 0.13 mmol/L (left or right labium vs. additional site). The BHB concentrations in capillary blood compared with the reference showed a mean deviation of 0.14 ± 0.18 mmol/L. The Spearman correlation coefficient between BHB concentrations in capillary blood and coccygeal blood was 85.4%. Mixed model analyses showed no significant effect of sampling site or squeezing the skin during sampling procedures on the differences toward the reference. Based on laboratory BHB concentrations of ≥1.2 and ≥1.4 mmol/L, respectively, the prevalence of hyperketonemia was 10.4 (n = 25) and 5.0% (n = 12). Thresholds to detect hyperketonemia with the FSP-Neo were optimized by receiver operating characteristic analyses. Based on a laboratory BHB concentration of ≥1.2 mmol/L thresholds were determined as 1.1 (left labium, 2nd puncture) and 1.0 mmol/L (right labium), with sensitivities between 94 and 99% and specificities between 89 and 97%. Based on a serum BHB concentration of 1.4 mmol/L, receiver operating characteristic analyses resulted in optimized cutoffs of 1.4 mmol/L for all sampling sites at the vulva, with sensitivities of 100% and specificities between 96 and 99%. In conclusion, vulvar capillary blood is suitable for accurate measuring of BHB concentrations by using the FSP-Neo. After adjusting the thresholds, the FSP-Neo provides very good test characteristics independent of the capillary sampling site or squeezing the skin and allows a practical and reliable screening tool for dairy cows.

Glucose concentration in capillary blood of dairy cows obtained by a minimally invasive lancet technique and determined with three different hand-held devices

BACKGROUND

Dairy cows have a massive demand for glucose at the onset of lactation. A poor adaption to this period leads to an excessive negative energy balance with an increased risk for ketosis and impaired animal health and production. Besides the measurement of ketones, analysing the glucose concentration in blood is reported as helpful instrument for diagnosis and differentiation of ketosis. Monitoring metabolic parameters requires multiple blood sampling. In other species, new blood sampling techniques have been introduced in which small amounts of blood are rapidly analysed using electronic hand-held devices. The objective of this study was to evaluate the suitability of capillary blood for blood glucose measurement in dairy cows using the hand-held devices FreeStyle Precision (FSP, Abbott), GlucoMen LX Plus (GLX, A. Menarini) and the WellionVet GLUCO CALEA, (WGC, MED TRUST). In total, 240 capillary blood samples were obtained from dry and fresh lactating Holstein-Friesian cows. Blood was collected from the skin of the exterior vulva by using a lancet. For method comparison, additional blood samples were taken from a coccygeal vessel and analyzed in a laboratory. Glucose concentrations measured by a standard laboratory method were defined as the criterion standard.

RESULTS

The Pearson correlation coefficients between the glucose concentrations analyzed in capillary blood with the devices and the reference were 73% for the FSP, 81% for the GLX and 41% for the WGC. Bland-Altman plots showed biases of -18.8 mg/dL for the FSP, -11.2 mg/dL for the GLX and +20.82 mg/dL for the WGC. The optimized threshold determined by a Receiver Operating Characteristics analysis to detect hyperglycemia using the FSP was 43 mg/dL with a sensitivity (Se) and specificity (Sp) of 76 and 80%. Using the GLX and WGC optimized thresholds were 49 mg/dL (Se = 92%, Sp = 85%) and 95 mg/dL (Se = 39%, Sp = 92%).

CONCLUSIONS

The results of this study demonstrate good performance characteristics for the GLX and moderate for the FSP to detect hyperglycemia in dairy cows using capillary blood. With the study settings, the WGC was not suitable for determination of glucose concentrations.

Glucose concentration in capillary blood of dairy cows obtained by a minimally invasive lancet technique and determined with three different hand-held devices

Background

Dairy cows have a massive demand for glucose at the onset of lactation. A poor adaption to this period leads to an excessive negative energy balance with an increased risk for ketosis and impaired animal health and production.

Besides the measurement of ketones, analysing the glucose concentration in blood is reported as helpful instrument for diagnosis and differentiation of ketosis. Monitoring metabolic parameters requires multiple blood sampling. In other species, new blood sampling techniques have been introduced in which small amounts of blood are rapidly analysed using electronic hand-held devices.

The objective of this study was to evaluate the suitability of capillary blood for blood glucose measurement in dairy cows using the hand-held devices FreeStyle Precision (FSP, Abbott), GlucoMen LX Plus (GLX, A. Menarini) and the WellionVet GLUCO CALEA, (WGC, MED TRUST). In total, 240 capillary blood samples were obtained from dry and fresh lactating Holstein-Friesian cows. Blood was collected from the skin of the exterior vulva by using a lancet. For method comparison, additional blood samples were taken from a coccygeal vessel and analyzed in a laboratory. Glucose concentrations measured by a standard laboratory method were defined as the criterion standard.

Results

The Pearson correlation coefficients between the glucose concentrations analyzed in capillary blood with the devices and the reference were 73 % for the FSP, 81 % for the GLX and 41 % for the WGC. Bland-Altman plots showed biases of −18.8 mg/dL for the FSP, -11.2 mg/dL for the GLX and +20.82 mg/dL for the WGC. The optimized threshold determined by a Receiver Operating Characteristics analysis to detect hyperglycemia using the FSP was 43 mg/dL with a sensitivity (Se) and specificity (Sp) of 76 and 80 %. Using the GLX and WGC optimized thresholds were 49 mg/dL (Se = 92 %, Sp = 85 %) and 95 mg/dL (Se = 39 %, Sp = 92 %).

Conclusions

The results of this study demonstrate good performance characteristics for the GLX and moderate for the FSP to detect hyperglycemia in dairy cows using capillary blood. With the study settings, the WGC was not suitable for determination of glucose concentrations.