Adipose Tissue Oxylipin Profile Changes with Subclinical Ketosis and Depot in Postpartum Dairy Cows.

Lipolysis of adipose tissue is a natural occurrence during the periparturient period in dairy cows. However, when lipolysis rates exceed the capacity of other tissues to utilize nonesterified fatty acids (NEFA), it may lead to the development of ketosis and other diseases. Additionally, polyunsaturated NEFA (PUFA) can become oxidized into oxylipins, which modulate inflammation and metabolism. The objective of this work was to identify depot-specific differences on adipose tissue oxylipin profile in dairy cows with and without subclinical ketosis and assess the effects of oxylipins on adipocyte function in vitro. Subcutaneous adipose tissue from the flank (SAT) and visceral adipose tissue from the omentum (VAT) were collected through laparotomy from multiparous dairy cows (5-14 d in milk) and grouped according to blood ß-hydroxybutyrate (BHB) into non-ketotic (NK; n = 5; BHB ≤ 0.8 mmol/L) and subclinical ketotic (SCK; n = 5; BHB 1.4 and ≤ 2.6 mmol/L). A targeted lipidome capable of detecting a 154 oxylipins was performed in paired SAT and VAT samples from all animals. Data were analyzed using the PROC GLIMMIX procedure in SAS (v9.4, SAS Institute Inc., Cary, NC, USA) for the effect of depot (SAT, VAT), ketosis status (SCK, NK), and their interaction (depot × ketosis status) on oxylipin abundance. The oxylipins thromboxane-B2 (TXB2), prostaglandin-A2 (PGA2), and 5-hydroxeicostretanoic acid (5-HETE) were selected from lipidomic data based on effects of ketosis status and depot-specificity to further investigate their effects on SAT and VAT adipocyte function. Lipidomic data revealed 50 oxylipins across both adipose tissue depots. SCK was associated with a decreased abundance of TXB2 and tended to associate with an increase in prostaglandinA2 (PGA2) and prostaglandinE1 (PGE1). Additionally, PGE1, 15-keto-prostaglandin-E2 (15-Keto-PGE2), 13,14-dihydro-15-keto-prostaglandin-E2 (13-14dh-15k-PGE2), 5-HETE, and 15-HETE were increased in SAT. While VAT had a greater abundance of 9,10-dihydroxy-12Z-octadecenoic acid (9,10-DiHOME), 12,13-dihydroxy-9Z-octadecenoic acid (12,13-DiHOME), 9-oxo-10E,12Z,15Z-octadecatrienoic acid (9-OxoOTrE) and 13S-hydroxy-9Z,11E,15Z-octadecatrienoic acid (13(s)-HOTrE). In vitro, AVG dose of 5-HETE on VAT cells tended to increase proliferation at d 7 compared with the control, HIGH dose of TXB2 tended to decrease lipid accumulation in SAT compared with control, and AVG dose of PGA2 on VAT cells tended to lower ROS compared with the control. Overall, postpartum dairy cows have depot-specific adipose tissue lipidomic profiles which are associated with changes in ketosis status.

Pre- and postpartum metabolizable protein supply: II. Effects on plasma amino acids and markers of tissue mobilization in transition Holstein dairy cows.

The influence of diet composition on the degree of adipose and lean muscle mobilization and concentrations of circulating AA has been demonstrated during the transition period. Altering the MP supply might offer a strategy to control tissue mobilization and increase circulating AA availability, but the optimum supply of MP fed pre- and postpartum remains unknown. We investigated the effect of increasing the MP supply in the prepartum, postpartum, or both diets on plasma AA concentrations and ultrasound and circulating indicators of tissue mobilization. Multiparous Holstein cows (n = 96) were assigned to 1 of 4 treatment groups at 28 d before expected calving following a randomized block design. Prepartum diets were formulated to contain either a control (C; 85 g of MP/kg DM; 1,175 g of MP/d) or high (H; 113 g of MP/kg DM; 1,603 g of MP/d) level of estimated MP. From calving to 21 DIM, fresh diets were formulated to contain either a control (C; 104 g of MP/kg DM; 2,044 g of MP/d) or high (H; 131 g of MP/kg DM; 2,685 g of MP/d) level of estimated MP. To control the potential confounding effect of Met and Lys supply, diets were formulated to supply an equal amount at 1.24 and 3.84 g/Mcal of ME in both prepartum diets and 1.15 and 3.16 g/Mcal of ME in both postpartum diets, respectively. The combination of a pre- and postpartum diet resulted in 4 treatment groups: 1) CC (n = 23), 2) CH (n = 24), 3) HC (n = 22), and 4) HH (n = 23). A common lactation diet (113 g of MP/kg DM; 2,956 g of MP/d) was fed from 22 DIM to the end of the observation period at 42 DIM. Transcutaneous ultrasonography was used to determine the longissimus dorsi muscle diameter and backfat thickness. Concentrations of plasma AA, 3-methylhistidine (3MH), and creatinine were determined on a subset of cows (n = 60) using ultra-high-performance liquid chromatography and mass spectrometry. Treatment did not affect the longissimus dorsi muscle diameter from -14 to 21 d relative to calving, but the diameter was greater in CH compared with HH at 40 DIM. Backfat thickness and the ratio of 3MH to creatinine did not differ by treatment. Concentrations of EAA were greater at -13 d relative to calving in HH compared with CC and CH and at -6 d relative to calving EAA concentrations were higher in HC compared with CC. Cows fed the H diet postpartum had elevated EAA concentrations at 6 and 20 DIM compared with cows fed the C postpartum diet but EAA concentration did not differ at 40 DIM. Total NEAA concentrations were higher in CH compared with HC and HH at -6 d relative to calving, but NEAA concentration did not differ by treatment at -13, 6, 20, or 40 d relative to calving. In conclusion, increasing the supply of MP fed prepartum, postpartum, or both had minimal effects on tissue mobilization but influenced concentrations of plasma AA.

Pre- and postpartum metabolizable protein supply: I. Effects on feed intake, lactation performance, and metabolic markers in transition dairy cows.

The objective of this study was to investigate the effect of increasing MP supply in the prepartum, postpartum, or both diets on intake, performance, and metabolic indicators. Multiparous Holstein cows (n = 96) were assigned to 1 of 4 treatment groups at 28 d before expected calving following a randomized block design. Prepartum diets were formulated to contain either a control (C; 85 g of MP/kg DM) or high (H; 113 g of MP/kg DM) level of estimated MP. From calving to 21 DIM, diets were formulated to contain either a control (C; 104 g of MP/kg DM) or high (H; 131 g of MP/kg DM) level of estimated MP. To control the potential confounding effect of Met and Lys supply, diets were formulated to supply an equal amount at 1.24 and 3.84 g/Mcal of ME in both prepartum diets and 1.15 and 3.16 g/Mcal of ME in both postpartum diets, respectively. The combination of a pre- and postpartum diet resulted in 4 treatment groups: 1) CC (n = 23), 2) CH (n = 24), 3) HC (n = 22), and 4) HH (n = 23). A common lactation diet (113 g of MP/kg DM) was fed from 22 DIM to the end of the observation period at 42 DIM. Milk yield and DMI were collected daily, and plasma metabolic indicators (BHB, fatty acids [NEFA], urea nitrogen [PUN], and glucose) were determined twice weekly from -28 to 28 d relative to calving and once weekly from 29 to 42 DIM. Samples with BHB ≥1.2 mmol/L between 3 and 10 DIM were considered hyperketonemia events. Milk composition was determined weekly. Milk yield during 1 to 21 DIM was greater in HH (44.7 ± 1.0 kg/d) compared with CC (39.2 ± 1.0 kg/d) and HC (38.0 ± 1.0 kg/d) and milk yield in CH (42.4 ± 0.9 kg/d) was greater than HC, respectively. From 22 to 42 DIM, milk yield was greater in CH (53.3 ± 1.0 kg/d) and HH (54.1 ± 1.0 kg/d) compared with CC (49.6 ± 1.0 kg/d) and HC (49.3 ± 1.0 kg/d). Dry matter intake (% of BW) and concentrations of milk protein, fat, and total solids were not affected by treatment. Prepartum concentrations of PUN were greater in H compared with C. From 1 to 21 DIM, PUN concentrations were greater in CH and HH compared with CC and HC. From 1 to 21 DIM, glucose concentrations were lower in HH compared with HC and BHB were greater in CH and HH compared with HC. Concentrations of NEFA, as well as the number of hyperketonemia events did not differ by treatment during this time. From 22 to 42 DIM, concentrations of NEFA were greater in HH compared with HC and concentrations of BHB were greater in CH and HH compared with HC. Overall, feeding CH or HH increased lactation performance without altering intake or hyperketonemia events. Results from this study support formulating a fresh diet to reduce the negative MP balance during early lactation.

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 ß-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.

Effects of postbiotic products from Saccharomyces cerevisiae fermentation on lactation performance, antioxidant capacities, and blood immunity in transition dairy cows.

This study aimed to evaluate the effects of dietary supplementation with different types of Saccharomyces cerevisiae fermentation products (SCFP) on lactational performance, metabolism, acute phase protein response, and antioxidant capacities in dairy cows from -21 to 56 d in milk (DIM). One hundred and 80 multiparous Holstein dairy cows were blocked by parity, expected calving date, pre-trial body condition score, and previous 305-d ME yield, and then randomly assigned to 1 of 3 dietary treatments: basal diet (CON; n = 60), basal diet supplemented with 40 g/d of SCFP1 (XPC; n = 60; XPC, Diamond V, Cedar Rapids, IA), and basal diet supplemented with 19 g/d of SCFP2 (NTK; n = 60, NutriTek®, Diamond V, Cedar Rapids, IA). Blood (n = 15, 13 and 12 in the CON, XPC and NTK groups, respectively) was sampled at -7 ± 3, + 3, + 7, + 21, and + 28 d, and milk samples (n = 19, 18 and 15 in the CON, XPC and NTK groups, respectively) was sampled during 1-8 wk from a subset of cows from -21 to 56 d relative to calving. Data were analyzed using the MIXED procedure in SAS (SAS Institute Inc.). All data were subjected to repeated measures ANOVA. Dietary treatment (TRT), time, and their interaction (TRT × time) were considered as fixed effects and cow as the random effect. Cows fed XPC and NTK had greater energy-corrected milk (ECM). Supplementing NTK increased milk fat content and yield, and 3.5% fat-corrected milk (FCM) yield compared with CON. Milk urea nitrogen (MUN) was lower in XPC cows than CON. SCFP supplementation decreased plasma ß-hydroxybutyrate (BHB), ceruloplasmin (CER), haptoglobin (HPT), and interleukin-1ß (IL-1ß) concentrations, whereas increased plasma phosphorus (P) concentrations. In addition, cows fed NTK showed lower creatinine (CR) and cortisol (COR) concentrations but increased plasma calcium (Ca) and myeloperoxidase (MPO) concentrations than those in the CON cows. In addition, cows fed NTK and XPC both had reduced plasma concentrations of serum amyloid-A (SAA) at 3 DIM of lactation compared with CON fed cows. Furthermore, SCFP cows had greater concentrations of plasma glucose (GLU) and calcium (Ca) than CON cows at 7 DIM, and greater concentrations of plasma phosphorus (P) at 21 DIM. Between different SCFP type fed groups, plasma concentrations of nonesterified fatty acids (NEFA), MDA, creatinine (CR), SAA, and HPT were lower in cows fed NTK compared with cows fed XPC at 7 DIM. Overall, our results indicate the potential benefits of supplementing SCFP in transition dairy cows by modulating immunity, liver metabolic function and supporting ECM yield. The results also suggest that NutriTek at 19 g/d appears to support the performance and health of dairy cows better compared with XPC at 40 g/d, based on improved metabolic and inflammatory status during the transition period.

Effect of F-isoprostane class on cow peripheral blood neutrophil microbicidal function in vitro.

Isoprostanes (isoP) are formed during conditions of oxidative stress (OS) through the oxidation of cell membrane fatty acids. Different classes of isoP are formed depending on the fatty acid being oxidized but the biological activity of these molecules in innate immune cells is poorly understood. Thus, the objective of this study was to compare in vitro the effects of F2- and F3-isoP on neutrophil microbicidal functions. We isolated neutrophils from 6 dairy cows and incubated them for 8 h at various concentrations of F2- and F3-isoP. Then, microbicidal function was assessed in terms of phagocytosis, respiratory burst, myeloperoxidase activity, and extracellular trap formation. In vitro supplementation with F3-isoP enhanced microbicidal capabilities whereas supplementation with F2-isoP decreased or did not impact these microbe killing functions. Hence, favoring the production of F3- over F2-isoprostanes may be a strategy to augment neutrophils' functional capacity during OS conditions. This should be tested in vivo.

Graduate Student Literature Review: Exploring choline's important roles as a nutrient for transition dairy cows.

In late gestation and in the first weeks postpartum, lipid droplets accumulate in the hepatic tissue resulting in approximately 40% to 50% of the dairy cows developing hepatic lipidosis in the first weeks of lactation. Elevated concentrations of triacylglycerol in the hepatic tissue are associated with increased risk of peripartum diseases and impaired productive performance. Cows with hepatic lipidosis need to dispose the excess of hepatic triacylglycerol, but this is a slow process in the bovine liver and relies on primary mechanisms such as complete oxidation and ketogenesis because of the limited export of triacylglycerols as lipoproteins. Choline is a lipotropic compound because, among other functions, it facilitates the export of lipids from the liver. Supplementing choline as rumen-protected choline (RPC) to diets of feed-restricted dairy cows reduces the degree of triacylglycerol infiltration into the hepatic parenchyma in part by enhancing export of triacylglycerol as nascent lipoprotein. The reduced accumulation of triacylglycerol in hepatic tissue in feed-restricted cows fed RPC might affect secondary pathways involved in hepatic disposal of fatty acids such as increased cellular autophagy and lipophagy and minimize endoplasmic reticulum stress response and hepatocyte inflammation. Collectively, these effects on secondary pathways might further reduce the severity of hepatic lipidosis in cows. One of the benefits of supplementing RPC is improved fat digestibility, perhaps because choline, through phosphatidylcholines, facilitates lipid transport within the enterocyte by increasing the synthesis of chylomicrons. Finally, when supplemented during the transition period, RPC improves productive performance of cows, irrespective of their body condition, that extends well beyond the period of supplementation. This review summarizes the current understanding of hepatic lipidosis in early lactation, recapitulates the absorption, transport and metabolism of choline, and discusses its role on hepatic metabolism and gastrointestinal functions, which collectively results in improved performance in dairy cows.

Prepartum behaviors as early indicators for postpartum energy associated biomarkers status in Holstein dairy cows.

Our main aim was to investigate the predictive value of prepartum behaviors such as total daily rumination (TDR), total daily activity (TDA) and dry matter intake (DMI) as early indicators to detect cows at risk for hyperketonemia (HYK), hypoglycemia (HYG) or high non-esterified fatty acid (NEFA) status in the first (wk1) and second week (wk2) postpartum. In a case control study, 64 Holstein cows were enrolled 3 weeks before the expected time of calving and monitored until 15 days in milk (DIM). Postpartum blood samples were taken at D3 and D6 for wk1 and at D12 and D15 for wk2 to measure beta-hydroxybutyrate, NEFA and glucose concentration. Ear-mounted accelerometers were used to measure TDR and TDA. DMI and milk yield were obtained from farm records. Relationships between the average daily rate of change in prepartum TDR (ΔTDR), TDA (ΔTDA), and DMI (ΔDMI) with postpartum HYK, HYG and NEFA status in wk1 and wk2 post-partum were evaluated using linear regression models. Models were adjusted for potential confounding variables, and covariates retained in the final models were determined by backward selection. No evidence was found to support the premise that prepartum ΔTDR, ΔTDA or ΔDMI predicted postpartum HYK, HYG or NEFA status in wk1 or in wk2. Overall, prepartum ΔTDR, ΔTDA and ΔDMI were not effective predictors of HYK, HYG or NEFA status in the first 2 weeks postpartum.

Predictive modelling of deviation from expected milk yield in transition cows on automatic milking systems.

The transition period is a pivotal time in the production cycle of the dairy cow. It is estimated that between 30% and 50% of all cows experience metabolic or infectious disease during this time. One of the most common and economically consequential effects of disease during the transition period is a reduction in early lactation milk production. This has led to the utilisation of deviation from expected milk yield in early lactation as a proxy measure for transition health. However, to date, this analysis has been used exclusively for the retrospective assessment of transition cow health. Statistical models capable of predicting deviations from expected milk yield may allow producers to proactively manage animals predicted to suffer negative deviations in early lactation milk production. The objective of this retrospective cohort study was first, to explore the accuracy with which cow-level production and behaviour data collected on automatic milking systems (AMS) from 1-3 days in milk (DIM) can predict deviation from expected 30-day cumulative milk yield in multiparous cows. And second, to assess the accuracy with which predicted yield deviations can classify cows into groups which may facilitate improved transition management. Production, rumination, and physical activity data from 31 commercial AMS were accessed. A 3-step analytical procedure was then conducted. In Step 1, expected cumulative yield for 1-30 DIM for each individual cow-lactation was calculated using a mixed effect linear model. In Step 2, 30-Day Yield Deviation (YD) was calculated as the difference between observed and expected cumulative yield. Lactations were then assigned to one of three groups based on their YD, RED Group (0% YD). In Step 3, yield, rumination, and physical activity data from days 1-3 in lactation were used to predict YD using machine learning models. Following external validation, YD was predicted across the test data set with a mean absolute error of 9%. Categorisation of animals suffering large negative deviations (RED group) was achieved with a specificity of 99%, sensitivity of 35%, and balanced accuracy of 67%. Our results suggest that milk yield, rumination and physical activity patterns expressed by dairy cows from 1-3 DIM have utility in the prediction of deviation from expected 30-day cumulative yield. However, these predictions currently lack the sensitivity required to classify cows reliably and completely into groups which may facilitate improved transition cow management.

Validation of an on-farm portable blood analyzer for quantifying blood analytes in dairy cows.

The periparturient period for dairy cows is a metabolically dynamic time period where the cow is adjusting from gestation to the onset of lactation. Metabolic disorders such as ketosis, hypocalcemia, and fatty liver occur during this time; however, tools to diagnose these diseases on-farm is limited. The need for compact metabolite quantification devices that can quantify metabolites on farm from whole blood samples is warranted. The purpose of this study was to validate a portable blood analyzer (PBA) by analyzing metabolites on privately owned dairy farms in southcentral Wisconsin. Additional tests were completed to determine if plasma metabolite quantification was similar to whole-blood quantification. Two phases were conducted on two separate farms to complete these analyses and data were analyzed by Bland-Altman plot and correlations. Metabolites quantified from whole blood samples included albumin, alanine and aspartate aminotransferases, ß-hydroxybutyrate, blood urea nitrogen, total calcium, cholesterol, creatinine kinase, γ-glutamyl transferase, glucose, magnesium, nonesterified fatty acids, phosphorous, and total protein and were analyzed in the lab after plasma separation to determine gold-standard laboratory concentrations. Across Phase 1 and 2, whole-blood PBA metabolite concentrations resulted in similar results compared to the laboratory assays. For plasma analyzed on the PBA, overall results were positively correlated, but robustness was dependent upon initial validation results indicating some metabolites are suitable for plasma quantification on the device. These results indicate that the PBA is a viable on-farm metabolite quantification tool that will be valuable for on-farm diagnosis of metabolic stress and dysfunction in transition dairy cows.

Effect of dietary phosphorus deprivation during the dry period on the liver transcriptome of high-yielding periparturient dairy cows.

Although dietary phosphorus (P) deprivation extending from the dry period into early lactation impairs health and productivity of cows, restricting dietary P supply during the dry period not only appears to be innocuous but rather effectively mitigates hypocalcemia during the first wk of lactation. To investigate possible negative metabolic effects of P deprivation during the dry period, the present study tested the hypothesis that restricted dietary P supply during the dry period alters the liver transcriptome of dairy cows during the periparturient period. Thirty late-pregnant multiparous Holstein-Friesian dairy cows entering their second, third, or fourth lactation were assigned to either a dry cow ration with low (LP, 0.16% P in DM) or adequate P content (AP, 0.35% in DM) during the last 4 wk of the dry period (n = 15/group). Liver transcriptomics, which was carried out in a subset of 5 second-parity cows of each group (n = 5), and determination of selected hormones and metabolites in blood of all cows, was performed ∼1 wk before calving and on d 3 postpartum. Liver tissue specimens and blood samples were obtained by a micro-invasive biopsy technique from the right tenth intercostal space and puncture of a jugular vein, respectively. One hundred seventy-five hepatic transcripts were expressed differentially between LP versus AP cows in late pregnancy, and 165 transcripts differed between LP versus AP cows in early lactation (fold change >1.3 and <-1.3, P < 0.05). In late pregnancy, the enriched biological processes of the upregulated and the downregulated transcripts were mainly related to immune processes and signal transduction (P < 0.05), respectively. In early lactation, the enriched biological processes of the upregulated and the downregulated transcripts were involved in mineral transport and biotransformation (P < 0.05), respectively. The plasma concentrations of the hormones and acute-phase proteins (progesterone, insulin-like growth factor 1, serum amyloid α, haptoglobin, and 17ß-estradiol) determined were not affected by P supply. These results suggest that P deprivation during the dry period moderately affects the liver transcriptome of cows in late pregnancy and early lactation, and causes no effects on important plasma hormones and acute-phase proteins indicating no obvious impairment of health or metabolism of the cows.

Influence of prepartum dietary cation-anion difference and the magnitude of calcium decline at the onset of lactation on mineral metabolism and physiological responses.

The onset of lactation is characterized by substantially altered calcium (Ca) metabolism; recently, emphasis has been placed on understanding the dynamics of blood Ca in the peripartal cow in response to this change. Thus, the aim of our study was to delineate how prepartum dietary cation-anion difference (DCAD) diets and the magnitude of Ca decline at the onset of lactation altered blood Ca dynamics in the periparturient cow. Thirty-two multiparous Holstein cows were blocked by parity, previous 305-d milk yield and expected parturition date, and randomly allocated to either a positive (+120 mEq/kg) or negative (-120 mEq/kg) DCAD diet from 251 d of gestation until parturition (n = 16/diet). Immediately after parturition cows were continuously infused for 24 h with (1) an intravenous solution of 10% dextrose or (2) Ca gluconate (CaGlc) to maintain blood ionized (iCa) concentrations at ∼1.2 mM (normocalcemia) to form 4 treatment groups (n = 8/treatment). Blood was sampled every 6 h from 102 h before parturition until 96 h after parturition and every 30 min during 24 h continuous infusion. Cows fed a negative DCAD diet prepartum exhibited a less pronounced decline in blood iCa approaching parturition with lesser magnitude of decline relative to positive DCAD-fed cows. Cows fed a negative DCAD diet prepartum required lower rates of CaGlc infusion to maintain normocalcemia in the 24 h postpartum relative to positive DCAD-fed cows. Infusion of CaGlc disrupted blood Ca and P dynamics in the immediate 24 h after parturition and in the days following infusion. Collectively, these data demonstrate that prepartum negative DCAD diets facilitate a more transient hypocalcemia and improve blood Ca profiles at the onset of lactation whereas CaGlc infusion disrupts mineral metabolism.

Effect of pre- and postpartum supplementation of a pure glycerol product to dairy cows on feeding behavior, lying behavior, and reticulorumen pH.

The objective of this study was to quantify the effects of supplementing a low level of dry glycerol product pre- and postpartum on the feeding behavior, lying behavior, and reticulorumen pH of dairy cows. Multiparous Holstein dairy cows (n = 60) were enrolled in a 2 × 2 factorial design study. Twenty-one days before expected parturition, cows individually received a dry cow diet with (1) 250 g/d glycerol supplementation (GLY; 66% pure glycerol, United States Pharmacopeia grade), or (2) no supplementation (CON). Following parturition, cows were individually assigned to either (1) 250 g/d glycerol product (GLY; 66% pure glycerol), or (2) no supplementation (CON) to their partial mixed ration (PMR) for the first 21 d in milk (DIM). All cows were milked by an automated milking system and offered a target of 5.4 kg/d pellet (23% of target total dry matter intake [DMI]). For both treatment periods, cows were individually assigned to automated feed bins to measure PMR feeding behavior. Rumination time and lying behavior were monitored with electronic sensors for the whole study (-21 to 21 DIM). Reticulorumen pH boluses were administered to a subset of cows (n = 40) where pH was recorded every 10 min from 21 d prepartum to 21 d postpartum. Prepartum, cows fed GLY had fewer, larger meals and spent 20.2% more time feeding than CON while consuming feed at a similar rate. Cows on the CON diet prepartum spent more time lying down in more frequent bouts in the 21 d before calving. Following parturition, cows that received GLY prepartum continued to devote more time to eating, while tending to spend less time ruminating per kilogram of DMI. Cows receiving CON postpartum had larger meals with longer intervals between meals. In the first 21 DIM, cows receiving CON prepartum tended to have shorter, but significantly more frequent, lying bouts than cows fed GLY prepartum. Glycerol supplementation pre- and postpartum resulted in less time spent lying down following parturition. Minimal differences between treatments were observed for pre- and postpartum sorting behavior or reticulorumen pH. Overall, supplementation of glycerol pre- and postpartum altered cow time budgets, with cows spending more time eating pre- and postpartum, less time lying pre- and postpartum, and having fewer, larger meals prepartum when receiving glycerol prepartum, and with cows having slower feeding rates and smaller meals following parturition with postpartum glycerol supplementation.

Effects of dietary chromium supplementation on blood biochemical parameters in dairy cows: A multilevel meta-analytical approach.

Chromium (Cr) has been reported to modulate blood biochemistry in dairy cows. However, there is a discrepancy in the literature regarding the effects of dietary Cr supplementation on various blood parameters. This meta-analysis aimed to evaluate the effects of Cr supplementation in dairy cows on blood glucose, insulin, glucagon, nonesterified fatty acid (NEFA), cortisol, and serum total protein (STP) concentrations. Following relevant literature data extraction, a 3-level meta-analytical random effect model was fitted to the data expressed as standardized mean difference (SMD) of outcome measures of control versus Cr-supplemented cows (i.e., difference in mean between control and treatment group or pooled standard deviation). The SMD can be categorized as having a small effect (0.20), a moderate effect (0.50), and a large effect (0.80). The meta-regression identified the potential sources of heterogeneity, including the body weight of cows, experimental duration/duration of Cr supplementation, blood sampling time (3 wk before parturition until 4 wk after parturition categorized as the transition period, else as the nontransition period), and form of Cr complexes. Blood glucose did not differ significantly between control and Cr-supplemented cows with an estimated SMD of µ = 0.0071 (95% confidence interval [CI]: -0.212 to 0.226). The effect of Cr supplementation on blood insulin was also nonsignificant with an SMD of µ = 0.0007 (95% CI: -0.191 to 0.193). Cows receiving Cr supplements had significantly higher levels of glucagon than controls (95% CI: 0.116 to 0.489), with an estimated SMD = 0.303. Combined transition and nontransition data suggest Cr supplementation did not affect the concentration of NEFA. However, in transition cows, Cr supplementation significantly decreased blood NEFA levels as compared with controls (95% CI: -0.522 to -0.0039), with estimated SMD = -0.263. The estimated SMD was µ = -0.1983 (95% CI: -0.734 to 0.337) for cortisol and -0.0923 (95% CI: -0.316 to 0.131) for total protein. In summary, Cr supplementation in the transition cows decreased NEFA concentration. Blood glucose, insulin, cortisol, and STP concentrations were unaffected. However, Cr supplementation increased glucagon concentration.

Evaluation of the relationship between ionized and total calcium concentrations in blood during the first week of lactation in dairy cows.

BACKGROUND: Diagnosis of subclinical hypocalcemia in cattle is based on concentration of total Ca ([TCa]) in serum or plasma below the reference range, with [TCa] serving as proxy for the concentration of ionized Ca ([iCa]). HYPOTHESIS/OBJECTIVES: To investigate the relation between [iCa] and [TCa] in periparturient cows over time, and its association with various metabolites. ANIMALS: Thirty periparturient dairy cows. METHODS: Prospective observational study. Blood from periparturient cows was obtained between 4 days before and 7 days after calving. Samples underwent blood gas analysis and blood biochemical analysis. The ratio of [iCa] : [TCa] was computed. Repeated measures linear regression analyses, spearman correlation-, Deming regression- and receiver operating characteristic (ROC) analyses were conducted. RESULTS: Correlations between [iCa] and [TCa] ranged from r = 0.55 to r = 0.84. The diagnostic value of [TCa] to identify cows with [iCa] below the arbitrary cut-off of 1.1 mmol/L was weak in particular during the first 24 hours of lactation, but continuously improved toward the end of the study with areas under the ROC curve increasing from 0.64 at d 0 to 0.93 at d +4 after calving. Strongest association with [iCa] : [TCa] were found for albumin (r2 = 0.58, P < .0001), pCO2 (r2 = 0.45, P = .0003), the standard [HCO3 ] (r2 = 0.22, P = .01), lactate (r2 = 0.16, P = .04) and [NEFA] (r2 = 0.15, P = .05). CONCLUSION AND CLINICAL IMPORTANCE: The [TCa] is of limited value to identify cows with subnormal [iCa] in the first hours and days of lactation, a finding apparently attributable to the increased variation of a number of metabolic variables that affect the ratio of [iCa] : [TCa].

Transition Cow Nutrition and Management Strategies of Dairy Herds in the Northeastern United States: Associations of Nutritional Strategies with Analytes, Health, Milk Yield, and Reproduction.

The objective was to identify relationships between transition cow nutritional strategies and the prevalence of elevated analytes (nonesterified fatty acids (NEFA), ß-hydroxybutyrate (BHB), and haptoglobin (Hp)), disorder incidence (DI), milk yield, and reproductive performance. Multiparous and primiparous cows from 72 farms in the northeastern US were enrolled in a herd-level cohort study. Farms were dichotomized within parity into a nutritional strategy within each period; far-off: controlled energy (CE; <16.5% starch and ≥40% forage neutral detergent fiber (FNDF)) or not CE (NCE; ≥16.5% starch or <40% FNDF or both), close-up: high FNDF (HF; ≥40% FNDF) or low FNDF (LF; <40% FNDF), and fresh: low starch (LS; <25.5% starch) or high starch (HS; ≥25.5% starch). No evidence existed that transition cow nutritional strategies were associated with milk yield outcomes (p ≥ 0.20). In general, our results support feeding multiparous cows HF close-up and HS fresh to minimize excessive BHB and DI; however, multiparous cows fed LF close-up had a higher pregnancy rate, and lower prepartum NEFA and Hp. Similarly, our results support feeding primiparous cows CE far-off, HF close-up, and HS fresh to maximize reproductive performance, and minimize BHB and DI; however, herds fed HF close-up or HS fresh had higher Hp.

Comparison of two different anionic supplements and a low calcium diet fed to transition cows prepartum on DM intake, mineral homoeostasis and performance.

This study evaluates the effects of two rations with a positive dietary cation-anion difference (DCAD) and varying Ca content and two anionic diets on mineral homoeostasis and performance in early lactation cows. For this purpose, 48 pregnant dairy cows stratified for mature equivalent milk production, parity, body condition score (BCS), and BW were randomly assigned to four treatment groups and fed the following rations during the last 3 weeks of gestation: LC: low Ca (0.24% Ca, 1.14% K, DCAD: +86 mEq/kg DM), HC: high Ca (1.23% Ca, 1.17% K, DCAD: +95 mEq/kg DM), AS: Anionic salt (1.21% Ca, 1.21% K, DCAD: -112 mEq/kg DM, and SC: SoyChlor (1.28% Ca, 1.16% K, DCAD: -115 mEq/kg DM). After parturition, all animals were fed a common postpartum diet. Data were collected until 21 days in milk. Urinary pH was significantly decreased with the AS and SC treatment in comparison to the LC and HC groups. The highest prepartum DM intake (DMI) was found in the LC group, while DMI in AS cows was lowest. Postpartum, DMI was significantly greater in LC and SC cows than in animals fed the HC and AS rations. Prepartum serum concentrations of Ca, P, and Mg as well as postpartum serum concentrations of P and Mg did not differ, while postpartum Ca was lower in the HC group, especially 24 and 48 h after parturition. The greatest energy-corrected milk (ECM) yield was observed in cows fed the LC ration prepartum. Interestingly, milk protein production was lower in SC cows compared to LC, HC and AS. This study indicates that a ration containing a restricted Ca content fed prepartum is as suitable as a low DCAD diet to improve Ca balance without compromising DMI and performance.

Pre-calving energy density and rumen protected lysine impacted blood metabolites and biomarkers of liver functions in dairy cows during the transition period.

Dairy cows usually face negative energy balance and disorders of normal organ function due to a mismatch between energy intake and energy demand. Negative energy balance directly affects liver function and blood metabolites because the liver is used as source of energy supply and a center of metabolic activity. This study was aimed to determine the effect of pre-calving energy density and rumen-protected lysine on blood metabolites and biomarkers of liver functions in the dairy cows during the transition period. Forty 3rd lactation Holstein cows going to enter their 4th lactation were randomly allocated to one of the four dietary treatments (high energy with rumen-protected lysine (HERPL) = 1.53NEL plus 40 g Lys, high energy without lysine (HECK) = 1.53NEL, low energy with rumen-protected lysine (LERPL) = 1.37NEL plus 40 g Lys, and low energy without lysine (LECK) = 1.37NEL arranged in a 2 × 2 factorial design. Blood samples were collected during the transition period, and concentrations of blood metabolites and biomarkers of liver function were measured. Interaction between pre-calving high-energy diet and rumen-protected lysine tended to increase plasma albumin, numerically increased glucose, decreased triglyceride, total bilirubin, and aspartate aminotransferase concentrations. The result revealed that pre-calving high-energy density increased insulin, albumin and decreased blood urea nitrogen and total bilirubin concentrations and substantial favor liver functions during the transition period.

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 ß-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 ß-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.

Effect of replacing a portion of inorganic chloride trace minerals with trace mineral amino acid complexes.

The objective was to determine whether replacing a portion of inorganic chloride trace minerals and cobalt carbonate in the diet with AA complexes of trace minerals and cobalt glucoheptonate will improve lactating cow performance, feed efficiency, and calf performance. In a clinical trial, 69 Holstein cows entering second lactation and greater were randomly assigned to 1 of 2 treatments, with the total dietary trace mineral concentration the same between treatments, starting 1 wk after dry off (50 to 57 d before expected parturition) until 154 d in milk (DIM): (1) an inorganic chloride trace mineral (ITM) blend consisting of Zn (75 mg/kg), Mn (65 mg/kg), and Cu (10 mg/kg) as hydroxychlorides and Co (1 mg/kg) as carbonate (n = 37) or (2) partial replacement of ITM with AA complexes of Zn (40 mg/kg), Mn (20 mg/kg), and Cu (3.5 mg/kg) and Co glucoheptonate (1 mg/kg; AATM; Availa-Dairy, Zinpro Corp.; n = 32). Dry matter intake (DMI) was recorded daily from enrollment through wk 8, and milk yields were recorded daily from calving through wk 22. Milk composition and body weights (BW) were collected weekly. Serum samples were analyzed for albumin (Alb), cholesterol (Chol), total bilirubin (Bili), aspartate aminotransferase (AST), haptoglobin, ß-hydroxybutyrate (BHB), and Ca. A liver health index (LHI) was calculated based on Bili, Chol, and Alb concentrations. A liver functionality index (LFI) was calculated to standardize changes in Alb, Chol, and Bili from 4 to 29 DIM. Greater LHI and LFI indicate better health status. Colostrum was analyzed for IgG and Brix, and calf serum was analyzed for IgG. Calf growth was monitored through 9 wk of age (AATM: n = 12, ITM: n = 10). Data were analyzed using SAS software with mixed effects models and repeated-measures analysis, when applicable. Survival analysis for pregnancy by 154 DIM was analyzed by Cox proportional and Kaplan-Meier hazards models. Disorder incidence was tested with Fisher's exact test. Prepartum DMI as a percent of BW was lower in cows fed AATM and not significant postpartum. Cows fed AATM produced more milk from wk 1 to 8 and from wk 1 to 22. Energy-corrected milk yield and colostrum measures did not significantly differ between treatments. A treatment by time interaction was seen for AST and BHB; cows fed AATM tended to have lower AST concentrations at 28 DIM and lower concentrations in BHB through 29 DIM, though not statistically significant. Cows fed AATM had greater LHI at 4 DIM. Haptoglobin, Ca, LFI, hazard of pregnancy, risk to first service, survival curves, or services per pregnancy did not significantly differ. Calf serum IgG and birth weight did not significantly differ between treatments. Calves from dams fed AATM had greater average daily gain than calves from dams fed ITM. Overall, cows fed AATM during the dry period and early lactation had improved postpartum performance and potential health improvements.