Periparturient Mineral Metabolism: Implications to Health and Productivity

Mineral metabolism, in particular Ca, and to a lesser extent phosphorus (P) and magnesium (Mg), is altered with the onset of lactation because of extensive irreversible loss to synthesize colostrum and milk. The transient reduction in the concentration of Ca in blood, particularly when it lasts days, increases the risk of mineral-related disorders such as hypocalcemia and, to a lesser extent, hypophosphatemia. Although the incidence of clinical hypocalcemia can be reduced by prepartum dietary interventions, subclinical hypocalcemia remains prevalent, affecting up to 60% of the dairy cows in the first 3 d postpartum. More importantly, strong associations exist between hypocalcemia and increased susceptibility to other peripartum diseases and impaired reproductive performance. Mechanistic experiments have demonstrated the role of Ca on innate immune response in dairy cows, which presumably predisposes them to other diseases. Hypocalcemia is not related to inadequate Ca intake as prepartum diets marginal to deficient in Ca reduce the risk of the disease. Therefore, the understanding of how Ca homeostasis is regulated, in particular how calciotropic hormones such as parathyroid hormone and 1,25-dihydroxyvitamin D3, affect blood Ca concentrations, gastrointestinal Ca absorption, bone remodeling, and renal excretion of Ca become critical to develop novel strategies to prevent mineral imbalances either by nutritional or pharmacological interventions. A common method to reduce the risk of hypocalcemia is the manipulation of the prepartum dietary cation-anion difference. Feeding acidogenic diets not only improves Ca homeostasis and reduces hypocalcemia, but also reduces the risk of uterine diseases and improves productive performance. Feeding diets that induce a negative Ca balance in the last weeks of gestation also reduce the risk of clinical hypocalcemia, and recent work shows that the incorporation of mineral sequestering agents, presumably by reducing the absorption of P and Ca prepartum, increases blood Ca at calving, although benefits to production and health remain to be shown. Alternative strategies to minimize subclinical hypocalcemia with the use of vitamin D metabolites either fed prepartum or as a pharmacological agent administered immediately after calving have shown promising results in reducing hypocalcemia and altering immune cell function, which might prove efficacious to prevent diseases in early lactation. This review summarizes the current understanding of Ca homeostasis around parturition, the limited knowledge of the exact mechanisms for gastrointestinal Ca absorption in bovine, the implications of hypocalcemia on the health of dairy cows, and discusses the methods to minimize the risk of hypocalcemia and their impacts on productive performance and health in dairy cows.

Safety and efficacy of a feed additive consisting of 25-hydroxycholecalciferol monohydrate produced with Saccharomyces cerevisiaeCBS 146008 for all ruminants (DSM Nutritional Products Sp. z.o.o.)

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of 25-hydroxycholecalciferol monohydrate produced with Saccharomyces cerevisiae CBS 146008 as a nutritional feed additive for all ruminants. The additive is already authorised for use with chickens for fattening, turkeys for fattening, other poultry and pigs. The Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) concluded that the additive does not give raise to any safety concern regarding the production strain. The additive is safe for cattle for fattening and dairy cows at the maximum recommended use level of 0.1 mg 25-OH-D3/kg complete feed. This conclusion can be extended to other cattle categories and extrapolated to all ruminant species. The use of 25-OH-D3 in all ruminants under the proposed conditions of use is considered safe for the consumer. The additive is not irritant to the skin or eyes. No conclusion on its potential to be a skin sensitiser or on its effects on the respiratory system can be reached due to absence of data. The use of the additive under assessment at the recommended conditions of use is considered safe for the environment. 25-OH-D3 is an efficient source of vitamin D3 for all ruminants when used according to the proposed conditions of use.

Effect of source and amount of vitamin D on serum concentrations and retention of calcium, magnesium, and phosphorus in dairy cows

The objectives of the experiment were to determine the effects of supplementing 2 amounts of 25-hydroxyvitamin D₃ (calcidiol; CAL) compared with equal amounts of vitamin D₃ (cholecalciferol; CHOL) on serum concentrations, absorptions, and retentions of Ca, Mg, and P in periparturient dairy cows. One hundred seventy-seven (133 parous and 44 nulliparous) pregnant Holstein cows were enrolled in the experiment. Cows were blocked by parity and previous lactation milk yield (parous) or genetic merit for energy-corrected milk yield (nulliparous) and assigned randomly to receive 1 or 3 mg/d of CAL or CHOL in a 2 × 2 factorial arrangement of treatments. Treatments were provided to individual cows as a top-dress to the prepartum diet from 250 d gestation until parturition. The prepartum diet had a dietary cation-anion difference of -128 mEq/kg of dry matter. All cows were fed a common postpartum diet containing 46 μg of vitamin D₃/kg of dry matter without further supplementation of treatments. Concentrations of vitamin D metabolites, Ca, Mg, and P in serum were measured pre- and postpartum, in addition to total-tract digestibility and urinary excretion of Ca, Mg, and P in the prepartum period. Feeding 3 mg compared with 1 mg of CAL increased serum 25-hydroxyvitamin D₃ (CAL1 = 94 vs. CAL3 = 173 ± 3 ng/mL). In comparison, the increment in serum 25-hydroxyvitamin D₃ from feeding 3 mg compared with 1 mg of CHOL was small (CHOL1 = 58 vs. CHOL3 = 64 ± 3 ng/mL). Feeding CAL increased prepartum concentration of P in serum compared with CHOL (CHOL = 1.87 vs. CAL = 2.01 ± 0.02 mM), regardless of the amount fed, but neither source nor amount affected prepartum Ca or Mg in serum. Feeding CAL increased serum Ca and P for the first 11 d postpartum compared with CHOL (CHOL = 2.12 vs. CAL = 2.16 ± 0.01 mM serum Ca; CHOL = 1.70 vs. CAL = 1.78 ± 0.02 mM serum P) but the amount of vitamin D did not affect postpartum concentrations of Ca, Mg, and P in serum. Feeding CAL increased prepartum apparent digestibility of Ca compared with CHOL (CHOL = 26.6 vs. CAL = 33.5 ± 2.8%) but treatments did not affect Ca retention prepartum. Neither source nor amount of vitamin D affected Mg and P apparent digestibility, but CAL decreased the concentration of P excreted in urine during the prepartum period (CHOL = 1.8 vs. CAL = 0.8 ± 0.3 g/d). Calcidiol tended to increase the amount of Ca secreted in colostrum (CHOL = 9.1 vs. CAL = 11.2 ± 0.9 g/d) and Ca excreted in urine postpartum (CHOL = 0.4 vs. CAL = 0.6 ± 0.1 g/d) compared with CHOL. Collectively, feeding CAL at 1 or 3 mg/d compared with CHOL in the last 24 d of gestation is an effective way to increase periparturient serum P concentration and postpartum serum Ca of dairy cows fed a prepartum diet with negative DCAD.

Does bone mobilization interfere with energy metabolism in transition cows?

The onset of lactation represents a challenge for both mineral homeostasis and energy metabolism in high-performing dairy cows. It has been shown that subclinical and clinical hypocalcemia increases the risk of ketosis and recent studies suggest that bone-derived endocrine factors could play a role in intermediary metabolism. Therefore, we analyzed serum samples from calculated d -7, calculated d -3, d +1, d +3, and d +7 relative to calving from 15 multiparous cows for total Ca, the bone resorption marker CrossLaps, the bone formation marker intact osteocalcin, undercarboxylated osteocalcin (ucOC), insulin, glucose, nonesterified fatty acids, β-hydroxybutyrate, and insulin-like growth factor 1. Serum concentrations of Ca on d -3 and d +1 were associated with parameters of energy metabolism on d +3 and d +7. As we found large variations for serum concentrations of ucOC already on d -7, we allocated the cows retrospectively to 3 groups: low ucOC, medium ucOC, and high ucOC. These groups differed not only in their ucOC dynamics, but also in insulin sensitivity estimated using the revised quantitative insulin sensitivity index (RQUICKI). High ucOC cows presented with the highest RQUICKI throughout the entire observation period. Our data further support the hypothesis that low serum Ca precedes disturbances of energy metabolism. Furthermore, from our preliminary results it can be assumed that the potential link between mineral homeostasis, bone turnover, and intermediary metabolism should be further investigated.

Acidified diet is not effective in preventing hypocalcemia in dairy cows on French commercial farms

The objective of this study was to assess, in the context of typical dairy farms in western France, the preventive effects of prepartum diet acidification (AcD) and mineral intake during late gestation on the incidence of subclinical hypocalcemia (SHC) and subclinical hypophosphatemia (SHP) after calving. We conducted a longitudinal study that followed a cohort of 371 Holstein cows from 26 French dairy farms; of these, 235 cows (15 farms) were supplied with anionic salts during late gestation, and 136 cows (11 farms) were not. Blood samples were collected from 1 to 22 cows per farm (average of 14.3 cows per farm) between 24 and 48 h after calving. Total calcium and inorganic phosphorus concentrations in plasma were then quantified by inductively coupled plasma - optical emission spectrometry. The effects of AcD on the incidence of SHC and SHP were assessed using mixed linear models that evaluated the cow-level factors parity, milk yield index, and individual health events/treatments, and the farm-level factors diet calcium and magnesium content, dietary phosphorus intake, vitamin D supply, diet crude protein content, and duration of AcD, with farm as a random effect. Approximately 55% of cows were diagnosed with SHC (calcium < 2.0 mmol/l, n = 203) and 37% with SHP (inorganic phosphorus < 1.3 mmol/l, n=136). The first model confirmed earlier findings that the risk of SHC is higher with increased parity (P ≤ 0.0001) and revealed a higher risk associated with high milk yield (P = 0.0005), high phosphorus intake (40–60 g/cow per day, OR = 3.5; ≥ 60 g/cow per day, OR = 7.3; P = 0.0003) and high vitamin D supply (≥ 19950 IU/cow per day, OR = 3, P = 0.007). The second model highlighted a greater risk of SHP with increasing parity (P = 0.03) and showed trends for the preventive effects of AcD (OR = 0.4, P = 0.07) and moderate amounts of phosphorus in the diet (OR = 0.4, P = 0.10). Overall, our results do not support the effectiveness of AcD in preventing SHC or SHP under field conditions examined here, probably resulting from insufficient diet acidification.

Effects of feeding 25-hydroxyvitamin D3 with an acidogenic diet during the prepartum period in dairy cows: Mineral metabolism, energy balance, and lactation performance of Holstein dairy cows

Our objective was to determine the effects of feeding 25-hydroxyvitamin D₃ [25(OH)D₃], or vitamin D₃ (cholecalciferol) on plasma, mineral, and metabolite concentrations, mineral balance, mineral excretion, rumination, energy balance, and milk production of dairy cows. We hypothesized that supplementing 3 mg/d of 25(OH)D₃ during the prepartum period would be more effective than supplementing vitamin D₃ at the National Research Council (2001) levels to minimize calcium imbalance during the transition period and improve milk production of dairy cows. Forty multiparous, pregnant nonlactating-Holstein cows were enrolled in this study. Body weight, body condition score, parity, and milk yield in the previous lactation (mean ± standard deviation) were 661 ± 59.2, 3.46 ± 0.35, 1.79 ± 0.87, and 33.2 ± 6.43 kg/d, respectively. Cows were enrolled into the blocks (n = 20 for each treatment) at 30 d of the expected day of calving to receive an acidogenic diet (373 g/kg of neutral detergent fiber and 136 g/kg of crude protein, dry matter basis; -110 mEq/kg) associated with the treatments: (1) control (CTRL), vitamin D₃ at 0.625 mg/d (equivalent to 25,000 IU of vitamin D₃/d) or (2) 25(OH)D₃ at 3 mg/d (equivalent to 120,000 IU of vitamin D₃/d). All cows were fed with the base ration for 49 d after calving. Blood samples were taken on d 7, 0, 1, 2, 21, and 42, relative to calving. No effect of treatment was observed for prepartum dry matter intake or body condition score. A trend for increase of ionized Ca was observed for the cows fed 25(OH)D₃, compared with the CTRL, but no effect of treatment was detected for total Ca or total P. Feeding 25(OH)D₃ increased colostrum yield. The plasmatic concentration of 25-hydroxyvitamin D₃ was increased with 25(OH)D₃ supplementation. 25-Hydroxyvitamin D₃ supplementation increased plasma glucose concentration at parturition. The postpartum dry matter intake was not influenced by treatments. Feeding 25(OH)D₃ increases milk yield, 3.5% fat-corrected milk, and energy-corrected milk and improves milk yield components in early lactation. Overall, these findings suggest that 25(OH)D₃ at 3 mg/d can improve the energy metabolism and lactation performance, compared with the current-feeding practice of supplementing vitamin D₃ at 0.625 mg/d.

Effect of vitamin D source and dietary cation-anion difference in peripartum dairy cows on calcium homeostasis and milk production

The objective of this experiment was to determine the effects of dietary vitamin D source on serum calcium (Ca), urinary Ca excretion, and milk production when fed in combination with a prepartum acidogenic negative dietary cation–anion difference (DCAD) diet. Nonlactating, pregnant multiparous cows (n = 15), balanced for breed (Holstein n = 9 and Jersey n = 6), and previous mature equivalent milk production, were assigned to one of three treatments (five cows/treatment), consisting of a control (PCH; positive DCAD, 8.9 mEq/100 g DM) and two negative DCAD diets (−15.4 mEq/100 g DM), one with vitamin D3 (cholecalciferol; NCH) and one with 25-hydroxyvitamin D3 (calcidiol; NCA; DSM nutritional products). The treatments were formulated to provide 1.95 mg/d of vitamin D and were fed 28 d prior to expected calving date. Delivery of vitamin D sources was accomplished by manufacture of a pellet and 2 kg of these pellets were individually fed simultaneously each day along with 2 kg of ground corn daily at 0800 hours. Negative DCAD treatments were formulated to provide 0.46 kg/d of Animate (Phibro Animal Health) and, if needed, additional Animate was top-dressed at each feeding to achieve a urine pH between 5.5 and 6.0 based on the previous day’s urine pH. Close-up cows had ad libitum access to chopped bermudagrass (Cynodon dactylon L.) hay and hay intake was measured using SmartFeed Pro systems (C-Lock Inc.; Rapid City, SD). Prepartum urine and serum samples were collected weekly and serum was collected 36, 48, and 72 h post-calving. Prepartum dry matter intake (DMI) as a percent of body weight was not (P = 0.66) affected by treatments. Cows fed NCH and NCA had greater (P = 0.02) prepartum serum Ca than PCH and tended to have greater urinary Ca excretions (P = 0.10). Average postpartum serum Ca (mg/dL) was greater (P = 0.05) for cows fed NCH (8.8) compared with PCH (7.8), whereas NCA (8.4) was numerically intermediate and not (P > 0.05) different from either of the other treatments. Postpartum DMI was not affected by treatment (P = 0.39). Daily milk yield (MY) (kg/d) was greatest (P < 0.01) for NCA (37.5) compared with the other treatments and NCH (34.1) was intermediate and greater than PCH (29.9). These results suggest that an acidogenic prepartum diet in combination with vitamin D was effective in maintaining peripartum serum Ca and the 25-hydroxy form of vitamin D improved MY compared with NCH in early lactation.

Randomized clinical trial to evaluate the effects of a prepartum cholecalciferol injection on postpartum serum calcium dynamics and health and performance in early-lactation multiparous dairy cows

The objectives of the present study were (1) to evaluate the effect of prepartum cholecalciferol treatment on serum Ca concentration during the first 10 d after calving and (2) to evaluate the effect of treatment on subsequent health and performance. Multiparous Holstein cows (n = 377) from one dairy farm were fed a negative dietary cation-anion difference diet (-31 mEq/kg of DM) for the last 21 d of gestation. On d 275, the animals were randomly assigned to a control or a treatment group. Cows in the control group were left untreated, and cows in the treatment group received an injection of 12 × 10⁶ IU of cholecalciferol intramuscularly on the day of enrollment. If treated cows did not deliver the calf within 6 d, they were reinjected with 10 × 10⁶ IU of cholecalciferol. Blood samples were drawn on 1, 2, 3, 5, 7, and 10 days in milk (DIM) and analyzed for serum Ca, P, and Mg concentrations. In a subsample of cows (50 control cows, 35 cows treated once with cholecalciferol, and 15 cows treated twice) serum haptoglobin, nonesterified fatty acids, β-hydroxybutyrate, and 25-hydroxycholecalciferol concentrations were analyzed on 1, 5, and 10 DIM. Binary data [retained placenta (RP), metritis] were analyzed using logistic regression models. Repeated measures ANOVA with first-order autoregressive covariance was performed to evaluate the treatment effect on milk yield over the first 10 test days after parturition, 25-hydroxycholecalciferol, serum Ca, P, Mg, β-hydroxybutyrate, nonesterified fatty acids, and haptoglobin concentrations. Cox proportional hazards were used to model the time to event outcomes (time to pregnancy within 200 d, culling until 300 DIM). After enrollment of 31.4% of cows and a preliminary analysis, adverse reactions became apparent, and the study was stopped. Cows treated with cholecalciferol had a greater risk of incurring RP and metritis. The adjusted mean incidences were 2.0%, 7.7%, and 4.0% for RP, and 21.6%, 39.3%, and 33.3% for metritis for control cows, cows treated once, and cows treated twice with cholecalciferol, respectively. Compared with control cows, cows injected once with 12 × 10⁶ IU of cholecalciferol produced less energy-corrected milk on the first (-3.76 kg) and second (-2.75 kg) test days, respectively. Cows injected twice with cholecalciferol (12 × 10⁶ IU of cholecalciferol and 10 × 10⁶ IU 1 wk later) had a reduced milk yield only at first test day (-3.80 kg). Treatment with cholecalciferol led to a significant increase in 25-hydroxycholecalciferol on d 1, 5, and 10 after calving. Serum Ca and P concentrations were significantly increased in cows treated with cholecalciferol, but serum Mg concentrations were significantly reduced. Haptoglobin concentrations were significantly increased on 5 DIM in cows injected once with 12 × 10⁶ IU of cholecalciferol. Although we observed no effect of treatment on culling until 300 DIM, time to pregnancy was delayed by 34 d in cows injected once with 12 × 10⁶ IU of cholecalciferol. In the present study, injection with 12 × 10⁶ IU of cholecalciferol had detrimental effects on health and milk production despite the beneficial effects on Ca homeostasis.

Effects of calcium supplementation, incomplete milking, and vitamin D3 injection on serum total calcium concentration during the first 24 hours after parturition in dairy cows fed an anionic diet during late gestation

OBJECTIVE

To evaluate various strategies for prevention of subclinical hypocalcemia (SH) during the first 24 hours after parturition in dairy cows.

ANIMALS

165 multiparous German Holstein cows from 1 herd.

PROCEDURES

All cows were fed a ration with a moderate dietary cation-anion difference (approx 0 mEq/100 g of dry matter; anionic diet) for the last 2 to 3 weeks of gestation. In the first part of a 2-part study, cows were randomly assigned to 1 of 4 treatment groups (no calcium supplementation [n = 30], oral administration of a calcium bolus alone [34] or in combination with IV administration of 500 mL of a calcium solution [34] or incomplete milking during the first 24 hours after parturition [34]). In part 2, cows in their fifth or greater parity were randomly assigned to receive vitamin D₃ (20,000 U/kg, IM; n = 15) 7 days before the predicted calving date or a control group (18). A calcium bolus was orally administered within 30 minutes after parturition to all cows of part 2. Serum total calcium (Ca_t) concentration was measured immediately after parturition and every 2 hours thereafter for 24 hours and compared among treatment groups. Subclinical hypocalcemia was defined as a Ca_t concentration < 2.00 mmol/L.

RESULTS

In part 1, the mean ± SD Ca_t concentration during the 24 hours after parturition for the IV-treated group (2.28 ± 0.42 mmol/L) was greater than that for the other 3 groups, each of which had a mean Ca_t concentration < 2.00 mmol/L. In part 2, the mean Ca_t concentration for the vitamin D₃-treated cows was greater than that for control cows and remained above 2.00 mmol/L for the duration of the observation period.

CONCLUSIONS AND CLINICAL RELEVANCE

Intramuscular administration of vitamin D₃ or IV administration of a calcium solution in combination with oral administration of a calcium bolus might alleviate SH during the first 24 hours after parturition in dairy cows fed an anionic diet during late gestation.

Meta-analysis-based estimates of efficiency of calcium utilisation by ruminants

The most abundant mineral in the body of animals is Ca, which has crucial importance for the regulation of various processes. The maintenance of Ca balance has become more challenging, especially in lactating ruminants, owing to the increased milk yields and thus Ca requirement. To determine the Ca requirement, factors such as Ca secretion via milk or Ca deposition in body tissues and conception products are summed up to the net Ca requirement. Nevertheless, dietary Ca cannot be completely utilised by the animal to cover the net Ca requirement, therefore a value for the efficiency of Ca utilisation is applied, which is the maximum proportion of Ca from the feed that the animal can use for covering the net requirement. However, current estimates for the efficiency of Ca utilisation are inconsistent. Therefore, the objective of the present meta-analysis was to estimate the efficiency of Ca utilisation for ruminants, considering the Ca supply of the animal. A data set of 223 observations was compiled from 37 studies, including data on cattle and small ruminants. Standardised Ca digestibility was calculated from data on Ca intake and faecal Ca excretion, corrected for faecal endogenous losses. Furthermore, a data subset on only lactating ruminants was created. For this subset, Ca excretion via faeces and urine and standardised Ca digestibility were related to the Ca supply of the animal. An exponential function was fitted to standardised digestibility data in response to Ca concentration in the diet and Ca supply, revealing that standardised Ca digestibility decreased with increasing dietary Ca concentration and Ca supply. The median for standardised Ca digestibility was 40%, with a remarkable variation between 9% and 88%. In response to Ca supply, faecal Ca excretion increased in a strong linear manner (slope = 0.76, R² = 0.96). Excretion of Ca via urine was very low even when Ca supply was very high. To conclude, Ca digestibility is a suitable indicator for the efficiency of Ca utilisation, since excessive Ca is almost completely excreted in faeces; however, Ca digestibility has to be determined at a Ca supply level below the requirement of the animal. To date, only very limited number of data have been reported for such supply conditions. Comparative studies using various Ca sources are suggested for future studies but should be conducted using a marginal Ca supply level.

Effects of 25-Hydroxyvitamin D3 and Oral Calcium Bolus on Lactation Performance, Ca Homeostasis, and Health of Multiparous Dairy Cows

Simple Summary

Subclinical hypocalcemia severely affects the lactation and health of dairy cows. Subclinical hypocalcemia is still a concern with cows after postpartum oral Ca; thus, the single treatment approach gradually has shifted to a multitreatment approach in terms of subclinical hypocalcemia. Supplementing 25-hydroxyvitamin D₃ could solve the problem of insufficient vitamin D₃ synthesis and blocked conversion in transition cows. The present study showed that feeding 25-hydroxyvitamin D₃ combined with oral calcium not only improved serum 25-hydroxyvitamin D₃ status and calcium homeostasis, but also had potential benefits on lactation performance and the health status during the transition period.

Abstract

Little information is available regarding the effect of supplementing 25-hydroxyvitamin D₃ during the transition period combined with a postpartum oral calcium bolus on Ca homeostasis. The objectives of the current study were to evaluate the effects of 25-hydroxyvitamin D₃ combined with postpartum oral calcium bolus on lactation performance, serum minerals and vitamin D₃ metabolites, blood biochemistry, and antioxidant and immune function in multiparous dairy cows. To evaluate the effects of 25-hydroxyvitamin D₃ combined with oral calcium, 48 multiparous Holstein cows were randomly assigned to one of four treatments: (1) supplementing 240 mg/day vitamin D₃ without a postpartum oral Ca bolus (control), (2) supplementing 240 mg/day vitamin D₃ with an oral Ca bolus containing 90 g of Ca immediately post-calving (Ca + VitD), (3) supplementing 6 g/day 25-hydroxyvitamin D₃ without an oral Ca bolus (25D), and (4) supplementing 6 g/day 25-hydroxyvitamin D₃ with an oral Ca bolus containing 90 g of Ca immediately post-calving (Ca + 25D). Lactation performance during the first 21 days was measured. Blood was collected at the initiation of calving and then 1, 2, 7, 14, and 21 days relative to the calving date. The yield of milk (0.05 < p < 0.10), energy-corrected milk (p < 0.05), 3.5% fat-corrected milk (p < 0.05), and milk protein (p < 0.05) were significantly higher in 25-hydroxyvitamin D₃-treated groups within 3 weeks of lactation than in vitamin D₃-treated cows. The iCa (p < 0.05) and tCa (p < 0.05) were higher in both Ca and 25D + Ca cows than in the control and 25D groups within 48 h. The concentrations of serum tCa (p < 0.05), tP (p < 0.05), and 25-hydroxyvitamin D₃ (p < 0.05) in 25D and 25D + Ca cows were higher than those in control and Ca cows within 21 days postpartum. Feeding 25-hydroxyvitamin D₃ also showed a lower concentration of malondialdehyde (p < 0.05), interleukin 6 (p < 0.05), and tumor necrosis factor-alpha (TNF-α) (p < 0.05), as well as a higher concentration of alkaline phosphatase (p < 0.05), total antioxidant capacity (p < 0.05), and immunoglobulin G (p < 0.05) than vitamin D₃. Supplementing Ca bolus also showed lower concentrations of alanine transaminase (p < 0.05) and TNF-α (p < 0.05). In conclusion, supplementing 25-hydroxyvitamin D₃ during the transition period combined with a postpartum oral calcium bolus improved lactation performance, Ca homeostasis, and antioxidant and immune function of medium-production dairy cows within 21 days postpartum.

Effect of 25-hydroxyvitamin D3 during prepartum transition and lactation on production, reproduction, and health of lactating dairy cows

We hypothesized that feeding 25-hydroxyvitamin D₃ [25-(OH)D₃] during lactation and prepartum in conjunction with negative dietary cation-anion difference diets would improve milk production, increase the probability of pregnancy, and reduce the incidence of postcalving diseases. Cows from 4 dairies with prepartum transition diets negative in dietary cation-anion difference were used in 2 randomized cohort experiments. In Experiment 1 (Exp. 1), cows were assigned to control [CON; n = 645; no 25-(OH)D₃] or treatment [TRT; n = 537; 2 mg/d of 25-(OH)D₃ from ∼21 d prepartum to parturition and 1 mg/d in lactation] groups at ∼21 d prepartum. Cows were monitored for weekly milk yield, milk composition every 60 d, and health and reproductive measures. In Experiment 2 (Exp. 2), cows (n = 2,064; median 147 d in milk) were assigned to 4 groups and monitored for the same measures as in Exp. 1 to the end of that lactation (L1), the subsequent transition (∼21 d prepartum to parturition), and the next lactation (L2). Groups were as follows, with the amount of 25-(OH)D₃ fed (mg/d) indicated in parentheses for L1, transition, and L2, respectively: (A) control-control (CON-CON; 0-0-0), (B) treatment-treatment (TRT-TRT; 1-2-1), (C) control-treatment (CON-TRT; 0-2-1), and (D) treatment-control (TRT-CON; 1-0-0). For L1, a total of 1,032 cows entered the control groups A or C and a total of 1,032 cows in groups B or D. The number of cows in groups A to D that entered L2 was 521, 523, 273, and 248, respectively. Blood calcium, phosphorus, and 25-(OH)D₃ concentrations were measured from 17 cows/group at 5 times. In Exp. 1, TRT cows had 0.2 lower log somatic cell count than CON cows (4.21 ± 0.045 vs. 4.01 ± 0.050, respectively) and multiparous TRT cows had 41 ± 23% higher probability of pregnancy/day than multiparous CON cows, resulting in a 22-d median decrease in time to pregnancy. Primiparous TRT cows had 1.67 ± 0.40 times greater odds of mastitis/day than primiparous CON cows. In Exp. 2 TRT-TRT cows had between 16 and 29% lower probability to be bred/day than other groups. Multiparous CON-CON and TRT-CON cows had 20 ± 8% and 30 ± 17% greater probability of pregnancy, respectively, than multiparous TRT-TRT cows. Serum calcium concentrations were not affected by group, but phosphorus and 25-(OH)D₃ concentrations were highest in the TRT-TRT cows. The study provides further insights into the use of 25(OH)D₃ in transition and lactation.

Effect of antepartum vitamin D3 (cholecalciferol) and postpartum oral calcium administration on serum total calcium concentration in Holstein cows fed an acidogenic diet in late gestation

Several strategies are available to control periparturient hypocalcaemia in dairy cows. Three complementary strategies were applied in this study: feeding a low DCAD (acidogenic) ration during late gestation, oral vitamin D₃ (cholecalciferol) administration in late gestation, and oral Ca administration immediately after parturition. Multiparous Holstein cows (n = 240) were fed an acidogenic ration in late gestation and randomly assigned to one of three treatment groups. Group A (n = 80) were fed the acidogenic diet without supplementary Ca or cholecalciferol. Group Ca + A (n = 80) received 50 g of Ca as an oral bolus at calving and 12 h later. Group D₃ + Ca + A (n = 80) were administered 3 mg of cholecalciferol orally each day starting 3 to 5 days before the anticipated calving date and 50 g of Ca as an oral bolus at calving and 12 h later. Blood and urine samples were obtained periodically from a random subset of 20 cows in each group from day 5 antepartum to day 21 postpartum and selected analytes measured. Data was analyzed using mixed models analysis. Serum Ca concentrations in group D₃ + Ca + A were higher 12 h before and at parturition, compared to the two other groups. Oral Ca administration transiently increased mean serum Ca concentrations at 6 h after treatment initiation in groups D₃ + Ca + A and Ca + A. We conclude that daily oral administration of 3 mg of cholecalciferol for up to 5 days before calving, combined with feeding an acidogenic ration in late gestation and oral Ca immediately after parturition, provided the highest periparturient serum Ca concentrations.

Biochemical Bone Markers During the Transition Period Are Not Influenced by Parenteral Treatment With a High Dose of Cholecalciferol but Can Predict Milk Fever in Dairy Cows

Despite being studied extensively, there are still many knowledge gaps in milk fever prevention and it is still a prevalent disease. Various interventions have been used in its prevention; however, none has proven to be entirely effective. The study aimed to assess the effectiveness of high dose vitamin D₃ parenteral (intramuscularly) administration and the mechanism of its action by studying blood minerals and biochemical bone markers. Further, we assessed the potential of biochemical bone markers, measured in the close-up dry period, as predictors of clinical milk fever after calving. The study was conducted on 56 high yielding, clinically healthy dairy cows, before their 4th or higher lactation. They were divided into three groups based on season (summer and winter) and administration (vitamin D). The winter group was considered as the control group. Cows (n = 13) were parenterally administered a single dose of 10 million IU of vitamin D₃ (DUPHAFRAL® D3) ranging between 10 and 2 days before calving (median = 3 days). Each cow was blood sampled once during four sampling period ranges: ~1 month before calving, 10 to 2 days before calving, 12–48 h after calving and 10–20 days after calving. The samples were analyzed for blood minerals, bone specific alkaline phosphatase (bALP) and C-terminal telopeptide of type I collagen (CTx), alkaline phosphatase, and estradiol. Values were compared between samplings and groups. A receiver operating characteristic (ROC) analysis and logistic regression were used to assess the diagnostic accuracy of biochemical bone markers in predicting milk fever. In this study high dose vitamin D₃ supplementation did not statistically reduced the incidence of milk fever (milk fever incidences were 15.4, 39.1, and 25% in the vitamin D, winter and summer groups, respectively). A significant effect of vitamin D₃ administration on blood minerals or biochemical bone markers was not found at any sampling. We found that the use of biochemical bone markers in the close-up dry period to predict clinical milk fever was applicable only in the winter (housed) group. The area under the curve (AUC) for bALP was 0.804 and 0.846 for CTx using ROC analysis. The bALP curve had the best ratio at the cut-off point 13.85 U/L with 90% sensitivity and 64.3% specificity. While CTx had the ratio of 90% sensitivity and 78.6% specificity at the cut-off point 0.149 ng/mL. Close-up dry dairy cows with CTx ≥0.121 ng/mL had a 3.8 times higher chance of succumbing to milk fever. We were unable to prove that high dose vitamin D₃ parenteral administration is a viable technique for milk fever prevention. Biochemical bone markers are a promising tool for predicting milk fever; however, further studies are needed to confirm their clinical use.

Boron supplementation in peripartum Murrah buffaloes: The effect on calcium homeostasis, bone metabolism, endocrine and antioxidant status

BACKGROUND

Calcium homeostasis and immuno-endocrine system undergoes drastic changes in peripartum dairy animals and failure to adapt these physiological changes causes major impact on animal health as well as productivity. Boron (B), a newer trace element, influences calcium (Ca), phosphorus (P) and magnesium (Mg) metabolism as well as immune system by manipulating several hormones or enzyme systems. Present study was conducted to determine the effect of dietary B supplementation on Ca homeostasis, bone metabolism, endocrine and antioxidant status in peripartum Murrah buffaloes.

METHODS

Thirty advanced pregnant Murrah buffaloes (8th month pregnant) were allocated into three groups based on their most probable producing ability (MPPA) and parity (n = 10 in each group) viz. B0, B200 and B400 and supplemented with 0, 200 and 400 ppm of B in the form of boric acid. Blood samples were collected at periodic intervals (-45, -30, -21, -15, -7, 0, 7, 15, 30, 60, 90 and 120 day relative to expected date of calving) and analysed for minerals concentration, hormonal profile, bone health biomarkers and antioxidant enzymes.

RESULTS AND CONCLUSION

Boron supplementation at 200 and 400 ppm increased (p < 0.05) plasma Ca, Mg and osteocalcin (OCN) concentration during postpartum stage. Higher (p < 0.05) levels of plasma 25-hydroxy vitamin D₃ were observed in both B supplemented groups as compared to B unsupplemented group irrespective of physiological stages. Plasma parathyroid hormone (PTH) and cortisol levels were lower (p < 0.05) in both B supplemented groups than B unsupplemented group, especially during postpartum stage. Whereas, plasma ferric reducing total antioxidant power (FRAP) activity was found to be higher (p < 0.05) in B supplemented groups as compared to B unsupplemented group. Furthermore, antioxidant enzymes (erythrocytic superoxide dismutase; SOD, catalase, glutathione peroxidase; GPx), plasma level of total immunoglobulins (TIg), bone specific alkaline phosphatase (BALP) and tartrate resistant acid phosphatase (TRAP) remained unaffected by dietary B supplementation. Overall, it can be concluded that supplementation of B at 200 ppm in the diet of peripartum Murrah buffaloes helped to induce metabolic adaptations for improving Ca homeostasis, bone metabolism and antioxidant status without much additional benefits at higher level used in the present study.

Calcinosis in a roe deer fawn (Capreolus capreolus) in northern Germany

Background

Calcinosis has been reported for a broad range of different animals. Causes for calcinosis include metabolic disorders due to kidney failure, intoxication with calcinogenic plants, or iatrogenic overdose of vitamin D. Especially young animals seem to be very susceptible to developing calcinosis. Currently, however, there is a lack of information on calcinosis in wildlife.

Case presentation

The following case report describes a roe deer fawn admitted to a clinic due to general weakness and myiasis. Plasma levels for creatinine, urea and phosphate were highly elevated, whereas the total calcium level was decreased. Necropsy revealed calcinosis due to calcification in many organs. The reason for calcinosis in this particular case might be kidney failure. Plasma samples from other hunted roe deer fawns also showed high phosphate levels.

Conclusions

Roe deer fawns might be susceptible to calcinosis due to high plasma phosphate, which could be a result of kidney failure or different feed. Further research into calcium and phosphate homeostasis in roe deer is necessary.

Dietary phosphorus restriction affects bone metabolism, vitamin D metabolism and rumen fermentation traits in sheep

Homeostasis of calcium (Ca) and phosphate (P_i ) is maintained by a concerted interplay of absorption and reabsorption via the gastrointestinal tract and the kidney and by storage and mobilization from the bone regulated mainly by parathyroid hormone (PTH), 1,25-dihydroxycholecalciferol and calcitonin. The present study aimed at characterizing the effects of dietary P restriction on bone, vitamin D metabolism and rumen fermentation traits reflecting the endogenous P cycle maintaining the ruminal P supply for microbial metabolism. The experiments were done in eleven female, non-pregnant, non-lactating four- to nine-year-old Black Headed Mutton sheep allotted to two feeding groups: "P-restricted" (0.11% P/kg DM and 0.88% Ca/kg DM) and "Control" (0.38% P/kg DM and 0.88% Ca/kg DM). Dietary P restriction did not lead to hypophosphataemia, probably due to a compensation by bone mobilization, demonstrated by increased serum concentrations of a resorption marker and altered gene expression in bone tissue. In addition, the RNA expression of fibroblast growth factor 23, a bone-derived factor involved in the regulation of vitamin D metabolism, was significantly reduced with dietary P restriction. Furthermore, several genes related to vitamin D metabolism and plasma concentrations of 1,25-(OH)₂ D were associated with serum concentrations of phosphate (P_i ). In the parotid gland, the expression of the P_i transporter NaPi2b was negatively associated with serum P_i and positively with parathyroid PTH expression. Although P_i concentrations in saliva and the gastrointestinal tract were significantly reduced, we found no adverse effects of the P-restricted ration on the production of short chain fatty acids, but slight differences in the production of butyrate as well as its relationship to rumen P_i and ammonia concentrations that might indicate an impact on ruminal fermentation.

Review: Regulation of gastrointestinal and renal transport of calcium and phosphorus in ruminants

In comparison to monogastric animals, ruminants show some peculiarities in respect to the regulation of mineral homeostasis, which can be regarded as a concerted interplay between gastrointestinal absorption, renal excretion and bone mobilisation to maintain physiological Ca and phosphate (Pi) concentrations in serum. Intestinal absorption of Ca or Pi is mediated by two general mechanisms: paracellular, passive transport dominates when luminal Ca or Pi concentrations are high and transcellular. The contribution of active transport becomes more important when dietary Ca or Pi supply is restricted or the demand increased. Both pathways are modulated directly by dietary interventions, influenced by age and regulated by endocrine factors such as 1,25-dihydroxyvitamin D3. Similar transport processes are observed in the kidney. After filtration, Ca and Pi are resorbed along the nephron. However, as urinary Ca and Pi excretion is very low in ruminants, the regulation of these renal pathways differs from that described for monogastric species, too. Furthermore, salivary secretion, as part of endogenous Pi recycling, and bone mobilisation participate in the maintenance of Ca and Pi homeostasis in ruminants. Saliva contains large amounts of Pi for buffering rumen pH and to ensure optimal conditions for the rumen microbiome. The skeleton is a major reservoir of Ca and Pi to compensate for discrepancies between demand and uptake. But alterations of the regulation of mineral homeostasis induced by other dietary factors such as a low protein diet were observed in growing ruminants. In addition, metabolic changes, for example, at the onset of lactation have pronounced effects on gastrointestinal mineral transport processes in some ruminant species. As disturbances of mineral homeostasis do not only increase the risk of the animals to develop other diseases, but are also associated with protein and energy metabolism, further research is needed to improve our knowledge of its complex regulation.

A Pilot Study To Evaluate The Effect Of A Novel Calcium And Vitamin D-Containing Oral Bolus On Serum Calcium Levels In Holstein Dairy Cows Following Parturition

Background

The initiation of lactation challenges the ability of the modern lactating cow to maintain calcium homeostasis, and typically results in a drop in blood calcium levels, leading to mobilization of calcium reserves from skeletal stores. As such, the recommendation to provide supplemental calcium at parturition to older cows has become an industry-standard practice.

Methods

Mature cows were treated at calving and 12 hrs later with either the novel calcium bolus (NB) or a commercially available calcium bolus (CB). Blood was collected from animals at 0, 1, 6, 12, 13, and 24 hrs following calving, and the resulting serum samples were analyzed.

Results

Overall, there was no statistical difference between the NB and CB groups for blood calcium levels within the first 24 hrs following parturition (P = 0.50). Cows in both groups experienced a significant increase in serum calcium by 1 hr after parturition; however, this increase was not sustained through subsequent sampling times.

Conclusion

This pilot study demonstrates that both boluses have a similar effect in the elevation of blood calcium.

Administration of Vitamin D Metabolites Affects RNA Expression of Xenobiotic Metabolising Enzymes and Function of ABC Transporters in Rats

From studies on different species and in cell culture systems, it has been suggested that vitamin D metabolites might affect the metabolism and elimination of xenobiotics. Although most studies performed on rodents and cell cultures report an upregulation of respective enzymes and transporters, data from the literature are inconsistent. Especially results obtained with sheep differ from these observations. As vitamin D metabolites are widely used as feed additives or therapeutics in livestock animals, we aimed to assess whether these differences indicate species-specific responses or occurred due to the very high dosages used in the rodent studies. Therefore, we applied treatment protocols to rats that had been used previously in sheep or cattle. Forty-eight female rats were divided into three treatment and corresponding placebo groups: (1) a single intraperitoneal injection of 1,25-(OH)2D3 or placebo 12 h before sacrifice; (2) daily supplementation with 25-OHD3 by oral gavage or placebo for 10 days; and (3) a single intramuscular injection of vitamin D3 10 days before sacrifice. In contrast to a previous study using sheep, treatment of rats with 1,25-dihydroxyvitamin D3 did not result in an upregulation of cytochrome P450 3A isoenzymes (CYP3A), but a decrease was found in hepatic and intestinal expressions. In addition, a downregulation of P-glycoprotein (P-gp) and breast cancer resistance protein was found in the brain. Taken together, the stimulating effects of vitamin D metabolites on the expression of genes involved in the metabolism and elimination of xenobiotics reported previously for rodents and sheep could not be reproduced. In contrast, we even observed a negative impact on the expression of CYP3A enzymes and their most important regulator, the pregnane X receptor. Most interestingly, we could demonstrate an effect of treatment with 25-hydroxyvitamin D3 and vitamin D3 on the functional activity of ileal P-glycoprotein (P-gp) using the Ussing chamber technique.

Metabolic and production responses to calcidiol treatment in mid-lactation dairy cows

The study of vitamin D in cattle has often focussed on its role in calcium and mineral metabolism. However, there is evidence of a wider role for vitamin D in bone and energy metabolism. Two studies were conducted to explore relationships between calcidiol supplementation, blood minerals and metabolites in mid-lactation dairy cows. In Experiment 1, a dose-response study was conducted in which 25 mid-lactation cows were fed one of five supplementary calcidiol doses (0, 0.5, 1, 2 or 4 mg calcidiol/day) for 30 days, with blood samples taken every 10 days. Increasing calcidiol dose increased plasma calcidiol (P=0.001), 24,25-(OH)2-D3 (P=0.001) and serum phosphate (P=0.003) in a curvilinear manner, increased and then decreased plasma 25-OH-D2 (P=0.004) and linearly increased 3-epi 25-OH-D3 (P=0.001) and milk calcidiol concentrations (P=0.001). Calcidiol supplementation did not affect milk yield or composition, bodyweight or condition score. In Experiment 2, relationships between blood calcidiol and mineral and metabolite concentrations over time were explored using time-series analysis. Ten mid-lactation cows were fed either 0 or 0.5 mg calcidiol/day for 27 days, with blood samples taken every 3 days. Feeding calcidiol increased plasma calcidiol (P=0.001), 24,25-OH-D3 (P=0.038), and insulin (P=0.046), but decreased 25-OH-D2 (P=0.008) concentrations. Positive associations were identified between blood calcidiol and concentrations of other metabolites, including cholecalciferol, calcium, osteocalcin, glucose, insulin, non-esterified fatty acids, β-hydroxybutyrate, cholesterol, magnesium, phosphorus and total protein at varying lags (±0, 3 or 6 days), while negative relationships were identified between calcidiol and 24,25-(OH)2-D3, and phosphorus 3 days later. Importantly, strong positive associations between calcidiol and indicators of energy metabolism were identified. Overall, these experiments provide support for a positive effect of calcidiol treatment on dairy cow metabolism.

Associations between bone and energy metabolism in cows fed diets differing in level of dietary cation-anion difference and supplemented with cholecalciferol or calcidiol

Bone-derived hormones play an important role in metabolism. This study examined the hypothesis that interactions between bone and energy metabolism, particularly those involving osteocalcin, are present in dairy cattle and have feedback mechanisms over time. Associations between metabolites in blood were examined in 32 Holstein cows blocked by parity and milk yield and randomly allocated to diets containing either 0.27 mg/kg dry matter (DM) calcidiol or cholecalciferol for an anticipated intake of 3 mg/d (120,000 IU/d) at 11 kg of DM, and positive (+130 mEq/kg DM) or negative (-130 mEq/kg DM) dietary cation-anion difference (DCAD) from 252 d of gestation to calving. Blood was sampled every 3 d, from 9 d prepartum to 30 d postpartum, and plasma concentrations of vitamin D₃, 25-hydroxyvitamin D₃, adiponectin, C-telopeptide of type 1 collagen (CTX1), glucose, insulin-like growth factor 1 (IGF1), insulin, undercarboxylated osteocalcin (uOC), and carboxylated osteocalcin (cOC) were determined. Feeding calcidiol compared with cholecalciferol increased plasma concentrations of 25-hydroxyvitamin D₃ pre- (264.2 ± 8.0 vs. 61.3 ± 8.0 ng/mL) and postpartum (170.8 ± 6.2 vs. 51.3 ± 6.2 ng/mL) but decreased concentrations of vitamin D₃ pre- (1.2 ± 0.6 vs. 14.5 ± 0.6 ng/mL) and postpartum (1.9 ± 0.4 vs. 3.2 ± 0.6 ng/mL). Prepartum, cows fed the negative DCAD diet had reduced concentrations of vitamin D₃ and glucose compared with cows fed a positive DCAD. The combination of negative DCAD and cholecalciferol reduced IGF1 concentrations prepartum. The DCAD treatment had no effect on postpartum concentrations of metabolites. Nulliparous cows had increased concentrations of OC, CTX1, IGF1, glucose, and insulin compared with parous cows. Time series analysis identified associations between metabolites on the same day and over 3-d lags up to ±9 d that suggest feedback between 25-hydroxyvitamin D₃ and vitamin D₃ in the negative lags, indicating that 25-hydroxyvitamin D₃ may exert feedback on vitamin D₃ but not vice versa. We found evidence of a feedback mechanism between vitamin D₃ and IGF1, with positive effect size (ES) on the same day and 3 d later, and negative ES 9 d later, that was more evident in cholecalciferol-fed cows. This suggests an important role of IGF1 in integrating bone metabolism with energy and protein metabolic pathways. Evidence of feedback was found between uOC and particularly cOC with IGF1, with positive ES on the same day but negative ES 6 d before and 6 d after. An association between uOC or cOC and IGF1 has not been previously identified in cattle and suggests that both uOC and cOC may have marked biological activity. Associations between OC and insulin identified in mice were not observed herein, although associations between OC and glucose were similar to those between IGF1 and glucose, supporting associations between glucose, OC, and IGF1. We provide further statistical evidence of crosstalk between vitamin D compounds, bone hormones, and energy metabolism in cattle. In particular, associations between uOC or cOC and IGF1 may provide links between prepartum diets and observations of prolonged increases in milk production and allow better control of peripartum metabolism.

Effect of dietary vitamin D3 and 25-hydroxyvitamin D3 supplementation on plasma and milk 25-hydroxyvitamin D3 concentration in dairy cows

Milk enriched with vitamin D by supplementing dairy cow diets could provide a valuable dietary source of vitamin D, but information on the feasibility of this approach is limited. In the current study, the effects of supplementing dairy cows with either vitamin D₃ or 25(OH)D₃ over the transition/early lactation period on plasma and milk vitamin D concentrations were compared. Sixty dairy cows were randomly allocated to 1 of 4 dietary treatments from 14 d precalving to 56 d postcalving. Treatments were a control diet (control) for both precalving and postcalving periods containing 0.625 mg/d of vitamin D₃; a precalving diet supplemented with 6 mg of 25(OH)D₃/d, but with a postcalving diet matching that of the control diet [25(OH)D₃ precalving]; the control diet precalving but with the postcalving diet supplemented with 2 mg of vitamin D₃/d (D₃max), and the control diet precalving but with the postcalving diet supplemented with 1.5 mg of 25(OH)D₃/d [25(OH)D₃ postcalving]. No treatment effect on milk yield, composition or 25(OH)D₃ concentration was observed. However, an interaction was observed of treatment and time for plasma 25(OH)D₃ concentration; this increased within 2 wk of supplementation for the 25(OH)D₃ precalving treatment (peaking just after calving, 202 ng/mL), whereas that of the 25(OH)D₃ postcalving group had a slower response following supplementation, continuing to increase at 56 d. Correlations were observed between plasma and milk 25(OH)D₃ concentrations at d 4 and 14 of lactation, but not at later sampling times. The D₃max treatment did not increase 25(OH)D₃ concentration in plasma or milk. Overall, results from this study indicate that supplemental 25(OH)D₃ is an effective means of enhancing dairy cow plasma 25(OH)D₃ concentrations compared with vitamin D₃ supplementation, but not necessarily milk concentrations.

Nutritional strategies in ruminants: A lifetime approach

This review examines the role of nutritional strategies to improve lifetime performance in ruminants. Strategies to increase ruminants' productive longevity by means of nutritional interventions provide the opportunity not only to increase their lifetime performances and their welfare, but also to decrease their environmental impact. This paper will also address how such nutritional interventions can increase herd efficiency and farm profitability. The key competencies reviewed in this article are redox balance, skeletal development and health, nutrient utilization and sustainability, which includes rearing ruminants without antibiotics and methane mitigation. While the relationships between these areas are extremely complex, a multidisciplinary approach is needed to develop nutritional strategies that would allow ruminants to become more resilient to the environmental and physiological challenges that they will have to endure during their productive career. As the demand of ruminant products from the rapidly growing human world population is ever-increasing, the aim of this review is to present animal and veterinary scientists as well as nutritionists a multidisciplinary approach towards a sustainable ruminant production, while improving their nutrient utilization, health and welfare, and mitigation of their carbon footprint at the same time.

A Dairy Herd Case Investigation with Very Low Dietary Cation-Anion Difference in Prepartum Dairy Cows

During the periparturient period, subclinical hypocalcemia (total plasma Ca concentration <2.0 mmol/l) is a potential problem for the dairy cow; consequently, its prevention is essential for success of fertility and productive performance. Dietary cation–anion difference (DCAD) has been defined as the difference in milliequivalents of cations (Na, K) and anions (Cl, S) per kilogram of dry matter (DM) and has a direct impact on blood acid–base metabolism. Diets rich in K and Na induce metabolic alkalosis, interfering with tissue sensitivity to parathyroid hormone, and diets rich in Cl and S (anionic salts) cause metabolic acidosis, reducing the risk of hypocalcemia. Consequently, the use of anionic salts has become a popular method to prevent hypocalcemia in dairy cattle. Monitoring diets with anionic salts can be done by measuring urine pH, with optimal values between 6.2 and 6.8 for Holstein cows. The objective of this report is to present a herd case investigation involving a dairy farm feeding a very low DCAD (−143 mEq/kg DM), expecting improved Ca homeostasis. The diet of −143 mEq/kg (urine pH 5.2–5.8) was changed to a diet with −53 mEq/kg DM (urine pH 6.2–6.8). Blood samples were taken at the time of calving for 10 cows that calved before and then for 10 cows that calved after changing the diet. Cows with extremely low DCAD had Ca concentrations of 2.11 ± 0.22 mmol/l and cows with a more moderated DCAD, 2.11 ± 0.16 mmol/l (P > 0.05). Several other blood metabolites (P, Mg, Na, K, Cl, albumin, globulins, blood urea nitrogen, creatinine, and GGT) were also similar between groups. This very low DCAD during the prepartum period may severely compromise animal physiology unnecessarily, with little advantage over normal calcium concentrations at parturition, when compared with a less negative DCAD (−53 mEq/kg DM). Feeding a less negative DCAD ration (−53 mEq/kg DM) did not decrease plasma Ca levels right after parturition compared to a DCAD ration of −143 mEq/kg DM, reinforcing the lack of benefit of a more negative DCAD.

Influence of 25-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D3 on expression of P-glycoprotein and cytochrome P450 3A in sheep

In order to improve calcium and phosphorus balance, beef cattle and dairy cows can be supplemented with vitamin D. However, different vitamin D metabolites have been shown to increase expression of P-glycoprotein (P-gp, MDR1, ABCB1) and cytochrome P450 3A (CYP3A) in rodents as well as in cell culture systems. As such interferences might have an impact on pharmacokinetics of some drugs widely-used in veterinary medicine, we investigated the expression of P-gp, CYP3A, vitamin D receptor (VDR), pregnane X receptor (PXR) and retinoid X receptor α (RXRα) in sheep either treated orally with 6μg/kg body weight (BW) 25-hydroxyvitamin D₃ (OHD₃) for ten days before sacrifice or 12h after intravenous injection of 0.5μg/kg BW 1,25-dihydroxyvitamin D₃ (1,25- (OH)₂D₃). Down-regulation of ruminal, jejunal and hepatic, but not renal P-gp could be found with 25-OHD₃ supplementation. Interestingly, this effect on P-gp was not observed in tissues from 1,25-(OH)₂D₃-treated sheep. In contrast, 1,25-(OH)₂D₃ induced a significant up-regulation of renal and jejunal CYP3A expression, while 25-OHD₃ had no impact. Renal expression of VDR and PXR was also increased by treatment with 1,25-(OH)₂D₃, while jejunal PXR expression was only stimulated in sheep supplemented with 25-OHD₃. Either treatments increased renal, but not ruminal, jejunal or hepatic expression of RXRα. These results demonstrate that the impact of large doses of vitamin D metabolites on different target organs and potential interactions with other medications should be further investigated in vitro and in vivo to understand the effects of vitamin D metabolites on metabolism and excretion pathways in livestock.

Effect of feeding 25-hydroxyvitamin D3 with a negative cation-anion difference diet on calcium and vitamin D status of periparturient cows and their calves

Holstein cows (>1 gestation) were fed 1 of 3 diets during the last 13 d of gestation (ranged from 22 to 7 d). The control diet (16 cows) was formulated to provide 18,000 IU/d of vitamin D3 and had a dietary cation-anion difference (DCAD) of 165mEq/kg (DCAD=Na + K - Cl - S). The second diet (DCAD + D) provided the same amount of vitamin D3 but had a DCAD of -139mEq/kg (17 cows). The third diet (DCAD + 25D) had no supplemental vitamin D3 but provided 6mg/d of 25-(OH) vitamin D3 [25-(OH)D3] with a DCAD of -138mEq/kg (20 cows). Diets were fed until parturition and then all cows were fed a common lactation diet that contained vitamin D3. Negative DCAD diets reduced urine pH, with the greatest decrease occurring with the DCAD + D treatment. Urinary Ca excretion was greatest for cows fed DCAD + 25D followed by cows fed DCAD + D. Urinary pH was negatively correlated with urinary excretion of Ca for cows fed DCAD + D. No such correlation was observed with the DCAD + 25D treatment because substantial excretion of urinary Ca occurred at moderate urinary pH values for that treatment. Cows fed DCAD + 25D had greater serum concentrations of 25-(OH)D3 than other treatments from 5 d after supplementation started through 7 d in milk. Concentrations of 1,25-(OH)2D3 in serum were greatest in DCAD + 25D cows starting at 2 d before calving and continued through 7 d in milk. Serum Ca concentrations 5 d before calving were greatest for cows fed DCAD + 25D, but at other time points before and after parturition treatment did not affect serum Ca. Incidence of clinical hypocalcemia was not statistically different between treatments, but cows fed DCAD + 25 had the highest incidence rate (12.5, 0, and 20% for control, DCAD + D, and DCAD + 25D). Calves born from cows fed DCAD + 25D had greater concentrations of 25-(OH)D3 in serum at birth than calves from other treatments (before colostrum consumption), but concentrations were similar by 3 d of age. Concentrations of 25-(OH)D3 in colostrum and transition milk were increased by feeding DCAD + 25D, but by 28 d in milk treatment effects no longer existed. Overall, feeding 25-OH vitamin D with a negative DCAD diet increased vitamin D status of the cow and her newborn calf but had minimal effects on calcium status and did not have positive effects on the incidence of hypocalcemia.

Differences in peripartal plasma parameters related to calcium homeostasis of dairy sheep and goats in comparison with cows

Recently it has been demonstrated that there are differences between sheep and goats in respect to adaptation to a calcium-restricted diet. It was the aim of the present study to evaluate whether species-specific peculiarities also occur when calcium homoeostasis is challenged by lactation. Therefore, we investigated the time courses of plasma parameters related to calcium homoeostasis (calcium, phosphate, calcitriol, the bone resorption marker CrossLaps® and the bone formation marker osteocalcin) during the transition period in multiparous animals of both species and compared the results to data from a former study carried out with dairy cows. As in cows, plasma calcium and the ratio of bone formation to bone resorption decreased at parturition in goats while plasma calcitriol increased. On day 10 post partum the bone parameters of goats reached prepartum values again, which was not the case in cows. Sheep were found to experience a challenge of calcium homoeostasis already 10 d before parturition, reflected by a very low ratio of bone formation to bone resorption, which was not accompanied by an increase in plasma calcitriol. Additionally, sheep and goats which had been in milk for 3 months were sampled, dried-off and sampled again 6 weeks later. In dried-off animals there were no detectable differences in parameters of bone metabolism. In conclusion we could show that the contribution of bone mobilisation to the compensation for the enhanced calcium demand due to lactation differs between the three ruminant species.

Suplemento mineral aniônico para vacas no periparto: parâmetros sanguíneos, urinários e incidência de patologias de importância na bovinocultura leiteira

A fim de avaliar o efeito do suplemento mineral aniônico sobre parâmetros sanguíneos, urinários e incidência de hipocalcemia e retenção de placenta, dezoito vacas de aptidão leiteira com grau de sangue 7/8 Holandesa preta e branca, com 440-620 kg e 5-10 anos, foram divididas com delineamento em blocos em função da ordem de parto em dois grupos: controle (BCAD=46,38mEq/kg de MS) e tratamento (com adição de suplemento mineral aniônico e BCAD = -249,28mEq/kg de MS). Foram monitorados níveis de cálcio total e pH na urina e soro sanguíneo; TCO2, pCO2, HCO3, excesso de base, cálcio ionizado, Na, K, Se no sangue; escore de condição corporal, hematócrito e hemoglobina. Os dados sanguíneos, urinários e ECC foram submetidos ao Proc Means do SAS (2000) com análise de variância a 5% e teste de Tukey e a incidência de retenção de placenta analisada por Mann-Whitney (P<0,07) e a concentração sérica de Se por teste t de Student (P<0,05), ambos pelo GraphPad Prism 5.0. O suplemento mineral aniônico diminuiu os valores de TCO2, pCO2, HCO3 e EB no sangue com menor perda de peso, mas a variação de pH e cálcio foi restrita ao tempo. O suplemento mineral aniônico não provocou leve acidose metabólica desejada e, consequentemente, não preveniu a hipocalcemia. Contudo, por apresentar Se em sua composição, proporcionou maior concentração deste micronutriente no soro e contribuiu para menor retenção de placenta.

Is the metabolism of 25-hydroxyvitamin D3 age-dependent in dairy cows?

It has recently been demonstrated that prepartum administered 25-hydroxyvitamin D3 (25-OHD3) is a promising candidate to assist the maintenance of peripartal calcium homeostasis in dairy cows. Since the incidence of peripartal hypocalcemia and the reported beneficial effects of the treatment are both associated with the lactation number, we investigated pharmacokinetic aspects of 25-OHD3 related to the age of dairy cows. The daily oral administration of 3mg 25-OHD3 in rapeseed oil as well as a treatment with 4 and 6mg included in the feed during the last eight to ten days of gestation resulted in linear dosage- and age-dependent increases in plasma 25-OHD3. After parturition the administration was stopped and blood samples were taken to calculate the plasma half-life. Irrespective of the supplemented dosage, cows starting the 2nd lactation showed a significantly longer plasma half-life of 25-OHD3 than cows starting the 3rd or higher lactation. Age-dependent differences in the increase of plasma 25-OHD3 could already be found before parturition when calcium homeostasis was not yet significantly challenged. Additionally, no correlations between plasma half-life of 25-OHD3 and 1,25-dihydroxyvitamin D3, PTH or the bone resorption marker CrossLaps were observed after parturition. Thus we conclude that the influence of the lactation number on the pharmacokinetics of 25-OHD3 is related directly to the age of the cows. This article is part of a Special Issue entitled 'Vitamin D Workshop'.