Pathophysiology of calcium and phosphorus disorders

MECHANISMS BY WHICH FEEDING SYNTHETIC ZEOLITE A AND DIETARY CATION ANION DIFFERENCE DIETS IMPACT MINERAL METABOLISM IN MULTIPAROUS HOLSTEIN COWS: PART I

The periparturient period is characterized by the increased demand for calcium (Ca) in dairy cows. This has resulted in the utilization of several different prepartal nutritional strategies to prevent hypocalcemia postpartum. The objective of our study was to determine the effects of feeding synthetic zeolite A (XZ), a negative dietary cation-anion difference (DCAD) diet, or a positive DCAD diet (CON) during the close-up period on peripartal mineral dynamics and hormones involved in calcium metabolism. To this end, one hundred and 21 multiparous Holstein cows, blocked by lactation number and expected due date were enrolled at 254 d of gestation and randomly assigned to 1 of 3 prepartum diets: CON (+190 mEq/kg; n = 40), -DCAD (-65 mEq/kg; n = 41), or a diet supplemented with sodium aluminum silicate (XZ; +278 mEq/kg, fed at 3.3% DM, targeting 500 g/day; n = 40; Protekta Inc.). Blood, urine, and saliva samples were collected from enrollment until parturition, with data analyzed and presented beginning 14 d before parturition (D-14) until parturition (D0), and on D1, D2, D3, D6, D9, D12, D15, D18, D21, D35, and D49 postpartum to assess mineral and hormone dynamics. Total fecal collections were performed in a subset of 8 cows per treatment group to assess fecal mineral loss. Data was analyzed as a randomized complete block design in SAS. Cows fed XZ and -DCAD had higher blood Ca concentrations compared with CON fed cows, with XZ fed cows exhibiting the highest blood Ca concentrations pre and postpartum. Cows fed XZ had decreased blood and salivary phosphorous (P), increased fecal water extractable phosphate (WEP), and the highest blood calcium concentrations pre and postpartum. Parathyroid hormone (PTH) was unaffected by diet but was increased at parturition in all treatments. Serotonin concentrations were increased in -DCAD and XZ fed cows compared with CON during the prepartum period. Our data indicate that XZ's improvement in blood Ca concentrations pre and postpartum most likely is regulated by a dietary P restriction. Taken together, these data suggest that XZ and -DCAD diets improve postpartum calcium metabolism, however, they appear to work through different mechanisms.

The Most Important Metabolic Diseases in Dairy Cattle during the Transition Period

This review paper provides an in-depth analysis of three critical metabolic diseases affecting dairy cattle such as subacute ruminal acidosis (SARA), ketosis, and hypocalcemia. SARA represents a disorder of ruminal fermentation that is characterized by extended periods of depressed ruminal pH below 5.5-5.6. In the long term, dairy herds experiencing SARA usually exhibit secondary signs of the disease, such as episodes of laminitis, weight loss and poor body condition despite adequate energy intake, and unexplained abscesses usually 3-6 months after an episode of SARA. Depressed milk-fat content is commonly used as a diagnostic tool for SARA. A normal milk-fat test in Holstein dairy cows is >4%, so a milk-fat test of <3% can indicate SARA. However, bulk tank testing of milk fat is inappropriate to diagnose SARA at the herd level, so when >4 cows out of 12 and <60 days in milk are suspected to have SARA it can be considered that the herd has a problem. The rapid or abrupt introduction of fresh cows to high-concentrate diets is the most common cause of SARA. Changes in ruminal bacterial populations when exposed to higher concentrate rations require at least about 3 weeks, and it is recommended that concentrate levels increase by no more than 400 g/day during this period to avoid SARA. Ketosis, a prevalent metabolic disorder in dairy cattle, is scrutinized with a focus on its etiological factors and the physiological changes leading to elevated ketone bodies. In total mix ration-fed herds, an increased risk of mastitis and reduced fertility are usually the first clinical signs of ketosis. All dairy cows in early lactation are at risk of ketosis, with most cases occurring in the first 2-4 weeks of lactation. Cows with a body condition score ≥3.75 on a 5-point scale at calving are at a greater risk of ketosis than those with lower body condition scores. The determination of serum or whole blood acetone, acetoacetate, beta-hydroxybutyrate (BHB) concentration, non-esterified fatty acids (NEFA), and liver biopsies is considered the best way to detect and monitor subclinical ketosis, while urine or milk cowside tests can also be used in on-farm monitoring programs. Concentrations >1.0 mmol/L or 1.4 mmol/L blood or serum BHB are considered diagnostic of subclinical ketosis. The standard threshold used for blood is 1.2 mmol/L, which corresponds to thresholds of 100 mcmol/L for milk and 15 mg/dL for urine. Oral administration of propylene glycol (250-400 g, every 24 h for 3-5 days) is the standard and most efficacious treatment, as well as additional therapy with bolus glucose treatment. Hypocalcemia is a disease of adult dairy cows in which acute hypocalcemia causes acute to peracute, afebrile, flaccid paralysis that occurs most commonly at or soon after parturition. Dairy cows are at considerable risk for hypocalcemia at the onset of lactation, when daily calcium excretion suddenly increases from about 10 g to 30 g per day. Cows with hypocalcemia have a more profound decrease in blood calcium concentration-typically below 5.5 mg/dL. The prevention of parturient paresis has been historically approached by feeding cows low-calcium diets during the dry period. Negative calcium balance triggers calcium mobilization before calving and better equips the cow to respond to the massive calcium needs at the onset of lactation. Calcium intake must be limited to <20 g per day for calcium restriction to be effective. The most practical and proven method for monitoring hypocalcemia is by feeding cows an acidogenic diet for ~3 weeks before calving. Throughout the review, emphasis is placed on the importance of early diagnosis and proactive management strategies to mitigate the impact of these metabolic diseases on dairy cattle health and productivity. The comprehensive nature of this paper aims to serve as a valuable resource for veterinarians, researchers, and dairy farmers seeking a deeper understanding of these prevalent metabolic disorders in dairy cattle.

Effects of timing of oral calcium administration on milk production in high-producing early-lactation Holstein cows

Supplementation of oral Ca via blanket administration of an oral Ca bolus at 0 and 24 h after calving has shown limited success in increasing production and minimizing adverse health events. Recent evidence that reductions in blood Ca at 4 d in milk (DIM) are more closely associated with negative outcomes than hypocalcemia at 0 to 24 h postpartum might explain this lack of Ca bolus efficacy. Therefore, our primary objective was to explore the effect of delayed oral Ca bolus supplementation on milk production, with secondary objectives of exploring the effects on disease incidence and postpartum blood Ca dynamics. We conducted a randomized controlled trial on multiparous Holstein cows (n = 998) from 4 herds in New York. At calving, cows were randomly assigned to 1 of 3 treatment groups: (1) control, no supplemental Ca at or around parturition (CON; n = 343); (2) conventional bolus, an oral Ca bolus containing 43 g of Ca at calving and 24 h later (BOL-C; n = 330); or (3) delayed bolus, an oral Ca bolus containing 43 g of Ca at 48 and 72 h after calving (BOL-D; n = 325). We created generalized linear mixed models to analyze differences in milk yield for the first 10 wk of lactation and serum total Ca (tCa) at 1 and 4 DIM between treatment groups; multivariable Poisson regression models were used to analyze adverse event outcomes (metritis, displaced abomasum, herd removal, or a combination of one or more of the 3) in the first 30 DIM. Milk yield increased by week and was not affected by treatment. However, a treatment by parity group interaction for milk yield showed that BOL-D cows in the third parity produced more milk than third-parity BOL-C or CON cows (BOL-D = 52.0 kg/d, 95% confidence interval [50.6, 53.4] kg/d, BOL-C = 47.9 [46.3, 49.5] kg/d, CON = 49.8 [48.2, 51.2] kg/d). The incidence of adverse health events was similar between treatments (BOL-D = 3.7%, BOL-C = 3.7%, CON = 3.6%). Serum tCa was lower at 1 than 4 DIM, and we detected no difference in tCa between treatment groups. Our findings suggest that delaying oral Ca bolus supplementation has limited influence on blood Ca concentrations but may be beneficial to cohorts of cows as a targeted prophylactic supplement to support milk production.

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.

Effects of Live Saccharomyces cerevisiae Yeast Administration in Periparturient Dairy Cows

Dairy cows face several challenges during the transition period, and the administration of live yeast might be useful to mitigate this stressful condition. In the current study, the effects of live yeast administration on milk production, feed intake, and metabolic and inflammatory conditions were evaluated. Multiparous Holstein cows were enrolled in this randomized controlled trial and received either a control diet (CTR, n = 14) or the control diet plus 4 g/d of live Saccharomyces cerevisiae yeast (LSC, n = 14) from -21 to 56 days relative to calving. Dry matter intake, milk yield and composition, and rumination time were monitored daily. Blood samples were collected at -21, -7, 3, 14, 28, 42, and 56 days relative to calving to evaluate the metabolic profile. Fecal samples were collected at 56 days relative to calving to measure volatile fatty acids and feed digestibility. No differences between groups were observed in dry matter intake. Compared with CTR, rumination time was lower in LSC in after calving. Although there were no differences in milk components between groups, LSC had greater milk yield in the last three weeks of the study than CTR. No differences were observed in inflammatory markers or other plasma metabolites, except for β-hydroxybutyrate, which was higher in LSC, and reactive oxygen metabolites (ROMs), which were lower in LSC. Overall, these outcomes suggest that live yeast supplementation had some positive effects on milk yield and oxidative status.

Circulating parathyroid hormone and serotonin in multiparous cows with differing postparturient serum calcium concentrations

Many multiparous dairy cows experience subclinical hypocalcemia (SCH) in the immediate postpartum period as they adapt to the demands of lactation. Furthermore, differing dynamics of SCH in the days following parturition are associated with varied health and production outcomes, with cows experiencing transient SCH producing more milk and facing fewer negative health events than cows with delayed or persistent SCH. Our objectives were to describe differences in mediators of calcium (Ca) homeostasis between cows experiencing differing Ca dynamics postpartum. A prospective cohort of 89 multiparous Holstein cows from 2 herds in New York were classified into 1 of 4 SCH groups based on mean serum total Ca (tCa) at 1 and 4 d in milk (DIM): normocalcemic (NC; [tCa] >1.89 mmol/L at 1 DIM and >2.25 mmol/L at 4 DIM, n = 30); transient SCH (tSCH; [tCa] ≤1.89 mmol/L at 1 DIM and >2.25 mmol/L at 4 DIM, n = 12); delayed SCH (dSCH; [tCa] >1.89 mmol/L at 1 DIM and ≤2.25 mmol/L at 4 DIM, n = 23); and persistent SCH (pSCH; [tCa] ≤1.89 mmol at 1 DIM and ≤2.25 mmol/L at 4 DIM, n = 24). Blood samples were collected at -5, -1, 1 through 5, 7, and 10 DIM and analyzed for tCa, parathyroid hormone (PTH), and serotonin. Repeated measures ANOVA models were used to analyze differences between SCH groups and changes over time for tCa, PTH, and serotonin. During the prepartum period, tCa was greater in the NC, tSCH, and dSCH cows as compared with the pSCH cows and there was marginal evidence for a difference in PTH between SCH groups. Postpartum tCa varied over time between SCH groups. Mean postpartum (95% confidence interval) tCa for respective SCH groups were NC = 2.32 (2.28, 2.35) mmol/L; tSCH = 2.20 (2.14, 2.25) mmol/L; dSCH = 2.17 (2.13, 2.21) mmol/L; and pSCH = 2.03 (1.99, 2.07) mmol/L. Mean concentrations of PTH in the postpartum period were NC = 70.1 (66.2, 74.4) pmol/L; tSCH = 72.1 (66.1, 79.2); dSCH = 75.8 (70.8, 81.5) pmol/L; and pSCH = 77.7 (72.4, 83.9) pmol/L. Serotonin was similar between SCH groups pre- and postpartum and followed a cyclical pattern from 1 to 10 DIM. Our results agreed with our hypothesis that differences in postpartum PTH might exist between cows experiencing different dynamics of SCH in the early lactation period; however, further studies are needed to confirm this difference. If true, this would suggest that Ca homeostasis may be disrupted in cows with dSCH and pSCH. Gaining a better understanding of these modulatory differences may aid in the prevention, management, and treatment of SCH.

Effects of isoenergetic supplementation as water use mitigation strategy on water footprint and health of nursing bull calves

Sustainable livestock systems focus on mitigating natural resource use such as water. Dietary management strategies can significantly reduce the water footprint of livestock animals; however, animal health is of concern when animals reduce water intake due to subacute dehydration. To evaluate potential consequences of this nutritional management intervention, a total of 23, 60 ± 3 days old nursing Holstein bull calves, weighing 94.7 ± 12.07 kg, were distributed in a completely randomized design and received one of three diets. Control was a basal diet composed of a non-medicated milk replacer (milk replacer; n = 7), and the additional two diets, were composed of the same non-medicated milk replacer in addition to either lipid [n = 8; milk replacer + menhaden fish oil (3 %)] or soluble carbohydrate [n = 8; milk replacer + corn starch (7%) isoenergetic to fat group] supplements. Animals were offered ad libitum mineral mix and water, as well as 120 g/day of a composite mix of dried microbrewery's spent grains. Data were analyzed as linear and generalized linear mixed models with diet as a fixed effect and animal as random utilizing R studio (R Core Team, 2021, Vienna, Austria; SAS Inst., Cary, NC). Within supplementation groups, lipid supplemented calves had the highest lymphocyte (63.24 vs 57.69 counts/100 lymphocytes; P < 0.033), and lowest neutrophil counts (29.3 vs 35.3 counts/100 lymphocytes; P < 0.047). Supplementation significantly increased total serum protein (P = 0.001) and skin moisture (P < 0.011), with carbohydrate group having the highest skin moisture (5.30 vs 3.99; P < 0.047). Supplementation also decreased fecal fluidity scores (P < 0.001) with no significant change in serum electrolytes (P > 0.256). No significant differences were found amongst treatments for the ingestive behavior (P > 0.338). The carbohydrate-supplemented calves significantly decreased all daily water footprints compared to the control and fat-supplemented groups: blue a 47.55 L decrease, (P < 0.001), green a 265.62 L decrease (P = 0.005), and gray a 55.87 L decrease (P = 0.009) water footprint, as well as total water footprint (369.04 L, P = 0.004). Our results indicate the potential to maintain animal performance while increasing water use efficiency through diet supplementation tailored to mitigate water use, without adverse effects on animal health.

The Use of Additives to Prevent Urolithiasis in Lambs Fed Diets with a High Proportion of Concentrate

This study aimed to evaluate the effectiveness of different additives in preventing urolithiasis in lambs fed a diet rich in concentrate and their impact on performance and blood and urinary parameters. Thirty-two noncastrated male lambs, crossbred Dorper × Santa Inês, with initial body weights (BWs) of 23 ± 0.1 kg and ages of 50 ± 5 days, were kept in individual pens and fed a diet composed of 6% Cynodon ssp. hay and 94% concentrate and subjected to four treatments: CON without inclusion of additives, addition of ACL 5 g/kg of dry matter (DM), addition of CCL 6.3 g/kg of DM, and addition of BZA 5 g/kg of DM. There was no effect of treatment or interaction with time on blood parameters (p > 0.050), and performance characteristics, morphometry of ruminal papillae, and scores of cecum and rumen lesions were not affected by the addition of additives to the diet (p > 0.050). Greater urinary acidification was observed in animals from CCL and ACL treatments (p = 0.033). Calcium chloride acidified the urinary pH and can be used instead of ammonium chloride at a concentration of 0.63% based on DM, when this is the objective.

Graduate Student Literature Review: Mitochondrial response to heat stress and its implications on dairy cattle bioenergetics, metabolism, and production

The dairy industry depends upon the cow's successful lactation for economic profitability. Heat stress compromises the economic sustainability of the dairy industry by reducing milk production and increasing the risk of metabolic and pathogenic disease. Heat stress alters metabolic adaptations, such as nutrient mobilization and partitioning, that support the energetic demands of lactation. Metabolically inflexible cows are unable to enlist the necessary homeorhetic shifts that provide the needed nutrients and energy for milk synthesis, thereby impairing lactation performance. Mitochondria provide the energetic foundation that enable a myriad of metabolically demanding processes, such as lactation. Changes in an animal's energy requirements are met at the cellular level through alterations in mitochondrial density and bioenergetic capacity. Mitochondria also act as central stress modulators and coordinate tissues' energetic responses to stress by integrating endocrine signals, through mito-nuclear communication, into the cellular stress response. In vitro heat insults affect mitochondria through a compromise in mitochondrial integrity, which is linked to a decrease in mitochondrial function. However, limited evidence exists linking the in vivo metabolic effects of heat stress with parameters of mitochondrial behavior and function in lactating animals. This review summarizes the literature describing the cellular and subcellular effects of heat stress, with a focus on the effect of heat stress on mitochondrial bioenergetics and cellular dysfunction in livestock. Implications for lactation performance and metabolic health are also discussed.

Considerations in the Diagnosis and Treatment of Early Lactation Calcium Disturbances

This article reviews the history of clinical hypocalcemia and the evolving definition of subclinical hypocalcemia, targeting a concept for consideration that not all hypocalcemia is negative. With a goal of presenting bovine practitioners information to assist with individual animal hypocalcemia diagnosis and treatment as well as herd-level monitoring and prevention, we present current methods of direct calcium measurement, therapeutic interventions for clinical hypocalcemia, and postpartum calcium supplementation options and their efficacy. We encourage veterinarians to understand calcium dynamics in the immediate postpartum period and evaluate how individual cow therapy and herd prevention protocols can assist with supporting calcium regulation.

Effect of Sugar Beet Pulp and Anionic Salts on Metabolic Status and Mineral Homeostasis during the Peri-Parturient Period of Dairy Sheep

Sugar beet pulp is a popular by-product of sugar extraction; however, it can potentially cause depletion of Ca availability due to its oxalic content. The experiment examined the effect of sugar beet pulp and anionic salts administration during the dry period on the serum concentration of calcium, magnesium, phosphate, and potassium of dairy sheep. Eighty-seven sheep were divided into three groups (A, B, and C) according to their body condition score (BCS) and age at 40 days before the expected lambing. All groups received alfalfa hay, mixed grass straw, and a concentrate supplement. The concentrate fed to groups B and C contained sugar beet pulp. The nutritional value fed to all three groups was similar, except for Dietary Cation Anion Difference (DCAD). Animals of group A had a DCAD of +198 mEq/kg, animals of group B of +188 mEq/kg, and animals of group C were fed 20 gr/d ammonium chloride to achieve a negative DCAD (-52 mEq/kg). All groups were fed the same ration after lambing. Blood samples were collected 30 d, 20 d, 17 d, 14 d, 10 d, 7 d, and 4 d before lambing (a.p.), 6 h, 12 h, 24 h, 7 d, 10 d, and 15 d after lambing (p.p) for calcium, magnesium, phosphate, and potassium, and 30 d a.p., 7 d, and 15 d p.p. for beta hydroxybutyrate acid (BHBA) concentrations. Urine samples were also collected 20 d, 10 d, 4 d a.p., and 7 d p.p for the evaluation of pH levels. Ca levels of the control group decreased earlier and were lower at 4 d a.p. compared to those of group B and C. Additionally, the control group showed lower p values compared to group C at 20 d and 17 d a.p. P levels recovered earlier post parturition in young (age 1-1.5 years old) compared to older ewes. Group C had lower urine pH values throughout the pre-parturient period, reflecting the acidifying effect of the administered ammonium chloride, without any side effect on macromineral blood concentration. Feeding sugar beet pulp and systemic acidifying before parturition is considered safe and might even be beneficial in preventing hypocalcemia.

Modifying the diets of captive proboscis monkeys in a temperate zoo to reduce weight loss and renal disease

In animal husbandry, diets should help in maintaining a healthy body condition, support reproduction, and promote species-specific longevity. It is recommended to feed folivorous primates kept in zoos a high-fiber diet, i.e., leaves, although satisfying such a requirement is challenging in temperate regions because it is difficult to obtain fresh leaves, especially in autumn and winter. As equally important for their appropriate treatment, it is valuable to provide details of clinical reports of medical problems and pathological findings, although such clinical reports are rather limited. Therefore, in foregut-fermenting proboscis monkeys (Nasalis larvatus), we (1) described the individual clinical reports of renal disease and weight loss at the Yokohama Zoological Gardens in Japan, (2) determined the nutritional profile of the diets supplied to these animals because other potential triggers for their renal disease and weight loss could be excluded, (3) modified the diet regimen to minimize weight loss and the development of hypercalcemia and hypophosphatemia, and (4) assessed the effects of such dietary modification by comparing the body weight and the Ca and P concentrations and the Ca/P ratios in the blood before and after diet modification with a comparison of these measurements between zoo and free-ranging individuals. Based on the nutritional profile of the diets, we concluded that the reported cases of renal failure might be caused by consumption of leaves with a Ca/P ratio far above the appropriate level in autumn and winter. Additionally, the dietary modification of minerals and metabolizable energy achieved certain beneficial effects on zoo-kept proboscis monkeys.

Summer Season-Related Heat Stress Affects the Mineral Composition of Holstein Dams' Colostrum, and Neonatal Calves' Mineral Status and Hematological Profile

This study examines the effect of season-related heat stress in dams on mineral status, and hematological profile of their calves. Ten Holstein dams (LowT group) were exposed to the 49-day-long period of low air temperature (5.2 ± 0.5 °C) and ten dams (HighT group) were exposed to a 53-day-long high air temperature (27.4 ± 0.4 °C). The dams' blood samples were taken one hour after parturition, while colostrum was sampled at 2, 14, and 26 h after calving. Ca, P, Mg, Na, K, Fe, Zn, Mn, and Se concentrations were significantly lower while Cu and Co concentrations were significantly higher at least in two examined colostrum sampling points in HighT group. Calf`s blood samples were taken before 1^st colostrum intake, and on days 1, 2, 3, and 7 postnatal. Ca, P, Na, K, Fe, Cu, Zn, Mn, Se, and Co were significantly lower while concentration of Mg was significantly higher in calves that originated from HighT group at least at two examined sampling points. Season affected dam's blood mineral status but the pattern was not always the same as in calves, since Na, K, Cu, and Co were significantly higher in HighT group. Calves that originated from HighT group had significantly lower hemoglobin, hematocrit, MCV, MCH, and MPV values, as well as neutrophils and monocyte counts, while platelets, eosinophils, basophils, and lymphocyte counts were significantly higher. Season-related heat stress leads to a reduction of the most minerals in both dams' colostrum and calves' blood and certain minerals' deficiencies are linked to impaired calves' hematological adaptation.

Effect of dry period length on plasma minerals and oxidative stress around parturition and milk yield in high-producing Holstein dairy cows

The aim of present study was to evaluate the effect of dry period length (56 vs. 28 days) on plasma minerals, albumin, total protein and globulin, oxidative status, and milk production in high-producing dairy cows (13,500 ± 1800 kg milk in previous 305-day lactation). A total of 120 multiparous Holstein cows were used in a repeated measurement mixed model (animal was considered random effect) with two experimental groups and 60 replicates each: 1-long dry period (LDP, 56-day dry period) and 2-short dry period (SDP, 28-day dry period). While LDP cows received two different rations in far-off and close-up periods (DCAD = 189 and - 130 Meq/Kg, respectively), the SDP cows received only the close-up ration (- 130 Meq/Kg) without passing the far-off stage. Blood samples for minerals, oxidative stress, and metabolites (albumin, total protein) were collected on calving day, 24 and 48 h after parturition. Milk samples of all cows in each group were collected monthly (four months from parturition to 120 DIM) and analyzed for milk fat, protein, and somatic cell count (SCC). Results showed that SDP had no effect on plasma calcium (Ca), ionized calcium (iCa), magnesium (Mg), and phosphorus (iP). Total antioxidant capacity (TAC) in the SDP cows was higher (P < 0.05) than the LDP cows. The treatment had no significant effect on plasma concentration of total protein, albumin, globulin, and superoxide dismutase (SOD) activity. A positive significant (P < 0.05) correlation was observed between plasma Mg and TAC in SDP group. Short dry period reduced (P < 0.05) milk production (48.39 vs. 51.95 kg/day; about 7%) during the first 120 days in milk. However, SDP cows had higher (P < 0.05) milk protein content compared to LDP group. The log-transformed of somatic cell count (LnSCC) was not affected by the treatment. It was concluded that a short dry period (28 days) had no negative effect on plasma Ca, iCa, Mg, and iP and even could improve TAC in high-producing Holstein cows.

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.

Supplementing a Clay Mineral-Based Feed Additive Modulated Fecal Microbiota Composition, Liver Health, and Lipid Serum Metabolome in Dairy Cows Fed Starch-Rich Diets

Starch-rich diets are a commonly adopted strategy in order to sustain high milk yields in dairy cows. However, these diets are known to increase the risk of gut dysbiosis and related systemic health disorders. This study aimed to evaluate the effects of supplementing a clay mineral-based feed additive (CM; Mycofix® Plus, BIOMIN) on fecal microbiota structure, fecal short-chain fatty acid (SCFA) fermentation, serum metabolome, and liver health in primiparous (PP, n = 8) and multiparous (MP, n = 16) early-lactation Simmental cows (737 ± 90 kg of live body weight). Cows were randomly assigned to either a control or CM group (55 g per cow and day) and transitioned from a diet moderate in starch (26.3 ± 1.0%) to a high starch diet (32.0 ± 0.8%). Supplementation of CM reversed the decrease in bacterial diversity, richness, and evenness (p < 0.05) during high-starch diet, demonstrating that CM supplementation efficiently eased hindgut dysbiosis. The CM treatment reduced levels of Lactobacillus in PP cows during starch-rich feeding and elevated fecal pH, indicating a healthier hindgut milieu compared with that in control. Butyrate and propionate levels were modulated by CM supplementation, with butyrate being lower in CM-treated MP cows, whereas propionate was lower in MP but higher in PP cows. Supplementing CM during high-starch feeding increased the concentrations of the main primary bile salts and secondary bile acids in the serum and improved liver function in cows as indicated by reduced levels of glutamate dehydrogenase and γ-glutamyl-transferase, as well as higher serum albumin and triglyceride concentrations. These changes and those related to lipid serum metabolome were more pronounced in PP cows as also corroborated by relevance network analysis.

Effects of Postpartum Supplemental Oral Ca for Dairy Cows Fed Prepartum Dietary Acidogenic Salts

Simple Summary

Low blood calcium after calving is problematic in dairy cows, particularly for older cows and for Jerseys vs. Holsteins. Feeding acidogenic salts before calving and oral Ca supplementation post-calving help mitigate this. We evaluated: (1) a novel approach to delivering acidogenic salts prepartum applicable to small dairies and (2) the combined effects of prepartum acidogenic salts and postpartum oral Ca supplementation for both Holsteins and Jerseys of varying parity. We found this novel approach to providing acidogenic salts to be effective. We also found preliminary evidence that shortening the time of application of this technology may enhance its beneficial effects. Responses to prepartum acidogenic salts and postpartum oral calcium supplementation were very different for second vs. greater than second parity cows. Finally, we found an increased risk of low blood calcium, particularly in older Jersey cows, when either prepartum urinary calcium excretion was low or colostrum production was high.

Abstract

Postpartum hypocalcemia is a problem in dairy cows. Both the Jersey vs. Holstein breed and increasing parity are known risk factors. Our objectives were: (1) to evaluate a simple approach to provide dietary acidogenic salts suitable for application on small dairies and (2) to evaluate the combined effects of degree of acidification and oral Ca supplementation along with breed and parity group on periparturient Ca status of Holstein and Jersey cows. Cows were moved weekly from the far-off dry pen at 260 days pregnant to the close-up pen, where all cows received the acidogenic diets. The diet was offered as a total mixed ration and CaCl₂, and our source of acidogenic salts was top-dressed in liquid form and mixed in by hand. Thirty-six cows were blocked by parity group (parity = 2 vs. parity ≥ 3) and breed (Holstein vs. Jersey) and assigned to one of two treatments (no intervention or postpartum oral Ca bolus supplementation) in an alternating fashion, based on expected date of parturition. Urinary acidification appeared complete within 3–4 days. Increased urinary Ca excretion was >93% of maximum from 7–21 days before falling to <5% of maximum by 28 days. Serum Ca concentrations 12–24 h postpartum were lower for Jerseys vs. Holsteins and for parity ≥ 3 vs. parity = 2 cows. Serum Ca over 6–48 h postpartum decreased and increased, respectively, with oral Ca supplementation for parity = 2 and parity ≥ 3 cows. Decreased prepartum urinary Ca excretion and increased colostrum yield appear to be independent risk factors of hypocalcemia for parity ≥ 3 Jerseys.

Physiological adaptations in early-lactation cows result in differential responses to calcium perturbation relative to nonlactating, nonpregnant cows

The peripartal cow experiences a rapid change in calcium metabolism at the onset of lactation. Research has focused on understanding how mammary-derived factors, such as serotonin (5HT) and parathyroid hormone like hormone (PTHLH), aid in coordinating these calcemic adaptations to lactation. Therefore, the aim of our study was to determine how induced subclinical hypocalcemia influences physiological responses, specifically the 5HT-PTHLH-Ca axis, in lactating and nonlactating dairy cows to elucidate the potential contribution of the mammary gland. Twelve nonlactating, nonpregnant (NL) multiparous Holstein cows and 12 early-lactation (EL) multiparous Holstein cows received either (1) a continuous 24-h intravenous solution of 0.9% NaCl or (2) 5% ethylene glycol tetraacetic acid (EGTA) solution in 0.9% NaCl (n = 6 EL, n = 6 NL per treatment) with the aim of maintaining blood ionized calcium (iCa) less than 1.0 mM. Mammary gland biopsies were taken immediately after and 48 h after termination of infusion. Blood was sampled hourly during infusion and 4, 8, 12, 24, 48, and 72 h after termination of infusion. Infusion of EGTA successfully decreased blood iCa concentrations. However, EL EGTA-infused cows required increased rates of EGTA infusion to maintain iCa below 1.0 mM. Circulating and mammary serotonin concentrations were increased in EL relative to NL cows, with no difference as a result of EGTA infusion. Mammary PTHLH expression was increased in EL cows, with highest expression observed in EL EGTA-infused cows. Collectively, these data demonstrate the robust adaptations EL cows have to maintain Ca homeostasis and the supporting roles 5HT and PTHLH may play.

Peri-parturient hypocalcemia in goats: Clinical, hematobiochemical profiles and ultrasonographic measurements of postpartum uterine involution

Background and Aim:

Hypocalcemia in goats occurs around the time of parturition and is caused by decreasing level of calcium less than 10 mg/dL. This investigation characterized the hematological and biochemical profiles of peri-parturient hypocalcemia in goats and study the effects of hypocalcemia on uterine involution during the postpartum period on day 0 and then weekly postpartum (day +7, +14, +21, +28, +35, till +42).

Materials and Methods:

Forty-five polyparous native breed does age 3-5 years and weighing 40–60 kg were assigned to control and hypocalcemia groups based on their health history, clinical and biochemical findings. The control group included 10 clinically healthy pregnant does, and the hypocalcemia group included 35 late pregnant does that suffered from anorexia, weakness, muscle tremors of the hind limbs, and an inability to stand. Clinical examination and blood sampling in both groups were performed approximately 14 days before the expected time of kidding (day −14), at kidding day (day 0), on day +21, and +42 postpartum. Sonographic measurements were used to monitor uterine involution on day 0 and then weekly once the animal was postpartum (day +7, +14, +21, +28, +35, till +42) in both groups.

Results:

Results of sonographic measurement revealed that the hypocalcemia group had a greater (p<0.05) size of the uterus as assessed transrectally and retarded uterine involution when compared with the control group. Laboratory findings revealed that does in both groups showed lower red blood cells, packed cell volume%, and hemoglobin (Hb) concentrations on day −14 before kidding and day 0 when compared with postpartum measurements. A significant increase (p<0.05) in total leukocyte counts, neutrophil, serum glucose, and cortisol levels with a significant decrease (p<0.05) in lymphocytes. Significant decreases (p<,0.05) in serum calcium, phosphorous, vitamin D, and total antioxidant capacity levels with significant (p<,0.05) increases in serum malondialdehyde were recorded on day 0 and day −14 in the hypocalcemia group when compared with the control group.

Conclusion:

This investigation provides evidence that hypocalcemia in does causes both metabolic and oxidative stress during peri-parturient periods while also retarding uterine involution during postpartum periods.

Association of subclinical hypocalcemia dynamics with dry matter intake, milk yield, and blood minerals during the periparturient period

Subclinical hypocalcemia (SCH) affects many high-producing dairy cows in the postpartum period. Recent work has shown that cows experiencing prolonged or delayed SCH are at increased risk for disease and produce less milk than cows experiencing a transient reduction in or normal concentrations of plasma Ca following parturition. Our objective was to determine the association between different postpartum SCH dynamics with pre- and postpartum dry matter intake (DMI), milk yield, and blood mineral concentrations. Data were retrospectively collected from multiparous Holstein cows (n = 78), and cows were classified into 1 of 4 SCH groups based on mean blood total Ca (tCa) concentrations at 1 and 4 d in milk (DIM): normocalcemic (NC; [tCa] >1.95 mmol/L at 1 DIM and >2.2 mmol/L at 4 DIM, n = 28); transient SCH (tSCH; [tCa] ≤1.95 mmol/L at 1 DIM and >2.2 mmol/L at 4 DIM, n = 27); delayed SCH (dSCH; [tCa] >1.95 mmol/L at 1 DIM and ≤2.2 mmol/L at 4 DIM, n = 6); and persistent SCH (pSCH; [tCa] ≤1.95 mmol at 1 DIM and ≤2.2 mmol/L at 4 DIM, n = 17). Linear mixed models were created to analyze the change in pre- and postpartum DMI, milk yield, and blood mineral concentrations over time as well as differences between SCH groups. Prepartum intake was similar between groups, but the NC and tSCH cows consumed more feed than the pSCH or dSCH cows during the first 3 wk of lactation. The tSCH cows produced more milk than the other 3 groups during the first 6 wk of lactation. Postpartum blood tCa and Mg were different between SCH groups and were highest in the NC cows and lowest in the pSCH cows. Our results suggest that the high level of DMI consumed by the NC and tSCH cows in the postpartum period supported an appropriate homeostatic response to the increased Ca demands of lactation, allowing for higher milk yield compared with their counterparts experiencing delayed or prolonged episodes of SCH.

Metabolic and behavior changings during the transition period as predictors of calving proximity and welfare of dairy goats

This Research aimed to evaluate the metabolic status and behavior changes during the transition period in dairy goats from three breeds, under tropical conditions. Thirty multiparous female goats were kept in pens, distributed randomly by breeds. Infrared cameras were fitted in the pens to monitor the animals, and its activities were recorded. Goats displayed varied idle, standing, walking, and feeding behaviors at kidding day (P < 0.10) when compared with the days after and before. Agnostic interactions prevailed between 3.33 and 7.98% of the time on the day of kidding. There was a day effect for the exploratory activities (P < 0.10), where the most exploratory activities were observed on the day of kidding. The milk production and fat content differed according to breed and lactation week. Collective pens for lactating goats, kept in a tropical environment, do not compromise the social behavior and welfare.

Subclinical hypocalcaemia follows specific time-related and severity patterns in post-partum Holstein cows

Hypocalcaemia is a common metabolic disorder of post-parturient dairy cows; enhancement of our knowledge regarding Ca dynamics would improve cow health and welfare. This study investigated the presence of time- and severity-related subclinical hypocalcaemia (SCHCa) patterns in Holstein cows after calving and their association with diseases during the first week of lactation. A total of 938 cows from nine herds were blood sampled on days 1, 2, 4 and 8 post-partum, and serum Ca concentration was measured with atomic absorption. Subclinical ketosis (serum β-hydroxybutyrate≥1.2 mmol/L) and cases of retained foetal membranes, metritis (MET), mastitis, ketosis and displaced abomasum (DA) were recorded. Using receiver operating characteristic (ROC) analysis, the SCHCa cut-off was identified at serum Ca ≤ 2.09 mmol/L. Hierarchical and two-step cluster analysis classified cows to seven clusters based on test day cow Ca records and overall SCHCa status. Two clusters (NORM and HIGH) included 318 normocalcaemic cows and five clusters (SCH-1 to -5) those that were at least once subclinically hypocalcaemic (n = 620). A second ROC analysis was performed in order to distinguish mild from severe cases of SCHCa in these 620 cows; this cut-off was identified at 1.93 mmol/L. The associated risk of disease with Ca clustership was assessed with generalized linear mixed models. Overall incidence of SCHCa was 66.1%. Clusters SCH-1 and SCH-2 included cows with short-term SCHCa of day 1 and day 2, respectively, while SCH-3 included cows with severe and prolonged SCHCa extending to day 4 and beyond. Clusters SCH-4 and SCH-5 included cows with delayed SCHCa, which culminated on days 4 and 8, respectively. Compared to NORM cows in HIGH had lower risk of MET and no cases of DA. Cows in SCH-3 had higher risk of being diagnosed with retained foetal membranes, DA or any disease during the study period. Cows in SCH-5 had higher risk of being diagnosed with ketosis, subclinical ketosis or any disease. In conclusion, there are multiple normocalcaemic and hypocalcaemic patterns that are differently associated with disease risk.

Parathyroid hormone response in treatment of subclinical hypocalcemia in postpartum dairy cows

The aim of this study was to evaluate different treatments of postpartum subclinical hypocalcemia in dairy cows with emphasis on PTH response. Twenty four cows with subclinical hypocalcemia (Ca 1.4-2.0 mmol/L), out of 180 Holstein cows tested, were assigned in one of three equal groups: (1) CON received no Ca supplementation, (2) PO-Ca received 1000 mL of oral Ca suspension, immediately after establishing hypocalcemia, and 500 mL of the suspension 12 h after, (3) IV-Ca intravenously received 500 mL of Ca immediately after establishing hypocalcemia. The blood samples were taken up to 48 h after initial treatment for determination of Ca, iP, Mg and PTH concentrations. Urine pH was also evaluated up to 48 h after initial treatment. Compered to CON cows that were hypocalcemic up to the 48 h, Ca concentrations were significantly higher in PO-Ca up to hour 8 and IV-Ca up to hour 24. At first 2 h, PTH concentrations were significantly lower, compared to CON, only in IV-Ca, while at hour 4 PTH concentrations were significantly lower in both treated groups. At hours 24 and 48, PTH concentrations were significantly lower only in PO-Ca compared to CON group. Urine pH values in CON indicate alkalosis and were significantly lower both in PO-Ca and IV-Ca group, up to 12 h and 24 h respectively. In conclusion, both treatments mitigated hypocalcemia in cows, but with significantly different PTH response. Due to adequate PTH response, normocalcemia is established in CON and expected transient hypocalcemia is avoided in IV-Ca cows.

Hormonal and metabolic profiles related to placental retention with emphasis on oxidative stress and serotonin receptors in pluriparous buffaloes

This study was designed to investigate the hormonal and metabolic factors associated with placental retention in buffaloes with respect to the roles of oxidative stress biomarkers and serotonin receptors. Blood samples were collected at weeks 3, 2 and 1 pre-partum and at calving from 37 buffaloes; thirty normally dropped their placentae (Non-RFM group) and 7 dropped their placentae after 12 hr post-calving (RFM group). Serum progesterone (P₄ ), oestradiol, cortisol, non-esterified fatty acids (NEFA), beta-hydroxybutyric acid (BHBA), antioxidant/oxidant biomarkers and mineral concentrations were assessed. Histopathology and histochemistry were implemented to detect collagen in foetal placental tissues. Immunohistochemistry for serotonin receptors in placental tissues was performed. Significant elevations in P₄ , cortisol, NEFA, BHBA and oxidative biomarkers concentrations were observed in the RFM group. However, oestradiol, antioxidants and mineral concentrations were significantly lower in RFM buffaloes than Non-RFM group. Histopathological examination revealed degenerative changes and necrosis in retained placental tissue compared with that in normal placental tissues. Serotonin receptors were significantly expressed with collagen condensation in retained placental tissues. Furthermore, inferior reproductive performance was pronounced in the retained group. In conclusion, retained foetal membranes in buffaloes were associated with hormonal imbalance, metabolic perturbation, oxidative stress, serotonin receptor upregulation and markedly reduced fertility indices.

Effect of subclinical and clinical hypocalcemia and dietary cation-anion difference on rumination activity in periparturient dairy cows

Rumination involves a complex series of muscle contractions that bring a bolus of ingesta to the mouth for further mastication before it is swallowed again. Healthy cows ruminate 8 to 9 h/d. Hypocalcemia is known to disrupt nerve and muscle function. Our hypothesis was that hypocalcemia in periparturient cows would reduce rumination activity. Twenty-six Holstein cows entering their third lactation or greater were fed a control diet [dietary cation-anion difference (DCAD) = +196 mEq/kg of dry matter (DM)] or a low DCAD diet supplemented with anions (DCAD = -9 mEq/kg of DM) prepartum. Periparturient plasma Ca concentration and rumination rate were determined. Four of 12 control cows developed clinical milk fever, necessitating intravenous Ca therapy. Rumination rate decreased in all cows around the time of calving. Rumination rate on the first and second day of lactation was highly correlated with the cow's plasma Ca concentration on the first day of lactation. In one of our statistical models, a normocalcemic cow was defined as a cow whose plasma Ca concentration remained above 2.00 mM. Cows were retrospectively classified as normocalcemic, subclinically hypocalcemic, or clinically hypocalcemic (milk fever). Only 4 cows were considered normocalcemic, and all had been fed the low DCAD diet. Normocalcemic cows spent more time ruminating on the first day after calving than subclinically hypocalcemic cows or cows with milk fever. Cows with milk fever had a lower rumination rate than normocalcemic cows through d 3 of lactation. Rumination activity in cows with milk fever was almost nondetectable in the hours before and after intravenous Ca treatment for an extended period, despite the return of muscle function that allowed the cows to stand and eructate following treatment. Other statistical models using different definitions of normocalcemia gave qualitatively similar results. Diet had a great effect on plasma Ca concentration and rumination rate. Even when cows with clinical milk fever were removed from the control cow data set, cows on the low DCAD diet had significantly greater plasma Ca concentrations in the first 36 h after calving and a higher rumination rate on d 1 of lactation (248 ± 26 min) than control cows (158 ± 32 min).

Relationship between expression pattern of vitamin D receptor, 1 alpha-hydroxylase enzyme, and chemokine RANTES genes and selected serum parameters during transition period in Holstein dairy cows

Objectives

The objective of the present study was to evaluate the pattern of genetic expression of vitamin D receptor (VDR), 1 alpha-hydroxylase (1α-OHase) enzyme and chemokine regulated on activation normal T-cell expressed and secreted (RANTES) in peripheral blood of Holstein dairy cows during transition period.

Methods

Blood samples were collected from 16 Holstein dairy cows at 3 weeks prior expected date of delivery (EDD), at the day of parturition, and 3 weeks post-partum for assessment of expression profile of studied genes using real-time PCR and measurement of glucose, ionized calcium (Ca), parathyroid hormone (PTH), inorganic phosphorous (P), sodium (Na), potassium (K), chloride (Cl), and magnesium (Mg) levels.

Results

Compared with 3 weeks prior EDD, VDR gene expression decreased significantly at the day of parturition then increased significantly at 3 weeks post-partum. The genetic expression of 1α-OHase enzyme as well as PTH, K, Na and Cl levels increased significantly at the day of parturition. The Ca level decreased significantly at the day of parturition then increased significantly at 3 weeks post-partum. The P level increased significantly at the day of parturition then decreased significantly at 3 weeks post-partum. Glucose level decreased significantly at the day of parturition and at 3 weeks post-partum. RANTES gene expression showed non-significant changes among the three different time points. The expression of VDR gene had a negative correlation with the expression of 1α-OHase enzyme gene, and serum levels of glucose, PTH, P and K, but had a positive correlation with the serum Ca level. The expression of 1α-OHase enzyme gene had a positive correlation with serum levels of PTH, P and K, but had a negative correlation with the serum Ca level.

Conclusions

Results of the current study indicate the importance of monitoring the genetic expression of VDR and 1α-OHase enzyme as indicators of metabolic changes during transition period, suggesting that they are candidate genes to judge the health status of dairy cows during such period.

Influence of a mineral supplement containing calcium, phosphorus and micronutrients on intake, digestibility, performance and mineral status of young Nellore bulls in a feedlot

We measured nutrient intake and digestibility, performance and mineral status of young Nellore bulls fed three diets with and without supplementation comprising calcium (Ca), phosphorus (P) and micro-minerals during the growing and finishing phases. Five bulls were slaughtered at the beginning of the experiment to measure initial mineral status. Forty-two young Nellore bulls (initial bodyweight (mean ± s.d.) 270.4 ± 36.6 kg, age 8 months) were assigned for 125 days to one of six treatments: sugarcane as a roughage source plus a concentrate based on soybean meal and soybean hull with (SH100) and without (SH0) supplementation; sugarcane as a roughage source plus a concentrate based on soybean meal and ground maize with (SC100) and without (SC0) supplementation; and maize silage as a roughage source plus a concentrate based on soybean meal and maize with (CS100) and without (CS0) supplementation. The experiment was conducted as a completely randomised design with a 3 × 2 factorial arrangement of treatments. Nutrient intake and digestibility, bone and serum parameters related to Ca and P metabolism, and liver mineral concentrations were measured. Nutrient intake, digestibility and performance were not affected (P &gt; 0.10) by the mineral factor. Water intake was higher (P &lt; 0.05) with SH100 than with all other diets. Rib-bone breaking strength and density according to dual-energy X-ray absorptiometry were reduced (P &lt; 0.04) in the absence of supplementation. Metatarsus parameters were not affected (P &gt; 0.10). Liver copper (Cu) content was reduced (P &lt; 0.01) in diets without supplementation. In conclusion, the short-term absence of mineral supplementation did not influence intake and digestibility. However, depending on diet type, absence of Cu may reduce the hepatic Cu content, and a low Ca:P ratio may stimulate bone reabsorption without compromising performance. Therefore, under our conditions, mineral requirements are overestimated by nutritional systems.

Do calcium and magnesium deficiencies in reproducing ewes contribute to high lamb mortality?

High lamb mortality continues to be a significant economic and welfare problem within the Australian sheep industry, with 20–30% of lambs born in commercial flocks dying mostly within 3 days of birth. Clinical hypocalcaemia and hypomagnesaemia cause ewe mortality, and, subsequently, either fetal or lamb death, but it is not known whether subclinical deficiencies of calcium (Ca) and magnesium (Mg) compromise lamb survival. This review considers the potential mechanisms through which Ca and Mg deficiencies may influence lamb survival, and factors influencing the risk of deficiency. Pastures grazed by lambing ewes may be marginal in calcium (Ca; &lt;4 g/kg DM) and magnesium (Mg; &lt;0.9 g/kg DM) but also have a high dietary cation–anion difference (&gt;12 meq/100 g DM) and high concentrations of potassium (K; &gt;30 g/kg DM) and nitrogen. In young cereal crops, sodium concentrations are also often low (&lt;0.9 g/kg DM). This combination of minerals and other nutrients creates an imbalance in supply and increases susceptibility to acute Ca (hypocalcaemia) and Mg (hypomagnesaemia) deficiency. Calcium is required for smooth muscle function and has a direct role in uterine contraction, so may influence the duration of parturition. Low Ca and Mg intake both influence insulin release and sensitivity, low Mg results in poor glycaemic control and insulin resistance by impairing both insulin secretion and its action on peripheral tissues, also potentially altering the duration of parturition as well as risk of metabolic disease. Magnesium is also a neuroprotectant that slows the neuronal damage during hypoxia and has been linked with thermogenesis in offspring and increased immunoglobulins in colostrum. These functions indicate potential importance in improving the ease of parturition and improved ability of the newborn lamb to thermoregulate and survive after birth. Subclinical Ca and Mg deficiencies commonly occur in 20% of lambing ewes grazing temperate pastures, so further studies are warranted to investigate whether correction of these deficiencies can improve lamb survival.

Effect of dietary difructose anhydride III supplementation on bone mineral density and calcium metabolism in late-lactation dairy cows

The aim of the present study was to examine the effect of 28 days of dietary difructose anhydride (DFA) III supplementation on calcium (Ca) metabolism in late-lactation dairy cows. Twenty-four multiparous pregnant Holstein cows were divided into two groups. The DFA group was fed total mixed ration (TMR) supplemented with 40 g of DFA III, and the control group was fed TMR only. The replenishment of bone Ca reserves was evaluated by measuring bone mineral density (BMD) and blood biochemical bone markers. Serum Ca concentrations, urinary Ca-to-creatinine (Cre) (Ca/Cre) ratios, and milk Ca concentrations were also analyzed. The BMD of the 4th caudal vertebra in the DFA group was higher than in the control group on day 28. With respect to bone markers, the ratios of undercarboxylated osteocalcin (ucOC) to osteocalcin (OC) in the DFA group were significantly lower than those in the control group on days 21 and 28. Milk Ca concentrations in the DFA group were also higher than those in the control group on days 14, 21, and 28, whereas serum Ca concentrations and urinary Ca/Cre ratios were unchanged in both groups. These results suggest that dietary supplementation with DFA III increased BMD and decreased serum ucOC/OC ratios in late-lactation dairy cows; this indicates that the replenishment of bone Ca reserves may be enhanced by dietary DFA III supplementation.

High metabolic activity of tissue-nonspecific alkaline phosphatase not only in young but also in adult bone as demonstrated using a new histochemical detection protocol

Tissue-nonspecific alkaline phosphatase (TNAP) is playing a key role in bone calcification, as has been demonstrated in different mammalian species including human and rodents. However, to investigate age-related changes during life history, histochemical demonstration of TNAP is severely hampered, particularly in the elderly, by technical difficulties associated with sectioning calcified tissue. Sufficient fixation must precede decalcification since poorly fixed bone tissue is exposed to the deleterious effects of decalcification reagents. In order to find a method that would allow cryosectioning of bone without loss of TNAP activity, we assessed the efficacy of different fixation reagents regarding the effects on structural integrity and TNAP activity using liver and osseous tissue from younger and older horses. The results of this study reveal that glyoxal-based fixatives sufficiently preserved bone tissue for successful cryosectioning without compromising TNAP activity. The method described combines the demonstration of TNAP activity with optimal preservation of tissue morphology in osseous tissue of younger and even of older mammals. As a model species, we selected horse bones in light of potentially higher similarities to ageing history and lifelong locomotion in humans as compared to other, mostly smaller, experimental model species with a much shorter life span and artificial locomotive activity when kept in cages. This may serve as a basis for future studies addressing the impact of different life traits in iconic, domestic and companion animals, which are often patients in veterinary medicine, as well as for basic research on human physiology and pathologies of the musculoskeletal system.

Diagnostic Approach to the Acute Abdomen

The acute abdomen is a term used to characterize an animal presented as an emergency, in a more or less severe critical state, and for which medical and possibly surgical treatment will be necessary. To succeed, the clinician should use a systematic approach, have an excellent knowledge of the bovine abdominal anatomy, and have a good understanding of the pathophysiology of abdominal pain. Good clinical judgment, critical analysis, and good client communication skills are also essential. This article presents and discusses those necessary skills in the context of field practice.

Mineral profile of crossbred F 1 Holstein x Gyr dairy cows during the transition period in summer and winter

ABSTRACT The transition period is often a great challenge for dairy cows and mineral imbalances are frequent. With the aim to better understand the mineral profile of F1 Holstein x Gyr dairy cows and their performances under the different conditions of summer and winter, we collected blood samples to measure calcium, magnesium and phosphorus. Samplings were performed during summer and winter, on 15 and 13 pluriparous F1 Holstein x Gyr dairy cows, respectively. Blood sampling started 4 weeks prior to the expected calving date until 30 days postpartum. The mean concentrations of all three minerals had a different pattern during the transition period in each season, representing the interaction time x season. Calcium concentration was lower in winter and more animals suffered from subclinical hypocalcemia (100%) then in summer (38.46%). Magnesium concentration was also lower in winter and 46.67% of animals had hypomagnesemia, contributing for the higher hypocalcemia frequency observed in the same season. A high proportion of animals had hyperphosphatemia what can represent an environmental problem and more attention should be given to it. The high frequency of animals with subclinical hypocalcemia is alarming once that can lead to greater consequences.

Comparison of Various Indices of Energy Metabolism in Recumbent and Healthy Dairy Cows

Background

Downer cow syndrome (DCS) is often diagnosed in dairy cattle during the early post-partum period. The etiology of this condition is not completely understood, as it can be related to the energetic or electrolyte metabolism, as well as to infectious diseases or to trauma.

Hypothesis/Objectives

The aim of this study is to compare energy metabolism and insulin sensitivity indices and various biochemical parameters between recumbent and healthy dairy cows.

Animals

A prospective study has been undertaken on 361 recumbent and 80 healthy Holstein cows.

Methods

Plasmatic glucose, insulin, non-esterified fatty acid (NEFA) and β-hydroxybutyrate (BHB) were assayed in all cows in order to calculate the insulin sensitivity indices but also minerals (Calcium, Phosphorous and Magnesium), thyroxin and creatine kinase. Body Condition Scores (BCS) was assessed.

Results

Significant differences in NEFA, and the glucose and insulin sensitivity indices (“Homeostasis Model Assessment” HOMA, “Revised Quantitative Insulin Sensitivity Check Index” RQUICKI, RQUICKI-BHB) were observed between healthy and recumbent cows in the early post-parturient period indicating disturbances of glucose and insulin homeostasis in the recumbent cows. In the same manner, mineral concentrations were significantly different between healthy and recumbent cows. Glucose, insulin NEFA, and HOMA, were different between early post-partum downer cows and the DCS-affected cows later in lactation.

Conclusion and clinical importance

Results indicate disturbances in energy homeostasis in DCS-affected dairy cows. Further research should determine a prognostic value of the indices in cows suffering from recumbency of metabolic origin.

New candidate markers of phosphorus status in beef breeder cows

Determining the phosphorus (P) status of cattle grazing P-deficient rangelands in northern Australia is important for improving animal production in these areas. Plasma inorganic P concentration is currently the best diagnostic marker of dietary P deficiency in growing cattle but is not suitable for assessing the P status of breeder cows, which often mobilise substantial bone and soft tissue reserves in late pregnancy and lactation. Markers of bone turnover offer potential as markers of P status in cattle, as they reflect bone mobilisation or bone formation. Recent experiments investigating the physiology of beef breeder cows during diet P deficiency have indicated that the ratio of plasma total calcium concentration to plasma inorganic P concentration might be suitable as a simple index of P deficiency. However, a more specific measure of increased bone mobilisation in P-deficient breeders is plasma concentration of C-terminal telopeptide of Type 1 collagen. Also, plasma concentration of bone alkaline phosphatase is a marker of defective bone mineralisation in dietary P deficiency. These candidate markers warrant further investigation to determine their predictive value for P deficiency in cattle.

Genetic parameters of subclinical macromineral disorders and major clinical diseases in postparturient Holstein cows

The main objective of this study was to assess the genetic parameters of subclinical disorders associated with subclinical hypocalcemia, hypophosphatemia, subclinical hypomagnesemia, hypokalemia, and hyperphosphatemia, as well as major clinical diseases after calving in Holstein cows. The secondary objective was to estimate the associated genetic and phenotypic correlations among these subclinical and clinical conditions after calving in Holstein cows. The study was conducted in 9dairy herds located in Northern Greece. None of the herds used any kind of preventive measures for milk fever (MF). A total of 1,021 Holstein cows with pedigree information were examined from November 2010 until November 2012. The distribution across parities was 466 (parity 1), 242 (parity 2), 165 (parity 3), and 148 (parity 4 and above) cows. All cows were subjected to a detailed clinical examination and blood was sampled on d 1, 2, 4, and 8 after calving. Serum concentrations of Ca, P, Mg, and K were measured in all samples, whereas β-hydroxybutyrate (BHB) was measured only for d 8. The final data set included 4,064 clinical and 16,848 biochemical records (4,020 Ca, 4,019 P, 4,020Mg, 3,792K, and 997 BHB). Data of 1,988 observations of body condition score at d 1 and 8 were also available. All health traits were analyzed with a univariate random regression model. The genetic analysis for macromineral-related disorders included 986 cows with no obvious signs of MF (35 cows with MF were excluded). Analysis for other health traits included all 1,021 cows. A similar single record model was used for the analysis of BHB. Genetic correlations among traits were estimated with a series of bivariate analyses. Statistically significant daily heritabilities of subclinical hypocalcemia (0.13-0.25), hypophosphatemia (0.18-0.33), subclinical hypomagnesemia (0.11-0.38), and hyperphosphatemia (0.14-0.22) were low to moderate, whereas that of hypokalemia was low (0.08-0.10). The heritability of body condition score was 0.20±0.10. Statistically significant daily heritabilities of clinical diseases were those of MF (0.07-0.11), left displaced abomasum (0.19-0.31), and mastitis (0.15-0.41). Results suggest that these health disorders are heritable traits and could be minimized with proper genetic selection. Statistically significant phenotypic correlations were estimated for the first time between macromineral concentrations and almost all transition cow metabolic and infectious health disorders.

The effect of transient, moderate dietary phosphorus deprivation on phosphorus metabolism, muscle content of different phosphorus-containing compounds, and muscle function in dairy cows

Hypophosphatemia is a common finding in periparturient and anorectic cattle. Although the clinical relevance of hypophosphatemia in cattle is uncertain, it has been empirically associated with persistent recumbency, specifically in periparturient dairy cows. The objective of the present study was to determine if transient dietary phosphorus (P) deprivation over a course of 5 wk, by feeding an approximately 40% P-deficient ration to lactating dairy cows, would result in altered muscle function or muscle P metabolism severe enough to present a risk for animal health and well-being. In addition, we wanted to determine the association between the plasma phosphate concentration ([Pi]) and muscle tissue P content to assess to what extent intracellular P deprivation of muscle cells could be extrapolated from subnormal plasma [Pi]. Ten healthy multiparous, mid-lactating dairy cows received a ration with a P content of 0.18% over a period of 5 wk. Following the P-deprivation phase, the same ration supplemented with P to obtain a dietary P content of 0.43% was fed for 2 wk. Blood and urine samples were collected regularly and muscle biopsies were obtained repeatedly to determine the P content in muscle tissue. Function of skeletal and heart muscles was evaluated by electrocardiography and electromyography conducted repeatedly throughout the study. Feeding the P-deficient ration resulted in the rapid development of marked hypophosphatemia. The lowest plasma [Pi] were measured after 9 d of P depletion and were, on average, 60% below predepletion values. Plasma [Pi] increased thereafter, despite ongoing dietary P depletion. None of the animals developed clinical signs commonly associated with hypophosphatemia or any other health issues. Urine analysis revealed increasing renal calcium, pyridinoline, and hydroxypyridinoline excretion with ongoing P deprivation. Biochemical muscle tissue analysis showed that dietary P depletion and hypophosphatemia were not associated with a decline in muscle tissue P content. Electromyographic examination revealed increased occurrence of pathological spontaneous activity in striated muscles after 2 wk of dietary P depletion in several cows, which could be suggestive of neuromuscular membrane instability. No effect on heart muscle activity was identified electrocardiographically. These results suggest that counter-regulatory mechanisms were sufficient to maintain normal muscle tissue P content during transient and moderate P deprivation. Muscle function was not grossly affected, although the increased occurrence of pathological spontaneous activity suggests that subclinical neuropathy or myopathy, or both, may have occurred with ongoing P deprivation. The results presented here indicate that plasma [Pi] is unsuitable for assessing muscle tissue P content in cattle.

Blood biochemical values in Japanese Black breeding cows in Kagoshima Prefecture, Japan

To obtain blood biochemical basic data of Japanese Black breeding cows in Kagoshima Prefecture, Japan, blood samples were obtained from 857 clinically healthy multiparous cows on 71 farms. Cows were divided into three stages: the prepartum stage (between 20 and 80 days before parturition, n=290), lactation stage (between 20 and 80 days after parturition, n=283) and maintenance stage (between 120 and 200 days after parturition, n=284). The mean concentration of total protein and total cholesterol, and the mean activities of aspartate aminotransferase in the lactation stage tended to be higher than those in the prepartum and maintenance stages. The mean concentration of glucose in the prepartum stage tended to be lower than that in the lactation and the maintenance stages. The mean concentration of nonesterified fatty acids and beta-hydroxybutyrate in the prepartum stage tended to be higher than those in the lactation and maintenance stages. The mean concentration of serum retinol was approximately 30 µg/dl in all stages. These results suggest that the blood biochemical values of multiparous Japanese Black cows vary with breeding stages, and it is considered that the blood parameters obtained in this study are useful as indices for health management of Japanese Black breeding cows.

Avaliação do perfil metabólico de vacas da raça Holandesa durante o período de transição

O período de transição é um momento de grande desafio para vacas de aptidão leiteira, uma vez que, a maioria dos problemas metabólicos ocorre nesta fase podendo prejudicar toda a expectativa de produção durante a lactação, resultando em impacto econômico significativo para fazendas de produção de leite. Este trabalho teve como objetivo avaliar o perfil metabólico de vacas da raça Holandesa durante o período de transição. Doze vacas Holandesas foram avaliadas, três semanas pré-parto até três semanas pós-parto, em sistema free-stall, localizado em Inhaúma, Minas Gerais, no período de outubro a dezembro de 2012. Avaliou-se o perfil metabólico através da concentração sérica de ácidos graxos não esterificados (AGNE), beta hidroxibutirato (BHBA), colesterol (COLES), proteína total (PT), albumina (ALB), cálcio, fósforo, magnésio bem como a atividade sérica das enzimas aspartato transaminase (AST) e lactato desidrogenase (LDH). As concentrações séricas de AGNE e BHBA foram diferentes entre o pré-parto e pós-parto (p<0,05). Observou-se diminuição na concentração de COLES com a aproximação do parto com posterior aumento (p<0,05). As concentrações séricas dos minerais, PT e ALB não apresentaram diferenças (p>0,05) no período avaliado. A atividade enzimática de AST e LDH foram maiores no período pós-parto (p<0,05). A avaliação do perfil metabólico é uma importante ferramenta de monitoramento e, na situação estudada, demonstrou alterações do perfil energético das vacas entre os períodos pré e pós-parto, relacionadas provavelmente a diminuição da ingestão de alimentos. A luz dos resultados do perfil metabólico, o rebanho avaliado possui pequeno risco para a ocorrência de enfermidades no pós-parto relacionadas ao período de transição

Perfil mineral de vacas mestiças Girolanda no período de transição em sistema semi-intensivo em duas estações do ano

Neste estudo foi avaliado o perfil metabólico de vacas leiteiras no período de transição durante o verão e o inverno. Foram utilizados 31 animais pluríparos mestiços girolando em cada estação, totalizando 62 vacas. No verão permaneciam em pasto com suplementação de silagem de milho e concentrado. No inverno, a exigência nutricional era suprida apenas com silagem de milho e concentrado. Foram feitas um total de 11 coletas de sangue de cada animal segundo o seguinte protocolo: quatro coletas pré-parto espaçadas semanalmente, no dia do parto e com 2, 5, 10, 15, 21 e 30 dias pós-parto. Foram avaliadas as concentrações de cálcio, fósforo e magnésio. Todos os analitos variaram em função do estatus fisiológico. As concentrações médias de cálcio e magnésio foram maiores no verão do que no inverno. Em ambas as estações, as menores concentrações médias de cálcio ocorreram próximas ao parto, sendo que 75% dos animais no inverno e 35,48% dos animais no verão estavam hipocalcêmicos. Apenas no décimo dia as concentrações de cálcio voltaram aos níveis do pré-parto, demonstrando que esse tempo é necessário para a adaptação da nova condição de lactante. As concentrações de magnésio foram menores no pós-parto do que no pré-parto nas duas estações, demonstrando a necessidade desse mineral para a produção de leite. As concentrações médias de magnésio permaneceram sempre dentro dos valores de referência, porém 19% dos animais aos dois dias pós-parto no inverno e 7% dos animais aos 10 dias pós-parto no verão tinham concentrações inferiores a esses limites. As concentrações de fósforo sofreram grande variação ao longo do peri-parto, porém sempre em níveis elevados, sendo que 49,8% dos animais no inverno e 37,3% no verão tinham níveis de fósforo acima dos valores de referência

Managing the grazing dairy cow through the transition period: a review

The transition period of the dairy cow generally refers to the last three weeks of gestation and the first three weeks of lactation. During this period, the dairy cow faces numerous physiological challenges, requiring both homeostatic and homeorhetic changes to support the demands of lactation. Management strategies to achieve a successful transition have developed over many decades. Historically, these strategies focussed on achieving high energy intakes pre-calving in an attempt to improve post-calving metabolism; however, more recent research has indicated that this approach may not be appropriate. Physiological and molecular data have indicated that imposing a slight negative energy balance (EBAL) pre-calving can improve post-calving EBAL, metabolic health indices and milk production. It was hypothesised that the challenges of the transition period would be less in a grazing system than in an intensive confinement system, due to the lower milk production and the difference in population density and, therefore, pathogen exposure. However, the molecular and immunological responses to the change of state are similar in magnitude in a moderate-yielding pasture-fed cow and in a high-yielding cow fed a total mixed ration. The collective data point to a peripartum immunosuppression, which is affected by body condition score and feeding level. This review will outline the literature and provide an assessment of the most recent transition cow management for grazing dairy cows.

Effect of supranutritional organic selenium supplementation on postpartum blood micronutrients, antioxidants, metabolites, and inflammation biomarkers in selenium-replete dairy cows

Dairy cows have increased nutritional requirements for antioxidants postpartum. Supranutritional organic Se supplementation may be beneficial because selenoproteins are involved in regulating oxidative stress and inflammation. Our objective was to determine whether feeding Se-yeast above requirements to Se-replete dairy cows during late gestation affects blood micronutrients, antioxidants, metabolites, and inflammation biomarkers postpartum. During the last 8-weeks before calving, dairy cows at a commercial farm were fed either 0 (control) or 105 mg Se-yeast once weekly (supranutritional Se-yeast), in addition to Na selenite at 0.3 mg Se/kg dry matter in their rations. Concentrations of whole-blood (WB) Se and serum Se, erythrocyte glutathione (GSH), and serum albumin, cholesterol, α-tocopherol, haptoglobin, serum amyloid A (SAA), calcium, magnesium, phosphorus, non-esterified fatty acids, and β-hydroxybutyrate were measured directly after calving, at 48 h, and 14 days of lactation in 10 cows of each group. Supranutritional Se-yeast supplementation affected indicators of antioxidant status and inflammation. Cows fed a supranutritional Se-yeast supplement during the last 8-weeks of gestation had higher Se concentrations in WB (overall 52 % higher) and serum (overall 36 % higher) at all-time points, had higher SAA concentrations at 48 h (98 % higher), had higher erythrocyte GSH (38 % higher) and serum albumin concentrations (6.6 % higher) at 14 days, and had lower serum cholesterol concentrations and higher α-tocopherol/cholesterol ratios at calving and at 48 h compared with control cows. In conclusion, feeding Se-replete cows during late gestation a supranutritional Se-yeast supplement improves antioxidant status and immune responses after calving without negatively impacting other micronutrients and energy status.

Treatment of phosphorus balance disorders

Phosphorus (P) homeostasis in ruminants has received increased attention over the past decades. Although environmental concerns associated with excessive P excretion in cattle manure have led to incentives to lower dietary P intake, hypophosphatemia-particularly in the periparturient dairy cow-has been associated with conditions, such as the downer cow syndrome or postparturient hemoglobinuria. The objective of this article is to revisit current understanding of P homeostasis in ruminants, to discuss the pathophysiology and clinical presentation of P balance disorders, and to review different treatment approaches to correct imbalances of the body's P equilibrium.

Survey on the occurrence of milk fever in dairy cows and the current preventive strategies adopted by farmers in New South Wales, Australia

OBJECTIVE

The aim of this study was to investigate general and specific strategies adopted by New South Wales (NSW) farmers to prevent milk fever (MF) and its occurrence at calving within their dairy herds.

DESIGN AND METHODS

Of 300 dairy farmers in NSW randomly chosen and sent questionnaires, descriptive analysis of the returned data was performed for 102 questionnaires. To identify the various strategies used to prevent MF and its incidence, farms were classified as having a low (<3%) or high (>3%) incidence of MF. The data were analysed using a multivariable logistic regression model and backwards stepwise elimination to identify significant preventive strategies adopted by farmers having a low or high incidence of MF.

RESULTS

Based on the 102 responses, the median incidence of MF in the NSW dairy region was 3% (range 0-30%). The farms with low MF incidence practised specific MF control strategies, such as feeding dry cows separately, grain supplementation and feeding a low-potassium ration before calving and using a commercial ration mix immediately after calving. The time to first milking post-calving was on average 13.6 h on the low-incidence farms compared with 21.1 h on the high-incidence farms.

CONCLUSIONS

The low median incidence of MF (3%) in NSW was probably related in part to awareness of the importance of feeding a low-potassium, high-grain diet before calving. However, the incidence of MF was high on the farms not practising specific MF preventive methods.