Influence of different calcium concentrations in the diet on bone metabolism in growing dairy goats and sheep

The purpose of this study was to investigate, if different Ca concentrations in diets have an influence on bone mineral metabolism in growing goats and sheep. Twelve growing goats and sheep were divided into two groups. The two control groups received 6.1 g calcium/day (nG) and 6.7 g calcium/day (nS) for goat and sheep respectively. The other two groups were fed 17.7 g calcium/day (hG) and 18.5 g calcium/day (hS). Blood samples were taken 2, 4, 5 and 6 weeks after the start of the experiment. In serum Ca and vitamin D were determined and bone metabolism was measured using crosslinked carboxyterminal telopeptide of type I collagen (ICTP), crosslaps, bone-specific alkaline phosphatase and osteocalcin (OC). Bone mineral density (BMD) was quantified using quantitative computed tomography. Bone resorption marker (ICTP) concentrations were significantly different between both groups control sheep/control goat and hS/hG, but no significant differences were evident in the different feeding groups within one species. OC concentrations showed a similar course to ICTP. The goats had significantly higher concentrations compared with sheep. The 1,25 dihydroxyvitamin D (VITD) concentrations in both hCa groups were significantly lower than in the control groups. BMD increased in the hCa groups compared with the control groups with the time, but significant differences were only evident in sheep in week 2. The hCa diet did not induce differences between the groups within one species for all bone markers. The control Ca diet seems to improve the active Ca absorption via VITD whereas the hCa diet leads to a higher amount of Ca apparently digested. Higher BMD was only observed in group hS compared with nS.     

Effect of a commercial anionic dietary supplement on urinary pH and concentrations of electrolytes and pH in blood of horses

ABSTRACT

Aims: To compare urine urinary pH, blood pH and concentration of electrolytes in blood of healthy horses fed an anionic salt supplement to achieve diets with a dietary cation-anion difference (DCAD) of ?40 or 0?mEq/kg DM, with horses a fed a diet with a DCAD of 85?mEq/kg DM.

Methods: Eight healthy horses received each of three diets in a randomised crossover design. Diets consisted of grass hay and concentrate feed, with a varying amount of an anionic supplement to achieve a DCAD of 85 (control), 0 or ?40?mEq/kg DM. They were fed for 14 days each with a washout period of 7 days between. Urine pH was measured daily and blood samples were collected on Days 0, 7 and 14 of each study period for the measurement of pH and concentration of electrolytes.

Results: Four horses voluntarily consumed the anionic supplement with their feed, but four horses required oral supplement administration via dose syringe. During the study period mean urine pH was lower in horses fed diets with a DCAD of 0 (6.91; SD 0.04) and ?40 (6.83; SD 0.04) mEq/kg DM compared to the control diet (7.30; SD 0.04). Compared with horses fed the control diet, mean urine pH was lower in horses fed the 0 and ?40?mEq/kg DM diets on Days 1–12 and 14 (p?<?0.05) of the study period. On Day 13 it was only lower in horses fed the ?40?mEq/kg DM diet (p?<?0.01). Urine pH was similar for horses fed the 0 and ?40?mEq/kg DM diets (p?=?0.151). The DCAD of the diet had no effect on blood pH, ionised Ca or anion gap. Mean concentrations of bicarbonate in blood were affected by diet (p?=?0.049); they were lower when horses were fed the 0?mEq/kg diet relative to the control diet on Day 14.

Conclusions and clinical relevance: The anionic supplement reduced urine pH in horses fed diets with a DCAD of 0 or ?40?mEq/kg DM compared with 85?mEq/kg DM. However as urinary pH did not fall below pH 6.5, the pH below which calcium carbonate uroliths do not form, this reduction in urine pH is unlikely to be clinically significant. The supplement was variably palatable and showed minimal promise as an effective urinary acidifier at the doses administered in this study.     

Effects of dietary strong acid anion challenge on regulation of acid-base balance in sheep

The acid-base status of the extracellular fluid is directly affected by the concentrations of strong basic cations and strong acid anions that are absorbed into the bloodstream from the diet. The objective of this study was to develop and characterize a model for dietary acid challenge in sheep by decreasing the dietary cation-anion difference (DCAD) using NutriChlor (HCl-treated canola meal), an anionic feed supplement. Ten fully fleeced sheep (Rideau-Arcott, 54.3 +/- 6.7 kg of BW) were fed either a control supplement [200 g/d of canola meal, DCAD = 184 mEq/kg of DM, calculated as (Na+ + K+) - (Cl- + S2-)] or an anionic supplement (AS; 200 g/d of NutriChlor, DCAD = -206 mEq/kg of DM) offered twice daily at 0700 and 1100 in a randomized complete block design. The sheep were individually housed and limit-fed a basal diet of dehydrated alfalfa pellets (22% CP and 1.2 Mcal of NE(g)/kg, DM basis) at 1.1 kg of DM/d offered twice daily at 1000 and 1300. Two days before the beginning of the experiment, the sheep were fitted with vinyl catheters (0.86-mm i.d., 1.32-mm o.d.) in the left jugular vein to facilitate blood sampling. Blood and urine samples were obtained daily from 1100 to 1130 on d 1 through 9 and at 0700, 1000, 1300, 1600, and 1900 on d 10. Blood was analyzed for hematocrit, plasma pH, gases, strong ions, and total protein. Urine samples were analyzed for pH. The AS induced a nonrespiratory acid-base disturbance associated with lower (P < 0.05) plasma pH (7.47 vs. 7.39), lower (P < 0.05) urine pH (8.13 vs. 6.09), and lower (P < 0.05) strong ion difference (42.5 vs. 39.5). The AS reduced (P < 0.05) the concentration of plasma glucose, base excess, and bicarbonate and increased (P < 0.05) the concentration of K+ and Cl-. Lowering DCAD increased (P < 0.05) Ca2+ concentrations in plasma by 13%. In conclusion, this dietary model successfully induced a significant acid-base disturbance in sheep. Although the acidifying effects of negative DCAD in the diet may have short-term prophylactic effects of elevating the concentration of Ca2+ in plasma, negative DCAD may have detrimental effects on acid-base balance.     

Nutrient intake, acid base status and growth performance of growing male buffalo calves fed varying level of dietary cation anion difference

Influence of + 110, + 220 and + 330 mEq/kg of dry matter (DM) dietary cation anion difference (DCAD) on growth performance of growing male buffalo calves was examined in a randomized complete block design. Three DCAD diets were randomly allotted to three groups, ten calves in each group. A linear increase in nutrient intake was recorded with increased DCAD level. However, digestibilities of nutrients remained unaltered across all diets. Calves fed + 330 DCAD diet had higher nitrogen balance than those fed + 110 DCAD diet. Blood pH and serum HCO₃ increased with increased DCAD level. Serum chloride was high in calves fed + 110 DCAD diet, while serum (Na + K) − (Cl + S) increased linearly with increased DCAD level. Serum calcium increased with decreased DCAD level while serum magnesium and phosphorus remained unaffected. Ca balance remained unaltered by calves fed varying level of DCAD. Urine pH increased with increased DCAD level. Calves fed + 220 and + 330 DCAD diets gained more weight than those fed + 110 DCAD diet. In conclusion, increased DCAD level not only increased dry matter intake but also weight gain in growing buffalo calves.     

Bone metabolism of milk goats and sheep during second pregnancy and lactation in comparison to first lactation

Substantial losses of skeletal tissue occur during late pregnancy and lactation. The goal of the present study was to follow these changes in pregnant and lactating goats and sheep, compare these two species during their second lactation, and also compare the results to the first lactation. Blood samples were collected from 12 adult dairy goats (Saanen goat) and sheep (Ostfriesen milk sheep) monthly during gestation, 2 or 3 days postpartum (pp), 2 weeks pp, 4 weeks pp, and then monthly during lactation until 7 months after parturition. Total bone mineral content (BMC) and total bone mineral density (BMD) were quantified using peripheral quantitative computed tomography (pQCT) at the same intervals as the blood was taken. Bone resorption was assessed in serum using two different domains of the carboxyterminal telopeptide of type I collagen (ICTP and crosslaps). Bone formation was quantified in serum with osteocalcin (OC) and bone-specific alkaline phosphatase (bAP). In addition, Ca and 1,25 dihydroxy vitamin D (VITD) were determined in serum. The same procedure was done during the first and second gestation and lactation. Mean ICTP and crosslaps concentrations of the two animal species showed an increase in the last month of gestation. In contrast, mean OC concentrations decreased slowly from the 2nd month of pregnancy until the first week pp. Also mean bAP activities showed a similar time course. Total BMC and BMD decreased until the first week pp in both species. Afterwards, BMC increased again during lactation. BMD levels of sheep and goats returned to prepartum levels during lactation. Vitamin D concentrations peaked in the first week pp. Only VITD concentrations in goats stayed elevated compared with prepartum values throughout the whole lactation during the second lactation. Around parturition and at the beginning of lactation, the bone resorptive phase of bone remodelling is accelerated, but is uncoupled from the process of bone formation. The mineral decrease in bone of these lactating animals seems to be reversible. Since during lactation, bone remodelling has bone resorption and formation phases tightly coupled. Interestingly, in these species, the bone loss in the second pregnancy and lactation measured with BMC and BMD is not as prominent as in the first lactation, but shows almost the same course, although the animals gave more milk in the second lactation. It seems that the organism adapts to the circumstances more easily in the second lactation compared to the first lactation in these two species.     

Effect of dietary cation-anion difference on urinary pH, feedlot performance, nitrogen mass balance, and manure pH in open feedlot pens

Six experiments were conducted to evaluate dietary cation-anion difference (DCAD) in concentrate diets on urinary pH, feedlot performance, and N mass balance. In Exp. 1, 15 wether lambs (33.5 ± 3.0 kg) in five 3 × 3 Latin squares were fed a basal diet of 82.5% dry-rolled corn (DRC), 7.5% alfalfa hay, 5% molasses, and 5% supplement with different proportions of anionic and cationic salts. The DCAD was -45, -24, -16, -8, 0, +8, +16, +24, +32, and +40 mEq per 100 g of DM with the control basal diet (DCAD = +8) included in each square. Urinary pH increased (cubic, P < 0.01) as DCAD increased and DMI increased linearly (P < 0.01) with increasing DCAD. In Exp. 2 and 3, 8 Holstein steers (312 ± 24 kg) were used in 2 consecutive 4 × 4 Latin squares. Steers were fed either the same basal diet as Exp. 1 or a basal diet with 20% wet distillers grains (WDGS) replacing DRC. In Exp. 2, DCAD was adjusted to -2, -12, and -22 mEq per 100 g of DM from the basal diet (DCAD = +8) and DCAD was adjusted in Exp. 3 to -12, -22, and -32 mEq per 100 g of DM from the basal WDGS diet (DCAD = -2). Urinary pH decreased linearly as DCAD decreased (P < 0.01) in both experiments, whereas DMI decreased linearly in Exp. 2 (P = 0.02) but not Exp. 3 (P = 0.96). In Exp. 4, 6 crossbred steers (373 ± 37 kg) were used in a 2-period crossover design. Steers were fed the same basal diet as Exp. 3 with DCAD of -16 (NEG) and +20 (POS) mEq per 100 g of DM. Urinary pH and DMI (P < 0.05) were less for cattle fed the NEG diet compared with POS. In 2 experiments, steers (n = 96 each) were fed NEG or POS as calves (260 ± 22 kg of BW) for 196 d from November to May (Exp. 5) or as yearlings (339 ± 32 kg of BW) for 145 d from June to October (Exp. 6). Final BW, DMI, ADG, and HCW were not different (P > 0.11) among treatments in either experiment. Efficiency of BW gain was increased (P = 0.05) for steers fed NEG compared with POS in Exp. 5 but was not different (P = 0.11) in Exp. 6. Amount of N intake, retention, excretion, and manure N (kg/steer) were not different (P > 0.11) among treatments in either experiment. Manure pH (soil, feces, and urine) was decreased (P < 0.01) in pens fed NEG compared with POS in both experiments. Amount of N lost (kg/steer) was not different (P = 0.44) in Exp. 5, but tended (P = 0.09) to be 10.6% greater for POS compared with NEG in Exp. 6. Urinary pH was decreased by reducing DCAD, but this had minimal effect on N losses in open feedlot pens in these experiments.     

Effects of anionic salts supplementation on blood pH and mineral status, energy metabolism, reproduction and production in transition dairy cows

The objectives of this study were to determine the effects of a pre-partum diet with lower than recommended (DCAD = −82 mEq/kg of dietary DM) amounts of anionic salts on metabolism, health, reproductive performance and milk production in dairy cows. Sixty Holstein multiparous cows were enrolled 21 days prior to expected calving date. The animals were randomly assigned to receive one of two rations: 30 cows received anionic ration [−82 mEq (NA + K − Cl − S)/kg of DM] for 21 d to parturition and the other group (n = 30) were fed a usual dry period ration (+192 mEq/kg of DM). Serum samples obtained at days −21, +3 and +21 relative to calving were analyzed for β-hydroxybutyrate (BHBA), non-esterified fatty acids (NEFA), glucose, calcium (Ca), inorganic phosphorus, magnesium, chloride, sodium, potassium, cholesterol, urea, creatinine, total protein, albumin, and aspartate aminotransferase (AST). Urine pH declined from 8.4 at 21 d before calving (pre-treatment) to 6.2 at day 7 pre-partum in the treatment group. Repeated-measure mixed model analysis indicated that the concentrations of Ca were significantly increased and creatinine, and AST were significantly decreased by lowering DCAD. The concentrations of BHBA, NEFA and glucose were not affected by treatment. The incidence of milk fever and culling were 5 and 11 times higher in the control group in comparison with the treatment group, respectively. The intervals from calving to first breeding and to pregnancy were not influenced by treatment. There was no group effect on average daily milk yield or fat percentage.     

Influence of varying dietary cation anion difference on serum minerals, mineral balance and hypocalcemia in Nili Ravi buffaloes

The study was conducted to examine the influence of diets containing − 110, + 110, + 220 and + 330 mEq/kg dry matter (DM) of dietary cation anion difference (DCAD) on serum minerals, minerals balance (Na, K, Cl, S, Ca, Mg and P) and hypocalcemia in prepartum Nili Ravi buffaloes in a randomized complete block design during summer. Four DCAD diets were randomly allotted to four groups, five buffaloes in each group. A linear increase in nutrients intake was recorded with increasing the DCAD level. Buffaloes fed − 110 DCAD diet had higher nutrients digestibilities than those fed + 110, + 220 and + 330 DCAD. Blood pH and serum HCO₃ also increased linearly with increasing DCAD level. Serum Cl was high in buffaloes fed the − 110 DCAD diet, while serum cation anion difference increased linearly with increasing the DCAD level. Serum Ca increased with decreasing the DCAD level while serum Mg, P and S remained unaffected. Urine pH increased with increasing DCAD level. A constant increase in urinary excretion of Ca, Mg, P and Cl was observed with decreasing the DCAD level. Buffaloes fed − 110 DCAD diet had increased Ca and Cl balance while Mg, P and S balance remained unaltered due to DCAD alteration. Not a single case of hypocalcemia was observed in buffaloes fed − 110 and + 110 DCAD diets. However, one buffalo from each group fed + 220 and + 330 DCAD diets had hypocalcemia. This study indicated that − 110 and + 110 DCAD diets not only increased calcium balance but also prevented hypocalcemia in Nili ravi buffaloes.     

Influence of varying levels of dietary cation anion difference on ruminal characteristics,nitrogen metabolism and in situ digestion kinetics in buffalo bulls

This study was conducted to examine the influence of varying dietary cation anion difference (DCAD) on nutrient intake, digestibility, ruminal characteristics, blood acid base status and in situ digestion kinetics in Nili Ravi buffalo bulls. Four iso‐nitrogenous and iso‐caloric diets having ?110, +110, +220 and +330 mEq/kg dry matter (DM) DCAD were formulated which were represented by A (anionic), LC (low cationic), MC (medium cationic) and HC (high cationic), respectively. These diets were used in four ruminally cannulated Nili Ravi buffalo bulls in a 4 × 4 Latin Square Design. Improved nutrient intake was recorded at high DCAD levels while digestibility remained unaffected. Ruminal ammonia nitrogen, rumen pH, acetate and acetate : propionate ratio were higher in buffalo bulls fed MC and HC diets than those fed A and LC diets. Blood pH and HCO₃^‐ also tended to increase as DCAD level was increased in the diet. Serum Ca and Cl concentrations were higher in bulls fed A and LC diets whereas serum Mg, P and S remained unaffected. Urine pH increased with increasing DCAD level. Nitrogen intake and blood urea nitrogen concentrations were also higher in bulls fed MC and HC diets. There was a consistent increase in ruminal DM and neutral detergent fiber degradability, rate of disappearance and extent of digestion at high DCAD levels in the diet. However, lag time decreased at high DCAD level. This study indicated that buffalo bulls fed MC and HC diets improved feed intake, ruminal characteristics and digestion kinetics.     

Long-term effects of dietary anion-cation balance on acid-base status and bone morphology in reproducing ewes

The beneficial effects of anionic salts on calcium metabolism have been shown by supplementing rations with such salts during the last 3 weeks of pre-partum. However, there are few reports on the effects of anionic salts supplementation for periods of 4 weeks or longer on acid-base status, mineral metabolism and bone morphology. This study was conducted to evaluate the effects of the long-term dietary supplementation of anionic salts on the acid-base status, plasma minerals concentrations and bone morphology in sheep. Twenty-seven twin-bearing sheep were assigned to two experimental groups and a control group, depending on dietary cation-anion difference (DCAD) (+272.6, -88.9 and + 164.5 mEq/kg DM, respectively). Sheep assigned to each dietary treatment received their respective rations beginning 6 weeks prepartum and continuing until 12 days post-partum. Diets containing anionic salts induced a mild metabolic hyperchloraemic acidosis from 1 week pre-partum to 2 days post-partum that was completely compensated by non-respiratory mechanisms. These changes on acid-base status were accompanied by an increase of plasma ionized calcium levels. Plasma total calcium, phosphorus and magnesium concentrations were not affected by dietary treatment. Parathyroid hormone concentrations were related to the concentration of ionized calcium of plasma and were higher in sheep fed the cationic diet. Plasma osteocalcin levels were increased in sheep fed the anionic diet and cortical bone remodelling occurred in all the animals during late pregnancy in light and electron microscopy observation, but was particularly evident in the sheep fed the anionic diet. Bone turnover might be stimulated because of the role of the bone in buffering systemic acidosis. The data suggest that anionic salts ameliorated calcium metabolism around parturition by increasing bone resorption and the concentration of ionised calcium in plasma, possibly mediated by a mild hyperchloraemic metabolic acidosis induced by the salts.     

Influence of altering dietary cation anion difference on milk yield and its composition by early lactating Nili Ravi buffaloes in summer

Influence of − 11, + 11, + 22 and + 33 mEq/100 g dry matter (DM) of dietary cation anion difference (DCAD) on dry matter intake (DMI), serum concentration of minerals and milk yield and its composition by early lactating Nili Ravi buffaloes was examined in a randomized complete block design during summer. Four iso-energetic and iso-nitrogenous DCAD diets were randomly allotted to four groups, five buffaloes in each group. A linear increase in DMI and water intakes was recorded with increasing the DCAD concentration. Greater nitrogen balance was noticed in buffaloes fed diets containing + 22 and + 33 mEq/100 g DM DCAD than those fed − 11 and + 11 mEq/100 g DM DCAD concentrations. Blood pH and HCO₃ concentration increased linearly with increasing DCAD concentrations. Serum chloride concentration was greater with − 11 mEq/100 g DM DCAD concentration, while serum cation anion difference increased linearly with increasing the DCAD concentration. Serum calcium concentration increased significantly with decreasing the DCAD concentration while serum magnesium and phosphorus concentrations remained unaffected. Buffaloes fed − 11 DCAD had higher calcium and chloride balance than those fed + 11, + 22 and + 33 DCAD. Phosphorus, sodium and potassium balance increased in buffaloes fed high (+ 22 and + 33) DCAD. Urine pH was increased significantly with increasing DCAD concentration. Milk yield and milk fat percentage increased linearly with DCAD concentration, whereas milk protein and lactose content were not affected. Increasing DCAD from − 11 to + 33 mEq/100 g DM increased DMI, water intake, milk yield and milk fat content in early lactating buffaloes during summer.     

阴离子饲粮对活体外瘤胃发酵特性和营养物质消化的影响

应用双外流连续培养系统模拟瘤胃发酵,研究不同阴阳离子差(DCAD)水平的阴离子饲粮对活体外瘤胃发酵和营养物质消化率的影响。试验分2期进行,每期12个发酵罐,3个1组,分别投入4种不同DCAD水平的饲粮:+120-、9-、77-、145 mEq/kgDM,后3种饲粮通过添加阴离子添加剂降低DCAD。结果表明:①阴离子饲粮对瘤胃发酵pH值、氨态氮浓度、总挥发性脂肪酸浓度、主要挥发酸的摩尔比例均没有显著影响(P>0.2)。②对饲粮干物质、有机质、中性洗涤纤维、粗蛋白消化率没有显著影响(P>0.2)。③对瘤胃微生物合成效率没有显著影响(P>0.2)。试验结论为阴离子饲粮对活体外瘤胃发酵和饲粮营养物质消化率没有显著影响。     

Effect of negative dietary cation‐anion differences on carcass characteristics and beef tenderness of Japanese Black steers

Lowering dietary cation‐anion differences (DCAD) can enhance responsiveness to Ca‐homeostatic hormones and increase Ca availability, which might have potential to activate a Ca‐dependent protease, calpain, and to enhance postmortem myofibrillar proteolysis. In this study, we investigated the effects of DCAD manipulation on calpain activity and beef tenderness in Japanese Black cattle which are characterized by their high marbling. Thirty‐six Japanese Black steers were allotted to one of two treatments: (i) control (CON; DCAD +6.09 mEq/100 g of dry matter (DM)) or (ii) negative DCAD (NEGD; DCAD ?8.27 mEq/100 g DM) for 70 days before slaughter. Lowering DCAD decreased DM and energy intake (P < 0.01) even though it did not negatively affect the growth performance or carcass characteristics. In NEGD, urine pH was decreased by acidification caused by the negative DCAD (P < 0.01). Calpain activities tended to be improved in NEGD (P = 0.09), but Warner‐Bratzler shear force values were not affected by treatment. Although calpain activities tended to improve, lowering DCAD to ?8.27 for 70 days before slaughter was insufficient to enhance beef tenderness in Japanese Black steers.     

Effects of 25-hydroxyvitamin D3 and manipulated dietary cation-anion difference on the tenderness of beef from cull native Korean cows

In this study, we characterized the effects of 25-hydroxyvitamin D3 (25-OH D3) and manipulated dietary cation-anion difference (DCAD) on the performance, urine pH, serum constituents, carcass traits, tissue residual vitamin D and its metabolites, beef tenderness, and mRNA and protein concentrations of Ca-dependent proteinases in LM using 24 cull native Korean cows. The cows were divided into 3 groups of 8: control, 25-OH D3 supplemented (25-OH D3), and manipulated DCAD plus 25-OH D3 supplemented (DCAD+25-OH D3). Cows receiving 25-OH D3 or DCAD+25-OH D3 were dosed with 125 mg of 25-OH D3 6 d before slaughter. The manipulated DCAD (-10 mEq/100 g of DM) diet was fed from 20 to 6 d (14 d) before slaughter. The DCAD+25-OH D3 treatment decreased urine pH and increased serum Ca concentrations. Although the vitamin D concentrations in LM, liver, and kidney were not affected by 25-OH D3 or DCAD+25-OH D3, muscle tissue 25-OH D3 concentrations were increased by both regimens. Serum 25-OH D3 concentrations were increased by 25-OH D3 supplementation, and the increase was even greater for DCAD+25-OH D3. The same pattern was observed for serum 1,25- (OH)2 D3. However, the LM concentration of 1,25-(OH)2 D3 was less for DCAD+25-OH D3 than for control. Although Ca concentrations of LM increased numerically in response to 25-OH D3 supplementation, no statistical differences in Warner-Bratzler shear force or sensory traits of LM were detected. The LM of cows receiving 25-OH D3 with or without manipulated DCAD had greater concentrations of mu-calpain and m-calpain mRNA, whereas the reverse was observed for calpastatin mRNA. Expression of mu-calpain protein was increased relative to control by DCAD+25-OH D3. The amount of 25-OH D3 and manipulated DCAD administered to cull native Korean cows was insufficient to improve tenderness of beef by increasing muscle Ca concentration. However, DCAD+25-OH D3 induced greater expressions of mu-calpain protein as well as mRNA.     

Dietary cation and anion difference: Effects on milk production and body fluid distribution in lactating dairy goats under tropical conditions

This study aimed to determine the effect of dietary cation and anion difference (DCAD) on milk production and body fluid distribution in lactating dairy goats. Ten dairy goats were selected and divided into two groups, five animals each. Animals received either control DCAD (control, 22.81 mEq/100 g dry matter (DM)) or high DCAD (DCAD, 39.08 mEq/100 g DM). The results indicated that rectal temperature (Tr), respiration rate, milk yield and compositions did not differ between groups. But the percentage change of Tr from the DCAD group was lower than the control group between 09.00 and 13.00 hours. DM intake tended to increase in the DCAD group. Dairy goats in the DCAD group drank more water, but urinary excretion and plasma antidiuretic hormone concentration remained unchanged. Apparent water balance was higher from the DCAD group over 24 h. There was no effect of DCAD on plasma and blood volumes, but tended to increase in extracellular fluid and thereby increased total body water. The present results indicate that animals supplemented with high DCAD increase their total body water and apparent water balance. These results have contributed to the process of adaptation for evaporative cooling and would be useful in slowing down the elevation in Tr.     

Effects of calcium intake and parity on plasma minerals and bone turnover around parturition

Eight pregnant heifers (primiparous cows) and seven pregnant cows in their second, third and forth pregnancies (multiparous cows) were assigned to two groups and fed either a low calcium (Ca) diet (Ca, 0.46%) or a high Ca diet (Ca, 0.86%) ad libitum from 3 weeks before the expected calving date to 3 days after parturition. All cows were examined for a change in dry matter intake (DMI), plasma minerals and bone turnover around parturition. The dietary Ca level did not affect the DMI in both primiparous and multiparous cows. The DMI of primiparous cows was significantly lower than that of multiparous cows (P < 0.05) in both the low and high dietary Ca groups. The dietary Ca level did not affect the concentrations of plasma Ca, phosphorus, magnesium and parathyroid hormone throughout the experimental period. Plasma phosphorus in primiparous cows was significantly higher (P < 0.05) than that of multiparous cows around parturition. Plasma Ca and magnesium tended to be higher (P < 0.10) in primiparous cows. The dietary Ca level did not affect the plasma osteocalcin (OC) level measured as bone formation or the urinary deoxypyridinoline (DPD) excretion measured as bone resorption before parturition in both primiparous and multiparous cows. After parturition, the plasma OC level was lower than it was before parturition in multiparous cows fed a low Ca diet, and in primiparous cows. There were no significant differences in urinary DPD excretion between each group before and after parturition. Both the plasma OC level and urinary DPD excretion of primiparous cows were significantly higher than those of multiparous cows in both the low and high dietary Ca groups.     

Influence of a vegetarian diet versus a diet with fishmeal on bone in growing pigs

This study was conducted to examine if substantial bone loss occurs in growing pigs fed a vegetarian diet in comparison with a diet containing fishmeal. Twelve 6-week-old weaned pigs were assigned to two groups: group V [vegetarian diet; 0.61% phosphorus (P) in dry matter until 25 kg and 0.46% P until the end of the experiment] and group F (fishmeal diet; 0.61% P in dry matter until 25 kg and 0.46% P until the end of the experiment). Phytase was added to both diets. These two diets were fed to the two groups for a period of 6 weeks. Blood samples were collected weekly, faeces were collected three times a week. Concentrations of osteocalcin (OC) and carboxyterminal telopeptide of type I collagen (ICTP) were measured in serum, using a radioimmunoassay, and bone-specific alkaline phosphatase (bAP) was measured using an enzyme immunoassay. Bone mineral density (BMD) and content (BMC) were determined by peripheral quantitative computer tomography (pQCT) in the tibia and phalanx. In addition, 1,25-dihydroxyvitamin D (VitD) and parathyroid hormone (PTH) were measured in serum. The digestibility of P was significantly decreased in group V. Significant changes in bAP activities and OC concentrations occurred with time during the 6 weeks. ICTP concentrations were significantly higher in group V. Total BMC and BMD in the tibia and BMD in the phalanx significantly decreased in group V. The results show that a vegetarian diet induces a significant loss of bone and a higher bone formation in group V compared with group F, although phytase was added to both diets. The dietary requirements for P in pigs, especially in the context of feeding vegetarian diets and adding an appropriate amount of phytase, should be investigated further.     

Preventive effect of mildly altering dietary cation-anion difference on milk fever in dairy cows

In the present study, we examined whether mildly altering dietary cation-anion difference (DCAD) contributes to the prevention of milk fever in dairy cows. Thirty multiparous cows and ten primiparous cows (heifer group) were used in this study and the multiparous cows were randomly divided into three groups of ten animals each (anion, non-anion and control groups). The cows in the anion group were given supplemental salts that slightly lowered DCAD. These salts consisted of 115 g of CaCO3, 42 g of CaHPO4, 65 g of MgSO4 x 7 H2O and 80 g of CaCl2 x 2 H2O as a daily dose for each cow, using a catheter from 21 days before the expected date of parturition until parturition. The cows in the non-anion group were given only the same Ca, Mg and ip supplement but no sulfate and chloride salts as that in the anion group. The cows in the control and heifer groups were not given any additional supplement. The incidence of hypocalcemia in the anion group decreased to approximately half of those in the non-anion and control groups, while the heifer group did not develop hypocalcemia at all. In addition, the number of days spent for the treatment of hypocalcemia and the number of drug bottles (calcium borogluconate solution) used for the treatment decreased to less than half in the anion group compared with those in the non-anion and control groups. At parturition, the serum Ca concentration in the control (6.2 +/- 1.9 mg/dl, mean +/- standard deviation) and non-anion groups (6.4 +/- 1.7 mg/dl) were significantly lower than that in the heifer group (8.3 +/- 0.4 mg/dl), and the level in the anion group was intermediate (7.3 +/- 1.3 mg/dl). The change in ionized Ca concentration was almost the same as that in serum Ca concentration, but only the concentration in the anion group tended to increase slightly from a week before parturition and was significantly higher than that in all other groups three days before parturition. Urinary pH in the anion group was maintained at a mildly acidic level (6.8-7.0) for the last two weeks before parturition, compared with those in the control (7.3-7.5) and non-anion groups (7.9-8.1), and similar to that in the heifer group (6.3-7.3). The urinary Ca excretion was the highest in the anion group among all groups during the prepartum period. There were no specific changes in the excretion of parathyroid hormone and 1,25-dihydroxyvitamin D in all groups of multiparous cows while the levels of these hormones remained low in the heifer group throughout the experimental period. The data in the present study indicates that the administration of anion salts that slightly lowered DCAD in the preparum period was effective for preventing milk fever in multiparous cows. Safe and mild metabolic acidosis induced by the anion salts could be evaluated by urinary pH (6.8-7.0), and might increase the responsiveness to Ca requirement at parturition through some complex mechanisms unrelated to the excretion of Ca-related hormones. In addition, it was clarified that primiparous cows have a high potential to respond to sudden Ca demand unrelated to hormone excretion, and their Ca metabolism was in some respects similar to that in multiparous cows fed anion salts. Therefore, manipulating mildly DCAD is expected to be an effective, safe and natural method for preventing milk fever in dairy cows.     

Influence of dietary phosphorus deficiency with or without addition of fumaric acid to a diet in pigs on bone parameters

The purpose of this study was to examine if substantial bone loss occurs in weaned pigs by feeding a phosphorus-deficient diet with or without fumaric acid. Eighteen weaned pigs were used. The animals were assigned to three groups: group C (control; 0.65% P on DM basis), group LP (low phosphorus; 0.37% P on DM basis) and group LPF (low phosphorus plus fumaric acid; 0.35% P on DM basis plus 2% fumaric acid). These three diets were fed to the groups for a period of four weeks after a two-week adaptation period. Blood samples were collected once a week. Carboxyterminal telopeptide of type I collagen (ICTP) in serum was used as a bone resorption marker. Osteocalcin (OC) and bone-specific alkaline phosphatase (bAP) were used as bone formation markers. Bone mineral density (BMD) and content (BMC) were determined by peripheral quantitative computer tomography. BAP activities significantly increased (24%) in group LPF, and at the last sampling day group LPF had significantly increased activities in comparison to group C. In contrast, ICTP concentrations significantly increased with time in group LP and LPF, and at the last sampling day group LPF had significantly increased activities in comparison to group C. BMD and BMC in femur and tibia significantly decreased in group LP and LPF. The results show that P-deficient diets induce a bone loss. Fumaric acid did not influence the degree of bone loss. With a better understanding of its effect on bone, dietary phosphorus requirements in pigs could be more precisely defined.     

Effect of diets containing sulfate or chloride-based anionic salts,fed to grazing prepartum dairy cows,on concentrations of Ca in plasma,disease incidence and milk yield

AIMS: To compare the effect of two partial mixed ration diets containing either sulfate or chloride-based anionic salts, fed to grazing prepartum dairy cows, on concentrations of Ca, Mg, P and beta-hydroxybutyrate (BHB) in plasma, disease incidence and milk yield during the early postpartum period.

METHODS: The study was conducted on a seasonal-calving grazing dairy farm located in Benton (MO, USA). In August 2016, two groups of 200 cows were randomly assigned at 30 days before expected parturition to receive either a sulfate or chloride-based anionic diet, to achieve a dietary cation–anion difference (DCAD) of ?25?mEq/kg DM. Cows were fed partial mixed rations to provide 50% of their DM intake, with 50% provided by grazing fescue pasture. Urine samples were collected from 20 cows from each group once a week for 5 weeks until calving for pH assessment. At parturition, 42 cows per group were selected at random and blood samples collected on Days 1, 2, 3 and 7 postpartum. The study continued until 100 cows per group calved. Health events and cumulative milk yield until 30 days postpartum were recorded. Concentrations of Ca, P, and Mg in plasma at Days 1, 2, 3, and 7, and BHB in plasma at Day 7 postpartum were assessed.

RESULTS: Mean urine pH was lower in cows in the chloride than sulfate group (p≤0.06) on four of five sampling occasions. Mean concentrations of Ca in plasma on Day 1 were 2.00 (95% CI=1.94–2.05) and 1.91 (95% CI=1.88–1.97) mmol/L for the chloride and sulfate groups, respectively (p=0.15), and on Day 3 were 2.03 (95% CI=1.97–2.08) and 1.90 (95% CI=1.84–1.96) mmol/L, respectively (p=0.038). Concentrations of Mg, P and BHB in plasma and incidence of diseases postpartum were similar in both groups (p>0.05). There were no cases of clinical hypocalcaemia in either group.

CONCLUSIONS AND CLINICAL RELEVANCE: Prepartum cows fed a partial mixed ration with a negative DCAD containing chloride-based anionic salts and free access to a fescue pasture had lower prepartum urine pH, and higher concentrations of total Ca in plasma during the first week postpartum, than cows receiving a partial mixed ration containing sulfate-based anionic salts.