Dietary Cation-anion Difference Research Articles

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.

Effects of dietary cation-anion difference on ruminal metabolism and blood acid-base regulation in dairy cows receiving 2 contrasting levels of concentrate in diets

Dietary cation-anion difference [DCAD=Na+K − Cl in mEq/kg of dry matter (DM)] increases DM intake (DMI) in cows fed diets containing rapidly degraded starch. Increased DMI of diets containing rapidly degraded starch could potentially exacerbate subacute acidosis. The objective of this study was to determine metabolic effects of increasing DCAD in low and high starch diets. Six cannulated Holstein cows were blocked into 2 groups of 3 cows and assigned to two 3 × 3 Latin squares in a split-plot design. Each group received a level of concentrate at either 20 or 40% on a DM basis. The diet containing 20% concentrate supplied 4% rapidly degraded starch, whereas the diet containing 40% concentrate supplied 22% rapidly degraded starch. Diets in each square were formulated to provide a DCAD of 0, 150, or 300 mEq/kg of DM. The 3 values were obtained by manipulating Na and Cl contents. Increasing the proportion of rapidly degraded starch decreased rumen pH and the acetate to propionate ratio but did not affect digestibility, blood acid-base status, pH of urine, and strong ion excretion. Increasing DCAD increased DMI, the effect being higher when the cows were fed the 40% concentrate diet. Increasing DCAD did not affect mean ruminal pH, molar proportion of VFA, and fiber digestibility; reduced the range of rumen pH decrease during the meal in cows fed the 40% concentrate diet; and strongly increased blood pH and blood HCO3 concentration. Increasing DCAD increased urine pH and modified the urinary excretion of minerals. With low DCAD, 70% of Cl and only 16% of Na were excreted in urine whereas with high DCAD, 33% of Cl and 53% of Na were excreted. These results suggest that DMI of cows fed diets rich in rapidly degraded starch and low DCAD was limited to maintain the blood pH in a physiological range. Increasing DCAD allowed the cows to increase DMI because of the ability of positive DCAD to maintain blood acid-base status. A localized rumen buffering effect could not be excluded and could be linked with a higher amount of HCO3 recycled into the rumen. Main mechanisms involved in regulating blood pH might be renal excretion of protons and strong ions and renal HCO3 reabsorption.

Anionic salts in the prepartum diet and addition of sodium bicarbonate to colostrum replacer, and their effects on immunoglobulin G absorption in the neonate

The objectives of this experiment were to determine whether feeding anionic salts to prepartum Holstein cows affected their calf's colostral IgG passive transfer and whether adding sodium bicarbonate to a colostrum replacer (CR) would increase the efficiency of IgG absorption. Forty Holstein cows and their resulting calves were assigned to a 2 × 2 factorial arrangement of treatments in a randomized complete block design based on expected date of calving. Three weeks before the projected due date, cows were placed on 1 of 2 treatments: a diet without anionic salts (dietary cation-anion difference of +77 mEq/kg) or a diet with anionic salts (dietary cation-anion difference of −100 mEq/kg). Within 45min after birth, all calves received 1 dose of a commercially available CR (132g of IgG) without or with supplemental sodium bicarbonate (19.5 g/dose). A half-dose of CR (66g of IgG) and sodium bicarbonate (9.75g) was fed at 6h of age. Calves received milk replacer at 12, 24, 36, and 48h. Blood samples were obtained from calves at 0, 6, 12, 24, and 48h and were analyzed for IgG concentration. Cows fed the diet supplemented with anionic salts had lower DMI on d 8, 5, 4, and 1 and lower urine pH 2 and 1 wk before parturition compared with cows fed the diet without supplemental anionic salts. Calves born from dams receiving anionic salts had similar IgG concentrations (15.1 vs. 14.4g/L) and apparent efficiency of absorption values (29.2 vs. 28.2%) compared with calves born from dams not fed anionic salts. Calves receiving supplemental sodium bicarbonate in the CR had higher serum IgG concentrations at 12 (14.4 vs. 12.0g/L), 24 (16.3 vs. 13.2g/L), and 48h (14.6 vs. 11.2g/L) and higher apparent efficiency of absorption values (31.2 vs. 26.1%) than calves that did not receive sodium bicarbonate in the CR. Calves receiving sodium bicarbonate also had greater area under the curve values for IgG absorption compared with calves not receiving sodium bicarbonate. There was a trend for an interaction with calves born from dams fed anionic salts having a greater area under the curve when fed supplemental sodium bicarbonate. Of the 40 calves in the study, 90% obtained adequate passive transfer (serum IgG ≥10g/L). This study indicates that feeding anionic salts to the dam has no effect on passive transfer, whereas adding sodium bicarbonate to the CR increased IgG uptake in calves.

Effects of increasing days of exposure to prepartum diets on the concentration of certain blood metabolites in dairy cows

To evaluate the effect of the number of days exposure to a prepartum transition diet on mineral, energy and protein metabolism in dairy cows. A prospective cohort study. The prepartum transition diet consisted of ryegrass pasture, cereal hay, grain, grain by-product, protein meals, BioChlor, rumen modifiers, minerals and vitamins and contained 13.9% crude protein, 10.0 MJ metabolisable energy/kg and a dietary cation anion difference of -35 meq/kg dry matter. Forty cows were bled bi-weekly from their introduction to the prepartum transition diet until day 35 of lactation. Blood samples were submitted for estimation of a range of metabolites. Cubic smoothed splines were fitted to scatterplots of metabolite concentration as a function of day relative to calving and the area under the curve (AUC) was calculated. Linear regression modelling determined the effect of days exposed, age, body condition score (BSC) and calving day on AUC. Results The prepartum AUC of blood phosphorus and beta-hydroxybutyrate increased and the AUC of blood calcium and cholesterol decreased with increasing days exposed to the diet. The postpartum AUC of beta-hydroxybutyrate and non-esterified fatty acids decreased with increasing days exposed but increased with days exposed x age and days exposed x BCS, respectively. The AUC of other metabolites did not vary significantly with number of days exposed. Conclusions Increasing exposure to the prepartum diet significantly altered the AUC of blood metabolites associated with mineral, energy and protein metabolism in ways consistent with improvements in production and reproduction previously reported and the result suggests links between energy, protein and skeletal metabolism.

Effects of increasing days of exposure to prepartum transition diets on reproduction and health in dairy cows

To evaluate the effect of the number of days exposure to a prepartum transition diet on reproduction and health in dairy cows. A prospective cohort study. We enrolled 1008 dairy cows from three herds to examine the effects on reproduction and health of increased days exposure to prepartum transition diets that included ryegrass pasture, ryegrass silage, cereal hay, grain, by-products, oilseed meals, BioChlor, rumen modifiers, minerals and vitamins. Diets provided 9.9 MJ metabolisable energy per kg dry matter (DM), a metabolisable protein balance of 286 g/day and a dietary cation anion difference of -150 meq/kg DM. Statistical models controlled for herd, calving day, age and gestation period. In two of the three herds increased days exposure to prepartum transition diets increased the hazards of submission for breeding, conception and clinical mastitis, and decreased the hazard of cow removal. The odds of pregnancy by 6 and 21 weeks after the mating start date tended to increase with increasing days of exposure to prepartum transition diets. Increasing exposure to a prepartum transition diet improved the calving to conception interval, tended to improve the odds of pregnancy and reduced the risk of culling of cattle, but increased the hazard of clinical mastitis.

Nutritional and management methods to decrease nitrogen losses from beef feedlots1

Nitrogen losses from open beef feedlots are a concern. Methods that decrease volatilization losses will lead to greater manure N, which is likely to be beneficial in open lot beef operations. Twelve or more pens were dedicated to N research whereby N intake, retention, and excretion were quantified and a mass balance conducted using manure, runoff, soil balance, and loss quantities. The objective was to decrease N volatilization losses or increase manure N or both. Dietary CP affects N excretion and N volatilization losses. Four experiments across 2 yr compared industry average CP (13%) to diets that were phase-fed to not exceed protein requirements (12.1 to 10.9%). Phase-fed cattle excreted 12 to 21% less N (P < 0.01), and N volatilization losses were reduced 15 to 33% (P < 0.01). In 2 other experiments, phase-fed diets were formulated to recycle undegradable intake protein. Steer G:F was similar (P = 0.18) or improved (P = 0.09), whereas N excretion and N volatilization losses tended to be reduced (P < 0.11) and N in manure was not affected (P > 0.35) compared with cattle fed 13% CP. Feeding less protein did not affect manure N, indicating manure N from open lots is related to other factors. A series of experiments evaluated increasing OM on the pen surface to increase N in manure. Feeding less digestible diets using fiber increased manure N (P < 0.01) and decreased (P < 0.10) N volatilization losses in 2 experiments conducted from November to May, but did not affect (P > 0.30) manure N or volatilization losses during 2 summer experiments. Adding bedding (i.e., OM) increased manure N in the winter as well. Another method evaluated was increasing pen cleaning frequency, which decreased N volatilization losses by 19 to 44% and increased manure N by 26 to 41% across 3 experiments. Other methods, such as acidifying manure by manipulating dietary cation anion difference, clinoptilite zeolite clay addition, and feeding different amounts of by-products had variable impacts on N volatilization losses. No treatments markedly affected runoff N, which is <5% of excreted N. Dietary protein affects N volatilization losses but not manure N. Other factors, such as OM on the pen surface, affect manure N. Cleaning manure frequently, which decreases exposure of manure N to air, decreases volatilization losses. Treatments should be evaluated across seasons due to seasonal effects.

Effect of different potassium levels in hay on acid–base status and mineral balance in periparturient dairy cows

Forages commonly used in dry cow rations contain high K concentrations. This results in a high dietary cation–anion difference (DCAD), which can compromise the calcium homeostasis of periparturient cows. The aim of this study was to determine the effect of 2 types of hay, fed during the prepartum period and differing in their K concentrations, on the peripartum acid–base status and mineral balance of dairy cows. During the prepartum period, the cows of group K33 (n=6) received a diet based on hay with a high K concentration (33g/kg of DM), whereas the cows of group K13 (n=6) received a diet based on hay with a low K concentration (13g/kg of DM). Both experimental diets were formulated to be isoenergetic and isonitrogenous. After calving, all cows received the same diet based on hay K33. Blood and urine samples were taken on d 14, 7, and 3 before parturition, at parturition, and then daily during the first 8 d after calving. Concentrations of minerals were analyzed in both blood and urine. Creatinine was also measured in urine for the calculation of the mineral:creatinine ratio. The acid–base parameters in blood (pH and HCO3− concentration) and urine (pH, net acid–base excretion, and base–acid quotient) were determined on d 14, 7, and 3 before parturition, at parturition, and on d 1 after parturition. The use of hay K13 reduced the DCAD value of the prepartum diet by half (195 vs. 514mEq/kg of DM). No significant differences between the 2 groups were observed for blood acid–base indicators or plasma minerals except for the Mg plasma concentration, which tended to be higher in group K13 from d 3 prepartum to d 2 after calving. In group K13, urinary Ca excretion tended to be higher from d 3 prepartum to d 1 after parturition than that in group K33. On d 3 before parturition, urinary pH and net acid–base excretion were significantly lower in group K13 than in group K33. On d 14, 7, and 3 before parturition, base–acid quotient was significantly lower in group K13 than in group K33. In group K13, daily feed intake and hence daily intake of Ca, P, and Mg during d 3 and 4 after parturition were higher than in group K33. The decrease of the DCAD in positive ranges by feeding a low-K hay before parturition induced a reduction of the metabolic alkalotic charge, as observed in acid–base parameters in urine, and increased the availability of Ca and P as a result of higher feed intake at the onset of lactation.

Effects of anion supplementation to low-potassium prepartum diets on macromineral status and performance of periparturient dairy cows

Data from multiparous Holstein cows (n=43) were used to determine whether supplementation of anions to low-potassium (K) prepartum diets would improve periparturient energy and macromineral status and affect performance during the postpartum period. Beginning 21 d before expected parturition, cows were fed a control diet (1.29% K; +10mEq/100g; n=21) or a low dietary cation-anion difference (DCAD) diet (1.29% K; −15mEq/100g; n=22) with anions provided through a combination of sulfate from calcium sulfate dihydrate (0.40% S total ration) and chloride (1.17% Cl total ration) from SoyChlor 16–7 (West Central, Ralston, IA). All cows were fed the same postpartum diet from parturition through 63 d postpartum. Feeding anions decreased overall urine pH (8.17 vs. 6.70) during the prepartum period. Overall, peripartum concentrations of plasma Ca, P, and Mg were similar between treatments; however, concentrations of plasma Ca tended to be increased during the first 24h postcalving in cows fed the low DCAD diet. Overall, concentrations of plasma P tended to be increased by feeding the anionic diet prepartum; this effect was more pronounced during the immediate peripartal period. Anionic supplementation did not affect incidence of clinical (<5mg/dL) and subclinical (5 to 8mg/dL) hypocalcemia, clinical hypophosphatemia (<2mg/dL), or clinical (<1.1mg/dL) and subclinical (1.1 to 1.8mg/dL) hypomagnesemia. Nevertheless, subclinical hypophosphatemia (2 to 4mg/dL) tended to be decreased at 16h postcalving and was decreased at d 2 postpartum for cows fed the anionic diet prepartum. Anion supplementation decreased prepartum dry matter intake (15.6 vs. 14.4kg/d), but did not affect postpartum dry matter intake (22.4 vs. 23.0kg/d), milk yield (46.5 vs. 46.1kg/d), or content and yield of milk fat and true protein. Plasma concentrations of energy-related metabolites (glucose, nonesterified fatty acids, β-hydroxybutyrate) were similar for both groups during the prepartum and postpartum periods. Glucose rate of appearance was determined by continuous infusion of 6,6-dideuterated glucose in a subset of cows between 6 and 10 d prepartum (control, n=12; low DCAD, n=9) and 7 and 10 d postpartum (control, n=9; low DCAD, n=8) periods. Glucose rate of appearance was not affected by treatment during the prepartum or postpartum periods. Overall, anion supplementation of low K diets improved P status during the early postpartum period, but did not affect aspects of energy metabolism or periparturient performance.

Effect of dietary cation-anion difference on measures of acid-base physiology and performance in beef cattle1

Dietary constituents can affect cow acid-base physiology and uterine pH. Dietary cation-anion difference (DCAD) has been shown to affect cow acid-base physiology, but the effect on uterine pH has not been demonstrated. The objective of this work was to determine if DCAD [(Na + K + 0.15Ca + 0.15Mg) - (Cl + 0.60S + 0.50P)] could affect cow DMI, acid-base physiology, and uterine pH, and second, to determine if dietary supplements could alleviate any negative effects of DCAD on these variables. In Exp. 1, 21 cows were utilized to determine the effect of a negative DCAD (-0.9 mEq/100 g of DM; low-DCAD) or positive DCAD (+25.0 mEq/100 g of DM; high-DCAD) diet on cow BW, DMI, and pH of blood, urine, and uterine flush fluid. In Exp. 2, 21 cows were randomly allotted to 1 of 3 treatments: control (-3.1 mEq/100 g of DM), molasses (+2.9 mEq/100 g of DM), or molasses+buffer (+25.8 mEq/100 g of DM) to determine if supplemental liquid molasses or liquid molasses with a buffer could alleviate the effects of a negative DCAD, forage-based diet. Cows were individually fed their respective diets for 42 d in both experiments. Cow BW, blood, urine, and uterine flush were collected on d 0, 21, and 42 during both experiments. Cow ADG was not different (P = 0.71) in Exp. 1 or Exp. 2 (P = 0.47). Hay DMI did not differ (P < 0.70) between high-DCAD and low-DCAD cows before d 28, but was greater (P < 0.001) for high-DCAD cows after d 28 in Exp. 1. In Exp. 2, mean hay DMI did not differ (P = 0.39) among treatments. In Exp. 1, a treatment x day interaction (P < 0.05) was apparent for blood, pH, base excess, bicarbonate, pCO(2), and urine pH. Blood gas and pH measures peaked on d 21 for high-DCAD and declined from d 0 to 42 in low-DCAD cows. High-DCAD cows had greater (P = 0.08) uterine flush pH compared with low-DCAD cows. In contrast, during Exp. 2 there were no differences (P > 0.14) among treatments for blood, pH, base excess, pCO(2), or uterine flush pH. Urine pH exhibited a treatment x day interaction (P < 0.0001). On d 21 molasses supplemented cow urine pH was greater (P < 0.0001) than control cows, whereas on d 42 molasses+buffer had greater (P = 0.01) urine pH compared with control and molasses cows. Dietary cation-anion difference and the use of molasses-based supplements had minimal effect on forage-fed beef cow DMI. However, DCAD has the capacity to alter forage-fed beef cow acid-base physiology and potentially affect uterine physiology.

Periparturient Effects of Feeding a Low Dietary Cation-Anion Difference Diet on the Metabolism of High-Producing Dairy Cows

Feeding rations with low dietary cation-anion difference (DCAD) to dairy cows during late gestation is a commonly used strategy in large herds to prevent periparturient hypocalcemia. Although the efficacy of low DCAD rations in reducing the incidence of clinical hypocalcemia is well documented, it is not clear whether the ensuing metabolic acidosis is associated with deleterious side effects during the transition period. The objective of the study presented here was to determine the effect of fully compensated metabolic acidosis on calcium and phosphorus homeostasis, insulin responsiveness, and insulin sensitivity as well as on indices for protein metabolism.

Predicting timothy mineral concentrations, dietary cation-anion difference, and grass tetany index by near-infrared reflectance spectroscopy

The mineral concentration of forage grasses plays a significant role in 2 metabolic disorders in dairy cattle production, namely, hypocalcemia (milk fever) and hypomagnesemia (grass tetany). Risks of occurrence of these 2 metabolic disorders can be evaluated by determining the dietary cation-anion difference (DCAD) and the grass tetany (GT) index of forages and specific rations. The objective of this study was to evaluate the feasibility of predicting timothy (Phleum pratense L.) mineral concentrations of Na, K, Ca, Mg, Cl, S, and P, the DCAD, and the GT index by near-infrared reflectance spectroscopy (NIRS). Timothy samples (n = 1,108) were scanned using NIRS and analyzed for the concentration of 7 mineral elements. Calculations of the DCAD were made using 3 different formulas, and the GT index was also calculated. Samples were divided into calibration (n = 240) and validation (n = 868) sets. The calibration, cross-validation, and prediction for mineral concentrations, the DCAD, and the GT index were performed using modified partial least squares regression. Concentrations of K, Ca, Mg, Cl, and P were successfully predicted with coefficients of determination of prediction RP2 of 0.69 to 0.92 and coefficients of variation of prediction (CVP) ranging from 6.6 to 11.4%. The prediction of Na and S concentrations failed, with respective Rp2 of 0.58 and 0.53 and CVP of 82.2 and 12.9%. The 3 calculated DCAD and the GT index were predicted successfully, with RP2 >0.90 and CVP <20%. Our results confirm the feasibility of using NIRS to predict K, Ca, Mg, and Cl concentrations, as well as the DCAD and the GT index, in timothy.

Effect of dietary ratio of Na:K on feed intake, milk production, and mineral metabolism in mid-lactation dairy cows

The objective of this study was to determine the effect of altering the dietary ratio of Na:K while keeping the dietary cation-anion difference (DCAD) constant, on dry matter (DM) intake, milk production, and mineral metabolism in lactating dairy cows. Fifteen mid-lactation Holstein cows averaging 160 d in milk were used in a replicated 3×3 Latin square design with treatments varying in the molar ratio of Na:K (0.21, 0.53, and 1.06). Diets contained A) 0.25% Na and 2.00% K, B) 0.50% Na and 1.60% K, or C) 0.75% Na and 1.20% K (on a DM basis), and all contained the same DCAD of 33mEq (Na + K – Cl – S)/100g of DM. There was a quadratic effect of the ratio of Na:K on DM intake (28.4, 27.5, and 28.3kg/d for diets A, B, and C, respectively). The ratio of Na:K did not affect milk yield (average 39.2kg/d), milk composition (average 3.60% fat; 3.01% protein; and 8.62% solids-not-fat), or coccygeal venous plasma concentrations of HCO3− (average 29.3mEq/L), Na+ (average 136.7mEq/L), K+ (average 4.53mEq/L), Cl− (average 97.5mEq/L), Ca (average 10.06mg/dL), and Mg (average 2.49mg/dL), and urinary pH (average 8.38) and ratio of Cl−:creatinine (average 4.35). The ratios of urinary Na+:creatinine (1.80, 4.21, and 7.42), Ca:creatinine (0.035, 0.041, and 0.064), and Mg:creatinine (0.53, 0.60, and 0.77) increased linearly with increasing ratios of Na:K, whereas the ratio of urinary K+:creatinine decreased linearly as the ratio of Na:K increased (22.4, 15.9, and 10.3). Milk production and composition of mid-lactation cows was similar among dietary ratios of Na:K with the same DCAD of 33mEq/100g of DM.

Timothy silage with low dietary cation-anion difference fed to nonlactating cows

Decreasing the dietary cation-anion difference (DCAD) by using anion sources before calving reduces hypocalcemia in cows at calving. Reduced DCAD from CaCl2-fertilized timothy hay achieves similar results, but the effects of feeding low-DCAD forage as silage have not been determined. The objective of this study was to evaluate the effect of low-DCAD timothy silage on dry cows. Six nonlactating and nonpregnant Holstein cows were used in a replicated 3 × 3 Latin square. Treatments were 1) control diet (DCAD=232mEq/kg of dry matter, DM); 2) low-DCAD diet using a low-DCAD timothy silage (LDTS; DCAD=−21mEq/kg of DM); and 3) low-DCAD diet using a fermentation by-product (LDBP; DCAD=−32mEq/kg of DM). Differences between dietary treatments were considered statistically significant at P≤0.05 and tendencies were noted when 0.05<P<0.10. Compared with the control, feeding LDTS tended to decrease DM intake (10.6 vs. 12.5 kg/d) and decreased urinary pH (6.15 vs. 8.18) as well as apparent digestibility of DM (67 vs. 69%). Blood pH (7.37 vs. 7.42), HCO3− (25.3 vs. 27.5mM), and base excess (0.4 vs. 3.1mM) were decreased, and blood Cl− (29.6 vs. 29.1mg/dL) was increased. Apparently absorbed Na and Cl were higher and apparently absorbed K, P, and digested ADF were lower for LDTS compared with the control. Both LDTS and LDBP resulted in similar DM intake. Urinary pH tended to be higher (6.15 vs. 5.98) and percentage of digested DM was lower (67 vs. 70%) with LDTS compared with LDBP. Blood ionized Ca (5.3 vs. 5.4mg/dL) tended to be lower and blood Cl− (29.6 vs. 30.1mg/dL) was lower, whereas blood pH (7.37 vs. 7.33), HCO3− (25.3 vs. 21.5mM), and base excess (0.4 vs. −3.8mM) were higher with LDTS compared with LDBP. Apparent absorption of Na, Cl, S, and P, as well as apparent digestion of acid detergent fiber, neutral detergent fiber, and N were lower, and K, Cl, S, P, Mg, and N were less retained with LDTS compared with LDBP. Results confirm that low-DCAD timothy silage can be used to produce a compensated metabolic acidosis by decreasing the DCAD of rations served to nonlactating dairy cows.

Effect of dietary cation-anion difference on urinary pH, feedlot performance, nitrogen mass balance, and manure pH in open feedlot pens1

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.

Timothy hays differing in dietary cation-anion difference affect the capability of dairy cows to maintain their calcium homeostasis

Forages low in dietary cation-anion difference (DCAD) can be used to decrease the DCAD in prepartum diet but the extent to which DCAD needs to be reduced is of recent interest. The objective of this study was to evaluate the effectiveness of timothy hays differing in DCAD at maintaining Ca homeostasis. Six nonlactating and nonpregnant multiparous Holstein cows were fed diets containing timothy (Phleum pratense L.) hay with DCAD values of 4.1±3.6 (LOW), 14.1±3.0 (MED), or 25.1±2.5 (HIGH) mEq per 100g of DM in a duplicated 3×3 Latin square design with 14-d experimental periods. The LOW and MED hays were produced by fertilizing established timothy fields at a rate of 224kg CaCl2 per ha, and HIGH hay was obtained from the same field where LOW hay was produced, but from a section not fertilized with CaCl2. Experimental diets, containing LOW, MED, or HIGH timothy hay at 71% of dietary DM, had DCAD values of 0.7, 7.3, and 14.4 mEq per 100g of DM, respectively. Animals were fed at 6% of metabolic body weight, which provided 108% of their daily energy requirement. For each period, after a 12 d diet adaptation, cows were subjected to an EDTA challenge (3 cows each on d 13 and 14). Infusion of EDTA solution into the jugular vein decreases the concentration of blood ionized Ca, and the EDTA challenge protocol determined the resistance time and recovery time: the time required for the blood ionized Ca concentration to decrease to 60%, and the time required to recover to 90% of the prechallenge concentrations, respectively. Urine pH was lower when cows were fed LOW compared with HIGH diet (6.88 vs. 7.83), but urine pH when cows were fed MED diet (7.15) did not differ from that when cows received the LOW or HIGH diet. However, immediately before the EDTA challenge, blood pH was lower when cows were fed LOW or MED compared with HIGH diet (7.44 vs. 7.47). Although the resistance time was not affected by treatments, the recovery time was shorter when cows were fed the LOW compared with MED or HIGH diet (185 vs. 248 and 263min, respectively). Blood pH decreased when cows were fed the LOW or MED diet, but the capability to maintain Ca homeostasis was enhanced only when cows received the LOW diet, in which the DCAD value was decreased to 1 mEq per 100g of DM.

Use of dietary cation anion difference for control of urolithiasis risk factors in goats

To determine correlations between dietary cation anion difference (DCAD) and urine pH, urine specific gravity, and blood pH in goats. 24 crossbred goat wethers. Goats were randomly assigned to 1 of 4 DCAD groups (-150, -75, 0, or +75 mEq/kg of feed) and fed pelleted feed and ground hay for 7 days. The diet was then supplemented with ammonium chloride to achieve the assigned DCAD of each group for 7 days. Urine was obtained for pH and specific gravity measurements at hours -3 to -1, 1 to 3, 5 to 7, 9 to 11, and 13 to 15 relative to the morning feeding. Blood pH was determined on alternate days of the study period. Goats in the -150 and -75 mEq/kg groups had a urine pH of 6.0 to 6.5 two days after initiation of administration of ammonium chloride, and urine pH decreased to < 6.0 by day 7. Goats in the 0 mEq/kg group had a urine pH from 6.0 to 6.5 on day 5, whereas urine pH in goats in the +75 mEq/kg group remained > 6.5 throughout the trial. Urine specific gravity differed only between the -150 mEq/kg and the -75 mEq/kg groups. Blood pH in the -150 mEq/kg group was significantly lower than that in the other groups. Goats in the 0 mEq/kg DCAD group had a urine pH of 6.0 to 6.5 five days after intitiation of feeding the diet, and that pH was maintained through day 7, without significant reduction in blood pH. This may serve as a target for diet formulation for the prevention of urolithiasis.

Effects of acidified fermentation by-productsand prepartum DCAD on feed intake, performance, and health of transition dairy cows (2009)

Two commercially available acidified fermentation by-products were evaluated in the close-up period (21 days before expected calving) for their effects on feed intake, postpartum performance, and cow health. Diets were formulated to contain similar protein and energy values but differed in dietary cation anion difference and anion source. Treatments were Bio-Chlor, SoyChlor, and a control. Prepartum feed intake tended to be lower for SoyChlor than for the control, but postpartum intake did not differ among dietary treatment groups. Likewise, no significant differences were detected for milk yield between treatments. Protein percentage, milk urea nitrogen, and lactose percentage were greatest for SoyChlor-treated cows. Therefore, despite a trend for a negative effect on prepartum feed intake, SoyChlor supported similar productivity in early lactation.

Altering physiological conditions and semen acidity by manipulating dietary cation-anion difference and fish oil supplemenation of Garut breed rams

Contribution of Garut breed sheep as protein resources is not optimal yet. Acceleration of population growth such as increasing of female offspring is neccesary. This study was carried out to obtain information regarding the effect of dietary cation-anion difference (PKAR: meq [(Na + K) – (Cl+S)/100 g of dry matter]) and fish oil supplementation on acidity of blood and semen, blood gas and plasma and semen mineral. The dietary treatmens were as follows: RN0= basal ration (PKAR +14) without fish oil, RNI= basal ration (PKAR +14) with 3% fish oil, RB0= base ration (PKAR +40) without fish oil, RBI= base ration (PKAR +40) with 3% fish oil, RA0= acid ration (PKAR -40) without fish oil, and RAI= acid ration (PKAR -40) with 3% fish oil. The rations contained 150 ppm of zinc and were offered to 18 of Garut rams. The result indicated that blood pH, pCO 2 , and pO 2 were not affected by PKAR and fish oil supplementation, but cHCO 3 and cBase were affected (P<0.05). PKAR and fish oil supplementation affected (P<0.01) plasma Mg and S, but did not affect K, Na, Zn and Cl. Semen pH after day 28 of experimental period were highly significant different and that followed PKAR pattern. In conclution, PKAR affected cBase, cHCO 3 , concentration of Mg and S plasma and semen pH of Garut rams. The result suggested that PKAR could be applied to manipulate physiological condition and semen pH. Key Words : PKAR, Physiological Condition, Semen, Garut Ram

Use of dietary cation anion difference for control of urolithiasis risk factors in goats

Use of dietary cation anion difference for control of urolithiasis risk factors in goats

Clinical considerations and regulation of acid-base balance in cattle

SUMMARY Understanding the electrolyte and acid-base disorder depends on the comprehension of the physiological mechanisms which regulates them, and the interpretation of changes in blood pH. Some diseases produce a constant pattern of electrolyte and fluid loss with foreseeable changes in electrolyte concentration and fluid volume. Furthermore, one or more of the regulatory components may become compromised, resulting in disorders of the acid-base status. Currently there are three approaches to the clinical assessment of acid-base status: the Henderson-Hasselbach equation, the strong ion model and the simplified strong ion model, dependent its use on considerations of the professional. The manipulation of the dietary cation-anion difference (DCAD) is defined as the m-equivalents of (Na + K) - (Cl+S) by kilogram (mEq/kg) of dry matter (DM) It has a direct effect on the acid-base status, being ammonium chloride the most acidifying salt and magnesium sulfate the most palatable anionic salt, taking in count that urinary pH is a useful tool to assess the degree of metabolic acidosis imposed by the anionic salts. Laboratory values are just one step in an electrolyte and acid-base analysis of patient. To make rational decisions these values must be correlated with the clinical picture and the knowledge of the underlying biochemistry and physiology, using the important principles of evidence-based medicine.