A short introduction to the new principle of binding ration calcium with sodium zeolite.

This paper summarise the development of the new principle of preventing parturient hypocalcaemia by reducing the bioavailability of ration calcium with calcium binders, based on the idea that a negative calcium balance would stimulate natural defence mechanisms against threatening hypocalcaemia. Synthetic sodium zeolite was selected as a first choice among the many calcium binders available commercially, such as polyphosphates, citrate, EDTA and it derivatives. Testing was done on non-pregnant rumen fistulated cows in the first place, followed by cows in late lactation. Encouraged by the tendencies seen in these animals, the final proof of concept was done on pregnant dry cows fed a supplement of synthetic sodium zeolite A from 4 weeks before expected calving until calving. By analysis of blood calcium levels, this supplementation was shown to have a stabilizing effect during the critical period shortly after calving.

The effect of zeolite A supplementation in the dry period on blood mineral status around calving.

This article summarizes the results obtained in 6 separate studies concerned with the effect of zeolite A supplementation in the dry period on blood calcium, magnesium and phosphorus status around calving. The experiments were conducted on 5 different farms, and comprised a total of 117 cows. Two of the experiments (exp. 5 and 6) were conducted under extensive farming conditions whereas the rest (exp. 1-4) were conducted on intensively driven farms. All cows included in the experiments had completed at least 2 lactations. The cows were allocated as either untreated control cows or zeolite treated experimental cows according to expected date of calving and parity. The experimental cows were fed between 0.5 and 1.0 kg of zeolite A per day during the last 2 to 4 weeks of the dry period. Blood samples were drawn on the day of calving and day one and two after calving (all experiments), three weeks before the expected date of calving (exp. 1 and 2) and one week after calving (exp. 3 and 4). The zeolite supplementation significantly increased the mean serum Ca level on the day of calving. The efficiency of the zeolite supplementation to prevent hypocalcaemia (serum Ca < 2.00 mmol/l) on the day of calving was calculated. Efficiencies varied ranging from 3 to 100%, with a mean efficiency of 58%. The zeolite-calcium ratio (g of zeolite per cow per day/g of dietary calcium per cow per day) was calculated in each experiment. From the results it seemed, that zeolite-calcium ratios below 5 did not effectively prevent parturient hypocalcaemia, whereas ratios of 10 to 20 proved very efficient in preventing hypocalcaemia. There was apparently no additional effect from feeding zeolite for 4 instead of 2 weeks prepartum. Feeding zeolite in the dry period significantly decreased plasma phosphate before as well as after calving. The phosphate level was normalized within one week after calving. Plasma magnesium was significantly lower among the experimental cows on the day of calving, but stayed within the normal range of plasma magnesium. The control cows on the other hand experienced hypermagnesemia after calving.

Aspects of physiological effects of sodium zeolite A supplementation in dry, non-pregnant dairy cows fed grass silage.

The objective of the present study was to monitor serum and urine biochemical changes in dairy cows during and after oral administration of a synthetic sodium aluminium-silicate (zeolite A). A prospective longitudinal study involving four non-pregnant and non-lactating cows was chosen. Cows were randomly allocated to either a control or experimental group. The period of observation was three weeks. During the first week (period 1) cows were maintained on basic ration for the purpose of recording baseline values. During the second week (period 2) control cows were fed a basic diet (grass silage), while cows in the experimental group were fed the basic diet and supplemented with 1 kg zeolite pellets once daily. During the third week (period 3) both groups were fed the basic ration only and observed for any persistent effects after zeolite withdraw. Daily sampling included blood and urine. Selected physiological parameters were compared between groups during period 2 and 3, whereas mean values from period 1, 2 and 3 were compared within the groups. Zeolite supplementation revealed a significant influence on calcium homeostasis. A slight decrease in serum Ca and in renal excretion of calcium was observed in the experimental group at initiation of supplementation, whereas an increment in these parameters was recorded after withdrawal of zeolite supplementation. It is assumed, that zeolite caused a reduction in the availability of dietary calcium during supplementation, which possibly elicited an activation of calcium mobilisation. The influence of zeolite on calcium homeostasis was not evident from monitoring serum concentration of calcium regulating hormones (PTH, 1,25(OH)2D3, 25(OH)VitD) or renal excretion of markers of bone resorption. Enhanced active intestinal calcium absorption and bone resorption was therefore considered insignificant in the calcium mobilisation under the conditions of this experiment. The origin of the increased amount of Ca, which was observed in serum and urine after zeolite withdraw, is at present unknown, but it is suggested, that the readily mobilized Ca-pool in bone was a contributing factor. An effect of zeolite on phosphate and magnesium homeostasis in the experimental group was evidenced from the values of serum concentration and fractional excretion, which during supplementation were significant lower than in the control group. The influence of zeolite on phosphorus and magnesium is presumed to result from a combination of interference of zeolite with intestinal absorption and a marginal dietary supplementation of these minerals.

The effect of zeolite A supplementation in the dry period on periparturient calcium, phosphorus, and magnesium homeostasis.

One potential way of preventing parturient hypocalcemia in the dairy cow is to feed dry cow rations very low in calcium (<20 g/d); but, because it is difficult to formulate rations sufficiently low in calcium, this principle has been almost abandoned. Recent studies have shown, however, that it is possible to prevent milk fever, as well as subclinical hypocalcemia, by supplementing the dry cow ration with sodium aluminium silicate (zeolite A), which has the capacity to bind calcium. The aim of this study was to further evaluate the effect, if any, of such supplementation on other blood constituents, feed intake, and milk production in the subsequent lactation. A total of 31 pregnant dry cows about to enter their third or later lactation were assigned as experimental or control cows according to parity and expected date of calving. The experimental cows received 1.4 kg of zeolite pellets per d (0.7 kg of pure zeolite A) for the last 2 wk of pregnancy. Blood samples were drawn from all cows 1 wk before the expected date of calving, at calving, at d 1 and 2 after calving, and 1 wk after calving. Additionally, a urine sample was drawn 1 wk before the expected date of calving. Zeolite supplementation significantly increased the plasma calcium level on the day of calving, whereas plasma magnesium as well as inorganic phosphate was suppressed. Serum 1,25(OH)2D was significantly increased 1 wk before the expected date of calving among the experimental cows, whereas there was no difference in the urinary excretion of the bone metabolite deoxypyridinoline between the two groups. Feed intake was decreased among the zeolite-treated cows during the last 2 wk of pregnancy. No effect was observed on milk yield, milk fat, and milk protein in the subsequent lactation. The mechanisms and interactions involved in zeolite supplementation are discussed in relation to the observed improvement in parturient calcium homeostasis and to the observed depression in blood magnesium and inorganic phosphate.

Milk fever control principles: a review.

Three main preventive principles against milk fever were evaluated in this literature review, and the efficacy of each principle was estimated from the results of controlled investigations. Oral calcium drenching around calving apparently has a mean efficacy of 50%-60% in terms of milk fever prevention as well as prevention of milk fever relapse after intravenous treatment with calcium solutions. However, some drenches have been shown to cause lesions in the forestomacs. When using the DCAD (dietary cation-anion difference) principle, feeding rations with a negative DCAD (measured as (Na + K)-(Cl + S)) significantly reduce the milk fever incidence. Calculating the relative risk (RR) of developing milk fever from controlled experiments results in a mean RR between 0.19 and 0.35 when rations with a negative versus positive DCAD are compared. The main drawback from the DCAD principle is a palatability problem. The principle of feeding rations low in calcium is highly efficient in milk fever prevention provided the calcium intake in the dry period is kept below 20 g per day. Calculating the relative risk (RR) of developing milk fever from controlled experiments results in a very low mean RR (between 0 and 0.20) (daily calcium intake below versus above 20 g/d). The main problem in implementing the low-Ca principle is difficulties in formulating rations sufficiently low in calcium when using commonly available feeds. The use of large doses of vitamin D metabolites and analogues for milk fever prevention is controversial. Due to toxicity problems and an almost total lack of recent studies on the subject this principle is not described in detail. A few management related issues were discussed briefly, and the following conclusions were made: It is important to supply the periparturient cow with sufficient magnesium to fulfil its needs, and to prevent the dry cows from being too fat. Available information on the influence of carbohydrate intake, and on the effect of the length of the dry period and prepartum milking, is at present insufficient to include these factors in control programmes.

Serum calcium response following oral zinc oxide administrations in dairy cows.

Six non-pregnant cows were allocated into 3 groups. Group 1 comprised a pair of lactating cows, whereas groups 2 and 3 each comprised a pair of non-lactating cows. The cows in groups 1 and 2 were dosed intraruminally by stomach tube with zinc oxide at 120 mg Zn per kg of bodyweight at weekly intervals for a period of 33 days. Each cow received a total of 4 doses of zinc oxide. Group 3 served as non-treated control group. Blood samples were collected from all 6 cows daily. Serum was analysed for concentration of calcium. Within 12-24 h of each zinc oxide administration the serum calcium of the lactating cows dropped dramatically indicating the existence of an antagonistic effect between Zn and Ca. The first Zn induced hypocalcaemic episode in the lactating cows was followed by a rise in serum calcium to a level above the pre-dosing level and above the mean value of the control group. The depth of the hypocalcaemic response decreased with the number of zinc oxide dosings. This effect was explained as a response from the stimulation of the calcium homeostatic mechanisms. In the Zn dosed non-lactating cows responses were similar but less clear. The perspective of these findings is discussed in relation to resistance towards parturient hypocalcaemia.

Milk fever and subclinical hypocalcaemia--an evaluation of parameters on incidence risk, diagnosis, risk factors and biological effects as input for a decision support system for disease control.

The present review analyses the documentation on incidence, diagnosis, risk factors and effects of milk fever and subclinical hypocalcaemia. It is hereby evaluated whether the existing documentation seems sufficient for further modelling in a decision support system for selection of a control strategy. Several studies have been carried out revealing an incidence of milk fever most often in the level of 5-10%. Few studies indicate that the incidence of subclinical hypocalcaemia is several times higher than milk fever. The diagnosis based on clinical or laboratory methods or based on presence of risk factors is outlined. The clinical symptoms of milk fever are highly specific and the disease level may thus be determined from recording of treatments. Diagnosis of subclinical hypocalcaemia needs to include laboratory examinations or it may be determined by multiplying the incidence of milk fever by a certain factor. From the documentation on risk factors, it is very complex to predict the incidence from the exposure level of the risk factors. Due to uncertainty, sensitivity analyses over a wide range of values for each parameter are needed. The documentation of cow characteristics, nutrition, environment and management as risk factors are described. Among cow characteristics, parity or age, body condition and production level were found to be important. Risk factors associated with nutrition included most importantly dietary cation-anion difference and calcium level whereas the importance of general feeding related factors like type of feed stuff and feeding level were less clear. Environment and management included season, climate, housing, pasturing, exercise, length of dry period and prepartum milking. Several of the parameters on environment and management were confounded among each other and therefore firm conclusions on the importance were difficult. The documentation of the effect of milk fever includes the downer cows, reproductive disorders, occurrence of other diseases and the effect on milk production, body weight and culling. The reproductive disorders included most importantly dystocia, uterine prolapse, retained placenta, metritis and repeat breeding, and occurrence of other diseases included ketosis, displaced abomasum and mastitis. The documentation was substantial and often quantifiable within certain limits. Overall it is concluded that the present documentation on milk fever concerning incidence, diagnosis, risk factors and effects seems sufficient for a systematic inclusion in a decision support system. A model on milk fever should take into consideration the variation in biological data and individual herd characteristics. The inclusion of subclinical hypocalcaemia would be more uncertain and probably should await further documentation on possibilities of determining the herd level incidence and also the effect of this condition on production.

Effect of oral drenching with zinc oxide or synthetic zeolite A on total blood calcium in dairy cows.

Danish Holstein dairy cows in late lactation and milked in the morning only were used as a model for dry pregnant cows to determine the effect of oral drenching with zeolite A and zinc oxide, respectively, on total serum calcium. Ten cows were assigned randomly to two groups of five cows each, given either synthetic zeolite A (group A) or zinc oxide (group B). Blood samples were drawn daily at 10 a.m. and 10 p.m. during the whole experiment, and total serum calcium was determined. Daily fluctuations in blood calcium were recorded, with morning values being consistently lower than evening values. Oral drenching with a single dose of zinc oxide of 100 mg/kg of body weight as well as with zeolite in doses of 500 g of zeolite/cow twice a day for 2.5 d was reflected in serum calcium levels. In the group given zeolite A, there was a depression in evening values of total serum calcium although the difference did not reach statistical significance. It was followed by an increase above baseline level ("overshooting"). This was interpreted as a response from the calcium homeostatic mechanisms. In the group given a single dose of zinc oxide, a decrease in total serum calcium occurred. This decrease was not followed by overshooting, indicating that the single treatment with zinc oxide did not stimulate the calcium homeostatic mechanisms. The perspective of this first attempt to reduce dry cow ration calcium availability may be seen in relation to difficulties in formulating dry cows rations from home grown forage sufficiently low in calcium to elicit a hypocalcemia protective response at calving.

Hot topic: prevention of parturient paresis and subclinical hypocalcemia in dairy cows by zeolite A administration in the dry period.

To test the effects of a zeolite feed supplement on parturient calcium status and milk fever, two groups of dry cows were treated with either 1 kg of zeolite/d or none for 4 wk prepartum. At calving and d 1 and 2 after calving all cows were given 250 g of calcium carbonate as a drench, and a blood sample was taken. Serum calcium analysis revealed a greater calcium concentration in zeolite-treated cows. While three control cows contracted milk fever, necessitating intravenous calcium therapy, and six out of eight control cows experienced serum calcium levels below 2 mmol/L in one or more samples taken, none of the zeolite-treated cows contracted milk fever or experienced subclinical hypocalcemia.