Racz, V.

Stewart, J.W.B.

English

eCommons@USASK

Copper and molybdenum status of pastures in eastern Saskatchewan

University of Saskatchewan Research Archive

- 110 -COPPER AND MOLYBDENUM STATUS OF PASTURES IN EASTERN SASKATCHEWAN J.W.B. Stewart Department of Soil Science, University of Saskatchewan Saskatoon, Sask. and V. Rac:z; Saskatchewan Department of Agriculture Regional Extension Services Branch Yorkton, Sask. Introduction In the last few years there has been an increasing demand from livestock producers, veterina~ians, and SDA agricultural representatives for information on the copper status df pastures and soils in eastern Saskatchewan. Evidence ha~ accumulated (Brockman, 1976) of casBs wher~ copper deficiency diagnosed in animals on the basis of hair color, bloch copper levels and occasionally liver copper levels, has been confirmed by growth response to dietary copper supplementation. Brockman (1977) also collected 100 liver samples at random from animals slaughtered by local farmers and by Intercontinental Packers in Saskatoon and found 60% of the liver samples to be 10 ug/g D.M. or less. This suggests that copper deficiency may be a greater problem in Saskatchewan than we presently know. Copper deficiency expresses itself in the· animal in a variety of deficiency symptoms. These have been described (Christensen and Cbohran, 1975) as loss of appetite in general but with a craving for salt, rough hair coat, reproductive failure and low hemoglobin. Copper deficiency was first observed in cattle in 1931 and since then many studies have been carried out. For instance, in 1952 Marsden quoted 828 references and gave levels of deficient blood copper (below 1 ug of Cu/ml) and liver copper (normal values ab6ve 100 ug/g D.M. with recorded values as low as 5 ug/g). In the same review it was noted that copper levels could be adequate in forage, but that copper deficiency symptoms could occur in the animal because of the high intake of molybdenum. Interest in molybdenum had already been 'stimulated by observations that cattle on so-called "teart" pastures were found to scour persistently and profusely owing to high molybdenum.levels in the pasture. Research on molybdenum in animal nutrition has been focussed primarily on its interactions with copper and sulphate, particularly in ruminant nutrition. At least four significant interactions occur in the gas-t:rointestional tract or in the tissues - 111 -(Nicholas and Egar, 1974):-1. Interaction of molybdate and sulphate in the reduction of sulphate to suiphide by ruminai microorganisms. 2. Formation of copper sulphide in the gastrointestional tract, decreasing copper availability. 3. Interaction of molybdate with transport of copper across membranes, and 4. Interaction of sulphate on absorption, transport and excretion ·Of molybdate. A variety of factors other than dietary copper, molyb-denum and sulphur interrelationships have been suggested (Christensen and Cochran, 1975) as factors in the incidence and severity of Cu deficiency. Dried forage was found to permit greate~retention of liver copper than the same forage consumed fr~sh. Toxic levels of cadmium increased liver copper concentrations, manganese levels in forage of cattle also may be important. Copper Levels in Forage Work in. Canada on the occurrence of copper deficiency (Henderson, 195 7; Mil tmore et aL , 19·64, 1971, 1973) confirms the existence of "conditioned copper deficiency" which Henderson attributed to the hi~h molybdenum intake rather than an uncomplicat~d copper deficiency. Henderson (1957) described the deficiency as occurring in the Swan River area of Manitoba, mainly in summer months, especially in a year of high rainfal1 ~n cattle grazing lush pasture. Later work on soil parent material (Fletcher and Doyle, 1971) in West Central Manit6ba reported a few small area of abnormally high molybdenum values related to weathering shales but found that the shale~ were usually marked by variable thickness of glacial drift material. Plant Mo levels were not related to total soil Mo levels. Miltmore's studies (1964, 1971, 1973) looked at copper, molybdenum and sulphate contents of forage and suggested that ratios of copper to molybdenum of 2:1 and higher were considered safe but al1 feeds having ratios of 1,9:1 and lower were dangerous, Grass, sedge and oat forages tended to have lower ratios than legumes, corn silage, or cereal grains. As far as suphur content of forage were concerned, syouring occurred in cattle when forage sulphur was high (0.65%), but was found to be lower (0.26%) where scouring did not occur. Current United States NRC (1971) beef and dairy cattle requirements for copper are in general agreement with these findings as "copper to molybdenum rati·os in feeds may be of more importance than actual copper levels. Ratios of 1:1 or - 112 -2:1 may lead to copper deficiency, particularly at high (over 0.3% of sulphur in dry matter), Cu/Mo ratios of 4:1 and higher should not cause any problems," Clark and Drysdale (1974) made a study of forage in the northwest region of Manitoba and suggested that the require-ments for cattle from the copperrmolybdenum standpoint are lO•ppm copper when molybdenum content is 1 p~m or less. When molybdenum is greater than 1 ppm the copper~molybdenum ratio should be at least 3:1 with a ratio of 4~1 preferred. In their survey of 66 locations, only 10 samples were found to be sufficient in copper for cattle production. Copper Levels in Soils Stewart (19B9) carried out a survey of the levels of available soil copper in Saskatchewan soils and related it to production of cereal grains. This study showed that the level of copper in the soils was not limiting cereal yield and that there was a good correlation betwe~n the amount of copper extracted by a chelate such as EDTA or DTPA and the concentrations in the plant material. Plant copper concen-tration of 5 ug/g D.M. and greater was thought to be sufficient for normal plant growth. Later work by Heil and Follet (1972) is in agreement with this finding and that 0.2 ug/g DTPA extractable Cu or.more in the soil would be sufficient for plant growth. Available sulphate levels in soil are currently run on all soil samples submitted to the Soil Testing Laboratory and information is available on the sulphur status of soils in many areas of Saskatchewan. Some information is also available on plant sulphate levels. A few studies have been reported in the literature on the interaction of Cu X S X Mo in soils· and the effect of this interaction on forage composition (Gupta and McLeod, 1975). Preliminary Survey Program A joint survey program was carried out in 1976 during which cattle hair, blood and where possible liver samples were analyzed fvom specific herds where Cu deficiency had been diagnosed and soil-plant-water samples were collected from the pastures grazed by the same cattle. Results on the cattle hair, blo~d and liver samples are recorded elsewhere (Brockman, 1976, 1977) and this report will deal with the results obtained to date from soil and plant analyses. Material and Methods Thirty-two :Plastures (locations shown on Fig. 1) were sampled in May 1976. Soil samples were taken in 15 em inter-vals to 120 em (48 11 ) depth in May; plant samples were taken at monthly intervals until September. R.l8 Fig • 1 LOCATION OF SAMPLE SITES N!. 1-27. MAP SYMBOLS TAKEN FROM SOIL SURVEY REPORT NLI2. R.6 1-' 1-' w I - 114 -Soil Analyses In addition to pH, texture~ electrical conductivity, av~ilable N, P, K and S analyses carried out by the Soil Testing Laboratory, DTPA extractable Cu and Zn (Lindsay and Norvell, 19£9), 1 N ammonium acetate extractable Band 1 M ammonium carbonate extractable Mo values were obtained. The ammonium carbonate test developed by Vleck and Lindsay (1976) is as follows:- Shake 25 g soil with 50 ml 1M (NH4)2C03 (pH 9) for 12 hours on a rotary shaker. Centrifuge and filter. Analyze calorimetrically by the thiocyanate procedure after H202-H2S04 digeBtion to remove organic matter. The critical level for alfalfa toxicity is approximately 1.7 ppm. Plant AnalyBes Boron, zinc, copper, molybdenum and sulphur analyses were car~ied out on the plant material us{ng acid digestion of the plant material and element deter~ination by colori-metric (boron, m~lybdenum and sulphur). methods utilizing a T~chnicon system and atomic absorption spectrophotometry (copper and zinc). Water Analyses Wate~ samples were collected at each location from the main s6urce of water supply for the animals (dugout, well~ slough, creek). These samples were analyzed for electrical conductivity, B, Mo, Cu~ Zn and S04-S content. Results Soil Analyses The soil pH values ranged from 7.0 to 8.7 and salinity was determined by electrical conductivity in~reasing markedly in some lower soil depths and rea6hing extremely high values in the vicinity of Quill Lake. N03-N and HC03-P were low in all,soils except where fertilizer had been applied. Potassium was in sufficient supply at all locations. Extractable sulphate was generally high >96 kg/ha in the top 60 em except for very sandy soils in the vicinity of Theodore, Springside and Otthon. At Theodore a good yield response was obtained by other workers to sulphate fertilization of the same grassland site. The extractable micronutrient fluctuated widely from site to site. For instance, DTPA Cu values ranged from 0.16 ug/g to 1.48 ug/g in the 0-15 em soil depth. Heil and Pollet (1972) suggest that any soil with leEs than 0.2 ug/g DTPA extractabl~ Cu would not contain enough Cu for plant growth. Two top soils tested lower than this value and it could be argued that for a plant concentration of 10 ug/g the soil lev~l should be higher. Extractable Mo levels - 115 -varied from 0.10 to 0.61 in the top 0-15 em soil depth. Lower depth in the soil (90-120 em) tende4 to have more extractable Mo (range 0,05-0.77) but no consistent trend was observed nor did the level of extractable Mo reach levels known to produce toxic alfalfa >1.7 (Vleck, 1976). DTPA extracta~le zinc levels ranged from 0.36 to 5.40 ug/g in the top 0-1~ em. Lindsay and Norvell (1969) found that soils with extractable zinc levels of less than 0.5 were low in availab1e zinc. Using this criteria (which was developed using maize as a test crop) four sites could be deficient in zinc. Plant Analyses Plant samples taken at each site in May, June, July, August and September were analyzed for total zinc, copper~ molybdenum and sulphur. Table 1 presents a summary of the Table 1. Mineral levels according to time sampled and type of forage (Yorkton forage samples , 1976). Cu Mo Ratio Cu:Mo Group I (Definite Problems) Ave. of total ' sample (14) 14.5 2. 3 6. 3 Ave. of cult. grass samples ( 9) 15.3 2. 4 6. 3 Ave. of native grass samples (2) 16.7 0. 7 23.8 Ave. of ·total sample: May (14) 11.1 1.9 5 . 8 Ave. of cult. grass samples: 12.3 2.1 5. 8 May ( 9) Ave. of native grass samples: 10.0 0. 5 20 May ( 2) Ave. of to.t.al sample: July (14) 14.3 2.4 6. 0 Ave. of cult. grass samples: 14.3 2. 5 6 .1 July ( 9 ) Ave. of native grass samples: 17.3 0.4 43.3 July ( 2 ) Group II (Possible Problems) Ave. of total sample* (16) 15.3 1.8 8. 5 Ave. of cult. grass·samples (10) 13.9 1.7 8. 2 Ave. of native grass samples ( 5) 17.8 1.3 13.7 Ave. of total sample: May (16) 11.2 1.2 9. 3 Ave. of cult. g.rass samples: 12.0 1.2 10 May (10) Ave. of native grass samples: 9. 7 0. 7 13.9 May ( 5) Ave. of total sample: July (16) 16.4 2. 0 8. 2 Ave. of cult. grass samples: 14.2 1.9 7. 5 July (10) Ave. of native grass samples: 19.3 1.3 14.9 July (5) - 116 -Ta]i>ie 1. Can't Group III (No Ave. of total sample* ( 2) Ave. of May sam~les (2) Ave. of J'Uly sam:ples (2) * Cu Problems) 24.0 12.3 31,2 Mo 1.1 0. 8 1.4 Ratio Cu:Mo 21.8 15.4 2 2. 3 Samples from each field in May, June, Jtily, August and September, ( ) Denotes number of samples in each group. 'i. copper and molybdenum data from all sites and compares the Cu:Mo ratios of forage from sites where copper deficiency had been diagno~ed versus sites where ~opper deficiency was a possibility but not proven, Copper-molybdenum ratios were lower in the samples with definite Cu problems than in those with possible problems. Molybdenum uptake was greater with tame species (refle~ting the greater 'Uptake of Mo by alfalfa) than native species. Copper values were lower in the May samples than on later sampling dates. (Note - This may reflect the fact that dietary copper supplementation was practised by some herds). · A more detailed look at this data (Table 2) shows Cu and Table 2. Forage copper and molybdenum samples taken from Maydel Farms, Theodore (sandy soils). pH DTPA Cu Ext. Mo E.C. ~~ } May Cu:Mo ~~ } July Cu:Mo Cu } Mo Sept. Cu:Mo Site 1 6. 7 0.32 0,42 0. 5 19.2 1.6 12.3 13.0 0. 7 15.8 10.8 2.1 5. 3 Site 2 6.9 0.34 0,40 0.2 8.1 1.0 8.0 13.1 1.8 7.1 14.8 1.9 7. 8 Site 3 7.5 0.62 0.26 0.4 9. 6 2.1 4.7 9.7 1.5 6.4 11.4 2.4 4.8 Site 5 7.9 0.24 0.15 0,2 6. 3 2. 8 2. 3 7.8 2.7 2 . 8 8. 5 3,6 2.4 Site 1· and 2 are in the same lo~ation. Site 1 was fertilized N+S. - 117 -Mo levels from a sandy soil location at Theodore. Copper deficiency experiencedin cattle grazing than soils could be a straight Cu deficiency or a Cu X Mo reaction according to Clark's criteria. Similarly, data from the saline soil area south of Quill Lake (Table 3) exhibited low levels of Table 3 . Forage copper and molybdenum samples in saline soils. Alfalfa Native Native Native pH 7. 6 8.0 8.4 8.1 DTPA Cu 0.34 0.40 1. 24 1.12 Ext. Mo 0.14 0.47 0.14 0. 38 E.C. 0. 5 10.2 19,6 11.9 Cu } 8.4 7.6 9.1 10.9 Mo · May 1.2 0. 5 0. 8 0.3 Cu:Mo 7.1 14.4 11.3 40.3 Cu } 13.1 7.9 16.9 15.6 Mo July 2. 7 0. 9 0.7 1.3 Cu:Mo 4.9 21.1 23.3 12.4 copper in the forage although Cu:Mo ratio were above deficient levels. Th~ uptake of molybdenum appeared to be depressed by high salt content in the soil. In this and at other locations it also was observed that molybdenum uptake by alfalfa was greater than that from native grasses on the same soil. T~ble 4 shows data from sandy soil sites (Bucis) Table 4, Forage samples. R. Bucis Nat~ve 'Pasture pH 8.2 E. C. 0.2 DTPA Cu* 0.16 DTPA Mo~" 0.10 Cu } 8.7 Mo May 2.4 Cu:Mo 3.7 Cu } llo2 Mo July 3.7 Cu:Mo · 3.1 Cu J 21.1 Mo Sept. 2.4 Cu:Mo 8.9 *0-15 em B. Petracek Brome/Alfalfa 8.0 0. 5 0.54 0.20 10.7 2. 0 5. 3 17.4 3. 5 5.1 11.7 1.6 7.4 B. Petr.acek Native Grass 7. 6 1.6 1.20 0.26 12.6 1.8 7.1 19.8 2.4 8.4 24.1 1.1 22.9 - 118 -where the level of soil available copper was low and forage copper reflected this assessment. Soil Analyses Soil copper values showed a reasonably good correlation with plant Cu values (Table 5) with the DTPA Cu from the 0-15 em depth providing the best correlation with plant copper. Extractable soil molybdenum showed no correlation with plant levels and a better method of assessment will have to be found, Table 5. Soil test correlations. Extractable Cu DTPA Cu (0-15 em) v v v v v Plant Plant Plant Plant Plant Cu Cu Cu Cu Cu June 0.51 .,, )'¢ July 0.62~'d~ August 0.72'ln'~* Sept. 0.52~'d~ v All Plant Cu 0.83~~*'~~ Extractable Mo v Plant Mo (No significant correlation) Water Analyses Water samples (Table 6) showed a wide range of salt Table 6 . Chemical assessment of water available for animals at 15 locations. Location· Location B Mo Cu Zn s No. s . Johnson 1 0.60 0.04 0 0.01 2 w. Johnson 2 0. 20 0. OS 0 0 216 (unfiltered system) w. Johnson 3 0.44 0. 0 5 .0 0 13 (slough) Clark 4 0.29 0.03 0 0.005 108 (home \ dugout) Salkald 6 0,25 0 0.005 0 60 (creek) Petracek 7 o. 6 3 0.05 0.01 0.04 1134 (pressure. system) Murphy 11 1.10 0,09 0.01 0.01 39 (slough) Cond. 0.14 0.52 0. 20. 0.16 0. 60 2.59 0.32 - 119 -Table 6 . Con 1 t Location Location B Mo Cu Zn s Cond. No. R. Bucis 12 0,58 0.07 0 0 63 0.30 (dugout) Stricker 13 1. 72 0.20 0.02 0.01 567 1. 33 (slough) Fould 14 0.21 0. 0 3 0 0 81 0.18 (creek) M. Royal 23 0,46 0.03 0.01 0 297 0,66 (Foam Lake creek) Barber 25 1.14 0.11 0.005 0.01 729 1.60 (lake) Oliver #2 26 0,77 0.06 0.01 0.005 891 1. 73 (dugout) Lazy 8 28 0.37 0.03 0.01 0.01 432 0.90 (Dafoe slough) Craven 32 0.78 0.05 0.01 0.02 810 1. 65 (slough) ---------------------------------~----------------------Low 0.20 0 0 0 2 0.14 High 1.72 0.20 0.02 0.02 1134 2.59 Medium 0.64 0.06 0.01 0.01 363 0.86 c6ntent as shown by conductivity and sUlphate values. Molybdenum, zinc and copper values were all low. Boron values varied with conductivity. The high sulphate content in some water samples could cause problems with copper uptake by animals at location Na. 7, 13, 25, 26 and 32. Sulphate levels in forage were not available for discussion at the time of this report. Comparison of Cu X Mo X S interactions will be completed at a later date. Summary A survey of soil and forage samples carried out during the summer of 1976 has shown that copper ~eficiency in animals could be caused by low copper herbage content inilocations in Eastern Saskatchewan. Copper deficiency also could be the result of a copper X molybdenum interaction caused by low Cu:Mo ratios in pastures. Potentially deficient Cu areas could be partially - 120 -diagnosed by extractable soil copper values. Extractable soil molybdenum values were not of use as they did not correlate with plant uptake--this may be du~ to higher uptake of ~olybdenum by tame species. References Brockman, R.P. 1976. Copper status in Saskatchewan cattle. Mimeo, Report to Sask. Dept. of Agriculture. Brockman, R.P. 1977. Concentration of copper in the livers of Saskatchewan cattle at alaughter. Can. Vet. J. (in press). Christensen, D.A. and M.A. Cochran. 1975. Copper require-ment of beef and dairy cattle. Mimeo. Review to Dept. of Animal Science, Univ. of British Columbia. Clark, K. and R. Drysdale. 1974. Botanical survey of North West region of Manitoba. Report t6 Manitoba meeting in 1974. Fletcher, P.J. and K. Doyle. 1971. Molybdenum content of bedrock, soils and vegetation and the incidence of copper deficiency in cattle in western Manitoba. Mimeo. Report to Dept. of Geological Science, Univ. of British Columbia. Gupta, V.C. and L.B. McLeod. 1975. Effects of S and Mo on the Mo, Cu and S concentration of forage crops. Soil Sci. 119: 441-447. Heil, R.D. and R.H. Follet. 1972. ST.S. Soil test interpretation guide and recommendation for copper and manganese in Colorado. Mimeo. Report to Soil Testing Lab at Colorado State University. Henderson, J.R. 1957. Can~dian cattle. Conditional copper deficiency in Can. J. Comp. Med. 21: 332-335. Lindsay, W.L. and W.A. Norvell. 1969. Development of a STPA micronutrient test. AgrQn. Absts. p. 84. Marsden, H.A. 1952. Cobalt, copper and molybdenum in the nutrition of animals. Physiol. Revs. 32: 66-121. Miltmore, J.E. and J.L. Mason. 1971. Copper to molybdenum ratio and molybdenum and copper concentration in ruminant feeds. Can. J. Anim. Sci. 51: 193-200. Miltmor•, J.E., J.L. Mason. J.M. McArthur and R.B. Carson. 1964. Ruminant mineral nutrition. Can. J. Comp. Vet. Sci. 28: 108-112. - 121 -Miltmore~ J.E., J.L. Mason, J.M. McArthur, C.C. Strachan and J.B. Clapp. 1973. Response from copper and selenium with vitamin E injections to cattle pastured on mineral and orianic groundwater soils .. Can. J. Anim. Sc~. 53: 237-24l.j.. National Research Council. 1970. 1971. of beef cattle, 4th review edition. of dairy cattle, 4th review edition. D, C. Nutrient requirements Nutrient requirements NAS-NRC; Washington, Nicholas, D.J.D. and A.R .. Egar. 1974. Trace elements in soil-plant-animal systems. Academic Press, New York. Stewart, J.W.B. 19£9. Micronutrients in Saskatchewan soils. Repovt to West Sci. Nut. Soil Fert. Comm., Edmonton. pp. 24-35. Vleck, P. and W.L. Lindsay. 1975. (Private communication). Molybdenum extractants. 

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Copper and molybdenum status of pastures in eastern Saskatchewan

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