macromineral status of sheep in the paramo region of colombia

SmalI Ruminant Research, 5 ( 1991 ) 9-21 9 Elsevier Science Publishers B.V., Amsterdam

Macromineral status of sheep in the Paramo region of Colombia

R. Pastrana a, L.R. McDowel l b*, J.H. Conrad b and N.S. Wilkinson b alnstituto Colombiano Agropecuario, Tibaitata, Apdo. Aereo 151123 Eldorado, Bogota, Colombia

bAnimal Science Department, University of Florida, Gainesville, FL 32611-0691, USA

(Accepted 13 July 1990)

ABSTRACT

Pastrana, R., McDowell, L.R., Conrad, J.H. and Wilkinson, N.S., 1991. Macromineral status of sheep in the Paramo region of Colombia. Small Rumin. Res., 5:9-21.

The macromineral status of pregnant-lactating ewes, lambs, and yearlings on three farms in the Paramo region of the Cordillera Oriental in Colombia was studied. Soil, forage, blood and rib bones were sampled during the end of the rainy season (May-June, 1987) and the middle to end of the following dry season (February, 1988 ). Season affected (P< 0.05 ) soil concentrations of Ca, Na, and forage concentrations of Mg, K, P and crude protein. Soil analyses of the three farms showed high concentrations of organic matter (19%) and low pH values (5.0). Magnesium was most deficient in both seasons at 70%, followed by K with 52% of the samples, and P 46%. Sodium was most deficient in forages with 93%, P was only deficient in the dry season (62%), and Mg was 53% deficient. Crude protein was deficient in only 6% of the forage samples. Blood serum analyses showed P deficiency in 59%, and Ca in the dry season at 94%. Bones were 98% deficient in Ca and P. Differences (P<0.05) among animal classes were found in serum P in both seasons (lambs were higher), in serum Mg in the dry season (lambs were lower), and in bone ash in the rainy season (lambs were lower). Along soil minerals and corresponding forage minerals, only Ca and Mg had positive correlations (P< 0.05, r> 0.50) for both seasons. From these analyses it was concluded that the macromineral status of sheep in the Paramo needs supplementation with common salt, Ca, P and Mg.

INTRODUCTION

Sheep are adapted to the cold and harsh environment of the Colombian Paramo but the few forage species grown are of low quality, and regrowth is slow after grazing. Under these conditions animals do not get their nutritional requirements and sheep enterprises may not be efficient. Poor growth rate of lambs, low fertility of, in particular, imported breeds, high mortality and low wool production with inferior quality are typical for sheep production in the Colombian Paramo (Proyecto Ovino Colombo Britanico, 1979).

Mineral deficiencies, imbalances, and toxicities have been reported to in-

*Author for correspondence.

0921-4488/91/$03.50 © 1 9 9 1 - Elsevier Science Publishers B.V.

10 R. PASTRANA ET AL.

hibit tropical ruminant production systems (McDowell, 1985 ). With the ex- ceptions of Ca and S, none of the macrominerals may have adequate concentrations in some forage species grazed by sheep on the Paramo (Laredo et al., 1989). The objectives of this study were to evaluate the macromineral status of grazing sheep and to determine soil, forage, and blood parameters on three farms during the wet and dry seasons of the Colombian Paramo. A second study (Pastrana et al., 1991 ) evaluated trace element status of these sheep.

M A T E R I A L S A N D M E T H O D S

Sample collection Soil, forage, and animal tissue samples were collected on three sheep farms

in the Paramo of the Cordillera Oriental of Colombia during the end of the rainy season (May-June, 1987) and the middle to end of the following dry season (February, 1988).

A total of 113 composite soil, 131 composite forage, 207 serum, 192 whole blood, and 147 rib bone biopsy samples were obtained during each sampling period. Samples from animals were divided into: lactating (or pregnant) ewes, lambs ( 1-4 months of age) and yearlings ( 10-14 months). Sheep were Criollo X Romney or Criollo × Corriedale in San Jorge and Criollo-Blackface in Don Benito and San Francisco.

Composite soil samples were from 8-12 subsamples according to Bahia ( 1978 ). Standard analyses were made in the Laboratorio Nacional de Suelos of ICA in Bogota for organic matter, pH, A1, Ca, Mg, P, K and Na. Minerals were extracted from the soil samples with a 0.025 N HzSO4 plus 0.05 N HC1 solution.

Based on texture, the soil of the upper part (above 3000 m) of San Jorge loamy (about 50%) or silt loam (about 50%); about 40% of the lower part soil (below 3000 m) is clay, 40% between clay loam and sandy clay loam; the rest is sandy clay, loam, and sandy loam. In Don Benito, the predominant soil is loamy, and in San Francisco it is loamy or silt loam.

Each composite forage sample came from 20-25 samples of the same forage predominating species that was most frequently grazed by sheep on the farms. Forage species collected were: vernalgrass (Anthoxantum odoratum), native velvetgrass (Holcus lanatus L), imported velvetgrass (Holcus lanatus basyn), kikuyugrass (Pennisetum clandestinum ), white clover (Trifolium re- pens), tall fescue ( Festuca arundinacea ), and orchardgrass ( Dactylis glom- erata). Each farm maintained about three sheep/ha/year under a rotational grazing system. There was no fertilization program in San Jorge; however, some paddocks of the lower part received nitrogen (urea) at 50 kg/ha/year. In Don Benito and San Francisco, pastures were not fertilized, however, some paddocks have the advantage of residual fertilization as a consequence of po-

MACROMINER ~L STATUS OF COLOMBIAN SHEEP 1 1

tato cropping. Forage samples were processed and analyzed for mineral content according to the method of Fick et al. ( 1979 ).

Duplicate blood samples were from jugular puncture. Bone biopsy samples were taken as described by Little (1972), with some modifications of the technique. The biopsy was taken without using a trephine; instead, a piece of bone approximately 2 cm in length was removed by cutting a section of rib using a small stainless steel bone shear.

Analyses Forage Ca, Mg, K and Na; serum Ca, Mg, Cu and Zn; and bone Ca and Mg

were determined by atomic absorption spectrophotometry with a Perkin-E1- mer AAS 5000 (Perkin-Elmer, 1980). Forage, serum and bone P were determined by the colorimetric method of Harris and Popat (1954). A limited number of forage samples (23) was analyzed for S with a LECO Model SC 132 sulfur determinator. For nitrogen analysis, forage samples were digested in a modified ~duminum block digester according to the method of Gallaher et al. ( 1975 ). In vitro organic matter digestibility (IVOMD) was performed by a two-stage ,modification of the technique of Moore and Mott (1974).

Whole blood samples were processed at the Laboratorio de Investigaciones Medico Veterinarias (LIMV) of lCA in Bogota for hematocrit, hemoglobin, total and differential leucocyte counts. Hemoglobin concentration was obtained by 'the oxyhemoglobin method, and for total leucocyte counts, a Coul- ter counter model FN was used (Schalm and Nemi, 1986).

Statistical design Data were analyzed by Statistical Analysis System (SAS, 1985 ). Soil and

forages we, re analyzed as a split-plot design, with the three farms as the main plot and season as subplot. Animal tissues were analyzed as split-plot design with animal classes as the main plot and season as subplot. Significance level was limited to 0.05 in all statistical analyses. Since the data were unbalanced, hypothesis testing was based on Type IV sum of squares. Correlation coefficients among minerals were determined.

R E S U L T S A N D D I S C U S S I O N

Soil analyses Soil organic matter (Table 1 ) was lower (P<0.05) on the San Jorge farm

during the rainy season, but pH was higher (P< 0.05 ) during the dry season. Reid and Horvath ( 1980) indicated that maximum rate of cation absorption occurs at pH 5-7. Soil acidity problems are associated with pH levels lower than 5.5 and the presence of exchangeable A1 in the soil (Sanchez, 1976). Don Benito had a higher (P< 0.05 ) A1 concentration during the rainy season and the lowest soil pH (4.8) of the three farms.

12

TABLE 1

Soil analyses by season and farms (dry basis)

R. PASTRANA ET AL.

Variable Sea- San Jorge son

Don Benito San Francisco Overall

Mean 1'2 % Deft- Mean %Deft- Mean % Deft- Mean % Defi- cient cient cient cient

Organic matter, %

pH

AI, p.p.m.

Ca, p.p.m.

P, p.p.m.

Mg, p.p.m.

K, p.p.m.

Na, p.p.m.

rainy dry rainy dry rainy dry rainy dry rainy dry rainy dry rainy dry rainy dry

10.6_ + 1.77 f 20.7+ 1.12 ~ 27.7+0.99 e 19.6 12.5-+2.10 19.6-+0.72 23.1 -+0.93 18.2 5.1 -+0.04 4.8_+0.08 5.0_+0.03 5.0 5.5 _+ 0.07 e 4.8 _% 0.08 f 4.9 _+ 0.03 f 5.1

142 _+27.1 f 575 _+77.7 e 316 +15.5 ef 344 93 -+8.66 439 -+81.3 428 +33.5 368

903 _+ 104 ~ 0 252 +66.1 f 32 278 _48.3 f 30 481 h 20 960 _+130 0 273 _+122 50 293 _+48.4 10 535 g 17

18.9_+3.39 50 51.6_+10.5 32 19.0+3.14 55 29.4 46 17.4-+2.97 55 32.1+4.73 21 28.6-+3.55 35 25.4 39

193 _+32.6 c 25 25.2+3.89 f 68 17.7+1.90 f 90 79.4 61 157 -+29.5 40 13.2+2.12 93 28.5-+1.05 100 68.3 76 65 -+10.9 55 107 -+8.71 0 63 _+6.77 55 77.6 37

108 _+11.3 25 33 -+4.55 100 51 -+5.56 70 67.4 61 32.8 -+ 3.60 ~ 4.2_+ 0.94 f 2.3 + 0.0 f 13.3 ~ 17.3___3.33 2 .5+0.16 2.8_+0.32 8.1 h

~Means based on the following number of composite samples: 20, 20 in San Jorge, 19, 14 in Don Benito and 20, 20 in San Francisco, for rainy and dry seasons, respectively. 2Standard error of mean. 3Critical levels (p.p.m.) are: Ca, 71 p.p.m. (Breland, 1976); P, 17; Mg, 30; and K, 62 (Rhue and Kidder, 1983 ). Critical levels derived from Florida soils. ~'rMeans among farms in a row with different superscripts differ (P< 0.05 ). g'hMeans between seasons in a column with different superscripts differ (P< 0.05 ).

Soils were most deficient in Mg in relation to critical levels; 6 I% of the samples were below 30 p.p.m. (Rhue and Kidder, 1983 ) in the rainy and 76% in the dry season. San Jorge had the highest levels ( P < 0.05 ). Metson (1974) found evidence that acidity aggravates a Mg deficiency condition.

San Jorge had higher concentrations ( P < 0.05 ) during the rainy season in Ca, Mg, and Na and lowest P level, but this was not significant ( P > 0.05 ). Phosphorous was 46% deficient in the rainy and 39% in the dry season. Many tropical soils are reported to be generally deficient in P (Volkweiss, 1978 ).

Thirty seven percent of the samples in the rainy season and 61% in the dry season were below the critical level of 62 p.p.m, suggested for K (Rhue and Kidder, 1983 ). Sodium level was very low on the three farms, especially Don Benito and San Francisco.

Forage analyses Forage macromineral, crude protein and IVOMD concentrations are in Ta-

ble 2. Even though forage samples were separated by species, they could not

MACROMINER ~L STATUS OF COLOMBIAN SHEEP 13

TABLE 2

Forage mineral, crude protein and IVOMD concentrations by season and farms (dry basis)

Variable Sea- San Jorge Don Benito San Francisco Overall son

Mean ',2 % Deft- Mean % Deft- Mean % Deft- Mean cient cient cient

% Defi- cient

Ca, %

K,%

Mg, %

Na, %

P,%

CP, %

IVOMD, %

rainy dry rainy dry rainy dry ramy dry rainy dry rainy dr~ rainy dI3

0 .50+0.07 4 0 .31+0.04 5 0.24_+0.02 37 0.37 13 0.35_+0.05 13 0.25_+0.02 40 0 .29+0.02 20 0.31 22 2.75_+0.18 0 3 .28+0.14 0 2.19_+0.12 0 2.75 g 0 1.53_+0.11 3 1.64+0,19 0 1.03_+0.06 0 1.40 h 1 0.21+0.01 21 0 .13+0,00 40 0 .13+0.00 37 0.168 31 0.13+0.01 e 50 0 .08+0.00 f 100 0 .09+0.00 f 95 0.11 h 75 0.04-+0.00 89 0.03-+0.00 100 0 .05+0.00 89 0.03 93 0.04-+0.00 97 0.05_+0.01 87 0.03_+0.00 95 0.04 94 0.28_+0.01 7 0.30_+0.01 0 0.20_+0.00 0 0.27 g 3 0.17_+0.01 47 0.16+0.01 60 0.12-+0.00 85 0.15" 62

17.5 _+1.00 0 20.6 _+0.97 0 17.4 +_0.89 5 18.4 g 1 11.7 _+0.79 13 14.7 _+1.82 7 10.6 +_0.62 10 12.0 n 11 58.7 +2.03 r 71.1 _+1.00 e 72.7 +1.22 ¢ 66.7 57.6 _+1.36 58.9 _+2.58 53.8 _+1.10 56.7

tMeans based on the following number of composite samples: 28, 29 in San Jorge, 20, 15 in Don Benito and 19, 20 in San Francisco, for rainy and dry seasons, respectively. 2Standard error of means. 3Critical leveL,; (%) suggested by NRC ( 1985 ) are Ca (0.2), K (0.5), Mg (0.12), Na (0.09) and P (0.16), for CP ( 7 ) (Minson and Milford, 1967 ). ¢SMeans among farms in a row with different superscripts differ ( P < 0.05 ). g'hMeans between seasons in a column with different superscripts differ (P< 0.05 ).

be included in the statistical model because of the uneven occurrence of some, which produced a large number of empty cells.

Lower liimits of sheep mineral requirements (DM basis ) (NRC, 1985 ) were used to calculate the percentage of deficient forage samples. Na was most deficient in forage samples (93-94%) according to the critical level of 0.09% (NRC, 1985 ). Potassium was least deficient (only 1% ). This element is often associated with high levels of nitrogen and moisture in lush, cool-season grasses (Boling el: al., 1979). Magnesium was 31 and 75O/o deficient during the rainy and dry seasons, respectively. Phosphorus was only 3% deficient in the rainy but 62% in the dry season. Underwood ( 1981 ) stated that P deficiency is the most widespread and economically important mineral deficiency of grazing livestock. Thirteen and 22% of forage samples were Ca deficient in the rainy and dry seasons, respectively. Results are in contrast to researchers in the Latin American~ tropics who have reported relatively low Ca and extremely deficient forage concentrations (McDowell, 1985 ).

Only 1% of the samples in the rainy and 11% in the dry season were deficient for (:rude protein, i.e., below a critical value of 7% suggested by Minson and Milff,rd, 1967. The high protein concentration in this study agrees with Laredo and Anzola ( 1986 ) who determined crude protein level in temperate


grasses similar to those in this study. Sanchez ( 1976 ) stated that soil organic matter supplies most of the nitrogen and half the phosphorus taken up by unfertilized crops.

San Jorge forage sample Mg was higher (P< 0.05 ) during the dry season but deficiency was also high ( 50% ). Michael ( 1962 ) reported that serum Mg levels in sheep were not correlated with herbage Mg content, but Fontenot (1982) stated that an Mg deficiency in ruminants may result from low Mg concentrations in feeds or reduction in biological availability of dietary Mg. Nitrogen level, stage of maturity, excessive K level, form of Mg, and amount of readily fermentable carbohydrates have been considered as components of Mg utilization (Rosero et al., 1980).

The Ca, K, P, Na and crude protein concentrations of forages were not different (P> 0.05) among the three farms. IVOMD was lower (P< 0.05) for San Jorge during the rainy season but not during the dry season. Values were not low (58.7 and 57.6%) and those for Don Benito (71.1 and 58.9%) and San Francisco (72.6 and 53.8%) are considered high, which implies that the animals were receiving good quality forages, especially during the rainy season. Since IVOMD values were relatively high, it seems that yields of forage DM/ha in the Paramo is more a limitation of animal performance than forage quality. Laredo et al. (1989) found that the production of DM/ha in Don Benito was 2.8 tons and 2.0 tons for H. lanatus basyn (imported cultivar) and H. lanatus L (native cultivar); in San Francisco, 2.8 tons and 0.8 ton, respectively. These figures were low for this grass (Watt, 1978) and even lower when compared with other temperate grasses.

Crude protein, Mg, K and P were lower (P< 0.05 ) during the dry season. Although Na was not different (P> 0.05 ) between seasons, concentrations indicated that there was a serious deficiency at all times. Calcium had similar values in both seasons. McDowell et al. ( 1983 ) stated that as plants mature, mineral concentrations decline due to a natural dilution process and translo- cation of nutrients to the root system. In most circumstances, Mg, P, K and Na decline as the plant matures. Crude protein declined from 18.4% to 12% (P< 0.05 ). In vitro OMD also declined, from 66.7% to 56.7%, but the differ- ence was not significant (P> 0.05 ). Sulphur analyses of 23 samples averaged 0.24%, ranging from 0.11 to 0.36%. Only two samples were less than the re- quirement of 0.18% (NRC, 1985).

Blood serum analyses No differences were found (P> 0.05) among farms for serum Ca and P

during the rainy and dry, and for Mg during the rainy season. Magnesium had a higher value (P<0.05) on San Jorge farm (2.18 mg/dl) than at San Fran- cisco ( 1.93 mg/dl) during the dry season (Table 3 ).

Lambs had higher (P<0.05) concentrations of serum P than ewes (5.2, 5.6 vs. 3.6, 2.5 mg/dl) in the rainy and dry seasons, respectively; and more

MACROMINERAL STATUS OF COLOMBIAN SHEEP 15

(P< 0.05 ) than yearlings but only in the dry season (4.0 mg/dl) . In contrast, lambs had lower (P< 0.05 ) values of serum Mg than yearlings in the dry season. There were no differences (P> 0.05) for serum Ca among the three animal classes.

The general tendency was for the dry season to have lower values of Ca, Mg and P; nevertheless, P was the only element statistically affected (P< 0.05 ) by season (4.71 vs. 3.99 mg/dl ). Calcium below critical levels (McDowell et al., 1984) was 3% for the rainy and 94% for the dry season. At San Jorge, Don Benito and San Francisco during the dry season, Ca was 100, 97 and 87% deficient, :respectively; for ewes, lambs and yearlings Ca was 100, 74, and 100% deficient respectively, during the dry season. High incidence of serum samples below the critical level indicated that sheep had a very severe Ca deficiency during the dry season. Sheep and cattle have hormonal mechanisms which maintain blood Ca concentrations within narrow limits by adjusting the proportion of dietary Ca absorbed and, when dietary Ca is inadequate, by resorbing Ca from body reserves in the skeleton (Rowlands, 1980). Black et

TABLE3

Blood serum and bone mineral concentrations by season and farms

Variable Sea- San Jorge Don Benito San Francisco Overall son

Mean 1'2 % Deft- Mean % Deft- Mean % Deft- Mean % Deft- cient cient cient cient

Serum Ca, mg/dl rainy 10.1_+0.1 3 10.0_+0.2 6 10.4_+0.12 0 10.1 3

dry 6.2_+0.1 100 6.1 _+0.1 97 6.5+_0.18 87 6.3 94 P, mg/dl rainy 4.7_+0.23 53 5.0+_0.3 42 4.4+_0.37 58 4.7 f 51

dry 3.9_+0.2 71 4.4+_0.2 62 3.8_+0.25 67 4.0 ~ 67 Mg, mg/dl rainy 2.2_+0.04 8 2.1+_0.1 33 2.2-+0.05 25 2.1 22

dry 2.2+0.1 d 41 2.0_+0.1 °~ 47 1.9+0.05 e 61 2.0 51 Bone (D.M., fat-free) Ash, % rainy 62.1_+0.5 100 62.3+-0.6 100 63.4_+0.4 100 62.6 100

dry 59.4+_ 1.6 85 65.2_+ 1.1 88 62.4+_0.4 96 61.7 89 Ca,% rainy 22.1_+0.3 100 22.2+_0.3 100 22.0_+0.2 100 22.1 100

dry 20.2_+0.6 100 23.3+_ 1.3 88 21.1 _+0.3 100 21.2 97 P,% rainy 7.8+0.3 100 6.8_+0.7 95 7.3_+0.3 100 7.3 99

dry 5.9_+0.3 100 8.2_+0.6 94 6.8_+0.3 100 6.7 99 Mg, °/o rainy 0.4_+0.0 0.4_+0.0 0.4_+0.0 0.4

dry 0.3_+0.0 0.4_+0.0 0.4+0.0 0.4

1Means based on the following number of samples: serum 36, 34 in San Jorge farm, 33, 34 in Don Benito and 24, 46 in San Francisco. Bone 26, 33 in San Jorge, 22, 16 in Don Benito and 25, 28 in San Francisco, for rainy and dry seasons, respectively. 2Standard error of means. 3Critical lew:ls (McDowell et al., 1984); serum (mg/dl), Ca (8), P (4.5) and Mg (2); Bone (%), ash (66.8), Ca (24.5) andP ( l l .5) . d'eMeans among farms in a row with different superscripts differ (P< 0.05 ). f'SMeans between seasons in a column with different superscripts differ (P< 0.05 ).


al. ( 1973 ) reported that serum Ca concentrations may be directly affected by dietary Ca intake, and Steevens et al. (1971) found that serum Ca is more affected by amounts of P and Mg in the diet than by Ca itself. Serum Ca, however, is influenced only by severe deficiency, and Ca dietary level may be a more adequate criterion in assessing status of Ca (CMN, 1973 ).

Serum inorganic P was deficient in 51% of the samples during the rainy and 67% during the dry season, i.e., below 4.5 mg/dl (McDowell et al., 1984). Deficiency of P for San Jorge, Don Benito, and San Francisco farms was 53, 42, and 58% during the rainy and 71, 62, and 67% during the dry season, respectively. Deficiency of serum P for ewes, lambs and yearlings was 84, 38 and 23% during the rainy and 97, 19 and 72% during the dry season. Plasma inorganic P concentrations are maintained by absorption of P from the gut, and there is no specific mechanism for bone P resorption (Jacobson et al., 1972 ). Positive relationships between dietary P intake and plasma inorganic P have been observed (Rowlands, 1980). However, serum or plasma P is not recommended as a practical criterion for assessing P status in cattle or sheep by some researchers (CMN, 1973).

Twenty two percent of samples were below 2 mg/dl of Mg (McDowell et

TABLE 4

Blood serum and bone minerals by season and animal class

Variable Sea- Ewes Lambs Yearlings Overall son

Mean L2 % Deft- Mean % Deft- Mean % Deft- Mean % Defi- cient cient cient cient

Serum Ca, mg/dl rainy 9.60+0.15 8

dry 5.95-+0.14 100 P, mg/dl rainy 3.62+0.19 e 84

dry 2.54-+0.16 97 Mg, mg/dl rainy 2.15-+0.05 27

dry 1.96 + 0.07 de 52 Bone (D.M., fat-free) Ash, % rainy 64.2 +0.32 d 100

dry 65.8 -+0.40 70 Ca,% rainy 22.8 -+0.18 100

dry 22.4 _+0.20 100 P, % rainy 7.84-+0.22 100

dry 7.32-+0.16 100 Mg, % rainy 0.34_+0.01

dry 0.34+-0.01

10.13+-0.16 0 10.53-+0.09 0 10.1 3 7.14+0.24 74 6.05-+0.08 100 6.28 98 5.18+0.30 d 38 5.58+0.24 d 23 4.71 f 51 5.62+0.26 d 19 4.00-+0.12 72 3.99 s 67 2.01-+0.09 29 2.21-+0.04 11 2.14 22 1.84+0.04 ~ 81 2.14_+0.04 d 35 2.02 51

60.3 _+0.60 r 100 61.7 +0.37 e 100 62.6 100 59.4 +1.51 100 63.6 +0.51 95 61.7 89 21.3 +_0.19 100 21.5 +0.23 100 22.1 100 16.7 +0.54 100 21.9 -+0.52 95 21.2 97 5.25+0.58 100 7.60-+0.47 96 7.32 99 4.77+0.28 100 7.07-+0.32 98 6.73 99 0.40+-0.01 0.37+-0.01 0.36 0.32+-0.01 0.40-+0.01 0.37

~Means based on the following number of samples: serum 37, 33 in ewes, 21, 27 in lambs and 35, 54 in yearlings; Bone 34, 20 in ewes, 14, 13 in lambs and 25, 44 in yearlings, for rainy and dry seasons, respectively. 2Standard error of means. 3Critical levels (MeDowell et al., 1984); serum (mg/dl, Ca (8), P (4.5) and Mg (2); Bone (%), ash (66.8), Ca (24.5) and P (11.5). d.e,fMeans among animal classes in a row with different superscripts differ (P< 0.05 ). ~'hMeans between seasons in a column with different superscripts differ (P< 0.05).


al., 1984) during the rainy and 51% during dry season. The deficiency was 41, 47 and 61% on San Jorge, Don Benito and San Francisco during the dry season. For ewes, lambs and yearlings Mg was 52, 81 and 35% deficient during the dry season. In contrast to Ca, serum Mg concentration depends mainly on the dietary intake of available Mg (Rowlands, 1980). Levels below 2 mg/ dl in plasma are classed as hypomagnesaemic, but Mg concentration in blood serum does not fall until there is a severe deficiency (CMN, 1973 ).

Bone analysis There was no season nor farm effect (P> 0.05 ) for any bone parameters

with the exception that ash level during the rainy season varied among animal classes, with ewes higher (P< 0.05 ) than yearlings (64.2 vs. 61.7%), and lambs lower (P< 0.05) than both classes at 60.3%. Greater mineralization would be expected in mature animals.

Individual evaluation of samples indicated that ash concentration below a critical level of 66.8% (McDowell et al., 1984), was 100% during the rainy and 89% during the dry season. Spongy bone of the axial skeleton is the first to demineralize in periods of negative balance (Little, 1972).

Bone Ca concentrations were below the suggested critical levels of 24.5% (McDowell et al., 1984). Deficiencies were 100% for the rainy and 97% for the dry season, agreeing with Knebush et al. (1986) and Tejada et al. (1987) who reported that when animals were evaluated by blood serum and bone samples fi~r Ca status, a higher number were below the critical levels based on bone analysis as compared to critical levels in serum. This also supports the concept that cattle or sheep resist depletion of plasma Ca through mobiliza- tion of bone Ca, thus making bone a more accurate indicator than serum Ca levels in animals.

Mean rib bone P was 99% deficient during rainy and dry seasons, based on critical levels of 11.5% (McDowell et al., 1984). This agrees with other work with cattle in the tropics (Tejada et al., 1987; Vargas et al., 1984). Adequate forage P concentration appears to be reflected more accurately in plasma P than bone P even though bone P seems preferred over serum concentrations for evaluation of the P status of animals (McDowell et al., 1983 ).

Bone Mg concentrations were similar among farms and among animal classes. Cohen (1987) suggested that bone Mg may be useful in assessing Mg status in grazing livestock.

Correlations among minerals Serum correlation coefficients (P< 0.05) of r+ 0.50 in serum were for Ca-

P ( r=0.76) , Ca-Fe ( r - 0 . 6 5 ) and Ca-Zn ( r - 0 . 7 7 ) during the dry season. For bone, the correlations were for Ca-ash (r = 0.79 ) during the rainy season, Ca-P ( r=0 .80) , and Ca-ash ( r=0.97) during the dry season. Other corre-


lations were for serum P-bone Mg (r=0.84) and serum Mg-bone P (r=0.85) during the rainy season.

In general, mineral concentrations in animal tissues did not correlate with each other greater or equal to 0.50 at the probability level of 0.05. This dem- onstrated the problem of finding significant correlations between soil, forage and animal tissues (Conrad et al., 1980).

Hematological measurements San Jorge had higher (P< 0.05 ) total leucocyte counts (Table 5 ) ( 16 838/

/tg) than Don Benito (7605//tg) and San Francisco (8107//~g) during the rainy but during the dry season the values were much lower for San Jorge and different only from San Francisco. Total leucocyte counts at San Jorge during the rainy season exceeded the normal limits in sheep of 12 000//~g (Schalm and Nemi, 1986 ). Differential leucocyte counts on the same farm, during the rainy season, showed that the percentage of lymphocytes exceeded the range of 75% (Schalm and Nemi, 1986).

There were no differences (P> 0.05 ) among animal classes for hematological measurements, but lambs in the rainy season exceeded the range limits (Schalm and Nemi, 1986) for leucocytes and lymphocytes, but were below that of 10% for mature neutrophils. Lambs exhibited slight to moderate leu-

TABLE5

Hemoglobin, hematocrit concentration and leucocyte counts by season and farm

Variable Range of Season San Jorge Don Benito San Francisco Overall levels I

Mean 2,3 Mean Mean Mean

Hematocrit,% 27-45 rainy 34.0 _+0.51 40.8 +0.67 40.3 _+0.68 38.0 Hemoglobin,gdl dry 34.8 +0.84 37.6 _+0.74 39.5 +0.69 37.4 Leucocytes,//d 9-15 rainy 11.4 _+0.15 13.6 +0.22 13.4 _+0.23 12.6 Neutrophils,% dry 11.8 +0.32 12.7 +0.27 13.4 +0.30 12.6

4000-12000 rainy 16838 +997 a 7605 +322 e 8107 +285 e 11458 dry 7277 _+316 a 6671 +369 a 4598 +186 e 6089

10-50 rainy 12.8 _+1.21 18.6 +1.92 26.0 + 1.97 18.0 dry 24.4 _+2.45 22.1 +1.98 31.0 _+ 5.49 26.3

Lymphocytes,% 40-75 rainy 84.8 _+1.43 76.5 +2.04 65.0 -+ 1.98 77.1 Monocytes,% dry 71.5 _+2.68 73.1 +2.23 70.3 +2.67 71.5 Eosinophils,% 0-6 rainy 0.72 -+ 0.15 1.50 -+ 0.21 2.00 _+ 0.66 1.3 Basophils,% dry 1.11 - + 0 . 2 2 1 . 3 4 _ + 0 . 2 4 0.63_+0.17 1.0

0-10 rainy 1.72+0.48 3.28_+0.79 7.00_+0.97 3.5 dry 2.56 _+ 0.50 2.66 + 0.55 2.88_+ 0.53 2.7

0-3 rainy 0.00 _+ - 0.09 -+ 0.06 0.00 -+ - 0.03" dry 0.42+0.11 0.76-+0.17 0.23+0.08 0.44 a

]Schalm and Nemi (1986). 2Means based on the following number of samples: 36, 36 in San Jorge, 32, 29 in Don Benito and 2 l, 40 in San Francisco, for rainy and dry seasons, respectively. 3Standard error of means. d'*Means among farms in a row with different superscripts differ (P< 0.05).

MACROMINER~L STATUS OF COLOMBIAN SHEEP 19

cocytosis, defined by WBC values of 13 000 and 20 000//zg (Holman, 1944 ) and this could mean that an infectious process was taking place in San Jorge lambs at sample collection time.

CONCLUSION

Common salt, P, Ca and Mg seem to be the minerals most limiting sheep production in the Paramo region of Colombia. Supplementation studies should be initiated to determine need and economic benefits of mineral supplementation.

ACKNOWLEDGMENTS

Florida Agricultural Experiment Station, Journal Series No. R-00305. This research was supported by the U.S. Department of Agriculture under CRSR special grant No. 86-CRSR-2-2843 managed by the Caribbean Basin Advi- sory Group (CBAG).

Appreciation is due to Dr. F.G. Martin and Dr. S. Linda for statistical as- sistance, Dr. O. Ospina (Caja Agraria) and Dr. A. Naranjo (ICA) for sample collection, to Dr. R. Lora for soil analyses and to Dr. J. Neira for whole blood analyses at the ICA laboratories.

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