JOURNAL OF THE SCIENTIFIC AGRICULTURAL SOCIETY OF FINLAND 468 Maataloustieteellinen Aikakaustyrja Vol. 12: 468-476, 1980 The effects of trace element supplements on blood levels of horses ESA KÄÄNTEE 66270 Pörtom, Finland PAAVO KURKELA 61800 Kauhajoki, Finland Abstract. This study concerns the effects of Se, Cu, Co, Mn and Zn supplements on blood levels of Finnish warm-blooded trotters. The results revealed that the blood Se content corresponding to the feed Se content of 0.1 mg/kg is 0.17 + 0.03 mg/kg in the horse. Blood Se level was directly related to the feed Se content and the other feed trace elements had a similar effect on blood levels. Introduction The maximal performances demanded of race horses require that the various blood sub-factors fall within optimal, often very narrow, ranges (WILLIAMSON 1974). These sub-factors, macro- and microminerals, are influenced by the horses feed (KOSSILA et al. 1974, KÄÄNTEE and KURKELA 1978). In addition to the poor performances, deficiency conditions are reflected in diseases such as muscle dystrop- hy arising from lack of Se (LANNEK and LINDBERG 1975). Because the Se content of Finnish fodders is poor (KÄÄNTEE et ai. 1978), particular attention has been paid to the Se supplement of horse feed. Selenium, together with vitamin E and biotin, acts as a cell membrane protective factor (WROGEMANN and PENA 1976). The effect of different Se compounds on the body Se level varies (KÄÄNTEE and KURKELA 1980). Both the body and feed levels of Se affect the behaviour of Cd, Hg, Cu, and Zn in the organism because of the interaction between various tra- ce elements (DAVIES 1974). In the studies performed the effect of feed factors on macro- and micro-minerals in the horse was investigated, with main attention focused on selenium. Material and methods Seven warm-blooded 4—B-year-old trotters in racing condition were used for the trials. The horses’ weights varied between 340 and 410 kg and all were raced during the studies. The fodders and feeding periods are shown in Table 2. The feed https://www.c-info.fi/en/info/?token=v6CjClqbHTZ1CT3T.lNyrBM_g_cd1IH1UmgTugA.RbyCXbWnsGqxegFmXcqX5AQGGnRAc86GnrHZ2ngxlIs6vyybP5_G2dpUJlCHCN-Iyx75LEXIfVxRTuEcE1GYpJiXY6AGBxlPAWE_CQHZi8s2QSg8WIaEyFCERft4N-LIq_EIKTdYpEKlxKzJiTtvJFVuIYFQe_5upLJceRIbZ0cMwyctRct2Sqe7MfFUGQfn_kc 469 Se level was altered by replacing part of the oats with barley rich in Se (0.68 mg/kg) during trial period 2. This increased the feed proportion of grain Se. During trial periods 4 and 5 the horses received 0.9 mg and 1.5 mg daily, respectively, of selenium as sodium selenite in a trace element mixture. The daily dose of trace ele- ments and vitamins was: iron 600 mg, copper 2 5 mg, zinc 150 mg, iodine 0.15 mg, cobalt 3.0 mg, manganese 70 mg, vitamin E 750 mg, vitamin B, 24 mg, vita- min B 2 20 mg, vitamin B 6 1 2 mg, vitamin 812B 12 1 mg, folic acid 12 mg and vitamin C 500 mg. The feed Ca, P and Se were determined at the Viljavuuspalvelu Oy company and the Oulu Research Laboratory of the Kemira Company (Table 1). Hb was determined as cyanmethaemoglobin, scrum alkaline phosphatase by the HUGGINS and TALALAY (1945) method, SCOT and SGPT by the REITMAN and FRANKEL (1957) method, serum total protein by the WECHSELBAUM (1946) biuret method, serum vitamin 812B l2 by isotope dilution analysis and folic acid by the DUNN and FOSTER (1973) method. Scrum Ca, P, Mg, Na, K, Fe, creatinine and urate analyses were carried out with a SMA/60 Autoanalyzer in the Oulu Deaco- ness Institute Laboratory, and blood Se, Mn, Cu, Co and Zn determined by Perkin- Elmer atomic absorption spectrophotometer at Viljavuuspalvelu. The blood samples were taken from the jugular vein during morning feeding on completion of each feeding period. On days prior to blood sample taking the horses did not take part in races or heats. Results The results of the blood Se analysis are shown in Table 2. They show that as the feed Se content rose the blood Se concentration also increased. A feed Se content of 0.1 mg/kg corresponded to a blood Se concentration of 0.17 ± 0.03 mg/kg. Table 3 shows analysis results of samples taken on completion of feeding peri- ods. The use of the trace element mixture clearly increased blood Cu, Mn and Zn concentrations. The freely available refined salt raised serum Na values. It was established clinically that during the use of the trace element mixture the general condition of the horses improved and the quality of the hair became better. Perspiration due to strain decreased and recovery was quicker. Racing performances also improved during the trial. Table I. Ca, P and Sc contents of the feeds given and daily amounts of feed used. Ca P Se Daily dose g/kg g/kg mg/kg of feed kg HAY 3 0 2.1 0.02 7 OATS 0.6 3.4 0.02 5 (3) BARLEY 0.6 3.4 0.68 (2) BRAN 1.2 13.6 0.13 0.7 5 PROMECA . 100 105 1 Table 2. Feeds of the horses during different feeding periods. Horses’ daily feed Sc intake and blood Se content on completion of the feeding period. 7 horses PERIOD 1 21 days PERIOD 2 28 days PERIOD 3 2 1 days PERIOD 4 28 days PERIOD 5 28 days HAY 7 kg HAY 7 kg HAY 7 kg HAY 7 kg HAY 7 kg OATS 5 kg OATS 3 kg OATS 5 kg OATS 5 kg OATS 5 kjOATS 3 kg OATS 5 kg OATS 5 kg OATS 5 kg BRAN 0.75 kg BARLEY 2 kg BRAN 0.75 kg BRAN 0.75 kg BRAN 0.75 kg PROMECA Ikg BRAN 0.75 kg PROMECA Ikg PROMECA Ikg PROMECA Ikg PROMECA 1 kg TRACE TRACE ELEMENT ELEMENT MIXTURE MIXTURE II Sco.o3mg/kg Se 013 mg/kg Sco.o3mg/kg ScO,lmg/kg SeO.Hmg/kg Se 0.42 mg/day Se 1.79 mg/day Se 0,42 mg/day Scl .32mg/day Scl .92mg/day (0.42) (1.73) (0.42) (0.42 + 0.9) (0.42 + 1.5) BLOOD Se 0.08 BLOOD Se 0.14 BLOOD Se 0.07 BLOOD Se 0.17 BLOOD Se 0.19 ± 0.04 mg/kg ±0.04 mg/kg ± 0.02 mg/kg ±0.03 mg/kg ± 0.04 mg/kg FREE ACCESS TO SALT Table 3 Analysed scrum and blood contents on completion of feeding periods (7 horses). The feeds given are in table 1. I: Basic feed 2: Part of the oats replaced by barley 4: Trace clement supplement during basic feeding 5: Trace clement supplement + salt (NaCl) supplement during basic feeding FEEDING PERIOD 1 2 4 5 Hbg/I 146 ±l4 144±2l 144 ±l2 155 ±22 Scrum GOT IU 321 ± 112 347 ± 216 291 ±7 5 335 ± 385 Serum GPT IU 13 ±8 12 + 4 Serum alkaline phosphatase IU 9.8 ± 2 11.5 ±2l 11 ±2.8 10 ±1.7 STPg/1 63 ±2 62 ±3 60 ± 3 63 ±4 Serum Ca mmol/1 2.84 + 0.07 2.78 ±0.05 2.74 ± 0.09 P 1.16 ± 0.16 1.12 ± 0.11 1.10± 0.21 Mg 0.81 ±0.14 0.75 ±0.05 Na 1 35 ± 2 134 ± 2 141 ± 2 K 4.1 ±O.l 3.8 ±0.2 4.0+ 0.2 ” Fc " ” 36.4 ± 3.3 30,1 ±6.8 Blood Cu ug/kg 779 + 395 749 + 369 2044 ±1613 ” Co ” ” 28.5 + 13.538.3± 15.324.4 ±6.4 Mn ” ” 38 ± 1 3.8 28.8 + 123 79.8 ±41.8 Zn mg/kg 2.67 ± 3.00 ± 0.63 3.19±0.61 Serum B,J ng/ml 1842± 194 2010±195 folic acid ng/ml 5.93 ± 1.2 7.33 ± 2.3 creatinine mmol/1 154 ± 9 153 ± 14 urate mmol/1 34 ±6 30 ±7 470 Discussion Selenium The blood Sc content of the horse depends on the feed Se content. The blood Se concentration of Finnish warm-blooded trotters has been measured as 0.18 ± 0.08 mg/kg (KÄÄNTEE ct al. 1978). Concepts of normal blood Se level differ greatly because of both variations in feed Se contents and inaccuracies in analytical methods employed. The Se requirement of animals is reported to be 0.1 mg/kg feed (NRC 1973). The fodder Se concentration 0.1 mg/kg fodder was consisted of the grain Se, 0.03 mg/kg, and of trace clement mixture, 0.09 mg/kg. The blood Se poncentration was established to be 0.17 ± 0.03 mg/kg, which is of the same order as the normal value established in the previous studies (KÄÄNTEE et al. 1978). The feed analyses carried out revealed the poor Se content ofFinnish feeds. The Se content of basic feed was 0.03 mg/kg, which is clearly less than the critical Se le- vel of 0.05 mg/kg below which not even large supplements of vitamin E can replace the lack of Se (JONES et ai. 1977). On basic feeding the blood Se content was 0.08 ± 0.04 mg/kg. Muscular dys- trophy has been established in horses with blood Se levels of 0.05 mg/kg or under (LINDHOLM et ai. 1978). On basic feeds, however, the blood Se content was abo- ve this critial level. In horses fed on Swedish domestic feeds the blood Se level va- ried between 0.01 mg/kg and 0.08 mg/kg (values calculated on the basis of the GSH-Px activity values of the HENNICHS and PEHRSON 1979 trial). The values established in the present study were slightly higher because brans rich in Se and Promeca were used. In Sweden, a Se supplement of 4.4 mg has been added to do- mestic feeds 2—4 times monthly to satisfy the Se requirement (HENNICHS and PEHRSON 1979). In the present trial daily Se supplements of 0.09 mg and 1.5 mg were added to supplement the normal feed of Finnish trotters. The feed Se content then rose to the NRC (1973) animal requirement level and blood Se content to va- lues of 0.17 ± 0.03 mg/kg and 0.19 ± 0.04 mg/kg, respectively. It has been established in hens that grain Se raises body and blood Se contents considerably better than sodium selenite added to feed mixtures (KÄANTEE and KURKELA 1980). This was not found in the present material. The barley used was rich in selenium, containing 0.68 mg/kg grain. The selenium content of test feed 2 was 0.1 3 mg/kg with grain Se, but the blood Se content was 0.14 ± 0.04 mg/kg. The selenium content of test feed 5 was almost the same at 0.14 mg/kg. Most of the supplied selenium was sodium selenite from the trace element mixtu- re; 0.03 mg/kg was grain Se and 0.11 mg/kg came from the trace element mixture. The blood Se content was 0.19 ± 0.04 mg/kg. The differences in blood Se con- tents were probably due to factors caused by gastrointestinal bacteria influencing se- lenium absorption (the bacteria transform selenium compounds) as well as to the ef- fects of vitamin C contained in the trace element mixture. (COMBS and PETO 1976) Copper The Cu requirement of the horse is s—B mg/kg feed, according to OLSSON (1 969). DREPPER (1972) recommends 10 mg Cu/100 kg bodyweight for racing horses. Low Cu contents have been found in the timothy grass of Northern Finland 4 471 472 (LAKANEN 1969). The Viljavuuspalvelu Company reports the mean Cu content of the hay of 1977—1978 as 4.4—4.6 mg/kg, of barley 5.5—5.1 mg/kg and of oats 3.9—5.3 mg/kg. The hay and oat Cu contents established by KOSSILA et al. (1972) were 6.7—7.4 mg/kg and 9.8—6.8 mg/kg, respectively, i.e. considerably higher than the values reported by Viljavuuspalvelu. The serum Cu content of horses in the material of KOSSILA et al. (1972) varied between 470 and 1140 ug/kg. According to KOLB (1967), the normal value for horses is 1300 ,«g/kg. MULLER-REH (1972) established the plasma Cu content of the horse to be 820—1210 g/kg while the feed Cu content varied between 1 1 and 3 1 mg/kg dry feed. According to EKMAN et al. (1975) the normal plasma Cu content is 1 530 ± 380 ng/kg. In the material studied the whole blood Cu content on feed 1 was 779 ± 395 fs-g/kg and on feed 2 749 ± 369 /ig/kg. The content trebled following the giving of the trace mineral mixture to 2044 ±1613 /