Long-term effects of feeding gossypol and vitamin E to dairy calves.

Male Holstein calves were used to test the effect of feeding 400 mg of free gossypol/kg of diet and to determine whether vitamin E could counteract gossypol toxicity. Fifty-two calves were allotted to treatments as follows: 1) soybean meal-based starter; 2) cottonseed meal-based starter; 3) cottonseed meal-based starter + 2000 IU of vitamin E/d per calf, and 4) cottonseed meal-based starter + 4000 IU of vitamin E/d per calf. Vitamin E supplementation (treatments 3 and 4) improved weight gain and feed intake over calves on treatment 1. Gossypol concentrations in plasma were higher in calves on treatments 2, 3, and 4 than in calves on treatment 1; however, no differences were observed among animals receiving the three cottonseed meal diets. Hemoglobin and hematocrit were decreased in calves receiving treatment 2, and vitamin E supplementation counteracted this effect (treatments 3 and 4). Plasma alpha-tocopherol concentrations were not affected by gossypol intake and followed the vitamin E supplementation pattern During the experimental period, 10 calves died, six from treatment 2 and two each from treatments 3 and 4. Necropsy findings from 4 of 10 calves were suggestive of gossypol toxicity. Histopathological examination revealed centrilobular necrosis in the liver and atrophy and vacuolation of cardiocytes. Feeding cottonseed meal caused death of some calves with gossypol related toxicity signs, but did not decrease plasma alpha-tocopherol; however, vitamin E supplementation increased performance and may have conferred some protection against gossypol toxicity.

Long-term effects of gossypol and vitamin E in the diets of dairy bulls.

Long-term effects of the inclusion of cottonseed meal in the diet on hematological and tissue parameters of Holstein bulls were investigated. Twenty-four Holstein bulls that were approximately 6 mo of age received the following treatments for 10 mo: 1) soybean meal plus 30 IU of vitamin E/kg, 2) cottonseed meal plus 30 IU of vitamin E/kg, and 3) cottonseed meal plus 4000 IU of vitamin E/d per bull. Treatments 2 and 3 were formulated to supply 14 mg of free gossypol/kg of body weight per d. Average daily gain, total gain, and final body weights were not affected by treatment. The osmotic fragility of erythrocytes was greater during all collection periods for bulls on treatments 2 and 3 than for bulls on treatment 1. The inclusion of 4000 IU of vitamin E/d per bull did not reduce the increase in the osmotic fragility of erythrocytes that was caused by gossypol. Bulls on treatment 3 had higher plasma alpha-tocopherol concentrations than did bulls on treatments 1 and 2. Vitamin E supplementation did not affect gossypol concentrations in plasma or tissue. The highest gossypol concentrations were found in the liver followed by the heart and testis. In vitro lipid peroxidation of tissue indicated that gossypol acts as an antioxidant in lipid peroxidation systems, and its role as an antioxidant may be dependent on dose or tissue. Cottonseed meal in the diets of bulls did not affect growth or vitamin E status.

Relative bioavailability of zinc methionine and two inorganic zinc sources fed to cattle.

A 12-week experiment was conducted to compare supplemental ZnMet, ZnSO4, and ZnO on Zn, Cu and metallothionein (MT) concentrations in various fluids and tissues of 32 yearling cattle. Supplemental Zn (360 mg per day) was fed for four weeks, withdrawn for four weeks, and then resumed for another four weeks. Mineral (Zn and Cu) concentrations were determined in serum, liver, pancreas, kidney, bone, bone marrow (metacarpus), hair, hoof and neck muscle (sterno mandibularis), and Zn only in erythrocytes, skin and cornea. Metallothionein levels were determined in liver, pancreas and kidney. There were no treatment differences (p > 0.05) in serum or erythrocyte Zn content for all days of collection. Serum Cu concentrations tended to decrease with all treatments. There were no treatment differences (p > 0.05) in Zn and Cu tissue concentrations and liver, kidney and pancreas MT concentrations. Tissue Cu concentrations did not drop in the supplemented treatments when compared to controls. At adequate levels of dietary Zn, bioavailability of supplemental Zn sources may be less important than under conditions of limited dietary Zn or if very high levels of supplemental Zn are fed.

Interaction of different organic and inorganic zinc and copper sources fed to rats.

A study was conducted to compare bioavailability, interactions and retention of different sources of Zn and Cu fed to rats. Sixty-three male CD rats were fed individually a purified diet and deionized water ad libitum. The nine treatments included were all combinations of three Zn (ZnMet, ZnLys, ZnSO4) and three Cu (CuLys, CuSO4, CuO) sources added to the basal diet at 30 mg/kg of Zn and 6 mg/kg of Cu forming a 3' 3 factorial experiment. After the four-week supplementation phase, four randomly selected rats from each treatment were sacrificed (Phase 1). The remaining rats were fed the purified, unsupplemented diet for an additional week (Phase 2) and then sacrificed. Mineral (Zn and Cu) concentrations were determined in plasma, liver, kidney, bone and muscle, and metallothionein (MT) content was determined in liver and kidney. Plasma Cu concentrations were lower (p < 0.05) for CuO-than CuSO4- and CuLys-supplemented rats. Bone Zn concentrations were higher (p < 0.05) for CuLys-than for CuO-supplemented rats. In all tissues where Cu was measured, CuO was the lowest (p < 0.05) available source of Cu. Furthermore, in muscle, CuSO4-supplemented rats had higher (p < 0.05) Cu concentrations than CuLys-supplemented rats. Kidney MT concentrations followed the same pattern as Cu concentrations, with CuO-fed rats having the lowest (p < 0.05) MT concentrations. Plasma Cu concentrations of depleted rats were lower (p < 0.05) for CuO-than CuLys-supplemented rats. Kidney Zn concentrations were lower (p < 0.05) for CuSO4-than for CuO-supplemented rats after depletion. In liver, CuO supplemented rats had the lowest (p < 0.05) Cu concentration. Copper oxide was less available than CuLys and CuSO4 when added in adequate dietary levels. However, organic (ZnMet and ZnLys) and inorganic (ZnSO4) sources of Zn were similar.

Assessment of vitamin E nutritional status in yearling beef heifers.

Effects of four dietary levels of DL-alpha-tocopheryl acetate (0, 500, 1,500, and 3,000 IU.animal-1.d-1) on serum, red blood cell (RBC), and tissue alpha-tocopherol concentrations were investigated in 32 yearling cattle during an 84-d trial. Supplemental vitamin E was fed for 28 d, withdrawn for 28 d, and then resumed for another 28 d. Blood was collected on d 1 before treatment administration, d 3, and biweekly thereafter. Serum alpha-tocopherol increased rapidly from pretreatment values (1.8 micrograms/mL) with linear (P < .05) treatment effects on d 3 and 14 and cubic treatment effects on d 28. Upon withdrawal of vitamin E supplementation, serum tocopherol concentrations declined and again increased rapidly and linearly by d 84 after supplementation was resumed. Concentration of alpha-tocopherol in RBC did not respond appreciably to supplemental vitamin E. There were no vitamin E treatment effects on blood lipid fractions (cholesterol and triglycerides). When serum tocopherol was expressed relative to the sum of cholesterol and triglycerides, response to vitamin E intake followed similar trends as serum alpha-tocopherol. The relationship between serum alpha-tocopherol concentrations or serum tocopherol:cholesterol plus triglycerides ratio and vitamin E intake was linear (P < .05) for d 14, 28, and 84 and linear with liver for d 84. Serum and liver tocopherol reflected vitamin E intake and can be used reliably to estimate vitamin E status in young cattle.

Relative bioavailability of two organic and two inorganic zinc sources fed to sheep.

A study was conducted to compare supplemental Zn lysine (ZnLys), Zn methionine (ZnMet), ZnSO4, and ZnO on Zn, Cu, and metallothionein (MT) concentrations in various fluids and tissues of 40 wether lambs. Supplemental Zn (360 mg/kg) was fed for 3 wk, withdrawn for 4 wk, and then resumed for another week. Mineral (Zn and Cu) concentrations were determined in serum, liver, pancreas, kidney, bone, bone marrow, hoof, and leg muscle, and only Zn was determined in skin and cornea. Metallothionein concentration was determined in liver, pancreas, and kidney. By d 49 serum Zn had increased less (P < .05) for controls than for all lambs except those fed ZnMet, and on d 55 it had increased more (P < .05) for ZnLys than for all but ZnSO4. There were no treatment effects in serum Cu concentration, but overall Cu concentration fell slightly for all treatments from d 0. The ZnLys-treated lambs had the highest (P < .05) Zn accumulation (581, 389, and 340 mg/kg) in kidney, liver, and pancreas, respectively. Both ZnSO4- and ZnMet-treated lambs had higher (P < .05) liver Zn concentrations (195 and 198 mg/kg, respectively) than the control lambs (127 mg/kg). Mean Zn concentration of bone, bone marrow, cornea, skin, hoof, and muscle was not different (P > .05) for lambs among treatments. The ZnLys-treated lambs had the highest (P < .05) MT concentrations (79, 167, and 68 micrograms MT/g for liver, kidney, and pancreas, respectively). Mean muscle Cu concentration was highest (P < .05) for controls (10 mg/kg).(ABSTRACT TRUNCATED AT 250 WORDS)

Serum and tissue tocopherol in sheep after intramuscular injection and(or) dietary vitamin E supplementation.

In a 28-d trial, 35 wethers weighing 35 to 60 kg were used to evaluate serum, liver, pancreas, kidney, diaphragm, heart, and neck muscle alpha-tocopherol concentrations after vitamin E administration as i.m. injections and(or) oral supplementation. Treatments (T) were as follows: 1) i.m. DL-alpha-tocopherol(DL-alpha-ol) d 1, 2) i.m. DL-alpha-tocopheryl acetate(DL-alpha-ac) d 1, 3) i.m. DL-alpha-ol d 1, 7, 14, and 21, 4) T 1 and oral supplementation, 5) T 3 and oral supplementation, 6) oral supplementation, and 7) control, no E supplementation. Supplemented wethers received 500 IU via injection and(or) 30 IU/kg of diet (acetate form). In a second 10-d trial, blood was periodically collected from 20 wethers weighing 32 to 47 kg that had been assigned to T as follows: 1) control, 2) i.m. DL-alpha-ol d 1, 3) i.m. DL-alpha-ac d 1, 4) T 2 d 1 and 7, and 5) T 3 d 1 and 7. Results from repeated measures ANOVA in both trials indicated that there were day x T effects (P < .0001) on serum alpha-tocopherol. Pretreatment serum tocopherol concentrations were .58 and .66 microgram/mL for Trials 1 and 2, respectively. In Trial 1, wethers receiving the four alcohol vitamin E forms showed a rapid increase in serum tocopherol between d 1 and 3, followed by a rapid decline to pretreatment concentrations for T 1, whereas T 3, 4, and 5 maintained higher than pretreatment concentrations after the decline.(ABSTRACT TRUNCATED AT 250 WORDS)