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 Supplemental Zn (360 mg per day) was fed for four weeks, withdrawn for four weeks, and then resumed for another four weeks.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.

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 Supplemental vitamin E was fed for 28 d, withdrawn for 28 d, and then resumed for another 28 d. Blood was collected on d 1 before treatment administration, d 3, and biweekly thereafter.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.

Assessment of vitamin E nutritional status in sheep

The effects of supplemental dietary vitamin E (as DL-alpha-tocopheryl acetate; 0, 15, 30, and 60 IU/d) on serum, platelet, and muscle tocopherol and lipid (cholesterol and triglycerides) concentrations in 32 sheep were investigated in a 60-d trial. Serum, platelet, and muscle alpha-tocopherol concentrations increased linearly (P < .05) with treatment. Platelet tocopherol concentrations were more sensitive to vitamin E intake than either serum or muscle tocopherol. There were no effects on serum lipid concentrations. There were low correlations (P > .05) between serum or platelet tocopherol and either cholesterol or triglycerides or the sum of the two lipid fractions. Correlations between serum or platelet tocopherol and muscle tocopherol were also low (P > .05). Although platelet tocopherol was more sensitive to vitamin E intake than serum tocopherol, serum tocopherol concentrations can be reliably used to estimate vitamin E status. Expressing serum tocopherol relative to blood lipids did not improve the relationship between serum tocopherol and vitamin E intake.

Pre- and postpartum supplemental DL-alpha-tocopheryl acetate effects on placental and mammary vitamin E transfer in sheep

Twenty-six pregnant ewe lambs were used to study the effect of four treatment (T 1 to 4) levels of DL-alpha-tocopheryl acetate (0, 15, 30, and 60 IU.lamb-1.d-1) supplemented 28 d prepartum through 28 d postpartum on placental and mammary gland transfer of alpha-tocopherol. Blood samples were first obtained on d 28 prepartum and thereafter with milk samples at designated intervals up to 28 d postpartum for alpha-tocopherol analyses. Similarly, blood samples were obtained from neonatal lambs on d 1 before suckling and on d 3, 14, and 28 postpartum. Ewe lamb serum tocopherol concentrations averaged .66 micrograms/mL before T administration; 28 d later averages were .93, 1.94, 2.63, and 4.07 micrograms/mL (linear, P < .05) for T 1 to 4, respectively. Supplemental vitamin E had no effect (P > .05) on serum alpha-tocopherol of neonatal lambs, indicating inefficient placental transfer. By d 3, lamb serum tocopherol increased to 1.41, 1.84, 2.43, and 4.46 micrograms/mL (linear, P < .05) for T 1 to 4 following consumption of colostrum and declined to .46, .74, 1.10, and 1.68 micrograms/mL (linear, P < .05) by d 28. On d 1 there was a linear (P < .05) treatment effect on tocopherol in colostrum, with a low concentration of 3.30 micrograms/mL for the control (T 1) and a high of 9.55 micrograms/mL for T 4.(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)

Serum alpha-tocopherol concentration in sheep after intramuscular injection of DL-alpha-tocopherol

Forty-three crossbred wethers weighing 35 to 60 kg were used to investigate the effect of a single i.m. injection of DL-alpha-tocopherol (DL-alpha-ol). Animals were offered 1 kg/d of a basal diet containing 25 ppm of vitamin E. Lambs were randomly assigned to one of five DL-alpha-ol injection treatments as follows: 1) control (placebo, 0 IU), 2) 125 IU, 3) 250 IU, 4) 500 IU, or 5) 1,000 IU. Blood samples were taken via jugular venipuncture on d 1 before treatment administration and thereafter at designated intervals up to 360 h postinjection. The i.m. injections of DL-alpha-ol irrespective of dose increased serum alpha-tocopherol. Results showed a dose x time interaction (P less than .0001) across all treatments. Serum alpha-tocopherol increased rapidly to maximum concentration during the first 8 to 12 h for all non-zero treatments, followed by a rapid decline to pretreatment values. The mean serum alpha-tocopherol concentration at 0 h was .69 microgram/mL. Estimated peak serum alpha-tocopherol concentrations +/- SE were 6.68 +/- 1.04, 9.62 +/- 1.04, 21.66 +/- 2.37, and 50.75 +/- 7.05 micrograms/mL for Treatments 2 through 5, respectively. Results showed a quadratic dose effect (P less than .0003) on maximum response with apparently no effect on time taken to reach this peak. There was also a quadratic dose effect (P less than .0001) on the area under the concentration-time curve. The time taken for serum alpha-tocopherol to return to pretreatment levels increased with dose (56, 64, 67, and 74 h, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)