Ruminants: Vitamin E

A. General Considerations
The two primary reasons for fortification of ruminant diets with supplemental vitamin E are to prevent frank or marginal deficiency and to optimize animal performance. The levels required to optimize performance are, in most cases, considerably higher than those needed to prevent deficiency symptoms. When the value obtained through feeding higher levels of vitamin E outweighs the cost, the higher level of supplementation becomes a sound nutritional management practice.

Factors of primary importance in determining vitamin E supplementation include:

• vitamin E levels in the basal diet;
• selenium levels in soils and feedstuffs;
• selenium availability to the animal, which is reduced by high sulfate or calcium levels in feed or water;
• presence of compounds in the diet that increase selenium and vitamin E requirements, (i.e., heavy metals, unsaturated fats, nitrates, mycotoxins);
• excessively dry or poor quality ranges or pastures for grazing livestock;
• harvesting, drying or storage conditions of forages that destroy vitamin E;
• accelerated rates of gain or milk production;
• intensified, confinement production systems that increase overall stress load; and
• disease exposure (McDowell, 1992, 2000; McDowell and Williams, 1991).

To protect against loss of vitamin E activity during processing and storage, feeds should be fortified using alpha-tocopheryl acetate, the most stable source of vitamin E activity available for feed use. Methods of providing supplemental vitamin E are: (a) in dry feeds, mineral supplements or liquid supplements, (b) in drinking water and (c) parentally as intramuscular injection.

Dispersible liquid concentrates of vitamin E are available for liquid feeds and water supplementation. Parental vitamin E is usually given as an intramuscular injection in an oil base for highest absorption (Machlin, 1991). Combination products containing vitamin E and selenium are often given intramuscularly to animals exhibiting clinical signs of muscular degeneration, or prophylactically, just prior to or just after stress, as in dairy cows prior to calving or receiving cattle upon arrival at the feedlot.

B. Dairy Calves
Based on a series of studies, Reddy et al., (1987a) concluded that the addition of 125 to 250 IU of vitamin E per head per day to conventional dairy calf diets optimized calf performance through 24 weeks of age (Fig. 1). The same authors recommended that cattle from six to 12 months of age receive 200 to 400 IU vitamin E daily, depending on previous dietary history in relation to vitamin E and selenium. Luhman et al. (1993) conducted two experiments with calves from birth to four weeks of age, and fed either 20 or 100 IU vitamin E per day in milk replacer. Calves fed 100 IU vitamin E per day gained 8% to 13% more weight and had fewer scour days than calves supplemented with 20 IU per day vitamin E ( Fig. 2). A more recent study from the same research group (Johnson et al., 1997) compared feeding either 100 or 200 IU vitamin E daily in milk replacer to Holstein bull calves from 0 to 28 days of age. Although weight gain and feed efficiency were similar between the two groups, calves fed 200 IU vitamin E had numerically fewer scour days (2.9 versus 3.8) and lower medication costs ($4.46 versus $5.29) than calves fed 100 IU vitamin E daily ( Fig. 3). Based on these results, the optimum level of supplemental vitamin E in calf diets appears to be 100 to 200 IU per day. Both milk replacers and calf starter feeds should be fortified to provide these levels of vitamin E in order to ensure optimum vitamin E intakes from early life through weaning and into the early phases of postweaning growth.

Cellular effects of vitamin E supplementation in calves include: 1) maintenance of cell membrane stability, as evidenced by lower activity of certain cytoplasmic enzymes in serum (Cipriano et al., 1982; Hidiroglou et al., 1973; Lynch, 1983; Reddy et al., 1985a); 2) decreased serum cortisol concentrations (Reddy et al., 1987b); and 3) potentiation of the immune system (Cipriano et al., 1982; Reddy et al., 1986; Hidiroglou et al., 1992; Eicher-Pruiett et al., 1992; Eicher et al., 1994). A University of Florida study (Velásquez-Pereira et al., 1999) tested the effects of supplemental vitamin E on young dairy calves fed gossypol. Calves were started at either two or four weeks of age and fed starters containing either soybean meal or cottonseed meal for one to two months. All calf starters contained 30 IU per kg supplemental vitamin E. Calves fed cottonseed meal received an additional 0, 2,000 or 4,000 IU per day vitamin E either through milk replacer (calves started at two weeks of age) or calf starter. Supplemental vitamin E reversed several indices of gossypol toxicity and increased overall growth performance compared to unsupplemented calves. Calf mortality was 0 percent for the soybean meal treatment and 20.7, 9.1 and 8.7 percent for the cottonseed meal treatment groups with 0, 2,000 or 4,000 IU vitamin E per day, respectively.

C. Dairy Heifers
There is little data on vitamin E supplementation of dairy heifers beyond the young-calf stage of development. Reddy et al. (1987a) suggested that dairy cattle six to 12 months of age be supplied with 200 to 400 IU vitamin E per head per day. Cattle of this age range are often kept on pasture during part of the year. Good quality pasture contains ample vitamin E, but pasture quality often declines markedly during summer and fall, during which time supplementation may be needed. Ohio State research (Hogan et al., 1992) showed that increased vitamin E supplementation prepartum reduced the incidence of mastitis in dairy heifers. Data from beef cattle, discussed later in this section, indicate that feeding 400 to 500 IU per day vitamin E results in improved overall performance during stress periods, such as handling and shipping. Supplemental vitamin E has been shown to increase pregnancy rate in beef heifers (LaFlamme and Hidiroglou, 1991). Based on the available data, vitamin E supplementation (1,000 IU per day) is warranted for dairy heifers during the last four to six weeks prior to first calving, and may be beneficial at 400 to 500 IU per day during periods of high stress such as shipping, regrouping or mass vaccination.

Beneficial effects of supplemental vitamin E, in conjunction with adequate dietary selenium, for dairy cows include: 1) reduced incidence of reproductive disorders (Harrison et al., 1984; Miller et al., 1997); 2) reduced clinical mastitis and somatic cell count (Smith et al., 1997; Weiss, 1998); 3) protection of milk from oxidation (King, 1968; Charmley and Nicholson, 1994; Focant et al., 1998). These findings support the concept that optimal vitamin E supplementation for a dairy cow is 1,000 IU per day during the dry period and 500 IU per day during lactation for optimum reproduction and udder health.

Feeding supplemental vitamin E at levels of 1,000 to 2,000 mg of naturally occurring mixed tocopherols per cow per day increased the vitamin E content of milk and its stability against oxidized flavor (Krukovsky and Loosli, 1952; Neilsen et al., 1953). The vitamin E content of milk from cows fed stored feeds was lower than that of milk from cows on pasture and their milk was more susceptible to development of oxidized flavor (Krukovsky et al., 1950). Feeding supplemental vitamin E as dl-alpha-tocopheryl acetate, providing an equivalent of 500 IU per cow per day, increased the vitamin E content and oxidative stability of milk (Dunkley et al., 1967). Nicholson et al. (1991) provided evidence that adequate selenium status improves the transfer of dietary tocopherol to milk. Higher levels of vitamin E (9,000 IU per day) are required to prevent milk oxidation and off-flavor caused by unsaturated lipids in the diet or other factors, such as high dietary copper (Focant et al., 1998; Charmley and Nicholson, 1994).

More recent studies have shown that vitamin E levels higher than 1,000 IU per day may be optimal during the late dry period and early lactation, the time when the highest rate of new intramammary infections occur. Feeding 4,000 IU of vitamin E for 14 days prepartum, followed by 2,000 IU per day for 30 days postpartum, resulted in a significant reduction in new mammary infections and clinical mastitis compared to levels of 1,000 IU and 500 IU per day vitamin E during the same periods (Weiss et al., 1997) (Fig. 4). Both groups were fed 1,000 IU vitamin E per day for the first 46 days of the dry period. Dietary selenium concentration was 0.15 ppm (dry matter), and plasma selenium concentrations (>50 ng/ml) were within the adequate range. Politis et al. (1995,1996) provided evidence that feeding 3,000 IU per day of supplemental vitamin E, in diets containing 0.3 ppm selenium, for 28 days prior to calving and continuing for 56 days after calving significantly improved neutrophil and macrophage function and reduced somatic cell count in dairy cows (Fig. 5, 6).

Treated cows also received a single intramuscular injection of 5,000 IU vitamin E seven days prior to expected calving date. Plasma selenium levels were 86 to 90 ng/ml. The higher level of vitamin E supplementation maintained plasma vitamin E levels above the 3.0 µg/ml threshold identified by Weiss et al. (1997) as minimal for optimum udder health in dairy cows.

The authors concluded that supplementing the higher level of vitamin E (3,000 IU per day for 84 days) prevented suppression of white blood cell function during the parturient period (Politis et al., 1995). Based on these data, it has been suggested that 2,000 IU vitamin E per day may be optimal during the late dry period and early lactation (Goff and Horst, 1998).

Assessing vitamin E status of dairy cows has been discussed recently by Weiss (1998). Plasma levels of 3.0 to 3.5 µg/ml are suggested as minimal for optimal neutrophil function and reduction of clinical mastitis. A study of 50 U.S. dairy herds (Miller et al., 1995) reported a mean plasma vitamin E value of 2.55 µg/ml, with significantly higher levels in summer and fall (June through November) than in winter and spring (December through May), which reflects forage quality in the months preceding each period. An epidemiological study of Holstein cows (Barnouin and Chassagne, 1998) identified vitamin A, D and E supplementation during the dry period as the most discriminating factor associated with a reduced incidence of clinical mastitis. Politis et al., (1995) reported that 3,000 IU of vitamin E per day were required to maintain plasma vitamin E above 3.0 µg/ml at parturition. Given these findings, and those discussed earlier, levels of vitamin E greater than 1,000 IU per day may be economically justified during the last 28 days of the dry period and the first four to eight weeks of lactation.

E. Breeding Bulls
Effects of supplemental vitamin E above minimum requirements on breeding performance of dairy or beef bulls are largely unknown. A recent, long-term study of gossypol toxicity in dairy bulls (Velásquez-Pereira et al., 1998a) found that feeding bulls 4,000 IU per day of supplemental vitamin E reversed the negative effects of gossypol on several reproductive parameters, compared to bulls fed gossypol plus approximately 240 IU per day. Compared to the soybean meal-based control diet (average vitamin E intake of 240 IU per day), bulls fed gossypol plus 4,000 IU of vitamin E per day had numerically higher sperm production, earlier age at puberty and higher plasma testosterone, suggesting that vitamin E supplementation may exert positive effects on male reproduction in cattle. However, this has not yet been rigorously tested experimentally.

Recent studies have examined the benefits of feeding supplemental vitamin E to beef brood cows during the last trimester of pregnancy. Zobell et al. (1995) conducted a trial using 134 crossbred beef cows during the last 60 to 100 days of gestation. Treatment groups were balanced by age, weight, breed, sire and body condition. The control group was fed 80 IU per day vitamin E and the treatment group 1,000 IU per day supplemental vitamin E. Feeding 1,000 IU per day vitamin E significantly increased vitamin E concentrations in the plasma of both cows and calves, increased vitamin E in colostrum, numerically increased plasma immunoglobulin G (IgG) concentration of calves and significantly reduced the incidence of calf scours ( Fig. 7, 8). In this study, spring-calving beef cows fed 1,000 IU of vitamin E per day conveyed improved vitamin E status and health status to their calves compared to cows fed 80 IU of supplemental vitamin E daily.

Bass et al. (1996) conducted two experiments using 90 beef cows calving in late winter and 42 cows calving in early fall. Cows were allotted to treatment groups by breed, age and initial serum vitamin E concentration. All cows were fed a free-choice complete vitamin-mineral mix, with the treatment group receiving either 1,000 IU per day (winter-calving) or 600 IU per day (fall-calving) of supplemental vitamin E mixed with the free-choice supplement. Vitamin E was provided starting one month before the start of the 65-day calving season and continued until calving. In the winter-calving cows, feeding 1,000 IU per day of supplemental vitamin E significantly increased serum vitamin E levels in cows and calves, serum IgG levels of calves and average daily gain (ADG) of calves measured from birth to weaning (average of 204 days) ( Fig. 9, 10, 11).

This study indicates that cows calving in winter/spring benefited from 1,000 IU per day of supplemental vitamin E. Cows calving in early fall and supplemented with 600 IU per day of vitamin E exhibited similar levels of serum and colostrol vitamin E and similar average daily gains for calves. Fall-calving cows were expected to have higher vitamin E status due to recent grazing of pasture and as a result, were supplemented with less vitamin E. However, serum vitamin E levels were similar to those in the first study. Several factors may explain the smaller response to supplemental vitamin E in this group, including better tissue vitamin E status due to grazing pasture, the lower level of vitamin E supplementation or fewer cows per treatment. Overall, the results confirm those of Zobell et al. (1995) that winter- and spring-calving beef cows and their calves benefit from 1,000 IU per day of supplemental vitamin E during the last 60 to 90 days of gestation. The response of fall-calving cows to vitamin E supplementation will depend on the quality and quantity of pasture available during gestation.

A study of pregnant beef heifers (Coalson et al., 1997) found no significant effect of supplemental vitamin E (1,000 IU per day, fed for 50 days precalving) on calf immune status or breeding performance after calving. However, the vitamin E concentration in serum and colostrum were not affected by treatment, leaving open the question of actual intake of supplements by heifers in the study. Feeding beef calves 500 IU per day of supplemental vitamin E starting at 165 days of age tended to increase rate of gain of calves in one of two experiments (Wright et al., 1997). The response of growing calves to vitamin E will likely depend on pasture and forage quality and exposure to stress.

Based on available data, the optimal level of vitamin E supplementation of winter- and spring-calving beef cattle appears to be 1,000 IU per day. The rationale for supplementing fall-calving cows and growing beef calves is open to interpretation by the nutritionist, veterinarian and producer, in consideration of pasture and forage quality and overall stress level of the cattle.

An excellent compilation of research trials on the effects of supplemental vitamin E on receiving and feedlot cattle has been published by Secrist et al. (1997). A summary of five trials involving transport-stressed receiving cattle (average body weight of 550 lbs, or 250 kg) found that supplemental vitamin E at 400 to 1,400 IU daily tended to increase average daily gain (ADG) and improved feed efficiency when fed for the first 28 days after shipment. Morbidity was numerically less for the vitamin E supplemented animals.

In a series of 28-day feedlot receiving trials, Lee et al. (1985) observed an improvement in early performance of newly arrived growing cattle supplemented with 450 IU of vitamin E (as dl-alpha-tocopheryl acetate) per head per day that were stressed by long distance shipment and changes from green forages to high grain feedlot diets.

Gill et al. (1986) supplemented newly received feedlot cattle with 1,600 IU vitamin E (as dl-alpha-tocopheryl acetate) per head per day for the first 21 days and 800 IU vitamin E for the remaining seven days of a 28-day trial. Average daily gain and gain-to-feed ratios were improved by 23.2% and 28.6%, respectively, for vitamin E-supplemented stressed cattle (Table 1). The number of sick pen days per head was reduced by 15.6%, and morbidity was reduced by 13.4% by vitamin E supplementation.

The NRC (1996) beef cattle publication recommends feeding 400 to 500 IU of vitamin E per day during the receiving and starting period. Based on available data, optimal vitamin E levels for receiving cattle appear to fall in the range of 500 to 1,400 IU per day, depending on stress load and previous nutritional history (Table 2). Cattle received from grazing good quality pasture will have higher vitamin E status.

A summary and analysis of 21 controlled beef feedlot studies (Secrist et al., 1997) (Fig. 12) on the effects of feeding supplemental vitamin E revealed an overall significant improvement in ADG and feed efficiency in cattle supplemented with vitamin E (200 to 2,000 IU daily) during the finishing period (38 – 298 days). In most of the studies, cattle were on feed for 84 to 145 days and fed 85% to 90% concentrate. The authors concluded that supplementing 500 IU of vitamin E daily during the finishing period may be justified based on improved cattle performance alone, although these levels are also adequate to significantly improve the retail value of beef based on visual appearance (Faustman et al., 1998).

Color is an extremely critical component of fresh red meat appearance and greatly influences the customer's perception of meat quality. Discoloration of meat results in retail price discounts and early discards from meat case display (Smith et al., 1997; Liu et al., 1995). The cost of discounting or discarding meat prior to its normal expiration date is high. Many attempts have been made to control lipid oxidation in meats through the use of antioxidants. The most successful approach is through dietary supplementation of vitamin E, which functions as a lipid-soluble antioxidant in cell membranes (Linder, 1985), thus protecting phospholipids and even cholesterol against oxidation. Increased dietary levels of vitamin E result in higher tissue levels of alpha-tocopherol and greater oxidative stability of these tissues. Faustman et al. (1998) observed that increasing tissue levels of alpha-tocopherol by supplementing finishing cattle with 500 IU of vitamin E daily stabilized and reduced oxidation of muscle myoglobin, thus preserving the cherry-red color of beef. Dramatic effects (Illus. 1) of vitamin E supplementation (500 IU per head daily) to finishing steers on the stability of beef color have been observed (Faustman et al., 1989a). Loin steaks of control steers discolored two to three days sooner than those supplemented with vitamin E. Supplemental dietary vitamin E extended the color shelf life loin steaks from 3.7 to 6.3 days. The alpha-tocopherol content of loin tissue of the supplemented animals was approximately four times greater than controls (Faustman et al., 1989a). Vitamin E supplementation of finishing steers increased the stability of beef color in several other studies (Arnold et al., 1993; Arnold et al., 1992; Hill et al., 1992, 1989; Schaefer et al., 1991). Vitamin E also plays a role in controlling the color of veal calf meat. Combined feeding of monosodium phosphate and 100 IU of vitamin E per calf daily produced a light colored veal without producing anemia (Agboola et al., 1990). These results are consistent with the role of vitamin E as primary biological antioxidant of cellular membranes.

More recently, feeding 1,000 or 2,000 IU of supplemental vitamin E daily for the last 100 days of the finishing period was found to improve color retention of ground beef (Cabedo et al., 1998). Crossbred (Angus x Hereford x Salers) cattle were brought from grass pasture to the feedlot for the 100-day finishing trial. Growth of bacterial populations on ground beef was not influenced by supplemental vitamin E.

Sherbeck et al. (1995) reported that meat from steers fed 500 IU per day of vitamin E for 123 days prior to slaughter had significantly better color retention and less lipid oxidation than meat from unsupplemented cattle. Wulf et al. (1995) found improved appearance and extended caselife of meat harvested from lambs fed 500 IU of supplemental vitamin E daily for a 56-day feeding period.

Sanders et al. (1997) studied the effects of feeding 0, 1,000 or 2,000 IU of vitamin E daily for 100 days prior to slaughter in beef for the Japanese export market. Meat from cattle fed supplemental vitamin E during the finishing period displayed significantly superior lean color, less discoloration, less lipid oxidation and more desirable overall appearance. Steaks from vitamin E-fed cattle were preferred by 91% of 10,941 Japanese survey participants. This study clearly demonstrated the benefit of increased vitamin E supplementation to the export value of beef, as well as confirming the results of previous studies.

A large project evaluated the effect of supplementing 500 IU of vitamin E daily to 235,000 feedlot cattle for the last 100 days of the finishing period on retail beef caselife in four retail grocery store chains (Westcott et al., 1997). Meat from vitamin E- supplemented cattle had a significant increase in display life and reduced discounts compared to meat from control cattle.

The net economic retail value of beef harvested from cattle fed 500 to 1,000 IU of vitamin E daily for 100 days prior to slaughter is $20 to $60 (U.S.), with an average value of approximately $30 per carcass (Smith et al., 1997). The normal cost of vitamin E supplementation is $1.50 to $3.00 per head for 100 days of supplementation. This significant increase in retail value and consumer appeal of the final product, along with improved animal performance from feeding 500 IU per day or more vitamin E to finishing cattle (Secrist et al., 1997), provides a strong rationale for supplementation of vitamin E at 500 to 1000 IU per day in beef-cattle finishing rations.

J. Sheep and Goats
Lamb mortality was decreased by 50% when ewes were supplemented with 330 IU per day vitamin E for the last 21 days prior to lambing (Thomas et al., 1995). Total lamb production per ewe was 2.3 kg higher for vitamin E-supplemented ewes. In a subsequent study (Kott et al., 1998), 1,302 ewes were used in a three-year study in which ewes were supplemented with either 0 or 330 IU per day of vitamin E during the last 21 days prior to lambing. Lamb mortality was reduced significantly, from 17% to 12%, in early-lambing ewes fed 330 IU of vitamin E daily. Effects of vitamin E were not significant for late-lambing ewes, probably due to their access to good quality pasture.

Williamson et al. (1995) reported that injecting ewes with 4,800 IU of vitamin E two weeks prior to lambing and again at lambing significantly improved lamb vigor and increased average daily gain of lambs through weaning. Daniels et al. (1998) tested effects of oral vitamin E supplementation in 580 twin lambs. Lambs were administered either no vitamin E, a single oral dose of 391 IU vitamin E within six hours of birth, or two oral doses of 391 IU vitamin E at six hours after birth and between 10 and 18 hours after birth. Body weight of male lambs given two doses of vitamin E was greater than control at 120 days. Death loss was lowest for male lambs given two oral doses of vitamin E.

Dairy ewes given two subcutaneous injections of a vitamin E–selenium preparation (5 mg and 0.1 mg per kg body weight) during the dry period had significantly lower somatic cell counts and increased neutrophil activity compared to controls (Morgante et al., 1999). Incidence of clinical mastitis (4% versus 6%) and intramammary infection (9% versus 11.3%) were numerically but not significantly lower for the vitamin E treatment.

Available data indicate that gestating ewes fed stored forages or poor quality pasture should be supplemented with vitamin E at the rate of 330 IU per day in order to reduce lamb mortality and increase lamb weight at weaning. To date, intermediate levels of supplementation have not been tested.

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