Evaluation of supplemental vitamin E on 56-day feedlot growth performance and plasma tocopherol concentrations in calf-fed Holstein steers

ABSTRACT

Fifty-four Holstein steer calves, divided in two weight groupings (141.2 ± 4.9 kg and 454.2 ± 7.0 kg respectively), were used in a 56-day study to evaluate the influence of supplemental vitamin E on growth performance and plasma vitamin concentrations. Steers were assigned within body weight groupings to 18 pens, 3 steers/pen. Dietary treatments consisted of a steam-flaked corn-based growing-finishing diet supplemented to provide 0, 250, or 500 IU/d of vitamin E as all racemic α-tocopherol. No morbidity was apparent during the course of the study. Calves in the heavier weight grouping had greater average daily gain (24.4%, P < .01), dry matter intake (54.3%, P < .01), and lower gain efficiency (40.7%, P < .01). Vitamin E supplementation did not affect (P > .10) feedlot growth performance. Initial and 56-day plasma tocopherol were not influenced (P > .10) by weight grouping. Final 56-day plasma tocopherol increased linearly (P < .01) with level of vitamin E supplementation. Plasma tocopherol of non-supplemented steers decreased (P = .01) from an average initial concentration of 1.66–1.16 ug/mL at day 56. It is concluded that vitamin E supplementation of calf-fed Holstein steers receiving a conventional steam-flaked corn-based growing-finishing diet is not expected to enhance growth performance.

KEYWORDS:

• Tocopherol
• Holstein
• feedlot
• performance

1. Introduction

The effect of vitamin E supplementation of feedlot cattle on growth performance has not been consistent. Numerous studies (Arnold et al. 1992; Zinn et al. 1996; Rivera et al. 2002; Carter et al. 2005; Montgomery et al. 2005) have failed to show a growth performance response to supplemental vitamin E. In other instances, vitamin E supplementation enhanced daily body weight (BW) gain (Reddy et al. 1987; Pehrson et al. 1991; Burken et al. 2012). Inconsistencies in growth performance responses may be attributable to previous nutritional status, including vitamin E status, dietary vitamin E intake, and animal stress. Apart from growth performance affects, per se, vitamin E supplementation may enhance immunocompetence (Rivera et al. 2002) and carcass characteristics (Rivera et al. 2002; Montgomery et al. 2005) or meat quality as related to colour stability (Arnold et al. 1992, 1993).

The objective of the present study was to evaluate vitamin E supplementation of calf-fed Holstein steers at two feedlot phases representative of the early growing and later finishing periods.

2. Materials and methods

All animal care, handling, and sample techniques followed protocols approved by the University of California, Davis, Animal Use and Care Committee.

2.1. Experimental location

This trial was conducted at the Desert Research Center of the University of California Davis, during the period of May 13 through and 8 July 2014 (56-day feeding trial). The Desert Research Center is located in the Imperial Valley, California (32°47′31″N and 115°33′47″W). It is about 16 m below sea level, and under Sonoran desert conditions (BWh classification according to Köppen). This region is characterized as dry and arid with extreme temperatures in summer (≥42°C), and an average annual precipitation of 85 mm.

2.2. Weather measurement and temperature humidity index (THI) estimation

Climatic variables (ambient temperature, relative humidity, solar radiation, black globe temperature, and wind speed) were obtained every 30 min from an on-site weather station (University of California Agriculture Field station) throughout the experimental period. The temperature humidity index was calculated using the following formula: THI = 0.81 × T + RH (T – 14.40) + 46.40 (Hahn 1999).

2.3. Animal management

Fifty-four Holstein steer calves divided into two groups, light and heavy (initial BW = 141.2 ± 4.9 kg and BW = 454.2 ± 7.0 kg, respectively), were used in a 56-day experiment to evaluate the influence of supplemental vitamin E on growth performance and plasma vitamin concentrations.

Steers were assigned within BW groupings to 12 pens, 3 steers/pen. Pens were 5.5 × 9.1 m with 27 m² of shade and were equipped with automatic waterers and fence-line feed bunks (4.3-m long). Steers in the heavy grouping were implanted with Revalor-S (Intervet Inc., Millsboro, DE) 35 day prior to initiation of this study. For calculating steer performance, initial and final BWs were reduced 4% to account for digestive tract fill.

2.4. Treatments

Dietary treatments consisted of a steam-flaked, corn-based, growing-finishing diet (Table 1) supplemented to provide 0, 250, or 500 IU/d of vitamin E as all racemic (RRR) α-tocopherol (Emcelle Tocopherol; 500 I.U. d-alpha-tocopherol/mL; Stuart Products). Based on diet formulation, the basal diet contained 21 I.U. tocopherol/kg (DM basis). Steers were provided ad libitum access to the experimental diets. Fresh feed was provided twice daily (0600 and 1400 h). Daily application of vitamin treatments was accomplished by dilution in 30 mL of water before top dressing onto feed provided in the 0600 h feeding. On day 1 and 56, blood samples were collected from one steer per pen via jugular puncture into heparinized tubes. Subsequently, the blood was centrifuged at 1070 × g for 10 min. Plasma α-tocopherol analysis was conducted by the Veterinary Diagnostic Laboratory (College of Veterinary Medicine, Iowa State University, Ames, IA 50011) according to procedures described by Stahr (1991).

Table 1. Composition of basal diet fed to steers.

Item	Basal diet % DM
Steam-flaked corn	67.31
DDGS	10.00
Sudangrass hay	12.00
Molasses cane	4.00
Yellow grease	3.00
Urea	1.26
Dicalcium phosphate	0.33
Limestone	1.63
Magnesium oxide	0.15
Trace mineral salt^a	0.30
Rumensin 90, g/ton	150
Nutrient Composition^b
NE, Mcal/kg
Maintenance	2.21
Gain	1.54
Crude protein, %	14.0
Calcium, %	0.79
Phosphorus, %	0.34
Potassium, %	0.75
Magnesium, %	0.29
Sulphur, %	0.16
Vitamin E, IUkg	21.4

Note: DDGS, distillers dried grains plus solubles; NE, net energy.

^aTrace mineral salt contained: CoSO₄, .068%; CuSO₄ , 1.04%; FeSO₄ , 3.57%; ZnO, 1.24%; MnSO₄ , 1.07%; KI, .052%; and NaCl, 92.96%.

^bBased on tabular values for individual feed ingredients (NRC 2000).

2.5. Statistical analyses

The experimental data were analysed as a completely randomized design with a 2 × 3 factorial arrangement of treatments according to the statistical model Y_ij = μ + B_i + T_j + (BT)ij + ε_ij, where μ is the common experimental effect; B_i represents weight groups (df = 1), T_j represents supplemental vitamin E effect (df = 2), (BT)ij represents interaction between main effects (df = 2), and ε_ij represents the residual error (df = 12). Treatments effects were tested by polynomial contrasts. Analysis was performed using Statistix-10 (Analytical Software, Tallahassee, FL). The experimental unit was the pen. Contrasts were considered significant when the P-value was ≤.05, and tendencies were identified when the P-value was ≤10.

3. Results and discussion

Average ambient air temperature, relative humidity, and THI during the course of the study were 33.3°C, 48%, and 82.3, respectively. Total precipitation was 1.02 mm.

The effect of live weight and supplemental vitamin E on growth performance is shown in Table 2. Vitamin E supplementation of Holstein steers was evaluated at two initial weight grouping (141 vs. 454 kg). As expected, calves in the heavier weight grouping had greater average daily gain (ADG) (24.4%, P < .01), dry matter intake (DMI) (54.3%, P < .01), and lower gain efficiency (40.7%, P < .01). A similar response on growth performance of feedlot Holstein steers in different BWs is reported by Salinas Chavira et al. (2009).

Table 2. Influence of live weight and vitamin E supplementation on growth performance and plasma tocopherol.

							P values
	Weight group		Vit E, UI / hd / d				Weight	Vitamin E
Item	Light	Heavy	0	250	500	SEM	group	Linear	Quadratic
No. of pens	12	6	6	6	6
Live BW, Kg1
Day 1	141.3	454.2	299.2	295.6	298.5	7.0	<.01	.95	.71
Day 56	210.7	546.4	381.9	376.6	377.2	6.6	<.01	.62	.72
ADG, Kg/d	1.24	1.64	1.48	1.45	1.40	0.05	<.01	.31	.93
DMI, Kg/d	4.59	10.05	7.37	7.37	7.21	0.16	<.01	.48	.68
ADG/DMI	0.271	0.164	0.219	0.217	0.217	0.01	<.01	.89	.92
Plasma tocopherol, μG/mL
Day 1	1.62	1.47	1.60	1.50	1.54	0.12	.30	.72	.65
Day 56	2.13	2.35	1.21	2.40	3.11	0.20	.40	<.01	.36

Consistent with previous studies involving corn-based growing-finishing diets fed to Holstein steers (Arnold et al. 1992; Garber et al. 1996), vitamin E supplementation did not influence (P > .10) feedlot growth performance. Likewise, vitamin E supplementation at levels up to 500 IU/d did not enhance feedlot growth performance of beef breeds (Rivera et al. 2002; Burken et al. 2012). Health status may be a factor in short-term responses to vitamin E supplementation. Rivera et al. (2002) observed that 14-day ADG was enhanced in newly received calves infected with infectious bovine rhinotracheitis virus (IBR). However, in a second trial in which newly received calves were not infected with IBR, vitamin E supplementation did not influence growth performance during a 28-day receiving period. No morbidity was detected among cattle during the course of the present study.

Initial and 56-day plasma tocopherol were not influenced (P > .10) by weight grouping, averaging 1.57 and 2.21 ug/mL, respectively. Consistent with previous studies, plasma tocopherol increased linearly (P < .01) with the level of vitamin E supplementation (Arnold et al. 1992; Garber et al. 1996; Velasquez-Pereira et al. 2002; Yang et al. 2002; Carter et al. 2005; Cusack et al. 2005; Salinas-Chavira et al. 2014). The source of supplemental vitamin E used in this study was RRR-alpha-tocopherol. This is a ‘natural’ source of vitamin E derived from vegetable oils, primarily soybean, canola, and sunflower oils. This natural form of vitamin E is stipulated as d-alpha-tocopherol or, more correctly, RRR-alpha-tocopherol. To enhance stability in diet preparations, the RRR-alpha-tocopherol is converted to RRR-alpha-tocopheryl acetate. It was daily administered in feed and enhanced plasma tocopherol levels; further research is needed for stability of both sources of vitamin E when administered in feed with longer storage duration. Based on plasma tocopherol levels, the ester form dose did not reduce bioavailability of RRR-alpha-tocopherol (Hidiroglou et al. 1988, 1992). Likewise, Salinas-Chavira et al. (2014) observed similar increases in plasma tocopherol whether the vitamin was supplemented as RRR-alpha-tocopheryl acetate or as all-rac α-tocopheryl acetate (a racemic mixture of 8 tocopherol sterioisomers).

For non-supplemented steers, plasma tocopherol decreased (P = .01) from an average initial concentration of 1.66 ug/mL to 1.16 ug/mL at day 56. Likewise, Carter et al. (2005) observed a decline in plasma tocopherol during a 28-day study in non-supplemented cattle fed a whole shelled corn-based diet. Nevertheless, failure to observe a growth performance response is consistent with the generalization that ADG response to vitamin E supplementation is not expected unless plasma tocopherol levels are less than 1 μg/mL (Reddy et al. 1987; Pehrson et al. 1991).

4. Conclusion

Vitamin E supplementation of calf-fed Holstein steers receiving a conventional steam-flaked corn-based growing-finishing diet is not expected to enhance their feedlot growth performance.

Disclosure statement

No potential conflict of interest was reported by the authors.