Abstract
ABSTRACTThe influence of supplemental tocopherol level (0, 250 and 500 IU RRR-α-tocopherol/d/steer) and injectable retinol form (retinyl propionate vs retinyl palmitate) on growth performance, carcass characteristics and plasma tocopherol and retinol concentrations were evaluated in 108 Holstein steers fed a steam flaked corn-based finishing diet during 314-d feeding period. There were no treatment interactions (P > 0.10). During the initial 112-d period, dietary supplemental tocopherol tended to increase ADG (linear, P = 0.07) and DMI (linear, P = 0.06). Overall 314-d ADG, DMI, gain efficiency and carcass characteristics were not affected (P > 0.10) by dietary supplemental tocopherol. Overall DMI tended to be greater (3%, P ≤ 0.10) for steers injected with retinyl palmitate vs retinyl propionate. It is concluded that vitamin E supplementation above basal requirements may enhance growth performance during the initial 112-d phase. However, the overall effect on growth performance and carcass characteristics was not appreciable. Injectable retinol ester form did not affect overall ADG, gain efficiency, or dietary NE. Based on plasma retinol concentrations, the bioavailability of retinyl palmitate is greater than that of retinyl propionate.
Highlights
Vitamin requirements (NASEM 2016) are influenced by intrinsic factors including age, weight, health and growth-performance, and by external factor including diet composition, and feed processing (McDowell 2000)
Performance trial to examine the effects of dietary supplemental vitamin E level and injectable retinol ester form on characteristics of growth performance, dietary energetics, carcass characteristics, and plasma tocopherol and retinol concentrations in calf-fed Holstein steers fed a conventional steamflaked corn-based growing-finishing diet
Treatments consisted of three levels of RRR-alpha-tocopherol supplementation (0, 250 and 500 IU /steer/d; EMCELLE, Stuart Products, Bedford, TX), and two injectable retinol ester forms
Summary
Vitamin requirements (NASEM 2016) are influenced by intrinsic factors including age, weight, health and growth-performance, and by external factor including diet composition (interactions with among dietary components), and feed processing (McDowell 2000). Vitamin A is typically supplemented to meet or exceed that requirement, regardless of the vitamin A equivalent content of the basal diet, per se (Vasconcelos and Galyean 2007). The basis for this practice is not certain, but may be related to the potential for extensive (70–80%) losses related to ruminal degradation (Rode et al 1990; Weiss et al 1995). The objective of the current experiment was to further evaluate feedlot growth performance and carcass characteristics of calf-fed Holstein steers as affected by dietary vitamin E supplementation as RRR α-tocopherol, and injectable vitamin A form (retinyl propionate vs retinyl palmitate)
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