Subcutaneous fatty acid composition of steers finished as weanlings or yearlings with and without growth promotants

Cletos Mapiye,Vern S Baron,John A Basarab,Tyler D Turner,Michael Er Dugan,Jennifer L Aalhus

doi:10.1186/2049-1891-4-41

Abstract

BackgroundThe current study evaluated the subcutaneous fatty acid (FA) composition of calf- and yearling-fed steers with or without growth promoting implants. Crossbred steers (n = 112; 267 ± 5.0 kg) of the same contemporary group were allocated to one of four production system and implant strategy based treatments in a completely randomized design with a 2 × 2 factorial arrangement of treatments.ResultsThere were no interactions (P > 0.05) between production systems and growth promoting implants for the total and individual subcutaneous FA. Yearling as opposed to calf finishing reduced (P < 0.05) subcutaneous proportions of C20:3n-6, trans (t)12-18:1, C14:0, several minor cis-monounsaturated FA (c-MUFA; c9-14:1, c11-16:1, c11-18:1, c12-18:1, c13-18:1, c9-20:1 and c11-20:1), and increased (P < 0 .05) subcutaneous proportions of t11c15-18:2, total and individual branched-chain FA. Subcutaneous fat from steers implanted with growth promotants had higher (P < 0.05) proportions of total polyunsaturated FA (PUFA), total n-6 PUFA, C18:2n-6 and individual t-18:1 isomers (t6 to t10) compared to non-implanted steers.ConclusionsOverall, current findings show that production systems and growth promotants led to only minor differences in subcutaneous FA composition of beef steers.

Highlights

The current study evaluated the subcutaneous fatty acid (FA) composition of calf- and yearling-fed steers with or without growth promoting implants
Nutritional composition of the experimental diets and steers subcutaneous fat thickness Overall, the nutritional composition of the finisher diets were similar (Table 1), except that calcium was slighlty higher for the yearling-fed steers compared to calf- fed steers
Total FA content and FA composition of the finishing diets were similar (Table 1) with the diet fed to yearling-finished steers having slightly more linoleic acid (C18:2n-6, LA) than that fed to calf-finished steers

Summary

Introduction

The current study evaluated the subcutaneous fatty acid (FA) composition of calf- and yearling-fed steers with or without growth promoting implants. It has been suggested that cattle entering a Growth promoting implants characterised as being estrogenic (e.g., estradiol benzoate and estradiol) or androgenic (e.g., trenbolone acetate and progesterone) are used extensively in calf and yearling production systems to increase growth rates, carcass yield [3,7] and to reduce carcass fatness [8,9]. Regarding FA composition, studies with estrogen- or androgen-implanted steers showed small increases in the proportions of saturated FA (SFA) and decreases in proportions of monounsaturated FA (MUFA) [10,11]. The available information on the effects of growth promoting implants on beef FA composition are inconclusive

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