The scope for manipulating the polyunsaturated fatty acid content of beef:a review

Since 1950, links between intake of saturated fatty acids and heart disease have led to recommendations to limit consumption of saturated fatty acid-rich foods, including beef. Over this time, changes in food consumption patterns in several countries including Canada and the USA have not led to improvements in health. Instead, the incidence of obesity, type II diabetes and associated diseases have reached epidemic proportions owing in part to replacement of dietary fat with refined carbohydrates. Despite the content of saturated fatty acids in beef, it is also rich in heart healthy cis-monounsaturated fatty acids, and can be an important source of long-chain omega-3（n-3） fatty acids in populations where little or no oily fish is consumed. Beef also contains polyunsaturated fatty acid biohydrogenation products,including vaccenic and rumenic acids, which have been shown to have anticarcinogenic and hypolipidemic properties in cell culture and animal models. Beef can be enriched with these beneficial fatty acids through manipulation of beef cattle diets, which is now more important than ever because of increasing public understanding of the relationships between diet and health. The present review examines recommendations for beef in human diets, the need to recognize the complex nature of beef fat, how cattle diets and management can alter the fatty acid composition of beef, and to what extent content claims are currently possible for beef fatty acids.

Improving beef hamburger quality and fatty acid profiles through dietary manipulation and exploitation of fat depot heterogeneity

Background： Hamburger is the most consumed beef product in North America, but lacks in nutritional appeal due to its high fat content and high proportion of saturated fatty acids （SFA）. Objectives of the present study were to improve the FA profiles of hamburgers made with perirenal fat （PRF） and subcutaneous fat （SCF） when feeding steers different diets along with examining differences in sensory attributes and oxidative stability. Diets included a control diet containing 70：30 red clover silage： barley based concentrate, a diet containing sunflower-seed （SS） substituted for barley, and diets containing SS with 15% wheat dried distillers＇ grain with solubles （DDGS-15） or 30% DDGS （DDGS-30）. Hamburgers were made from triceps brachii and either PRF or SCF （80：20 w/w）. Results： Perirenal fat versus SCF hamburgers FA had 14.3% more （P 〈0.05） 18：0, 11.8% less cis （c）9-18：1 （P 〈0.05）, and 1.82% more total trdns （t）-18：1 mainly in the form of tl 1-18：1. During sensory evaluation, PRF versus SCF hamburgers had greater （P 〈0.05） mouth coating, but the difference was less than one panel unit. Examining effects of steer diet within PRF hamburgers, feeding the SS compared to the control diet increased （P 〈0.05） t-18：1 by 2.89% mainly in the form of tl 1-18：1, feeding DGGS-15 diet led to no further changes （P 〉0.05）, but feeding DDGS-30 diet reduced the proportions of （P 〈0.05） of t-18：1 chiefly tl 1-18：1. Feeding SS and DDGS diets had small but significant （P 〈0.05） effects on hamburger sensory attributes and oxidative stability. Conclusions： Feeding high-forage diets including SS and 15% DDGS, and taking advantage of the FA heterogeneity between fat depots offers an opportunity to differentially enhance beef hamburgers with 18：2n-6 biohydrogenation products （Le., t11-18：1） with potential human health benefits without compromising their sensory attributes and oxidative stability during retail display.

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

Background： The current study evaluated the subcutaneous fatty acid （FA） composition of calf- and yearling-fed steer 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. Results： There 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）l 2-18：1, C14：0, several minor cis-monounsaturated FA （c-MUFA; c9-14：1, c11-16：1, cl 1-18：1, cl 2-18：1, cl 3-18：1, c9-20：1 and cl 1-20：1）, and increased （P 〈 0.05） subcutaneous proportions of tl 1 cl 5-18：2, 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 tl0） compared to non-implanted steers. Conclusions： Overall, current findings show that production systems and growth promotants led to only minor differences in subcutaneous FA composition of beef steers.