# Inclusion of Polyphenol-Rich Olive Cake in Beef Cattle Diets: Effects on Meat Quality and Nutritional Traits

## TL;DR

Adding olive cake to beef cattle diets improves meat's nutritional value and sustainability without harming quality.

## Contribution

Demonstrates that olive cake can be used up to 15% in cattle diets to enhance meat quality and sustainability.

## Key findings

- Olive cake inclusion improved the lipid profile of beef with higher beneficial fatty acids.
- Meat from treated animals had increased antioxidant compounds from olives.
- Up to 15% olive cake can be used in diets without negatively affecting meat quality.

## Abstract

Large quantities of by-products are generated during olive oil production, many of which are still underutilized despite their high nutritional and functional potential. Olive cake is one such by-product, characterized by a valuable content of beneficial fatty acids and natural antioxidant compounds. The aim of this study was to evaluate whether partially destoned dried olive cake can be included in the diets of beef cattle and to assess its effects on meat quality and nutritional value. Limousin bulls in the finishing stage were fed diets containing olive cake at two inclusion levels and compared with animals receiving a conventional diet. The inclusion of olive cake did not negatively affect meat acidity or visual appearance, indicating that overall meat quality was preserved. Conversely, meat from olive cake-fed animals exhibited an improved lipid profile, with higher proportions of fatty acids considered beneficial for human health. Moreover, these animals produced meat with increased concentrations of natural antioxidant compounds derived from olives. Overall, the results demonstrate that olive cake can be effectively used in beef cattle feeding to enhance the nutritional quality of meat while simultaneously promoting more sustainable livestock production through the valorization of agro-industrial by-products.

This study involved 45 finishing Limousin young bulls (initial BW 350 ± 15 kg; aged 250 ± 20 days) reared under commercial conditions and randomly assigned for 250 days to three dietary treatments: a control diet without olive cake (CTR), and diets including partially destoned dried olive cake at 10% (OC10) or 15% (OC15) of dry matter. The effects of the dietary inclusion of partially destoned dried olive cake (DOC) on the physicochemical properties, intramuscular fatty acid composition, nutritional lipid indices, and antioxidant profile of the Longissimus dorsi muscle were evaluated. Meat pH was measured at 45 min, 24 h, and 7 days of aging. Instrumental color, proximate composition, fatty acid profile, lipid nutritional indices, total phenolic content (TPC), individual polyphenols, and antioxidant capacity were determined. Data were analyzed by ANOVA using PROC GLIMMIX in SAS, with orthogonal contrasts to evaluate linear and quadratic responses to olive cake inclusion. Treatments did not affect post mortem pH, and color differences observed at 24 h were not present after 7 days of aging. Crude protein content was lower in OC-fed groups, while total lipid content tended to increase; sodium chloride concentration was higher in OC15 meat. Olive cake supplementation reduced hypercholesterolemic saturated fatty acids and increased stearic, oleic, and polyunsaturated fatty acids, including α-linolenic acid, EPA, and DPA, improving PUFA/SFA and UFA/SFA ratios and reducing atherogenic and thrombogenic indices. Despite a higher peroxidability index, OC groups showed greater muscle TPC and antioxidant capacity, the presence of detectable hydroxytyrosol and tyrosol suggests a possible contribution of dietary olive phenolics or their metabolites, although the exact mechanisms underlying their appearance in muscle tissue remain to be fully elucidated. Overall, partially destoned DOC can be included up to 15% of the finishing diet to improve beef nutritional and functional quality within sustainable circular systems.