# Evaluating Beef Fatty Acid Composition and Lipid Quality in Response to Silage Type and Feeding Intensity During the Finishing Phase

## TL;DR

This study shows that feeding cattle different types of silage and varying feeding intensity affects the fat content and nutritional quality of beef.

## Contribution

The study demonstrates how silage type and feeding intensity can be combined to improve beef fat's nutritional value without compromising its technological quality.

## Key findings

- Grass silage diets increased n-3 fatty acids and improved the n-6/n-3 ratio compared to maize silage.
- Feeding intensity increased intramuscular fat content and the absolute amounts of major fatty acid classes.
- Silage type and feeding intensity interacted to influence specific fatty acid responses.

## Abstract

Beef fat quality is important for both consumers and the meat industry as it affects nutritional value and processing properties. The composition of fatty acids in beef can be modified through feeding strategies applied during the finishing period of cattle. In this study, Holstein–Friesian bulls were fed diets differing in silage type (grass or maize silage) and feeding intensity. We examined how these factors influenced the amount of intramuscular fat and the composition of fatty acids in beef. Increasing feeding intensity mainly increased the amount of fat deposited in muscle, while the type of silage primarily affected the fatty acid composition of the fat. Diets based on grass silage resulted in higher proportions of beneficial n-3 fatty acids and a more favourable balance between n-6 and n-3 fatty acids compared with maize silage-based diets. Overall, the results show that combining appropriate silage type with feeding intensity allows producers to influence the nutritional quality of beef fat without markedly changing its technological quality.

The quality of beef fat depends on both intramuscular fat (IMF) content and fatty acid (FA) composition, which can be modulated by finishing diets. This study evaluated the effects of silage type and feeding intensity on IMF deposition, FA profile, desaturase indices, and lipid quality indices in finishing Holstein–Friesian bulls. Thirty-two bulls were assigned to a 2 × 2 factorial design (n = 8/group) and fed total mixed rations for 120 days based on grass silage or maize silage, under intensive (≈50:50 forage:concentrate, DM basis) or semi-intensive feeding (≈70:30). FA composition of longissimus lumborum lipids was determined by GC-FID, and lipid quality indices were calculated, including the atherogenic index (AI), thrombogenic index (TI), and the hypocholesterolemic/hypercholesterolemic ratio (h/H). Feeding intensity increased IMF content (p = 0.001) and the absolute amounts of major FA classes (g/100 g meat). Silage type primarily affected FA composition by increasing n-3 PUFA and lowering the n-6/n-3 ratio in grass silage diets (p = 0.042). Several FAs showed silage type × feeding intensity interactions (p < 0.05), indicating that the response to dietary energy supply depended on the forage base. Overall, feeding intensity mainly regulated lipid deposition, whereas silage type modulated the nutritional profile of intramuscular fat.