http://www.uco.es/zootecniaygestion/img/pictorex/01_10_22_grasa_1.pdf

Fat deposition, fatty acid composition and meat quality: A review

Current research in meat color

Clinical Biochemistry of Domestic Animals

http://www2.kobe-u.ac.jp/~toyoda/beef/BEEF/Ref/beef%20production_fat.pdf

Innovations in beef production systems that enhance the nutritional and health value of beef lipids and their relationship with meat quality.

Growing consumer interest in grass-fed beef products has raised a number of questions with regard to the perceived differences in nutritional quality between grass-fed and grain-fed cattle. Research spanning three decades suggests that grass-based diets can significantly improve the fatty acid (FA) composition and antioxidant content of beef, albeit with variable impacts on overall palatability. Grass-based diets have been shown to enhance total conjugated linoleic acid (CLA) (C18:2) isomers, trans vaccenic acid (TVA) (C18:1 t11), a precursor to CLA, and omega-3 (n-3) FAs on a g/g fat basis. While the overall concentration of total SFAs is not different between feeding regimens, grass-finished beef tends toward a higher proportion of cholesterol neutral stearic FA (C18:0), and less cholesterol-elevating SFAs such as myristic (C14:0) and palmitic (C16:0) FAs. Several studies suggest that grass-based diets elevate precursors for Vitamin A and E, as well as cancer fighting antioxidants such as glutathione (GT) and superoxide dismutase (SOD) activity as compared to grain-fed contemporaries. Fat conscious consumers will also prefer the overall lower fat content of a grass-fed beef product. However, consumers should be aware that the differences in FA content will also give grass-fed beef a distinct grass flavor and unique cooking qualities that should be considered when making the transition from grain-fed beef. In addition, the fat from grass-finished beef may have a yellowish appearance from the elevated carotenoid content (precursor to Vitamin A). It is also noted that grain-fed beef consumers may achieve similar intakes of both n-3 and CLA through the consumption of higher fat grain-fed portions.

/pdf/a-review-of-fatty-acid-profiles-and-antioxidant-content-in-56v8grm3id.pdf

A review of fatty acid profiles and antioxidant content in grass-fed and grain-fed beef

The effects of grazed grass, grass silage, or concentrates on fatty acid composition and conjugated linoleic acid (cis-9, trans-11-18:2; CLA) concentrations of i.m. fat of steers fed to achieve similar carcass growth rates were investigated. Fifty steers were divided into 10 blocks based on body weight and assigned at random from within blocks to one of five dietary treatments. The experimental rations offered daily for 85 d preceding slaughter were 1) grass silage for ad libitum intake plus 4 kg of concentrate, 2) 8 kg of concentrate plus 1 kg of hay, 3) 6 kg of grazed grass DM plus 5 kg of concentrate, 4) 12 kg of grazed grass DM plus 2.5 kg concentrate, or 5) 22 kg of grazed grass DM. The concentration of polyunsaturated fatty acids (PUFA) in i.m. fat was higher (P < .05) for steers offered ration 5 than for those given any other ration. Decreasing the proportion of concentrate in the diet, which effectively increased grass intake, caused a linear decrease in the concentration of i.m. saturated fatty acids (SFA) (P < .01) and in the n-6:n-3 PUFA ratio (P < .001) and a linear increase in the PUFA:SFA ratio (P < .01) and the conjugated linoleic acid concentration (P < .001). The data indicate that i.m. fatty acid composition of beef can be improved from a human health perspective by inclusion of grass in the diet.

Fatty acid composition, including conjugated linoleic acid, of intramuscular fat from steers offered grazed grass, grass silage, or concentrate-based diets.

The eating quality of meat of steers fed grass and/or concentrates

As a plant group, forage legumes present some unique advantages and disadvantages for ruminant production. When compared to grasses or cereals their main advantages are generally (i) low reliance on fertilizer nitrogen (N) inputs, (ii) high voluntary intake and animal production when feed supply is non-limiting and (iii) high protein content. The main disadvantages of forage legumes are generally (i) lower persistence than grass under grazing, (ii) high risk of livestock bloat and (iii) difficulty to conserve as silage or hay. In comparison to grass or legume monocultures, grass + legume mixtures have particular advantages such as more balanced feeding values, increased resource use efficiency and increased herbage production. However, maintaining the optimum legume contents (40-60% of herbage dry matter) to achieve these benefits remains a major challenge on farms. When compared to ruminant systems based on grass or cereals supplemented with fertilizer N, forage legume based ruminant systems tend to have...

Forage Legumes for Grazing and Conserving in Ruminant Production Systems

Fatty acid composition of intra-muscular triacylglycerols of steers fed autumn grass and concentrates

The effects of space allowance during transportation on physiological, haematological and immunological responses in nine-month old bulls (250 kg) were assessed before and after a 12-h road journey. Following transport, animals transported at a spatial allowance of 1.27 m 2 had higher (P ≤ 0.001) non-esterified fatty acid concentrations than control. The stimulated production of interferon-γ, in response to concanavalin-A and keyhole limpet haemocyanin, and plasma cortisol were not different at the 0.85 m 2 and 1.27 m 2 stocking densities. Glucose and albumin concentrations were higher (P ≤ 0.001) post-transport in all transported animals than control. The percentage lymphocytes was reduced (P ≤ 0.001) and neutrophil percentage and the number of neutrophils were increased (P ≤ 0.001) in all transported treatments. There were no changes (P > 0.05) in monocyte numbers, monocyte percentage or platelet numbers following transportation. The haematocrit values were higher (P ≤ 0.001) in the transported treatments while RBC numbers were higher (P ≤ 0.001) in the animals transported at a spatial allowance of 1.27 m 2 than control. Protein, globulin, urea and lactate concentrations, and white blood cell numbers were not changed at any time during the study. The concentration of β-hydroxybutyrate was lower (P ≤ 0.001) in all animals following transport. Plasma haptoglobin concentrations were unchanged following transportation while plasma fibrinogen concentrations were reduced in all transported treatments. There were no differences among treatments in rectal temperature or live weights pre- and post-transport. The results indicate that within the conditions of the study, there was no welfare advantage in transporting bulls at 1.27 m 2 versus the standard spatial allowance of 0.85 m 2 on a 12-h road journey.

Edward G. O'Riordan

Papers

Fatty acid composition, including conjugated linoleic acid, of intramuscular fat from steers offered grazed grass, grass silage, or concentrate-based diets.

The eating quality of meat of steers fed grass and/or concentrates

Forage Legumes for Grazing and Conserving in Ruminant Production Systems

Fatty acid composition of intra-muscular triacylglycerols of steers fed autumn grass and concentrates

Effects of transporting bulls at different space allowances on physiological, haematological and immunological responses to a 12-h journey by road