Improving the nutraceutical quality of ruminant derived food products

The nutritional richness of ruminant derived foods makes them essential components of a healthy and well balanced human diet. Dairy and meat products provide consumers of high biological value proteins, fats, vitamins and essential minerals. Notwithstanding, scientific evidence from clinical and epidemiological studies shows the strong relationships existing between certain components of ruminant foods and the onset and development of a number of dominant sources of morbidity and mortality worldwide, such as obesity, diabetes, cardiovascular diseases and several forms of cancer. At this regard, the fat content and the fatty acid (FA) composition of dairy and meat products are a constant matter of concern, which led several countries formulating recommended dietary intakes of total fat, individual FA and FA groups. Actually, ruminant foods are sources of both FA with putative negative health effects (e.g., medium-chain saturated FA and some trans FA) and FA which have been recognized to possess beneficial properties (e.g., some conjugated linoleic acid (CLA) isomers and omega-3 FA). Research and development priorities in this field include knowledge advances in lipid digestion and metabolism, a more accurate assessment of the effects of individual FA on human pathologies through biomedical and clinical studies, and the potential of altering the fat content and the FA profile in foods. Concerning the latter aspect, strategies involving animal nutrition and genetics have been explored. Differently from monograstrics, and as a consequence of lipolysis and subsequent extensive biohydrogenation of dietary unsaturated FA occurring within the rumen, FA secretion and deposition in ruminants do not largely reflect dietary FA supply. Notwithstanding, nutrition is a major factor affecting the FA composition of dairy and meat products. Ruminant rations can be quite easily modified (e.g., fresh grass feeding, vegetable and/or marine lipid supplements) to reduce the amount and proportion of saturated FA, contemporarily leading to a several-fold increase of CLA and omega-3 FA (mainly alpha-linolenic acid). Such strategies usually also determine sharp and sometimes undesirable increases in octadecenoic (C18:1) and octadecadienoic (C18:2) trans FA in these foods. The potential for advisable increases of the beneficial very long chain omega-3 FA (e.g., EPA and DHA) in ruminant products is limited, due to the scarce activity of certain enzymes involved in carbon chain elongation and desaturation. At the same time, however, effective explored strategies for enhancing polyunsaturated FA in ruminant foods, such as the use of lipid supplements protected from ruminal biohydrogenation, may be quite expensive for practical and ordinary application. If compared to diet, animal-related factors generally exert a lower influence on the variation of fat and FA content in dairy and meat products. Among explored genetic approaches, breeding programmes for individual genes (e.g., diacylglycerol acyltransferase 1 and stearoyl CoA desaturase) involved in mammary lipogenesis and tissue adipogenesis seem promising. On the whole, considerable progress has been made till now for the improvement of the nutraceutical quality of the lipid fraction of milk and meat, but further studies are needed for the development of enhanced specific nutrient claimed ruminant food products.