Effect of Different Kind of Polyphenols on Nutraceutical Milk Quality, Ruminal Lipids Metabolism and Rumen Microbiota

Nowadays, European and World policies encourage the reduction of feed inputs in livestock productions. Moreover, in the last decade, there was a steady and inexorable increase of livestock feed costs, due to the increase of row matrixes price. Many farmers, particularly in marginal lands, are in crisis due to these problems; however, these difficulties are much more evident in large intensive farms, because large ruminants have high requirements. In order to overcome these economic problems, it seems evident that the pastoral resource represent a low-cost solution; nevertheless, it does not meet the large-scale needs of intensive farming. Another winning solution could be represented by the use of high biological value agro-industrial by-products. In this way it would be possible to turn a waste, that is disposed with considerable costs, into a food resource for the animals. Most by-products contain notably quantities of secondary compounds, such as polyphenols, which act on digestion and animal performances, but also on the quality of animal derived products. The composition of milk and meat fatty acids can be manipulated by polyphenols naturally present in several plants, modifying the biohydrogenation of polyunsaturated fatty acids, as consequence of changes in ruminal ecology. Small ruminants, even more than large ones, have a remarkable ability to convert feed into products with high nutritional value (meat and milk); they are also endowed with a marked frugality and adaptability to unconventional feed matrices, since they have lower energy requirements. Therefore, a diet formulated with low-input content and with alternative feeds, such as by-products, instead of more expensive products, is an innovative but functional choice. Recently, the increased interest in secondary plant metabolites has led to studies that have shown interesting results regarding animal health and product quality. Plant polyphenols fall into this category but their vastness and chemical diversity imply constant research in the fields of animal nutrition. Furthermore, the use of by-products rich in functional molecules, such as polyphenols, represents a sustainable strategy and meets consumer demand, which increasingly seek natural, healthy and environmentally sustainable products. The rumen and its microbiota represent the key of these issues, because all pathways that convert feed in bioactive compounds occur in a preponderant way in the pre-stomach.