Can Agro-Industrial By-Products Rich in Polyphenols be Advantageously Used in the Feeding and Nutrition of Dairy Small Ruminants?

Abstract

Recently, the interest in industrial by-products produced at the local level in Mediterranean areas, resulting from fruit and vegetable processes, has increased because of their considerable amounts of bioactive compounds, including polyphenols. In this review, we analyze the most recent scientific results concerning the use of agro-industrial by-products, naturally rich in polyphenols (BPRP), in the diets of small dairy ruminants. Effects on milk production, milk and rumen liquor fatty acid profile, metabolic parameters, and methane production are reviewed. The feed intake and digestibility coefficients were generally depressed by BPRP, even though they were not always reflected in the milk yield. The main observed positive effects of BPRP were on quality of the milk’s FA profile, antioxidant activity in milk and blood, a reduction of rumen ammonia, and, consequently, a reduction of milk and blood urea. The expected beneficial effects of dietary polyphenols in small ruminants were not always observed because of their complex and variable matrices. However, owing to the large quantities of these products available at low prices, the use of BPRB in small ruminant nutrition offers a convenient solution to the valorization of residues arising from agricultural activities, reducing feed costs for farmers and conferring added value to dairy products at the local level, in a sustainable way.

Short-Term Effect of the Inclusion of Silage Artichoke By-Products in Diets of Dairy Goats on Milk Quality

“…Frutos et al [46] related the tannins (which are part of the TP) with a reduction in the digestibility of the protein in the rumen, thus releasing less ammonia, and the subsequent urea synthesis in the liver is reduced [47]. Decreases in milk urea were also observed in sheep fed diets with low levels of TP [48,49]. On the other hand, the slightly lower DMI of AB could cause a lower protein metabolism.…”

“…The milk lipid profile was not significantly modified by the inclusion of by-products in the diets at the doses tested. The milk lipid profile is strongly influenced by diet [48,49], in addition to the breed of animals. Some differences were observed between the results of this study with those of Ibáñez et al [45], where they used the same breed: while the palmitic and α-linolenic (C18:3n3) contents were higher (42.6 and 0.400%, respectively), the oleic, linoleic (C18:2n6), conjugated linoleic (CLA) and vaccenic acid (C18:1t11) levels were lower (14.2, 2.46, 0.41 and 0.39%, respectively) than those observed in our experiment, with the exception of AB, which presented a higher level of vaccenic acid.…”

Polyphenols in Farm Animals: Source of Reproductive Gain or Waste?

“…Interestingly, these feed alternatives have been found to contain substantial amounts of polyphenols. In these plants, tannins can be found in almost 80% of woody perennial dicotyledonous species and 15% of annual and herbaceous perennial dicotyledons such as trees, shrubs, legumes, herbs, and cereal grains [ 6 , 7 ]. Many of them are used as animal feeds such as Acacia [ 31 ], Dichrostachys, Dorycnium, Hedysarum, Leucaena, Lotus [ 28 ], Onobrychis, Populus, Rumex and Salix [ 30 ], and Quercus robur with prevalence condensed tannins accounting for up to 20% of the dry matter [ 46 ].…”

“…In extensive livestock production, characterized by low incomes and the limitation of feed resources, it is necessary to look for alternative and available foodstuffs such as shrubs, trees, and agro-industrial byproducts. These products have been found to naturally contain substantial amounts of polyphenols and are more and more used for animal nutrition, having in mind the positive effects of polyphenols on animal growth, performance and health, on adequacy of nutrients utilization, on mitigation of methane emission, and improvement of the quality of animal products [ 2 , 4 , 5 , 6 , 7 , 8 , 9 ].…”

Feeding Agroindustrial Byproducts to Light Lambs: Influence on Growth Performance, Diet Digestibility, Nitrogen Balance, Ruminal Fermentation, and Plasma Metabolites

“…Most byproducts are not potentially edible by humans, and they therefore do not compete directly with human food [2]. Additionally, some byproducts contain bioactive compounds that can improve animal health and the quality of animal products [3,4] while contributing to farm sustainability.…”