Ruminant Trace Minerals Deficiency and the Potential Link Between the Source and Rumen Interaction. A Review

Abstract

Dietary inclusion of trace minerals (TM), such as copper (Cu), manganese (Mn) and zinc (Zn) is of importance to cover the ever-evolving requirements for growth, production, and reproduction in ruminants. Various sources of TM are commercially available, such as inorganic (ITM), organic (OTM) or hydroxy (HTM) forms, however their bioavailability and efficiency to improve ruminant zootechnical parameters may be highly influenced by ruminal solubility and effects on the rumen environment. The objective of this review was to compile the most up-to-date information on the ruminal solubility of ITM, OTM and HTM, and their effects on fermentation parameters and rumen microbiota, aiming to support specialists from the animal feed industry when choosing TM products for ruminant supplementation. Some commonly used ITM sources, like sulfates, have a high ruminal solubility, while oxides are less soluble. The ruminal solubility of OTM is mostly found to be high, however data on these TM forms are still lacking. Regarding HTM, ruminal solubility is reported to be low, nevertheless results are inconsistent. Considering rumen fermentation, ITM show a negative effect, OTM might improve, while HTM do not affect parameters like dry matter degradability, volatile fatty acid production, pH, or microbial protein synthesis. As to rumen microbiota, ITM do not affect microbial populations; OTM could decrease abundance of some specific bacteria, like fibrolytic microorganisms, while studies with HTM are missing or inconclusive. Further research is necessary to better understand the ruminal solubility kinetics of TM sources and the different interactions with fermentation parameters and rumen microbiota to successfully apply precision TM supplementation of ruminants, tackling deficiency occurrences.