Stephen Hong-Wei Wu

Rumen-stable delivery systems

Ruminants have a distinct digestive system which serves a unique symbiotic relationship between the host animal and predominantly anaerobic rumen bacteria and protozoa. Rumen fermentation can be both beneficial by enabling utilization of cellulose and non-protein nitrogen and detrimental by reducing the nutritive value of some carbohydrates, high biological value proteins and by hydrogenating unsaturated lipids. In addition it can also result in the modification and inactivation of many pharmacologically active ingredients administered to the host animal via the oral route. The advances in ruminant nutrition and health demand a rumen-stable delivery system which can deliver the active ingredient post-ruminally while simultaneously meet efficacy, safety and cost criteria. In contrast to drug delivery systems for humans, the demand for low-cost has hindered the development of effective rumen-stable delivery systems. Historically, heat and chemical treatment of feed components, low solubility analogues or lipid-based formulations have been used to achieve some degree of rumen-stability, and products have been developed accordingly. Recently, a polymeric pH-dependent rumen-stable delivery system has been developed and commercialized. The rationale of this delivery system is based on the pH difference between ruminal and abomasal fluids. The delivery system is composed of a basic polymer, a hydrophobic substance and a pigment material. It can be applied as a coating to solid particles via a common encapsulation method such as air-suspension coating. In the future, the delivery system could be used to deliver micronutrients and pharmaceuticals post-ruminally to ruminant animals. A further possible application of the delivery system is that it could also be combined with other controlled delivery devices/systems in order to enhance slow release or to achieve targeted delivery needs for ruminants. This paper discusses the rumen protection and the abomasal release mechanism of the polymeric coating. It also reviews other rumen stable delivery systems and methods for evaluating their in vitro and in vivo performance.

Design parameters for post-ruminal drug delivery systems and rumen-stable products

Publisher Summary Concerns for animal well-being and competitive livestock industries underlie the requirement for drug and nutrient delivery systems for ruminants that protect active ingredients from ruminal fermentation. In addition to delivering drugs or nutrients directly to the small intestine for absorption, commercially viable delivery systems must meet safety, and cost criteria. Compared with products developed for human use, cost constraints have impeded the development of effective post-ruminal delivery systems and rumenstable products. This chapter outlines both the physiological and technical considerations encountered in the design of effective post-ruminal delivery systems. It discusses the formulation strategy for a pH-dependent rumen-stable coating system and methods for in vitro and in vivo evaluation of post-ruminal delivery systems. It also discusses the ruminant digestive system and the digestive system of a simple-stomached animal and the difference between these two.