## 1 Introduction  
Goats are ideal domesticated animals for farming in arid and semiarid areas because of their adaptability and eating habits. The Altiplano region of San Luis Potosi, Mexico produces 620,000 head of livestock, which amounts to 7.1% of national production and provides 3212 tons of meat per year [1, 2]. In this region, goat production is carried out extensively under traditional management, in which goats gaze on native vegetation and receive little to no supplementary feeding. In most cases, food is complemented with farm produce (mainly corn stubble and bean straw), and some herds receive common salt as their only mineral supplement [3]. On the other hand, in highly developed countries that supplement animal feed with high amounts of minerals, pollution increases because excess minerals are secreted [4]. For example, US dairy producers use feed that exceeds the _Nutrient Requirements of Dairy Cattle_ dietary phosphorus recommendations by 45-50% [5, 6]. For this reason, controlled mineral supplementation alternatives should be sought to avoid both mineral deficiency and overload. An alternative for mineral supplementation in adequate amounts is the use of boluses (e.g., intraruminal bowel iron matrix or dental cement). The bolus's role is to support the targeted physiological functions of animals over a specific period. They are designed to release over periods where animals are at risk or to fulfill specific needs, such as to correct selenium (Se) deficiencies in sheep [7,8] or to supply copper oxide (AOCu) wire [9]. However, few studies have been conducted on the supplementation of macro elements such as phosphorus. Deficiencies of this mineral in goats have been associated with decreased rates of conception, increased abortions, low birth weight, lower feed consumption and higher offspring mortality [5,10]. Therefore, there is a need to efficiently supplement phosphorus to grazing livestock and thus cover their requirements (i.e., 11.6 mg/kg body weight/day) [11] in the most critical physiological stages: at the beginning of breeding season and during lactation [10]. Mineral supplementation is adequate if the animal's diet is marginal in a mineral but inadequate if that mineral is severely deficient. Unless a documented deficiency exists, it is best not to provide 100% of a mineral, because an excess may depress the absorption of another [12]. Solutions to this problem thus far, such as intraruminal boluses like iron matrices or dental cement, have been invasive to animals. Meanwhile, other non-invasive commercial supplements have proven ineffective and have been shown in some countries to not contain the phosphorus concentration indicated on the label, in addition to the fact that there is no control of the amount of supplement consumed by animals. Therefore, the problems associated with phosphorus deficiencies persist even when mineral supplements are provided to goats [13]. In the present work, a new alternative of boluses to slowly release minerals is proposed. It consists of an oleogel, a type of material that could be non-aggressive to phosphorus supplementation. An oleogel is a material made by the gelation of low molecular weight gelators (molecular weight \(<\) 3000 Da) with amphiphilic characteristics. Oleogelation can be achieved by initially dissolving a gelator by heating it in the organic solvent and then cooling the solution to a temperature below the solubility limit of the gelator. Under this condition, gelators such as n-alkanes [14], monoglycerides [15], 12-hydroxysteratic acid [16,17], some amides [18], lecithin [19,20] and some plant waves (e.g., candellilla wax, rice bran wax and carnauba wax) [21, 22, 23, 24] go through spontaneous molecular assembly in vegetable oils and mineral oil [20, 25, 26, 27, 28].