لخّصلي

Antibiotic Use in Livestock
Livestock farming plays a very important role in the agriculture of the European Community. Achieving the best results largely depends on the use of safe and good quality feed. Free movement of safe and good quality food and feed is a key aspect of the internal market, and contributes significantly to the health and well-being of consumers [17].
In terms of animals of economic interest and poultry farms, various active substances are used, including antibiotics, in order to maintain the health of the animals and to have a better yield for breeding. Antibiotics can be administered via feed or by intramuscular injection [18,19]. Medicated feed is an oral route of veterinary medicinal product administration. Medicated feed is a homogeneous mixture of feed and veterinary medicinal products [20].
Regulation (EU) 6/2019 establish rules for the authorization of use of veterinary medicinal products in feeding stuffs, including the manufacture, distribution, advertising, and surveillance of such products [12]. Feed business operators, which handle manufacturing, storing, transporting, or placing medicated feed and intermediate products on the market, must be authorized by the competent authority, in accordance with the authorization system, to ensure both the safety of the feed and the traceability of the products. The labeling of medicated feed stuffs must comply with the general principles set out in Regulation (EC) 767/2009, and are subject to specific labeling requirements, in order to provide users with the information necessary for the correct administration of medicated feed [21]. Such administration must be adequately described in the product information to ensure correct administration and proper dosing of certain veterinary medicinal products, to be administered orally to animals, in feed, or in drinking water, especially in the case of treating groups of animals. The relevant legislation provides the establishment of additional instructions for cleaning of the equipment used in the administration of respective medicinal products, in order to avoid cross-contamination and to reduce resistance to antimicrobials [12]. A large range of synthetic feed additives are included in this category of antibiotics and are used in animal feeding to increase production efficiency and to control different diseases [8].
Recent studies have shown that a significant percentage of all manufacturers add antibiotics to healthy animals’ feed to prevent, rather than cure, diseases [22,23,24,25]. According to Erofeeva et al., livestock accounts for approximately 50% of all antibiotics produced in the world. During the life of an animal, the use of antibiotics can significantly increase a gain in weight by increasing the use of nutrients in the diet, which, in the end, makes it possible to reduce feed costs and shorten the feeding period [25]. Feed manufacturers and authorities establish procedures and instructions for the effective and safe use of authorized and prescribed veterinary medicinal products, for oral administration, other than medicated feeding stuff, such as mixing drinking water with veterinary medicinal products or manually mixing a veterinary medicinal product in feed, which are administered by farmers to food-producing animals. These instructions take into account the scientific recommendations of the European Medicines Agency, established by Regulation (EC) No. 726/2004, on measures to minimize over dosage or under dosage, unintended administration to animals other than those targeted, the risk of cross-contamination, and the release of these products into the environment [12,26]. Homogeneous dispersion of veterinary medicinal product in feed is also essential for the manufacture of safe and effective medicated feed [20].
According to different researchers, reliable data regarding the quantity and patterns of use, dose, and frequency, are not very accurate [27,28,29]. Disease prevention is more effective than treating it. Drug treatment, with antimicrobials in particular, should in no way replace good animal husbandry, biosecurity, and management practices [20]. Excessive weight loss at the beginning of the lactation period leads to the appearance of stress, increasing the susceptibility of animals to diseases, which is why medicated feed has been used for animals for curative and preventive purposes [30]. The US Department of Agriculture noted that approximately 88% of growing swine receive antibiotics in their feed for disease prevention and growth promotion purposes, commonly tetracyclines or tylosin [22]. Some of the most frequently used antibiotics in ruminants are ionophores, a distinctive class of antibiotics that can influence intestinal flora to achieve increased energy and amino acid availability and improved nutrient utilization [22]. Most beef calves in feed lots and some dairy heifers receive this drug routinely in their feed. Ionophores have never been used in humans or therapeutically in animals, because of their specific mode of action. The impact that medicated food has on human health, and implicitly how antibiotic resistance is installed after ingesting food with antibiotics residues, is a topic that we will detail in a later section, but it is worth mentioning that while some bacteria are intrinsically resistant to these drugs, there is currently no evidence to suggest that ionophore resistance is transferable [22,28].
The presence of antibiotics in feed is not desirable due to the antibiotic resistance that the bodies can later acquire. Therefore, the elimination of antibiotics from feed, but improvements in the productivity of pigs and poultry, has been achieved through the use of feed additives, such as omega 3, immunoglobulin, organic and inorganic acids, zinc oxide, yeast derived β glucans, essential oils, prebiotics, probiotics, threonine, cysteine, and herbs and spices [31,32]. On the other hand, the conclusion of another study was that the elimination of prophylactic in-feed antibiotics leads to minor reductions in productive performance and animal health [29].
Advertising for medicated feeding stuffs addressed persons who cannot properly assess the risks associated with their use, and may lead to improper or excessive use of the medicinal product, which may harm public or animal health or the environment [20].