**3.12. Therapeutic silage**

and volatile FA concentrations. Besides, the environmental factors inside the silo, e.g. moisture content, pH, acid and gas composition, are likely to influence the species composition of the fungal population and the extent to which mold colonization occurs. Oxygen ingress causes excessive moisture or dryness, condensation, heating, leakage of rainwater and insect infestation of the silo, leading to undesirable growth of microaerobic acid-tolerant fungi, which may lead to mycotoxins production in this substrate [75]. Mycotoxin-producing molds, Bacillus sps and *Listeria monocytogenes* in aerobically deteriorated silage form a serious risk to the quality and safety of milk and to animal health. An average of 32% positive cases observed with most frequent fungal species from *Aspergillus, Penicillium* and *Fusarium* in pre- and postfermented sorghum silage samples [76]. Thus, periodic monitoring is essential to prevent the

occurrence of mycotoxicosis particularly in countries with hot and humid climates.

cipal product of silage fermentation, which reduced aerobic spoilage.

Addition of high levels of propionic acid is effective against aerobic spoilage, but its use has been restricted because of its corrosive nature, relative expensiveness, involvement in VFI depression and variable sensitivities of yeast [77]. Control of silage fermentation by microorganisms seems to be a safe and inexpensive alternative, and in this line, LAB inoculation has been recommended to improve the aerobic stability of silage [8]. Killer yeasts (e.g*. Kluyveromyces lactis*) are known to secrete a killer protein that is lethal to specific yeasts (e.g. *Saccharomyces cerevisiae*) in a model of silage fermentation [78]. Genetically modified killer strain of *K. lactis* constructed to avoid dependence on substrates of lactose/lactic acid, a prin-

The mechanisms by which the inoculants alter silage fermentation and potentially improve animal performance are numerous. It supports accelerated post-ensiling decline in pH enabling quality silage production, improves stability and DM preservation, conserves nutrients, enhances aerobic stability and improves voluntary intake, nutrient utilization and efficiency of production. There may be increase in lactic/acetic acid ratio and reduction in proteolysis and protein deamination, thereby allowing better utilization of WSC and increase in DM recovery [79]. The problem of aerobic instability could be prevented by the use of microbial inoculant *L. buchneri*, a heterofermentative LAB, which could improve the aerobic stability of silages through the production of acetic acid from lactic acid during the anaerobic phase of silage conservation [71, 80, 81]. The natural populations of LAB in fresh crops are often heterofermentative and low in number, and thus homofermentative bacteria are used as inoculants to improve silage preservation. This accelerates the initial phase of the fermentation process via anaerobic degradation of WSC into lactic acid with a rapid decrease in pH and thereby preventing growth of spoilage microbes, molds and other contaminants and supporting preservation and storage without further deterioration in quality. Usually, selected homofermentative LAB have been used to improve the efficiency of the fermentation process to minimize DM and nutrient losses over conservation [82]. To prevent the aerobic deterioration of silage, heterofermentative LAB species, such as *L. brevis* and *L. buchneri*, have been developed as silage

*3.11.1. Controlling spoilage*

28 Ruminants - The Husbandry, Economic and Health Aspects

*3.11.2. Microbial inoculants*

Phytochemicals have antimicrobial properties against *E. coli*. The use of a high-quality PSMcontaining forage may have the dual benefit of being a good-quality forage and reducing *E. coli* shedding [88]. Significant potential to use plants rich in bioactive compounds (saponin and tannin) for enhancing animal health and productivity that include reproductive efficiency, milk and meat quality improvement, foam production/bloat control, methane production [89] and Nematode control [90] has now been realized. The physicochemical structure and concentration of the phenolic compounds in the diet modulate the beneficial effects, and therefore, conceptualization of producing "therapeutic silage" involving forages rich in desired bioactive components would harness clinical and health benefits, besides modifying the yield and quality of meat and milk.
