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From the opening of the silo to the end of its feeding, the silage face undergoes materials and energy flow with the external environment. Oxygen is the cause of the deterioration of silage quality. It promotes a series of aerobic microorganisms to eat high-nutrient substances (such as water-soluble sugars and lactic acid), which leads to a decrease in the dry matter and energy content of the silage, and may even result in the production of mycotoxins. The silage face is susceptible to oxidation, but effective management of the silage face can help preserve more nutrients for ruminants. The paper introduces the structural characteristics of silage, gas exchange, volatilization of fermentation ends, and microbial activities that occur on the silage face. It also describes the conditions that lead to aerobic deterioration on the silage face. Additionally, the paper reviews the role of silage face management, such as management principles, daily removal rate, silage remover, and feeding principles, in ensuring personnel safety, preserving nutrients and reducing dry matter losses, to provide a reference for implementing effective feed-out practices. [ABSTRACT FROM AUTHOR]

Near-infrared reflectance spectroscopy (NIRS) is an inexpensive, rapid, environment-friendly and non-invasive analytical technique that has been extensively applied in the analysis of the dietary attributes and the animal products. Acquisition of dietary attributes is essential for nutritional diagnoses to provide animals with reasonable diet. Traditionally, the calibration equations for the prediction of dietary attributes (e. g. crude protein) are developed from feed NIR spectra and the results of conventional chemical analysis (i. e. reference data). It is difficult to obtain the NIR spectra of forages consumed by grazing animals, so the method of this calibration is inappropriate for free-grazing herbivores. Feces, as the animal's metabolites, contain the information about both the animal's diet and the animal itself. Recently, Fecal-NIRS (F. NIRS) has been directly used to monitor diet information (botanical composition, chemical composition and digestibility), based on correlation between reference data and fecal NIR profile. Subsequently, some additional application (such as sex and species discrimination, reproductive and parasite status) of F. NIRS also is outlined. In the last, application of NIRS in animal manure is summarized. NIRS was shown to be an alternative to conventional wet chemical methods for analyzing some nutrient concentrations in animal manure rapidly. Overall, this paper proves that F. NIRS is a rapid and valid tool for the determination of the dietary attributes and of the physiological status of animal, although more efforts need to be done to improve the accuracy of the F. NIRS technique. Several researchers in English have reviewed the applications of F. NIRS. In China, however, there is a paucity of research and application regarding F. NIRS. We expect that this paper in Chinese will be helpful to the development of F. NIRS in China. At the same time, we propose NIRS as a simple and rapid analytical method for predicting the main chemical composition (dry matter, organ matter, total solid, volatile solid, total nitrogen, total Kjeldahl nitrogen and ammonium nitrogen) in animal manure.