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Losses of dry matter and metabolisable energy (ME) occur in silage making due to delayed harvest and also between field and feed trough due to fermentation and aerobic spoilage. Farmers should aim to exert greater control of silage making operations to improve timeliness of harvest and to minimise losses of nutrients. Concentrate input per unit of milk production is often higher than optimal which is more often a reflection of low silage quality than of wasteful overfeeding. A week's delayed harvest of grass is estimated to incur a net cost of 13 pence per cow per day of winter feeding. Mowing a dry crop and spreading it out to maximise rate of water loss during the wilting period can reduce losses in the field. Consolidation of crop in the silo to achieve a minimum fresh weight density of 700 kg/m3 and dry matter (DM) density of 210 kg/m3 will help to minimise losses during the storage period, paying particular attention to the outermost layer which should be covered with an oxygen barrier film. A feed-out progression rate of at least 1 metre per week in winter and 1.5 to 2 metres per week in summer, coupled with harvesting a clean crop with low yeast and mould counts will help to reduce losses during feed-out. Many bunker silos are too old, too small, have no safety rail and are over-filled. Safety issues should be considered at all stages of silage making. Appropriate steps should be taken wherever possible to minimise risk of injury. [ABSTRACT FROM AUTHOR]

When silage is exposed to air on opening the silo, or after its removal from the silo, fermentation acids and other substrates are oxidized by aerobic bacteria, yeasts and moulds. The aerobic stability of silage is a key factor in ensuring that silage provides well-preserved nutrients to the animal with minimal amounts of mould spores and toxins. In this paper, key findings and recent developments are reviewed, and findings of recent research are integrated in terms of four themes: (i) the most significant biochemical and microbiological factors, (ii) physical and management factors, (iii) type of additive and (iv) silo sealing. The development of yeasts and moulds during plant growth, and during field wilting or storage, and the concentration of undissociated acetic acid in silage are important microbiological and biochemical factors affecting aerobic stability. Silage density and porosity are key physical factors that affect the rate of ingress of oxygen into the silage mass during the feed-out period. A target for potential silage aerobic stability is 7 d including time in the feed trough. To achieve this target, speed of harvest should be coordinated with packing tractor weight to achieve a minimum silage density by the time of feed-out of 210 kg DM m−3, maximum proportional porosity of 0·4 and a rate of silage removal, which matches or exceeds the depth of air penetration into the silo. The use of additives to increase aerobic stability is advisable when there is the risk of these objectives not being met. Novel microbial approaches to solving the problem of silage aerobic deterioration are needed. [ABSTRACT FROM AUTHOR]