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2024

Sammendrag

Ensiling is a common mode of preservation of animal feed. In this process, the feed undergoes lactic acid fermentation in an anaerobic environment, which decreases pH and inhibits degradation of the feed and its nutritive value. Common silos include top loaded tower silos, side loaded bunker silos (also called horizontal silos), underground pit and trench silos, and bales and tubes wrapped in plastic film. Previous studies have revealed that the type of silo often have an impact on silage properties and feed value, but these effects can vary between silage materials. Silage density is another key factor for silage nutritive value and losses. Generally, high density results in smaller losses than low density, both in bunker silos and bales, but the density effect can also be influenced by properties of the ensiled material. The objectives of this literature review were to identify factors and conditions that can modify the effect of i) silage density, and ii) silo type on dry matter losses, leaching of nutrients, fermentation characteristics, silage feed value and mycotoxins contamination. A systematic literature search was carried out in in the Web of Science core collection platform of databases. Most studies showed positive correlations between silage density, and fermentation and feed value, and negative correlations with DM losses. The majority of these studies were conducted at laboratory scale and there was also a great variation in the magnitude of these effects. Further investigations at farm scale may provide more information about the consistency of these effects across experimental scales. The silo type comparisons indicate that silage bales, bags and tubes can be favourable for silage quality and dry matter preservation compared to bunker silos, but information on silo type effects on important crops such as maize is missing.

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Sammendrag

Housing and indoor feeding of sheep is required throughout the cold season, which can last more than half a year, in Nordic highlands and Alpine regions. This study aimed to examine and evaluate the housing costs, including labour requirements, according to type of sheep housing system and degree of mechanized feeding by investigating systems commonly used in Nordic and Alpine regions. Detailed cost data were obtained from 61 surveyed sheep farmers in Norway with sheep houses built between the years 2008 and 2015. Costs were calculated for a baseline scenario (2021-prices) as well as for five scenarios at low and high discount rates and opportunity cost of labour, and high energy prices. The median (interquartile range) flock size was 150 (100) winter-fed sheep. Houses with slatted floors were more expensive than deep-litter systems. Costs of bedding material and feed waste were however higher, and the net value of the manure were lower in houses with deeplitter systems. At the baseline assumptions, overall net housing costs per sheep was not statistically different among the main housing types studied. Multiple regression analyses showed that net housing costs per sheep were lower in larger flocks and for centrally located farms (control variables). Undertaking daily chores, such as feeding of roughages twice a day rather than once, resulted in significantly higher net housing costs. Mechanized feeding of roughages, and even more so for concentrates, were not economically justified since labour savings were not sufficient to pay for the additional capital costs. A round bale chopper lowered net housing costs, significantly at a high labour cost. None of the scenarios found slatted floors to be significantly more expensive than deep-litter systems. High costs of labour and capital favoured deep-litter systems, while slatted floor systems were more advantageous at rising prices of energy that resulted in increased values of organic manures and costs of feed wastes and bedding materials. The study was based on a decade old data from common Norwegian sheep house variants. Farmers that consider constructing a new sheep house today, still must compare these variants as their main alternatives. We encourage other researchers to include effects of housing systems and mechanized feeding on animal performance, health, and welfare. Moreover, future studies should preferably also be undertaken in other environmental or socio-economic settings to produce more general results.