Wednesday, 15 January 2014

Sheep of the month - January 2014

This is the first in a new series of regular blog posts linking agricultural practice and isotopic composition. This relationship is the core of what we're working to understand at the ASIL in Kiel. 

Jacob sheep in a snow covered field eating hay
Jacob sheep eating hay during snow cover

Breed notes
Jacob sheep are piebald, with black-and-white faces and spotted bodies. Both males and females can have 2-6 horns. They are an unimproved (primitive) sheep breed of unknown origin and antiquity. They have a medium fine fleece and no outer hairy coat, unlike other primitive breeds which typically have a fine inner coat and hairy outer coat. More info:

Isotope notes
In cold climates, alternative fodder sources must be provided to grazing animals during periods of snow cover. In the past, this has typically been summer vegetation, cut and stored as hay, but it might include straw, chaff and spoiled grain. Additional 20th/21st century options are silage (fermented cut vegetation) and commercial ‘cake’.

Isotopically speaking, this means that animals are consuming summer vegetation in winter. This is likely to affect their tissues’ isotope values, because plant species availability and plant isotope values vary seasonally in response to temperature, humidity and growth rates. Mean tissue values for animals receiving fodder may therefore be shifted overall towards a summer signal when compared to other species which do not. 

Many thanks to Punkin's Patch for permission to use the photo!