Thursday March 27, 2014

Day 65..

This morning in workshop practical we had two brand newly punctured tractor tyres to repair! We started off by using bead breaking equipment to remove the tyre off the rim. We then had to deflate the tube so that it could be removed from inside the tyre - from the valve end first!
Once removed the tube is blown back up to discover where the loss of air is coming from and this area marked with chalk. We then deflated the tube again so that the area could be cleaned with some sandpaper - to remove any debris that is clinging to the surface, before preparing the area with a buffer lubricant. A layer of vulcanising glue was then applied ready for the patch to stick too. The tube is then reassembled inside the tyre and the tyre reassembled onto the wheel - when it comes to seating a tyre you will need to apply lubrication so the bead will slide and seat correctly on its rim and not fold under itself. The wheel is then stood up and using a compressor, air is used to pump the tyre back up - taking care to stand to the side at all times! Hey presto job done!

We sat a 'class test' in livestock husbandry with regards to sheep breeds and stratification - whereby particular breeds that have been occupying specific environments to which they have adapted too are then connected by the movement of lambs and older animals from higher, to lower ground to produce the best end product. In upland areas there are again specific breeds, these and older draft mountain ewes are crossed with the longwool breeds. The cross results in a half-bred or mule. Male lambs are generally sold as stores for fattening in the lowlands whilst the ewe lambs are transferred to the lowlands to be crossed with a lowland breed. In the lowlands, the mules and half-breds are crossed with lowland sires to produce lambs that can be fattened on summer grass. Slower growing lambs join the store lambs that have arrived from the hill and upland areas to be fattened on root crops over the autumn and winter months.
We then discussed the mammary gland - in cattle. The mammary gland is a highly modified sweat gland and the lining of the teat and ducts is essentially modified skin. Milk is produced by cells lining the alveoli - small structures deep within the udder. The alveoli are surrounded by muscle cells and when the stimulus for milk let down occurs, the muscle contracts and squeezes the milk into the ducts that lead to the gland cistern and the teat producing the milk for a calf or for a human to collect!