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The extent to which early environment affects wool production of Romney sheep was studied by means of measurement of skin growth, and of fibre numbers and dimensions, of lambs reared to 52 weeks on contrasting planes of nutrition.Measurement of skin growth revealed a series of gradients which generally conformed with growth and development principles. A great degree of individuality among animals in skin growth on various regions was expressed, and it was not possible to prove that plane of nutrition caused differential skin growth among regions.An initial low plane of nutrition had a retarding effect on fleece development and fibre growth, but it could not be decided whether there was a permanent effect on fibre numbers. It seems that this is of little practical importance, since a low plane of nutrition during the major part of the follicle development phase does not appear to impair subsequent unit area production, providing immediate nutrition is good.Examination of fibre attributes, and quantitative fibre growth characteristics on various regions of the body, showed a series of orderly gradients. Large differences existed between the body regions for quantitative production per unit area and this suggests a widely differing nutrient supply of various skin regions.The importance of immediate nutrition is emphasized. It appears that permanent effects of early environment on future productivity take the form of a lesser area on which wool is produced. The efficiency of the processes, apparently, is not affected.

This study was conducted to investigate the variations in clean wool yield percentage among body regions and the relative reliability of each clean yield of 8 regions for predicting the clean yield percentage of the entire fleece of the Japanese Corriedale sheep. The animals examined were 10 Corriedale yearling ewes born in the spring of 1954 in the chugoku Stock Breeding Farm of the Ministr of Agriculture and Forestry. The clean wool yield percentages of small wool samples taken prior to the shearing time at 13 to 14 months after birth, from each sheep in 8 body regions including withers, back, rump, shoulder, side, hip, belly and thigh, were compared with one another and with the clean yield percentage of the entire fleece.The results obtained are as follows.1. Higher clean yield percentages were obtained from the withers (55.42%), back (52.55%), rump (52.62%) and shoulder (52.44%) and lower percen tages from the side (50.94%), hip (51.60%), belly (51.05%) and thigh (49.58%).2. The mean clean yield percentage of the entire fleeces (47.33%) was lower than that of any one of the 8 body regions.3. The difference in the clean yield percentages among the individuals and among the regions was highly significant and the difference among the individuals was greater than that among the regions.4. Correlation coefficients between the clean yield percentages of small wool samples from the 8 regions and those of the entire fleeces showed different values among the body regions; higher coefficients were obtained from the rump, thigh, hip, belly and back and no significant coefficients from the withers, shoulder and side.5. From the results of the present study it seems that among clean wool yield percentages of the small wool samples from the back, rump, hip, belly and thigh, differences in accuracy for prediction of clean yield percentage of the entire fleece are so small and clean wool yield, percentage of each of these five regions would be adequate for use in predicting the clean yield percentage of the whole fleece.

Light-microscope studies reveal distinctive features in the hair- and woolgrowing skin of adult sheep. The epidermis is variable in thickness-usually thin on wool-growing regions and thicker on haired regions. The follicles are mostly in groups containing one, two, or three primary (P) follicles and a number of secondary (S) follicles. The SIP follicle ratios vary from zero to about 30, depending on the breed and body region. The capillaries, myoepithelium of sweat glands, and dermal papillae of the follicles are often reactive for alkaline phosphatase. This enzyme is also asymmetrically distributed in some follicle bulbs and here it might be related in some way to the segmentation of the fibre cortex and perhaps to the formation of crimped wool. The dermal and follicle nerve networks contain cholinesterases. The latter may also contain alkaline phosphatase. Encapsulated end-organs and tactile disks are occasionally present in both hair- and wool-growing skin. Melanocytes, most common near the dermo-epidermal junction, may also be present in the outer root sheaths of the follicles, sebaceous glands, sweat glands, and dermis. Acetylcholinesterase-positive branched cells are invariably present in the epidermis in all regions where there are follicles. Sebaceous glands are associated with all follicles and apocrine sweat glands with the P follicles only. The P follicles also possess erector muscles that react for cholinesterases. Both the subaceous glands and sweat glands are usually larger in haired regions than in wool-growing regions. Large "eccrine" glands open on the naked part of the muzzle.

In a study of wool production per unit area of skin of Merino sheep, two strains of ewes, one strain of rams, and five strains of wethers were examined. A marked variation in weight of wool per unit area was found over the body regions of sheep. A distinct dorsoventral gradient, and some anteroposterior gradients were observed. Sampling positions having wool weights per unit area close to the mean over the body were situated on a line from mid-shoulder to mid-thigh positions. This was consistent for all the groups of animals studied. The mean wool production per unit area varied from sheep to sheep and from strain to strain. These differences were large and highly significant irrespective of level of feeding.