BIOL-800Wool Growth
The wool-producing ‘factory’ is the 50 million or so follicles embedded in the skin of sheep. This unit covers in detail, how these follicles form, what cellular and molecular processes produce the fibre, how genetics and nutrition affect these processes, and how genetic engineering might be used to produce a better fibre. With an understanding of the biology of the skin and the fleece, the characteristics of the wool follicle and fibre can be related to production, technology and the processing of wool.
This theme examines the effect of hormones, nutrition and genotype on wool production (quantity & quality).

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BIOL-800-050The Effect of Genotype on Wool Growth
This topic demonstrates the variations in fleece characteristics between different strains of sheep.
BIOL-800-050-100Whole body differences that affect wool production
This module demonstrates variations in fleece characteristics between different strains of sheep maintained under the same environmental conditions and describes the whole body differences that may give rise to these variations.
BIOL-800-050-200The Environment of the Sheep
Variation in wool growth between sheep within genotypes reflect the effects of the environment and physiology of the sheep. Environmental effects include both the external environment of the sheep, such as climate and day length, and the internal environment of the sheep, such as pregnancy and disease. This module lists the components of the sheep’s environment.
BIOL-800-100The Effect of Hormones on Wool Growth
The impact of the endocrine system on wool growth is examined in detail, including the effects of the catecholamines, growth hormones, cortisol, insulin, sex hormones, thyroxine and cytokines.
BIOL-800-100-050Can Hormones or Methionine Improve Wool Production of Pregnant and Growing Sheep
This module describes how hormones or amino acids can be used to manipulate wool growth in pregnant and growing sheep.
BIOL-800-100-100Indirect Effects of Hormones on Wool Production
This module summarises how indirect effects can influence wool production using nutrient partitioning as an example.
BIOL-800-100-150Catecholamines and Wool Growth
This module describes the endocrine mechanisms involved in the short term response to stress and how it affects wool production.
BIOL-800-100-200Stress Hormones
The response to stress can either be short or long term. This module describes the role and location of ACTH in the sheep.
BIOL-800-100-250Stress Response of Sheep
This module describes how sheep respond to stress. Stress can be induced by animal-animal, animal-human interactions or in response to an immune reaction, for example in response to flystrike.
BIOL-800-100-300The Effect of Cortisol on Wool Production
This module describes the endocrine mechanisms involved in the long term response to stress and how it affects wool production.
BIOL-800-100-350The Effect of Growth Hormone and Insulin-like Growth Factor Interactions on Follicles
This module describes the location of growth hormone and IGF receptors and binding proteins in the follicle.
BIOL-800-100-400The Effect of Growth Hormone on Wool Production
This module describes the effect of growth hormone on wool production.
BIOL-800-100-450The Effect of Insulin on Follicles
This module describes the function of insulin in the body and its effect on the follicle.
BIOL-800-100-500The Effect of Insulin-like Growth Factor on Wool Production
This module describes the effect of the insulin-like growth factors on wool production.
BIOL-800-100-550The Effect of Photoperiod on Wool Growth
This module describes the effect of photoperiod on wool growth and the role of melatonin and prolactin.
BIOL-800-100-600The Effect of Sex Hormones on Follicles
This module describes the function of gonadotropins (sex hormones) in the body and its effect on the follicle.
BIOL-800-100-650The Effect of the Pituitary on Wool Production
This module describes the hypothalamic-pituitary axis and the effect of the pituitary on wool production.
BIOL-800-100-700The Effect of the Thyroid on Wool Production
This module describes the effect of the thyroid gland on wool production.
BIOL-800-100-800The Immune Response and Follicle Function
This module describes the effect the immune response may have on wool production.
BIOL-800-100-850The Use of Hormones to Manipulate Annual Wool Production
This module describes how hormones may be used to manipulate wool production throughout the year.
BIOL-800-200The Influence of Nutrition on Wool Growth
Relationships between skin and follicle traits, and wool growth are described.
BIOL-800-200-050Relationship between fibre length and diameter
Nutrition is the major environmental factor influencing the realisation of genetic potential for wool production and wool quality. Wool growth rate is constrained by feed intake and the supply of protein, energy, vitamins and minerals provided by the diet. This module describes the how length and diameter of the fibre change under different conditions, for example, nutrition, cold stress, thyroidectomy, cortisol administration, season and unbalanced amino acid supply.
BIOL-800-200-100Essential amino acids for wool growth
This module describes the effects of proteins with different amino acid composition on wool growth and lists the amino acids that are essential for wool growth.
BIOL-800-200-150The effect of protein supply on wool production
This module describes the nutritional factors limiting wool growth and the response of wool growth to protein that is not degraded in the rumen.
BIOL-800-200-200Lysine and wool growth
This module examines the effect of the amino acid lysine on wool growth.
BIOL-800-200-250Sulfur amino acids and wool growth
Nutrition is the major environmental factor influencing the realisation of genetic potential for wool production. Wool growth rate is constrained by feed intake and the supply of protein and energy provided by the diet. This module illustrates that both cysteine and methionine are limiting amino acid for wool growth, that rumen by-pass proteins can improve wool growth, that cysteine supply can influence the proportion of paracortex in the fibre, the sources of cysteine for wool growth, the relationship between genetics and cysteine metabolism and discusses the potential that this has for genetic selection.
BIOL-800-200-300Vitamins and wool growth
Nutrition is the major environmental factor influencing the realisation of genetic potential for wool production. Wool growth rate is constrained by feed intake and the supply of protein, energy, vitamins and minerals provided by the diet. This module examines the effect of vitamin A and D on wool growth.
BIOL-800-200-350Zinc and wool growth
Nutrition is the major environmental factor influencing the realisation of genetic potential for wool production. Wool growth rate is constrained by feed intake and the supply of protein and energy provided by the diet. This module examines the effect of zinc on wool growth.