« Milk and honey are sweetness » Gilbert Durand

Let’s see how milk is seen in mythology: -In ancient Egypt, milk was the gift of the goddess Isis to the men of the Nile Valley. -God promised Moses to lead his people “to a land flowing with milk and honey”. -It is said that Heracles had thrown himself with such a thirst on the breast of Hera, that a splash of milk came out and formed the Milky Way. -For Hindus, the world was created from the churning of the ocean of milk. -Breastfeeding is very present in mythology. Zeus was nursed by the goat Amalthea, and the two founders of Rome, Romulus and Remus were fed by a wolf.

But what is milk in fact and what is it made of? Milk is a biological fluid usually witishly colored produced by female mammals. Lactation (ability to produce milk) is a property possessed only by mammals. The primary function of milk is to feed offsprings until they get weaned (able to digest other foods, milk is a food that is very easily digested) and to support them during the first days of their life thanks to it’s extremely high nutritive properties. Now, let’s go further into the understanding of milk composition. Goat’s milk density varies between 1.027g/L and 1.035g/L. Goat’s milk has a pH slightly acid that varies between 6.4 and 6.8, this is due to a greater presence of hydroxyl groups than amino groups in the milk. It’s biological composition can be separated in two big parts: the liquid part (87%) and the solid part (13%).

But how is produced this wonderful beverage? First, let’s explore the amazing world of control networks in the goat’s body. Four elements in the goat control and allow it’s milk production: the pituitary gland, the adrenal glands, the thyroid gland and the foetus & the sexual organs when the goat is pregnant. But the nervous system and the blood supply are essential to operate all the process. The pituitary gland: is divided in two parts, the posterior lobe, that stores hormones produced by the brain and the releases them and the atenrior lobe, that produces it’s own hormones. ADH (antidiuretic hormone): helps the kidneys to return water to the organism. This is important in lactation to preserve water for milk production. Octocin: il acts on the muscle cels of the alveoli (where milk is produced) causing them to contract to push milk into the ducts. STH (Somatotropic Hormone): It causes the growth of all body cells (including alveoli) and has a direct effect on the initiation of lactation. TSH (Thyroid stimulating hormone): acts on the tyroid gland to produce thyroxine. It influences lactation duration. ACTH (Adrenocorticotropin): Stimulates the adrenal gland to produce cortical hormones. ACTH production is stimulated by sucking reflex. FSH (Follicle stimulating hormone): acts on the ovaries to produce estrogen wich is necessary for alveoli growth and it’s duct system. LH (Luteinizing hormone): it stimulates ovaries to produce estrogen and progesterone wich contribute to the developement of mammary glands. LTH (Luteotropic Hormone): has a direct influence on mammary gland growth, the initiation of lactation and the maintenance of milk secretion. Prolactin: necessary for the launching of lactation.

The tyroid gland: it has two lobes at each side of the trachea. It is stimulated by the TSH seen before. THC coming from the pituitary gland Production of thyroid hormones, very important to maintain lactation.

The adrenal glands: they produce hormones essential to life process and are located at the back of the goat near to the spine. ACTH produced by the pituitary gland following a sucking stimulus. Production of cortical hormones, necessary for milk secretion. But we should’nt forget that other parts of the body are required to complete the process: -During pregnancy, the fœtus produces estrogen and the ovary progesterone, in consequence, mammary tissues grow. When progesterone and estrogen levels are high, the brain produces PIF ( prolactin inhibitory factor) that inhibits the pituitary gland to release prolactin, there is no lactation. When the mother gives birth, her progesterone and estrogen levels drop, PIF stops being produced ans prolactin is released, lactation can begin. -The nervous system allows the releasing of some hormones by sucking stimulation. -Of cource, no hormone transmission without the blood supply system that carry hormones all over the body but that also carry some nutrients to the mammary glands to allow lactation.

The fœtus & the sexual organs: This are two very important sources of hormones that permit to regulate goat’s milk producting period. The fœtus produces estrogen and the ovary produces progesterone. The mamary tissue grows but lactation is inhibited. When the goat gives birth, the estrogen and progesterone levels drop. The pituitary gland releases prolactin that will provoque lactation.