The importance of small ruminants to the dairy industry has increased in recent years, especially in developing countries, where it has a high economic and social impact. Interestingly and despite the fact that the mammary gland is the specialised milk production organ, very few authors studied the modifications occurring in the mammary gland through the lactation period in production animals, particularly in the small ruminants, sheep (Ovis aries) and goat (Capra hircus). Nevertheless, understanding the different mammary gland patterns throughout lactation is essential to improve dairy production. In addition, associating these patterns with different milking frequencies, lactation number or different diets is also of high importance, directly affecting the dairy industry. The mammary gland is commonly composed of parenchyma and stroma, which includes the ductal system, with individual proportions of each changing during the different periods and yields in a lactation cycle. Indeed, during late gestation, as well as during early to mid-lactation, mammary gland expansion occurs, with an increase in the number of epithelial cells and lumen area, which leads to increment of the parenchyma tissue, as well as a reduction of stroma, corresponding macroscopically to the increase in mammary gland volume. Throughout late lactation, the mammary gland volume decreases owing to the regression of the secretory structure. In general, common mammary gland patterns have been shown for both goats and sheep throughout the several lactation stages, although the number of studies is limited. The main objective of this manuscript is to review the colostrogenesis and lactogenesis processes as well as to highlight the mammary gland morphological patterns underlying milk production during the lactation cycle for small ruminants, and to describe potential differences between goats and sheep, hence contributing to a better description of mammary gland development during lactation for these two poorly studied species.

The anomalies which occur during the development of the avian organisms result in structural and functional abnormalities. In the present review, the majority of surveyed reports on developmental malformations are related to wild birds and secondarily to poultry birds. Regarding their etiology, spontaneous and genetic aberrations were surveyed. The great part of malformations refers to the skeletal system. Among them, the most frequently occurring types were beak deformities, absent, supernumerary or deformed limbs. Embryonic conjoined duplications were also recorded. Anomalies of structure, number and coloration of feather were highlighted. Abnormalities of the heart and ocular malformations were compiled. Also, malformations of the gastrointestinal as well as of the uro-genital system were collected. The malformations which were briefly described constitute a database which could be a useful tool for the further study of embryology, experimental toxicology and teratology of animals