Continuous lactation effects on mammary remodeling during late gestation and lactation in dairy goats

Abstract

The present study aimed to 1) elucidate whether continuous milking during late gestation in dairy goats negatively affects mammary remodeling and hence milk production in the subsequent lactation, and 2) identify the regulatory factors responsible for changes in cell turnover and angiogenesis in the continuously lactating mammary gland. Nine multiparous dairy goats were used. One udder half was dried off approximately 9 wk prepartum (normal lactation; NL), and the other udder half of the same goat was milked continuously (continuous lactation; CL) until parturition or until the half-udder milk yields had dropped to below 50 g/d. Mammary biopsies were obtained from each udder half just before the NL gland was dried off (before dry period), within the first 2 wk after drying-off (early dry period, samples available only for NL glands), in the mid dry period, within the last 2 wk before parturition (late dry period), and at d 1 (the day of parturition), 3, 10, 60, and 180 of lactation. Mammary morphology was characterized in biopsies by quantitative histology, and cell turnover was determined by immunohistochemistry (terminal deoxynucleotidyl transferase dUTP nick end labeling and Ki-67). Transcription of genes encoding factors involved in mammary epithelial cell (MEC) turnover and vascular function was quantified by quantitative reverse transcription PCR. Results demonstrated that omitting the dry period was possible in goats but was not as easy as claimed before. Renewal of MEC was suppressed in CL glands, which resulted in a smaller MEC population in the subsequent lactation. At the time of parturition (and throughout lactation), the mammary glands subjected to CL had smaller alveoli, more fully differentiated MEC, and a substantially larger capillary fraction compared with NL glands. The continuously lactating gland thus resembled a normally lactating gland in an advanced stage of lactation. None of the studied genomic factors could account for these treatment differences. The described characteristics in CL glands compared with NL glands indicated a gland maintained in lactation for a longer period.

Alpha-ketoglutarate enhances milk protein synthesis by porcine mammary epithelial cells

“…It has been suggested that the milk yield of sows is influenced by various factors such as genotype, nutrition (Quesnel et al 2009), physical activity and sucking stimulation (Malmkvist et al 2012). During lactation, mammary epithelial cells undergo morphological and functional changes under the influence of hormones (such as prolactin) and many other factors [such as amino acid provision, blood flow, and endoplasmic reticulum stress (ERS)] (Noble and Hurley 1999;Baldi et al 2002;Boutinaud et al 2004;Rezaei et al 2013;Safayi et al 2010). The number of mammary cells and the amount of nutrients available to those mammary cells are the main determinants of milk production (Kim and Wu 2009).…”

Erken ve Geç Laktasyon Periyodunun Keçilerde Plazma Oksidan/Antioksidan Dengesi Üzerindeki Etkileri

“…It has been reported that differences can be observed in the level of oxidative stress with respect to the stages of lactation period 2,4 . The changes occurring at the composition of the milk in lactation period are resulted from the various factors such as epithelial cell proliferations, secretion activity, supplying of the nutrients and removing of the metabolic wastes by means of the blood 5,6 . General knowledge about oxidative stress relatedmetabolic disorders increases, and the pathologic effects of these disorders generally are associated with the free radical molecules [7][8][9] .…”

Mucin 1 Aberrantly Expresses in Goat Mammary Carcinoma

“…Histomorphological features of poorly differentiated MEC can be observed by visualizing cellular morphology wherein the cells are smaller in size, absence of fat vacuole inside the cytoplasm and reduced cytoplasmic area. 17,18 In mammary carcinomas, aberrant expression of MUC1 was seen. MUC1 was located in the nuclei plus cytoplasm of majority of the MEC ( Figure 4C).…”