Effects of Controlled Compensatory Growth on Mammary Gland Development and Lactation in Rats

Abstract

The objective of this study was to examine the effect of compensatory growth nutritional regimen on mammary gland growth and lactation. One hundred twenty-two Sprague Dawley female rats (35 days of age) were randomly assigned to either a control or a stair-step compensatory nutrition (SSCN) feeding regimen or an alternating 2-2-3-3-week schedule beginning with 40% energy restriction for 2 weeks followed by re-alimentation (control diet) for 2 weeks. Pup weight gain and milk yield were improved 8% and 8 to 15%, respectively, by the SSCN regimen. The gene expression of ß-casein was 2.3-fold greater in the SSCN group than in the control group during early lactation, but they were greater at all stages of the second lactation. The gene expression of insulin-like growth factor-I was 40% lower in the SSCN group than in the control group during early lactation of the second lactation, but during late lactation it was 80% greater than in the control group. The concentration of serum corticosterone tended to be higher in the SSCN group during the late stage of the first lactation. These results suggest that the stair-step compensatory nutrition regimen improves lactation performance and persistency by modulation of cell differentiation and apoptotic cell death.

Limits to sustained energy intake. XVII. Lactation performance in MF1 mice is not programmed by fetal number during pregnancy

“…They found that both prepartum and postpartum mammogenesis were reduced in relation to the number of placentas removed. A strong impact of pregnancy is also implied by studies demonstrating that nutritional events during hormone-sensitive growth phases, especially during late gestation, can significantly affect mammary development and subsequent lactation performance (Kim et al, 1998;Moon and Park, 1999;Moon and Park, 2002) in dairy cattle, beef heifers and female rats. These improvements in performance have been linked to increased cell proliferation with concurrent elevations in gene expression of key genes involved in cell proliferation and differentiation.…”

Role of compensatory mammary growth in epigenetic control of gene expression

“…The expression of the β‐casein gene is higher (40–74%) in mammary tissues during late gestation from heifers reared on a compensatory nutrition regimen than in those from conventionally raised heifers. In early lactating mammary tissues from rats on compensatory nutrition, there is also a pronounced increase in β‐casein message, amounting to 132% and 48% for first and second lactation cycles, respectively (3). The α‐ and γ‐casein and whey acidic protein mRNA are also higher in lactating mammary tissues from rats reared on a compensatory nutrition regimen (21).…”

“…Finally, insulin-like growth factor-I (IGF-I), which regulates mammary gland development through both promotion of cell cycle progression and inhibition of apoptosis (29), is lower in mammary tissues from the compensatory group than in those from the control group during early lactation and higher during late lactation (3). The expression of IGF-I during early lactation may be a possible negative factor for milk production in rats, and the compensatory-mediated increase in IGF-I mRNA during late lactation may have a suppressing effect on apoptosis of mammary cells.…”

Impact of diet deprivation and subsequent over-allowance during prepuberty. Part 2. Effects on mammary gland development and lactation performance of sows1

“…The use of compensatory feeding regimens to stimulate mammary development and lactation potential is an avenue that has received quite a bit of interest in rodents and heifers. In rats, a stair-step nutrition model inducing compensatory growth during peripuberty only or during peripuberty and gestation (Moon and Park, 2002) improves lactation performance by modulation of mammary cell differentiation. These changes were accompanied by increases in casein β (CSN2; Moon and Park, 2002) and ornithine decarbolyxase (ODC1; Kim et al, 1998) mRNA abundance in mammary tissues.…”

“…In rats, a stair-step nutrition model inducing compensatory growth during peripuberty only or during peripuberty and gestation (Moon and Park, 2002) improves lactation performance by modulation of mammary cell differentiation. These changes were accompanied by increases in casein β (CSN2; Moon and Park, 2002) and ornithine decarbolyxase (ODC1; Kim et al, 1998) mRNA abundance in mammary tissues. In heifers, nutritionally directed compensatory growth increased milk yield along with CSN2 gene expression in mammary tissue in late gestation and lactation Ford and Park, 2001).…”