Estrogen-dependent responses of the mammary fat pad in prepubertal dairy heifers

Meyer, M. J.; Capuco, Anthony; Boisclair, YR; Amburgh, Mike Van

doi:10.1677/joe.1.06883

Cited by 28 publications

(37 citation statements)

References 36 publications

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“…Conversely, the numerically lower value for CTLS gilts compared with CTL0 gilts was surprising. Consistent with our current observations of increased DNA in mammary parenchyma and reduced number of ERa-positive mammary epithelial cells in GEN gilts, Capuco and colleagues (Capuco et al, 2002;Meyer et al, 2006) noted that exogenous estrogen stimulates the in vivo proliferation of mammary cells in dairy heifers while decreasing expression of ERa.…”

Section: Discussionsupporting

confidence: 89%

Dietary genistein stimulates mammary hyperplasia in gilts

Farmer

Palin

Gilani

et al. 2010

Animal

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The possible role of the phytoestrogen genistein on prepubertal development of mammary glands, hormonal status and bone resorption was investigated in gilts. Forty-five gilts were fed a control diet containing soya (CTLS, n 5 15), a control diet without soya (CTL0, n 5 15) or the CTLS diet supplemented with 2.3 g of genistein daily (GEN, n 5 15) from 90 days of age until slaughter (day 183 6 1). Both basal diets were isonitrogenous and isocaloric. Jugular blood samples were obtained on days 89 and 176 to determine concentrations of isoflavone metabolites (on day 176 only), prolactin, estradiol, progesterone, insulin-like growth factor 1 (IGF1), and N-telopeptide of type I collagen (NTx; on day 176 only). At slaughter, mammary glands were excised, parenchymal and extraparenchymal tissues were dissected, and composition of parenchymal tissue (protein, fat, dry matter (DM), DNA) was determined. Histochemical analyses of mammary parenchyma were performed. Dietary genistein increased parenchymal protein (P , 0.05) while decreasing DM (P , 0.05) and tending to lower fat content compared with the CTLS, but not the CTL0, diet. There was more parenchymal DNA (1.26 v. 0.92 mg/g, P , 0.05) in GEN than CTLS gilts, likely reflecting an increase in the quantity of mammary epithelial cells. Circulating concentrations of genistein were increased in GEN gilts (P , 0.001) but concentrations of hormones or NTx (indicator of bone collagen resorption) were not affected by GEN (P . 0.1). Percentage of estradiol receptor alpha (ERa)-positive epithelial cells was lower (P , 0.05) in GEN than CTLS gilts, whereas 5-bromo-2 0 -deoxyuridine labeling index was unaltered (P . 0.1). Transcript levels for ERa, ERb, IGF1, epidermal growth factor (EGF), epidermal growth factor receptor and transforming growth factor alpha were not altered by treatments. Supplementation of the diet with genistein during the growing phase in gilts, therefore, led to hyperplasia of mammary parenchymal tissue after puberty; yet, even though circulating genistein was increased, this was not accompanied by changes in mammary expression of selected genes or circulating hormone levels.

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Section: Discussionsupporting

confidence: 89%

Dietary genistein stimulates mammary hyperplasia in gilts

Farmer

Palin

Gilani

et al. 2010

Animal

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“…This may reflect the relative short interval (30 days) between ovariectomy and tissue collection. In agreement with our observations, Meyer et al (2006a) did not find an effect of ovariectomy on MEC proliferation when the heifers were ovariectomized at 4.6 months and samples harvested after 33 days.…”

Section: Discussionsupporting

confidence: 93%

“…However, gene expression in MFP was not affected by ovariectomy. Others have also reported that relative mRNA expression of estrogen-responsive genes in MFP was similar in both OVX and INT heifers (Meyer et al, 2006a).…”

Section: Discussionmentioning

confidence: 83%

“…However, the reduction in circulating concentration of estradiol in response to ovariectomy in prepubertal heifers was only 0.1 pg/ml (Purup et al, 1993), which appears inadequate to elicit the dramatic reduction in parenchymal growth that was noted in that study. Moreover, literature shows that a daily dose of , 0.1 mg/kg body weight (BW) estradiol is required to elicit positive responses in mammary epithelial cell (MEC) proliferation (Woodward et al, 1993;Capuco et al, 2002;Meyer et al, 2006a). On the other hand, a large increase in the expression of estrogen receptor-a (ERa) was noted in conjunction with a significant reduction in MEC proliferation in older ovariectomized heifers (Berry et al, 2003a).…”

Section: Introductionmentioning

confidence: 99%

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Effect of staged ovariectomy on measures of mammary growth and development in prepubertal dairy heifers

Velayudhan

Huderson

McGilliard

et al. 2012

Animal

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Previous studies in prepubertal heifers suggest that the magnitude of reduction in mammary parenchymal growth in response to ovariectomy varies with the age at which surgery is performed. We hypothesized that ovarian secretions are essential for initiating mammary development but not required to maintain allometric mammary growth in prepubertal dairy heifers. The objectives of this study were to determine the effect of staged ovariectomy during the prepubertal period on mammary growth and tissue composition and the expression of selected genes. Prepubertal Holstein heifers at 2, 3 or 4 months of age were randomly assigned to one of two treatments, ovariectomized (OVX; n 5 12) or sham operated (INT; n 5 12). Mammary parenchyma (PAR) and fat pad (MFP) were harvested 30 days after surgery. Proximate composition of PAR and MFP (DNA, protein and lipid) as well as expression of the selected estrogen-responsive genes stanniocalcin1 (STC1), tissue factor pathway inhibitor precursor (TFPI) and proliferating cell nuclear antigen (PCNA) were determined in PAR and MFP by quantitative real-time PCR. The relative amount of epithelium and proportion of epithelia cell nuclei expressing the proliferation marker Ki67 were determined by histological and immunohistochemical analyses, respectively. MFP mass was not impacted by treatment but was decreased with age as was lipid content and concentration (P < 0.01). The mass of mammary PAR was reduced in OVX and increased with age (P < 0.01). Parenchymal tissue tended to have less total DNA, protein and lipid in OVX heifers. Parenchymal tissue concentrations of protein and DNA were increased with age and there was an age 3 treatment interaction. Treatment had no effect on either the Ki67 labeling index or percent epithelial area. The relative abundances of STC1, TFPI and PCNA mRNA in PAR were reduced in OVX. We did not find a significant impact of ovariectomy on mRNA expression when surgery was performed at 2 months compared with surgery at 3 or 4 months of age. However, having nearly undetectable PAR in two heifers ovariectomized at the earliest period (2 months of age) suggests that early ovariectomy is especially detrimental to subsequent parenchymal development.

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“…This argues against isometric growth of PAR (with respect to body mass) and favors an allometric pattern of mammary growth in young heifers. To date, it is the general belief that an increased level of nutrient intake during the first 2 mo of age does not impair PAR growth in heifers, and may actually enhance growth (Brown et al, 2005a;Meyer et al, 2006a;Daniels et al, 2009). More research is needed on the effects of diet on PAR accretion in young heifers.…”

Section: Introductionmentioning

confidence: 99%

Examination of weekly mammary parenchymal area by ultrasound, mammary mass, and composition in Holstein heifers reared on 1 of 3 diets from birth to 2 months of age

Esselburn

Hill²,

Bateman³

et al. 2015

Journal of Dairy Science

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Monitoring in vivo growth of mammary parenchyma (PAR) has historically been difficult, necessitating slaughter studies to measure PAR quantity. Advances in ultrasound (US) technology warrant revisiting its use as a noninvasive tool to monitor PAR growth in vivo. The level of nutrient intake during the first 2mo of life may affect measures of mammary growth and composition. Objectives were to examine the utility of US as an in vivo tool to quantify PAR cross-sectional area in Holstein heifers reared on 1 of 3 diets from birth to 2mo of age, assessing potential dietary effects; assess the relationships between weekly US measurements, teat length, manual palpation of PAR scores, and PAR mass at 2mo of age; and examine mammary composition in experimental animals. Holstein heifers (n=24; 41±1kg of initial body weight) from a single farm were randomly assigned to 1 of 3 milk replacers that differed in source and amount of fat. Milk replacer was fed at 660g of dry matter/d until weaning at 42 d. Heifers had ad libitum access to a common calf starter (20% crude protein) and water for the duration of the 56-d trial. Teat length and palpation scores were obtained weekly. A real-time B-mode US with a 7.5-MHz convex probe was used to examine 2-dimensional PAR area in all 4 glands of heifers once weekly from 2 to 3 d of age to harvest at 56 d. The left front and left rear glands were also examined by US 24h postharvest to validate final US measurements, and then bisected to produce a sagittal plane view of PAR for comparison with US images. Mass and composition of mammary gland tissue were determined at 8 wk using standard methodology. Over the course of this 8-wk trial, average teat length increased from 11 to 17mm. The PAR area started small (6.6±3.2mm(2) per gland) and increased to 42.1±2.5mm(2) per gland by the end of the trial. As anticipated, based on measurements obtained at slaughter, US measurements were more related to amount of PAR (r=0.74) than either teat length (r=0.34) or palpation scoring (r=0.63). Importantly, US is quantitative, whereas palpation scoring is subjective. Diet did not affect mass or composition of PAR in young heifers; total udder PAR mass averaged 1.40±0.80g. In conclusion, we showed that in heifers younger than 2mo of age, obtaining weekly PAR measurements via ultrasound is an effective quantitative tool for measuring changes in PAR area in vivo. Future studies may incorporate and expand upon the methods developed here to determine what quantitative evaluation of PAR in young heifers can reveal about milk production capacity.

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Estrogen-dependent responses of the mammary fat pad in prepubertal dairy heifers

Cited by 28 publications

References 36 publications

Dietary genistein stimulates mammary hyperplasia in gilts

Dietary genistein stimulates mammary hyperplasia in gilts

Effect of staged ovariectomy on measures of mammary growth and development in prepubertal dairy heifers

Examination of weekly mammary parenchymal area by ultrasound, mammary mass, and composition in Holstein heifers reared on 1 of 3 diets from birth to 2 months of age

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