Growth and development of the mammary glands of livestock: A veritable barnyard of opportunities

Rowson, A.R.; Daniels, K.M.; Ellis, S.E.; Hovey, Russell C.

doi:10.1016/j.semcdb.2012.03.018

Cited by 69 publications

(76 citation statements)

References 110 publications

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“…When a heifer is born, a rudimentary mammary ductal system is present (reviewed in Rowson et al, 2012). The duct system extends from the teat cistern to the gland cistern and ends with the epithelial ducts.…”

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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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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“…The global economic value of buffalo is tremendous and ultimately hinges on its mammary glands, either through its capacity to provide dairy products or because of its growth and production of milk which underlies successful animal production, welfare, and survival [6]. Milk yield and shape of lactation curve are determined by the number of mammary secretory cells and the secretory activity per cell [7].…”

Section: Introductionmentioning

confidence: 99%

Morphogenesis of Mammary Glands in Buffalo (Bubalus bubalis)

Challana

Gupta

Bansal

et al. 2014

Anatomy Research International

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The present research was elucidated on the morphogenesis of mammary gland of buffalo during prenatal development. Total of 16 foetuses ranging from 1.2 cm (34 days) to 108 cm CVRL (curved crown rump length) (317 days) were used for study. The study revealed that mammary line was first observed at 1.2 cm CVRL (34 days), mammary hillock at 1.7 cm (37 days), and mammary bud at 2.6 cm CVRL (41 days) foetuses. Epidermal cone was found at 6.7 cm CVRL (58 days) whereas primary and secondary ducts were observed at 7.4 cm CVRL (62 days) and 15 cm CVRL (96 days), respectively. Connective tissue whorls were reported at 18.2 cm CVRL (110 days) and internal elastic lamina and muscle layers at 24.1 cm CVRL (129 days). Lobules were observed at 29.3 cm CVRL (140 days), rosette of furstenberg at 39.5 cm CVRL (163 days), and keratin plug at 45.5 cm CVRL (176 days) foetus. Primordia of sweat and sebaceous glands around hair follicle were seen at 21.2 cm CVRL (122 days) of foetal life. Differentiation of all the skin layers along with cornification was observed at 69 cm (229 days) in group III foetuses.

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“…During elongation of the ductal network around the onset of puberty, activation of the hypothalamic–pituitary–gonadal axis leads to increased epithelial proliferation at the termini of ducts, either as terminal end bud ( TEB ) structures characteristically present at the leading edge of the mammary ducts in rodents, pigs, and humans (Hovey et al, 2002; Rowson et al, 2012) or as a peripheral zone of mitosis within the more complex terminal ductal lobular unit structures found within the MG of female ruminants such as heifers and ewe lambs (Ellis and Capuco, 2002). The ability of E to promote TEB formation in rodents is particularly pronounced: depending on the dose and route of exposure, the mitotic rate in epithelial cells following E exposure increases from <1 to >50% in a matter of days (Daniel et al, 1987).…”

Section: The Case For Estrogens As Primary Regulators Of Mg Developmentmentioning

confidence: 99%

Mammary gland development—It’s not just about estrogen

Berryhill

Trott

Hovey

2016

Journal of Dairy Science

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The mammary gland (MG) is one of a few organs that undergoes most of its growth after birth. Much of this development occurs concurrently with specific reproductive states, such that the ultimate goal of milk synthesis and secretion is coordinated with the nutritional requirements of the neonate. Central to the reproductive–MG axis is its endocrine regulation, and pivotal to this regulation is the ovarian secretion of estrogen (E). Indeed, it is widely accepted that estrogens are essential for growth of the MG to occur, both for ductal elongation during puberty and for alveolar development during gestation. As the factors regulating MG development continually come to light from the fields of developmental biology, lactation physiology, and breast cancer research, a growing body of evidence serves as a reminder that the MG are not as exclusively dependent on estrogens as might have been thought. The objective of this review is to summarize the state of information regarding our understanding of how estrogen (E) has been implicated as the key regulator of MG development, and to highlight some of the alternative E-independent mechanisms that have been discovered. In particular, we review our findings that dietary trans-10,cis-12 conjugated linoleic acid promotes ductal elongation and that the combination of progesterone (P) and prolactin (PRL) can stimulate branching morphogenesis in the absence of E. Ultimately, these examples stand as a healthy challenge to the question of just how important estrogens are for MG development. Answers to this question, in turn, increase our understanding of MG development across all mammals and the ways in which it can affect milk production.

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Growth and development of the mammary glands of livestock: A veritable barnyard of opportunities

Cited by 69 publications

References 110 publications

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

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

Morphogenesis of Mammary Glands in Buffalo (Bubalus bubalis)

Mammary gland development—It’s not just about estrogen

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