{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/32980"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/32980","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Effects of varying energy intakes on mammary growth and development in prepubertal heifers","abstract":"Rapid rearing of dairy heifers during late prepuberty has been linked to impairments in mammary development and reductions in milk yield. Our objective was to determine how varying energy intakes between 2 and 14 wk of age affect mammary parenchymal development. At 2 wk of age, Holstein calves were assigned to 1 of 4 treatments (HH, HL, LH, and LL) with 2 levels of energy intake (High or Low) and 2 periods of growth (2 to 8 and 8 to 14 wk of age). At 14 wk, parenchyma at the stromal interface, mid-gland, and above the cistern were collected, fixed, and embedded in paraffin. Digital images of stained sections were used to determine tissue composition (% epithelium, lumen, and stroma). Immunochemistry revealed estrogen receptor (ER) and Ki67 (nuclear proliferation antigen) positive cells, type IV collagen, fibronectin (FN), and laminin. Images representing 4 increasing grades were used to quantify ECM protein deposition. Lumenal and stromal areas were 3.5 ± 1.4% higher (p<0.01) and 4.0 ± 1.7% lower (p<0.01), respectively, in HH and HL heifers. Ki67 labeling in terminal ductular units and subtending ducts was 2.1 ± 0.8% (p<0.01) and 1.4 ± 0.7% (p<0.05) lower for the same feeding level combination. FN deposition was also increased (p<0.05) in HH and HL heifers. High rates of gain between 2 and 14 wk of age resulted in greater lumenal area and reduced cell proliferation in mammary parenchyma at 14 wk of age. Changes in FN deposition could have mediated growth differences.","abstract_html":"Rapid rearing of dairy heifers during late prepuberty has been linked to impairments in mammary development and reductions in milk yield. Our objective was to determine how varying energy intakes between 2 and 14 wk of age affect mammary parenchymal development. At 2 wk of age, Holstein calves were assigned to 1 of 4 treatments (HH, HL, LH, and LL) with 2 levels of energy intake (High or Low) and 2 periods of growth (2 to 8 and 8 to 14 wk of age). At 14 wk, parenchyma at the stromal interface, mid-gland, and above the cistern were collected, fixed, and embedded in paraffin. Digital images of stained sections were used to determine tissue composition (% epithelium, lumen, and stroma). Immunochemistry revealed estrogen receptor (ER) and Ki67 (nuclear proliferation antigen) positive cells, type IV collagen, fibronectin (FN), and laminin. Images representing 4 increasing grades were used to quantify ECM protein deposition. Lumenal and stromal areas were 3.5 ± 1.4% higher (p&lt;0.01) and 4.0 ± 1.7% lower (p&lt;0.01), respectively, in HH and HL heifers. Ki67 labeling in terminal ductular units and subtending ducts was 2.1 ± 0.8% (p&lt;0.01) and 1.4 ± 0.7% (p&lt;0.05) lower for the same feeding level combination. FN deposition was also increased (p&lt;0.05) in HH and HL heifers. High rates of gain between 2 and 14 wk of age resulted in greater lumenal area and reduced cell proliferation in mammary parenchyma at 14 wk of age. Changes in FN deposition could have mediated growth differences.","abstract_has_math":false,"creators":["Forrest, James Walter"],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Dairy Science","degree_department":"Dairy Science","school":null,"contributors":[],"advisors":[],"committee_chairs":["Akers, Robert Michael"],"committee_members":["Howard, Rick Dale","Pearson, Ronald E."],"year":2003,"date_issued":"2003-05-16","date_published":"2003-05-16","updated_at":"2026-07-22T22:20:11Z","subjects":["estrogen receptor","heifers","mammary","extracellular matrix","Nutrition"],"languages":[],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-05192003-133446"],"render_values":[{"text":"etd-05192003-133446","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/32980","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Akers, Robert Michael"]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Howard, Rick Dale","Pearson, Ronald E."]},{"key":"dc:contributor.department","label":"Department","values":["Dairy Science"]},{"key":"dc:creator","label":"Author","values":["Forrest, James Walter"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2014-03-14T20:37:34Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2014-03-14T20:37:34Z","2003-06-09"]},{"key":"dc:date.issued","label":"Date","values":["2003-05-16"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Dairy Science"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["estrogen receptor","heifers","mammary","extracellular matrix","Nutrition"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-05192003-133446"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/32980"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Rapid rearing of dairy heifers during late prepuberty has been linked to impairments in mammary development and reductions in milk yield. Our objective was to determine how varying energy intakes between 2 and 14 wk of age affect mammary parenchymal development. At 2 wk of age, Holstein calves were assigned to 1 of 4 treatments (HH, HL, LH, and LL) with 2 levels of energy intake (High or Low) and 2 periods of growth (2 to 8 and 8 to 14 wk of age). At 14 wk, parenchyma at the stromal interface, mid-gland, and above the cistern were collected, fixed, and embedded in paraffin. Digital images of stained sections were used to determine tissue composition (% epithelium, lumen, and stroma). Immunochemistry revealed estrogen receptor (ER) and Ki67 (nuclear proliferation antigen) positive cells, type IV collagen, fibronectin (FN), and laminin. Images representing 4 increasing grades were used to quantify ECM protein deposition. Lumenal and stromal areas were 3.5 ± 1.4% higher (p<0.01) and 4.0 ± 1.7% lower (p<0.01), respectively, in HH and HL heifers. Ki67 labeling in terminal ductular units and subtending ducts was 2.1 ± 0.8% (p<0.01) and 1.4 ± 0.7% (p<0.05) lower for the same feeding level combination. FN deposition was also increased (p<0.05) in HH and HL heifers. High rates of gain between 2 and 14 wk of age resulted in greater lumenal area and reduced cell proliferation in mammary parenchyma at 14 wk of age. Changes in FN deposition could have mediated growth differences."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:title","label":"Title","values":["Effects of varying energy intakes on mammary growth and development in prepubertal heifers"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Akers, Robert Michael"],"dc:contributor.committeemember":["Howard, Rick Dale","Pearson, Ronald E."],"dc:contributor.department":["Dairy Science"],"dc:creator":["Forrest, James Walter"],"dc:date.accessioned":["2014-03-14T20:37:34Z"],"dc:date.available":["2014-03-14T20:37:34Z","2003-06-09"],"dc:date.issued":["2003-05-16"],"dc:description.abstract":["Rapid rearing of dairy heifers during late prepuberty has been linked to impairments in mammary development and reductions in milk yield. Our objective was to determine how varying energy intakes between 2 and 14 wk of age affect mammary parenchymal development. At 2 wk of age, Holstein calves were assigned to 1 of 4 treatments (HH, HL, LH, and LL) with 2 levels of energy intake (High or Low) and 2 periods of growth (2 to 8 and 8 to 14 wk of age). At 14 wk, parenchyma at the stromal interface, mid-gland, and above the cistern were collected, fixed, and embedded in paraffin. Digital images of stained sections were used to determine tissue composition (% epithelium, lumen, and stroma). Immunochemistry revealed estrogen receptor (ER) and Ki67 (nuclear proliferation antigen) positive cells, type IV collagen, fibronectin (FN), and laminin. Images representing 4 increasing grades were used to quantify ECM protein deposition. Lumenal and stromal areas were 3.5 ± 1.4% higher (p<0.01) and 4.0 ± 1.7% lower (p<0.01), respectively, in HH and HL heifers. Ki67 labeling in terminal ductular units and subtending ducts was 2.1 ± 0.8% (p<0.01) and 1.4 ± 0.7% (p<0.05) lower for the same feeding level combination. FN deposition was also increased (p<0.05) in HH and HL heifers. High rates of gain between 2 and 14 wk of age resulted in greater lumenal area and reduced cell proliferation in mammary parenchyma at 14 wk of age. Changes in FN deposition could have mediated growth differences."],"dc:description.degree":["Master of Science"],"dc:identifier.other":["etd-05192003-133446"],"dc:identifier.uri":["http://hdl.handle.net/10919/32980"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["estrogen receptor","heifers","mammary","extracellular matrix","Nutrition"],"dc:title":["Effects of varying energy intakes on mammary growth and development in prepubertal heifers"],"dc:type":["Thesis"],"thesis:degree_discipline":["Dairy Science"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:20:11Z"}