Influence of prepubertal dietary regimen on mammary growth of Holstein heifers

• Published in: Journal of dairy science Vol. 78; no. 12; p. 2709
• Main Authors: Capuco, A V, Smith, J J, Waldo, D R, Rexroad, Jr, C E
• Format: Journal Article
• Language: English
• Published: United States 01-12-1995
• Subjects: Adipocytes - cytology; Animals; Body Weight; Cattle - physiology; Cell Count; Diet; Epithelial Cells; Female; Growth Hormone - blood; Insulin-Like Growth Factor I - metabolism; Lactation; Mammary Glands, Animal - cytology; Mammary Glands, Animal - growth & development; Medicago sativa; Prolactin - blood; Random Allocation; Sexual Maturation; Silage; Zea mays
• ISSN: 0022-0302
• DOI: 10.3168/jds.S0022-0302(95)76902-8

One hundred-sixteen Holstein heifers (mean BW, 175 kg) were randomly assigned to diets of alfalfa silage or corn silage and were fed to gain approximately 725 or 950 g/d in order to study the influence of prepubertal diet and rate of gain on mammary growth and milk production. Blood was collected before puberty for hormone determination, and 8 heifers per group were killed at puberty for evaluation of tissue variables. Serum growth hormone was reduced, and IGF-I was increased, in the group of heifers reared at a high rate of gain on the corn silage diet. Accompanying the decline in growth hormone, total mammary parenchymal DNA and RNA was reduced in heifers reared at a high rate of gain on the corn silage diet. Mammary parenchyma in heifers of the latter group contained a greater volume of adipocytes and a lower volume of epithelial cells than did mammary parenchyma in heifers of other groups. Data are consistent with previous investigations that showed a deleterious effect of prepubertal rapid weight gain on mammogenesis when accompanied by excess body fat deposition. However, this effect did not cause a decline in subsequent milk production.