Gastrointestinal parasite control during prepuberty improves mammary parenchyma development in Holstein heifers

Abstract

a b s t r a c tParasitism during development impairs normal growth and delays the onset of puberty through altered hormone profiles, including insulin-like growth factor one (IGF-1). As mammary gland development during prepuberty is strongly dependent on IGF-1, we determined if antiparasitic treatment during this stage of growth improved mammary gland development. One group of Holstein heifers was treated monthly, rotationally with antiparasitic drugs from birth to 70 weeks of age, a second group was untreated. Treated heifer calves had between 56% and 65% less EPG counts than untreated ones. Presence of Ostertagia, Cooperia, Haemonchus and Trichostrongylus was demonstrated. Treatment effectively advanced the onset of puberty and increased IGF-1 levels. At 20, 30, 40 and 70 weeks of age biopsies from the mammary gland were taken and histological sections were prepared and stained with hematoxylin-eosin. Pictures were analyzed to compare parenchyma area in relation to total mammary tissue between groups. Mammary samples from treated heifers had higher ratios of parenchyma/total area than untreated ones. As mammary development during prepuberty is crucial for mammary performance during lactation, these results add new evidence to the importance of gastrointestinal parasite control in heifers.

Cellular proliferation rate and insulin-like growth factor binding protein (IGFBP)-2 and IGFBP-3 and estradiol receptor alpha expression in the mammary gland of dairy heifers naturally infected with gastrointestinal nematodes during development

“…The T heifers received monthly, from birth to 18 mo of age, different anthelmintic drugs to minimize parasite burden avoiding drug resistance generation. The following drugs were used: ivermectin (0.63 mg/ kg), fenbendazol (7.5 mg/kg), and levamisol (10 mg/ kg; Perri et al, 2013).…”

“…At 20, 30, 40, and 70 wk of age, mammary biopsies were taken from 6 heifers in each group (Perri et al, 2013). Briefly, heifers were sedated with 1% acepromazine (0.15 mg/kg, Holliday Scott S.A., Buenos Aires, Argentina) and immobilized in a supine position.…”

“…Particularly, IGF-1 levels during the whole prepubertal and pubertal period were significantly reduced in the parasitized when compared with antiparasitic-treated age-matched animals (Lacau-Mengido et al, 2000). The IGF-1 is a key factor for mammary gland development during the peripubertal period, and, consequently, a detrimental effect of parasites on parenchymal development was recently demonstrated (Perri et al, 2013). In the present work, to define the mechanisms involved in differential gland development, we investigated whether anthelmintic treatment in naturally infected dairy heifers during early development could modify the cellular division rate of mammary parenchymal and stromal cells as well as the expression pattern of modulators in the gland, such as IGF-1 system components and estradiol receptor α (ESR1).…”

The Notch system during pubertal development of the bovine mammary gland

“…Enhanced NICD proportion at 30 and/or 40 weeks of age evidenced for these three paralogues, coincides with high cell division rate demonstrated at these ages by PCNA immunostaining 39 . At this time, around the onset of puberty, mammary gland parenchyma undergoes active growth in response to high estrogen concentration 3,40 , coinciding with increasing estradiol receptor alpha expression in the mammary gland 39,41 , and increasing circulating estradiol and IGF1 levels 42,43 . To this respect, Notch signaling pattern has been related to estradiol receptor regulation in breast cancer 44,45 and in developmental studies in mouse 46 .…”

“…Udders were cleaned with soap and water, then rinsed and disinfected with iodinated solution. The biopsy was taken 2 cm away from the nipple, under local anesthesia (5 mL of lidocaine 2% sc) 40 . Each biopsy (at 20, 30, 40, and 70 wk) was obtained in a different place avoiding previous cicatrix.…”