44- Mammary biopsies in Prepubertal Heifers. Histological studies of the developmental gland. Effect of anthelmintic treatment.

LICOFF, N; DIAB, S; PERRI, AF; MEJIA, ME; FORMIA, N; BECU-VILLALOBOS, D; LACAU-MENGIDO, I

Tandil, Pcia de BsAs

Congreso; XL Congreso de la Sociedad Argentina de Farmacología Experimental; 2008

SAFE

In previous studies we demonstrated that IGF-1 levels were diminished in parasitized heifers calves compared to ivermectin treated ones during development. As IGF-1 is involved in prepubertal mammary growth the present study was conducted in order to determine if parasite infection could also affect mammary gland development. Twenty new born female Holstein calves were randomly assigned to treated or untreated group. The treated group was maintained with minimal parasite burden by means of strategic treatments with ivermectin, fenbendazole or levamisole. Every month animals were weighed, feces were collected for EPG counting and blood was collected for IGF-1 determinations. Six heifers (3 per group) were used to set up a mammary biopsy technique and then to compare development of the mammary parenchyma by histology. Four biopsy samples were taken from each heifer at 20, 30, 40 and 60 week of age. Heifers were immobilized lying on the floor; the udder was washed thoroughly, then disinfected and locally anesthetized. Biopsies were taken using a Tru-Core® Biopsy Needle (Medical Device Technologies, Inc.) and then kept in formalin solution (10%) at 4°C for histology. Systemic antibiotic was dosed after sampling. Only when the 60 weeks samples were taken, heifers were sedated with acepromazine. Heifers in the treated group grew faster than those in the untreated one and IGF-1 levels were increased, as expected. The mammary biopsy technique was reliable and efficient. Samples quantity and quality was satisfactory. Biopsy sites healed rapidly and without infections. Histological examination of the biopsies showed mammary parenchyma embedded in fat pad, conforming ductal developing structures of epithelial cells. As the animal grew up more organized ductal structures were observed. When different areas were measured, a different ratio of epithelial cells/total area was evidenced between groups at 20 weeks of age. Heifers in the treated group had higher percentage of ductal epithelial cells than did untreated ones. At higher ages the difference was not evident. We conclude that Ivermectin treatment during development could increase early ductal mammogenesis in association with increased IGF-1 levels. Molecular studies will be performed in further studies.