Passive transfer of immunity and serum proteinogram during the first 35 days of age in Nelore calves conceived naturally or through in vitro fertilization / Transferência de imunidade passiva e proteinograma sérico até os 35 dias de vida em bezerros da raça Nelore concebidos naturalmente ou produtos da fecundação in vitro

ABSTRACT

Background: Some reports indicate that calves produced by in vitro fertilization (IVF) may have excessive birth weights, increasing the rates of dystocia. Prolonged labor can cause the birth of lethargic calves that slowly ingest colostrum; this may compromise the intestinal absorption of immunoglobulins. Although the number of beef calves produced by IVF is high in Brazil, there have been few physiological studies examining the neonatal period in such cases. The aim of this study was to evaluate the passive transfer of immunity, and characterize the variation in serum protein concentrations, in Nelore calves up to 35 days of age, comparing naturally conceived calves with those conceived by IVF. Materials, Methods & Results: Forty healthy newborn Nelore calves were randomly selected and allocated into two groups (n = 20) according to their method of conception (natural versus IVF), and each group was composed of ten males and ten females. All calves were born and raised on the same farm, and kept with their mothers on extensive management condition. Blood samples were collected between 24 and 36 h after birth, and at 7, 14, 21, 28, and 35 days of age. Total protein (TP) concentration in serum was measured by the biuret method, and gamma-glutamyl transferase (GGT) serum activity was measured by the kinetic method. Concentrations of serum albumin, as well as alpha 1-, alpha 2 [...]