Insulin-like growth factor-i during the formation and transfer of passive immunity to newborn calves. / Fator de crescimento semelhante à insulina-I no período de formação e transferência de imunidade passiva para bezerros recém-nascidos.

AUTOR(ES)

Patricia Pauletti

DATA DE PUBLICAÇÃO

2004

RESUMO

Forty-two Holstein cows, in gestation and multiparous, and their newborn calves were used to evaluate if insulin-like growth factor-I (IGF-I) in colostrum and subsequent mammary secretions could be influenced by changes in blood serum IGF-I and compare its temporal changes with the serum immunoglobulin G (IgG) in pre-partum period, as well as the temporal changes in serum IGF-I and IgG in newborn calves during the first week of life, and also, alterations in its intestinal mucosa. Cows were randomly assigned in two groups of twenty-one animals, treated group was injected 500 mg of recombinant bovine somatotropin (rbST), and the control group received vitamin E injection. Both treatments started 35 days pre-partum and were administered every 14 days until partum. Weekly body condition scores were measured and blood was collected until partum. Colostrum and mammary secretions were collected daily for seven days pos-partum. Newborn calves were randomly assigned to a 2X3 factorial arrangement, which the factors depended on mother’s treatment (control and rbST) and slaughter date (just after birth, two days of life and seven days of life). Blood was collected daily until slaughter. For stereological analysis samples were taken from five sites from small intestine. Body condition scores and nonesterified fatty acid concentration didn t differ between the groups during the experimental period (P>0,05). Groups differed about serum IGF-I during pre-partum (P<0,05), which showed differences on second and fourth weeks of experimental period in response to rbST administration. However, no treatment differences were found at partum (P>0,05). IGF-I concentration was higher in colostrum of cows treated with rbST (P<0,05), but it didn t differ in subsequent mammary secretions. IgG serum concentration didn t differ between treatments during the experimental period, neither IgG concentration in colostrum and subsequent mammary secretions (P>0,05). No differences were found either in calves’ IGF-I levels from birth to seven days old or in IgG serum concentration after 24 hours of life (P>0,05). Organ weight and mucosa partial volume (Vv) didn t differ between treatments in the three slaughter dates, only differences among the salughter dates were observed. Segment from the medium jejunum showed higher Vv in relation to others segments at birth and seven days old. The administration of rbST during the dry period influenced only IGF-I concentration in colostrum, however colostrum IGF-I didn’t affect calves’ serum concentration up to seven days old, neither the mucosa Vv of small intestine.

ASSUNTO(S)

fator crescimento growth factors antibodies anticorpos vacas bezerro intestino delgado cows calves small intestine

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