The objective of this study was to determine the effects of dietary energy and recombinant bovine somatotropin (bST) injection to identify genes that might control mammogenesis. Total RNA was extracted from the parenchymal tissue of 32 heifers randomly assigned to one of four treatments: two diets (a standard diet and a high energy, high protein diet), each with or without bST. To perform microarray experiments, RNA samples were pooled (2 animals/pool) before reverse transcription and labeling with Cy3 or Cy5. […]

Forty Holstein cows, with previous reproductive problems, empty, at second or more lactations, with an average milk production of 9,200 kg in the previous lactation and a dry period over than 50 days were distruibuted in two groups to evaluate two protocols of milking induction. It was given to group 1, on days one, eight and 21 recombinant bovine somatotropin-bSTr (500 mg); from day two to eight, estradiol cypionate (0.075 mg/kg BW) and medroxi progesterone acetate (0.25 mg/kg BW); from […]

With the objective of evaluating different levels of IGF-I on the hepatical and intestinal indicators of cellular activity in newborn calves, 42 pregnant Holstein cows were randomly assigned to two groups: a) control: injection of vitamin E or b) rbST: injection of growth hormone (rbST). Injections started 35 days pre-partum and were repeated every 14 days until parturition. Newborn calves were randomly assigned to a 2 x 3 factorial arrangement of treatments (two mother groups and three different ages). After […]

Forty-two Holstein cows, pregnants and multiparous, wereassigned randomly to two groups to determine the possible alterations of IGF-I concentration in colostro and mammary secretions by changes in pre-partum blood serum IGF-I concentration, and also to compare its temporal changes with the serum immunoglobulin G (IgG) in pre-partum period. The treated group (n=21) received 500 mg of recombinant bovine somatotropin (rbST), and the control group (n=21) vitamin E injections. The treatments had been initiated 35 days pre-partum and repeated each 14 […]

The objective of this experiment was to study the progesterone plasma concentrations in crossbred heifers, and the correlation with lipid metabolites concentrations. Twenty-six heifers were distributed into two treatments: T1 – treated with 500 mg sometribove zinc (recombinant bovine somatotropin) on day 3 of superovulated estrous cycle and T2 – control. The blood samples were collected during two estrous cycles: normal and superovulated one. The progesterone and metabolic lipids concentrations were determined by RIA and enzymatic method, respectively. The experimental […]

A study was conducted to evaluate the effects of bST in crossbred dairy cows (Bos indicus x Bos taurus) raised in a semi-arid zone, in the Northeast of Brazil. Fifteen cows (second and third lactation; 42-155 days in milk) received five applications of bST, at 14-day intervals. Other 15 cows were used as controls. The animals were fed with diet consisted in elephant grass and concentrate. During the first application of bST, the milk production of the treated cows (12.6 […]