Hough, Robert L.2015-07-092015-07-091988http://hdl.handle.net/10919/54332Two studies were conducted to investigate factors involved in absorption of immunoglobulins in the preruminant neonate. In the first study 26 Angus cows were fed 57% or 100% of their NRC recommended requirements for protein and energy for the last third of gestation in each of 2 years. Resulting calves were fed measured amounts of colostrum from their dam or from a cow of the reciprocal nutritional treatment group. Cows from the restricted intake treatment lost weight and body condition (P < .05). Gestation length, birth weight, calving ease, days open end weaning weight, however, were not affected by treatment. Calves born to restricted fed dame had higher serum cortisol and lower serum T₃ concentration (P < .05), but absorption of IgG was not affected. Calves fed colostrum from restricted cows did have lower serum IgG concentrations (P < 0.2); although, none of the calves were considered hypogammaglobunemic. In the second study, 2 trials were conducted to evaluate the effect of varying cortisol concentrations on Ig absorption in lambs. Treatments consisted of control (CO), high cortisol (HC), single peak of cortisol (SP) end low cortisol (LC). Lambs in trial 1 were obtained on d 136 to 138 of gestation by caesarean operation. HC and SP lambs tended to have a faster rate of Ig absorption through 24 h, but did not differ from CO lambs in serum Ig concentration by 36 h. Precocious closure to Ig absorption had occurred for LC lambs by 20 h end they had lower Ig concentrations at 36 and 48 h (P < 0.05). In trial 2, lambs were obtained on d 140 to 142 of gestation. Lambs had a shorter Ig absorptive period than trial 1 (24 vs 36 h for CO]. Premature closure for the LC lambs occurred by 16 h postpartum (P < 0.05) and they tended to have depressed Ig concentrations post 24 h.x, 108 leavesapplication/pdfen-USIn CopyrightLD5655.V856 1988.H683ImmunoglobulinsVeterinary physiologyDissertation