The objectives were to investigate the effects that maternal diets containing negative dietary cation-anion differences (DCAD) fed in the last 42 d of gestation may have on the acid-base status, hematology, mineral and energy metabolism, growth, and health of calves. The experiment was a randomized block design with a 2 × 2 factorial arrangement of 2 levels of negative DCAD (-70 or -180 mEq/kg) and 2 feeding durations (the last 21 d prepartum and the last 42 d prepartum). Bulls and heifers (n = 60) born to these dams were weighted at birth and fed 3.8 L of colostrum for their first feeding, and only heifers (n = 44, 9-12/treatment) were kept thereafter. Heifer body weight was also recorded at 21 d, 42 d, 62 d, 3 mo, and 6 mo of age. Blood was collected at birth, before colostrum feeding, and at 1, 2, 3, 21, and 42 d of age and assayed for minerals, metabolites, and cell counts. Heifers born to dams fed the last 42 d prepartum weighed 2.8 and 4.8 kg less at birth and 62 d, respectively, compared with calves born to dams fed the last 21 d prepartum; however, body weight at 3 and 6 mo of age was similar. Concentrations of ionized calcium did not differ among treatments at birth, but heifers born to -180 DCAD dams had increased blood concentrations at 3 d of age, whereas those born to -70 DCAD dams did not. At birth, heifers born to -180 DCAD dams experienced a subtle and transient metabolic acidosis (pH = 7.33 ± 0.02; pCO = 53.0 ± 2.4 mmHg; HCO = 27.6 ± 0.7 mmol/L) compared with the more evident metabolic acidosis observed in those born to -70 DCAD cows (pH = 7.28 ± 0.02; pCO = 59.3 ± 2.4 mmHg; HCO = 27.8 ± 0.7 mmol/L). Heifers born to -180 DCAD dams had reduced concentrations of β-hydroxybutric acid and nonesterified fatty acids compared with those born to -70 DCAD dams. Efficiency of IgG transfer from colostrum into blood and serum concentrations did not differ among treatments. There was no relationship between measures of metabolic acidosis and measures of efficiency of IgG absorption. Percentage of lymphocytes and neutrophils was altered by maternal treatments; however, treatments did not affect calf morbidity. Extending the duration of feeding up to 42 d or reducing the level of negative DCAD to -180 mEq/kg in maternal diets exerted a transient metabolic acidosis in the calves and slightly affected measures of mineral, energy metabolism, and growth.

Se ha determinado la influencia que la administración endovenosa de renina tiene sobre el flujo coronario fásico. La renina ocasionó un aumento del flujo coronario fásico. En dos expericencias hubo una disminución inicial moderada, y sumamente breve (un minuto) del flujo coronario. El aumento del flujo sanguíneo coronario alcanzó su mayor valor 3 a 5 minutos después de la administración de la sustancia. El flujo sanguíneo coronario se mantuvo aumentado mientras duró la acción hipertensiva de la renina. El flujo sanguíneo coronario siguió a la presión arterial y alcanzó su mayor valor junto con ella. Se planteó la posibilidad de una dilatación coronaria originada por la renina.