Growth performance and metabolic and endocrine traits in calves pair-fed by bucket or by automate starting in the neonatal period.

Effects of different feeding frequencies on growth performance, preprandial metabolic parameters, and endocrine traits were studied in calves up to 28 d after birth and respective postprandial changes were investigated on d 3 and 7. Calves were fed with a computer-programmed automate that allowed frequent daily intakes (GrA; n = 7) or were fed twice daily by bucket (GrB; n = 7) the same daily amounts (pair-feeding) of colostrum and milk. Weight gains did not differ significantly between groups. Plasma protein was higher (P < 0.01) from d 14 to 28 in GrB than in GrA. Plasma glucose increased postprandially in GrB on d 3 and 7 but in GrA only on d 3, and there was a significant treatment x time interaction on d 3 and 7 after feed intake. For plasma triglycerides there was a significant postprandial treatment x time interaction on d 3, and triglycerides were higher (P < 0.05) in GrA than in GrB before feed intake on d 7. For insulin concentrations on d 7 the treatment x time interaction was significant and concentrations 8 h after feed intake were higher (P < 0.05) in GrA than GrB. For concentrations of growth hormone on d 7 during an 8-h period the treatment x time interaction was significant and concentrations from 320 to 340 min after feed intake were higher (P < 0.05) in GrB than in GrA. Plasma IGF-I concentrations were higher (P < 0.05) in GrA than in GrB on d 7. The hematocrit and concentrations of immunoglobulin G, albumin, urea, creatinine, L-lactate, nonesterified fatty acids, cholesterol, glucagon, and thyroxine did not differ between groups. In conclusion, feed intake at high frequency by an automate transiently changed some metabolic and endocrine traits (glucose, triglyceride, insulin, and IGF-I) but had no significant effects on growth performance during the first 4 wk of life.