Preweaning to postweaning rumen papillae structural growth, ruminal fermentation characteristics, and acute-phase proteins in calves

This study evaluated pre- to postweaning ruminal structural development, fermentation characteristics, and acute-phase protein levels in calves with a high milk replacer (MR) feeding rate prior weaning. Six ruminally cannulated Holstein bull were fed MR (150 g/L) at 15% of body weight (BW) 2 equal volumes daily. Volumes adjusted weekly based on BW. Calves weaned using 1-step weaning method, decreased by 50% the end wk 5 full 6. Calf starter, chopped straw, water offered ad libitum. Intake was recorded daily, BW weekly. From 12, pH continuously measured bolus. Ruminal fluid collected from 12 for measurement short-chain fatty acid concentrations quantification total bacteria protozoa. Rumen papillae obtained 5, 6, 7, 8, histological analysis. Serum amyloid A lipopolysaccharide-binding Data analyzed GLIMMIX procedure SAS (SAS Institute Inc., Cary, NC), week as fixed effect calf random effect. During step-down, starter intake 3-fold higher continued increase until 12. Body increased birth 12; however, did not change during possibly due low metabolizable energy caused strategy. Preweaning below 5.8 approximately 936.3 ± 125.99 min/d, implying acidosis. Furthermore, reached peak 8 1,203.9 227.65 min/d slowly 388.1 189.82 Papillae surface area, length, width compared 5. Corneum thickness week, whereas spinosum/basale only The concentration highest 1 then remained constant In conclusion, even before step-down weaning, experienced acidosis despite intake. Further, observed prolonged depression suggests that dietary rumen adaptation after can take several weeks preweaning. depressed affect proteins this finding, along other results, epithelium barrier integrity is compromised