Effect of dietary supplementation of 2 forms of a B vitamin and choline blend on the performance of Holstein calves during the transition and postweaning phase.

The transition from a liquid- to a solid-based diet involves several adaptations in calves. Development of ruminal function is likely to alter B vitamin and choline supply, although little is known about the extent of these changes relative to the calf's requirements and consequences for the calf around weaning. Moreover, literature data are equivocal concerning the need to supplement B vitamins and choline through weaning and transition phase of the dairy calf.

Effects of rumen-protected methionine or methionine analogs in starter on plasma metabolites, growth, and efficiency of Holstein calves from 14 to 91 d of age.

During weaning, methionine (Met) supply decreases as liquid feed intake is reduced and ruminal function is developing. During this transition, the calf starter should both promote ruminal development and provide adequate nutrients post-ruminally. In mature ruminants, rumen-protected Met (RPM) and the Met analogs, 2-hydroxy-4-(methylthio)-butanoic acid (HMTBa) and HMTBa isopropyl ester (HMBi), are used to increase Met supply, stimulate ruminal fermentation, or exert both effects, respectively.