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Purpose This study aimed to conduct a comprehensive review with meta-analysis to determine the effects of different forms of calf starters (ground, pelleted, textured, ground diets blended with hay, and textured diets blended with hay) on starter feed intake and growth rate of dairy calves during preweaning and postweaning periods. Sources The main sources for information and data included in this review were peer-reviewed literature from 1938 to 2021. The search engines Web of Science, PubMed, and Google Scholar were used. Findings of 37 full-text articles and 60 studies were Bayesian meta-analyzed for pooled estimates. Synthesis Newborn calves are not functional ruminants. Thus, this function must be developed, and that largely occurs due to the chemical composition of their diet and its fermentation in their rumens. There is ongoing discussion regarding what kinds of processing or form of calf starters should be used to improve growth performance of dairy calves. Conclusions and Applications This review article attempted to review all the literature related to different forms of starter feed (i.e., ground, pelleted, textured). It appears that considerable changes have occurred between 1938 and 2020 in the calf starter manufacturing process. Results of this meta-analysis showed that greater starter intake occurred when hay was supplemented to the finely ground starter (125 g/d) or when calves received textured starters compared with pelleted diets (107 g/d). Because variation is great in calf studies, there was not sufficient evidence for a recommended starter physical form for improving the growth rates of dairy calves. Processing of calf starter diets requires further investigation according to the guidelines for measuring and reporting calf and heifer experimental data. |
