Growth of digestive organs and their contents in holstein steers: relation to body weight and diet

Summary

This study describes the ontogeny of the bovine digestive tract in Holstein steers using allometric analysis across a wide range of bodyweights. Organ growth rates exceeded whole-body growth during the milk-to-solid-diet transition, then fell below whole-body growth rates post-transition, with the reticulo-rumen showing the highest post-transition growth rate. Diet type influenced digesta quantity and composition (hay-fed steers retained more digesta with lower dry matter content), with total tract digesta dry matter proportional to dry matter intake.

Regional applicability

Though the study was conducted in Canada, the findings are broadly applicable to UK intensive beef production systems using Holstein or similar dairy-breed steers. The relationships between diet type, digesta dynamics, and organ development are likely transferable to UK feeding systems, though regional variation in feed composition and management intensity should be considered when applying predictions.

Key measures

Empty organ weights (g), digesta weights (g), digesta dry matter (%), allometric growth coefficients (b values), dry matter intake, digesta composition by organ

Outcomes reported

The study measured growth of gastrointestinal tract organs (reticulo-rumen, omasum, abomasum, intestine) and their digesta content in Holstein steers slaughtered at six bodyweight intervals (60–500 kg) on concentrate or roughage diets. Allometric relationships between organ growth and total body growth were established, and digesta accumulation patterns were quantified by diet type.

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