Effect of Forage‐Free Diet on the Growth Performance, Feed Efficiency, Blood Metabolites, and Mammary Gland Parenchyma of Prepubertal Holstein Heifers

Variation in nutritional profile and availability of high-quality forages remain primary challenges for efficient heifer rearing on a forage-based diet. This study aimed to evaluate the effect of limit feeding forage-free diet on growth performance, feed efficiency, blood metabolites, behavior, health, and mammary parenchyma of prepubertal dairy heifers. Sixteen prepubertal heifers (Body weight = 168 ± 32Kg) divided into 8 pens (2 heifers/pen) were used in a completely randomized design (n = 4 pen/treatment) to compare the effect of a diet containing 20% forage with a forage-free diet. Limit feeding forage-free diet improved the feed efficiency by 10% and ADG by 11.36% (p ≤ 0.05) without negatively affecting the body measurements, health parameters, and blood metabolites (p ≥ 0.23). In udder, three-quarters of heifers fed a forage-free diet had greater (p ≤ 0.05) mammary parenchyma growth than the heifers fed a 20% forage diet. Teat lengths and behavioral measurements except rumination time were not affected (p > 0.05) by the forage-free diet. Heifers fed a 20% forage diet had greater rumination time (p = 0.01) than the heifers fed a forage-free diet. Limit feeding forage-free diet can be adopted in prepubertal dairy heifers for the improvement in feed efficiency and mammary parenchyma growth.