ADSA Foundation Scholar Award: New frontiers in calf and heifer nutrition-From conception to puberty

摘要

Dairy calf nutrition is traditionally one of the mostoverlooked aspects of dairy management, despite itslarge effect on the efficiency and profitability of dairyoperations. Unfortunately, among all animals on thedairy farm, calves suffer from the highest rates ofmorbidity and mortality. These challenges have catalyzedcalf nutrition research over the past decade tomitigate high incidences of disease and death, andimprove animal health, growth, welfare, and industrysustainability. However, major knowledge gaps remainin several crucial stages of development. The purposeof this review is to summarize the key concepts of nutritionalphysiology and programming from conceptionto puberty and their subsequent effects on developmentof the calf, and ultimately, future performance. Duringfetal development, developmental plasticity is highest.At this time, maternal energy and protein consumptioncan influence fetal development, likely playing a criticalrole in calf and heifer development and, importantly,future production. After birth, the calf’s first meal ofcolostrum is crucial for the transfer of immunoglobulinto support calf health and survival. However, colostrumalso contains numerous bioactive proteins, lipids, andcarbohydrates that may play key roles in calf growthand health. Extending the delivery of these bioactivecompounds to the calf through a gradual transitionfrom colostrum to milk (i.e., extended colostrum ortransition milk feeding) may confer benefits in thefirst days and weeks of life to prepare the calf for thepreweaning period. Similarly, optimal nutrition duringthe preweaning period is vital. Preweaning calves arehighly susceptible to health challenges, and improvedcalf growth and health can positively influence futuremilk production. Throughout the world, the majorityof dairy calves rely on milk replacer to supply adequatenutrition. Recent research has started to re-evaluatetraditional formulations of milk replacers, which candiffer significantly in composition compared with wholemilk. Transitioning from a milk-based diet to solid feedis critical in the development of mature ruminants.Delaying weaning age and providing long and gradualstep-down protocols have become common to avoidproduction and health challenges. Yet, determininghow to appropriately balance the amount of energy andprotein supplied in both liquid and solid feeds based onpreweaning milk allowances, and further acknowledgingtheir interactions, shows great promise in improvinggrowth and health during weaning. After weaning andduring the onset of puberty, heifers are traditionally offeredhigh-forage diets. However, recent work suggeststhat an early switch to a high-forage diet will depressintake and development during the time when solidfeed efficiency is greatest. It has become increasinglyclear that there are great opportunities to advance ourknowledge of calf nutrition; yet, a more concentratedand rigorous approach to research that encompassesthe long-term consequences of nutritional regimens ateach stage of life is required to ensure the sustainabilityand efficiency of the global dairy industry.