Symposium review: Nutrition strategies for improved health, production, and fertility during the transition period

摘要

Dairy cow nutritional programs are a major determinantof the profitability of dairy farms. Despite this,the sustainability of the dairy enterprise is beyond justcow nutrition. For almost 50 yr, the NC-2042 project(Management Systems to Improve the Economic andEnvironmental Sustainability of Dairy Enterprises) hasbeen addressing most of these components as individualresearch units and in integrated ways. This review hasthe objective to report the body of research developedby members of the group in connection with the existingliterature on dietary formulation and feeding managementduring the dry period, peripartal period, andearly postpartum (fresh) period. Peak disease incidence(shortly after parturition) corresponds with the timeof greatest negative energy balance (NEB), the peakin blood concentrations of nonesterified fatty acids,and the greatest acceleration of milk yield. Decreasedfertility in the face of increasing milk production maybe attributable to greater severity of postpartal NEBresulting from inadequate transition management orincreased rates of disease. The depth and duration ofNEB is highly related to dry matter intake. Periparturientdiseases can result from adverse ruminal conditionscaused by excessive grain in the precalving or freshcow diet, perhaps aggravated by overcrowding, heatstress, or other stressors. Others have also implicatedinflammatory responses in alterations of metabolism,occurrence of health problems, and impaired reproduction.Providing controlled-energy and negative dietarycation-anion difference diets prepartum may improvedairy cow performance during the transition period.A major area of concern in the fresh cow period isa sudden increase in dietary energy density leadingto subacute ruminal acidosis, which can decrease drymatter intake and digestibility of nutrients. Adequatephysical form of the diet, derived from either forageneutral detergent fiber content or a mixing strategyof different ingredients in a total mixed ration, mustbe present to stimulate ruminal activity and chewingbehavior. In conclusion, formulation and delivery ofappropriate diets that limit total energy intake to requirementsbut also provide proper intakes of all othernutrients (including the most limiting amino acids Metand Lys) before calving can help lessen the extent ofNEB after calving. Effects of such diets on indicatorsof metabolic health are generally positive, suggestingthe potential to lessen effects of periparturient diseaseon fertility.