The transition period—the 3 weeks before and 3 weeks after calving—is the most critical phase of the dairy cow's productive cycle for both welfare and production. More health problems, more welfare compromises, and more production losses originate from transition period management failures than any other management period.
At calving, the cow must simultaneously manage multiple physiological demands: preparation for lactation (enormous metabolic shift), immunological adaptation (colostrum production), recovery from calving, and resumption of reproductive cycling. These overlapping demands create a window of vulnerability where suboptimal management rapidly cascades into multiple health problems. The immune system is suppressed peripartum (negative effects of hormonal changes), making cows particularly susceptible to infectious disease.
Fresh cows cannot consume enough dry matter to meet the energy demands of early lactation, entering negative energy balance (NEB). The severity and duration of NEB determines welfare outcomes. In NEB, cows mobilise body fat, generating non-esterified fatty acids (NEFAs) and ketones. Excessive NEFA and ketone concentrations cause subclinical ketosis (reducing feed intake and milk production) and clinical ketosis (causing neurological signs, anorexia, and welfare emergency). NEFA measurement at calving predicts health outcomes for the subsequent lactation.
The transition period is associated with high prevalence of multiple welfare-compromising conditions: Milk fever (hypocalcaemia)—affects muscle and nerve function, causing recumbency and cardiac disturbances; Retained fetal membranes—increases uterine infection risk and requires treatment; Metritis—uterine infection causing systemic illness; Mastitis—udder infection causing pain and systemic inflammation; Displaced abomasum—surgical emergency causing chronic production loss. The aggregation of these conditions in poorly managed herds represents significant welfare burden.
Dry cow nutrition profoundly affects transition success. Over-fat cows (BCS >3.75) are more susceptible to metabolic disease—avoiding over-conditioning during the dry period is critical. Dietary cation-anion balance (DCAB) management in the close-up period can prevent hypocalcaemia by stimulating calcium mobilisation pathways. Adequate vitamin D, selenium, and vitamin E support immune function. A controlled-energy diet in the close-up period (last 3 weeks of pregnancy) helps prepare the cow's metabolic systems for lactation.
Transition cow housing requires careful attention to space and comfort. Overcrowding at the feed barrier (should be <80% occupancy) causes competition that reduces dry matter intake and worsens NEB. Stocking density should be ≤80% of cubicle capacity in transition areas. Clean, comfortable cubicles reduce mastitis risk. Clean calving areas minimise environmental pathogen exposure. The transition barn should be the best-housed area of the dairy, not an afterthought.
Proactive transition monitoring includes: BCS at dry-off and calving, ketone monitoring in fresh cows (using cowside blood meters or milk tests), NEFA measurement around calving in at-risk herds, and close observation of fresh cow behaviour (reduced feed intake is an early warning sign). Protocols for early intervention in cows showing early signs of metabolic compromise improve welfare outcomes and reduce the proportion reaching severe clinical disease.