Differential adaptation of performance, metabolism and endocrine systems to lactational and nutrition induced negative energy balance of dairy cows

Performance, metabolic and endocrine parameters were determined to study the effects of a negative energy balance (NEB) on adaptability in dairy cows. Besides the NEB induced by lactation immediately post partum, responses during a deliberately induced NEB by feed-restriction at around 100 days in milk were investigated. The extent of changes in the studied parameters was smaller during the deliberately induced NEB compared to the NEB in early lactation, even though the induced NEB by feed-restriction was greater. The different adaptive reactions of dairy cows to an energy deficiency at two stages in lactation indicate the different levels of metabolic priority during the course of lactation.