The impact of automated, constant incomplete milking on energy balance, udder health, and subsequent performance in early lactation of dairy cows

Abstract

During the first weeks of lactation, dairy cows experience a negative energy balance (NEB), because the energy supply provided by feed intake can not cover the energy needed for maintenance and rising milk production at that time. The non-esterified fatty acids (NEFA) released from the adipose depots represent a major energy source for the cow in early lactation. However, the capacity of the liver for full NEFA oxidation is limited, resulting in either an excess storage as triglycerides in the liver or incomplete oxidation, which further promotes ketogenesis. Metabolic disorders are known to be an important risk factor for other diseases in early lactation and cause high costs due to the loss of performance and veterinary treatment. Incomplete milking (IM) represents one of the options to delay the increase in milk yield and to modify the energy output with milk as one of the main variables affecting the energy balance (EB). Our objectives were to test the effects of IM in early lactation on EB, metabolic status, udder health, and subsequent performance. An automated software module was used, which enables an automatic cluster removal when a defined milk quantity (kg) instead of a defined milk flow (kg/min) is reached. Forty-six Holstein cows were equally allocated to either the treatment (TRT, n = 23; starting on days in milk (DIM) 8 ± 1.1) or the control group (CON, n = 23; conventional cluster removal at a milk flow rate < 0.3 kg/min). The amount of milk in the TRT group was clamped during IM to the milk yield of each cow 1 day before IM was started and held constant for 14 days. Thereafter, all cows were conventionally milked and records related to EB, performance, and udder health were continued up to 15 week of lactation. During the 2-week IM, on average 11.1% less milk were obtained from the TRT group than from the CON group. After IM, milk yield increased in the TRT group eliminating the group difference throughout the remaining observation period until week 15 of lactation. Udder health was not compromised during the entire observation period in all cows. The TRT cows tended to have less feed intake and also water intake than the CON cows during the 2-wk of IM. The extent of the NEB and the circulating concentrations of NEFA, β-hydroxybutyrate, insulin-like growth factor-1 (IGF-1), and leptin did mostly not differ between the groups. The IM did not affect body condition. Our findings confirm the practicability of the milking software module for an automated, constant milk withdrawal to delay the increase in milk yield during the first weeks of lactation without affecting udder health and subsequent performance. However, it remains to be determined whether the absent effect on energy metabolism was due to the relatively stable energy status of the cows or to the relatively mild IM setting used herein. Further research is needed to understand the link between the degree and duration of IM and the adaptive mechanism of the organism in terms of milk synthesis, feed intake, and energy metabolism.