Effect of low frequency oscillations during milking on udder temperature and welfare of dairy cows

Abstract

The study aimed to investigate the effect of low-frequency oscillations on the cow udder, milk parameters, and animal welfare during the automated milking process. The study's objective was to investigate the impact of low-frequency oscillations on the udder and teats' blood circulation by creating a mathematical model of mammary glands, using milkers and vibrators to analyze the theoretical dynamics of oscillations. The mechanical vibration device developed and tested in the study was mounted on a DeLaval automatic milking machine, which excited the udder with low-frequency oscillations, allowing the analysis of input parameters (temperature, oscillation amplitude) and using feedback data, changing the device parameters such as vibration frequency and duration. The experimental study was performed using an artificial cow's udder model with and without milk and a DeLaval milking machine, exciting the model with low-frequency harmonic oscillations (frequency range 15-60 Hz, vibration amplitude 2-5 mm). The investigation in vitro applying low-frequency of the vibration system's first-order frequencies in lateral (X) direction showed the low-frequency values of 23.5-26.5 Hz (effective frequency of the simulation analysis was 25.0 Hz). The tested values of the first-order frequency of the vibration system in the vertical (Y) direction were 37.5-41.5 Hz (effective frequency of the simulation analysis was 41.0 Hz), with higher amplitude and lower vibration damping. During in vivo experiments, while milking, the vibrator was inducing mechanical milking-similar vibrations in the udder. The vibrations were spreading to the entire udder and caused physiotherapeutic effects such as activated physiological processes and increased udder base temperature by 0.57°C (p < 0.001), thus increasing blood flow in the udder. Used low-frequency vibrations did not significantly affect milk yield, milk composition, milk quality indicators, and animal welfare. The investigation results showed that applying low-frequency vibration on a cow udder during automatic milking is a non-invasive, efficient method to stimulate blood circulation in the udder and improve teat and udder health without changing milk quality and production. Further studies will be carried out in the following research phase on clinical and subclinical mastitis cows.

Keywords: Animal welfare; Low-frequency vibrations; Milk parameters.

Fig. 1.. Diagram of a milking unit with an unbalanced vibratory motor for excitation of the udder.

(A) 1, udder; 2, teat; 3, mouthpiece; 4, unbalanced motor; 5, vibrators; 6, shell; 7, short milk tube; 8, stand. (B) Its simplified 2D dynamic model with vibratory motion in the X-Y plane. (C) Milking unit (claw) and pipeline milking system; 9, long pulse tube; 10, milking unit; 11, long milk tube (milk hose); 12, claw; 13, short milk tube; 14, short pulse tube; 15, teat cup shell [17].

Fig. 2.. Setup of the testing rig for the application of low-frequency harmonic oscillation device on the artificial cow udder model.

(A) Experimental setup, (B) basic view of the model (stand): 1, X-axis accelerometer KD35 (RFT GmbH, Schwabmünchen, Germany); 2, computer; 3, power supply HY1803D (V&A Instruments, Shanghai, China); 4, oscilloscope PicoScope 3424 (Pico Technology, Cambridgeshire, UK); 5, teat of the model; 6, unbalanced vibratory motor; 7, Y-axis accelerometer KD35 (RFT GmbH); 8, milker device (Harmony model); 9, artificial cow udder model.

Fig. 3.. Setup of the testing rig for the application low-frequency harmonic oscillation device on a live animal (cow).

(A) Structural scheme, (B) milker with a special created vibrator and two accelerometers, (C) experiment during milking process. 1, cow udder; 2, milker with the vibrators and accelerometers; 3, holder; 4, unbalanced vibratory motor; 5, oscilloscope PicoScope 3424 (Pico Technology); 6, computer; 7, power supply HY1803D (V&A Instruments); 8, X-axis accelerometer computer; 9, Y-axis accelerometer.

Fig. 4.. Frequency-amplitude characteristics.

(A) in X-axis when the model (stand) was without milk, (B) in Y-axis when the model (stand) was without milk, (C) in X-axis when the model (stand) was filled with milk, (D) in Y-axis when the model (stand) was filled with milk. LF, left front; LB, left bottom; RF, right front; RB, right bottom.

Fig. 5.. Frequency amplitude characteristics.

(A) in X-axis, on a live animal (cow), (B) in Y-axis, on a live animal (cow). Only one teat was affected during one session of vibration; the teats are indicated as follows: LF, left front; LB, left bottom; RF, right front; RB, right bottom.

Fig. 6.. Frequency-amplitude characteristics using theoretical calculations on the X and Y axes.

Fig. 7.. Changes in superficial mammary gland temperature during milking.