No abstract

The main waste generated in the milking parlours is manure-bearing wastewater. Its amount governs the total volume of manure output from the farm and the costs of its storage, processing and disposal. The aim of the research was to create models to minimise the output of this wastewater at the conceptual designing stage of dairy farms. The relevant technological, technical and organizational factors were analysed. Based on regulatory data, the encoded regression equations were obtained by computation for the daily output of manure-bearing wastewater from the milking parlours with herringbone, parallel and carousel (rotary) milking installations depending on the technological group size, milking installation capacity, number of floor washings and the milking time of the herd. The number of floor washings was found to have the greatest effect on the specific output of manure-bearing wastewater. The encoded equations were also obtained for determining the maximum number of cows to be milked on one milking installation that also depended on the technological group size, the milking installation capacity, and the time of one milking of the herd. The obtained equations were used to find the optimal solutions at the conceptual designing stage, to choose the technological parameters of the cow barn and the milking parlour by the criterion of the minimum output of manure-bearing wastewater, and to reduce the anthropogenic load on the environment. For the herd of 600 heads with 5-hour milking twice a day, the minimum specific output of manure-bearing wastewater of 5.4l•head-1 •day-1 was estimated for the case of the herringbone milking installation. The technological group should be of 60 heads, and the installation should have 40 milking units.

Ammonia emission and moisture evaporation from manure affect the climate inside the cow barn. According to our previous study, the manure surface area is of greater importance than its layer thickness in this respect. However, in practice, the manure passage area cannot be reduced in the loose housing of cows in cubicles. Therefore, other factors contributing to emission abatement are to be considered. The study objective was to identify the relation between the ammonia emission and moisture evaporation from cattle manure and the manure moisture and excrement content. For this purpose, a laboratory-scale set-up was designed. It consisted of a case with a fan installed and an exhaust pipe with a gas detector and an air velocity transmitter. The initial relative moisture content of cow excrement was 89 %. Peat with 57 % moisture content was added to reduce it, and tap water was added to increase it. The mass of each sample was 1 kg. In the experiment, the tested sample was placed in the set-up; the air was blown over its surface by the fan and the sensors in the pipe recorded the ammonia concentration and the airflow rate. Each experiment lasted for 30 minutes. The ammonia emission was calculated by the common methodology. The moisture evaporation was determined by the change in the sample mass during the experiment. The study results showed that the average ammonia emission from the initial excrement with 89 % moisture content was 68.26 mg•h -1 . When peat was added and the mixture moisture content reduced to 84 %, the average ammonia emission was 41.57 mg•h -1 . When water was added and the mixture moisture content increased to 94 %, the average ammonia emission was 32.93 mg•h -1 . In terms of the excrement unit, the ammonia emission decreased by 30.1 % when peat was added and only by 9 % when water was added. Therefore, the animal housing on bedding is preferable to reduce the ammonia emission from manure and to create a more favorable climate in the cow barn.

Under a loose cow housing practice with automated milking installations, the manure removal system receives both manure from the barns and manure-bearing wastewater from the milking parlour. This is a mixture of animal excrement and washing water of frames and partitions in the milking installation and the manure-soiled floors and walls. The purpose of the study was to monitor the amount of washing water actually consumed in the milking parlour and subsequently entering the manure removal system. The monitoring was conducted on a farm in the Leningrad Region with an average dairy herd of 596 cows and three milkings a day in a Parallel 2x20 parlour. Electronic flowmeters were installed in the connection points of the washing equipment to the water supply system. They automatically recorded the water consumption every hour in the internal memory. The area, including the cow passages, was 255 m2 (milking parlour) and 267 m2 (holding area and sanitary zone). The holding area and the milking parlour were washed after each milking using high-pressure equipment. During the monitoring, the daily water consumption in the milking parlour varied from 11.3 to 17.5 m3. The average daily water consumption was 14.4 m3. The main amount of water was used in the milker's pit and averaged 64.6% of the total; 10.6% of the total water was used for washing the floor and walls with high-pressure equipment. The maximum water consumption was observed at the end of each milking, when the holding and milking areas were cleaned. The average amount of consumed water was 24 l cow-1•day-1, i.e. 8 l•cow-1 per milking. The study results are needed for correct dimensioning of manure storage facilities. They can be also used to calculate the moisture content of manure produced and, in case of its further separation, to determine the amount and moisture content of resulting fractions.