One of the factors contributing to higher milk productivity and good health of cows is sufficient and reliable round-the-clock water supply. Scarce water consumption leads to irreversible processes in the animal body, up to its death. The aim of this study was to measure the drinking water consumption in the loose housing system of cows with consideration of the time of day, the milk yield and the indoor barn climate. The study was conducted in August-November 2019 in a cow barn with the loose housing system. The inside climate was maintained by a natural ventilation system through the light ridge on the roof and by adjustable systemsinflatable membranes on the windows and air blowers installed inside the barn. The group of animals consisted of 80 Holstein cows with the productivity of 10 000 to 12 000 kg of milk per head per lactation period. During the study, the average drinking water consumption was 1.99 ± 0.26 l•l -1 of milk. Near the waterers, the air temperature ranged from + 2.7 ºС to + 20.8 ºС, with the relative humidity being 78.4-100 %. The maximum average water consumption of 6.5 l•head -1 •hour -1 was registered after the evening milking, the minimum of 0.8 l•head -1 •hour -1 was observed during the morning feeding. The water consumption increased in the first hour after the afternoon and evening milkings by 40-45 % that was associated with the water balance restoration in the animals' body. The study revealed the dependences of the drinking water consumption on the milk yield and the temperature and humidity conditions in the barn; graphical and mathematical models were constructed. This study is required to create a comprehensive model for the optimal drinking water supply of cows on dairy farms under reasonable energy and water inputs.

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.

При выборе типа доильной установки и ее размера необходимо учитывать максимальное планируемое поголовье дойных коров и размер технологической группы, кратность и время одного доения, продолжительность рабочей смены дояров. Анализ технико-экономических показателей наиболее распространенных на сегодняшний день типов доильных установок одинакового технического уровня свидетельствует, что наилучшие удельные показатели имеет установка типа «Карусель» (1), а установка типа «Елочка» (2) требует более высоких затрат труда и средств. Установка «Параллель» (3) занимает промежуточное положение. Из анализа пропускной способности и количества необходимых операторов: установка 2 рекомендована для ферм с поголовьем дойного стада до 600 голов, 3 — не более 1200 дойных коров, 1 — более 1200 дойных коров. «Карусель» — наиболее рациональный, высокопроизводительный, легко автоматизируемый и, следовательно, перспективный способ доения в залах, особенно для крупных молочных ферм. The choice of the proper type and size of milking installations needs to take into account the maximum planned number of dairy cows, the size of a technological group, the number of milkings per day, and the duration of one milking and the operator's working shift. The analysis of technical and economic indicators of currently most common types of milking machines of the same technical level revealed that the Carousel installation had the best specific indicators while the Herringbone installation featured higher labour inputs and cash costs. The Parallel installation was found somewhere in between. In terms of the throughput and the required number of operators Herringbone is recommended for farms with up to 600 dairy cows, Parallel — below 1200 dairy cows, Carousel — above 1200 dairy cows. Carousel was found the most practical, high-performance, easily automated and, therefore, promising milking system for milking parlours, especially on the large-scale dairy farms.

Water temperature in the drinkers and humid environment combined with low or high air barn temperature are equally important factors for cow health, water intake and milk productivity. The study purpose was to determine the water intake by lactating cows from heated drinkers with different location and water temperature and the barn climate in North-West Russia. A group of Holstein dairy cows with loose housing in boxes was selected for the study. Two automatic group drinkers with heating elements were installed in different places in the barn. The experiments had two variants of the drinkers' operation mode. In Variant 1, the heating element in Drinker 1 was switched off, in Drinker 2switched on. In Variant 2, the heating elements were switched off in both drinkers. In Variant 1, the difference in the average daily water temperature between Drinker 1 and Drinker 2 was from 4.8 °С to 6.2 °С, with the average daily air temperature in the barn being from +11.7 °С to +14.8 °С. In this case, the water intake from Drinker 2 with higher, the water temperature was 2.5-5 times bigger than that from Drinker 1. In Variant 2, the difference in water intake between Drinker 1 and Drinker 2 was 35.1-72.3%. At that time, the average daily air temperature in the barn ranged between +10.7 °С and +14.9 °С. The average daily water temperature in the drinkers was from +6.3 С to +8.7 С, with the difference between the drinkers not exceeding 0.8 С. During the study, the milk yield was from 36.3 to 41.4 kg•cow -1•day -1, with the water intake being from 1.96 l•kg -1 to 2.48 l•kg -1 . During the experiments, the cow diets did not change. The graphical models based on the experimental data allowed estimating the effect of water temperature on water intake by cows. The study also showed that drinkers' location influenced the water intake. So, when designing the modern drinking systems, more attention is needed to their optimal placement and provision of free access to freshwater for animals at all times.