RESUMEN

Robotic milking systems are successful innovations in the development of dairy cattle. The objective of this study was to analyse the milking characteristics and behavior of dairy cows of different calving orders in "milk first" robotic milking systems. The data were collected from a commercial herd located in the Midwest region of Minas Gerais (Brazil), which uses an automatic milking system (AMS TM, DeLaval). Were analysed 26,574 observations of 235 Holstein cows were available. Data were evaluated by multivariate analysis of variance and the Tukey test. - Tthe characteristics milk flow and milking efficiency were more favourable for multiparous cows (p <0.01), while the time in the stall was more favourable for primiparous females (p <0.01). The values of handling time were better in the primiparous cows (p <0.01). Primiparous cows had higher amounts of kick-off (p <0.001), and multiparous cows had higher incomplete milkings (p <0.001). The number of incomplete milkings showed a higher ratio in terms of reduction in milk production in 26.6% in primiparous cows and 26.7% in multiparous cows (p <0.01). Regarding the behavioral characteristics, primiparous cows had higher amounts of kickbacks, while multiparous cows had greater quantities of incomplete milkings.

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The main challenge in milk production has been to maintain a focus on efficient processes that enhance production outcomes while aligning with animal welfare and sustainability and being valued by society. As an alternative to improve cow welfare in production and provide better handling of the waste generated by the activity, the system called the compost-bedded pack barn (CBP) has been widely adopted in countries with temperate climates and higher milk production. This CBP has been attracting global interest, including from countries with tropical and subtropical climates, such as Brazil, where many producers have started to use it due to the response in terms of milk productivity. A CBP can be designed either in (a) an open facility with natural ventilation or a positive-pressure ventilation system or (b) totally closed facilities, equipped with negative-pressure ventilation systems and permanent thermal control. The latter system is being implemented in Brazil, despite insufficient knowledge about its efficiency. The objective of this study was, through a review, to gather and describe the most recent information on the use of open and closed CBP systems for dairy cattle housing, mainly covering how it is applied in tropical climate regions. To achieve the proposed objective, this review study included the following topics related to CBPs: (i) implementation, (ii) bedding, (iii) general construction and architectural characteristics, and (iv) ambient thermal conditioning. Knowledge gaps and directions for future research are also identified here.

RESUMEN

The objective of this study was to characterize the dependence and spatial distribution of bedding attributes in an open compost-bedded pack barn (CBP) system with positive pressure ventilation during the winter period in Brazil. The study was conducted in July 2021, in the Zona da Mata region, Minas Gerais, Brazil. The bedding area (shavings and wood sawdust) was divided into a mesh with 44 equidistant points. At each point, the bedding temperature at the surface (tB-sur) and at a depth of 0.2 m (tB-20) and the air velocity at bedding level (vair,B) were measured, and bedding samples were collected. The bedding samples were used to determine the moisture level and pH at the surface (MB-sur e pHB-sur) and at a depth of 0.2 m (MB-20 and pHB-20). The spatial behavior of the variables was evaluated using geostatistics techniques. For all variables, the occurrence of strong spatial dependence was verified. Through the maps, it was observed that tB-sur, tB-20, MB-sur, MB-20, and vair,B showed high spatial variability, whereas pHB-sur and pHB-20 demonstrated low variation. On the surface, values of tB-sur < 20 °C and MB-sur > 60% were observed. At the subsurface, there was a predominance of tB-20 < 40 °C, MB-20 > 60%, and pH > 9, which are indications of low bedding composting activity.

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Air quality is one of the main factors that must be guaranteed in animal production. However, the measurement of pollutants is still a problem in several countries because the available methods are costly and do not always apply to the reality of the constructive typology adopted, as in countries with a hot climate, which adopt predominantly open facilities. Thus, the objective of the present study was to develop predictive models for the potential generation and emission of ammonia in the production of broiler chickens with different types of litter, different reuse cycles and under different climatic conditions. Samples of poultry litter from thirty commercial aviaries submitted to different air temperatures were analyzed. The experiment was conducted and analyzed in a completely randomized design, following a factorial scheme. Models were developed to predict the potential for generation and emission of ammonia, which can be applied in facilities with ambient conditions of air temperature between 25 and 40 °C and with wood shaving bed with up to four reuse cycles and coffee husks bed with up to six reuse cycles. The developed and validated models showed high accuracy indicating that they can be used to estimate the potential for ammonia generation and emission.

RESUMEN

External egg quality is an essential parameter of egg production as it relates directly to economic losses. This study evaluated the spatial variability of external egg quality in five naturally ventilated caged vertical aviaries. Differences caused by bird age and thermal and luminous variability within aviaries during winter and summer were analyzed. Data on aviary air temperature, relative humidity, light intensity, and external egg quality were collected at evenly distributed points along the aviary length within three levels of cages. The experimental design was completely randomized in a factorial scheme. In the summer, the highest air temperature and lowest relative humidity were found in central cages, mainly in upper center cages; hens produced eggs with a lower weight and shape index in this area. Similar results were obtained in the winter. In the summer, eggs with lower shell weight and thickness were also produced by hens housed in the central cages, but in the winter, the opposite result was obtained. This study of the spatial variability of external egg quality proved efficient in detecting areas within an aviary with poor quality eggs; improvements to design and management in these areas could help management improve production efficiency and contribute to a sustainable egg supply.

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Due to climate change, heat stress is a growing problem for the dairy industry. Based on this, annual economic losses in the dairy sector are verified mainly on a large scale. Despite several publications on thermal stress in lactating dairy cows in confinement systems, there need to be published reviews addressing this issue systematically. Our objective was to scientometrically analyze the effects of heat stress in dairy cows managed in a confinement system. Based on PRISMA guidelines, research articles were identified, screened, and summarized based on inclusion criteria for heat stress in a confinement system. Data was obtained from the Web of Science. A total of 604 scientific articles published between 2000 and April 2022 were considered. Data was then analyzed using Microsoft Excel and CiteSpace. The results pointed to a significant increase in studies on heat stress in lactating cows housed in confinement systems. The main research areas were Agriculture, Dairy Animal Science and Veterinary Sciences. The USA showed the highest concentration of studies (31.12%), followed by China (14.90%). Emerging themes included heat stress and behavior. The most influential journals were the Journal of Dairy Science and the Journal of Animal Science. The top authors were L. H. Baumgard and R. J. Collier. The leading institutions were the Chinese Academy of Agricultural Sciences, followed by the State University System of Florida and the University of Florida. The study maps the significant research domains on heat stress of lactating cows in confinement systems, discusses implications and explanations and highlights emerging trends.

RESUMEN

This study was conducted to describe the building layout and dimensions, characterize the bedding material, and observe the management practices in 42 compost-bedded pack (CBP) barns in Kentucky (USA). The average herd size found in the study was 90 cows and the breeds consisted of Jersey (6.8%), Holstein (72.7%), and mixed (20.5%). The average CBP barn dimensions were 49.1 m (length) by 21.9 m (width). Many of these barns had feed alleys and driveways; overshot ridges with frequent orientation from NE to SW; and green sawdust, kiln-dried sawdust, or a mixture of both as the most common bedding materials. The bed-turning process was performed mechanically at depths of less than 0.25 m, and the loading of fresh material was performed every one to five weeks, varying by season, weather conditions, barn size, and cow density. The average bedding moisture content was found to be 59.0% (wet bulb-w.b.) and ranged from 36.2 to 71.8%. Coliforms were not present in barns that had a higher compost temperature, and the E. coli, Bacillus, and Streptococcus counts were higher in the barns that had a lower moisture content. In conclusion, it was observed that heterogeneous management was used among the barns and that the producers were satisfied with the compost barn system.

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The objective of this study was to evaluate the main scientific studies addressing the topic of compost barns in recent years, highlighting the main journals, authors, countries, organizations, and keywords associated with the publications and trends in this type of research through a bibliometric analysis. For this analysis, publications (articles and literature reviews) addressing compost barns were obtained from the Scopus and Web of Science databases. A total of 108 studies published between 2007 and April 2022 were included. A greater number of publications was observed starting in 2017, with 2021 having the largest number of publications. The Journal of Dairy Science was the most highly cited journal. Marcia I. Endres was the author with the greatest academic impact. The most influential country was the United States, followed by Brazil. Among the organizations that have published studies on compost barns, the Federal University of Lavras, and the University of Florence had the largest numbers of publications. In conclusion, this bibliometric analysis allowed us to evaluate the scientific evolution, research, and publishing tendencies of studies on the compost barn animal housing system, and the results make it possible to deduce current trends in scientific research and publications.

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The mapping of pastures can serve to increase productivity and reduce deforestation, especially in Amazon Biome regions. Therefore, in this study, we aimed to explore precision agriculture technologies for assessing the spatial variations of soil pH and biomass indicators (i.e., Dry Matter, DM; and Green Matter, GM). An experiment was conducted in an area cultivated with Panicum maximum (Jacq.) cv. Mombaça in a rotational grazing system for dairy buffaloes in the eastern Amazon. Biomass and soil samples were collected in a 10 m × 10 m grid, with a total of 196 georeferenced points. The data were analyzed by semivariogram and then mapped by Kriging interpolation. In addition, a variability analysis was performed, applying both the Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI) derived from satellite remote sensing data. The Kriging mapping between DM and pH at 0.30 m depth demonstrated the best correlation. The vegetative index mapping showed that the NDVI presented a better performance in pastures with DM production above 5.42 ton/ha-1. In contrast, DM and GM showed low correlations with the NDWI. The possibility of applying a variable rate within the paddocks was evidenced through geostatistical mapping of soil pH. With this study, we contribute to understanding the necessary premises for utilizing remote sensing data for pasture variable analysis.

RESUMEN

The thermal, chemical, and physical properties of compost bedding materials play an important role in every phase of compost production. Based on this, we aimed to assess the thermal, chemical and physical properties of bedding materials for compost-bedded pack (CBP) barns. The database for this study was registered from 42 CBP barns, distributed throughout the state of Kentucky (USA). The thermal conductivity showed a linear relationship with moisture content and bulk density, while thermal resistivity decreased with increasing particle size. The bedding moisture average was 46.8% (±11.5). The average finer index (p < 0.05) was the highest weight percentage (30.1%) in the samples studied. Water-holding capacity (WHC) increased with increasingly fine particle size. The higher bulk density value was 3.6 times that of the lowest bulk density value. The chemical characterization of the bedding material provided the following results: 42.7% (±3.8%) C, 1.6% (±0.4%) N, and 28.2 (±8.0) C:N ratio. However, thermal properties are strongly dependent on particle size. Producers can use the bedding material as fertilizer in their crops, due to the chemical characteristics of the materials. Beds with good physical and chemical properties improve their moisture content.

RESUMEN

The objective of this study was to evaluate and characterize the dependence and the spatial and temporal distribution of variables and indices of the thermal environment in an open compost-bedded pack barn system with positive-pressure ventilation (CBPPV) during the winter period. The study was conducted in a CBPPV system located in the Zona da Mata region, Minas Gerais, Brazil. The indoor environment was divided into a mesh composed of 55 equidistant points, where data on dry-bulb air temperature (tdb) and relative humidity (RH) were collected. The collected data were divided into four periods-dawn, morning, afternoon, and night-and mean values were obtained. To evaluate the thermal microenvironment, the temperature and humidity index (THI) and the specific enthalpy of air (h) were used. For spatial dependence analysis, geostatistical techniques were applied. Through the results, a strong spatial dependence was verified for all variables evaluated. Through THI and h maps, conditions of thermal comfort were found for dairy cattle. The highest values of tdb, THI, and h were recorded in the afternoon period in the northwest region of the facility (tdb = 23.2 °C, THI = 69.7, and h = 50.9 kJ∙kg of dry air-1).

RESUMEN

Evaporative cooling is one of the most efficient techniques to reduce heat stress in cows in agricultural facilities. Additionally, compost-bedded pack barn has been shown to improve the welfare and production of cows. Two techniques were combined and analysed by developing a computational fluid dynamics (CFD) model of a tunnel-ventilated compost-bedded packed barn that integrated the heat and airflow dynamics of an evaporative pad cooling system. This allowed us to study the distribution of dry-bulb temperature, relative humidity and airflow velocity inside the barn based on the external environmental conditions, thickness of the pad, water temperature and specific manufacturer characteristics of the pad, providing optimal cooling pad location, size and operating conditions in the barn. Employing experimental data the CFD model was validated showing good agreement. The Equivalent Temperature Index for dairy Cattle (ETIC) was used to determine the level of stress of the cows considering the airflow velocity. It was found a moderate stress due to high relative humidity and low airflow velocity. From the predicted results, it was recommended to increase the airflow velocity above 3 m s-1 when simultaneously the external dry-bulb temperature and relative humidity exceed 30 °C and 55%, respectively, simultaneously. Additionally, installation of baffles at the pad outlet to drive the airflow to the floor was suggested to improve the drying of the compost-bedded closed to the pads, where a low airflow velocity region was established.

RESUMEN

In this study, we aimed to assess the spatial variability of microclimate inside a closed compost-bedded pack barn (CBP) with a negative ventilation system during summer and winter. The research was carried out in a CBP located in the Zona da Mata region, Minas Gerais, Brazil. For each of the stations analyzed, the following environmental mean variables observed inside a CBP were measured: air dry-bulb temperature (tdb), air relative humidity (RH), and windspeed, Temperature-Humidity index, and specific enthalpy. The kriging maps showed that the most critical housing conditions in the thermal environment were found, mainly, from the central part of the CBP, close to the exhaust fans. The analyses also pointed out that the system presented temperature gradients along the length, up to 3°C. During the summer afternoon, the entire region of the CBP was in a discomfort situation (tdb>26°C; RH>75%). During the winter, the measured environmental data remained within the comfort zone throughout the facility. However, probably due to the lack of thermal insulation of the material used to close the sides of the CBP, it did not allow spatial thermal uniformity for both seasons. It was also inefficient to keep the animals within the comfort zone for lactating cattle during the critical summer period.

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The aim of this paper was to analyze, using computational fluid dynamics (CFD), a heating system in a commercial broiler house. Data were collected in a broiler house located in the western mesoregion of Minas Gerais, Brazil. The data were collected at 10 a.m. on the seventh day of chicks' life in 16 points inside the house. A tetrahedral mesh was adopted for the simulation, and testing of the mesh yielded a geometry of 485,691 nodes. The proposed model was developed in a permanent state condition to simulate the temperature air inside the broiler house, and all other input variables were considered constant. The applied CFD technique resulted in satisfactory fitting of the air temperature variable along the broiler facility as a function of the input data. The results indicated that the model predicted the environmental conditions inside the broiler house very accurately. The mean error of the CFD model was 1.49%, indicating that the model is effective and therefore that it can be used in other applications. The results showed that the heating system provided favorable thermoneutral conditions for chicks in the biggest part of the broiler house. However, there were some areas with air temperature above and below the thermoneutral zone.

RESUMEN

The objective of this study was to characterize and evaluate the temperature and humidity index (THI) of New Zealand white (NZW) rabbits kept in a rabbit house using geostatistical techniques. Furthermore, we sought to evaluate its relationship with respiratory frequency (RF) and ear surface temperature (EST). The experiment was conducted at the Federal University of Lavras, Brazil. A total of 52 NZW rabbits were used. For the characterization of the thermal environment, the dry bulb temperature (tdb, °C), relative humidity (RH, %), and dew point temperature (tdp, °C) were collected at 48 points in the rabbit house at 6:00 a.m., 12:00 p.m., and 6:00 p.m. for seven days. The RF and EST of the animals was monitored. Subsequently, the THI was calculated and the data were analyzed using geostatistical tools and kriging interpolation. In addition, the RF and EST data were superimposed on the rabbit house's THI data maps. The magnitude of the variability and structure of the THI inside the rabbit house were characterized and the heterogeneity was visualized. Critical THI points inside the rabbit house and in locations where animals with high RF and ESTs were housed were identified, thus providing information about improving the production environment.

RESUMEN

We assessed the cost-effectiveness of the cost center of milk production and identified the components that most affect final costs, estimating a break-even point (kg milk year-¹) as well. The data were collected in a freestall full-confinement system of a dairy cattle farm located in southern Minas Gerais State (Brazil), from January 2016 to December 2017. The cost of milk production was estimated using a method based on the operating and total costs from a cost center involving lactating and dry dairy cows. The cost center of milk production showed to be economically feasible, showing positive gross and net margin results, as well as positive profitability and cost-effectiveness. Total environmental operating cost was on average R$ 0.015 per kg milk, which represented 1.985% of the total operating cost. Effective environmental operating cost was on average R$ 0.0059, which corresponded to 0.7788% of the total operating cost. Finally, total environmental cost was on average R$ 0.0317, representing 3.3280% of the total cost. The most representative items of the effective operating cost were in descending order: animal feed, workforce, animal health, animal production hormone (bovine somatotropin; bST), vehicle maintenance, machines and equipment, maintenance of improvements, electricity, and freestall bedding sand. Average break-even point was 1,104,038.54 kg milk year-¹ or 3,024.76 kg milk day-¹, while average production was 4,271,383.00 kg milk year-¹ and 11,702.42 kg milk day-¹.

Objetivou-se analisar o impacto econômico da adoção de algumas tecnologias ambientalmente corretas no custo de produção do leite e na rentabilidade de um sistema de produção, bem como estimar o custo ambiental e a sua representatividade no custo operacional efetivo, no custo operacional total e no custo total. Especificamente, pretendeu-se, ainda, analisar a rentabilidade do centro de custo produção de leite, identificar os componentes que exercem maiores representatividades sobre os custos finais da atividade e estimar o ponto de equilíbrio (kg de leite ano-¹). Os dados foram coletados no período de janeiro de 2016 a dezembro de 2017 em um sistema de produção de leite localizado ao Sul de Minas Gerais, em confinamento total, do tipo freestall. O custo de produção do leite foi estimado segundo a metodologia do custo operacional e custo total, considerando o centro de custo produção de leite, que envolveu as vacas em lactação e as secas. O centro de custo leite apresentou viabilidade econômica, com margens bruta e líquida, bem como resultado positivo, assim como lucratividade e rentabilidade positivas. O custo ambiental operacional total médio de um quilograma de leite foi estimado em R$ 0,015 e representou 1,985% do custo operacional total; o custo operacional efetivo ambiental médio foi de R$ 0,0059, e correspondeu a 0,7788% do custo operacional total; enquanto que o custo ambiental total médio, estimado em R$ 0,0317, representou 3,3280% do custo total. Os itens componentes do custo operacional efetivo que exerceram maiores representatividades foram, em ordem decrescente, a alimentação, mão-de-obra, sanidade, hormônio produtivo (BST), manutenção de veículos, máquinas e implementos, manutenção de benfeitorias, energia e areia para cama do free stall. O ponto de equilíbrio médio foi estimado em 1.104.038,54 kg de leite ano-¹, ou 3.024,76 kg de leite dia-¹, enquanto que a produção média foi de 4.271.383,00 kg de leite ano-¹ e 11.702,42 kg de leite dia-¹.

Asunto(s)

RESUMEN

We assessed the cost-effectiveness of the cost center of milk production and identified the components that most affect final costs, estimating a break-even point (kg milk year-¹) as well. The data were collected in a freestall full-confinement system of a dairy cattle farm located in southern Minas Gerais State (Brazil), from January 2016 to December 2017. The cost of milk production was estimated using a method based on the operating and total costs from a cost center involving lactating and dry dairy cows. The cost center of milk production showed to be economically feasible, showing positive gross and net margin results, as well as positive profitability and cost-effectiveness. Total environmental operating cost was on average R$ 0.015 per kg milk, which represented 1.985% of the total operating cost. Effective environmental operating cost was on average R$ 0.0059, which corresponded to 0.7788% of the total operating cost. Finally, total environmental cost was on average R$ 0.0317, representing 3.3280% of the total cost. The most representative items of the effective operating cost were in descending order: animal feed, workforce, animal health, animal production hormone (bovine somatotropin; bST), vehicle maintenance, machines and equipment, maintenance of improvements, electricity, and freestall bedding sand. Average break-even point was 1,104,038.54 kg milk year-¹ or 3,024.76 kg milk day-¹, while average production was 4,271,383.00 kg milk year-¹ and 11,702.42 kg milk day-¹.(AU)

Objetivou-se analisar o impacto econômico da adoção de algumas tecnologias ambientalmente corretas no custo de produção do leite e na rentabilidade de um sistema de produção, bem como estimar o custo ambiental e a sua representatividade no custo operacional efetivo, no custo operacional total e no custo total. Especificamente, pretendeu-se, ainda, analisar a rentabilidade do centro de custo produção de leite, identificar os componentes que exercem maiores representatividades sobre os custos finais da atividade e estimar o ponto de equilíbrio (kg de leite ano-¹). Os dados foram coletados no período de janeiro de 2016 a dezembro de 2017 em um sistema de produção de leite localizado ao Sul de Minas Gerais, em confinamento total, do tipo freestall. O custo de produção do leite foi estimado segundo a metodologia do custo operacional e custo total, considerando o centro de custo produção de leite, que envolveu as vacas em lactação e as secas. O centro de custo leite apresentou viabilidade econômica, com margens bruta e líquida, bem como resultado positivo, assim como lucratividade e rentabilidade positivas. O custo ambiental operacional total médio de um quilograma de leite foi estimado em R$ 0,015 e representou 1,985% do custo operacional total; o custo operacional efetivo ambiental médio foi de R$ 0,0059, e correspondeu a 0,7788% do custo operacional total; enquanto que o custo ambiental total médio, estimado em R$ 0,0317, representou 3,3280% do custo total. Os itens componentes do custo operacional efetivo que exerceram maiores representatividades foram, em ordem decrescente, a alimentação, mão-de-obra, sanidade, hormônio produtivo (BST), manutenção de veículos, máquinas e implementos, manutenção de benfeitorias, energia e areia para cama do free stall. O ponto de equilíbrio médio foi estimado em 1.104.038,54 kg de leite ano-¹, ou 3.024,76 kg de leite dia-¹, enquanto que a produção média foi de 4.271.383,00 kg de leite ano-¹ e 11.702,42 kg de leite dia-¹.(AU)

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RESUMEN

Automatic milking systems (AMS) have aroused worldwide interest recently. The first installation was by the company Lely in a project in the Netherlands (its homeland) in 1992. But nowadays, AMS represents a growing reality due to lobby for labor issues, rising costs, difficulty finding well-trained workers, and/ or difficulty keeping people on farms. This work aimed to present a review of the literature on AMS, beginning with a brief history of the evolution of the technology, showing advantages and limitations of its use, and ultimately giving some suggestions. The understanding of the technical functioning and operational running can help farmers and technicians in decision making on the adoption of the new technology. Besides workforce reduction and labor quality promotion, AMS has potential to improve feed conversion to milk, milk quality (with lower SCC), and cow productivity, as well as providing useful data and parameters for better farm management. Potential limitations include high investment costs, changes in milk composition (solids, free fatty acids), and increased risk of ketosis in cows.(AU)

Robôs ordenhadores são uma novidade razoavelmente recente no mundo. O primeiro foi instalado em 1992, pela empresa Lely, em um projeto experimental em seu país de origem, a Holanda. Entretanto, trata-se de uma realidade presente e cada vez maior, pois o problema da mão de obra, em diversos locais do mundo, cada vez mais cara, pouco capacitada e/ou difícil de manter na fazenda, é inexorável. Objetivou-se apresentar uma revisão da literatura sobre a utilização da robótica na ordenha de vacas leiteiras, abordando o funcionamento técnico e operacional, bem como vantagens e limitações de sua utilização, visando auxiliar pecuaristas e técnicos na tomada de decisões em adotar, ou não, essa tecnologia. Apresentou-se, ainda, um breve histórico da evolução dos robôs ordenhadores, bem como algumas considerações finais. Constatou-se que os robôs, além de substituírem mão de obra, possuem o potencial de melhorarem a conversão alimentar para leite, a qualidade do leite (baixar CCS), aumentar a produtividade das vacas e proporcionar dados e parâmetros para uma gestão mais adequada dos números da atividade dentro da fazenda. Dentre as possíveis limitações estão o alto valor de investimento, alterações em sólidos do leite, presença de ácidos graxos livres no leite e aumento nos riscos de cetose nas vacas.(AU)

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The bedding materials used in dairy cow housing systems are extremely important for animal welfare and performance. A wide range of materials can be used as bedding for dairy cattle, but their physical properties must be analysed to evaluate their potential. In the present study, the physical properties of various bedding materials for dairy cattle were investigated, and different fuzzy clustering algorithms were employed to cluster these materials based on their physical properties. A total of 51 different bedding materials from various places in Europe were collected and tested. Physical analyses were carried out for the following parameters: bulk density (BD), water holding capacity (WHC), air-filled porosity (AFP), global density (GD), container capacity (CC), total effective porosity (TEP), saturated humidity (SH), humidity (H), and average particle size (APS). These data were analysed by principal components analysis (PCA) to reduce the amount of data and, subsequently, by fuzzy clustering analysis. Three clustering algorithms were tested: k-means (KM), fuzzy c-means (FCM) and Gustafson-Kessel (GK) algorithms. Furthermore, different numbers of clusters (2-8) were evaluated and subsequently compared using five validation indexes. The GK clustering algorithm with eight clusters fit better regarding the division of materials according to their properties. From this clustering analysis, it was possible to understand how the physical properties of the bedding materials may influence their behaviour. Among the materials that fit better as bedding materials for dairy cows, Posidonia oceanica (Cluster 6) can be considered an alternative material.

RESUMEN

Automatic milking systems (AMS) have aroused worldwide interest recently. The first installation was by the company Lely in a project in the Netherlands (its homeland) in 1992. But nowadays, AMS represents a growing reality due to lobby for labor issues, rising costs, difficulty finding well-trained workers, and/ or difficulty keeping people on farms. This work aimed to present a review of the literature on AMS, beginning with a brief history of the evolution of the technology, showing advantages and limitations of its use, and ultimately giving some suggestions. The understanding of the technical functioning and operational running can help farmers and technicians in decision making on the adoption of the new technology. Besides workforce reduction and labor quality promotion, AMS has potential to improve feed conversion to milk, milk quality (with lower SCC), and cow productivity, as well as providing useful data and parameters for better farm management. Potential limitations include high investment costs, changes in milk composition (solids, free fatty acids), and increased risk of ketosis in cows.

Robôs ordenhadores são uma novidade razoavelmente recente no mundo. O primeiro foi instalado em 1992, pela empresa Lely, em um projeto experimental em seu país de origem, a Holanda. Entretanto, trata-se de uma realidade presente e cada vez maior, pois o problema da mão de obra, em diversos locais do mundo, cada vez mais cara, pouco capacitada e/ou difícil de manter na fazenda, é inexorável. Objetivou-se apresentar uma revisão da literatura sobre a utilização da robótica na ordenha de vacas leiteiras, abordando o funcionamento técnico e operacional, bem como vantagens e limitações de sua utilização, visando auxiliar pecuaristas e técnicos na tomada de decisões em adotar, ou não, essa tecnologia. Apresentou-se, ainda, um breve histórico da evolução dos robôs ordenhadores, bem como algumas considerações finais. Constatou-se que os robôs, além de substituírem mão de obra, possuem o potencial de melhorarem a conversão alimentar para leite, a qualidade do leite (baixar CCS), aumentar a produtividade das vacas e proporcionar dados e parâmetros para uma gestão mais adequada dos números da atividade dentro da fazenda. Dentre as possíveis limitações estão o alto valor de investimento, alterações em sólidos do leite, presença de ácidos graxos livres no leite e aumento nos riscos de cetose nas vacas.

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