ABSTRACT Lettuce is a leafy vegetable sensitive to salinity, and under saline stress conditions it presents nutritional imbalance, mainly in calcium absorption. Thus, the objective was to evaluate the effect of enriching the nutrient solution with calcium nitrate in solutions prepared with saline water in the lettuce crop. A completely randomized design was used, with five treatments and four replicates. The treatments were represented by five nutrient solutions [S1 - standard nutrient solution (SNP); S2 - SNP + NaCl (3.5 dS m-1); S3 - S2 + Ca (NO3)2 (50% = 6.86 mmol L-1); S4 - S2 + Ca(NO3)2 (100% = 9.15 mmol L-1); S5 - S2 + Ca(NO3)2 (150% = 11.43 mmol L-1)] in lettuce from the curly group, cv. Elba. After preparing the nutrient solutions, the solutions had the following electrical conductivities: 1.8 (S1); 4.8 (S2); 5.4 (S3); 6.0 (S4); 6.6 (S5) dS m-1. Variables of growth, nutrition and postharvest quality of lettuce were evaluated. With the exception of stem diameter, number of total leaves, plant pH and vitamin C content, the other variables were affected by the extra addition of Ca(NO3)2 in the nutrient solutions. The lettuce cv Elba grown in coconut fiber is tolerant to the salinity of 4.8 dS m-1 (S2). In conditions where the use of saline water with 3.5 dS m-1 for the preparation of the nutrient solution is unavoidable, the use of extra doses of Ca(NO3)2 in the lettuce crop is not recommended.

RESUMO A alface é uma hortaliça folhosa sensível à salinidade, e em condições de estresse salino apresenta crescimento reduzido e desequilíbrio nutricional, principalmente na absorção de cálcio. Assim, objetivou-se avaliar o efeito do enriquecimento da solução nutritiva com nitrato de cálcio em soluções preparadas com água salina na cultura da alface. Utilizou-se o delineamento inteiramente casualizado, com cinco tratamentos e quatro repetições. Os tratamentos foram representados por cinco soluções nutritivas [S1 - solução nutritiva padrão (SNP); S2 - SNP + NaCl (3,5 dS m-1); S3 - S2 + Ca(NO3)2 (50% = 6,86 mmol L-1); S4 - S2 + Ca(NO3)2 (100% = 9,15 mmol L-1); S5 - S2 + Ca (NO3)2 (150% = 11,43 mmol L-1)] em alface do grupo crespa, cv. Elba. Após o preparo das soluções nutritivas, as soluções apresentaram as seguintes condutividades elétricas: 1,8 (S1); 4,8 (S2); 5,4 (S3); 6,0 (S4); 6,6 (S5) dS m-1. Foram avaliadas variáveis de crescimento, nutrição e qualidade pós-colheita da alface. Com exceção do diâmetro do caule, número de folhas totais, pH da planta e teor de vitamina C, as demais variáveis foram afetadas pela adição extra de Ca(NO3)2 nas soluções nutritivas. A alface cv. Elba cultivada em fibra de coco é tolerante à salinidade de 4,8 dS m-1 (S2). Em condições onde o uso de água salina com 3,5 dS m-1 para o preparo da solução nutritiva é inevitável, não é recomendado o uso de doses extras de Ca(NO3)2 na cultura da alface.

ABSTRACT This study aimed to characterize the performance of three electrochemical ammonia sensor modules (MQ137, FECS44-100, and MIX2801) in comparison to standard equipment (iPMU) under atmospheric conditions of an open Compost Barn (CB) during the winter period in Brazil. The study was conducted in Cajuri (MG) over three days, collecting data from 06 am to 05 pm on ammonia concentration, temperature, relative humidity, and air velocity in the CB, specifically at the center of the bedding area. The evaluation period was divided into three parts: Period 1 (06 to 09 am); Period 2 (10 am to 01 pm); and Period 3 (02 pm to 05 pm). Recorded data were analyzed using descriptive statistics. It was observed that the greatest discrepancy among the readings occurred in Period 1 (for all sensor modules and the iPMU), due to air saturation conditions. In Periods 2 and 3, readings from the sensor modules closely matched those recorded by the iPMU. Throughout all periods, the MIX2801 showed the most significant discrepancies compared to the iPMU, whereas the MQ137 was the closest to the standard equipment. This finding suggests that the MQ137 is a viable option for use in CB facilities.

RESUMO Objetivou-se com este trabalho avaliar o bem-estar e a distribuição espacial dos níveis de ruído no interior de uma maternidade de suínos durante as três primeiras semanas de vida dos animais. A avaliação das condições climáticas, realizada através da temperatura de bulbo seco (Tbs), umidade relativa (UR) e índice de temperatura do globo negro e umidade (ITGU), permitiu observar que o tipo de sistema de aquecimento influenciou as condições do ambiente, assim como a utilização do sistema de climatização não garantiu condições de conforto aos leitões. A análise da distribuição espacial dos níveis de ruído, realizada por meio da técnica de geoestatística, possibilitou verificar a ocorrência de variabilidade espacial no interior da instalação. As maiores frequências dos níveis de ruído concentram-se entre 60 e 70 dB. Os valores médios de ITGU situaram-se fora da faixa de conforto térmico para os leitões em todos os sistemas testados.

ABSTRACT The aim of this study was to evaluate the welfare and spatial distribution of noise levels in a swine nursery during the first three weeks of animal’s life. The climatic conditions were evaluated through the dry-bulb temperature (Tdb), relative humidity (RH) and black globe temperature and humidity index (BGHI) and allowed us to observe that the heating system influenced the conditions in the environment, and the use of the air conditioning system did not guarantee animal’s comfort conditions. The analysis on the spatial distribution of noise levels was performed using geostatistics and demonstrated the occurrence of spatial variability inside the facilities. The highest frequencies of noise levels were concentrated between 60 and 70 dB, and the highest noise values were observed near the fans. The mean BGHI values were below the thermal comfort range for piglets in all systems tested.

ABSTRACT The current heating system for piglets in the farrowing usually uses incandescent lamps and, in some cases, heated floors with electric resistances, which in most cases generates a high energy cost. Thus, the implantation of systems that use renewable energies in the heating of piglets can allow the thermal comfort of the animals without reducing the productive development. The objective of this research was to evaluate a computer model in Computational Fluid Dynamics (CFD), which predicts surface temperature in the heating system of a farrowing house. The study was conducted during the summer season on the swine sector of Federal University of Lavras, Brazil. For this study, a prototype solar heater using alternative materials (ASWH) was developed and compared with a conventional solar water heater (CSWH). Two floors were built of cement to test both heating systems and four thermocouple sensors (K type) with digital display were used in each system to test and evaluate the heating efficiency. Based on the results, the average surface temperature in the ASWH and the CSWH treatments was 27.9 ± 2.6 °C and 27.1 ± 1.9 °C, respectively. Therefore, the experimental data showed no significant differences from the data obtained by the model, enabling the conclusion that it is suitable for predicting the thermal conditions of this type of heating system and could be used in swine factories to predict energy consumption. Thus, this computational model can be used as a useful tool for the design and selection of heating systems used in swine maternity systems.