Forty Landrace × Large White lactating sows were used to evaluate the effects of cooling of the floor when maintained under high temperature conditions during summer on their productive and reproductive performance. The sows were allocated in a completely randomized design with two treatments with 20 replicates according to parity number and body weight, with each animal being considered an experimental unit. The treatments consisted of cooling of the floor under the sow with water circulation at about 17°C and no cooling. The resulting temperatures of the floor were 27.6 and 35.8°C for the cooled and the control treatments, respectively. The sows from both treatments were exposed to average maximum and minimum environmental temperatures of 26.9 and 20.8°C, respectively. Sows maintained on a cooled floor had a higher feed intake (6.47 vs. 5.61 kg/day; P b 0.01). Despite this higher intake, sows maintained on a cooled floor had higher body weight and body protein losses during the lactation period (P b 0.01) in connection with a higher milk yield and subsequent growth of the litter (2280 vs. 1798 g/day; P b 0.01). There was an effect of treatment on rectal temperature, surface temperatures and respiratory rate (P b 0.01) with lower values in sows submitted to floor cooling. It is concluded that floor cooling under the lactating sow improves its productive and reproductive performance, as well as the performance of its litter.

RESUMO Os adjuvantes têm sido empregados na pulverização

Fifty nine primiparous sows PIC Camborough 23 were distributed in a completely randomized 2 × 2 (with and without floor cooling × two dietary treatments) factorial design with 16 sows/treatment, each sow being considered as an experimental unit. Four replicates of sixteen sows each were used during the trial with the objective of evaluating the effects of floor cooling and the use of dietary amino acid contents on their performance and behaviour during summer. The sows were distributed among the treatments according to body weight and backfat thickness after farrowing. The sows were maintained in the experiment until weaning at 21 days of lactation. The two experimental diets supplied the same levels of crude protein (22%), metabolizable energy (ME; 14.65 MJ/kg) and levels of essential digestible AA relative to digestive lysine and differed according to the digestible lysine to ME ratio (0.75 vs. 0.82 g/MJ of ME). The temperature of the water circulating in the cooled floor was maintained at about 17°C. Based on the average minimum and maximum temperatures (21.5 and 29.5°C) obtained during the experimental trial, it can be assumed that the sows were exposed to periods of heat stress. The replicate and the interaction between replicate and treatment effects on all the measurements were not significant. Similarly, no effect of diet or interaction between diet and floor cooling system was found for all criteria measured. An effect (P b 0.05) of floor cooling on average daily feed intake was observed and floor cooling sows showed a higher average (P b 0.05) digestible lysine (61.5 vs. 51.8 g/d) and ME (78.2 vs. 65.9 MJ/d) intakes. The sows submitted to floor cooling showed, consistently, higher absolute values for average weight (+ 8.5 kg) and backfat (+ 0.75 mm) at weaning, compared with the control sows. The sows submitted to the cooled floor showed a shorter (P b 0.01) weaning-to-oestrus interval. The piglet and litter's daily weight gain (DWG), average weight at weaning (AWW) and total weight gain during lactation (TWG) were higher (P b 0.01) for the floor cooling sows. The floor cooling sows showed a higher (P b 0.01) daily milk production. The respiratory rate and rectal temperature values were lower (P b 0.01) for the floor cooling sows. There were differences (P b 0.01) on the cutaneous temperatures measured on the different parts of the sow's body, with the animals submitted to the cooled floor having lower values. The sows submitted to floor cooling spent less (P b 0.01) time in lateral recumbency inactive, more time nursing (P b 0.05) and more time feeding (P b 0.01) compared with control sows. The floor cooling under the sows increased daily feed intake and lysine intake, leading to a lower body weight loss, a lower weaning-to-oestrus interval and also improved nursing behaviour of the sows, leading to a higher milk production and, consequently, higher weight gains of piglets and litter during the lactation period.

A escolha e o uso adequado de bicos de pulverização são essenciais para a correta aplicação de agrotóxicos. Este trabalho teve como objetivo avaliar o espectro de gotas de bicos de pulverização hidráulicos de jato plano padrão e de jato cônico vazio, com diferentes vazões nominais. Em ambiente controlado, avaliou-se o espectro de gotas por meio de um analisador a laser de gotas em tempo real, nas faixas de pressão de 200 a 400 kPa para os bicos de jato plano, e de 400 a 600 kPa para os bicos de jato cônico vazio. Realizou-se também um estudo teórico sobre a distância horizontal percorrida por gotas de tamanho conhecido. Os bicos de jato cônico vazio apresentaram gotas de menor tamanho em relação aos de jato plano e, por isso, proporcionaram maior densidade de gotas depositadas sobre a superfície-alvo. Todos os bicos apresentaram densidade de gotas superior a 110 gotas cm-2. No entanto, o potencial de deriva foi alto, principalmente o dos bicos de jato cônico, requerendo estratégias para sua redução. É possível estimar a distância horizontal percorrida por gotas de tamanho conhecido.

This study aimed to develop artificial neural networks for the estimation of tractor fuel consumption during soil preparation, according to the adopted system. The multilayer perceptron network was chosen. As input data: the soil mechanical penetration resistance, the mobilized area by implements, the working gear and the tractor engine speed. The number of layers and neurons varied to form different architectures. The adjustment was verified based on various statistical criteria. The values estimated by the networks did not differ significantly from those obtained experimentally. The conclusion was that the networks showed adequate reliability and accuracy to predicting the fuel consumption in each tillage system, in function of the input data and this can be a useful tool for planning and management of agricultural operations.