The effects of relative humidity (RH) and high ambient temperature (T) on physiological responses and animal performance were studied using 12 groups (10 gilts per group) in pens inside respiration chambers. The microclimate in the chamber was programmed so that T remained constant within a day. Each day, the T was increased by 2°C from low (16°C) to high (32°C). Relative humidity was kept constant at 50, 65, or 80%. The pigs' average initial BW was 61.7 kg (58.0 to 65.5 kg), and their average ending BW was 70.2 kg (65.9 to 74.7 kg). Respiration rate (RR), evaporative water (EW), rectal temperature (RT), skin temperature (ST), voluntary feed intake (VFI), water-to-feed ratio (rW:F), heat production (HP), and ADG were analyzed. The animals had free access to feed and water. We determined the T above which certain animal variables started to change: the so-called inflection point temperature (IPt) or “upper critical temperature.” The first indicator of reaction, RR, was in the range from 21.3 to 23.4°C. Rectal temperature was a delayed indicator of heat stress tolerance, with IPt values ranging from 24.6 to 27.1°C. For both these indicators the IPt was least at 80% RH (P < 0.05). Heat production and VFI were decreased above IPt of 22.9 and 25.5°C, respectively (P < 0.001). For each degree Celsius above IPt, the VFI was decreased by 81, 99, and 106 g/(pig·d) in treatments 50, 65, and 80% RH, respectively. The ADG was greatest at 50% RH (P < 0.05). Ambient temperature strongly affects the pigs' physiological changes and performance, whereas RH has a relatively minor effect on heat stress in growing pigs; however, the combination of high T and high RH lowered the ADG in pigs. The upper critical temperature can be considered to be the IPt above which VFI decreased and RT then increased. Temperatures of the magnitude of both these IPt are regularly measured in commercial pig houses. We conclude that the upper critical temperatures for 60-kg, group-housed pigs fed ad libitum are between 21.3 and 22.4°C for RR, between 22.9 and 25.5°C for HP and VFI, and between 24.6 and 27.1°C for RT. It is clear that different physiological and productive measurements of group-housed, growing-finishing pigs have different critical temperatures.

Though bad odour has always been associated with animal production, it did not attract much research attention until in many countries the odour production and emission from intensified animal production caused serious nuisance and was implicated in the health problems of individuals living near animal farms. Odour from pig production facilities is generated by the microbial conversion of feed in the large intestine of pigs and by the microbial conversion of pig excreta under anaerobic conditions and in manure stores. Assuming that primary odour-causing compounds arise from an excess of degradable protein and a lack of specific fermentable carbohydrates during microbial fermentation, the main dietary components that can be altered to reduce odour are protein and fermentable carbohydrates. In the present paper we aim to give an up-to-date review of studies on the relationship between diet composition and odour production, with the emphasis on protein and fermentable carbohydrates. We hypothesise how odour might be changed and/or reduced by altering the diet of pigs. Research so far has mainly focused on the single effects of different levels of crude protein and fermentable carbohydrates on odour production. However, also important for odour formation are the sources of protein and fermentable carbohydrates. In addition, it is not only the amount and source of these compounds that is important, but also the balance between them. On the basis of our review of the literature, we hypothesise that odour nuisance from pig production facilities might be reduced significantly if there is an optimum balance between protein and fermentable carbohydrates in the diet of pigs.

Large amounts of airborne microorganisms are emitted from livestock production. These emitted microorganisms may associate with dust, and are suspected to pose a risk of airborne infection to humans in vicinity and to animals on other farms. However, the extent to which airborne transmission may play a role in the epidemic, and how dust acts as a carrier of microorganisms in the transmission processes is unknown. The authors present the current knowledge of the entire process of airborne transmission of microorganisms—from suspension and transportation until deposition and infection—and their relation to dust. The sampling and the mitigation techniques of airborne microorganisms and dust in livestock production systems are introduced as well.

Fouling of the solid lying area in pig housing is undesirable for reasons of animal welfare, animal health, environmental pollution, and labor costs. In this study the influence of temperature on the excreting and lying behavior of growing-finishing pigs of different BW (25, 45, 65, 85, or 105 kg) was studied. Ten groups of 5 pigs were placed in partially slatted pens (60% solid concrete, 40% metal-slatted) in climate respiration chambers. After an adaptation period, temperatures were raised daily for 9 d. Results showed that above certain inflection temperatures (IT; mean 22.6°C, SE = 0.78) the number of excretions (relative to the total number of excretions) on the solid floor increased with temperature (mean increase 9.7%/°C, SE = 1.41). Below the IT, the number of excretions on the solid floor was low and not influenced by temperature (mean 13.2%, SE = 3.5). On average, the IT for excretion on the solid floor decreased with increasing BW, from approximately 25°C at 25 kg to 20°C at 100 kg of BW (P < 0.05). Increasing temperature also affected the pattern and postural lying. The temperature at which a maximum number of pigs lay on the slatted floor (i.e., the IT for lying) decreased from approximately 27°C at 25 kg to 23°C at 100 kg of BW (P < 0.001). At increasing temperatures, pigs lay more on their sides and less against other pigs (P < 0.001). Temperature affects lying and excreting behavior of growing-finishing pigs in partially slatted pens. Above certain IT, pen fouling increases linearly with temperature. Inflection temperatures decrease at increasing BW. Copyright © 2006. . Copyright 2006 Journal of Animal Science

This is a comprehensive review on the pigs’ normal eliminatory behaviour (i.e., defaecation and urination) and pen soiling. This review is aimed primarily at solving issues with pen soiling in current systems, and ultimately at the future design of a well-functioning pig toilet, which we intend to elaborate on in a subsequent publication. In this paper, first, normal elimination is described in relation to what is known about its phylogeny, ontogeny, causation, and function, i.e., according to Tinbergen’s four why questions concerning animal behaviour. Then, pen soiling is described as if it were a medical disorder, highlighting its importance, aetiology, symptoms, diagnosis, pathogenesis, treatment, and prevention. Due to its negative consequences in terms of animal welfare, health, workload, and environmental emissions, possible methods to address pen soiling in current systems are described. Probably, pigs do not choose a specific place to eliminate but rather choose the most comfortable place for resting, and avoid eliminating there. We identified four main strategies to reduce pen soiling: (1) reducing the suitability of the designated elimination area to be used for other functions, especially resting or thermoregulation; (2) improving the suitability of other functional areas in the pen to be used for their specific function, such as resting and activity; (3) reducing the suitability of other functional areas to be used for elimination; and (4) improving the suitability of the elimination area for elimination. These prevention strategies and the encompassing disease framework provide a structured approach to deal with pen soiling in existing systems and to support the future design, development, and implementation of a well-functioning pig toilet that can help to achieve some of the main goals of modern pig production, namely reducing environmental emissions as well as substantially improving pig welfare.

Survival of airborne virus influences the extent of disease transmission via air. How environmental factors affect viral survival is not fully understood. We investigated the survival of a vaccine strain of Gumboro virus which was aerosolized at three temperatures (10°C, 20°C, and 30°C) and two relative humidities (RHs) (40% and 70%). The response of viral survival to four metrics (temperature, RH, absolute humidity [AH], and evaporation potential [EP]) was examined. The results show a biphasic viral survival at 10°C and 20°C, i.e., a rapid initial inactivation in a short period (2.3 min) during and after aerosolization, followed by a slow secondary inactivation during a 20-min period after aerosolization. The initial decays of aerosolized virus at 10°C (1.68 to 3.03 ln % min ⁻¹ ) and 20°C (3.05 to 3.62 ln % min ⁻¹ ) were significantly lower than those at 30°C (5.67 to 5.96 ln % min ⁻¹ ). The secondary decays at 10°C (0.03 to 0.09 ln % min ⁻¹ ) tended to be higher than those at 20°C (−0.01 to 0.01 ln % min ⁻¹ ). The initial viral survival responded to temperature and RH and potentially to EP; the secondary viral survival responded to temperature and potentially to RH. In both phases, survival of the virus was not significantly affected by AH. These findings suggest that long-distance transmission of airborne virus is more likely to occur at 20°C than at 10°C or 30°C and that current Gumboro vaccination by wet aerosolization in poultry industry is not very effective due to the fast initial decay.