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Simple Summary: Exposure to thermal stress can negatively impact an animals' overall welfare, resulting in decreased body condition, slower growth rates, and in severe cases, mortality. Understanding the thermal comfort of pigs can help producers reduce thermal stress and improve the overall well-being of these animals. To understand pigs' thermal comfort, this study utilized temperature preference with weaned pigs by allowing them to select from a range of temperatures within a thermal apparatus. However, temperature preference is complicated given that a variety of factors can influence thermal comfort. Previous research has indicated that temperature preference is altered based on the number of individuals tested as this can alter their thermal comfort. Social aggregation, through huddling, results in greater heat conservation and animals find cooler temperatures more comfortable. Thus, this study looked at how social groups and different body weight could influence the temperature preference of pigs. Results showed that individual pigs preferred warmer temperatures compared to those in groups of 2 and 4, and that heavier pigs preferred cooler temperatures compared to medium- and lightweight pigs. This study demonstrates that a greater number of individuals perceive a cooler temperature as being within their comfort zone, whereas an individual does not have access to the thermal benefits of social aggregation. Housing pigs within their thermal comfort zone positively impacts productivity and performance. However, fundamental information on behavioral thermoregulatory responses of individual and group-housed pigs is meager. As a gregarious species, pigs prefer to be near one another, touching and often huddling. As pigs huddle together, they decrease their heat loss to the environment by decreasing exposed surface area and increasing mass. Additionally, pigs gain weight rapidly as they age. As an individual grows, their ability to withstand lower temperatures increases. We hypothesized that group size would alter pig thermal preference and that thermal preference would change based upon body weight. Thirty-six groups of pigs (n = 2 pigs/group) were tested in a factorial design based on group size (1, 2, or 4) and weight category (small: 5.20 ± 1.15 kg; medium: 8.79 ± 1.30 kg; and large: 13.95 ± 1.26 kg) in both sexes. Treatment groups were placed inside a chamber with a controlled thermal gradient (4.6 m × 0.9 m × 0.9 m; L × W × H) that ranged in temperature from 18 to 30 °C. Pigs habituated to the gradient for 24 h. The following 24 h testing period was continuously video recorded and each pig's location during inactivity (~70% daily budget) within the thermal apparatus was recorded every 10 min via instantaneous scan sampling. Data were analyzed using a GLM and log10 + 0.001 transformed for normality. Tukey tests and Bonferroni-corrected custom tests were used for post hoc comparisons. Peak temperature preference was determined by the maximum amount of time spent at a specific temperature. Both group size (p = 0.001) and weight category (p < 0.001) influenced the thermal location choice of pigs. Individual pigs preferred 30.31 °C, which differed from a group of 2 (20.0 °C: p = 0.003) and 4 pigs (20.0 °C: p < 0.001). The peak temperature preference of the small pigs (30.2 °C) differed from the large pigs (20.0 °C: p < 0.001) but did not differ from the medium-sized pigs (28.4 °C: p > 0.05). Overall, heavier pigs and larger groups preferred cooler temperatures. [ABSTRACT FROM AUTHOR]

Simple Summary: This study evaluated the effects of exposure of the porcine fetus to in utero heat stress (IUHS) during the first half of gestation on carcass and meat quality attributes when market weight was reached. Pigs exposed to IUHS had lower head and heart weights at slaughter compared to the thermoneutral group. Most measures of carcass quality were not impacted by the treatments, but lower loin muscle area was observed for IUHS carcasses. Additionally, the loins from the heat stressed pigs were found to be tougher, regardless of the duration of aging. Accordingly, minimizing heat stress experienced by gestating pigs would be considered an important factor in improving both yield and quality of pork production systems. This study evaluated the impacts of in utero heat stress (IUHS) on the carcass and meat quality traits of offspring when market weight was reached. Twenty-four F1 Landrace × Large White gilts were blocked by body weight and allocated among thermoneutral (IUTN) or IUHS treatments from d 6 to d 59 of gestation. The offspring were raised under identical thermoneutral conditions, and gilts (n = 10/treatment) at market weight (117.3 ± 1.7 kg) were harvested. At 24 h postmortem, the loins (M. longissimus lumborum) were obtained, and sections were allocated among 1 d and 7 d aging treatments at 2 °C. Carcasses from IUHS pigs had lower head and heart weights (p < 0.05), as well as decreased loin muscle area (p < 0.05) compared to IUTN pigs. Loins from the IUHS group had a higher shear force value than the IUTN group (p < 0.05). Treatments had no other impacts on carcass and meat quality traits (p > 0.05), and Western blots suggested increased toughness of IUHS loins would not be attributed to proteolysis. These results suggest minimizing IUHS during the first half of gestation may be beneficial in improving pork yield and quality, though in general the effects of IUHS would be minimal. [ABSTRACT FROM AUTHOR]

Simple Summary: Extreme heat events put pigs at a greater risk for acute heat stress (HS) and increase intestinal permeability and bacterial translocation, resulting in greater inflammatory cytokine production and, subsequently, reduced growth performance. To combat the negative effects of HS, a quick return of body temperature to euthermia is necessary. However, the return of body temperature to euthermia can be delayed by feed access during recovery, which may have detrimental effects on intestinal health and future growth performance in pigs. Therefore, the study objective was to determine whether feed removal during and after an acute HS event would improve short-term growth performance and reduce circulating cytokines in finishing pigs. We hypothesized that feed removal during an acute HS event would result in a faster return of body temperature to euthermia, reduce the cytokine response, and improve short-term growth performance in finishing pigs. Although body temperature and some cytokines were altered by the HS and feeding treatments, overall, few beneficial effects of feed removal during acute HS were detected in finishing pigs in the present study. The study objective was to evaluate the effects of feed removal during acute heat stress (HS) on the cytokine response and its short-term effect on growth performance in finishing pigs. Thirty-two pigs (93.29 ± 3.14 kg initial body weight; 50% barrows and 50% gilts) were subjected to thermoneutral (TN; 23.47 ± 0.10 °C; n = 16 pigs) or HS (cycling of 25 to 36 °C; n = 16 pigs) conditions for 24 h. Within each temperature treatment, 50% of the pigs were provided with feed (AF; n = 8 pigs/temperature treatment) and 50% of the pigs had no feed access (NF; n = 8 pigs/temperature treatment). Following the 24 h temperature and feeding treatment (TF) period, all pigs had ad libitum access to feed and water and were maintained under TN conditions for 6 d. During the first 12 h of the TF period, gastrointestinal (TGI) and skin (Tsk) temperatures were recorded every 30 min. Serum cytokines were determined at 0, 4, 8, 12, and 24 h during the TF period and on Days 3 and 6 of the post-TF period. Average daily gain (ADG) and average daily feed intake were measured on Days 1, 3, and 6 of the post-TF period. Behavioral data were collected from Days 1 to 6 of the post-TF period. Heat stress increased (p < 0.02) the TGI and Tsk. During the post-TF period, interleukin-1α was greater (p < 0.01) in HS + NF compared to HS + AF and TN + NF pigs. From Days 1 to 2 of the post-TF period, the ADG was reduced (p < 0.01) in TN + AF compared to HS + AF, HS + NF, and TN + NF pigs. In conclusion, feed removal during an acute HS challenge did not reduce the cytokine response or improve short-term growth performance in finishing pigs. [ABSTRACT FROM AUTHOR]

Simple Summary: Transporting weaned piglets from the farrowing house to a nursery or grow/finish site is a common but stressful procedure in United States swine production. Piglets removed from the sow at weaning undergo feed and water withdrawal during transportation, and this stress is further compounded by an abrupt change from a liquid to solid diet upon arrival at their destination. As a result, newly weaned and transported piglets exhibit reduced body weight and signs of dehydration post-transport. Unfortunately, in utero stressors can modify the offspring's physiological, immune, and behavioral responses during postnatal life and may pre-dispose animals to a greater stress response when exposed to novel postnatal procedures, such as weaning and transport. Therefore, the study objective was to evaluate the effects of in utero heat stress on the behavior and physiology of piglets following weaning and transport. We hypothesized that in utero heat-stressed piglets would exhibit a greater behavioral and physiological stress response following weaning and transportation. Additionally, in utero heat-stressed piglets were expected to show physiological signs of metabolic stress immediately following weaning and transport. It was determined that there was some evidence for altered physiological and behavioral responses among in utero heat stressed piglets compared to in utero thermoneutral piglets following weaning and transport. The study objective was to determine whether in utero heat stress (IUHS) affects piglet physiology and behavior following common production practices. A total of 12 gilts were confirmed pregnant and allocated to either heat stress (HS; n = 6) or thermoneutral (TN; n = 6) conditions on day 30–60 of gestation. At weaning (22.5 ± 2.3 days of age), 1 boar and 1 barrow of median weight were selected from each litter and transported for approximately 7 h. Piglets were then blocked into pens (n = 2/pen) by in utero treatment (IUHS (n = 12) or in utero thermoneutral (IUTN, n = 12)) and sexual status (boar (n = 6/in utero treatment) or barrow (n = 6/in utero treatment)). Plasma cortisol, non-esterified fatty acids (NEFA), insulin and glucose were evaluated 1 day prior to transport (pre-transport) and immediately after transport (post-transport). Behavioral data were collected on day 1–7 for 60 min at four different time points each day. In utero heat stressed piglets exhibited reduced cortisol concentrations compared to IUTN piglets immediately post-transport (p = 0.04). Glucose concentrations were not affected by in utero treatment. Insulin concentrations were reduced in IUTN piglets post-transport compared to pre-transport (p = 0.002), but no differences were detected for IUHS pigs. Non-esterified fatty acids tended to be reduced overall for IUHS vs. IUTN pigs (p = 0.08). Overall, IUHS piglets performed more drinking behaviors (p = 0.02) and tended to perform more aggressive behaviors (p = 0.07) than IUTN piglets in the 7 days post-transport. In summary, there was some evidence for altered physiological and behavioral responses among IUHS piglets compared to IUTN piglets following weaning and transport. [ABSTRACT FROM AUTHOR]