Physiological responses and blood gas exchange following long-distance transport of piglets weaned at different ages over unpaved or paved roads

Identification of trailer heat zones and associated heat stress in weaner pigs transported by road in tropical climates

Heat stress is major welfare concern during transport of pigs in tropical climates, which can also lead to direct production costs. This study evaluated the dynamics of heat zones through the load and their relationship with heat stress of weaner pigs during road transport in a tropical climate. Both environmental (e.g. temperature and relative humidity) and physiological (e.g. respiratory frequency and lactate) measures were recorded from four vehicle journeys (70 km distance, 216 weaner pigs within each trailer load) within Ceará, northeastern Brazil. Geostatistics and fluid dynamics simulation techniques were applied to understand the dynamics of heat zones and ventilation patterns the truckload. Statistics based on canonical discriminant analysis and ANOVA were performed to verify the relationship between heat zones and heat stress in pigs. The results showed that, during transport, the generation of heat zones occurred with different magnitudes along the load (P < 0.05), which was harmonized by the ventilation dynamics. There was a heat core with high energy content, in the front region of the lower deck (LD) of the trailer. In this zone, weaners pigs had higher rectal temperature (+1.8 °C temperature difference), respiratory frequency (LD = 94 ± 1.3 breaths/min; UD = 86 ± 1.3 breaths/min), and blood cortisol concentration (LD = 32.9 ± 0.8 ng/mL; UD = 30.18 ± 0.6 ng/mL) (all P < 0.05). Weaners pigs transported in the upper deck (UD) compartments had the highest skin temperature (LD = 38.13 ± 0.3 °C; UD = 38.9 ± 0.22 °C) and the highest mean values of blood lactate (LD = 65.5 ± 1.11 m/M; UD = 71.60 ± 1.19 m/M) and Creatine kinase (LD = 3891.23 ± 69U/L; UD = 4107.43 ± 62U/L) (P < 0.05). Weaners transported in compartments of the LD of trailer were more susceptible to heat stress, while weaners in the UD compartments were more susceptible to physical stress and muscle exhaustion. These results provide additional evidence of heat zones within trailer compartments and highlight the requirement for the planning of pig transport operations in tropical climates to mitigate risks of heat stress.

Physiological responses of pigs to preslaughter handling: infrared and thermal imaging applications

Loading, transport, unloading, lairage and stunning are the principle ante-mortem events that generate negative responses associated with stress in pigs. For this reason, it is important to verify the condition of animals throughout the supply chain in order to ensure their welfare and obtain, at the end of the slaughtering process, high-quality carcases and meat. Several studies have identified the indicators and samples that need to be taken into account to properly measure and evaluate the responses that these animals emit to the stressors involved. However, these procedures must be carried out quickly and by non-invasive means so as not to impede the flow of animals through the operations of loading, transport, unloading and lairage. Therefore, the objective of this review article is to analyse the stressful events that pigs experience during these events and discuss the use of the infrared thermography (IRT) as an alternative tool for measuring stress based on temperature changes on the surface of pigs’ skin. We argue that infrared thermography can be used as a strategy to improve animal welfare during loading, transport, unloading and lairage by preventing fatigue and deaths, and decreasing negative impacts on meat quality, such as pale, soft and exudative (PSE), or dark, firm and dry (DFD) conditions.

Effect of the number of incisions and use of local anesthesia on the physiological indicators of surgically-castrated piglets

The objective of this study was to determine the effect of local anesthesia and the number of incisions performed on the physiological blood profile of piglets after surgical castration. A total of 60 male piglets were divided into five groups of 12 each, based on the surgical method employed and the use, or not, of local anesthesia, as follows: surgical castration using one horizontal incision in both testicles with (C1+L) and without (C1) local anesthesia; surgical castration using two vertical scrotal incisions with and without local anesthesia (C2+L and C2); and control piglets which were removed from their pens and held head-down by their hind limbs for approximately 90 s to simulate castration (SIM). Reference blood samples were drawn 24 h before castration (RV), immediately after surgery or simulated castration (PC), and at 24 and 48 h post-castration, to determine physiological profiles including; pH, hematocrit, glucose, electrolytes, lactate, pCO₂ (mmHg), SO₂ (mmHg), and bicarbonate. Results showed increases in lactate and hematocrit immediately after surgical or simulated castration with decreases in pH, HCO₃- and base excess (BE). Surgical castration produced marked alterations of the physiological profile, detected by reduced pH and HCO₃, higher lactate levels and BE alterations. These changes indicated metabolic acidosis that was greater in the piglets castrated surgically with one horizontal incision than in those castrated with two vertical incisions. More research is needed on the use of lidocaine during surgical castration, as it showed no effect on physiological profile in this study, but did alter hematocrit values.

Physiological responses in horses, donkeys and mules sold at livestock markets

The horse welfare at markets includes fatigue, fear, fasting, dehydration and injuries. However, the scientific literature contains no readily-available information on the physiology responses of equids sold in livestock markets. The objective of the present study was to evaluate the effect of holding in livestock markets on gas exchange, the acid-base balance, energy metabolism, and the mineral and water balance in 4 types of horses (Equus caballus), donkeys (Equus asinus) and mules ((Equus asinus × Equus caballus). To this end, a total of 1,438 equine were utilized, after classification into six groups, as follows: mules, donkeys, culled horses, charrería horses (Mexican rodeo horses), foals, and ponies. The time intervals evaluated were 1 and 5 h. During the study, the animals received only water ad libitum. The physiological blood indicators assessed were: P_vCO₂ (mm Hg) and P_vO₂ (mm Hg) pressure, pH, glucose (mg/dL), lactate (mg/dL), bicarbonate levels (mmol/L), hematocrit (%), Na⁺, K⁺ and Ca²⁺ (mmol/L). The animals that presented the most marked physiological alterations were the mules and donkeys. The mules that remained in the corrals for 1 h presented increases (P < 0.0001) in the values for pO_2, glucose, hematocrit and blood pH, compared to reference values (RV), while the donkeys had increases (P < 0.0001) in glucose and hematocrit values. By the end of the first hour at the exhibition corrals the equine were dehydrated, suffered fatigue, and suffered metabolic and compensatory problems, probably due to the combined effects of a series of factors that include transport and inadequate handling.

Metabolic changes during brief periods of ewe–lamb separation at different ages

The present study evaluated metabolic changes in lambs during three brief periods of ewe–lamb separation, namely 1 min (T1), 10 min (T10) and 60 min (T60). The lambs were divided by age into the following three groups: 15 days (G1 = 40 lambs), 30 days (G2 = 40 lambs) and 60 days (G3 = 40 lambs). The hypothesis to be tested was that breaking the ewe–lamb bond at different ages and for these brief time periods will cause significant metabolic changes in the lambs. To this end, blood samples were taken from the three test groups 24 h before separation to establish reference values (RVs), and again at the end of the three separation times. The following blood variables were analysed for all three study groups: glucose (mg/dL), lactate (mg/dL), calcium (Ca2+, mmol/L), sodium (Na+, mmol/L), potassium (K+, mmol/L), haematocrit (HTC, %), pCO2 (mmHg), pO2 (mmHg), HCO3– (mmol/L) and pH. Results showed that the G1 lambs suffered the greatest metabolic changes for the variables pO2, pCO2, glucose, lactate, pH, HCO3–, Ca2+, Na+, K+ and HCT. With respect to time, the first 10 min of separation from the mother induced marked metabolic changes in the 15-, 30- and 60-day-old lambs, but, at 60 min, the G2 and G3 lambs tended to recover their physiological RVs, while the G1 lambs did not. These findings showed that breaking the ewe–lamb bond immediately generated metabolic changes in the lambs even though they remained in a familiar, habitual environment. They also indicated that the age of the lambs at separation was a significant factor, as the older animals tended to re-establish their RVs after the metabolic changes, likely because their physiological compensating mechanisms are more efficient, or perhaps because the intensity of attachment to the mother decreases with greater age.