Effect of two methods and two anaesthetics for local anaesthesia of piglets during castration

Hair cortisol of pigs in mixed organic farms: the influence of season, breeding system and sex

Introduction

Measurement of hair cortisol concentration (HCC) is a useful tool for assessing the activity of the hypothalamic-pituitary-adrenal axis and thus evaluating the long-term adrenocortical response in different animal species and breeds. Robust indigenous pig breeds are highly adapted to the local environment and are preferred for organic farming, compared to the commercial breeds. We investigated whether seasonality, breeding system (indoor or outdoor) and sex influence HCC of pigs reared on organic farms.

Materials and methods

Fifty-three pigs of the indigenous Slovenian Krškopolje breed were divided into three groups. Group Ind (n = 15) was housed indoors, groups Out-1 (n = 18) and Out-2 (n = 20) were housed outdoors on two different farms for the duration of 9 months. Hair was sampled once per season in the withers area of each pig and HCC was determined using a previously validated ELISA.

Results and discussion

The effect of seasonality was found to be significant and more pronounced in pigs reared outdoors. HCC were highest and varied most in winter for all groups, while they were lowest and varied less in summer and autumn. The highest HCC was measured in group Out-1 in winter, as it was the only group housed outdoors at that time. Group Ind had significantly higher HCC in summer compared to the groups Out-1 and Out-2, which could be due to hair cortisol degradation by the UV light exposure in outdoor groups. Sex had no effect on HCC. Our study suggests that seasonality and housing type influence the HCC of pigs.

Place conditioning as evaluation of affective valence in piglets

The emotional valence of animals is challenging to assess, despite being a key component of welfare. In this study, we attempted to assess emotional valence through memory in 1- and 3-week-old piglets. It was hypothesized that piglets would spend less time in a pen where they experienced a negative event (castration) and more time in a pen where they experienced a positive event (enrichment). A testing apparatus was designed with three equally sized pens: two outer sections serving as treatment pens containing unique visual and tactile cues and a center section remaining neutral. Piglets received either negative or positive condition in one outer treatment pen and a sham treatment in the opposite. Various methods were tested (age of piglets, number and length of conditioning sessions, passive vs. active conditioning). Contrary to expectations, piglets did not decrease their time in the pen associated with the negative condition or increase their time in the pen associated with the positive condition. However, when exposed to the positive condition, results indicate older piglets developed an aversion towards the sham treatment. This study provides methodological groundwork for the application of place conditioning in piglets and highlights the nuances important for the use of cognitive tests to assess animal welfare.

Retention of prions in the polychaete Hediste diversicolor and black soldier fly, Hermetia illucens, larvae after short-term experimental immersion and feeding with brain homogenate from scrapie infected sheep

Finding alternative protein and lipid sources for aquafeeds is crucial for the sustainable growth of fed aquaculture. Upcycling industrial side streams and byproducts using extractive species can reduce waste and help reduce the sector's dependence on fish meal and fish oils. Polychaete worms (Hediste diversicolor) and black soldier fly (Hermetia illucens) larvae (BSFL) are promising candidates for converting waste materials into valuable protein and lipid sources. However, further research and evaluations are needed to ensure the safety and regulatory compliance of these alternative feed sources, especially regarding prions spreading potential in the unlikely case that prions would be introduced in the value chain via feedstocks. In the present investigation, BSFL and juvenile polychaetes that had received a massive dose of scrapie prions through immersion and oral inoculation were found to harbour detectable prions using an ultrasensitive amplification method known as PMCA. This observation suggests that both H. diversicolor and BSFL have the potential to serve as mechanical vectors for prions diseases. However, it is important to note that insects, lacking the prion protein gene, are incapable of propagating prions. Therefore, the quantity of prions present in the larvae will inevitably be lower than the amount of prions they encountered. This is the first study to report on the fate of prions through ingestion by these marine and terrestrial invertebrate species.

Efficacy of inguinal buffered lidocaine and intranasal flunixin meglumine on mitigating physiological and behavioral responses to pain in castrated piglets

Managing castration pain on US sow farms is hindered by the lack of Food and Drug Administration (FDA) approved products for mitigating pain. Previous work assessing flunixin meglumine (FM) efficacy in mitigating castration pain has shown the drug to be effective in pigs, meanwhile, results from previous work evaluating lidocaine efficacy are contradictory. Therefore, the objectives of this study were to determine the efficacy of inguinal buffered lidocaine (BL) and FM in mitigating castration pain in piglets. This study was divided into Part I (physiological response) and Part II (behavioral response). For part I piglets were randomly assigned to the following treatments: T1: (C) Castration plus physiological saline; T2: (S) Sham plus physiological saline; T3: (CL) Castration plus BL; T4: (SL) Sham plus BL; T5: (CF) Castration plus FM; T6: (SF) Sham plus FM; T7: (CLF) Castration plus BL and FM; T8: (SLF) Sham plus BL and FM. Blood was collected 24 h prior to castration, 1 h, and 24 h post castration for cortisol quantification. For Part II another cohort of piglets was enrolled and randomly assign to the following treatments: T1: (C) Castration plus physiological saline and T7: (CLF) Castration plus BL and FM. Behavior scoring was obtained in real-time by observing each piglet for 4-min continuously using Unesp-Botucatu pig acute pain scale (UPAPS) at the following timepoints: 1 h before castration (-1 h), immediately post-castration (0 h), and 3 h post-castration (+3 h). Average cortisol concentrations did not differ at -24 h (P > 0.05) or at 24 h post-castration (P > 0.05) between treatments. At 1 h post-castration, castrated piglets (C and CL) demonstrated greater cortisol concentrations (P < 0.05). Castrated piglets in the CF and CLF group had lower cortisol concentrations compared to C and CL-treated pigs (P < 0.05). For behavioral response, there were no differences between treatments on total UPAPS scores (C and CLF, P > 0.05). Intranasal FM was able to effectively reduce the physiological piglet's response immediately post-castration. Inguinal buffered lidocaine had no effect on the either physiological or behavioral response to pain. Long-term research should focus on refining injection techniques for inguinal BL and consider administration frequency and dosing of intranasal FM to control pain for a longer period post-castration.

Behavior of Piglets in an Observation Arena before and after Surgical Castration with Local Anesthesia

Surgical castration of piglets is generally recognized as a painful procedure, but there is currently no gold standard for the assessment of pain behavior in piglets. However, pain assessment is essential for evaluating the effectiveness of local anesthetics. In this study, we investigated the efficacy of four local anesthetics in terms of pain relief during and after surgical castration in three sequential study parts. To do so, we filmed 178 piglets before the applied procedures, after injection of the local anesthetic, and up to 24 h after castration (five observation times in total) in an observation arena and compared their behavior before and after castration and between treatments and control groups. The results showed significant differences in the behavior of the piglets before and after castration and between the sham-castrated control group and the control group castrated without anesthesia. The different local anesthesia treatment groups showed diverging differences to the control groups. The most frequently shown pain-associated behaviors of the piglets were changes in tail position and hunched back posture. We observed a reduction but no complete elimination of the expressed pain-associated behaviors after local anesthesia. Several behavioral changes-such as changes in tail position, hunched back posture or tail wagging-persisted until the day after castration. Owing to the limited duration of the effects of the local anesthetics, local anesthesia did not influence long-term pain.

Comparative Study of Pain-Related Responses of Male Piglets up to Seven Days of Age to the Application of Different Local Anaesthetics and Subsequent Castration

Simple Summary

Since 2021, surgical piglet castration must be performed with complete pain elimination according to the Animal Protection Law in Germany. General anaesthesia by isoflurane inhalation, which can be performed by the farmer, or by injection of ketamine and azaperone, which must be performed by a veterinarian, are the options available. At present, local anaesthesia is still under debate because of the lack of proof of complete pain elimination and the pain on injection. We tested three local anaesthetics (procaine, lidocaine, and mepivacaine) at two different doses each. Because pain responses can be masked by reactions caused by handling, the piglets were given superficial isoflurane anaesthesia. The pain on injection to the testes was compared with intramuscular injection, and the effectiveness during castration was compared among the local anaesthetics. Nocifensive movements, respiratory rate, blood pressure, heart rate and its variability as well as electroencephalography (EEG) changes were studied in relation to the painful interventions. Most indicators of nociception point to testicular injection pain being beyond intramuscular injection pain when an effective amount of local anaesthetic was used. However, complete pain elimination could not be achieved during castration under local anaesthesia.

Abstract

To evaluate pain responses to intratesticular and subscrotal injection of three local anaesthetics and their efficacy during castration a randomized controlled study was conducted. In groups of 20 piglets, procaine (2%), lidocaine (2%), or mepivacaine (2%) were administered subscrotal and intratesticularly in two different dosages: 0.5 mL of the original substances or the maximum recommended dosage according to body weight diluted with isotonic saline to a volume of 0.3 mL per each injection site. Two placebo groups received the equivalent volume of isotonic saline. A control group was injected intramuscularly with 0.5 mL isotonic saline for injection pain comparison. Electroencephalographic changes, respiratory rate, heart rate and its variability, blood pressure, and nocifensive movements were assessed in superficial isoflurane anaesthesia. While EEG-changes and linear measures of heart rate variability did not appear conclusive, the low frequency/high frequency (LF/HF) ratio corresponded best with the other pain indicators recorded. The injection of 0.3 mL diluted local anaesthetic per injection site elicited significant fewer signs of pain compared to intramuscular injection of saline. However, pain reduction, but not complete pain elimination, during castration could only be achieved with 0.5 mL of the 2% local anaesthetics per injection site, whereby lidocaine and mepivacaine were the most effective.

Piglets' acute responses to local anesthetic injection and surgical castration: Effects of the injection method and interval between injection and castration

Although applied in some countries, efficacy of local anesthetics based on procaine to mitigate acute responses to piglet castration remains questioned. This paper presents results from a factorial study examining the effects of two methods of injection of a procaine-based drug (intra-funicular, IF, vs. intra-testicular, IT), and four intervals between drug injection and castration (2.5, 5, 10, and 30 min) on acute responses of 3–4 day old piglets. The study involved 597 male piglets, and 13 treatments: surgical castration without anesthesia (CC), local anesthesia followed by castration involving all combinations of injection method and interval, and sham handling separated by the same four intervals (SH). Responses of piglets to drug injection, castration and sham handling were evaluated based on quantification of intra-procedural vocalizations and leg movements, as well as saliva cortisol concentration in samples taken before and after castration. No differences were found between IF and the simpler IT injection method. Intervals of 2.5 or 30 min led to stronger piglet responses than the other intervals. Overall, treatments involving anesthesia led to significantly stronger responses than sham handling, during both injection and castration. All treatments, even sham handling, led to a significant increase in saliva cortisol, with no differences between anesthesia treatments and controls. Based on these results, castration 5–10 min after intra-testicular injection of procaine seems to be preferable as compared to the other treatments tested. However, piglets still showed measurable signs of pain and stress during both injection and castration, while handling alone (including the use of a castration bench) triggered a noticeable stress response. In light of these findings, the overall benefit of the procedure in terms of piglet welfare remains arguable.

Piglets' acute responses to procaine-based local anesthetic injection and surgical castration: Effects of two volumes of anesthetic

Surgical castration of piglets is painful, but practiced routinely in commercial pig production. Procaine-based local anesthetics are used to mitigate piglet pain during castration in some countries. Yet, effects of the volume of anesthetic injected remain under-studied. The volume of drug administered may modulate the pain mitigating effect via variation in intra-testicular pressure at injection, potentially leading to pain or discomfort, as well as variation in the dose of active ingredient administered. The present study investigated the effects of injection with two volumes of a procaine-based local anesthetic, 0.3 vs. 0.5 mL per testis, on acute responses of 3-4 day old piglets. A total of 290 piglets were divided into 5 treatment groups: castration without anesthesia, castration after intra-testicular injection of 0.5 or 0.3 mL of drug per testis, and sham handling with one or two stays in a castration bench. Acute responses to drug injection, castration and sham handling were evaluated based on quantification of intra-procedural vocalizations and foreleg movements, as well as saliva cortisol concentrations before and after castration. Regardless of the volume, injection of anesthetic as well as castration led to significantly stronger responses than sham handling. Responses to the two drug volumes did not differ significantly, and responses to castration following injection of 0.3 mL did not differ from piglets castrated without anesthesia. All treatments, including sham handling, led to a significant increase in saliva cortisol, and no difference was found between anesthesia treatments and sham handling. Overall, the results suggested that injection of 0.5 mL led to better pain mitigation at castration compared to injection of 0.3 mL, but even when the local anesthetic was used, the combined procedures of injection and castration led to intra-procedural signs of pain and stress.

Evaluation of Two Injection Techniques in Combination with the Local Anesthetics Lidocaine and Mepivacaine for Piglets Undergoing Surgical Castration

The present study evaluated the effects of two injection techniques in combination with lidocaine or mepivacaine for piglets undergoing castration. To improve ease of use, a cannula with side holes (one-step fenestrated (F)) was invented to simultaneously deliver a local anesthetic into the testis and scrotum and was compared to a two-step injection technique. The distribution of a lidocaine/contrast agent mixture using the two methods was examined using computed tomography. Piglets were randomly divided into treatment groups: handling, castration without pain relief and castration after lidocaine or mepivacaine injection using the one-step F or two-step method. Acute physiological responses to noxious stimuli were evaluated by measuring the mean arterial blood pressure (MAP), heart rate (HR) and nocifensive movements. Fos protein expression in the spinal dorsal cord was semi-quantitatively analyzed. Both injection techniques achieved similar distribution patterns. The one-step F method was faster and easier. Injection was not associated with significant changes in MAP or HR, but Mepi1 and NaCl elicited significantly increased nocifensive movements. Both techniques significantly reduced MAP and nocifensive movements when the spermatic cords were cut, regardless of the local anesthetic type. Compared to NaCl, only the lidocaine treatments significantly reduced HR during skin incision. Lido2 significantly reduced Fos protein expression.

Effects of gonadectomy on clinical-hematological, metabolic and hormone conditions of cockerels

Gonadectomy (caponization) of cockerels is an important way of increasing their productivity, improving the quality and taste properties of the meat, and obtaining dietary products. The objective of the study was the influence of gonadectomy of cockerels on their clinical condition, morphological composition of blood, hemoglobin content and anabolism in the tissues, their productivity and chemical content of the muscles. In the experiment, we used 30 Adler silver cockerels aged 4 weeks, which were divided into two groups: control (intact) and experimental (gonadectomized) according to the analogue principle, with 15 individuals in each. The experiment lasted for 185 days, including the main period of 175 days. We determined that the body temperature of cockerels after gonadectomy increased as early as days one and three. In the blood of gonadectomized cockerels, the number of leukocytes decreased by 36.3%, thrombocytes – by 24.7%, while hemoglobin concentration, numbers of heterophils, eosinophils, basophils, monocytes and lymphocytes did not change compared with the intact individuals. On days 20 and 185 of the experiment, the concentration of testosterone in the blood plasma of gonadectomized cockerels was lower respectively by 57.1% and 53.1%, whereas no differences were found prior to gonadectomy and on the third day of the experiment. We determined increase in uric acid concentration and decrease in the level of ionizing calcium in blood plasma of gonadectomized cockerels compared with intact individuals, while the content of cortisol, glucose, total protein, triglycerides, cholesterol, total calcium and inorganic phosphorus, and also activities of alkaline phosphatase, alanine aminotransferase and aspartate aminotransferase did not change. Live weight of gonadectomized cockerels in the period from 45 to 105 days of the raising did not change, and was higher by 10.4–17.0% from day 115 to 145, and further remained not different from the control. Thoracic muscles of gonadectomized cockerels contained 1.8 times more fat, while the levels of moisture, dry matter, protein and ash in thoracic and thigh muscles did not change. The conducted studies have revealed the effect of gonadectomy of roosters on clinical-hematological parameters, metabolic processes, productivity of birds and chemical composition of muscles and may be used to improve the production of chicken meat with high dietary and taste properties.