Association analysis of HSP90AA1 polymorphism with thermotolerance in tropically adapted Indian crossbred cattle

Raising cattle is a lucrative business that operates globally but is confronted by many obstacles, such as thermal stress, which results in substantial monetary losses. A vital role of heat shock proteins (HSPs) is to protect cells from cellular damage. HSP90 is a highly prevalent, extremely adaptable gene linked to physiological resilience in thermal stress. This study aimed to find genetic polymorphisms of the HSP90AA1 gene in Karan Fries cattle and explore their relationship to thermal tolerance and production traits. One SNP (g.3292 A > C) was found in the Intron 8 and three SNPs loci (g.4776 A > G, g.5218T > C and g.5224 A > C) were found in the exon 11 of 100 multiparous Karan Fries cattle. The association study demonstrated that the SNP1-g.3292 A > C was significantly (P < 0.01) linked to the variables respiratory rate (RR), heat tolerance coefficient (HTC) and total milk yield (TMY (kg)) attributes. There was no significant correlation identified between any of the other SNP sites (SNP2-g.4776 A > G; SNP3-g.5218T > C; SNP4-g.5224 A > C) with the heat tolerance and production attributes in Karan Fries cattle. Haploview 4.2 and SHEsis software programs were used to analyse pair linkage disequilibrium and construct haplotypes for HSP90AA1. Association studies indicated that the Hap3 (CATA) was beneficial for heat tolerance breeding in Karan Fries cattle. In conclusion, genetic polymorphisms and haplotypes in the HSP90AA1 were associated with thermal endurance attributes. This relationship can be utilized as a beneficial SNP or Hap marker for genetic heat resistance selection in cow breeding platforms.

Review: Ruminant heat-stress terminology

With increasing climate variability, there is a rise in the exposure to, and incidence of, ruminant heat stress (HS), increasing the requirement for focused research. As such, precise terminology is crucial to maintain effective communication and knowledge advancement. Despite this, several key terms are currently defined inconsistently, leading to confusion and misinterpretation. This paper examines the historical and contemporary use of the terms 'resistance', 'tolerance', 'resilience', and 'susceptibility' across various disciplines, revealing significant ambiguities that hinder both research and practice. Through this comprehensive review, we propose new definitions for each term as they are used relating to HS, with a focus on ruminant production. Proposed definitions align with current scientific understanding, providing a robust framework for future research and application. As further research is conducted, we hope these definitions can be improved through the inclusion of quantitative measures which align with these classifications. This present review provides definition clarity for common heat abatement terminology, enabling consistency and from this, progress in the field to ameliorate HS for ruminants.

Alleviating Heat Stress in Fattening Pigs: Low-Intensity Showers in Critical Hours Alter Body External Temperature, Feeding Pattern, Carcass Composition, and Meat Quality Characteristics

Heat stress is a significant environmental problem that has a detrimental impact on animal welfare and production efficiency in swine farms. The current study was conducted to assess the effect of low-intensity showers, provided during critical high-temperature hours daily, on body external temperature, feeding pattern, and carcass and meat quality characteristics in fattening pigs. A total of 400 animals (200 barrows and 200 gilts) were randomly allotted in 40 pens. A shower nozzle was installed over 20 pens (half barrows and half gilts) where pigs received a low-intensity shower for 2 min in 30 min intervals from 12 to 19 h (SHO group). Another group without showers was also considered (CON). Feeder occupancy measurement, thermographic measures, and carcass and meat quality parameters were studied. In the periods with higher environmental temperatures, SHO animals showed an increase in the feeder occupancy rate compared to the CON group. A decrease in temperature was observed after the shower, regardless of the anatomical location (p < 0.005). The treatment with showers led to higher values than in the CON group of 4.72%, 3.87%, 11.8%, and 15.1% for hot carcass weight, lean meat yield, and fat thickness in Longissimus Dorsi (LD) and Gluteus Medius muscles, respectively (p < 0.01). Pork from CON showed a 14.9% higher value of drip loss, and 18.9% higher malondialdehyde concentration than SHO (p < 0.01); meanwhile, intramuscular fat content was 22.8% higher in SHO than in CON (p < 0.01). On the other hand, the CON group exhibited higher L* (2.13%) and lower a* and b* values (15.8% and 8.97%) compared to the SHO group. However, the pH20h of the CON group was significantly lower than that of the SHO group (p < 0.001), indicating a softer pH decrease. Related to fatty acids in subcutaneous outer and inner layers and intramuscular fat, the CON group showed higher ΣSFA and lower ΣMUFA and Δ9-desaturase indexes than SHO (p < 0.05). In conclusion, the amelioration of heat stress through showers at critical times should be considered an interesting tool that improves both carcass and meat quality, as well as animal welfare.

Genomic regions, candidate genes, and pleiotropic variants associated with physiological and anatomical indicators of heat stress response in lactating sows

BACKGROUND

Heat stress (HS) poses significant threats to the sustainability of livestock production. Genetically improving heat tolerance could enhance animal welfare and minimize production losses during HS events. Measuring phenotypic indicators of HS response and understanding their genetic background are crucial steps to optimize breeding schemes for improved climatic resilience. The identification of genomic regions and candidate genes influencing the traits of interest, including variants with pleiotropic effects, enables the refinement of genotyping panels used to perform genomic prediction of breeding values and contributes to unraveling the biological mechanisms influencing heat stress response. Therefore, the main objectives of this study were to identify genomic regions, candidate genes, and potential pleiotropic variants significantly associated with indicators of HS response in lactating sows using imputed whole-genome sequence (WGS) data. Phenotypic records for 18 traits and genomic information from 1,645 lactating sows were available for the study. The genotypes from the PorcineSNP50K panel containing 50,703 single nucleotide polymorphisms (SNPs) were imputed to WGS and after quality control, 1,622 animals and 7,065,922 SNPs were included in the analyses.

RESULTS

A total of 1,388 unique SNPs located on sixteen chromosomes were found to be associated with 11 traits. Twenty gene ontology terms and 11 biological pathways were shown to be associated with variability in ear skin temperature, shoulder skin temperature, rump skin temperature, tail skin temperature, respiration rate, panting score, vaginal temperature automatically measured every 10 min, vaginal temperature measured at 0800 h, hair density score, body condition score, and ear area. Seven, five, six, two, seven, 15, and 14 genes with potential pleiotropic effects were identified for indicators of skin temperature, vaginal temperature, animal temperature, respiration rate, thermoregulatory traits, anatomical traits, and all traits, respectively.

CONCLUSIONS

Physiological and anatomical indicators of HS response in lactating sows are heritable but highly polygenic. The candidate genes found are associated with important gene ontology terms and biological pathways related to heat shock protein activities, immune response, and cellular oxidative stress. Many of the candidate genes with pleiotropic effects are involved in catalytic activities to reduce cell damage from oxidative stress and cellular mechanisms related to immune response.

Genomic predictions and GWAS for heat tolerance in pigs based on reaction norm models with performance records and data from public weather stations considering alternative temperature thresholds

Genetic improvement of livestock productivity has resulted in greater production of metabolic heat and potentially greater susceptibility to heat stress. Various studies have demonstrated that there is genetic variability for heat tolerance and genetic selection for more heat tolerant individuals is possible. The rate of genetic progress tends to be greater when genomic information is incorporated into the analyses as more accurate breeding values can be obtained for young individuals. Therefore, this study aimed (1) to evaluate the predictive ability of genomic breeding values for heat tolerance based on routinely recorded traits, and (2) to investigate the genetic background of heat tolerance based on single-step genome-wide association studies for economically important traits related to body composition, growth and reproduction in Large White pigs. Pedigree information was available for 265,943 animals and genotypes for 8686 animals. The studied traits included ultrasound backfat thickness (BFT), ultrasound muscle depth (MDP), piglet weaning weight (WW), off-test weight (OTW), interval between farrowing (IBF), total number of piglets born (TNB), number of piglets born alive (NBA), number of piglets born dead (NBD), number of piglets weaned (WN) and weaning-to-estrus interval (IWE). The number of phenotypic records ranged from 6059 (WN) to 172,984 (TNB). Single-step genomic reaction norm predictions were used to calculate the genomic estimated breeding values for each individual. Predictions of breeding values for the validation population individuals were compared between datasets containing phenotypic records measured in the whole range of temperatures (WR) and datasets containing only phenotypic records measured when the weather station temperature was above 10°C (10C) or 15°C (15C), to evaluate the usefulness of these datasets that may better reflect the within-barn temperature. The use of homogeneous or heterogeneous residual variance was found to be trait-dependent, where homogeneous variance presented the best fit for MDP, BFT, OTW, TNB, NBA, WN and IBF, while the other traits (WW and IWE) had better fit with heterogeneous variance. The average prediction accuracy, dispersion and bias values considering all traits for WR were 0.36 ± 0.05, -0.07 ± 0.13 and 0.76 ± 0.10, respectively; for 10C were 0.39 ± 0.02, -0.05 ± 0.07 and 0.81 ± 0.05, respectively; and for 15C were 0.32 ± 0.05, -0.05 ± 0.11 and 0.84 ± 0.10, respectively. Based on the studied traits, using phenotypic records collected when the outside temperature (from public weather stations) was above 10°C provided better predictions for most of the traits. Forty-three and 62 candidate genomic regions were associated with the intercept (overall performance level) and slope term (specific biological mechanisms related to environmental sensitivity), respectively. Our results contribute to improve genomic predictions using existing datasets and better understand the genetic background of heat tolerance in pigs. Furthermore, the genomic regions and candidate genes identified will contribute to future genomic studies and breeding applications.

The effect of combining green iron nanoparticles and algae on the sustainability of broiler production under heat stress conditions

Background

Natural feed additives in broiler feed contribute to the overall health, productivity, and economic viability of broiler chickens while meeting consumer demands and preferences for natural products. The purpose of this research was to determine the effect of green iron nanoparticles (Nano-Fe) and Halimeda opuntia supplementation in broiler diets on performance, ammonia excretion in excreta, Fe retention in tissues and serum, carcass criteria, and meat quality under hot environmental conditions.

Methods

A total of 256 one-day-old male Ross 308 broiler chicks were randomly assigned to one of four feeding treatments for 42 days. Each treatment had eight replications, with eight chicks per replicate. The treatments were Negative control (CON), positive control (POS) supplemented with 1 g/kg Halimeda opuntia as a carrier, POS + 20 mg/kg Nano-Fe (NFH1), POS + 40 mg/kg Nano-Fe (NFH2).

Results

When compared to CON and POS, dietary Nano-Fe up to 40 mg/kg enhanced (p < 0.001) growth performance in terms of body weight (BW), body weight gain (BWG), and feed conversion ratio (FCR). Nano-Fe had the highest BWG and the most efficient FCR (linear, p < 0.01, and quadratic, p < 0.01) compared to POS. Without affecting internal organs, the addition of Nano-Fe and POS enhanced dressing and reduced (p < 0.001) abdominal fat compared to control (CON). Notably, the water-holding capacity of breast and leg meat was higher (p < 0.001), and cooking loss was lower in broilers given Nano-Fe and POS diets against CON. In comparison to POS, the ammonia content in excreta dropped linearly as green Nano-Fe levels increased. When compared to CON, increasing levels of Nano-Fe levels boosted Fe content in the breast, leg, liver, and serum. The birds fed on POS showed better performance than the birds fed on CON.

Conclusion

Green Nano-Fe up to 40 mg/kg fed to broiler diets using 1 g/kg Halimeda opuntia as a carrier or in single can be utilized as an efficient feed supplement for increasing broiler performance, Fe retentions, carcass characteristics, meat quality, and reducing ammonia excretions, under hot conditions.

Investigating the impact of non-additive genetic effects in the estimation of variance components and genomic predictions for heat tolerance and performance traits in crossbred and purebred pig populations

BACKGROUND

Non-additive genetic effects are often ignored in livestock genetic evaluations. However, fitting them in the models could improve the accuracy of genomic breeding values. Furthermore, non-additive genetic effects contribute to heterosis, which could be optimized through mating designs. Traits related to fitness and adaptation, such as heat tolerance, tend to be more influenced by non-additive genetic effects. In this context, the primary objectives of this study were to estimate variance components and assess the predictive performance of genomic prediction of breeding values based on alternative models and two independent datasets, including performance records from a purebred pig population and heat tolerance indicators recorded in crossbred lactating sows.

RESULTS

Including non-additive genetic effects when modelling performance traits in purebred pigs had no effect on the residual variance estimates for most of the traits, but lower additive genetic variances were observed, especially when additive-by-additive epistasis was included in the models. Furthermore, including non-additive genetic effects did not improve the prediction accuracy of genomic breeding values, but there was animal re-ranking across the models. For the heat tolerance indicators recorded in a crossbred population, most traits had small non-additive genetic variance with large standard error estimates. Nevertheless, panting score and hair density presented substantial additive-by-additive epistatic variance. Panting score had an epistatic variance estimate of 0.1379, which accounted for 82.22% of the total genetic variance. For hair density, the epistatic variance estimates ranged from 0.1745 to 0.1845, which represent 64.95-69.59% of the total genetic variance.

CONCLUSIONS

Including non-additive genetic effects in the models did not improve the accuracy of genomic breeding values for performance traits in purebred pigs, but there was substantial re-ranking of selection candidates depending on the model fitted. Except for panting score and hair density, low non-additive genetic variance estimates were observed for heat tolerance indicators in crossbred pigs.

Genetic parameters for automatically-measured vaginal temperature, respiration efficiency, and other thermotolerance indicators measured on lactating sows under heat stress conditions

BACKGROUND

Genetic selection based on direct indicators of heat stress could capture additional mechanisms that are involved in heat stress response and enable more accurate selection for more heat-tolerant individuals. Therefore, the main objectives of this study were to estimate genetic parameters for various heat stress indicators in a commercial population of Landrace × Large White lactating sows measured under heat stress conditions. The main indicators evaluated were: skin surface temperatures (SST), automatically-recorded vaginal temperature (TV), respiration rate (RR), panting score (PS), body condition score (BCS), hair density (HD), body size (BS), ear size, and respiration efficiency (Reff).

RESULTS

Traits based on TV presented moderate heritability estimates, ranging from 0.15 ± 0.02 to 0.29 ± 0.05. Low heritability estimates were found for SST traits (from 0.04 ± 0.01 to 0.06 ± 0.01), RR (0.06 ± 0.01), PS (0.05 0.01), and Reff (0.03 ± 0.01). Moderate to high heritability values were estimated for BCS (0.29 ± 0.04 for caliper measurements and 0.25 ± 0.04 for visual assessments), HD (0.25 ± 0.05), BS (0.33 ± 0.05), ear area (EA; 0.40 ± 0.09), and ear length (EL; 0.32 ± 0.07). High genetic correlations were estimated among SST traits (> 0.78) and among TV traits (> 0.75). Similarly, high genetic correlations were also estimated for RR with PS (0.87 ± 0.02), with BCS measures (0.92 ± 0.04), and with ear measures (0.95 ± 0.03). Low to moderate positive genetic correlations were estimated between SST and TV (from 0.25 ± 0.04 to 0.76 ± 0.07). Low genetic correlations were estimated between TV and BCS (from - 0.01 ± 0.08 to 0.06 ± 0.07). Respiration efficiency was estimated to be positively and moderately correlated with RR (0.36 ± 0.04), PS (0.56 ± 0.03), and BCS (0.56 ± 0.05 for caliper measurements and 0.50 ± 0.05 for the visual assessments). All other trait combinations were lowly genetically correlated.

CONCLUSIONS

A comprehensive landscape of heritabilities and genetic correlations for various thermotolerance indicators in lactating sows were estimated. All traits evaluated are under genetic control and heritable, with different magnitudes, indicating that genetic progress is possible for all of them. The genetic correlation estimates provide evidence for the complex relationships between these traits and confirm the importance of a sub-index of thermotolerance traits to improve heat tolerance in pigs.

Evaluation of the effect of the indoor environment on the physiological responses of early-gestation sows in a commercial house in China

Objective

The environment influences the sow's health and physiology during gestation. This study was conducted to evaluate indoor environmental parameters and physiological responses of early-gestation sows and investigate the possible methods for assessing the thermal environment in commercial houses.

Methods

A total of 20 early-gestation sows (commercial purebred Yorkshire) with an average body weight of 193.20 ± 3.62 kg were used for this study in winter, spring, summer, and autumn. The indoor environment parameters comprising dry-bulb temperature (T_db), relative humidity (RH), and carbon dioxide (CO₂) were recorded in 30-min intervals. Physiological parameters including heart rate (HR) and respiration rate (RR) of sows were also measured every 30 min. Wet-bulb temperature (T_wb) was calculated using T_db, RH and atmospheric pressure was recorded at a nearby weather station.

Results

The average indoor T_db and RH were 12.98 ± 2.03°C and 80.4 ± 6.4% in winter, 18.98 ± 2.68°C and 74.4 ± 9.0% in spring, 27.49 ± 2.05°C and 90.6 ± 6.4% in summer, and 17.10 ± 2.72°C and 64.5 ± 10.9% in autumn. A higher average concentration of CO₂ was observed in winter (1,493 ± 578 mg/m³) than in spring (1,299 ± 489 mg/m³), autumn (1,269 ± 229 mg/m³), and summer (702 ± 128 mg/m³). Compared with the HR and RR in the optimum environment, high RH in the house led to a significant decrease in both HR and RR (P < 0.05). In addition, a significant decline in HR was also obtained at high temperatures (P < 0.05). A temperature humidity index (THI), THI = 0.82 × T_db + 0.18 × T_wb, was determined for early-gestation sows, and the THI thresholds were 25.6 for HR. The variation in THI in summer showed that heat stress still occurred under the pad-fan cooling system.

Conclusion

This study demonstrated the critical significance of considering physiological responses of early-gestation sows in commercial houses and THI thresholds. We recommend that much more cooling measures should be taken for early-gestation sows in summer.

Evaluation of Four Thermal Comfort Indices and Their Relationship with Physiological Variables in Feedlot Cattle

Climatic data from different years and experiments conducted in Nebraska were used to estimate four comfort thermal indices and to predict the risk of heat stress and its relationship with pen surface temperature (PST). These included the temperature–humidity index (THI), the adjusted THI (THIadj), the heat load index (HLI), and THIPST using pen surface temperature instead of air temperature. Respiration rates (RR), tympanic temperatures (TT), and panting scores (PS) were also collected in each year and from each location. During 2007, mean values of soil temperature, PST, outgoing shortwave radiation, and TT were greater than in 2008 (p < 0.011). However, HLI, relative humidity, and incoming and outgoing long-wave radiation were greater during 2008 (p < 0.012). The TT was positively correlated with THIPST and THIadj (0.75 and 0.70, respectively), whereas RR had a moderate correlation with THI, THIadj, and HLI (0.32, 0.27, and 0.34, respectively; p < 0.001). Thermal comfort indices showed a positive correlation with TT, especially the THIPST. These relationships vary with location. However, all of the thermal indices showed weak relationships with the observed RR. This would confirm the different roles that TT and RR have as indicators of heat stress. The THIPST was the best index for predicting TT across years.

Analysis of the range of drugs registered in the Russian Federation to control parasitic infections in pigs

The purpose of the research is the analysis of the range of antiparasitic drugs for pig breeding as registered in the Russian Federation and included in the State Register of Medicinal Products for Veterinary Use.The control of parasitic diseases is an essential element of veterinary support for animal husbandry, and its constituent part is the use of antiparasitic drugs. The State Register contains more than three hundred drugs to control parasitic infections of animals of various species. Forty-eight drugs are allowed for use in pig breeding. The analysis of drug compositions found that they contained a limited list of compounds as active substances. For example, 17 antiparasitic drugs contained compounds of the avermectin class as active substances (12 of them had ivermectin as the active substance); 8 drugs against endoparasites contained albendazole in their composition. At the same time, the composition of combined drugs lack distinction and is a combination of two or more active substances produced in mono-preparations. To prevent the resistance in parasites, it is advisable to use a minimum required list of drugs which allows the availability of a reserve for drug rotation in the future. Simultaneous or sequential use of different drugs (including insectoacaricides based on neonicotinoids or synthetic pyrethroids to treat premises in the presence of animals) complicates the assessment of the individual drug effect on animal health and can induce immunological stress, which creates favorable conditions for infectious diseases including opportunistic infections.

A behavior and physiology-based decision support tool to predict thermal comfort and stress in non-pregnant, mid-gestation, and late-gestation sows

BACKGROUND

Although thermal indices have been proposed for swine, none to our knowledge differentiate by reproductive stage or predict thermal comfort using behavioral and physiological data. The study objective was to develop a behavior and physiology-based decision support tool to predict thermal comfort and stress in multiparous (3.28 ± 0.81) non-pregnant (n = 11), mid-gestation (n = 13), and late-gestation (n = 12) sows.

RESULTS

Regression analyses were performed using PROC MIXED in SAS 9.4 to determine the optimal environmental indicator [dry bulb temperature (T_DB) and dew point] of heat stress (HS) in non-pregnant, mid-gestation, and late-gestation sows with respiration rate (RR) and body temperature (T_B) successively used as the dependent variable in a cubic function. A linear relationship was observed for skin temperature (T_S) indicating that T_DB rather than the sow HS response impacted T_S and so T_S was excluded from further analyses. Reproductive stage was significant for all analyses (P < 0.05). Heat stress thresholds for each reproductive stage were calculated using the inflections points of RR for mild HS and T_B for moderate and severe HS. Mild HS inflection points differed for non-pregnant, mid-gestation, and late gestation sows and occurred at 25.5, 25.1, and 24.0 °C, respectively. Moderate HS inflection points differed for non-pregnant, mid-gestation, and late gestation sows and occurred at 28.1, 27.8, and 25.5 °C, respectively. Severe HS inflection points were similar for non-pregnant and mid-gestation sows (32.9 °C) but differed for late-gestation sows (30.8 °C). These data were integrated with previously collected behavioral thermal preference data to estimate the T_DB that non-pregnant, mid-gestation, and late-gestation sows found to be cool (T_DB < T_DB preference range), comfortable (T_DB = T_DB preference range), and warm (T_DB preference range < T_DB < mild HS).

CONCLUSIONS

The results of this study provide valuable information about thermal comfort and thermal stress thresholds in sows at three reproductive stages. The development of a behavior and physiology-based decision support tool to predict thermal comfort and stress in non-pregnant, mid-gestation, and late-gestation sows is expected to provide swine producers with a more accurate means of managing sow environments.

Effect of Thermal Stress on Thermoregulation, Hematological and Hormonal Characteristics of Caracu Beef Cattle

This study evaluated the influence of environmental temperature on thermoregulation, hormonal, and hematological characteristics in Caracu cattle. Blood samples, hair length, coat and muzzle colors, rectal (RT), and surface temperatures were collected from 48 males and 43 females before (morning) and after sun exposure for eight hours (afternoon). Infrared thermography (IRT) was used to identify superficial temperature that exhibits a high correlation with RT. Hematological parameters, hormone concentrations, RT, and the superficial temperature obtained by IRT that exhibited the highest correlation with RT were evaluated by variance analysis. Regarding IRT, the lower left side of the body (LS) showed the highest correlation with the RT. Interaction between period and sex was observed for LS, cortisol, and eosinophils. Cortisone, progesterone, and RT were influenced by period and sex. Neutrophils and segmented neutrophils were influenced by the period, which showed the highest concentrations after sun exposure. Platelets, leukocytes, lymphocytes, and monocytes were influenced by sex. Heat stress changes several physiological characteristics where males and females exhibited differences in their responses to heat stress. Furthermore, most characteristics evaluated remained within the regular values observed for taurine Creole breeds, showing that Caracu is adapted to tropical climates.

Stress Concepts and Applications in Various Matrices with a Focus on Hair Cortisol and Analytical Methods

When studying stress in animals, it is important to understand the types of stress and their classification, and how to assess the stress levels in different animal species using different matrices accurately and precisely. The classification of stress types helps to distinguish between good stress (eustress) and bad stress (distress). Hence, first, it is crucial to assess the animal's level of stress in a non-intrusive manner and second to identify the type of stress that is best suited to its environment. Third, it is also important to analyze the obtained samples using a suitable method to increase the validity of stress hormone measurements. Therefore, in this review, we aim to: (1) explain the classification of stress, (2) discuss the wide range of body matrices (e.g., saliva, milk, hair, urine, feces, sweat, fins, etc.) that can be used as samples to evaluate stress levels, as well as their comparisons and limitations, and present the reliable matrices for measuring stress hormones with special emphasis on hair, (3) compare the analytical methods for measuring stress hormones after sample preparation. Despite some literature that does not include hair as a reliable matrix for evaluating stress levels, hair is one of the matrices for measuring long-term stress hormone accumulations. This review discusses some factors that influence the level of stress hormones in the hair. By understanding these issues, the scientific community will not only be able to improve the understanding of stress and biomarker evaluation but also suggest how to deal with the consequences of stress in future research.

Towards the Estimation of Body Weight in Sheep Using Metaheuristic Algorithms from Biometric Parameters in Microsystems

The Body Weight (BW) of sheep is an important indicator for producers. Genetic management, nutrition, and health activities can benefit from weight monitoring. This article presents a polynomial model with an adjustable degree for estimating the weight of sheep from the biometric parameters of the animal. Computer vision tools were used to measure these parameters, obtaining a margin of error of less than 5%. A polynomial model is proposed after the parameters were obtained, where a coefficient and an unknown exponent go with each biometric variable. Two metaheuristic algorithms determine the values of these constants. The first is the most extended algorithm, the Genetic Algorithm (GA). Subsequently, the Cuckoo Search Algorithm (CSA) has a similar performance to the GA, which indicates that the value obtained by the GA is not a local optimum due to the poor parameter selection in the GA. The results show a Root-Mean-Squared Error (RMSE) of 7.68% for the GA and an RMSE of 7.55% for the CSA, proving the feasibility of the mathematical model for estimating the weight from biometric parameters. The proposed mathematical model, as well as the estimation of the biometric parameters can be easily adapted to an embedded microsystem.

Effects of various Cooling Methods and Drinking Water Temperatures on Reproductive Performance and Behavior in Heat Stressed Sows

The purpose of this study is to evaluate the effects of multiple cooling systems and different drinking water temperatures (DWT) on the performance of sows and their hair cortisol levels during heat stress. In this study, the effect of four different cooling systems: air conditioner (AC), cooling pad (CP), snout cooling (SC), and mist spray (MS), and two DWT, namely low water temperature (LWT) and high water temperature (HWT) on 48 multiparous sows (Landrace × Yorkshire; 242.84 ± 2.89 kg) was tested. The experiment is based on the use of eight replicas during a 21-days test. Different behaviors were recorded under different cooling treatments in sows. As a result, behaviors such as drinking, standing, and position change were found to be lower in sows under the AC and CP treatments than in those under the SC and MS treatments. Lying behavior increased under the AC and CP systems as compared with that under the SC and MS, systems. The average daily feed intake (ADFI) in sows and weight at weaning in piglets was higher under the AC, CP, and LWT treatments than under the SC, MS and HWT treatments. Sows subjected to SC and MS treatment showed higher hair cortisol levels, rectal temperature, and respiratory rate during lactation than those under AC and CP treatments. Hair cortisol levels, rectal temperature, and respiratory rate were also higher under the HWT than under the LWT treatment. As per the results of this study, the LWT has no significant effect on any of the behavioral factors. Taken together, the use of AC and CP cooling treatment is highly recommended to improve the behavior and to reduce the stress levels in lactating sows.

Influence of heat stress on intestinal integrity and the caecal microbiota during Enterococcus cecorum infection in broilers

Enterococcus cecorum (EC) is one of the most relevant bacterial pathogens in modern broiler chicken production from an economic and animal welfare perspective. Although EC pathogenesis is generally well described, predisposing factors are still unknown. This study aimed to understand the effect of heat stress on the caecal microbiota, intestinal integrity, and EC pathogenesis. A total of 373 1-day-old commercial broiler chicks were randomly assigned to four groups: (1) noninoculated, thermoneutral conditions (TN); (2) noninoculated, heat stress conditions (HS); (3) EC-inoculated, thermoneutral conditions (TN + EC); and (4) EC-inoculated, heat stress conditions (HS + EC). Birds were monitored daily for clinical signs. Necropsy of 20 broilers per group was performed at 7, 14, 21, and 42 days post-hatch (dph). A trend towards enhanced and more pronounced clinical disease was observed in the EC-inoculated, heat-stressed group. EC detection rates in extraintestinal tissues via culture were higher in the HS + EC group (~19%) than in the TN + EC group (~11%). Significantly more birds were colonized by EC at 7 dph in the HS + EC group (100%) than in the TN + EC group (65%, p < 0.05). The caecal microbiota in the two EC-inoculated groups was significantly more diverse than that in the TN group (p < 0.05) at 14 dph, which may indicate an effect of EC infection. An influence of heat stress on mRNA expression of tight junction proteins in the caecum was detected at 7 dph, where all six investigated tight junction proteins were expressed at significantly lower levels in the heat stressed groups compared to the thermoneutral groups. These observations suggest that heat stress may predispose broilers to EC-associated disease and increase the severity thereof. Furthermore, heat stress may impair intestinal integrity and promote EC translocation.

Electronically controlled cooling pads can improve litter growth performance and indirect measures of milk production in heat-stressed lactating sows

Heat stress (HS) decreases lactation output in sows due to an attempt to reduce metabolic heat production. However, this negatively affects litter growth performance. Therefore, the study objective was to determine whether electronically controlled cooling pads (ECP) would improve indirect measures of lactation output (e.g., total heat production; THP) and litter growth performance in HS exposed sows. Over two repetitions, 12 multiparous (2.69 ± 0.85) lactating sows [265.4 ± 26.1 kg body weight (BW)] and litters were assigned to either an ECP (n = 3/repetition) or a non-functional ECP (NECP; n = 3/repetition) and placed into farrowing crates within indirect calorimeters from d 3.7 ± 0.5 to d 18.7 ± 0.5 of lactation. Litters were standardized across all sows (11.4 ± 0.7 piglets/litter), and sows were provided ad libitum feed and water. All sows were exposed to cyclical HS (28.27 ± 0.26°C nighttime to 33.09 ± 0.19°C daytime). On d 4, 8, 14, and 18 of lactation, indirect calorimetry was performed on each individual sow and litter to determine THP and THP/kg BW 0.75. Body temperature (TB) was measured hourly using vaginal implants, and respiration rate [RR; breaths per minute (bpm)] was measured daily at 0700, 1100, 1300, 1500, and 1900 hrs. Sow feed intake (FI) was assessed daily. Litter weights were obtained at birth, on d 4, 8, 14, and 18 of lactation, and at weaning. Data were analyzed using PROC GLIMMIX with sow and/or litter as the experimental unit. An overall decrease (P < 0.01; 25 bpm) in RR and maximum daily TB (P = 0.02; 0.40°C) was observed in ECP versus NECP sows. An increase in THP (P < 0.01; 20.4%) and THP/kg BW 0.75 (P < 0.01; 23.1%) was observed for ECP when compared to NECP sows and litters. Litter average daily gain and weaning weight was increased (P < 0.05; 25.0 and 19.2%, respectively) for ECP versus NECP litters. No FI differences were observed (P = 0.40) when comparing ECP (5.66 ± 0.31 kg/d) and NECP (5.28 ± 0.31 kg/d) sows. In summary, ECPs improve litter growth, thermoregulatory measures, and bioenergetic parameters associated with greater milk production in lactating sows exposed to cyclical HS.

Behavior Comparison During Chronic Heat Stress in Large White and Creole Pigs Using Image-Analysis

Behavior is a good indicator of animal welfare, especially in challenging environments. However, few studies have investigated how pig behavior changes during heat stress. The current study is a proof-of-concept using Convolutional Neural Network (CNN) models to monitor pig behavior in order to investigate the differences in behavioral response to heat stress of two contrasted breeds: Large White (LW), selected for high performance, and Creole (CR), adapted to tropical conditions. A total of 6 slaughter pigs (3 CR and 3 LW; 22 weeks of age) were monitored from 8:30 to 17:30 during 54 days. Two CNN architectures were used to detect the animal (Yolo v2) and to estimate animal's posture (GoogleNet). Pig postures estimated by the neural network showed that pigs spent more time lying on their side when temperature increased. When comparing the two breeds, as temperature increases, CR pigs spent more time lying on their side than LW pigs, suggesting that they use this posture to increase thermoregulation and dissipate heat more efficiently. This study demonstrates that neural network models are an efficient tool to monitor animal behavior in an automated way, which could be particularly relevant to characterize breed adaptation to challenging environments.

Effects of cooling systems on physiological responses and intestinal microflora in early gestating sows exposed to high-temperature stress

This study was conducted to investigate the effect of cooling systems on reproductive performance, body temperature, blood metabolites, and the intestinal microbiome in early gestating sows exposed to high ambient temperature. In total, 39 pregnant sows (Landrace × Yorkshire; 2 parities) were randomly assigned to and maintained in the following three treatment groups (13 sows per group) over days 0 to 35 of pregnancy: (i) air cooling (AC; 26.87 ± 1.23°C), (ii) water-drip cooling (WC; 28.81 ± 0.91°C), and (iii) a lack of cooling with heat stress (HS; 30.72 ± 0.70°C). Backfat thickness was measured before and after HS. Feces were collected on day 0 and 35 d of the trial for microbiome analysis, whereas blood was taken at day 35 of pregnancy and analyzed. Reproductive performance and physiological responses were identified at day 35. Respiration rate along with rectal and skin temperatures were lower (p < 0.05) in the AC group than in the HS and WC groups. Serum blood urea nitrogen values were increased (p < 0.05) in the WC group compared with those measured in the AC and HS groups. Triiodothyronine was found at greater levels (p < 0.05) in the AC than in the HS group. Reproductive performance was not affected by the cooling systems. At the phylum level, fecal pathogenic Spirochaete and Euryarchaeota were found in higher numbers (p < 0.05) in all groups after HS. Similarly, at the genus level, the amount of Treponema was greater (p < 0.05) in all groups after HS. In conclusion, our results suggest that AC or WC can ameliorate or mitigate the adverse effects of HS on the physiological parameters of pregnant sows reared under high temperatures.

Evaluation of sow thermal preference across three stages of reproduction

The metabolic heat production of modern pigs has increased by an average of 16%, compared with sows of 30 years ago. Therefore, it is likely that temperature recommendations require updating to meet the needs of modern pigs. The objective of this study was to evaluate whether different reproductive stages of sows altered thermal preference and if current recommendations required updating. Twenty multiparous sows (3.4 ± 1.2 parity) in different reproductive stages (nonpregnant: n = 7; mid-gestation: 58.5 ± 5.68 d, n = 6; and late-gestation: 104.7 ± 2.8 d, n = 7) were tested. Thermal preference was individually tested, and sows could freely choose a temperature, using a thermal gradient between 10.4 and 30.5 °C. Sows were given 24 h to acclimate to the thermal apparatus. Before testing began, sows were given daily feed allotment and returned to the apparatus. Video from the 24-h test period was used to record sow behavior (time spent inactive), posture (upright and sternal and lateral lying), and location using instantaneous scan samples every 15 min. Data were analyzed using PROC MIXED procedure in SAS 9.4. A cubic regression model was used to calculate the sow's most preferred temperature based on the location, or temperature, in which they spent the most time. The preference range was calculated using peak temperature preference ±SE for each sow. The reproductive stage altered where sows spent their time within the thermal gradient (P < 0.01). Late-gestation sows preferred cooler temperatures (14.0 °C) than mid-gestation (14.8 °C; P < 0.01) and nonpregnant sows (14.8 °C; P < 0.01). In summary, sow thermal preferences were within the lower half of the current recommended range (10 to 25 °C). This indicates that temperatures at the higher end of the recommended range could be uncomfortable to sows and that the thermal comfort zone of sows may be narrower than recommendations indicate.

The effects of heat stress on the behaviour of dairy cows – a review

Heat stress in livestock is a function of macro- and microclimatic factors, their duration and intensity, the environments where they occur and the biological characteristics of the animal. Due to intense metabolic processes, high-producing dairy cows are highly vulnerable to the effects of heat stress. Disturbances in their thermoregulatory capability are reflected by behavioural, physiological and production changes. Expression of thermoregulatory behaviour such as reduction of activity and feed intake, searching for a cooler places or disturbances in reproductive behaviours may be very important indicators of animal welfare. Especially maintain of standing or lying position in dairy cattle may be a valuable marker of the negative environmental impact. Highly mechanized farms with large numbers of animals have the informatic system can detect alterations automatically, while small family farms cannot afford these type of equipments. Therefore, observing and analysing behavioural changes to achieve a greater understanding of heat stress issue may be a key factor for developing the effective strategies to minimize the effects of heat stress in cattle. The aim of this review is to present the state of knowledge, over the last years, regarding behavioural changes in dairy cows (Bos Taurus) exposed to heat stress conditions and discuss some herd management strategies provided mitigation of the overheat consequences.

Effects of cooled floor pads combined with chilled drinking water on behavior and performance of lactating sows under heat stress

This study was conducted to evaluate whether cooled floor pads combined with chilled drinking water could alleviate negative impacts of heat stress on lactating sows. Thirty sows (Landrace × Yorkshire, Parity = 1 to 6) were housed in individual farrowing stalls in two rooms with temperatures being controlled at 29.4°C (0700-1900 hours) and 23.9°C (1900-0700 hours). Sows in one room (Cool), but not in the other room (Control) were provided cooled floor pads (21-22°C) and chilled drinking water (13-15°C). Behavior of sows (15 sows/treatment) was video recorded during farrowing, and days 1, 3, 7, 14, and 21 after farrowing. Videos were viewed continuously to register the birth time of each piglet, from which total farrowing duration and birth intervals were calculated. The number of drinking bouts and the duration of each drinking bout were registered for each sow through viewing videos continuously for 2 h (1530-1730 hours) each video-recording day. Postures (lying laterally, lying ventrally, sitting, and standing) were recorded by scanning video recordings at 5-min intervals for 24 h each video-recording day, and time budget for each posture was calculated. Rectal temperature and respiration rate were measured for all sows the day before and after farrowing, and then once weekly. Sow and litter performance was recorded. Data were analyzed using the Glimmix procedure of SAS. The cooling treatment did not affect sow behavior or litter performance. Sows in the Cool room had lower rectal temperature (P = 0.03) and lower respiration rate (P < 0.001), consumed more feed (P = 0.03), tended to have reduced weight loss (P = 0.07), and backfat loss (P = 0.07) during lactation than sows in the Control room. As lactation progressed, sows increased drinking frequency (P < 0.001) and time spent lying ventrally (P < 0.0001), standing (P < 0.001), and sitting (P < 0.0001), and decreased time spent lying laterally (P < 0.0001) in both Cool and Control rooms. While cooled floor pads combined with chilled drinking water did not affect sow behavior, they did alleviate heat stress partially, as indicated by decreased rectal temperature, respiration rate, weight, and backfat loss, and increased feed intake in lactating sows.

In utero heat stress alters the postnatal innate immune response of pigs

The effects of in utero heat stress (IUHS) range from decreased growth performance to altered behavior, but the long-term impact of IUHS on postnatal innate immune function in pigs is unknown. Therefore, the study objective was to determine the effects of early gestation IUHS on the immune, metabolic, and stress response of pigs subjected to an 8 hr lipopolysaccharide (LPS) challenge during postnatal life. Twenty-four pregnant gilts were exposed to thermoneutral (TN; n = 12; 17.5 ± 2.1 °C) or heat stress (HS; n = 12; cyclic 26 to 36 °C) conditions from days 6 to 59 of gestation, and then TN conditions (20.9 ± 2.3 °C) from day 60 of gestation to farrowing. At 12 wk of age, 16 IUHS and 16 in utero thermoneutral (IUTN) pigs were selected, balanced by sex and given an intravenous injection of LPS (2 µg/kg BW mixed with sterile saline [SAL] and injected at 2 µL/kg BW) or SAL (2 µL/kg BW). Body temperature was monitored every 30 min, and blood was obtained at 0, 1, 2, 3, 4, 6, and 8 hr following the LPS challenge. Blood samples were analyzed for glucose, insulin, non-esterified fatty acids (NEFA), cortisol, and cytokine concentrations. In addition, white blood cell counts were determined at 0 and 4 hr. Hour 0 data were used as covariates. Body temperature was increased (P < 0.01) in LPS (40.88 ± 0.08 °C) vs. SAL (39.83 ± 0.08 °C) pigs. Eosinophils tended to be decreased overall (P = 0.09; 43.9%) in IUHS vs. IUTN pigs. Glucose concentrations were reduced overall (P = 0.05; 5.9%) in IUHS vs. IUTN pigs. The NEFA concentrations tended to be greater (P = 0.07; 143.4%) in IUHS-LPS pigs compared with all other treatments, and IUTN-LPS pigs tended to have greater (127.4%) circulating NEFA concentrations compared with IUTN-SAL and IUHS-SAL pigs. Cortisol was increased (P = 0.04) in IUHS-LPS compared with IUTN-LPS pigs at 3 hr (21.5%) and 4 hr (64.3%). At 1 hr, tumor necrosis factor α was increased (P = 0.01; 115.1%) in IUHS-LPS compared with IUTN-LPS pigs. Overall, interleukin-1β (IL-1β) and interleukin-6 (IL-6) were greater (P < 0.04; 281.3% and 297.8%, respectively) in IUHS-LPS pigs compared with all other treatments, and IUTN-LPS pigs had increased IL-1β and IL-6 concentrations compared with IUTN-SAL and IUHS-SAL pigs. In summary, IUHS altered the postnatal cytokine, metabolic, and physiological stress response of pigs during postnatal life, which may have negative implications toward the innate immune response of IUHS pigs to pathogens.

Effects of Feed Removal during Acute Heat Stress on the Cytokine Response and Short-Term Growth Performance in Finishing Pigs

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 (T_GI) and skin (T_sk) 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 T_GI and T_sk. 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.

Prospects for sustainable use of the pastoral areas of Australia’s southern rangelands: a synthesis

There is growing recognition of the need to achieve land use across the southern Australian rangelands that accommodates changing societal preferences and ensures the capacity of future generations to satisfy their own preferences. This paper considers the prospects for sustainable use of the pastoral lands based either on continued grazing or emerging, alternative land uses. After an overview of the southern rangelands environment, the status of the pastoral industry, its environmental impacts, and key issues for pastoral management, we propose four principles and 19 associated guidelines for sustainable pastoralism. Although some continued withdrawal of land from pastoralism is anticipated, we expect that pastoralism will continue throughout much of the region currently grazed, particularly in the higher rainfall environments in the east. Within these areas, sustainable pastoral land use should be achievable by the application of four broad management principles, as follows: (1) manage grazing within a risk management framework based on the concept of tactical grazing, (2) develop infrastructure to allow best management of both domestic and non-domestic grazing pressure, (3) incorporate management of invasive native scrub, where required, into overall, ongoing property management and (4) manage grazing to enhance biodiversity conservation at landscape scale. Application of these principles and guidelines will require the development of appropriate policy settings, particularly in relation to kangaroo management, climate change, and natural resource governance, together with innovative approaches to research, development and extension. Policy development will also be required if the new industry of carbon sequestration is to deliver socio-ecological benefits without perverse outcomes. Other emerging industries based on renewable energy or ecosystem services appear to have considerable potential, with little risk of adverse ecological consequences.

The Effect of Climate Change-Induced Temperature Increase on Performance and Environmental Impact of Intensive Pig Production Systems

This study examined climate change impacts (CCI) on productivity of pig production systems, their resource use, environmental impacts and the relevance of potential adaptation options. The impact of increasing temperature and temperature-humidity index (THI) on performance of pigs in confined housing systems was analysed by a meta-analysis. Using climate data for an Austrian site for the period 1981 to 2010, different scenarios (cold year, warm year, hot year, worst case scenario) were modelled and compared. Although significant differences between thermoneutral and heat stress conditions were detected for the analysed traits of growing and finishing pigs, overall performance, resource use (cumulative energy demand) and environmental impacts (global warming, acidification and eutrophication potential) per kg of live mass for finished pigs and reared piglets did not significantly differ between most scenarios. Elements of pig production systems resilient to CCI, which were not considered under performance and environmental impacts (LCA), were addressed in a system analysis that was based on literature and expert knowledge. The most important detected system elements are plants and animals with an appropriate genetic potential, securing the access to inexpensive feed, including land for feed production, securing water supply and the implementation of health plans and measures against diseases associated with CCI.

An Acute, Rather Than Progressive, Increase in Temperature-Humidity Index Has Severe Effects on Mortality in Laying Hens

This study was conducted to evaluate the effects of temperature-humidity index (THI) on the mortality and the panting rates in hens exposed to varying thermal environments. Hens were challenged with an acute elevation in THI in Experiment 1, where dry-bulb temperature and relative humidity were set at ~27°C and 56% at the beginning of the experiment and changed to 36°C and 45% at its conclusion, respectively. In Experiment 2, different groups of hens were exposed to a progressive increase in THI, with similar ranges to those used in the previous experiment. In Experiment 3, the hens used in Experiment 2 were again challenged by THI conditions, the intensity of which ranged between those used in the previous two experiments. In Experiment 4, panting rates were recorded under varying THI. In the last, plasma biochemical profiles were determined in blood taken from hens subjected to experimental conditions similar to those in Experiment 2. When THI was acutely elevated from 24.2° to 32.1°C within 1 h and then maintained over 4.5 h, no mortality was detected in the first hour, but exceeded 95% after 5 h, and reached 100% at 5.5 h. A gradual increase in THI to 31.2°C over 6 h did not result in mortality during the first 3 h. When THI was set below the conditions in Experiment 1 but above those in Experiment 2, mortality was 29% at 4 h, 75% at 5 h, and 79% at 8 h. However, no mortality was detected in their respective control groups. Panting was not observed under 25.3°C and was largely variable under 30°C. However, all hens exhibited panting exceeding 250 counts/min and 60% mortality at 34°C when heat stress continued for a duration of up to 280 min. In Experiment 5, high ambient THI resulted in significant reductions in plasma albumin, amylase and aspartate aminotransferase, compared with those in control group (P < 0.05). These results suggest that an acute elevation of THI has more severe effects on mortality in hens than gradual changes even when temperature and humidity are similar in both cases.

COVID-19 Effects on Livestock Production: A One Welfare Issue

The COVID-19 pandemic highlights that we exist in a global community. From a single city, it spread to 188 countries across the world and infected 30 million people by September 18, 2020. Decades of modeling pandemics predicted potential consequences, but COVID-19's impact on the food supply chain, and specifically livestock production was unexpected. Clusters of cases among workers in meat processing plants evolved quickly to affect human, animal, and environmental welfare in several countries. In processing plants, the hygiene focus is on product quality and food safety. Because of their close proximity to one another, COVID-19 spread rapidly between workers and the lack of sick leave and health insurance likely resulted in workers continuing to work when infectious. In the United States (U.S.) many processing plants shut down when they identified major outbreaks, putting pressure especially on pig and poultry industries. At one point, there was a 45% reduction in pig processing capacity meaning about 250,000 pigs per day were not slaughtered. This resulted in longer transport distances to plants in operation with extra capacity, but also to crowding of animals on farm. Producers were encouraged to slow growth rates, but some had to cull animals on farm in ways that likely included suffering and caused considerable upset to owners and workers. Carcass disposal was also associated with potential biosecurity risks and detrimental effects on the environment. Hence, this is a One Welfare issue, affecting human, animal, and environmental welfare and highlighting the fragility of intensive, high-throughput livestock production systems. This model needs to be re-shaped to include the animal, human, and environmental elements across the farm to fork chain. Such a One Welfare approach will ensure that food production systems are resilient, flexible, and fair in the face of future challenges.

Impacts of heat stress on meat quality and strategies for amelioration: a review

During the summer, high ambient temperature and humidity cause economic loss to the global livestock industry via reduced livestock productivity and increased mortality. The problem of heat stress (HS) is likely to be exacerbated by global warming and climate change. Recent research has shown that HS not only leads to physiological and metabolic perturbations in live animals but can also affect carcass and meat quality characteristics plausibly by altering the rate and extent of postmortem muscle glycolysis and resultant pH. However, these impacts of HS are not consistent across species. Higher incidence of pale soft and exudative (PSE) meat has been reported in poultry. On the contrary, higher incidence of high ultimate pH and dark firm and dry (DFD) meat or no impacts of HS have been reported in sheep and cattle. With the limited data on HS impacts on meat quality of ruminants, it is difficult to explain the exact mechanisms driving these variable impacts. However, it is hypothesized that the severity and duration of HS may lead to variable impacts due to lack of opportunity to adapdate to acute heat exposure. Longer HS exposure may allow ruminants to adapdate to heat and may not record any negative impacts on meat quality. This paper reviews the recent research on impacts of HS on meat quality characteristics and identify the key areas of further research required to better understand these negative impacts to develop strategies for amelioration. In addition, some mitigation strategies of HS have also been discussed which include both managemental and nutritional interventions.

Modulation of rumen fermentation and microbial community through increasing dietary cation-anion difference in Chinese Holstein dairy cows under heat stress conditions

AIMS

The effect of increasing dietary cation-anion difference (DCAD) on rumen fermentation and ruminal microbial community in dairy cows under heat stress (HS) conditions were evaluated.

METHODS AND RESULTS

This study was performed as a two-period cross-over design during the summer season, with eight lactating dairy cows randomly distributed to either a control DCAD diet (CON: 33·5 mEq/100 g DM) or high DCAD diet (HDCAD: 50·8 mEq/100 g DM). Throughout the present study, the temperature and humidity index (THI; 80·2 ± 4·29) was generally elevated above the threshold (THI = 72) that is reported to cause HS in lactating dairy cows. Rumen liquid samples were collected on 15 and 21 d during each 21 d-period. The absolute concentration of ruminal total volatile fatty acid (TVFA) in HDCAD treatment was significantly (P < 0·05) higher than those in the control, whilst the ruminal pH, NH₃ -N, and VFA molar percentages were unaffected through increasing DCAD. Furthermore, the copy numbers of the cellulolytic bacteria Ruminococcus albus and Ruminococcus flavefaciens in rumen fluid significantly (P < 0·05) rose along with the increment of DCAD. Although the Alpha diversity indexes and the bacterial microbiota structure were unaffected, increasing DCAD significantly (P < 0·05) enriched the phylum Fibrobacteres and genus Fibrobacter in the microflora of rumen fluid, whilst the genera Flexilinea and Dubosiella were the most differentially abundant taxa in the control.

CONCLUSIONS

Increasing DCAD under HS conditions resulted in a greater concentration of total VFA without affecting rumen bacteria diversity or structure, although the enrichment of some cellulolytic/hemicellulolytic bacteria was observed.

SIGNIFICANCE AND IMPACT OF THE STUDY

The present study provides information on the modulation of rumen fermentation and microbial community through the increment of DCAD in Holstein dairy cows under HS conditions.

Large-Scale Phenotyping of Livestock Welfare in Commercial Production Systems: A New Frontier in Animal Breeding

Genomic breeding programs have been paramount in improving the rates of genetic progress of productive efficiency traits in livestock. Such improvement has been accompanied by the intensification of production systems, use of a wider range of precision technologies in routine management practices, and high-throughput phenotyping. Simultaneously, a greater public awareness of animal welfare has influenced livestock producers to place more emphasis on welfare relative to production traits. Therefore, management practices and breeding technologies in livestock have been developed in recent years to enhance animal welfare. In particular, genomic selection can be used to improve livestock social behavior, resilience to disease and other stress factors, and ease habituation to production system changes. The main requirements for including novel behavioral and welfare traits in genomic breeding schemes are: (1) to identify traits that represent the biological mechanisms of the industry breeding goals; (2) the availability of individual phenotypic records measured on a large number of animals (ideally with genomic information); (3) the derived traits are heritable, biologically meaningful, repeatable, and (ideally) not highly correlated with other traits already included in the selection indexes; and (4) genomic information is available for a large number of individuals (or genetically close individuals) with phenotypic records. In this review, we (1) describe a potential route for development of novel welfare indicator traits (using ideal phenotypes) for both genetic and genomic selection schemes; (2) summarize key indicator variables of livestock behavior and welfare, including a detailed assessment of thermal stress in livestock; (3) describe the primary statistical and bioinformatic methods available for large-scale data analyses of animal welfare; and (4) identify major advancements, challenges, and opportunities to generate high-throughput and large-scale datasets to enable genetic and genomic selection for improved welfare in livestock. A wide variety of novel welfare indicator traits can be derived from information captured by modern technology such as sensors, automatic feeding systems, milking robots, activity monitors, video cameras, and indirect biomarkers at the cellular and physiological levels. The development of novel traits coupled with genomic selection schemes for improved welfare in livestock can be feasible and optimized based on recently developed (or developing) technologies. Efficient implementation of genetic and genomic selection for improved animal welfare also requires the integration of a multitude of scientific fields such as cell and molecular biology, neuroscience, immunology, stress physiology, computer science, engineering, quantitative genomics, and bioinformatics.

Genomics of Heat Tolerance in Reproductive Performance Investigated in Four Independent Maternal Lines of Pigs

Improving swine climatic resilience through genomic selection has the potential to minimize welfare issues and increase the industry profitability. The main objective of this study was to investigate the genetic and genomic determinism of tolerance to heat stress in four independent purebred populations of swine. Three female reproductive traits were investigated: total number of piglets born (TNB), number of piglets born alive (NBA) and average birth weight (ABW). More than 80,000 phenotypic and 12,000 genotyped individuals were included in this study. Genomic random-regression models were fitted regressing the phenotypes of interest on a set of 95 environmental covariates extracted from public weather station records. The models yielded estimates of (genomic) reactions norms for individual pigs, as indicator of heat tolerance. Heat tolerance is a heritable trait, although the heritabilities are larger under comfortable than heat-stress conditions (larger than 0.05 vs. 0.02 for TNB; 0.10 vs. 0.05 for NBA; larger than 0.20 vs. 0.10 for ABW). TNB showed the lowest genetic correlation (-38%) between divergent climatic conditions, being the trait with the strongest impact of genotype by environment interaction, while NBA and ABW showed values slightly negative or equal to zero reporting a milder impact of the genotype by environment interaction. After estimating genetic parameters, a genome-wide association study was performed based on the single-step GBLUP method. Heat tolerance was observed to be a highly polygenic trait. Multiple and non-overlapping genomic regions were identified for each trait based on the genomic breeding values for reproductive performance under comfortable or heat stress conditions. Relevant regions were found on chromosomes (SSC) 1, 3, 5, 6, 9, 11, and 12, although there were important regions across all autosomal chromosomes. The genomic region located on SSC9 appears to be of particular interest since it was identified for two traits (TNB and NBA) and in two independent populations. Heat tolerance based on reproductive performance indicators is a heritable trait and genetic progress for heat tolerance can be achieved through genetic or genomic selection. Various genomic regions and candidate genes with important biological functions were identified, which will be of great value for future functional genomic studies.

Effects of feed removal on thermoregulation and intestinal morphology in pigs recovering from acute hyperthermia

Feed consumption increases body temperature and may delay a return to euthermia and exacerbate intestinal injury following acute hyperthermia recovery in pigs. Therefore, the study objective was to evaluate the effects of feed removal on body temperature and intestinal morphology in pigs exposed to acute hyperthermia and then rapidly cooled. Twenty-four gilts (78.53 ± 5.46 kg) were exposed to thermoneutral (TN; n = 12 pigs; 21.21 ± 0.31 °C; 61.88 ± 6.93% RH) conditions for 6 h, or heat stress (HS; 38.51 ± 0.60 °C; 36.38 ± 3.40% RH) conditions for 3 h followed by a 3-h recovery period of rapid cooling (HSC;n = 12 pigs; TN conditions and cold water dousing). Within each recovery treatment, one-half of the pigs were provided feed ad libitum (AF; n = 6 pigs per recovery treatment) and one-half of the pigs were not provided feed (NF; n = 6 pigs per recovery treatment). Gastrointestinal (TGI), vaginal (TV), and skin (TSK) temperatures and respiration rate (RR) were recorded every 15 min. Pigs were video-recorded to assess feeding and drinking attempts. Immediately following the 6-h thermal stress period, pigs were euthanized, and intestinal samples were collected to assess morphology. During the HS period, Tv, TGI, TSK, and RR were increased (P < 0.01; 1.63, 2.05, 8.32 °C, and 88 breaths per min, respectively) in HSC vs. TN pigs, regardless of feeding treatment. Gastrointestinal temperature was greater (P = 0.03; 0.97 °C) in HSC + AF vs. HSC + NF pigs from 45 to 180 min of the recovery period. During the recovery period, feeding attempts were greater (P = 0.02; 195.38%) in AF vs. NF pigs. No drinking attempt differences were detected with any comparison (P > 0.05). A decrease (P < 0.01) in jejunum and ileum villus height (24.72% and 26.11%, respectively) and villus height-to-crypt depth ratio (24.03% and 25.29%, respectively) was observed in HSC vs. TN pigs, regardless of feeding treatment. Ileum goblet cells were reduced (P = 0.01; 37.87%) in HSC vs. TN pigs, regardless of feeding treatment. In summary, TGI decreased more rapidly following acute hyperthermia when the feed was removed, and this may have implications toward using feed removal as a strategy to promote acute hyperthermia recovery in pigs.

In utero heat stress alters postnatal phenotypes in swine

The prenatal environment influences offspring health and development, and this is readily apparent when considering the well-described effects of maternal nutrition and stress on the postnatal metabolism, neural function, and stress response of progeny. Moreover, in laboratory species, sheep, and humans, the effects of in utero heat stress on offspring development have been described in detail for >50 years. Despite our extensive knowledge of the postnatal phenotypes elicited by in utero stressors, the carryover effects of in utero heat stress in pigs have only recently begun to be elucidated. The effects of climate change on increasing global temperatures, combined with greater metabolic heat production in modern swine, has increased heat stress susceptibility in pigs. Greater heat stress susceptibility can negatively affect swine welfare and performance and may impact future generations of pigs through in utero heat stress. Pigs exposed to in utero heat stress develop a variety of postnatal phenotypes that prevent profitable production, and compromise health, and welfare in commercial production systems. Specifically, in utero heat stress alters the postnatal stress response, core body temperature, response to an immune challenge, and is teratogenic. In addition, in utero heat stress changes postnatal body composition through reduced lean and increased adipose tissue accretion rates, respectively. Furthermore, in utero heat stress reduces piglet birth weight, body weight gain, and reproductive efficiency. Although the economic impact of in utero heat stress in pigs has yet to be determined, it likely rivals the postnatal consequences of heat stress and is a threat to the global sustainability of swine production.

Genetic Selection for Thermotolerance in Ruminants

Variations in climatic variables (temperature, humidity and solar radiation) negatively impact livestock growth, reproduction, and production. Heat stress, for instance, is a source of huge financial loss to livestock production globally. There have been significant advances in physical modifications of animal environment and nutritional interventions as tools of heat stress mitigation. Unfortunately, these are short-term solutions and may be unsustainable, costly, and not applicable to all production systems. Accordingly, there is a need for innovative, practical, and sustainable approaches to overcome the challenges posed by global warming and climate change-induced heat stress. This review highlights attempts to genetically select and breed ruminants for thermotolerance and thereby sustain production in the face of changing climates. One effective way is to incorporate sustainable heat abatement strategies in ruminant production. Improved knowledge of the physiology of ruminant acclimation to harsh environments, the opportunities and tools available for selecting and breeding thermotolerant ruminants, and the matching of animals to appropriate environments should help to minimise the effect of heat stress on sustainable animal genetic resource growth, production, and reproduction to ensure protein food security.

Intergenerational Transmission of Characters Through Genetics, Epigenetics, Microbiota, and Learning in Livestock

Evolutionary biologists studying wild species have demonstrated that genetic and non-genetic sources of information are inherited across generations and are therefore responsible for phenotypic resemblance between relatives. Although it has been postulated that non-genetic sources of inheritance are important in natural selection, they are not taken into account for livestock selection that is based on genetic inheritance only. According to the natural selection theory, the contribution of non-genetic inheritance may be significant for the transmission of characters. If this theory is confirmed in livestock, not considering non-genetic means of transmission in selection schemes might prevent achieving maximum progress in the livestock populations being selected. The present discussion paper reviews the different mechanisms of genetic and non-genetic inheritance reported in the literature as occurring in livestock species. Non-genetic sources of inheritance comprise information transmitted via physical means, such as epigenetic and microbiota inheritance, and those transmitted via learning mechanisms: behavioral, cultural and ecological inheritance. In the first part of this paper we review the evidence that suggests that both genetic and non-genetic information contribute to inheritance in livestock (i.e. transmitted from one generation to the next and causing phenotypic differences between individuals) and discuss how the environment may influence non-genetic inherited factors. Then, in a second step, we consider methods for favoring the transmission of non-genetic inherited factors by estimating and selecting animals on their extended transmissible value and/or introducing favorable non-genetic factors via the animals’ environment.

PHYSIOLOGY SYMPOSIUM: Postnatal consequences of in utero heat stress in pigs

Postnatal heat stress negatively impacts pig productivity and well-being as animals attempt to manage the resultant strain response. This is especially true when postnatal heat stress is combined with production stressors (e.g., mixing, weaning, transport, handling, and isolation) that have the potential to increase disease occurrence, morbidity and mortality. While pigs can utilize adaptive physiological mechanisms to compensate, these are often unfavorable to efficient livestock production. Specifically, postnatal heat stress decreases weight gain, reduces growth and production efficiency, alters carcass composition, and increases morbidity and mortality. Consequently, decreased animal performance constrains profitability and affects economic sustainability. In addition to the negative effects of postnatal heat stress, prenatal heat stress has long-term consequences that may compromise future piglet well-being and performance. Pigs gestated under heat stress conditions have an increased postnatal stress response and an increase in maintenance energy requirements. Furthermore, prenatal heat stress decreases swine birth weight, and increases teratogenicity, core body temperature set-point, and alters postnatal body composition (more adipose tissue and less skeletal muscle). Taken together, the effects of heat stress during pre- and postnatal pig development negatively influences productivity and well-being, a scenario that threatens the sustainability of global swine production.

Effects of pen location on thermoregulation and growth performance in grow-finish pigs during late summer

The effects of pen location on swine thermoregulation and growth performance were determined over 6 weeks during late summer. A total of 128 mixed sex pigs [Duroc × (Landrace × Yorkshire)] were randomly assigned to 16 pens in two grow-finish barns (n = 8 pens/barn; 57.43 ± 1.33 kg initial body weight (BW)). Pen locations were determined based on orientation to ventilation fans and air inlets. Internal pens (IP; n = 4/barn) were in direct line of sight between the fans and air inlets while peripheral pens (PP; n = 4/barn) were located 0.70 ± 0.29 m to either side of a fan. Two sentinel gilts per pen were selected and vaginal temperature (T_V) was measured in 10-min intervals using T_V data loggers. Additionally, trunk skin temperature (T_S) was measured with an infrared camera and respiration rate (RR) was measured by counting flank movements of the sentinel gilts twice daily (0800 and 1500 hours). Pen airspeed was measured twice daily (0800 and 1500 hours) at pig level with an anemometer. Individual pen ambient temperature (T_A) and relative humidity (RH) were recorded daily in 10-min intervals. Feed consumption and BW were determined every 2 weeks. Data were analyzed using PROC MIXED in SAS 9.4. Although airspeed was reduced overall (P = 0.01; 11%) in PP compared with IP, no differences (P > 0.10) in T_A (27.53 ± 1.73 °C) or RH (68.47 ± 5.92%) were detected. An overall increase (P ≤ 0.02) in T_V (0.23 °C)_, minimum T_V (0.18 °C), and maximum T_V (0.29 °C) was detected in PP versus IP housed pigs. Similarly, from 0800 to 1900 hours and 2000 to 0700 hours, T_V was greater overall (P ≤ 0.01; 0.22 and 0.25 °C, respectively) in PP compared with IP housed pigs. An overall decrease in T_S (P = 0.04) was observed in PP (37.39 ± 0.14 °C) compared with IP (37.61 ± 0.14 °C) housed pigs. No RR differences (P > 0.10; 76 ± 4 breaths per minute) were detected with any comparison. While no average daily gain (ADG) and average daily feed intake (ADFI) differences were detected (P > 0.10; 0.74 ± 0.03 kg/d and 2.26 ± 0.08 kg/d, respectively), gain-to-feed ratio (G:F) was decreased (P = 0.02; 6%) in PP compared with IP housed pigs. In summary, pigs located in PP had greater body temperature and reduced G:F despite similarities in T_A and RH between all pens.

Effect of Floor Cooling on Behavior and Heart Rate of Late Lactation Sows Under Acute Heat Stress

Much U.S. swine production is in Köppen climate types classified as "hot-summer humid continental" and "humid subtropical." As a result, farrowing sows are often exposed to temperatures above their upper critical temperature. This heat stress (HS) can affect sow welfare and productivity and have a negative economic impact. The study objective was to evaluate the impact of a cooling pad on sows' behavioral and heart rate responses to acute HS. Treatments were randomly allotted to ten multiparous sows to receive a constant cool water flow of 0.00 (CONTROL, n = 4), 0.25 (LOW, n = 2), 0.55 (MEDIUM, n = 2), or 0.85 (HIGH, n = 2) L/min for 100 min and replicated eight times, switching treatments so that each sow was exposed to each treatment. The cooling was initiated 1 h after the room reached 35°C for 100 min. Eating, drinking and nursing behaviors, postures, and heart rate were recorded before heating (Period 1), prior to cooling (Period 2), and during cooling (Period 3). There were no differences between LOW, MEDIUM, and HIGH flow rates for any periods on all behavioral and heart rate traits, so data were pooled (COOLED). There were no differences in any of the measures during Periods 1 and 2, except for the ratio of short term to long term heart rate variability (SD1:SD2) with higher values for CONTROL than COOLED sows in Period 2. During Period 3, CONTROL sows changed postures more frequently (11.5 ±1.6 vs. 5.1 ±1.6 changes per hour), spent more time drinker-pressing/drinking (4.4 ± 0.5 vs. 1.4 ± 0.4% of time), standing (6.6 ± 1.7 vs. 3.8 ± 1.6% of time), sitting (10.0 ± 1.2 vs. 4.0 ± 1.1), less time lying (83.0 ±1.8 vs. 92.0 ±1.7% of time), especially lying laterally (62.0 ± 5.6 vs. 75.0 ± 5.3% of time), than sows in all three cooling treatments (all P < 0.001). Heart rate during Period 3 was lower for COOLED sows compared to the CONTROL sows (100.2 ± 3.4 vs. 119.0 ± 4.0 beat per min, P < 0.001). Sows response to increased thermal load can be effectively reduced using water-cooled cooling pads, thereby improving sow comfort and welfare. The beneficial effects on behavior are noticeable from the lowest flow rate.