RESUMEN Antecedentes: Las condiciones climáticas en los países tropicales, ejercen un efecto significativo, sobre la producción de leche. Objetivo: Analizar las condiciones climáticas en la Empresa Pecuaria Genética Los Naranjos y su posible relación con el comportamiento de la producción de leche a 305 días. Materiales y métodos: Se dispuso de una base de datos de 12 625 registros de producción de leche, de vacas que tuvieron sus partos entre los años 2002 -2020 que se correspondieron con 7 711 animales. Se contó con los registros mensuales de la temperatura mínima (Tmin), media (Tmed) y máxima (Tmáx) en 0C, humedad relativa (HR) en % y se generó el índice temperatura-humedad (ITH), y a partir de este se realizó el cálculo de la Carga Calórica Acumulada (CCA) de los tres meses antes del parto. Además, se estimaron las heredabilidades (h2) y las correlaciones genéticas (rg) para las diferentes CCA. Resultados: Las medias generales obtenidas fueron: PL305: 1 624,45 ± 360.40 (kg/lactancia), ITH 76,34± 18,70 y CCA 229,21± 128,5. Todas las fuentes de variación estudiadas influyeron en forma significativa en la producción de leche a 305 días. Las h2 variaron entre 0,25 y 0,38 y las rg fueron todas positivas y más altas para los grupos de CCA más próximos. Conclusiones: Hubo relación inversa entre el ITH y la CCA con la producción de leche. Se evidencia la variabilidad genética aditiva para los diferentes grupos de CCA y las rg fueron positivas denotando cierta variabilidad genética para la adaptación al stress climático.

ABSTRACT Background: Climatic conditions in tropical countries have a significant effect on milk production. Aim: Analyze the climatic conditions at the Los Naranjos Genetic Livestock Company and its possible relationship with the behavior of milk production at 305 days. Materials and methods: A database of 12,625 milk production records was available, from cows that gave birth between the years 2002 -2020, which corresponded to 7,711 animals. There were monthly records of the minimum temperature (Tmin), average (Tmed) and maximum (Tmax) at 0C, relative humidity (RH) in % and the temperature-humidity index (ITH) was generated, and from this the performed the calculation of the Accumulated Caloric Load (CCA) for the three months before delivery. In addition, heritabilities (h2) and genetic correlations (rg) were estimated for the different CCAs. Results: The general means obtained were: PL305: 1 624.45 ± 360.40 (kg/lactation), ITH 76.34 ± 18.70 and CCA 229.21 ± 128.5. All sources of variation studied significantly influenced milk production at 305 days. The h2 ranged between 0.25 and 0.38 and the rgs were all positive and higher for the closer CCA groups. Conclusions: There was an inverse relationship between ITH and CCA with milk production. Additive genetic variability is evident for the different CCA groups and the rg were positive denoting certain genetic variability for adaptation to climatic stress.

ABSTRACT The goal of this investigation was to study the influence of different values of Temperature-Humidity index (THI) on the duration of lying down and feed consumption, productivity, and heat production by dairy cows in two variants of feedlots (with and without shelters). The study was conducted from February 2007 to early August 2021 in the central part of Ukraine (Kyiv region) in different periods of THI. This index was divided into three categories: 1) 66-71: normal (14 days); 2) 72-79: alert (11 days); 3) ≥ 80: dangerous (9 days). Two variants of feedlots were selected: Open feedlot with shelters and open feedlot without shelters. The largest increase in values of THI affecting the cows was observed in open feedlots without shelters. There, in alert and danger periods duration of feed consumption decreased by 8.0 and 23.1 min, lying down by 17 and 38 min, productivity by 2.3 kg (or 8.77%) and 3.6 kg (or 13.74%), energy consumption by 4.7 and 9.6 MJ, respectively, in comparison to normal period.

RESUMEN El objetivo del estudio fue evaluar la influencia de diferentes valores de Índice temperatura-humedad (IHT) sobre el tiempo de reposo y el consumo de alimento, la productividad y la producción de calor de las vacas lecheras en dos variantes de feedlots (con y sin refugio). El estudio se llevó a cabo desde febrero de 2007 hasta principios de agosto de 2021 en la parte central de Ucrania (región de Kiev) en diferentes períodos de IHT. El índice se dividió en tres categorías: 1) 66-71: normal (14 días); 2) 72-79: alerta (11 días); 3) >80: peligroso (9 días). Se seleccionaron dos variantes de feedlots: abierto con sombra y abierto sin sombra. El mayor aumento en los valores de IHT que afectaron a las vacas se observó en los corrales de engorda abiertos sin sombras. Allí, en periodos de alerta y peligro, la duración del consumo de alimento disminuyó en 8.0 y 23.1 min, acostado en 17 y 38 min, la productividad en 2.3 kg (o 8.77%) y 3.6 kg (o 13.74%), el consumo de energía en 4.7 y 9.6 MJ, respectivamente, en comparación con el periodo normal.

ABSTRACT Climate change continues to influence global ecosystems, raising concerns for livestock. This study assesses the impacts of climate change on broiler chickens in northern Tunisia, focusing on well-being and mortality rates during summer. Historical data from the NRMCM5.1 and MPIESM1.2 models, were utilized, covering 1970 to 1997. Projections for 2041-2070 under the RCP4.5 and RCP8.5 emissions scenarios were examined, providing insight into future challenges. The Temperature-Humidity Index (THI) and Temperature-Humidity-Velocity Index (THVI) served as thermal comfort indicators. The research utilized temperature and relative air humidity data from two models and scenarios (RCP4.5 and RCP8.5) as inputs for the DCP system, thus evaluating comfort parameters (THI and THVI). The analysis involved calculating annual temperature and humidity averages at the system’s output for each grid and region. Historical and projected data were employed to assess mortality levels by identifying heatwave periods, which had an average duration of 2.7 consecutive days with THI exceeding 30.6°C. The analysis showed significant increases in THI and THVI in the RCP8.5 pessimistic scenario, indicating a risk of heat stress. Mortality rates were used as a measure of the vulnerability of the poultry industry to climate change, and the projections showed substantial average increases of 2.2°C for THI and 1.5°C for THVI.. The RCP4.5 and RCP8.5 scenarios predicted an increase in mortality for the period 2041-2070, with averages increasing from 0.8 to 1.3 for RCP8.5 and from 0.6 to 1.1 for RCP4.5, highlighting the need for adaptation strategies to ensure sustainability in poultry farming. ecosystems livestock Tunisia wellbeing well being summer NRMCM51 NRMCM NRMCM5 1 NRMCM5. MPIESM12 MPIESM MPIESM1 2 MPIESM1. 197 1997 20412070 2041 2070 2041-207 RCP45 RCP RCP4 5 RCP4. RCP85 RCP8 RCP8. examined challenges TemperatureHumidity Temperature Humidity TemperatureHumidityVelocity Velocity (THVI indicators (RCP4. system THVI. . THVI) systems s region periods 27 7 2. 306C C 30 6 30.6°C scenario stress 22C 15C 20412070, 2070, 08 0 8 0. 13 3 1. 06 11 farming 19 199 2041207 204 207 2041-20 (RCP4 204120 20 2041-2 (RCP 20412 2041-

ABSTRACT. Sidewall openings play an important role in the indoor conditions of livestock buildings. It influences airflow patterns, air velocity distribution at the animal-occupied zones and the illumination level in the naturally ventilated animal building. However, there is a paucity of information on the effects of sidewall opening areas on the performance of broiler chickens. Hence, this study investigated the effect of sidewall opening areas on the indoor condition and the body growth of broilers. Two buildings with different sidewall opening areas were developed with broiler chickens reared in them for 28 days. The results showed that air temperatures and relative humidity of the buildings were influenced by the outdoor temperature. The indoor air temperatures of the building exceeded the recommended thermal conditions (18 to 24ºC) for broiler chickens. Similarly, the temperature-humidity index of the building exceeded 21.0ºC recommended for broilers which could result in heat stress and poor performance of broiler chickens during extremely hot weather periods. It was also found in this study that broiler chickens could not perform optimally though they were fed ad libitum. Therefore, further studies are required to ascertain the impact of sidewall opening areas on broiler performance, behaviour and physiological responses. ABSTRACT patterns animaloccupied occupied However Hence 2 days temperature 18 (1 24ºC ºC Similarly temperaturehumidity 210ºC 21 0ºC periods libitum Therefore responses 1 (

The objective of this study was to investigate the effect of seasonal thermal stress on serum hormones, oxidative status, and immune response of periparturient dairy cows. A total of 32 healthy Holstein dairy cows in the perinatal period with the same date of delivery were selected (eight cows per season) and housed in a free-stall barn. Different seasons corresponded to different temperature-humidity indices (THI). Regression analysis revealed a strong positive correlation between THI and rectal temperature and respiratory rate. On the day of calving, the level of progesterone and oestradiol increased and prolactin decreased substantially at a high THI. For oxidative stress biomarkers, the contents of malondialdehyde, superoxide dismutase, and catalase were substantially higher at a low THI. Glutathione peroxidase was increased at a high THI. For immune responses, the data indicated that low and high THI conditions led to an increase in interleukin-2 and interleukin-10. Low THI cows exhibited a substantially higher level of tumour necrosis factor-a before calving. Oxidative stress, inflammatory response, and endocrine imbalance therefore occur in lactating dairy cows in hot summers and cold-wet winters in comparison with comfortable seasons.

ABSTRACT The objective of this research was to determine the influence of heat stress, using the temperature-humidity index (THI), on the production and quality of native sperm of bulls. The effect of heat stress on the quantity of semen (mL), density of ejaculate (number of spermatozoa, 106/mL), gross sperm motility (1-5), number of frozen doses, and motility after freezing was analysed in 1,017 sperm samples taken from 32 Holstein-Friesian bulls, in the 2017-2019 period, at the Centre for Reproduction and Embryo Transfer in Serbia. The lowest amount of ejaculate (4.18±1.95 mL) and the lowest density of ejaculate (1,189.19±668.23 × 106/mL) were recorded under conditions of very strong heat stress on the day of semen collection. The level of heat stress measured on the day of semen collection did not affect sperm gross motility, number of frozen doses, and motility after freezing. The level of heat stress at the beginning of spermatogenesis, measured 60 days before semen collection, did not affect the amount of ejaculate and motility of spermatozoa after freezing, but at very strong stress, the lowest density of ejaculate (1,170.34±680.27 × 106/mL) and gross motility of spermatozoa were found (2.91±0.96). The lowest number of doses per ejaculate was recorded in conditions of moderate heat stress (396.6±157.71). Bulls older than 36 months had the best results according to all tested parameters of native sperm production and quality. The year in which the bulls produced semen did not affect density of ejaculate and sperm motility. The season of semen collection did not significantly affect the production and quality of native sperm, due to the practice of exploiting only bulls with the best sperm quality during the summer. temperaturehumidity temperature humidity THI, THI , (THI) mL, mL (mL) 106/mL, 106mL 106/mL 106 15, 15 1 5 (1-5) 1017 017 1,01 3 HolsteinFriesian Holstein Friesian 20172019 2017 2019 2017-201 period Serbia 4.18±1.95 418195 4 18 95 (4.18±1.9 1,189.19±668.23 11891966823 189 19 668 23 (1,189.19±668.2 spermatogenesis 6 1,170.34±680.27 11703468027 170 34 680 27 (1,170.34±680.2 2.91±0.96. 291096 2.91±0.96 . 2 91 0 96 (2.91±0.96) 396.6±157.71. 396615771 396.6±157.71 396 157 71 (396.6±157.71) summer (THI (mL 10 (1-5 101 01 1,0 2017201 201 2017-20 4.18±1.9 41819 9 (4.18±1. 1,189.19±668.2 1189196682 66 (1,189.19±668. 1,170.34±680.2 1170346802 17 68 (1,170.34±680. 29109 2.91±0.9 (2.91±0.96 39661577 396.6±157.7 39 7 (396.6±157.71 (1- 1, 201720 20 2017-2 4.18±1. 4181 (4.18±1 1,189.19±668. 118919668 (1,189.19±668 1,170.34±680. 117034680 (1,170.34±680 2910 2.91±0. (2.91±0.9 3966157 396.6±157. (396.6±157.7 (1 20172 2017- 4.18±1 418 (4.18± 1,189.19±668 11891966 (1,189.19±66 1,170.34±680 11703468 (1,170.34±68 291 2.91±0 (2.91±0. 396615 396.6±157 (396.6±157. ( 4.18± 41 (4.18 1,189.19±66 1189196 (1,189.19±6 1,170.34±68 1170346 (1,170.34±6 29 2.91± (2.91±0 39661 396.6±15 (396.6±157 4.18 (4.1 1,189.19±6 118919 (1,189.19± 1,170.34±6 117034 (1,170.34± 2.91 (2.91± 3966 396.6±1 (396.6±15 4.1 (4. 1,189.19± 11891 (1,189.19 1,170.34± 11703 (1,170.34 2.9 (2.91 396.6± (396.6±1 4. (4 1,189.19 1189 (1,189.1 1,170.34 1170 (1,170.3 2. (2.9 396.6 (396.6± 1,189.1 118 (1,189. 1,170.3 117 (1,170. (2. 396. (396.6 1,189. 11 (1,189 1,170. (1,170 (2 (396. 1,189 (1,18 1,170 (1,17 (396 1,18 (1,1 1,17 (39 1,1 (1, (3

ABSTRACT The objective of this study was to evaluate the effect of milking hygiene practices, herd size, water hardness, and temperature-humidity index (THI) on the physicochemical and microbiological characteristics of raw milk, and standard plate count (SPC) in milking machines of dairy farms in the central region of Mexico. Data were collected from fifty-three dairy farms during one year. The evaluated effects included milking hygiene conditions (good, medium, poor), herd size (1-50, 51-100, 101-150, ≥151 heads), water hardness (soft or moderately hard), and THI (comfortable or stressful). The increase in milking hygiene produced greater milk yield (MY) and energy corrected milk (ECM) but lower protein content, and decreased the individual bacterial count (IBC) and somatic cell count (SCC). The MY, ECM, protein content, IBC, and SCC were higher on bigger farms. The use of soft water reduced MY, IBC, and SCC, but improved fat, lactose, total solids (TS), and non-fat solids (NFS). Heat stress negatively affected fat, protein, TS, NFS, acidity, freezing point (FP), SCC, and methylene blue dye reduction test. Poor milking hygiene contributes to higher SPC in milking machine parts. Water hardness and THI did not affect SPC in all milking machine parts. Proper milking hygiene practices, larger herd size, softer water, lower THI, and adequate cleaning and disinfection of the milking machine parts benefits the physicochemical and microbiological quality of the milk. practices temperaturehumidity temperature humidity (THI (SPC Mexico fiftythree fifty three year good, good (good medium poor, poor , poor) 150, 150 1 50, 50 (1-50 51100, 51100 51 100, 100 51-100 101150, 101150 101 101-150 151 ≥15 heads, heads heads) hard, hard hard) comfortable stressful. stressful . stressful) MY (MY ECM (ECM content IBC (IBC SCC. (SCC) fat lactose TS (TS) nonfat non NFS. NFS (NFS) acidity FP, FP (FP) test 15 5 (1-5 5110 10 51-10 10115 101-15 ≥1 (SCC (TS (NFS (FP (1- 511 51-1 1011 101-1 ≥ (1 51- 101- (

ABSTRACT The present study investigated whether the same temperature-humidity index (THI) values under different conditions of air temperature and relative humidity (RH) would affect the thermoregulatory, nutritional, and behavioral responses of laying hens. One hundred twenty Hy-Line Brown laying hens (60-weeks-old) were divided equally in two environmental chambers: 26 °C with 70% RH (hRH75) and 30 °C with 30% RH (hT75) for 28 days. The two ambient environments (hRH75 and hT75) had an identical THI value of 75, calculated using an empirical formula for laying hens. Neither hRH75 nor hT75 affected rectal and body-surface temperatures and heart and respiratory rates. The concentration of volatile fatty acids in fecal excreta were altered by the thermal treatments. hT75 vs. hRH75 decreased the proportion of acetate and increased the proportion of propionate in fecal samples. hT75 vs. hRH75 lowered the digestibility of dry matter, crude protein, and neutral detergent fiber at 14 days. Thermal treatments did not affect heat stress-associated behavioral responses including feeding, drinking, panting, and wing elevation at any stage. Laying hens exposed to the same THI at different temperatures and RH exhibit equal physiological responses including rectal and body-surface temperatures, heart and respiratory rates, and behavioral responses. Nonetheless, high-temperature treatment (hT75; 30 °C and 30% RH) vs. low temperature treatment (hRH75; 26 °C and 70% RH) affects nutrient digestibility and gut metabolites, suggesting that there are negligible but discernable responses to temperature in the gut physiology. temperaturehumidity (THI (RH thermoregulatory nutritional HyLine Hy Line 60weeksold weeksold 60 weeks old (60-weeks-old chambers 2 C 70 hRH 3 hT (hT75 days (hRH7 75 hRH7 hT7 bodysurface body surface rates vs samples matter protein 1 stressassociated stress associated feeding drinking panting stage Nonetheless hightemperature high metabolites physiology 6 7 (hT7 (hRH (hT

RESUMO: Os suínos são animais que apresentam dificuldade em realizar trocas de calor, por esse motivo é importante considerar os fatores ambientais que impactam seu desempenho produtivo. O objetivo do presente trabalho foi avaliar o efeito do conforto térmico e do fotoperíodo, sobre o desempenho produtivo das porcas na gestação e leitões na maternidade. Os dados zootécnicos foram obtidos de uma granja comercial. O índice de temperatura e umidade (ITU) foi utilizado como parâmetro para o conforto ou o estresse térmico da matriz. Foram analisados os parâmetros das fêmeas no período gestacional e dos leitões na maternidade, considerando os critérios de conforto, estresse e quatro faixas de fotoperíodos. A correlação entre o fotoperíodo e ITU foi alta e positiva, demonstrando efeito associado dessas variáveis. Foram observados mais efeitos significativos em situações de conforto e faixas de menor fotoperíodo. Em conclusão, o conforto térmico e o fotoperíodo influenciaram os parâmetros avaliados na gestação e na maternidade e a alta associação ITU e fotoperíodo sugere que o controle ambiental pode favorecer parâmetros produtivos em granjas comerciais.

ABSTRACT: Pigs have difficulty in performing heat exchange and; therefore, it is important to consider the environmental factors that impact their productive performance. This study evaluated the effect of thermal comfort and photoperiod on the productive performance of sows during pregnancy and of nursery piglets. Zootechnical data were obtained from a commercial farm. The temperature-humidity index (THI) was used as the parameter to determine comfort or thermal stress of the sow. The parameters of the sows during pregnancy and nursery piglets were analyzed considering the criteria of comfort, stress, and four photoperiods. The correlation between photoperiod and THI was high and positive, which demonstrated the associated effect of these variables. More significant effects were observed under conditions of comfort and shorter photoperiods. In conclusion, thermal comfort and photoperiod influenced the parameters evaluated during pregnancy and in the nursery, and the strong association between THI and photoperiod suggested that environmental control favors productive parameters in commercial farms.

RESUMO Objetivou-se avaliar as condições térmicas a que os animais estão submetidos, seu efeito no conforto/desconforto de rebanhos leiteiros em sistema de pastejo, no município de Sena Madureira-Acre. Foram avaliadas oito propriedades e o total de 113 vacas mestiças em lactação. As medições ocorreram nos meses: janeiro, fevereiro e março (inverno amazônico), mensurando-se: temperatura do bulbo seco (TBS, °C), umidade relativa do ar (UR, %) e temperatura de globo negro (TGN, °C), velocidade do vento (v, km/h) para cálculos dos índice da temperatura e umidade (ITU), índice da temperatura de globo e umidade (ITGU) e carga térmica radiante (CTR), além da temperatura retal (TR), frequência cardíaca (FC), frequência respiratória (FR). Entre as propriedades analisadas, houve diferenças significativas (P<0,05) para ITU, ITGU e CTR. Destaca-se que o ITU na propriedade G, em janeiro, atingiu o valor médio de 80. A propriedade F, em fevereiro, teve valor de 79 para o ITGU. A CTR apresentou carga elevada (510 W.m-²). A TR e a FC não apresentaram diferença entre os meses analisados. Concluiu-se que o ambiente ao qual as vacas leiteiras estão alojadas na hora da ordenha encontraram-se poucas vezes em situação de desconforto térmico, sendo a propriedade , a mais afetada pelo ITU.

ABSTRACT This study aimed to evaluate the thermal conditions to which animals are exposed and their effect on the comfort/discomfort of dairy herds in a grazing system in the municipality of Sena Madureira, Acre State, Brazil. Eight farms and a total of 113 lactating crossbred cows were evaluated. Dry-bulb temperature (DBT, °C), relative humidity (RH, %), black globe temperature (BGT, °C), and wind speed (v, km h−1) were measured in January, February, and March (rainy season) to calculate temperature-humidity index (THI), black globe-humidity index (GTWBI), and radiant heat load (RHL). Moreover, the animals were measured for the physiological variables: rectal temperature (RT), heart rate (HR), and respiratory rate (RR). Significant differences (P<0.05) were observed for THI, GTWBI, and RHL. THI reached a mean value of 80 on farm G in January. Farm F had a GTWBI value of 79 in February. RHL reached the highest value (510 W m−2). RT and HR showed no differences among the analyzed months. Thus, the environmental conditions in which dairy cows are housed at milking time rarely promoted thermal discomfort, with farm G being the most affected by THI.

RESUMEN Se determinó la respuesta fisiológica y su relación con el índice de impacto (estrés) calórico en tres razas de bovinos criollos colombianos (Hartón del Valle, Blanco Orejinegro y Sanmartinero). Dichas razas son consideradas adaptadas a las condiciones de trópico bajo e importantes para la producción de carne y leche en Colombia. El objetivo del estudio fue determinar dos índices de tolerancia al calor y dos hormonas y su relación con la respuesta fisiológica al estrés calórico en tres razas criollas colombianas usando análisis de correlación y comparación de medias. Los índices de adaptabilidad ITH y HLI, las hormonas cortisol y T3 se estimaron y estos se correlacionaron con las hormonas y se compararon las medias. Se analizaron las variables fisiológicas: frecuencia cardíaca, respiratoria y ruminal y, temperatura rectal; igualmente se determinaron las concentraciones séricas de las hormonas cortisol y triyodotironina, en siete momentos en la época de lluvias en el Piedemonte Llanero. El índice de temperatura y humedad (ITH) y el índice de carga calórica (HLI) fueron empleados como indicadores de compensación térmica. El HLI mostró mejor relación con las condiciones ambientales al incluir el índice la velocidad del viento y la radiación solar. No se encontraron variaciones entre los grupos raciales (P≥0,05), mientras que los periodos de medición sí presentaron variaciones (P≤0,05). Se concluye que el HLI proporciona mejor información para el estudio de los parámetros fisiológicos y éstos reflejan la adaptación de los animales a las condiciones del medio.

ABSTRACT The present study aimed to determine the physiological response and its relationship with the caloric impact (stress) index of three breeds of Colombian Creole cattle (Hartón del Valle, Blanco Orejinegro y Sanmartinero). These breeds have been considered adapted to low-tropical conditions and important to the sustainable meat and milk production in Colombia. To determine two heat tolerance indexes and two hormones and their relationship to the physiological response to heat stress in three Colombian Creole cattle breeds, Pearson's correlation methodology and mean comparison study were used. The adaptability indexes such as temperature-humidity index (ITH) and heat load index (HLI) and cortisol and T3 hormones were estimated and subsequently, the indexes were correlated with the hormones using the Pearson methodology, also the mean comparison study was used. Physiological variables were analyzed such as heart rate, respiratory rate, rumen patterns, and rectal temperature; during the study, serum concentrations of cortisol and triiodothyronine hormones were detected in seven different instances during the rainy season in the Piedemonte Llanero. ITH and HLI were used as indicators of thermal compensation. The HLI appeared to be a better indicator when the environmental conditions included wind speed and solar radiation. No variations were found between the breeds (P≥0.05), while the measurement periods did show variations (P≤0.05). It may conclude that the HLI provides better information to study physiological parameters and it may confirm that the animals are considered adapted to the conditions of the local environment.

Resumen En este estudio se analizó la relación de la temperatura (T), humedad relativa (HR) e índice de temperatura-humedad (ITH) sobre la mortalidad y el peso corporal de cuyes (Cavia porcellus) de la línea sintética en la ciudad de Moquegua, Perú. Para ello, se evaluaron 157 cuyes entre octubre del 2019 y marzo del 2020, a través del análisis de la variabilidad y los niveles de asociación entre T, HR, ITH, mortalidad y peso. Los datos fueron procesados en STATA IC14. Los resultados de T, HR e ITH registrados mensualmente mostraron cambios altamente significativos (p < 0,001), al igual que el peso entre machos y hembras (p < 0,05). Los coeficientes de correlación estadísticamente significativos se hallaron entre el peso de cuyes machos y T a la semana 4 (r = -0,345) y a la 6 (r = -0,352); HR, a la semana 4 (r = -0,388) y a la 6 (r = -0,387); e ITH, a la semana 4 (r = -0,387) y a la 6 (r = -0,374). No se demostró correlación entre la mortalidad e ITH (p > 0,05); además, se observó un incremento en la mortalidad en situación de estrés (ITH > 72). El incremento de peso de cuyes machos mostró tendencia lineal a ITH ≤ 72 (r2 = 0,993) e ITH > 72 (r2 = 0,994). De igual manera, el incremento de peso de las hembras mostró tendencia lineal a ITH ≤ 72 (r2 = 0,996) e ITH > 72 (r2 = 0,997).

Abstract This study analyzed the relationship of temperature (T), relative humidity (RH) and temperaturehumidity index (THI) on mortality and the body weight of guinea pigs (Cavia porcellus) of the synthetic line, 157 guinea pigs were evaluated between October 2019 and March 2020. The variability and association level of T, RH and THI, mortality and body weight were analyzed. The data was processed in the STATA IC14. The results of T, RH and THI recorded monthly showed a significant variability (p < 0.001), the same way the body weight between males and females (p < 0.05). Statistically significant correlation coefficients were recorded between weight body male and T at week 4 (r = 0.345) and week 6 (r = - 0.352), RH at week 4 (r = 0.388) and week 6 (r = - 0.387), THI at week 4 (r = - 0.387) and week 6 (r = - 0.374). No correlation was demonstrated between mortality and THI (p > 0.05) we also observed the mortality (%) increase at THI > 72. The body weight in male guinea pigs showed a linear trend at THI ≤ 72 (r2 = 0.993) and THI > 72 (r2 = 0.994) as well as the weight in female guinea pigs THI ≤ 72 (r2 = 0.996) and THI > 72 (r2 = 0.997).

RESUMO Este estudo teve como objetivo avaliar as variáveis ambientais, índices de conforto térmico e respostas fisiológicas de bezerras criadas em bezerreiro do sistema tropical sombreados com geossintéticos. Foram avaliadas 20 fêmeas das raças (Girolando, Jersey e Holandesa) com peso inicial médio de 40.6 kg durante a fase de aleitamento (nascimento até 90 dias de idade). O delineamento experimental foi de blocos casualizados completos, aplicado em um arranjo fatorial 4 × 3, com 5 repetições. Os materiais de cobertura (malha de polietileno, geocomposto drenante, geotêxtil não-tecido e geotêxtil tecido) foram o primeiro fator e os períodos do dia (08 às 10, 12 às 14 e 16 às 18 horas) foram o segundo fator. Foram mensuradas as variáveis ambientais e calculados os índices de conforto térmico: índice de temperatura e umidade, índice de temperatura do globo negro e umidade e entalpia. As variáveis fisiológicas estudadas foram frequência respiratória, temperatura retal e temperatura de superfície corporal. Não houve diferença significativa para as variáveis ambientais e índices de conforto térmico entre as coberturas, entretanto, houve diferença significativa (p ≤ 0.01) entre os períodos do dia, sendo o período mais crítico entre 12 e 14 horas. Os animais mantidos sob a cobertura geocomposto drenante apresentaram as menores médias de frequência respiratória (60.3 mov min-1) e temperatura retal (38.9 °C). Houve diferença significativa (p ≤ 0.05) para a interação entre tratamentos e períodos do dia para a temperatura de canela. Os geossintéticos estudados podem ser utilizados como material de cobertura em bezerreiros, sendo o geocomposto drenante o mais indicado para regiões tropicais.

ABSTRACT This study aimed to assess the environmental variables, thermal comfort indices and physiological responses of calves in outdoor holding pens shaded with geosynthetics. Twenty crossbred females (Giroland, Jersey and Holstein) in the suckling phase (from birth to 90 days old) with an average initial live weight of 40.6 kg were used. A completely randomized block design was used, in a 4 × 3 factorial scheme with five replicates. The roofing materials (polyethylene mesh, geocomposite drainage layer, nonwoven geotextile and woven geotextile) were the first factor and time periods (8 to 10 a.m., 12 to 2 p.m. and 4 to 6 p.m.) the second factor. The following environmental variables were measured to calculate thermal comfort indices: temperature-humidity index, black globe-humidity index and enthalpy. The physiological variables analyzed were respiratory rate, rectal temperature and skin temperature. Environmental variables and thermal comfort indices did not differ between the different roof types, however, a significant difference (p ≤ 0.01) was observed between the time periods, with 12 to 2 p.m. being the most critical period. The lowest average respiratory rate (60.3 breaths min-1) and rectal temperature (38.9 °C) were recorded for the animals kept under the geocomposite drainage layer roof. There was a significant difference (p ≤ 0.05) for interaction between treatment and time periods for the cannon area. The geosynthetics studied can be used as roofing material for outdoor holding pens, with the geocomposite drainage layer being the most indicated for tropical regions.

Resumen Los cruces de razas cebuinas con criollas pueden ser una alternativa para incrementar la eficiencia de la producción de carne. El objetivo de este estudio fue determinar el desempeño productivo de novillos brahman, cruzados con romosinuano y blanco orejinegro. La investigación se desarrolló en finca San Miguel, ubicada en el municipio de Paratebueno (Cundinamarca). Se evaluó un grupo de novillos contemporáneos brahman, brahman x romosinuano y brahman x blanco orejinegro, que permanecieron juntos en potreros de Brachiaria sp. bajo pastoreo continuo durante un año. Se estimó la ganancia de peso, la producción y calidad de forraje, se midió la temperatura, humedad relativa y pluviosidad, y se determinó el índice de temperatura-humedad. Se utilizó un diseño completamente al azar, y se implementó estadística descriptiva y análisis de varianza, para lo cual se utilizó el programa Infostat®. Se presentaron diferencias en la ganancia de peso entre grupos durante el periodo de mayor precipitación (p = 0,013), siendo mayor en brahman x romosinuano, y en el periodo de menor precipitación (p = 0,002), tuvo menor desempeño el cruce brahman x blanco orejinegro. Asimismo, se presentaron diferencias en la producción de forraje (p = 0,0017) y en la calidad nutricional de la pastura, siendo mejor en la época de mayor precipitación. Durante el estudio, el índice de temperatura-humedad estuvo por encima de 82, lo que muestra condiciones de estrés calórico en los animales. Bajo las condiciones agroecológicas de la zona de estudio, el cruce brahman x romosinuano es una alternativa para mejorar los sistemas de producción de carne en el Piedemonte llanero.

Abstract Zebu races crossbred with criollo races can be an alternative to increase the meat production efficiency. This study aims to determine the productive performance of Brahman bullocks crossbred with romosinuano and black-ear white races. The research was developed in the farm San Miguel, located in the town Paratebueno (Cundinamarca). A group of contemporary Brahman, Brahman x romosinuano and Brahman x black-ear white bullocks was evaluated after living together in Brachiaria sp. pastures under continuous herding for one year. The weight gain, production and forage quality were estimated. Temperature, relative humidity and rainfall were also measured and the temperature-humidity index was also determined. A fully random design was used herein including descriptive statistics and analysis of variance. Infostat® software was used to that end. Differences were found in the weight gains between the race groups during the highest rainfall season (p = 0.013); it was higher in the Brahman x romosinuano group. During the lowest rainfall season (p = 0.002) the Brahman x black-ear white group showed a lower performance. Likewise, differences were observed in the forage production (p = 0.0017) and in the nutritional quality of the pastures, with the best forage during highest rainfall season. Throughout this study, the temperature-humidity index was above 82, which indicates that the animals were under caloric stress condition. Under the agricultural-ecological conditions in the study area, the Brahman x romosinuano crossbreeding is an alternative to improve the meat production systems in the Eastern Plains Foothills.

RESUMEN Objetivos. Determinar la existencia de un estrés calórico en pollos de engorda y evaluar la efectividad de la suplementación con un producto orgánico de Cr en la disminución de este. Materiales y Métodos. Se determinó la existencia de un estrés calórico mediante la medición del comportamiento de la temperatura y la humedad relativa durante el experimento. Estos indicadores se registraron diariamente, con frecuencia de una hora, utilizando termohigrómetros digitales. Se utilizaron 45 pollos de engorda Ross 308 sexados machos, desde 1 d de edad, provenientes de un experimento de comportamiento productivo con 300 animales. Estos se distribuyeron en tres tratamientos (control, 200 y 400 ppbCr/ kg de dieta) según un diseño completamente aleatorizado, con 4 repeticiones de 25 pollos cada una. Al finalizar el ciclo productivo se determinó la concentración de cortisol en suero sanguíneo de 15 animales por tratamiento, como indicador de estrés. Cada animal constituyó una unidad experimental. Para el análisis de los resultados, se utilizó el paquete estadístico computarizado INFOSTAT. Resultados. Los valores del índice de confort de temperatura y humedad durante los últimos 32 días de duración de la prueba oscilaron entre 112.53 y 115.26. Las concentraciones promedio de cortisol para los tres tratamientos evaluados fueron de 9.45, 8.91 y 7.66 nmol/L, respectivamente, sin mostrar diferencias significativas entre ellos. Conclusiones. El producto orgánico de Cr fue efectivo en la reducción del estrés calórico al disminuir la concentración de cortisol, aunque no significativamente, en suero sanguíneo de los pollos de engorda. Se ratificó la existencia de un estrés generado por calor durante la realización del experimento.

ABSTRACT Objective. Determinate the existence of a heat stress in broilers and evaluate the effectiveness of the supplementation with an organic Cr product for decreasing or heat stress in broilers. Materials and Methods. The existence of heat stress was determined by measuring temperature and relative humidity during the experiment. These indicators were daily registered, every 1 hour, with the use of digital thermo-hygrometers. An amount of 45 male Ross 308 broilers was used, from 1 day of age, belonging to a productive performance experiment with 300 animals. They were distributed in three treatments (control, 200 and 400 ppbCr/kg of diet) according to a completely randomized design, with 4 repetitions of 25 animals each. At the end of this productive cycle, cortisol concentration in blood serum was determined in 15 animals per treatment, as an indicator of stress. Every animal constituted an experimental unit. For the analysis of results, INFOSTAT statistical package was used. Results. Temperature-humidity index values during the last 32 days of the experiment ranged between 112.53 and 115.26. Mean values of cortisol concentration were 9.45, 8.91 and 7.66 nmol/L, for the three evaluated treatments respectively. This decrease was not statistically significant. Conclusions. The organic Cr product was effective for decreasing heat stress by reducing cortisol concentration, although not significant, in blood serum of broilers. The existence of stress generated by heat during the experiment was confirmed.