Las temperaturas elevadas registradas durante la época de verano en las regiones cálidas comprometen la capacidad reproductiva de los animales domésticos. En carneros, el estrés por calor (EC) causa en el organismo una serie de ajustes fisiológicos, metabólicos, endocrinos y moleculares con el objeto de mantener normotermia y sobrevivir; sin embargo, varios de estos cambios se asocian negativamente con su fertilidad, principalmente los endocrinos. El EC en carneros provoca una disminución en las concentraciones sanguíneas de testosterona a través de diferentes mecanismos, y esto se refleja negativamente en el proceso de espermatogénesis y en la conducta sexual. En consecuencia, los carneros estresados por calor presentan baja calidad seminal y apetito sexual; a nivel de espermatozoides se ha observado daño estructural y en el ADN. Dada esta situación, se recomienda el uso de estrategias de mitigación del EC durante el verano en las explotaciones ovinas de regiones cálidas, tales como el uso de sombras en corrales, la administración de antioxidantes o modificaciones en la alimentación. Por lo tanto, el objetivo de este documento es revisar el conocimiento actual en relación al efecto del EC sobre la capacidad de termorregulación y reproductiva de los carneros, así como la aplicación de estrategias para su mitigación.

In tropical regions of Mexico, breed horses introduced from European countries are used for recreational activities under hot and humid conditions without considering their well-being. In order to evaluate the effect of winter conditions on physiological responses of two equine breeds, twelve horses (six Spanish and six Friesian breeds) were evaluated in the western Pacific coast of Mexico. The winter season was divided in 3 periods so that the statistical model included the factors breed and period. The physiological responses evaluated were: heart rate (HR), respiratory rate (RR), capillary refill time (CRT), and rectal temperature (RT). The climatic variables ambient temperature (AT) and relative humidity (RH) were used to estimate the temperature-humidity index (THI). Averages for THI, AT and RH were 71.4 units, 24.3 °C, and 53.4%, respectively. The CRT was similar (P > 0.05) among breeds and periods. The interaction B X P was significant (P < 0.05) for HR, RR, and RT in the second and third periods, but not in the first one. As a result, Spanish horses experimented higher (P < 0.05) HR (38.1 vs 37.6 and 38.0 vs 37.0 beats/min), RR (18.8 vs 18.5 and 18.9 vs 17.4 bpm), and RT (38.1 vs 38.0 °C and 38.0 vs 37.8 °C) than Friesian horses during the second and third periods, respectively. Both breeds of horses were exposed to a mild to moderate heat stress during winter tropical conditions; however, Spanish breed horses showed better tolerance to heat stress than Friesian horses based on their physiological measures evaluated.

Formaldehyde has been used in commercial hatcheries to cleanse eggs and prevent illness. However, formaldehyde’s health risks and customer demand for eco-friendly products have spurred interest in natural egg disinfection. Formaldehyde-free natural materials sterilize viable eggs in commercial hatcheries. Formaldehyde’s health and environmental dangers start the chapter. Modern hatcheries need safer and greener options. Natural egg disinfectants are next: plant-based extracts, oils, and acids. These natural chemicals’ mechanisms, bactericidal properties, potential commercial hatchery pros, and cons are evaluated. The chapter also examines commercial hatcheries’ natural disinfectant limits. Cost-effectiveness, efficacy against common diseases, application simplicity, and hatchery equipment compatibility are discussed. Regulations and uniform egg disinfection using natural agents are covered in the chapter. It emphasizes industry stakeholders, researchers, and regulators working together to promote natural alternatives. Finally, formaldehyde-free natural substances can disinfect viable eggs in industrial hatcheries. Studying natural product-based disinfection methods will increase their efficacy, safety, and feasibility. This book chapter concludes with natural alternatives to formaldehyde for cleaning viable eggs in industrial hatcheries.