Seasonal heat stress compromises testicular thermoregulation and semen quality of Dorper rams raised in a desert climate.

Dorper rams are widely distributed throughout the world under different climatic conditions, however, little is known about their reproductive performance in desert regions. Ten Dorper rams were individually housed and exposed to thermoneutrality for 35 d in spring (23.6 ± 5.6 °C, mean ± SD) and outdoor heat stress (HS) for 35 d in summer (33.6 ± 2.0 °C) to evaluate the effect of seasonal HS on physiological responses, testicular biometry, and seminal quality under desert climatic conditions. Rectal temperature, respiration rate and coat surface temperatures in different body regions were measured every 7 d (0600, 1200, and 1800 h); also, testicular biometry was registered at 0600 h. Semen was collected via an artificial vagina 3 d after physiological variables were measured and seminal traits were evaluated. Rectal temperature, respiration rate and coat surface temperatures were higher (P < 0.01) at each hour of measurement in summer compared to spring. Overall, scrotal length and circumference, as well as testicular volume were higher (P < 0.01) in summer than in spring. Compared to spring conditions, summer HS caused lower (P ≤ 0.05) sperm concentration and viability combined with a higher percentage of sperm abnormalities without affecting ejaculate volume. Both mass and sperm motility were similar between seasons in the first two sampling weeks, and then decreased (P ≤ 0.03) due to summer HS. In conclusion, Dorper rams developed testicle hyperthermia and, consequently, showed poor semen quality due to the high environmental temperatures prevailing in desert regions.

La cabra: selección y hábitos de consumo de plantas nativas en agostadero árido / The goat: selection and intake habits of native plants in arid range

Resumen Las cabras habitan regiones áridas como resultado de su adaptación a condiciones extremas. La selección de la dieta es una de las estrategias conductuales que les han permitido evitar deficiencias nutricionales o intoxicaciones aun en condiciones de baja disponibilidad de alimento. Así mismo, el ramoneo, como conducta ingestiva de la especie, les permite seleccionar y obtener plantas con adecuados valores de proteína cruda que favorezcan su desarrollo y supervivencia. También, las cabras se adaptan a las características químicas de las plantas, las cuales desarrollan compuestos bioactivos para evitar ser consumidas. Estos metabolitos secundarios pueden tener efectos antinutricionales y tóxicos así como medicinales o curativos, dependiendo del consumo que tenga el animal. El objetivo de este trabajo fue revisar la selección y hábitos de las cabras en el consumo de plantas nativas, para determinar cómo favorecen la supervivencia y productividad de la especie, bajo las condiciones de adversidad ambiental que caracterizan a las regiones áridas. Dicho conocimiento permitirá establecer estrategias para el manejo adecuado del agostadero y conocer el efecto que los compuestos del metabolismo secundario de las plantas puedan tener en los procesos reproductivos, nutricionales, sanitarios, así como en los productos derivados de la leche o carne de estos animales.

Abstract Goats dwell arid regions as a result of their adaptation to extreme conditions. Diet selection is one of the behavioral strategies that has allowed them to avoid nutritional deficiencies or poisonings, even under conditions of low food availability. Likewise, browsing as an ingestive behavior of the species allows them to select and obtain plants with adequate crude protein values, which favor their development and survival. Also, goats adapt to the chemical characteristics of plants, which develop bioactive compounds to avoid being consumed. These secondary metabolites can have antinutritional and toxic effects, as well as medicinal or curative effects, depending on the consumption that the animal has. The objective of this work was to review the selection and habits of goats in the consumption of native plants, to determine how they favor the survival and productivity of the species under the conditions of environmental adversity that characterize arid regions. This knowledge will allow to establish strategies for the proper management of the rangeland and to know the effect that the compounds of the secondary metabolism of the plants may have on the reproductive, nutritional, and health processes, as well as on the products derived from the milk or meat of these animals.