Background: At high altitudes, hypoxia, oxidative stress or both compromise sheep fertility. In the present work, we tested the relative effect of short-or long-term exposure to high altitude hypobaric hypoxia and oxidative stress on corpora luteal structure and function. Methods: The growth dynamics of the corpora lutea during the estrous cycle were studied daily by ultrasonography in cycling sheep that were either native or naïve to high-altitude conditions and that were supplemented or not supplemented with antioxidant vitamins. Arterial and venous blood samples were simultaneously drawn for determination of gases and oxidative stress biomarkers and progesterone measurement. On day five after ovulation in the next cycle, the ovaries were removed for immunodetection of luteal HIF-1alpha and VEGF and IGF-I and to detect IGF-II gene expression. Results: The results showed that both short-and long-term exposure to high-altitude conditions decreased luteal growth and IGF-I and IGF-II gene expression but increased HIF-1 alpha and VEGF immunoexpression. The level of plasma progesterone was also increased at a high altitude, although an association with increased corpus luteum vascularization was only found in sheep native to a high-altitude location. Administration of antioxidant vitamins resulted in a limited effect, which was restricted to decreased expression of oxidative stress biomarkers and luteal HIF-1alpha and VEGF immunoexpression. Conclusions: Exposure of the sheep to high-altitude hypobaric hypoxia for short or long time periods affects the development and function of the corpus luteum. Moreover, the observed association of oxidative stress with hypoxia and the absence of any significant effect of antioxidant vitamins on most anatomical and functional corpus luteum traits suggests that the effects of high altitude on this ovarian structure are mainly mediated by hypoxia. Thus, these findings may help explain the decrease in sheep fertility at a high altitude.

Pregnancies at high-altitudes are influenced by hypoxia and oxidative stress and frequently affected by IUGR. However, a common thought is that early pregnant women visiting altitude have no major complications for gestation development, since IUGR is developed during the second half of pregnancy. Thus, using a well-characterized sheep-model, we aimed to determine whether long- and/or short-term exposure to high-altitude may affect maternal steroidogenesis and therefore embryo-fetal growth from conception. The second aim was to differentiate the relative role of hypoxia and oxidative stress by assessing the effects of supplementation with antioxidant agents during this early-pregnancy stage, which were previously found to be useful to prevent IUGR. The results indicate that both long- and short-term exposure to high-altitude causes disturbances in maternal ovarian steroidogenesis and negatively affects embryo-fetal growth already during the very early stages of gestation, with the consequences being even worsened in newcomers to high-altitude. The supply of antioxidant during this period only showed discrete effects for preventing IUGR. In conclusion, the present study gives a warning for clinicians about the risks for early-pregnant women when visiting high-altitude regions and suggests the need for further studies on the effects of the length of exposure and on the interaction of the exposure with the pregnancy stage.

Understanding the botanical composition of herbivores’ diets and their nutritional quality is an important question in the development of sustainable strategies for the management of natural resources. In Chilean highland vicuña-grazed grasslands, there is little information in this regard and, therefore, this study aimed to determine the year-round profile of the diet’s botanical composition and quality. In highland grasslands, on an area of 21.9 ha, continuously grazed for 3.06 VU/ha/year (18°03′ S, 69°13′ W; 4425 m.o.s.l), twelve feces piles were sampled monthly and were analyzed through microhistology, and the nitrogen concentration [NF, OM basis] was determined. The botanical composition, diversity (J) and selectivity index (Ei) of the main species were estimated. Diets were composed of dry–grassland grasses (37.7%), wet–grassland grasses (36.6%), graminoids (14.3%) and forbs (10.2%). The diet diversity ranged from 0.79 (dry–winter) to 0.87 (wet–summer). The main dominant grassland species obtained negative Ei values. The annual mean value of [NF] was estimated as 1.82%, with a higher value in summer months (2.21%), which coincides with the physiological states of higher nutritional demand. The vicuñas behave like generalist ungulates, having a high degree of selectivity towards grass species, which mostly fulfill a nutritional role in subsistence and a functional role in survival, applying foraging strategies that allow them to obtain a better quality diet during the season of greatest nutritional demand.

The aim of the present study was to assess the reliability of fecal indices as predictors of nutrient intake in sheep under extensive grazing conditions. Fecal concentrations of 2,6-diaminopimelic acid (DAPAf), nitrogen (FN) and phosphorous (FP) were determined in four sheep kept in an extensive grazing system on annual Mediterranean grassland in the vegetative, reproductive and dry phenological stages. Metabolizable energy (MEI), crude protein (CPI) and phosphorus (PI) intake were calculated using the botanical composition, metabolizable energy, crude protein and phosphorus concentrations in each vegetal species making up the animal’s diet. Significant differences were observed in the nutrient intake for each phenological stage (p < 0.0001). The highest MEI, CPI and PI were observed during the vegetative stage (p < 0.0001). FN and FP were different in each phenological stage (p < 0.0001), with significant correlations observed between these variables (r = 0.916; p < 0.0001). Regressions among nutrient intake and fecal indices were significant, except in the cases of DAPAf and MEI, and DAPAf and CPI. Based on these results, fecal indices could be used to estimate nutrient intake in sheep under extensive grazing on annual Mediterranean grassland.

The re-introduction of domestic South American camelids (alpacas and llamas) in the central zone of Chile makes it necessary to study their behaviour and adaptability. Since it is fundamental to characterize the camelid's diet, the present work had as an objective the determination of the plant species selected by the alpacas (Lama pacos Linn.) in different phenological stages (vegetative, reproductive and dry season). The study was carried out over three years in a paddock of 2.5 ha of sparse shrubland dominated by Acacia caven (Mol.) Mol. and annual species in the herbaceous stratum, which were continually grazed by five male alpacas. The botanical composition and the forage dry matter available for grazing in the pasture was evaluated. Botanical composition of diets was estimated with the microhistological technique, using dung samples collected directly from the rectum. During the vegetative season, the most consumed plant species were annual and perennial grasses. In the reproductive season, the most important components of the diet were woody plant species, annual grasses and forbs. In the dry season, the diet was composed of a high percentage of woody plant species.

An analysis of the morphometric variables and zoometric index of a herd of creole goats in the Mediterranean area of central Chile was conducted, considering both females and males of three age categories (unweaned kids, growing kids, and adults). These variables were analysed using variance and principal components analysis. In most of the analysed variables, the effect of sex and age and their respective interaction was significant. The principal component analysis allowed to reduce the number of variables to be analysed (from 16 to 8 variables) establishing two major components, one related to the size and the other referring to the animal compactness which explained 70.86% of the data variability. The comparative analysis of the zoometric index allowed to characterise the animals of the studied herd as meat aptitude, mesacephalous (males), brachycephalic (females), mesomorphs, thin cannon bones, with the posterior body zone being less developed than the anterior body zone and great scapular development.

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Sheep and goat grazing diets on an annualMediterranean grassland containing tall wheatgrass (Thinopyrum ponticum (PODP.)). Cienc. Inv. Agr. 45(3):240-250. The development of mixed grazing systems is an interesting alternative for the utilization of rangelands with ecological and/ or economic limitations; therefore, the study of patterns and eating habits of different species in the same grazing area is important. A mixed grazing study was carried out on a Mediterranean grassland sown with Thinopyrum ponticum 30 years ago (Rinconada de Maipú, Chile 33º 28'S; 70º 51ʼ W) with the purpose of quantifying the botanical composition, dietary overlap and selectivity indexes of the main grass species consumed by goats and sheep. Trophic behavior was studied in seven young Suffolk Down rams, seven young Merino-Precoz rams and seven young Boer-Criollo bucks grazing together during three grassland phenological stages. During the grassland vegetative stage, diets were mainly composed of annual grasses and forbs. Perennial grasses dominated the animals' diets during the reproductive and dry grassland stages. The diversity of the goats' diets was higher than that of the sheep, demonstrating greater plasticity in their dietary habits. However, in this environment, both species behaved as generalist herbivores. The level of diet overlap between the sheep and goats was high, especially when grazing during the grassland reproductive and dry phenological stages, suggesting potential competition during lower forage quality stages.