¿Cómo monitorear el movimiento del ganado en un mosaico de áreas boscosas con GPS en combinación con SIG?

El manejo de bosques de Piñon-Juniper (PJ) ocupa más de 30 millones de hectáreas en el oeste de Estados Unidos. Este ecosistema constituye un importante recurso para la producción y conservación de vida silvestre. Sin embargo, estos han cambiado considerablemente los últimos 30 años, principalmente para manejar ganado en pastoreo. El objetivo fue determinar la cobertura de dosel (TCC) y monitorear, durante la primavera, el uso del ganado del paisaje arbolado. El estudio se realizó en una pastura de 146 ha de la zona central de Nuevo México. La TCC de PJ se determinó a partir de ortofotos digitales recientes usando Feature Analyst® para ArcGIS® 9.1. El sitio de estudio fue segmentado en celdas de 1 ha para mapear cobertura arbórea. Ocho vacas, equipadas con GPS, fueron rastreadas durante 31 días a intervalos de 5 min. Una sección de la pastura con cobertura arbórea mayor que 30 % se utilizó para describir la relación distribución de pastoreo y cobertura de dosel. Se encontró una relación exponencial negativa significativa entre TCC y el uso relativo del ganado (y = 450,41e-12,329x). La cubierta arbórea explicó 50,1 % de la variación en la utilización relativa por el ganado de las celdas. La mayoría de las posiciones animales registradas en áreas dominadas por PJ ocurrieron en celdas con 30-50 % de TCC. Una cobertura del dosel de 50 % podría proporcionar un equilibrio adecuado entre la permanencia y el consumo de  forraje para el ganado durante la primavera

Effects of administration of a growth promoting implant during the suckling phase or at weaning on growth, reproduction, and ovarian development in replacement heifers grazing native range

Management strategies utilized during pre-breeding development of replacement heifers can impact fertility and the ovarian reserve. Angus- Hereford crossbred heifers (n = 233) were utilized over a 3-yr period to determine the effects of administration of a growth promoting implant at either branding or weaning on growth, reproduction, and ovarian development. Heifer calves were randomly assigned to one of three treatments: 1) nonimplanted controls (CON; n = 79), 2) implanted at approximately 2 mo of age (average calf age = 58 d) with Synovex-C (BIMP, n = 82), or 3) implanted at approximately 7 mo of age (average calf age = 210 d) with Synovex-C (WIMP; n = 72). In years 2 and 3, a subset of heifers (year 2 n = 16; year 3 n = 14) were unilaterally ovariectomized. Heifers implanted at 2 mo of age were heavier at weaning, yearling (mid-February; average calf age = 332 d), and at the beginning of the breeding season (P \u3c 0.01) compared to CON and WIMP heifers. Average daily gain (ADG) was similar among treatments from weaning to yearling and weaning to the start of the breeding season (P ≥ 0.61); however, WIMP heifers had increased (P = 0.05) ADG from yearling to the start of the breeding season compared to BIMP heifers. Antral follicle count and reproductive tract scores were not influenced by implant treatment (P ≥ 0.18). Response to synchronization of estrus was increased (P = 0.02) in WIMP compared to CON heifers, with BIMP heifers similar to all other treatments. First service conception rates tended to be increased (P = 0.09) in CON heifers compared to WIMP heifers, with BIMP heifers similar to CON and WIMP. Final pregnancy rates were similar (P = 0.54) among treatments. A treatment × yr interaction was detected (P = 0.01) for the number of primordial follicles/section with increased primordial follicles in WIMP heifers in year 3 compared to BIMP and WIMP heifers in year 2 and CON heifers in year 3, as well as in BIMP compared to WIMP heifers in year 2. Utilization of growth promoting implants did not negatively impact postweaning reproductive development or compromise pregnancy rates in beef heifers. Based on these results, administration of a growth promoting Synovex-C implant at 2 mo of age may allow for increased body weight at weaning, without hindering reproductive performance

Genetic effects on gene expression across human tissues

Characterization of the molecular function of the human genome and its variation across individuals is essential for identifying the cellular mechanisms that underlie human genetic traits and diseases. The Genotype-Tissue Expression (GTEx) project aims to characterize variation in gene expression levels across individuals and diverse tissues of the human body, many of which are not easily accessible. Here we describe genetic effects on gene expression levels across 44 human tissues. We find that local genetic variation affects gene expression levels for the majority of genes, and we further identify inter-chromosomal genetic effects for 93 genes and 112 loci. On the basis of the identified genetic effects, we characterize patterns of tissue specificity, compare local and distal effects, and evaluate the functional properties of the genetic effects. We also demonstrate that multi-tissue, multi-individual data can be used to identify genes and pathways affected by human disease-associated variation, enabling a mechanistic interpretation of gene regulation and the genetic basis of diseas

Genetic effects on gene expression across human tissues

Characterization of the molecular function of the human genome and its variation across individuals is essential for identifying the cellular mechanisms that underlie human genetic traits and diseases. The Genotype-Tissue Expression (GTEx) project aims to characterize variation in gene expression levels across individuals and diverse tissues of the human body, many of which are not easily accessible. Here we describe genetic effects on gene expression levels across 44 human tissues. We find that local genetic variation affects gene expression levels for the majority of genes, and we further identify inter-chromosomal genetic effects for 93 genes and 112 loci. On the basis of the identified genetic effects, we characterize patterns of tissue specificity, compare local and distal effects, and evaluate the functional properties of the genetic effects. We also demonstrate that multi-tissue, multi-individual data can be used to identify genes and pathways affected by human disease-associated variation, enabling a mechanistic interpretation of gene regulation and the genetic basis of disease

Seasonal Mass, Performance under Grazing, and Animal Preference for Irrigated Winter Cereal Forages under Continuous Stocking in a Semiarid, Subtropical Region

Winter annual cereal forages perform well in semiarid, subtropical regions forming, a significant component of livestock operations for autumn through spring stocker cattle (Bos taurus) backgrounding in either grazeout or graze-grain systems; however, little information is available about their relative seasonal productivity and animal preference. Seasonal growth and regrowth under grazing and grazing preference of oat (Avena sativa), rye (Secale cereale), triticale (×Triticosecale rimpaui Wittm.), and wheat (Triticum aestivum) were compared over two years at New Mexico State University’s Rex E. Kirksey Agricultural Science Center at Tucumcari. Seasonlong (Nov–Apr) average forage dry matter yield was rye > oat > wheat > triticale (5.03, 4.44, 3.58, and 2.79 Mg ha−1, respectively; p < 0.0001). Rye also had greater average monthly growth than the other cereals, among which there was no difference (1.58, 1.05, 0.96, and 0.85 Mg ha−1 mo−1 for rye, oat, wheat, and triticale, respectively; p < 0.0331). Growth of ungrazed cereals was reduced in mid-winter and regrowth of grazed forage did not equal removal by growing cattle. When given a preference and allowed to deplete available forage, growing cattle preferred oat followed by rye, then wheat and triticale. Regrowth of grazed forage did not differ among cereals

A Comparison of Native Grass and Triticale Pastures during Late Winter for Growing Cattle in Semiarid, Subtropical Regions

Forage-based beef production is one of the most productive agricultural systems, especially in semiarid, subtropical environments, yet it is temporally variable due to climatic factors. Dormant native perennial warm-season grasses are available for grazing from autumn through spring; however, their protein concentration is inadequate to support growing cattle. Winter cereal forages, such as triticale [×Triticosecale Wittm. ex A. Camus (Secale × Triticum)], can fill fall through spring forage gaps with sufficient protein concentration. Triticale productivity was evaluated, and beef stocker performance on triticale was compared with supplemented native grassland for late winter pasture in each of three years at New Mexico State University’s Rex E. Kirksey Agricultural Science Center in Tucumcari, NM USA. Study results indicated that triticale pasture forage mass varied over the three years due to precipitation and different triticale planting dates each year, influencing the length of grazing period. Triticale provided late winter average daily gain approximately twice that of cattle grazing dormant native grass with protein supplementation (0.70 vs. 0.36 kg hd−1 d−1, p < 0.0001). Therefore, triticale can be utilized to provide adequate growth of young calves without the added costs of supplementation

A Comparison of Native Grass and Triticale Pastures during Late Winter for Growing Cattle in Semiarid, Subtropical Regions

Forage-based beef production is one of the most productive agricultural systems, especially in semiarid, subtropical environments, yet it is temporally variable due to climatic factors. Dormant native perennial warm-season grasses are available for grazing from autumn through spring; however, their protein concentration is inadequate to support growing cattle. Winter cereal forages, such as triticale [&times;Triticosecale Wittm. ex A. Camus (Secale &times; Triticum)], can fill fall through spring forage gaps with sufficient protein concentration. Triticale productivity was evaluated, and beef stocker performance on triticale was compared with supplemented native grassland for late winter pasture in each of three years at New Mexico State University&rsquo;s Rex E. Kirksey Agricultural Science Center in Tucumcari, NM USA. Study results indicated that triticale pasture forage mass varied over the three years due to precipitation and different triticale planting dates each year, influencing the length of grazing period. Triticale provided late winter average daily gain approximately twice that of cattle grazing dormant native grass with protein supplementation (0.70 vs. 0.36 kg hd&minus;1 d&minus;1, p &lt; 0.0001). Therefore, triticale can be utilized to provide adequate growth of young calves without the added costs of supplementation

Temperament Affects Rangeland Use Patterns and Reproductive Performance of Beef Cows

On the Ground • The American beef industry is paying more attention to cattle temperament, but studies examining relationships between temperaments and grazing behavior or animal performance on rangelands are limited. • We studied range beef cow temperaments using the behavioral syndromes framework. Cows classified into behavioral type groups on the basis of a suite of correlated behaviors showed contrasting rangeland use patterns and different reproductive efficiency. These differences resulted in temperament-related culling rates over time. • We argue that the behavioral syndromes conceptual framework could be a valuable tool to advance current understanding about how cattle temperaments are related to grazing patterns and animal performance on rangeland.The Rangelands archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform March 202