13,14-Dihydro-15-Keto Prostaglandin F-2 alpha Release in Response to Oxytocin Challenge Early Post-Partum in Anoestrous Nelore Cows Submitted to Temporary Calf Removal and Progesterone Priming

The study evaluated, in early post-partum anoestrous Nelore cows, if the increase in plasma oestradiol (E2) concentrations in the pre-ovulatory period and/or progesterone priming (P4 priming) preceding ovulation, induced by hormonal treatment, reduces the endogenous release of prostaglandin PGF(2)alpha and prevents premature lysis of the corpus luteum (CL). Nelore cows were subjected to temporary calf removal for 48 h and divided into two groups: GPE/eCG group (n = 10) and GPG/eCG group (n = 10). Animals of the GPE/eCG group were treated with a GnRH agonist. Seven days later, they received 400 ID of eCG, immediately after PGF(2)alpha treatment, and on day 0, 1.0 mg of oestradiol benzoate (EB). Cows of the GPG/eCG group were similarly treated as those of the GPE/eCG group, except that EB was replaced with a second dose of GnRH. All animals were challenged with oxytocin (OT) 9, 12, 15 and 18 days after EB or GnRH administration and blood samples were collected before and 30 min after OT. Irrespective of the treatments, a decline in P4 concentration on day 18 was observed for cows without P4 priming. However, animals exposed to P4 priming, treated with EB maintained high P4 concentrations (8.8 +/- 1.2 ng/ml), whereas there was a decline in P4 on day 18 (2.1 +/- 1.0 ng/ml) for cows that received GnRH to induce ovulation (p < 0.01). Production of 13,14-dihydro-15-keto prostaglandin F-2 alpha (PGFM) in response to OT increased between days 9 and 18 (p < 0.01), and this increase tended to be more evident in animals not exposed to P4 priming (p < 0.06). In conclusion, the increase in E2 during the pre-ovulatory period was not effective in inhibiting PGFM release, which was lower in P4-primed than in non-primed animals. Treatment with EB promoted the maintenance of elevated P4 concentrations 18 days after ovulation in P4-primed animals, indicating a possible beneficial effect of hormone protocols containing EB in animals with P4 priming.

Brazil: the challenge of improving export performance

Includes bibliography

Latin America's experience in dispute settlement within WTO: the cases of technical standards, sanitary and phytosanitary measures and intellectual property

Includes Bibliography

The challenge of finding robust poverty indicators for rapid monitoring of changes

Includes bibliography

América Latina: el desafío de socializar el ámbito doméstico = Latin America: the challenge of socializing the home environment

Incluye Bibliografía

The challenge of gender equity and human rights on the threshold of the twenty-first century

Includes bibliography

Human trafficking: a regional challenge

Includes bibliography

Ruminal acidosis challenge impact on ruminal temperature in feedlot cattle

The objective of this experiment was to determine if ruminal temperature rise coincides with pH reduction using an acidosis challenge model. Twelve ruminally cannulated steers (518 ± 28 kg BW) were administered ruminal temperature-monitoring devices that recorded temperature every 2 min. Steers were fed a 63% concentrate diet at 1.6% BW for 20 d before being randomly assigned to 1 of 3 acidosis challenge treatments: no dietary change (CON), onehalf of daily DMI replaced with cracked corn (HALF), or all of daily DMI replaced with cracked corn (CORN). The challenge was initiated by ruminally dosing steers with their treatment diets. Ruminal pH and rectal temperatures (Trec) were recorded every 3 h for 72 h. All steers were offered CON diets at 24 and 48 h after challenge. Ruminal pH showed a treatment × day effect (P = 0.01). Ruminal pH of CORN steers was lower (P = 0.03) than that of HALF steers on d 1, was lower (P ≤ 0.004) than that of HALF and CON steers on d 2, and tended to be lower (P ≤ 0.10) than that of HALF and CON steers on d 3. Treatment did not affect (P ≥ 0.42) RecT. Ruminal temperature (Trum) showed a treatment · d-1 × h-1 after feeding interaction (P < 0.01). At 3 h after challenge, Trum of CORN and HALF steers was higher (P ≤ 0.01) than that of CON steers. On d 2, Trum of CORN steers was higher (P ≤ 0.03) than that of CON between 6 and 12 h after feeding. From 15 to 21 h after feeding on d 2, Trum of HALF steers was higher (P < 0.01) than that of CORN and CON steers. On d 3, at the time of feeding until 3 h later, Trum of CORN steers was lower (P ≤ 0.04) than that of all other steers. Rectal temperature was correlated (P ≤ 0.01) with Trum on all days for CON and CORN steers. Ruminal pH was negatively correlated (P ≤ 0.04) with Trec on d 2 and Trum on d 1 in CORN steers, and Trum was negatively correlated (P ≤ 0.02) with ruminal pH in HALF and CON steers on d 1 and 3, respectively. The amount of time above Trum of 39.0°C or 39.45°C was correlated (P ≤ 0.05) with the time spent below a ruminal pH of 5.5 in CORN steers; however, time above Trum of 39.0°C did not differ (P = 0.87) among treatments. Results indicate that there is a negative relationship between Trum and ruminal pH during an acidotic episode; therefore, Trum monitoring can detect a potential acidotic episode. © 2012 American Society of Animal Science. All rights reserved.

Coordinación de decisiones en economías mixtas: un desafío para la cooperación del PNUD con América Latina y el Caribe = Decisions co-ordination in mixed economies: a challenge for UNDP co-operation with Latin America and the Caribbean

Exposicion del Jefe de la Division del Programa Regional y del Caribe de Habla Inglesa del PNUD en la inauguracion del Coloquio, en la cual se refiere a la tarea encomendada a este organismo acerca de la coordinacion de la cooperacion en las nuevas tecnicas de planificacion del desarrollo y de la insercion de America Latina y el Caribe en la economia internacional, que la problematica actual requiere.

Daily biofilm control and oral health: Consensus on the epidemiological challenge-Latin American Advisory Panel

Our understanding of dental plaque biofilm has evolved since the nonspecific plaque hypothesis that considered plaque as a nonspecific mass of native microorganisms that, because of lack of oral hygiene, builds up in proportions great enough to overcome the host resistance threshold and affect the tooth structure and tooth supporting tissues. A great diversity of microorganisms-over 700 species-was detected in the oral cavity, and evidence shows that the investigation of specific microorganisms or associations of microorganisms as etiological agents for periodontal diseases and caries is not a simplistic approach. Although clinical evidence shows that oral mechanical hygiene is fundamental to prevent and control caries and periodontal disease, it is important to highlight that optimal control is not achieved by most individuals. Thus the complementary use of chemotherapeutic agents has been investigated as a way to overcome the deficiencies of mechanical oral hygiene habits, insofar as they reduce both plaque formation and gingival inflammation, and represent a valid strategy to change the biofilm and maintain dental and periodontal health. The role of the dental professional is to monitor patients and offer them the best recommendations to preserve oral health throughout their life. With this in mind, chemical control should be indicated as part of daily oral hygiene, together with mechanical procedures, for all individuals who present supragingival and/or subgingival biofilm, taking into account age, physical and/or psychological limitations, allergies, and other factors.

The challenge of orthodoxy and the ideas of José Medina Echavarría

Includes bibliography

The challenge of industrial competitiveness

Includes bibliography

Post-conflict peace-building: a challenge for the United Nations

Includes bibliography

The competitive challenge for Brazilian industry

Includes bibliography