Cobalt, as a trace element, is essential for rumen microorganisms for the formation of vitamin B12. In the metabolism of mammals, vitamin B12 is an essential part of two enzymatic systems involved in multiple metabolic reactions, such as in the metabolism of carbohydrates, lipids, some amino acids and DNA. Adenosylcobalamin and methylcobalamin are coenzymes of methylmalonyl coenzyme A (CoA) mutase and methionine synthetase and are essential for obtaining energy through ruminal metabolism. Signs of cobalt deficiency range from hyporexia, reduced growth and weight loss to liver steatosis, anemia, impaired immune function, impaired reproductive function and even death. Cobalt status in ruminant animals can be assessed by direct measurement of blood or tissue concentrations of cobalt or vitamin B12, as well as the level of methylmalonic acid, homocysteine or transcobalamin in blood; methylmalonic acid in urine; some variables hematological; food consumption or growth of animals. In general, it is assumed that the requirement for cobalt (Co) is expressed around 0.11 ppm (mg/kg) in the dry matter (DM) diet; current recommendations seem to advise increasing Co supplementation and placing it around 0.20 mg Co/kg DM. Although there is no unanimous criterion about milk production, fattening or reproductive rates in response to increased supplementation with Co, in some investigations, when the total Co of the diet was approximately 1 to 1.3 ppm (mg/kg), maximum responses were observed in the milk production.

Oregano additives could contain growth stimulating compounds for poultry, however, a great variation attributed to their main components is observed. The aim of the present study was to investigate the effect of oregano oil dietary supplementation on the productive variables, the height of the intestinal villi and the accumulation of antioxidant compounds in the breast of broilers. In total, 480 broilers were reared from 1 to 42 d of age and since the first day of life were allocated into four treatments, each with four replications of 30 birds. The formulated diet was based on corn and soybean meal and 0, 100, 200 or 400 mg of oregano oil per kg of feed were incorporated in the diets of treatment 1, 2, 3 and 4, respectively. Feed intake, weight gain, feed conversion and mortality rates were weekly recorded. At 21 and 42 days of age the intestinal villi height and antioxidant capacity in the chicken breast were measured. Oregano oil used contained 43.17% and 29.16% of thymol and carvacrol, respectively. Feed intake, weight gain, feed conversion rate and mortality were not affected by oregano oil dietary supplementation. The height of intestinal villi increased with the level of oregano oil supplementation (P<0.05). However, the size of the intestinal villi was greater in the duodenum compared to the other parts (P<0.05), and jejunum and ileum had the same height. Antioxidant capacity of chicken breast at the 6th week was increased in the group that was dietary supplemented with 400 mg of oregano oil per kg of feed.

There are limited published data in the bovine species on blood biological variables in response to intense work or after significant physical exertion. Lidia cattle, in addition to their exercise components, have some behavioral agonistic features that make them more susceptible to stress. The bullfight involves stress and exercise so intense that it causes significant changes in some metabolic variables. The study objective was to evaluate changes in blood biological variables in response to intense exercise and stress. After the fight in the arena, and once the bulls were dead (n = 438), blood samples were taken, and some biochemical and hormonal variables were determined in venous blood. A descriptive analysis was performed using the Statistica 8.0. computer program. The mean (±s.d.) results obtained were: total protein (85.8 ± 10.8 g/dL), albumin (3.74 ± 4.3 g/dL), triglycerides (39.65 ± 0.16 mg/dL), cholesterol (2.44 ± 0.03 mmol/L), glucose (22.2 ± 9.6 mmol/L), uric acid (340 ± 80 µmol/L), creatinine (236.9 ± 0.4 µmol/L), urea (5.93 ± 1.27 mmol/L), LDH (2828 ± 1975 IU/L), CK (6729 ± 10,931 IU/L), AST (495 ± 462 IU/L), ALP (90 ± 33 IU/L), GGT (50 ± 34 IU/L), ALT (59 ± 35 IU/L), cortisol (117.5 ± 46.6 nmol/L), and testosterone (20.2 ± 23.8 nmol/L). Most of the measured variables clearly increased; thus, we found severe hyperglycemia and increases in LDH, AST, GGT, and ALT enzymes, particularly in CK. The increases in all these variables are justified by the mobilization of energy sources, tissue/muscle damage, and dehydration due to continued stress and intense exercise.

The presence of pathogens in fecundation hives represents a source of infection for queen bees. The objective of this investigation was to determine the prevalence of Varroa, Nosema, and Acarapis in hives for the production of mating nuclei (HPMN). 239 samples of adult bees of 17 apiaries of a queen bee breeding system were analyzed during the winter and summer of 2016. The prevalence of Varroa and Nosema was higher in winter (79.1% and 55.4%, respectively) than in summer (65.9% and 33.0%, respectively). However, Acarapis was not found. Varroa infestation was 2.55 ± 0.82 mites/100 bees, and Nosema 145 ± 24 × 10³ spores/bee (Standard deviation of the mean). The probability of finding Nosema, in the presence of Varroa, was 3.8 and 1.1 times higher in winter than in summer, respectively. We, therefore, conclude that HPMN has a higher incidence of varroasis and nosemosis during winter and nosemosis increases in the presence of varroasis. We, on the other hand, consider acariosis, absent in the region of study.

El objetivo del estudio fue evaluar el efecto de sustituir el grano de sorgo (SG) con fruto de Guazuma ulmifolia(GU) en dietas para corderos a base de alfalfa (AA) o maralfalfa (MA) sobre la digestibilidad y el comportamiento productivo. Se utilizaron cuatro ovinos machos Blackbelly de 35 kg de peso promedio, con cánula ruminal para determinar la digestibilidad in vivo, in vitroe in situde la materia seca. En la prueba de comportamiento productivo se utilizaron 20 corderos Pelibuey de 15 ± 1.5 kg de peso bajo un diseño completamente al azar. La composición porcentual de las dietas experimentales fue: dieta 1: 55 de MA, 20 de GU y 8 de SG; dieta 2: 55 de MA, 8 de GU y 20 de SG; dieta 3: 55 de AA, 20 de GU y 8 de SG y dieta 4: 55 de AA, 8 de GU y 20 de SG. Todas las dietas contenían melaza de caña de azúcar (5%), pasta de canola (9%) y mezcla de minerales (3%). La sustitución de SG por GU en la dieta no afectó la digestibilidad de la materia seca ni el comportamiento productivo de los ovinos (p > 0.05). Pero los valores de digestibilidad y comportamiento productivo fueron inferiores (p < 0.05) con la inclusión de MA en las dietas. El grano de sorgo puede ser sustituido hasta en un 20% por el fruto de Guazuma ulmifoliaen dietas de corderos, con niveles altos y bajos de fibra, sin afectar la digestibilidad de la materia seca ni el comportamiento productivo.