Volumen 6, Número 1

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  • Ítem
    Inóculos bacterianos: una alternativa para mejorar el proceso fermentativo en los ensilajes tropicales
    (2013-06-04 00:00:00) Tobía R., Carlos; Vargas González, Emilio
    Milk Production systems depend on good quality forages. Silage is a great alternative for storing forages throughout the year. The fermentation process in silage, presents four phases (aerobic, fermentative, stabilization and deterioration). The use of lactic acid producing bacteria, as an additive helps optimizing the fermentation process. Specially when tropical forages are used, due to the lower natural concentration of lactic acid bacteria and fermentable carbohydrates. These additives stimulate fermentation and decrease aerobic deterioration. Forages or other products stored as silage suffer damage and a reduction in its nutritional values as well as risk in pollution. Therefore, increasing stabilization in silage is of great interest of producers for forage conservation.
  • Ítem
    Composición de los subproductos de trigo utilizados en la alimentación animal en Costa Rica
    (2013-06-04 00:00:00) Vargas González, Emilio
    Composition of wheat by-products used as feed stuffs in Costa Rica. This study was conducted to estimate the nutritional content and their variability of different wheat and bakery by products used as feedstuffs in Costa Rica. Wheat shorts, middlings and brand were studied as well as cookies, crackers and bread. Results clearly indicated that wheat shorts had the highest nutritional value, due to its low fiber and ashes content as well as its high protein, non structural carbohydrates and energy values. Wheat shorts protein levels, NDF, NSC and DE for swine were 79.4;29.7; 45.7% and 3.570 Kcal/kg; for wheat brand values were 18.6; 49.7;24.0% and 2.878 Kcal/kg respectively. Bakery by products (crackers and cookies) showed the highest content of nutrients with high fat levels, NSC and DE for swine (13.1; 77.66% and 4.454 Kcal/kg). The greatest variability in the nutrients content was observed in the ether extracts of the bakery by products. Therefore, it was concluded that all these materials are good nutrient sources for swine, but fiber, fat and energy could vary, indicating that quality control of them should be carefully monitored.
  • Ítem
    Caracterización de los componentes forrajeros de cuatro asociaciones gramíneas/ Arachis pintoi
    (2013-06-04 00:00:00) Sánchez González, Jorge Manuel; Villareal, Milton; Soto, Henry
    The association of the herbaceous legume Arachis pintoi CIAT 17434with tropical grasses has a great potential to improve cattle production in grazing systems. This study was conducted to characterize the nutritional quality of these associations and to obtain useful information to improve the feeding strategies for cattle in the humid tropics of Costa Rica. The experiment was carried out at the La Balsa farm of the lnstituto Tecnológico de Costa Rica, located in an area classified as Humid Tropic. Annual average rainfall in the zone is 3062 mm and average temperature is 26,7 C. Eight treatments conformed as a factorial arrangement of four grass/Arachis pintoi CINI 17494 associations and two stocking rates (3,0 and 1,5 A.U.) were evaluated. Grasses under evaluation were Cynodon nlemfuensis, Brachiaria dictyoneura CIAT 6133, Brachiaria brizantha CIAT 6780 and Brachiaria brizantha CIAT 664. Paddocks were grazed every 35 ciays for 5 to 7 days. Composed samples were taken at each grazing cycle and they were analysed for Crude Protein (AOAC 19g4, Neutral Detergent Fiber and Lignin (Van Soest y Robertson 1984), Non-Fiber Carbohydrates (Van Soest et al. 1991). Total Digestible Nutrients were estimated by the model developed by Weiss et al. (7992) and the Digestible and Metabilizable Energy contents by standard NRC (1989) procedures. Crude Protein content was higher (P<0.05) for Arachis pintoi than for the grasses evaluated (average levels were 79.4 and7.8/" respectively). Mean Neutral Detergent Fiber levels in grasses were 73.5: meanwhile in Arachis pintoi were 57.9"/", these values were significantly different (P<0.05 Lignin content was higher (P<0.05) in Arachis pintoi than in the grasses with which this legume was associated, mean values were 10.6 and 6.5% respectively. Arachis pintoi showed a mean value of Non-Fiber Carbohydrates of 28.9% which was significantly (P<0.05) higher than the level of 11.4% obtain for the grasses. Energy levels were higher (P<0.05) in the legume than in the grasses. Total Digestible Nutrients were 51.1 and 48.7%. Digestible Energy 2.25 and 2.15 Mcal/kg of DM. Metabolizable Energy 1.83 and 1.72 Mcal/kg of DM for Arachis pintoi and for the grasses with which the legume was associated, respectively, Arachis pintoi increases Crude Protein. Non-Fiber Carbohydrates and Energy contents of the legumegrass associations. This has important implications for cattle production based on grazing, since these are the most limiting nutrients in production systems based on tropical pastures.
  • Ítem
    Utilización del pejibaye (Bactris Gasipaes) en la alimentación animal
    (2013-06-04 00:00:00) Arroyo Oquendo, Carlos; Murillo R., Mario
    Partial or total substitution of corn and sorghum by pejibaye meal was evaluated in broilers, pullets, laying hens, geese, pigs and cattle; the meal was obtained from the processing of the whole fruit. Satisfactory results were obtained with pejibaye meal among the species evaluated. Even with a total substitution for maize or sorghum, values in feed consumption, weight gain, and feed conversion were positive. The meal manufacturing process must utilize proper thermal treatment (over 100.C for 20 min) of the fruit by cooking or by extrusion, to obtain the best meal, non thermal treated meals caused low feed consumption and poor feed conversion, due to the presence of inhibiting proteolytic factors, affecting primarily young individuals. Fiber levels in the diet must be controlled, due to an increase in the amount of fibrous parts of the brunch can affect it. If fiber and grinding are controlled, pejibaye meal can totally substitute com and sorghum in animal diets. This is an important issue if it is taken into account that must of feed stuffs are imported.
  • Ítem
    Nutrición energética del ganado lechero
    (2013-06-04 00:00:00) Sánchez González, Jorge Manuel
    Energy nutrition of dairy cattle. A review. Energy is a subtle term and is defined as the capacity for doing a work. In dairy cattle nutrition, feeds have that capacity and the work is the maintenance of the cow, milk production and reproduction. About 75% of dry matter consumed by the cow is used by the organism to generate and meet its energy requirements. Tropical grasses are characterized by having low or medium energy levels, so energy supplementation of animals grazing tropical grasses requires special attention in order to get good production levels. Energy contents of grasses are difficult to estimate and it is not possible to do it through regular laboratory analytical methods. However, lineal equations based on the ADF content of forages are frequently used to achieve this goal, as well as mechanistic models using different chemical fractions of forages. Cows experience a negative energy balance during the first trimester of lactation, which is compensated by energy body reserves mobilization. A cow can produce 8 to 10 kg of milk from the energy supplied by a kg of adipose tissue, or an average of 636 kg per each unit of body condition score. Milk production from each unit of body condition score follows an exponential trend, hence the importance of a proper body condition at calving. Adipose tissue mobilization as well as low feed intake during early lactation makes fresh cows more tolerant to heat stress. To have a good production cycle, cows should begin their lactation with a body condition score of 3.5, then this will drop to 2.5 by the time of first insemination. As lactation proceeds, cows should begin to replenish their energy and fat reserves to the point where they have a body score of 3 and remain at this score or near throughout the majority of lactation. In late lactation animals should gain weight to be dried off at 3.5. If a cow calves in a poor body condition (<3), or her energy nutrition is optimal during early lactation, she will suffer a severe negative energy balance, which will limit her to produce as much milk as the dietary energy will allow. Moreover, she will be more susceptible to metabolic diseases such as ketosis and delays in returning to ovarian activity. Likewise, when animals are over conditioned during late lactation and calve with a body condition score of 4 or higher, they are predisposed to suffer metabolic imbalances such as ketosis or displaced abomasum and severe reproductive problems during the peripartum
  • Ítem
    Hipomagnesemia un desbalance metabólico subestimado en la producción de ganado lechero en Costa Rica
    (2013-06-04 00:00:00) Sánchez González, Jorge Manuel
    Hypomagnesemia. A metabolic imbalance underestimated in dairy herds in Costa Rica. A review. Hypomagnesemia is a metabolic disorder characterized by a reduction in blood and cerebrospinal fluids magnesium levels, affecting the central nervous system. Hypomagnesemic tetany mainly affects old and high producing cows and incidence can reach epidemic proportions. When magnesium levels drop between 1.8 to 1.1 mgl100 ml, the metabolic imbalance is considered moderate and the animal reduces feed intake, is nervous and milk fat synthesis and total milk production are reduced. This condition predisposes to milk fever. If magnesium levels fall below 1.1 mg/100 ml neuromuscular function is affected and the animals show tetanic spams of the muscules and usually lay with the head arched back and the legs paddling. The eyelids flutter and there is nystagmus. If animals are not treated immediately mortality is high. The most effective treatment for the hypomagnesemic cow is the 500 ml injection of a solution of calcium borogluconate (8 to 10 g calcium) and magnesium borogluconate (1.5 to 4 g of magnesium). Injections should be administered slow and intravenously. To prevent relapses is recommended the subcutaneous injection of L00 to 200 ml of a 20 to 50% magnesium sulfate solution. Since no hormonal mechanisms are in charge of keeping the magnesium homeostasis in the organism, the mineral should be always supplied in the diet of the animals in order to maintain the normal plasma levels (1.8 to 2.4mg/1OO ml). Magnesium level in the dairy cattle diet should be 0.25% of dry matter when the K:(Ca+Mg) ratio is below 2.2.If this relationship is higher the level of the element should be increased to 0.30%. Magnesium absorption in the rumen epithelium depends on the concentration of magnesium in solution in the rumen fluid and the activity of the magnesium transport mechanism, which is related to sodium. Among factors affecting the concentration of magnesium in solution in the rumen fluid are the amount of this mineral in the diet, rumen pH and the concentration of unsaturated fatty acids in the forages. Magnesium transport across the rumen epithelium is affected by the sodium: potassium ratio in the diet, as well as the ingestion of lush high moisture pastures, which increases the rate of passage of feed from the rumen, reducing the absorption of magnesium. Most of the forages in the Humid Tropics and the Highlands of Costa Rica have conditions that predispose cows to suffer hypomagnemia. Moreover, most of the soils in these areas ale magnesium deficient (less than 1 mgl100 ml of soil). In those dairy herds where this imbalance is a problem, it is recommended to increase magnesium intake through drinking
  • Ítem
    La fibra en la alimentación del ganado lechero
    (2013-06-04 00:00:00) Cruz C., Marcela; Sánchez González, Jorge Manuel
    Fiber in Dairy Cattle Nutrition. A review Fiber or cell wall is essential in dairy cattle nutrition as well as in ruminants in general. This nutritional fraction consists of cellulose, hemicellulose, lignin, lignified nitrogen, cutin and silica. Its importance in dairy cattle nutrition relies on its physical and chemical properties. Cell wall stimulates saliva secretion as well as buffers, which stabilizes ruminal pH. Likewise, it undergos microbial fermentation in the rumen to produce volatile fatty acids, which are the main energy source for the ruminant. Neutral detergent and acid detergent fiber are the main cell wall fractions used in ration formulation. Fiber has important implications in dairy cattle nutrition, because it helps to maintain normal rumen function and motility, milk production and its composition, and allows to estimate feed intake as well as the energy content of feeds and forages. Fiber level in the diet has to be such that keeps the health of the animal, but at the same time does not interfere with feed intake nor energy density of the diet. Fiber requirements depends on body condition of the cow, particle size of the feed, buffer capacity of the diet, feed intake frequency as well as economical aspects. NRC (1989) recommends levels of 19 Io 27% of ADF and 25 to 35% of NDF in dairy rations, depending on milk production level. Likewise, it suggests that 75% of total NDF has to be supplied by forages. However, recent research shows that forage NDF in the diet could be reduced to 75-16% of dry matter, when NDF content of the total diet is 28 % or higher. Nonforage fiber sources may be used to reduce the forage NDF levels to 60-65% of total NDF. According to some authors nonforage fiber sources are 40 to 80% as effective as forage fiber. Different studies indicate that the level of NDF in the diet depends on its quality, so diets having legumes as main fiber source, require higher levels of NDF than those with grasses/ since grasses have higher effective fiber levels. Particle size must be bigger than 0.95 cm to prevent milk fat depression. Another factor to consider when NDF requirements are to be established is the source of non fiber carbohydrates, if this nutritional fraction consists of readily fermented starch, fiber level in the ration has to be higher. Recommendations of dairy cattle fiber requirements has to be taken as guides, since the dairy herd has its own nutritional needs because of its milk production level, diet quality and feeding practices at the farm.