The greening of the “barrios”: Urban agriculture for food security in Cuba

Urban agriculture in Cuba has rapidly become a significant source of fresh produce for the urban and suburban populations. A large number of urban gardens in Havana and other major cities have emerged as a grassroots movement in response to the crisis brought about by the loss of trade, with the collapse of the socialist bloc in 1989. These gardens are helping to stabilize the supply of fresh produce to Cuba's urban centers. During 1996, Havana's urban farms provided the city's urban population with 8,500 tons of agricultural produce, 4 million dozens of flowers, 7.5 million eggs, and 3,650 tons of meat. This system of urban agriculture, composed of about 8,000 gardens nationwide has been developed and managed along agroecological principles, which eliminate the use of synthetic chemical pesticides and fertilizers, emphasizing diversification, recycling, and the use of local resources. This article explores the systems utilized by Cuba's urban farmers, and the impact that this movement has had on Cuban food security.     

Effect of phase-feeding crude protein on performance and carcass characteristics of crossbred beef bulls: an application to reduce nitrogen compounds in beef cattle diets

Beef cattle (24) with an average initial body weight of 417?±?54 kg were assigned in a 2?×?2 factorial design with six repetitions. The factors studied were two levels of CP: 11 (low CP) or 13 % (high CP) in the initial feedlot phase (days 1–36) and in the final phase (days 37–72). After 36 days, half of the bulls fed with each level of CP were selected to reverse the CP level. No interaction was observed (P?>?0.05) between the level of protein in the initial and final phases on the intake of the nutrients evaluated. There was no effect (P?>?0.05) of the protein levels in the initial and final phases on intake of dry matter, organic matter, CP, non-fiber carbohydrates, and total digestible nutrients. No differences were observed among treatments (P?>?0.05) for average daily gain (X = 1.99 kg/day) and carcass traits. We conclude that it is possible to feed Holstein-Zebu crossed bulls with an average daily gain of approximately 2 kg using a fixed level of 11 % CP during the entire feedlot period, and this diet is economically viable and environmentally sound.     

Bovine Colostrum Supplementation Does Not Influence Serum Insulin-like Growth Factor-1 in Horses in Race Training

Bovine colostrum (BC) is a commonly used food supplement in humans for both immune support and athletic performance enhancement; the latter effect has been attributed in some studies to an increase in the anabolic cytokine Insulin-like Growth Factor-1 (IGF-1). The aim of the present study was to determine the effect of BC supplementation on serum IGF-1 in racing horses. Five serum IGF-1 samples were collected from 12 horses in race training every 2 weeks over an 8-week period from November to January. Six horses received BC supplementation for 4 weeks, starting at the 2-week point. The expected seasonal IGF-1 decrease over the November to January study period was observed, but there was no effect of BC supplementation on serum IGF-1 concentrations as compared with the untreated controls.     

Natural selection favors a newly derived timeless allele in Drosophila melanogaster

Circadian and other natural clock-like endogenous rhythms may have evolved to anticipate regular temporal changes in the environment. We report that a mutation in the circadian clock gene timeless in Drosophila melanogaster has arisen and spread by natural selection relatively recently in Europe. We found that, when introduced into different genetic backgrounds, natural and artificial alleles of the timeless gene affect the incidence of diapause in response to changes in light and temperature. The natural mutant allele alters an important life history trait that may enhance the fly's adaptation to seasonal conditions.     

Induction of variability in chimeric Aster cordifolius `White Elegans' through somaclonal variation

A protocol was developed for plant regeneration from leaf explants (laminaand petiole) of Aster cordifolius cultivar `White Elegans', which ischimeric for chromosome number and the ligulate flower colour. Explantswere cultured on MS or Gamborg's B5 medium in presence of IAA, 2,4-Dand BAP, alone or in combination. The highest frequency of shootregeneration was obtained on B5 medium supplemented with 2,4-D(0.09 mg l^-1) and BAP (1.8 mg l^-1). After the invitro rooting stage and acclimatization, 90% of plantlets survived in thegreenhouse. The regeneration process occurred by indirect organogenesisas shown by cyto-histology. The regenerants maintained the originalchimerism for chromosome number. Pink flowers instead of theexpected white ones were obtained in all regenerants. Ahypothesis for the uniform colour change is discussed. Variations weredetected in the regenerant generation (R₀) for quantitative characterssuch as capitulum and disc diameters, and number of ligulate flowers. SinceAster can be vegetatively propagated, selection of variants in R₀can provide interesting material for breeding purposes.     

Increasing resistance to Fusarium crown and root rot in asparagus by gametophyte selection

In garden asparagus, Fusarium crown and root rot is the main cause of crop decline. Since chemical treatments are inefficient, efforts should focus on the development of resistant cultivars to control the disease. Toxic culture filtrate (TCF) of F. oxysporum has affected asparagus pollen germination and tube growth. Consequently, gametophyte selection was evaluated to ascertain if the application of selective agents at this level could increase selection efficiency. Two susceptible pistillate plants and one tolerant and one susceptible staminate plants were used in controlled crosses. Before pollination, a drop of a germination vehicle with TCF or without it was applied to the stigmas. Some pollinated pistils were fixed and analyzed by fluorescence microscopy; the rest were left on the plant for seed production. Fifty to 200 seeds were obtained per treatment combination (staminate plant x pistillate plant x pollination vehicle). The derived plantlets were inoculated in vitroand evaluated for disease symptoms. The application of TCF to stigmas reduced pollen germination and tube growth compared with untreated controls,regardless of the genotypic combination. Pollen germination and tube growth was poorer for the tolerant staminate genotype than for the susceptible one. When the TCF was applied, the number of seeds per pollination in comparison with the controls diminished only when the susceptible genotype was the pollinator. The percentage of affected root area of the progenies obtained after applying the TCF was lower than in the controls only when the tolerant genotype was the pollinator. Increasing Fusarium resistance in asparagus by means of gametophyte selection seems feasible. This revised version was published online in August 2006 with corrections to the Cover Date.     

Anatomic and volumetric characterization of the cisterna chyli using CT lymphangiography and computer‐assisted design software in dogs with idiopathic chylothorax

The objectives of this retrospective, observational study were to characterize the anatomical features of the cisterna chyli (CC) in a cohort of dogs diagnosed with idiopathic chylothorax that underwent CT lymphangiography (CTLa), and to evaluate the feasibility of computer‐assisted design (CAD) software to quantify volumetric measurements of the CC. Twenty‐three client‐owned dogs with idiopathic chylothorax were included. Additionally, CTLa was performed in three canine cadavers to assess the ability of CAD software to accurately acquire volumetric measurements. Injection sites, attenuation values, anatomic location, dimensions, and aortic diameter to CC ratio (Ao:CC) were recorded. Video records of video‐assisted thoracic surgery (VATS) thoracic duct ligation (TDL) were reviewed in eight out of 23 dogs to compare operative and CTLa findings. The CC was dorsal and right‐sided in 18 out of 23 dogs, located between L1 and L4 in 21 dogs, and extended as far cranially as T11 in two dogs. The median measurements for length, height, and width were 150.0, 5.5, and 13.3 mm, respectively. Median total volume was 1.82 mL. Median volumes to the right and left of the aorta were 1.46 and 0.49 mL, respectively (P = .014). Median total CC volume to body weight ratio (CC:bw) was 0.07 mL/kg. The presence of an intrathoracic CC was observed intraoperatively in six out of eight cases that underwent VATS TDL. Findings supported the use of CTLa and CAD as feasible methods for characterizing the CC in dogs diagnosed with chylothorax. These methods may facilitate interventional planning involving the CC such as embolization.