The influence of tropical adaptation on plasma concentrations of insulin-like growth factor-I in purebred and crossbred beef cattle

In an effort to determine whether tropical adaptation influences circulating concentrations of the growth-related hormone IGF-I, 3-breed diallel matings were conducted using temperate Bos taurus (Angus), tropical Bos indicus (Brahman), and tropical Bos taurus (Romosinuano). Purebred Angus, Braham, and Romosinuano and crossbred Angus-Braham, Angus-Romosinuano, and Braham-Romosinuano heifers and steers were evaluated in 2 separate calf crops from 2003 and 2004. Blood samples were obtained from 10 heifers of each breed group (n = 90) for each year at weaning and on d 0 and 84 of postweaning trials. Samples were also taken from 10 steers of each breed group (n = 90) at weaning and on d 0 and 60 of individual finishing phase feeding trials for each year. Concentrations of IGF-I were determined by RIA. Analyses included effects of sire breed, dam breed, year of record, the age of the dam of the calf in years, and interactions. Age of calf in days was investigated as a linear and quadratic covariate. Separate analyses were conducted for steers and heifers. The direct effect of Angus was to reduce (P < 0.03) heifer concentrations of IGF-I at d 84 and in the repeated measures analysis. In the repeated measures analysis, the direct effect of Romosinuano was to increase concentrations of IGF-I (P = 0.01). Relative to the temperate Bos taurus breed, plasma concentrations of IGF-I were numerically greater in male and female tropically adapted breed groups.     

Microtuber dormancy in three potato cultivars

Microtuber size, media growth regulators, incubation period, as well as bud maturity and endogenous abscisic acid content of microtubers were evaluated for their effects on length of dormant period of Kennebec, Russet Burbank and Superior microtubers. The dormant period of microtubers was found to be cultivar-specific and a significant correlation was observed betweenin vitro andin vivo dormant periods. Smaller microtubers (≤250 mg) had longer dormant periods than did those greater than 250 mg. Dormant periods were unaffected by addition of coumarin or 2-(chloroethyl)-trimethylammoniumchloride and 6-benzylaminopurine to the culture media or incubation period (28 and 56 days). Developmental age had no effect on individual buds ability to break dormancy and elongate. A positive correlation was observed between tissue levels of abscisic acid and microtuber dormant periods.     

Vaccination coverage and epidemiological parameters of the owned-dog population in Thungsong District, Thailand

Canine rabies vaccination is delivered in Thungsong District, Thailand, as an annual campaign between March 1 and 31, and also at other times through private veterinary clinics, para-veterinarians and health-care staff residing in the villages. The current questionnaire-interview survey was conducted between June 23 and July 18, 2002 to determine: rabies-vaccination coverage amongst the owned-dog population; basic dog-population information; and community awareness about rabies. The modified expand programme on immunization cluster-survey method was used to collect information about dog demography and management characteristics. Household knowledge about rabies and sources of rabies information were assessed. Vaccinated dogs were identified from vaccine certificates or owner reports confirmed by vaccinators. Seventy percent (95%CI 62-78) of 364 eligible owned dogs were vaccinated within the 6 months prior to data collection. Of these 255 vaccinated dogs, 44, 21, 13, 17 and 5% were vaccinated through the annual vaccination campaign, veterinary clinics, para-veterinarians, other vaccinators and owners, respectively. Fifty-four percent of households owned dogs. The sex ratio in dogs was 2 males per female; the dog: human ratio was 1: 4.6 with an average of 0.9 dogs per household (1.7 dogs per dog-owning household). Most dogs roamed freely and these were less likely to be vaccinated compared to dogs being kept on premises or on a leash. Almost all households were aware of rabies and the need for dog rabies vaccination as a control method. Seventy-six percent believed that rabies only occurred in summer. There was little awareness about cat rabies amongst households. Vaccination coverage in the total dog population clearly has not yet reached the 80% target level set by Thailand's official rabies-control programme. Improved effectiveness of the owned-dog rabies-vaccination campaigns in each community is needed-perhaps by more community education about dog management or by better management of ownerless dogs.     

Effects of dietary protein concentration on postweaning growth of Boer crossbred and Spanish goat wethers

Boer (3/4) x Spanish (1/4) (BC; n = 23) and Spanish (SP; n = 22) goat wethers, 4 to 4.5 mo of age and 17.6 and 19.4 kg initial BW, respectively (SE = 0.57), were used to determine effects on growth of protein concentration in 70% concentrate diets provided for ad libitum intake for 30 wk in confinement. Offered diets contained 10.2, 14.2, 18.3, and 23.6% CP (DM basis), and CP concentration in consumed DM was 9.3, 13.8, 17.1, and 22.1% (P1, P2, P3, and P4, respectively); supplemental protein was from soybean meal for P1 and P2 and from soybean meal plus a blend of blood, fish, and feather meals for P3 and P4. Dry matter intake was similar between breeds and among diets (732, 712, 698, and 740 g/d for P1, P2, P3, and P4, respectively; SE = 27.0). Average daily gain was greater for P2 (P = 0.07) and P4 (P < 0.05) than for P1 (76, 90, 85, and 100 g/d for P1, P2, P3, and P4, respectively; SE = 5.3) and for BC than for SP (97 vs 78 g/d, SE = 3.7; P = 0.05). Similarly, ADG:DMI was lowest (P < 0.05) among diets for P1 (0.106, 0.126, 0.121, and 0.132 for P1, P2, P3, and P4, respectively; SE = 0.0053) and greater (P < 0.05) for BC than for SP (0.135 vs 0.108; SE = 0.0037). In conclusion, with 70% concentrate diets, the protein requirement for both BC and SP seemed to have been met by consumption of diets with at least 14% CP, with no apparent benefit from addition of ruminally undegraded protein.     

Modification of potato microtuber dormancy during induction and growthin vitro orex vitro

Prolonged or highly variable dormancy can be a significant impediment to the efficient use of potato (Solanum tuberosum L.) microtubers by the seed industry. In the present study, reductions in microtuber dormancy duration were obtained in cultivars commonly used by the processing industry (Kennebec, Russet Burbank and Shepody). This was achieved by modifying microtuber induction media and applying various dormancy-release treatments after harvest, with or without prior storage. An 8 h photoperiod, instead of continuous darkness during microtuber induction and development, increased microtuber yield while reducing dormancy duration. Dormancy duration was also shortened by increased sucrose concentration during microtuber induction under an 8 h photoperiod. As sucrose was increased from 4 to 16% under an 8 h photoperiod, mean dormancy duration decreased by 86 d for Shepody, 65 d for Kennebec and 46 d for Russet Burbank. During theex vitro storage period, 24 h treatment with bromoethane vapor (from 0.22 ml liquid BE per L volume) or bromoethane vapor followed by a 3 d treatment of 60% CO₂/ 20% O₂/ 20% N₂ resulted in a rapid dormancy release of freshly harvested microtubers. These dormancy-releasing treatments significantly increased minituber yields under greenhouse conditions for all cultivars when compared to untreated controls. Increased minituber yields were also observed when dormancy release treatments were applied to microtubers after storage at 6 C for 8 weeks. The results demonstrate that microtuber dormancy duration can be manipulated during growthin vitro orex vitro. However, optimization may require cultivarspecific protocols     

Magnetic Field Signatures Near Galileo's Closest Approach to Gaspra

Two large magnetic field rotations were recorded by the spacecraft Galileo 1 minute before and 2 minutes after its closest approach to the asteroid Gaspra. The timing and the geometry of the field changes suggest a connection with Gaspra, and the events can be interpreted as the result of the draping of the solar wind field around a magnetospheric obstacle. Gaspra's surface field is inferred to be within an order of magnitude of Earth's surface field, and its magnetic moment per unit mass is in the range observed for iron meteorites and highly magnetized chondrites. The location of the magnetic signatures suggests that perturbations are carried by waves in the magnetosonic-whistler mode with wavelengths between electron and ion gyro radii.     

The chlorine isotope composition of Earth's mantle

Chlorine stable isotope compositions (delta37Cl) of 22 mid-ocean ridge basalts (MORBs) correlate with Cl content. The high-delta37Cl, Cl-rich basalts are highly contaminated by Cl-rich materials (seawater, brines, or altered rocks). The low-delta37Cl, Cl-poor basalts approach the composition of uncontaminated, mantle-derived magmas. Thus, most or all oceanic lavas are contaminated to some extent during their emplacement. MORB-source mantle has delta37Cl 相似文献