Prevalence of bovine viral diarrhea virus (BVDV) in persistently infected cattle and BVDV subtypes in affected cattle in beef herds in south central United States

The prevalence of bovine viral diarrhea virus (BVDV) in persistently infected (PI) cattle in beef breeding herds was determined using 30 herds with 4530 calves. The samples were collected by ear notches and tested for BVDV antigens using immunohistochemistry (IHC) and antigen capture enzyme-linked immunosorbent assay (ACE). Animals with initial positives on both IHC and ACE were sampled again using both tests and serums were collected for viral propagation and sequencing of a viral genomic region, 5′-untranslated region (5′-UTR) for viral subtyping. Samples were also collected from the dams of PI calves. There were 25 PI calves from 4530 samples (0.55%) and these PI calves were from 5 of the 30 herds (16.7%). Two herds had multiple PI calves and 3 herds had only 1 PI calf. Only 1 of the 25 dams with a PI calf was also PI (4.0%). The subtype of all the PI isolates was BVDV1b. Histories of the ranches indicated 23 out of 30 had herd additions of untested breeding females. Twenty-four of the 30 herds had adult cowherd vaccinations against BVDV, primarily using killed BVDV vaccines at pregnancy examination.     

More than a ‘blip’: The changed character of South‐East Asia’s engagement with the global economy in the post‐1997 period

Abstract: Through reviewing South‐East Asia’s recent economic engagement with the global economy, this paper points to profound recent transformations in the scope and character of the region’s development. Foreign direct investment was the key driver of regional growth in the pre‐1997 period, yet currently, the region faces a more difficult and multifaceted economic arena from which to attract such funds. Foreign direct investment is more selective, both geographically and by sector, than was the case in that earlier period. This paper explains the confluence of economics, business practices and politics that are giving rise to these outcomes, and concludes from this that development trajectories in South‐East Asia will become more diverse between the countries of the region, with implications for how we understand regional economic performance.     

Effect of Reduction of Supplementary Dietary Vitamins on the Stress Response of Channel Catfish lctalurus punctutus

Abstract— The influence of reduced amounts of supplemental vitamins on the stress response of channel catfish lctalurus punctatus was determined. Fish were fed diets with reduced levels of supplemental vitamin C, niacin, riboflavin, pantothenic acid, pyridoxine or thiamine, or with reduced amounts of the total vitamin supplement typically added to catfish feed. Fish were confined for 6 h and blood samples taken at 0, 1 and 6 h of confinement and 12 h after release. Plasma chloride and osmotic pressure were consistently stable throughout the experiment and were not influenced by the diet or the stress imposed. Cortisol concentrations were elevated at 1 and 6 h of confinement but recovered to preconfinement concentrations 12 h after release. The cortisol response varied in some of the groups; however, no consistent effects due to the vitamin concentrations were observed. The lack of supplemental vitamins in the food did not impair the ability of the fish to mount or maintain cortisol secretion. The feed ingredients may contain enough vitamins to support cortisol synthesis or the fish may be acquiring sufficient additional vitamins from the pond environment or from intestinal bacteria.     

Waste excretion characteristics of Manila clams (Tapes philippinarum) under different temperature conditions

Water recirculating systems have been used in the shellfish industry for depuration and wet-storage. Knowledge of shellfish excretion characteristics is critical to recirculating system design. In this study, the excretion rate of total ammonia nitrogen (TAN), total Kjeldahl nitrogen (TKN), and 5-day biochemical oxygen demand (BOD₅) from Manila clams (Tapes philippinarum) were investigated under both laboratory and commercial conditions. The laboratory tests were conducted under temperatures ranging from 3 to 30°C. The experimental results showed that temperature was a key factor in determining the excretion rate of all the above parameters. The relationship between TAN excretion rate (R_TAN) and temperature (T) can be represented by an exponential function (R_TAN=0.57×1.25^T). For the temperature range between 3 and 20°C, the daily mean excretion rates of TAN, TKN and BOD₅ ranged between 1.5–46.1, 4.8–131.0 and 57.4–219.4 mg per kilogram of the clams (wet weight with shell on), respectively. There were linear correlations between TAN, TKN and BOD₅ production rates. The data presented in this paper can be used to estimate waste generation from a given shellfish processing operation and to size the waste treatment components for a recirculating depuration (or wet-storage) system.     

蛋鸡非停喂强制换羽方法比较

历史上,商品蛋鸡行业所采用的大多数诱导换羽方案都有一个停喂饲料的阶段。停喂时间通常持续4～10d,但是在某些情况下停喂会一直延续至蛋鸡体重下降到目标体重为止。     

A review of genetic aspects of survival and resistance to cold in newborn lambsAspects génétiques de la survie et de la résistance au froid de agneaux nouveauc-nésGenetische Aspekte de überlebens und de Käteresistenz bei neugeborenenLämmern

Lamb mortality on British farms can vary from below 5% to over 40%. Severe weather (cold, wet or wind) is an important cause of death but its impact is extremely variable and sporadic. Its effectiveness in discriminating between lambs of different potential viability is therefore limited.Laboratory tests are now being used to measure the ability of lambs to resist cold exposure (i.e., prevent body cooling) and to identify the genetic and physiological factors involved. These include birthcoat type, birthweight, skin thickness, and metabolic rate responses. There are significant breed differences in cold-resistance tests, ability to resist hypothermia in the field, neonatal behaviour, and natural mortality rates in the field.Genetic selection for cold resistance, using a water-bath test, has recently commenced. The heritability of cold resistance and correlated responses in, for example, metabolic rate and lamb viability in the field, are being measured.     

Selective medium for isolation of Haemophilus somnus from cattle and sheep

Incorporation of vancomycin (5 micrograms/ml), neomycin (5 micrograms/ml), sodium azide (50 micrograms/ml), nystatin (100 iu/ml) and cyclohexamide (100 micrograms/ml) into 5 per cent horse blood agar results in a selective medium for the primary isolation of Haemophilus somnus from cattle and sheep. Addition of thiamine monophosphate (1 microgram/ml) to the medium enhanced growth of this bacterium. Gram-positive bacteria did not grow on the medium and colonies of many Gram-negative bacteria were eliminated or reduced in numbers and size. Colonies of H somnus were larger on the selective medium than on sheep blood agar but retained typical morphology. Recovery of 18 laboratory strains was 73 to 166 per cent (mean 112) on selective medium compared to sheep blood agar. H somnus was isolated from the vagina of a total of 136 (28.6 per cent) of 476 cows surveyed, 79 (16.6 per cent) on sheep blood agar and 129 (27.1 per cent) on selective medium. The selective agents and thiamine were stable indefinitely as a freeze dried mixture while prepared plates were stable for two weeks.