Isolation and identification of a bovine adenovirus type 3 with an adenovirus-associated virus.

A bovine adenovirus with agglutinating activity was isolated from feedlot calves and classified as serotype 3. The agglutinating activity was shown to be the property of an adenovirus-associated virus (AAV). The AAV was isolated from the bovine adenovirus by isopycnic centrifugation in CsCl; the AAV had a density of 1.4 g/cm2. This AAV is serologically related to bovine AAV-TR-15, but is distinct from bovine parvovirus-1 and primate AAV types 1 to 4, using counterimmunoelectrophoresis and hemagglutination-inhibition.     

Indirect solid-phase microradioimmunoassay for detection of pseudorabies virus antibody in swine sera.

An indirect solid-phase microradioimmunoassay (IRIA) was developed for detection and quantitation of antibodies to pseudorabies virus (PRV) in swine serum. Qualitative results of the IRIA compared closely with results of the serum neutralization test (NT) and the microimmunodiffusion test (MIDT). The IRIA was more sensitive than the NT for detection of antibodies to PRV in swine serum. The IRIA result is expressed numerically. With the IRIA and NT, antibody to PRV was first detectable in 3 experimentally infected pigs at 9 days after inoculation. With MIDT, antibody was detected in the 3 experimentally infected pigs at 9 days after inoculation. With the MIDT, antibody was detected in the 3 experimentally infected pigs at 7, 8, and 9 days after inoculation. The IRIA results are obtainable within a few hours; the NT and MIDT require 48 hours for completion.     

Lumbar spondylectomy in the subhuman primate.

Removal of the 2nd or 3rd lumbar vertebrae (or both) has been accomplished in the subhuman primate (Macaca mulatta). Variations between this animal and the dog in posture, vertebral column anatomy, and spinal cord blood supply made no apparent difference in the results when compared with those in previous experiments. All macaques were able to clinb and to use their hind legs in a normal manner within 3 days after surgical operation. Once hair had regrown over the surgical incision, persons not familiar with the animals were not able to identify the animals that had undergone surgical operation. If a single vertebra was removed, use of spinous process and a single vertebral body plate was sufficient to stabilize the vertebral column. Except for 1 rhesus macaque whose spinous process plates were removed 20 days after the operation, vertebral columns of macaques (n = 3) that underwent single spondylectomy healed in nearly normal alignment. With the removal of 2 lumbar vertebrae, the previously described stabilization procedure was not sufficient to prevent kyphotic deformity of the vertebral column. Spinous process plates from 1 macaque were removed after 64 days. However, all these macaques (n = 3) could climb and use their legs as well as others in the colony.     

The use of air‐coolers in broiler houses under subtropical conditions in Iraq

1. Under summer conditions in north Iraq, 2 000 chicks were reared for 56 d in two broiler houses. One house was provided with two air‐coolers. The birds were housed at densities of eight to 16 birds/m².

2. Differences in weight gain between birds in cooled and uncooled houses ranged from 101.5 g at eight birds/m² to 385 g at 16 birds/m². Food consumption increased gradually with increasing bird density. Food conversion efficiency, meat yield and carcass conformation were much better in the cooled house than under conventional conditions.

3. The financial return/m² ranged from 2.30 to 4.51 ID¹ in the cooled house, compared with 2.01 to 2.77 ID in the uncooled house at different floor densities.     

Sire × hatch interaction effects and pen effects in progeny testing broiler males for growth rate

1. Pen effects and sire x hatch interaction effects on growth rate to 8 weeks of age were estimated from family and progeny test data obtained from the application of two commercial breeding programmes for growth rate to broilers.

2. The following variance components were obtained: σ²(pen) = 255 g², σ²(sire) = 1 260 g², σ²(sire × hatch) = 1 997 g²,σ²(residual) = 19 708 g².

3. It is concluded that the effectiveness of progeny testing for growth rate in broilers is severely restricted by sire x hatch interaction effects.     

An investigation into the basic virus-antibody neutralization reaction, with special regard to the reaction in the constant-virus/varying-serum neutralization test.

A study of the basic reaction in neutralization of virus (V) by virus-neutralizing antibody (VNA) was performed with infectious bovine rhinotracheitis virus and serum collected from naturally and experimentally infected cattle after the primary immunization phase. In constant-virus/varying-serum neutralization tests a direct proportionality between VNA titer and length of preincubation was observed and found to be in accordance with basic laws of neutralization. A deviation from this direct proportionality, which was partly attributed to the presence of a dissociable V-VNA complex, was seen with relatively short preincubation. Expressing a relationship between VNA titer, length of preincubation, and virus dose under conditions where a dissociable V-VNA complex can be ignored, a log. VNA/log. V equivalence factor of neutralization was introduced. A linear relationship was found between VNA titer, taken logarithmically, and preincubation temperature. A rise in temperature by 10°C gave an increase in VNA titer of approx. 1.2 in log₂. Formulae are presented for the neutralization rate factor corrected for a demonstrated invalidity of the percentage law, and for the relation between the neutralization rate factor and VNA titer. It is concluded that the results presented have elucidated the possibilities of improving the sensitivity of neutralization tests.