Detection of Actinobacillus pleuropneumoniae Infection in Pigs

It is difficult to control the spread of porcine haemophilus pleuropneumonia caused by Actinobacillus pleuropneumoniae because there is no sensitive and specific way to accurately determine whether or not a pig herd is infected. This paper reports bacteriological and serological techniques used to detect A. pleuropneumoniae infection in pigs from a herd with endemic disease.

The bacteria were isolated from the anterior nasal mucosa of grower pigs, but not from younger or older pigs. Bacteriological culture of several tissues from the respiratory tract showed that nine of ten young finishing pigs were infected, but culture of lung tissue from slaughtered hogs detected infection in only 39 of 288 (13.5%). Both cooler storage temperature and use of selective medium prolonged the time that lung tissue could be stored and the organism still recovered. An enzyme-linked immunosorbent assay detected serotype-specific antibodies in serum of infected pigs.

     

A modified technique for flushing ova from the sheep uterus

Abstract

Extract

Sheep ova are normally obtained from the reproductive tract using the flushing techniques described by Hunter et al. (1955) Cumming, I. A. and McDonald, M. F. 1967. The production of ova by New Zealand Romney ewes following hormonal stimulation. N.Z. Jl agric. Res., 10: 226–236. [Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]. Oviduct flushes, in the writers' experience, give a higher recovery of ova than uterine flushes, but they result in more adhesions of the tract, which can cause infertility. Consequently, the development of satisfactory uterine flushing techniques appears necessary before ova can be recovered repeatedly from superior ewes. This paper describes such a technique.     

Carbon kinetics of milk formation in Holstein cows in late lactation

Carbon transfer to milk in Holstein cows in late lactation was measured by introducing changes in the natural stable carbon isotope composition of the feed. Six Holstein cows in mid-lactation were placed on a diet naturally low in 13C (-25.0% vs Pee Dee belemnite [PDB] an international carbon isotope standard), based on alfalfa-barley, and six others were placed on a diet naturally enriched in 13C (-11.5% vs PDB), based on corn. After a 7-wk equilibration period on these diets, three cows were switched from alfalfa-barley to corn, and three were switched from corn to alfalfa-barley. The three other cows in each group served as controls. 13C/12C ratios were measured in daily morning milk samples during the week before and for 6 wk after the changes in diet. After the diets had been switched, milk isotope ratios rapidly approached the isotopic composition of the new diet, indicating rapid transfer of dietary carbon into milk. The data were consistent with a model whereby milk was synthesized from a single precursor pool that responded rapidly to dietary perturbation. The milk precursor pool had a half-life of approximately .9 d and had a mass of approximately 7 kg of carbon, which was renewed daily by the entry of 5 kg of digestible dietary carbon.     

Spatial and temporal analysis of coffee wilt disease caused by Fusarium xylarioides in Coffea canephora

Coffee wilt disease (CWD) caused by Fusarium xylarioides, considered to be a soil-inhabiting fungus, is endemic in several African countries, affecting commercially important coffee species and causing serious economic losses. Coffee wilt disease development in naturally infected Coffea canephora fields at the Coffee Research Institute in Uganda was assessed from April 2001 to March 2006 to generate information about temporal and spatial spread of the disease. Maps of diseased trees were also generated from the data. Semi-variance analysis was performed on the data to show the spatio-temporal structure of disease. Host influence on the spatio-temporal structure was deduced from the distribution pattern of diseased and healthy trees and analysis of variance. Results show that the temporal disease epidemic progress was slow. The disease was found to spread from initial infections to healthy neighbouring trees, resulting in an aggregated pattern. An infected tree could infect up to three healthy trees away, in any direction. Disease foci formed and expanded with time, coalescing but punctuated in spots planted with resistant hosts. There were varying levels of susceptibility among host genotypes, affecting the rates and levels of epidemic development. The implications of the findings to the control of CWD are discussed.     

Effect of reducing dietary mineral content on growth performance, water intake, excreta dry matter content and blood parameters of broilers

1. The objective of this study was to investigate whether it is possible to reduce phosphorus (P) excretion by feeding a lower level of dietary P than that currently recommended, without compromising welfare, and whether this is sensitive to the level of dietary calcium (Ca). 2. A randomised complete block design was used with a total of 224 1-d-old male chicks of a commercial genotype in two batches. Chicks had a 10-d adaptation period. After this, they were moved to cages and allocated to one of 4 dietary treatments (4 and 3 birds per cage in batch 1 and 2, respectively). A standard level of Ca and P (8.3 and 6.6 g/kg, respectively) was compared with three lower levels of Ca (7.3, 6.3 and 5.3 g/kg) all at the same reduced level of P (5.5 g/kg). Records were made of live weight of birds on an individual basis and feed and water consumption on a cage basis. Every 7 d, the dry matter (DM) content of a sample of mixed excreta from each cage was measured. Birds were slaughtered and samples taken for analysis of plasma mineral content, retention of N, Ca and P and tibia bone strength. 3. The initial reduction in dietary mineral level did not adversely affect performance or bone strength. However, decreasing dietary Ca level below 7.3 g/kg, at constant P, led to reduced feed consumption and bone strength. Dietary treatment had no significant overall effect on water intake, water : feed ratio, excreta DM content, Ca and P retention or metabolisability of DM. There was no significant correlation between mean plasma Ca or P level and DM content of rectal digesta. 4. In conclusion, reducing dietary P from 6.6 to 5.5 g/kg to reduce potential environmental impact of broiler production had an adverse effect on bird welfare when the level of Ca was reduced below 7.3 g/kg, as a result of decreased feed intake in the early growth period and reduced skeletal strength.