Influence of dietary protein and sex on walking ability and bone parameters of broilers

1. The study was conducted to investigate the effect of dietary protein on the walking ability and bone parameters of broilers reared under summer temperatures which ranged from 26 to 32C(+/-2C). 2. Three different dietary protein combinations were used. The diets (per kg) were: low protein with 205 g crude protein and 12.94 MJ ME, 184 g crude protein and 12.75 MJ ME; medium protein with 219 g crude protein and 12.99 MJ ME, 201 g crude protein and 12.87 MJ ME; and high protein with 238 g crude protein and 12.99 MJ ME, 216 g crude protein and 12.96 MJ ME from 0 to 4 and 4 to 7 weeks of age, respectively. Body weights of birds were recorded and birds' walking ability (gait scoring) were scored for each bird, according to 3 categories (completely normal to immobile, at 4 and 7 weeks). Tibia parameters and tibia plateau angles were also determined at 7 weeks. 3. Birds fed on the low protein were lighter than those fed on the medium or high protein diets. At 7 weeks, birds with poor walking ability weighed 149 g less than birds with no walking difficulty. 4. Bone parameters were not affected by dietary protein, sex or gait score. There was a significantly positive correlation between bone strength and radiographic density. Bone strength was also significantly correlated with bone weight and length.     

Pathogenesis of Trypanosoma (brucei) evansi in small East African goats

Trypanosoma evansi is the cause of surra, a camel disease which is the most important single cause of economic losses in camel rearing areas. Sheep and goats herded with camels are the most likely hosts for T evansi. Upon intravenous infections goats developed erratic parasitaemia, lost weight and their packed cell volume dropped significantly (P<0–001). Trypanosomes were demonstrated by direct microscopy in extravascular locations such as synovial, peritoneal and cerebrospinal fluids and also in lymph by subinoculations into mice. The carcases were emaciated and pale. Histologically there was lymphatic tissue hyperplasia, muscular atrophy and nephrotic changes. Two animals had necrotic foci in the liver, kidneys, lymph nodes, spleen and lungs and also bronchopneumonia. Histologically there was depopulation of lymphocytes in lymphatic tissues, destruction of hepatocytes in the liver with infiltration by inflammatory cells in the liver, lymph nodes, spleen and the kidneys.     

Pathogenesis of BSE

Before the emergence of bovine spongiform encephalopathy (BSE) and recognition of its zoonotic potential, the major example of the transmissible spongiform encephalopathies (TSEs) of animals was scrapie of sheep. But there is no evidence that scrapie transmits naturally to any species other than sheep and goats. The pathogenesis of scrapie has been studied most in experimental laboratory rodent species. In most experimental models of scrapie, after peripheral non-neural routes of infection, replication of the agent can first be detected in lymphoreticular system (LRS) tissue. When the route of introduction of agent into the body is localized, initial involvement will be in LRS tissue draining the infection site. Thereafter, there is a striking amplification of the agent in the LRS and spread by lymphatic/haematogenous routes, giving widespread dissemination in the LRS. This precedes replication in the CNS, but is not the means by which infection reaches the CNS. There is now substantial evidence from experimental models of scrapie that involvement of the CNS is by peripheral nervous system (PNS) pathways. In some models employing oral exposure the earliest localized LRS replication is in the gut-associated lymphoid tissue (GALT) and autonomic PNS routing to the CNS has been implicated. However, the relative importance of different routes of spread of TSEs within the body is determined by a number of host- and agent-dependent factors and, therefore, generalizations from an experimental model to a natural disease across a species barrier may not be appropriate. With the occurrence of BSE and recognition of its food-borne route of transmission via meat and bone meal, has come greater awareness of the probable importance of the oral route of infection in ruminant species affected by TSEs. In consequence, studies have increasingly focused on the natural host species to examine pathogenetic events.     

Serotyping and virulence genes detection in Escherichia coli isolated from fertile and infertile eggs, dead-in-shell embryos, and chickens with yolk sac infection

Escherichia coli is a common avian pathogen mainly associated with extraintestinal infections such as yolk sac infection (YSI). The aim of this study was to determine the serotypes and the presence of some virulence genes of E. coli strains isolated from different samples in a vertically integrated poultry operation in Mexico. Two hundred sixty-seven E. coli isolates from different samples were serotyped using rabbit serum against the 175 somatic (O) and 56 flagellar (H) antigens of the typing schema. Virulence genes were determined by colony blot hybridization, using DNA probes for st, eae, agg1, agg2, bfp, lt, cdt, slt, and ipaH diarrhea-associated virulence factors. The serogroup of 85% of the strains was determined; O19 (12%), 084 (9%), 08 (6%), and 078 (5%) were the most common. Using the complete antigenic formula (O and H), O19:NM (n = 31) was the serotype most frequently isolated from dead-in-shell embryos and in broilers that had died on the fourth, fifth, sixth, and seventh days after hatch. One hundred ten strains (41.2%) hybridized with one or more of the used probes. Of these, ipaH (72%), eae (30%), and cdt (27%) were the most common. Considering the origin of the respective isolates, 40% of the broiler farm strains were positive for at least one probe. Results show that some avian E. coli strains isolated in Mexico are included in avian pathogenic E. coli serotypes not previously reported, suggesting that they could be specific for this geographic area. The wide distribution of the ipaH gene among nonmotile strains suggests that this invasiveness trait could be important in YSI pathogenesis. On the other hand, some other genes could contribute to E. coli virulence during YSI.     

Hyperextension of fetlock joints in German Holstein and German Holstein-Limousin crossbred calves

In two different dairy farms six calves exhibiting bilateral flexion of the fetlock joints in front or rear legs were born in 2000 to 2002. Four of the affected calves from the same farm were crossbred between German Holstein cows with red and white coat colour and a bull of the breed Limousin. The other two affected calves born on another farm were purebred German Holsteins with a black and white coat colour. The tests for BVD virus antigen and antibodies were negative in all affected calves. Three of the calves showed a lower selen and a higher glutamate dehydrogenase concentration in the analyses of blood metabolites. Two crossbred calves showed a degeneration of the liver with a progressive periportal fibrosis in a histological examination. In one calf an edema of astrocytes of the central nervous system was seen. The analysis of the pedigrees revealed for the four crossbred calves the Limousin bull as common ancestor and the mothers of the calves as relatives. For the affected purebred German Holstein calves also a sire was identified as a common ancestor. The pedigrees support inheritance through a monogenic autosomal recessive locus or more recessive gene loci with variable expressivity. However, the analysis could not clarify whether different gene loci are responsible for the congenital anomalies observed in the calves from the two farms and thus, the observed anomalies may be different genetic entities. Obvious environmental reasons were not found.     

Repeat tuberculin skin testing leads to desensitisation in naturally infected tuberculous cattle which is associated with elevated interleukin-10 and decreased interleukin-1 beta responses

The principal surveillance tool used to control bovine tuberculosis in cattle is the removal of animals that provide a positive response to the tuberculin skin-test. In this study we performed a longitudinal investigation of the immunological and diagnostic consequences of repeated short-interval skin-tests in cattle naturally infected with Mycobacterium bovis. Tuberculin skin-test positive cattle were subjected to up to four further intradermal comparative cervical skin-tests at approximately 60-day intervals. A significant progressive reduction in the strength of the skin-test was observed after successive tests. In contrast, the magnitude of interferon-γ (IFN-γ) responses was not influenced by repeat skin-testing either transiently around the time of each skin-test or longitudinally following repeated tests. A significant boost in blood interleukin-10 (IL-10) production was observed within 3 days following each skin-test although the magnitude of this boosted response returned to lower levels by day 10 post-test. The application of a novel multiplex assay to simultaneously measure seven cytokines and chemokines also identified that skin-testing resulted in a significant and progressive reduction in antigen specific interleukin-1β (IL-1β) whilst confirming stable IFN-γ and elevated IL-10 responses in the blood. Therefore, we have demonstrated that in cattle naturally infected with M. bovis, repeat short-interval skin-testing can lead to a progressive reduction in skin-test responsiveness which has potential negative consequences for the detection of infected animals with marginal or inconclusive skin-test responses. The desensitising effect is associated with decreased IL-1β and elevated IL-10 responses, but importantly, does not influence antigen specific IFN-γ responses.     

Die Bekämpfung des Kartoffelkäfers (Leptinotarsa decemlineata Say)

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