Field trials with a bivalent vaccine (HVT and SB-1) against Marek's disease

White leghorn chickens on five farms were given a bivalent Marek's disease (MD) vaccine consisting of turkey herpesvirus (HVT) and SB-1 (a nononcogenic MD virus); other chickens received only HVT. The farms had histories of "vaccination failures," presumably owing to an exceptionally virulent challenge MD virus. The bivalent vaccine uniformly protected chickens better than HVT alone between 12 and 16-20 weeks of age, when serious MD losses occurred. During that period, total mortality in groups given both viruses ranged from 0.39 to 1.26% (mean 0.86%), whereas that in HVT-vaccinated groups not exposed to SB-1 varied from 1.92 to 7.44% (mean 3.43%). Chickens in pens or rows with close contact to those given bivalent vaccine also had low MD mortality rates (0.46-1.06%, mean 0.77%), probably from the spread of SB-1.     

A note on the structure and iron‐binding properties of egg‐shell membranes

1. When a solution of ferric ammonium sulphate was added to shell membranes of the domestic fowl, iron infiltrated the mantle (cortex) surrounding the cores of the individual fibres of the membranes.

2. Contraction of warm eggs in ice‐cold colloidal iron caused flooding of pore canals and contamination of the underlying shell membranes with this element.

3. Appreciable contamination of the inner shell membrane with iron persisted for 25 d in infertile eggs stored at 37.5 °C.     

Depression of polymorphonuclear leukocyte function associated with experimentally induced Escherichia coli mastitis in sows

In a study of susceptibilities of sows from 2 herds to experimentally induced Escherichia coli mastitis, a marked difference was seen. The "susceptible" sows were from a conventional herd and "resistant" sows were from a specific-pathogen-free herd. The purpose of the study was to determine whether deficient neutrophil function was associated with increased susceptibility to E coli-induced mastitis. Four in vitro procedures were used to evaluate polymorphonuclear leukocyte (PMN) function: (i) random migration under agarose, (ii) ingestion of 125I-iododeoxyuridine-labeled Staphylococcus aureus, (iii) quantitative nitroblue tetrazolium reduction, and (iv) iodination. After parturition and intramammary inoculation with E coli, sows from the susceptible herd were neutropenic and the neutrophils which were present in the peripheral blood had reduced function. Specifically, there were depressed random migration under agarose, S aureus ingestion, and iodination when compared with PMN function in resistant sows. These data indicate that susceptibility to E coli mastitis was associated with deficiencies in PMN numbers and function. Potential causes of the neutrophil dysfunction are discussed and include possible systemic hormonal aberrations or the presence of an inapparent viral or bacterial infection.     

A 31P topical magnetic resonance study of embryonic development in hens' eggs

1. A ³¹P topical magnetic resonance study of whole chicken's eggs in vivo is described.

2. Resonances from adenosine triphosphate, phosphocreatine, inorganic phosphate and phosphorous storage protein were observed. These changed in relative intensity as the embryo developed.

3. No ill effects due to exposure to radiofrequency radiation or magnetic fields were observed.

4. It is concluded that topical magnetic resonance can make a useful contribution to the study of embryonic development in avian eggs.     

A note on changes in egg‐shell porosity with flock age and season during the first breeding cycle of domestic ducks

1. — Changes in egg weight and egg‐shell porosity with flock age and season are presented for domestic duck flocks in their first laying cycle.

2. — The first eggs laid are of low weight and shell porosity but generally by the fifth week of lay both characteristics have increased to the values found in the mature flock.

3. —For mature flocks porosity decreases in the summer and the consequences of this are considered in relation to the observed decrease in hatch‐ability at this time.     

Effects of lauryl sulphate on egg‐shell quality in laying hens

1. The effect of feeding the detergent, sodium lauryl sulphate at concentrations up to 10 g/kg diet on egg‐shell quality was examined in laying hens at 24, 36 and 48 weeks of age.

2. Lauryl sulphate at 2.5 g/kg or more in the diet significantly increased shell breaking strength, shell thickness and shell weight at 24 and 36 weeks. In 48‐week‐old hens only shell breaking strength was increased significantly. Egg production and egg weight were not affected significantly by lauryl sulphate.

3. Lauryl sulphate might increase these measures of quality by increasing shell deposition and/or shell elasticity.     

Small intestinal carcinoma in cattle

The pathology of carcinoma of the small intestine in six adult cattle is described. The lesions were similar to those of carcinoma of the small intestine of sheep although a slightly less fibrous stroma and a greater tendency to metastasise was observed. Initial findings suggest the disease resembles small-intestinal carcinoma of sheep and cola-rectal carcinomas of man in having a higher prevalence in New Zealand than most other countries. This highlights the need to investigate common environmental factors which may be responsible for the induction and promotion of these tumours in both grazing ruminants and man.     

Reproductive efficiency of heifers in the new guinea highlands

Summary Bos indicus × Bos taurus heifers were exposed to bulls at four different liveweights. The age and weight at first and second conception and first calf growth rates were studied to examine the effects of uncontrolled mating prior to or at a target mating weight of 295 kg. Initial conception rate was not affected although lighter conception weights were recorded for three groups of heifers that were served when below the target weight. However, at subsequent calving only the two heavier groups calved within the 36-month trial period. The results indicated a seasonal effect on conception, 94% of the heifers conceiving during the wet season. The effect of season also influenced post-partum body weight loss, calf growth rate to weaning and subsequent conception. It is therefore an advantage to have heifers conceiving during the latter part of the wet season so that they calve early in the following wet season, provided a minimum target weight of 285 kg is reached prior to initial conception.

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Eficiencia Reproductiva De Terneras En La Sierra De Nueva Guinea

Resumen Se cruzaron ternerasBos indicus ×Bos taurus de diferentes pesos con toros reproductores. Se estudiáron así los pesos y edades a la primera y segunda parición y las tasas de crecimiento de los recién nacidos, para medir los efectos de cruzamientos incontrolados versus controlados al alcanzar las hembras un peso de 295 kg. La tasa de concepción inicial no se afectó, aunque los recién nacidos de los grupos de hembras servidas cuando tenían pesos inferiores a 295 kg, pesaron menos. Sinembargo en pariciones sucesivas, solamente las hembras servidas con pesos de 295 kg, parieron en el lapso de 36 meses que duró el experimento. Los resultados indicaron también, que la estación del año afectó las pariciones, el 94% de las hembras concibieron durante la época lluviosa. La época del año también afectó el peso posparto de los recién nacidos, la tasa de crecimiento hasta el destete y las concepciones posteriores. Es por lo tanto ventajoso cruzar las hembras durante el final de la estación lluviosa para que paran en la siguiente estación lluviosa, procurando que éstas alcancen un peso mínimo de 285 kg, antes del apareamiento.

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Efficacite Reproductrice Des Genisses Des Hautes Terres De Nouvelle Guinee

Résumé Des génisses métissesBos indicus ×Bos taurus ont été mises en présence de taureaux à 4 poids vifs différents. L'age et le poids à la première et la seconde conception ainsi que les taux de croissance du premier veau ont été étudiés pour déterminer les effets l'accouplement incontrôlé avant ou à un poids cible d'accouplement de 295 kg. Le taux initial de conception n'a pas été affecté bien que des poids plus faibles à la conception aient été observés chez trois groupes de génisses qui étaient en dessous du poids cible au moment de la saillie. Cependant, lors du vêlàge suivant, seuls les deux groupes les plus lourds ont mis bas pendant la période d'observation de 36 mois. Les résultats montrent que la saison a une influence sur la conception. 94 p. 100 des génisses conçoivent pendant la saison des pluies. La saison a aussi influencé la perte de poids après la mise-bas, le taux de croissance des veaux jusqu'au sevrage et la conception suivante. Il est donc avantageux de faire féconder les génisses pendant la seconde moitié de la saison des pluies afin qu'elles mettent bas au début de la saison des pluies suivante pourvu qu'un poids cible minimum de 285 kg soit atteint avant la fécondation.

     

Equine herpesvirus abortion in Australia 1977 to 1982

Until 1977 no case of abortion caused by equine herpesvirus 1 (EHV1) had been recorded in Australia although the virus, called equine rhinopneumonitis virus, had been known to have been present at least since 1962. Outbreaks of EHV1 abortion occurred in New South Wales in 1977 and in 1981. Sporadic cases of EHV1 abortion had been confirmed in some parts of Australia each year since 1975. It was concluded that an abortigenic subtype of EHV1 had been introduced to Australia in 1977 and that the previously endemic respiratory subtype occasionally caused abortion. Virus isolation in a variety of cell cultures and histopathological examination of tissue were shown to be satisfactory methods of diagnosis of EHV1 abortion. Lung proved to be the specimen of choice. Slight serological differences between "abortigenic" and "respiratory" subtypes of EHV1 were found in cross neutralisation tests. A serological survey of 219 Sydney horses of various ages revealed that most yearlings had already acquired neutralising antibody to both subtypes.