The effect of level of nutrition on the development of resistance to Haemonchus contortus in sheep

Merino wether weaners, 5-months old at the start of the experiment and fed lucerne-based pellets at 600 g per head per day, developed resistance to Haemonchus contortus given as a continuous or "trickle" infection at the rate of 500 larvae 3 times per week over a period of 17 weeks. By contrast, the development of resistance was impaired in weaners fed pellets at 400 g per head per day. Low food intake and protein-energy deprivation, therefore, have a major effect in impairing the development and expression of host-protective immunity against haemonchosis. The point at which low food intake causes outbreaks of haemonchosis in sheep at pasture is critical in determining procedures for prevention and control of the disease.     

Changes in the plasma concentrations of prolactin,luteinising hormone,progesterone and d‐(β)‐hydroxybutyrate in turkey hens (meleagris gallopavo), during treatment of broodiness under commercial conditions

1. An experiment was done under commercial conditions to investigate the physiological effects of isolating broody turkey hens, for 72 h, in sand and wire floored pens on the third, 10th and 16th weeks of production.

2. Hens identified as broody and removed from the flock had higher plasma prolactin concentrations than the laying hens at each of the three experimental stages.

3. Confinement in sand and wire floored pens, induced a decline in plasma prolactin concentrations. This decline probably impeded immediate development of broody behaviour. Alternately, levels of prolactin higher than those of laying hens were again measured 7 and 14 days after treatment during third week but not after the 10 th and 16th week of production.

4. Confinement did not induce consistent changes in luteinising hormone (LH) and progesterone concentrations from one period to an other.

5. An increase in the plasma concentration of D‐(/?)‐hydroxybutyrate was observed in the hens which had an egg present in the oviduct on day 2, 3 and/or 4 of the treatment. Subsequently, a decrease in ovulation rate was observed in the hens with higher concentrations of D‐(β)‐hydroxybutyrate while under treatment, during the 10th week of production.

6. These data confirm that the effectiveness of the traditional methods for broodiness prevention under commercial conditions is related to the induction of a decrease of prolactin.     

Ectopic ureter in the horse: Three cases and a review of the literature

Ureterovesicular anastomosis resulted in resolution of the clinical signs of urinary incontinence in three horses with unilateral ectopic ureter. Follow-up of two of the horses ten months and three years later indicated no further urinary tract problems; the third horse died four days after surgery from intestinal infarction.

Diagnosis can be readily confirmed by antegrade or retrograde ureterography, or endoscopic visualization of the ectopic ureteral openings. Nephrectomy appears indicated in cases of unilateral ectopic ureter with associated ipsilateral urinary tract infection or hydronephrosis, providing the contralateral kidney has normal function. Ureterovesicular anastomosis appears to be indicated in the management of unilateral ectopic ureters in the absence of ascending urinary tract infection or hydronephrosis, and in cases of bilateral ectopic ureters.

     

Influence of the sex-linked dwarfing gene (dw) on the contribution of dietary lipid to yolk lipid synthesis

1. The efficiency and time course of dietary fatty acid incorporation into lipids of egg yolk and abdominal adipose tissue was compared in "White Leghorn", normal (Dw) and dwarf (dw) laying hens at 56 weeks of age, using 14C labelled linoleic acid. 2. The sex-linked dwarfing gene, dw, was shown to reduce not only body weight and abdominal fat pad deposition, but also yolk production and the average clutch size. 3. Higher peak incorporation and total recovery of the linoleic acid radioactivity into yolk lipids, but lower label recovery into adipose tissue triglycerides were found in dwarf hens. 4. The higher esterification of the dietary linoleic acid in its native form into dwarf yolk triglycerides indicates that dwarf hens use more dietary lipids to synthesise yolk lipids but these results also suggest that the dw allele might reduce the lipogenic capacities of the liver and adipose tissue in laying hens.     

Five field trials on the efficacy of a bovine respiratory syncytial virus vaccine

Five field trials evaluated whether immunization of beef cattle prior to weaning, at weaning, or immediately upon arrival at the feedlot with a commercial bovine respiratory syncytial virus (BRSV) vaccine would reduce subsequent treatment for respiratory disease.

Bovine respiratory syncytial virus vaccination was associated with a significant (p<0.05) reduction in treatment rate in one of three groups of calves immunized prior to weaning (−12%) and in calves immunized upon arrival at the feedlot (−4%).

There was no significant (p>0.05) effect of the BRSV vaccine on treatment rate in calves immunized at weaning, in calves immunized upon arrival at the Saskatoon bull test station, or in yearlings immunized upon arrival at the feedlot.

Although the trend in these field trials was to a sparing effect of the BRSV vaccine, the small reduction in treatment rate may not justify the cost of the vaccination program.

     

Detection of squash mosaic virus in seeds of melon (Cucumis melo) by enzyme-linked immunosorbent assay (ELISA)

Squash mosaic virus (SqMV, comovirus) is seed-transmitted in severalCucurbitaceae. Therefore, the use of virus-free seed is important to prevent establishment of this virus in the Netherlands and to avoid spread to other countries.This study was undertaken to develop an enzyme-linked immunosorbent assay (ELISA) for the detection of SqMV in melon seeds. An antiserum was produced to a serotype 1 isolate from melon. Two ELISA variants were investigated viz. an ELISA variant with simultaneous incubation of sample and enzyme conjugate (ELISA 1) and an ELISA variant with successive incubation of sample and enzyme conjugate (ELISA 2). The sensitivity of ELISA was tested by mixing fluor of ground infected and non-infected seeds in different proportions. SqMV was detected by both ELISA variants at dilutions of 1 160 (1 part of infected flour mixed with 159 parts of non-infected flour) or higher after a substrate incubation period of 4 h. However, ELISA 1 gave relatively higher absorbance values than ELISA 2 for nearly all dilutions. Since ELISA 1 is also faster than ELISA 2, ELISA 1 is advised for routine testing. In these test, using subsamples of 100 melon seeds SqMV is detected reliably. ELISA 1 is now used in the Netherlands for routine-indexing of melon seed lots for SqMV.Samenvatting Het pompoenemozaïekvirus gaat over met het zaad van verscheideneCucurbitaceae. Het gebruik van virusvrij zaad is belangrijk om te voorkomen dat het virus zijn intrede doet in Nederland en zich naar andere landen verspreidt.Een antiserum werd geproduceerd tegen een serotype 1 isolaat van meloen. Met behulp van dit antiserum werd een ELISA ontwikkeld om pompoenemozaïekvirus in zaden van meloen aan te tonen. Twee varianten van ELISA werden vergeleken, namelijk een variant waarbij monster en enzymconjugaat gelijktijdig geïncubeerd werden (ELISA 1) en een variant waarbij monster en enzymconjugaat na elkaar geïncubeerd werden (ELISA 2). De gevoeligheid van de ELISA varianten werd uitgetoetst door meel van zieke zaden in verschillende verhoudingen te mengen met meel van gezonde zaden. Het pompoenemozaïekvirus werd met beide ELISA varianten aangetoond in verdunningen van 1 160 (1 deel meel van zieke zaden gemengd met 159 delen meel van gezonde zaden) of hoger na 4 uur incubatie met substraat. ELISA 1 gaf doorgaans hogere extinctiewaarden dan ELISA 2 voor bijna alle verdunningen. Omdat ELISA 1 ook nog sneller is dan ELISA 2, wordt ELISA 1 aanbevolen voor routinematig gebruik. Wanneer voor routinematig gebruik 100 meloenezaden per submonster getoetst worden, kan het pompoenemozaïek virus betrouwbaar worden aangetoond. In Nederland worden momenteel per zaadpartij 20 submonsters van 100 zaden getoetst.     

Reproductive performance of nili-ravi buffaloes after a single injection of GnRH earlypost partum

Summary Sixty dairy buffaloes (second to fourth lactation) from a large buffalo farm were used to compare the effects of single intramuscular injections of 100 µg gondadotrophin releasing hormone (GnRH), 250 µg GnRH or saline given on day 14post partum. The buffaloes had calved at the end of the breeding season (December). Milk samples for progesterone determination were taken at the time of injection and then three times a week either until first insemination or until around day 90post partum. GnRH given at 14 dayspost partum resulted in quicker completion of uterine involution, earlier resumption of ovarian activity, shorter intervals between calving and conception and a better first service conception rate in non-suckled dairy buffaloes. Differences between the results obtained by a GnRH dose level of 100 µg and 250 µg were non-significant. In the post-treatment period cases of prolonged luteal activity were common in all groups of buffaloes. Therefore the sequential administration of GnRH and prostaglandin is suggested for the management of post-partum reproductive activity in problem herds.

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Desempeno Reproductivo De Bufalos Nili-Ravi Despues De Una Sola Inyeccion De GnRH Temprano Despues Del Post-Parto

Resumen Sesenta búfalos lecheros (segunda a cuarta lactancia) pertenecientes a un hato grande fueron utilizados para comparar los efectos de inyecciones intramusculares de 100 µg de GnRH, 250 µg y de solución salina, aplicadas 14 días después del parto. Los búfalos habian parido al final de la estación de pariciones (diciembre). Se tomaron muestras de leche para medir progesterona, en el momento de la inyección y después tres veces por semana hasta la primera inseminación, o hasta cerca de los 90 días post-parto. La GnRH administrada 14 días post-parto, dio como resultado una rápida involución uterina, más rápido retorno a la actividad ovárica, más cortos intervalos entre partos y concepción, y un mejor índice servicio-concepción en búfalos lecheros que no estaban amamantando. Los resultados de dosis de 100 µg y 250 µg no fueron significativos. En el período post-tratamiento, los casos de actividad luteal prolongada fueron comunes en todos los grupos de búfalos. Se sugiere entonces, la administración secuencial de GnRH y prostaglandina, parar el manejo de la actividad reproductiva post-parto en hatos problema.

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Performances De Reproduction Du Buffle Nili-Ravi Apres Une Injection Unique PrecocePost Partum De Gonadotrophine (GnRH)

Résumé Soixante bufflesses laitières (de la seconde à la quatrième lactation), appartenant à une grande ferme d'élevage de buffles, ont été utilisées pour comparer les effets d'une injection unique intramusculaire de 100 µg de gonadotrophine, ou de 250 µg du même produit ou d'une solution de sérum physiologique. Les bufflesses avaient mis bas à la fin de la saison de reproduction soit en décembre. Des prélèvements de lait ont été effectués pour déterminer le taux de progestérone au moment de l'injection d'une part, puis trois fois par semaine d'autre part jusqu'à la première insémination ou aux alentours d'une période de 90 jours après le part. La gonadotrophine, libérée sous forme d'hormone (GnRH), injectée 14 jours après la mise bas a eu pour effet un retour complet plus rapide de l'involution utérine et des intervalles plus courts entre la mise bas et la conception ainsi qu'un meilleur taux de conception à la première monte chez les femelles laitières non allaitantes. Les différences entre les résultats obtenus par une dose de 100/µg ou de 250/µg de gonadotrophine (GnRH) n'étaient pas significatives. Pendant la période post-thérapeutique, des cas d'activité lutéale prolongée ont été courants dans tous les groupes de bufflesses. En conséquence, l'administration séquentielle de GnRH et de prostaglandine est conseillée pour contrôler l'activité post-partum de reproduction dans les troupeaux qui présentent des problèmes de cet ordre.

     

Taste aversion learning in horses

The ability of ponies to learn to avoid a relatively novel food associated with illness was tested in three situations: when illness occurred immediately after consuming a feed; when illness occurred 30 min after consuming a feed; and when illness was contingent upon eating one of three feeds offered simultaneously. Apomorphine was used to produce illness. The feeds associated with illness were corn, alfalfa pellets, sweet feed and a complete pelleted feed. The ponies learned to avoid all the fees except the complete feed when apomorphine injection immediately followed consumption of the feed. However, the ponies did not learn to avoid a feed if apomorphine was delayed 30 min after feed consumption. They could learn to avoid alfalfa pellets, but not corn, when these feeds were presented with the familiar "safe foods," oats and soybean meal. Ponies apparently are able to learn a taste aversion, but there were constraints on this learning ability. Under the conditions of this study, they did not learn to avoid a food that made them sick long after consumption of the food, and they had more difficulty learning to avoid highly palatable feeds.     

Airway hypersensitivity induced by Ascaris suum extract in New Zealand Romney sheep

Sheep from local farms with and without previous exposure to pigs were tested for their skin and airway responses to a commercial Ascaris suum antigen. There was an immediate reaction to intradermal injection of the antigen in 90% of 101 sheep. A bronchial provocation test by aerosol of the same antigen was undertaken on 43 of the sheep with a positive skin reaction. About 70% of sheep showed an immediate airway response to the antigen as an aerosol, reflected as a significant increase in airway resistance and/or decrease of dynamic lung compliance. The mean peak airway resistance and mean lowest dynamic lung compliance were 165% above and 61% below their baselines, respectively. No significant changes were recorded when the same animals were given an aerosol of phosphate buffered saline. Similarly, no correlation was found between the degree of skin reaction and the magnitude of bronchoconstriction (p>0.05). The sheep with previous exposure to pigs showed no significant differences in airway responses to antigen challenge, although they showed significantly greater skin reactions than those without exposure to pigs. These results indicate that the majority of Romney sheep in the Manawatu have a natural skin and airway sensitivity to A. suum antigen and may therefore be used as an animal model to study human airway hypersensitivity. The origin of this sensitivity has yet to be determined.