Pregnancy rates in beef cattle after administering a GnRH agonist 11 to 14 days after insemination.

The objective of our study was to determine the dose-pregnancy rate response of a GnRH agonist injected once during the luteal phase in virgin heifers (four locations) and suckled beef cows (two locations) during the spring of 1989. The same treatments in virgin heifers were used at one location in the fall of 1989. Heifers and cows were inseminated at a synchronized estrus and then assigned randomly to each of three doses (0, 100, or 200 micrograms) of fertirelin acetate administered in 4 ml of saline in a double-blind study after being blocked by inseminator and service sire. Injections were given (i.m.) once on d 11, 12, 13, or 14 after estrus. Pregnancy rates were determined by palpation of the uterus per rectum and(or) by actual calving dates. Overall pregnancy rates for heifers across five locations were 86/201 (43%), 100/197 (51%), and 100/203 (49%) for the 0, 100, and 200 micrograms doses of fertirelin acetate, respectively. Pregnancy rates for heifers at two locations based on calving data were 28/48 (50%), 31/47 (66%), and 34/52 (65%) for the three doses. Both the 100- and 200-micrograms doses increased (P less than .05) pregnancy rates in heifers based on palpation results, whereas only the 200-micrograms dose tended to increase (P = .10) pregnancy rates based on calving results. Pregnancy rates based on palpation for suckled beef cows at two locations were 36/51 (71%), 30/43 (70%), and 34/51 (67%), and the corresponding pregnancy rates based on calving results were 30/41 (73%), 32/36 (89%), and 31/38 (82%) for the 0, 100, and 200 micrograms doses, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of reproductive traits in Bos taurus and Bos indicus crossbred heifers: relationship of age at puberty to length of the postpartum interval to estrus.

Records of age at puberty (AAP) and duration of the postpartum interval to estrus (PPI) for heifers calving first at 2 yr of age were used to determine the relationship between the two reproductive traits. The study from which these records were obtained was designed in a 2 x 2 x 2 factorial arrangement of treatments. Angus x Hereford (AH; n = 148) and Brahman x Hereford (BH; n = 148) heifers were allotted within breed after weaning by weight into light (LW) and heavy (HW) weight blocks. Heifers were assigned by age to different levels of energy (low or high) in diets calculated to reach a target weight of 55% (LE) or 65% (HE) of their projected mature weight by the onset of the breeding period. Data were analyzed within breed and included only records for which both AAP and PPI were available. Pearson correlation coefficients for AAP to PPI were r = -.12 (P = .20) and r = .05 (P = .71) for AH and BH, respectively. Eliminating animals that experienced dystocia from the analyses yielded correlations of r = -.27 (P = .02) and r = .06 (P = .65) for Ah (n = 69) and BH (n = 51), respectively. When energy level, weight block, and energy level x weight block were included in the model for PPI, analyses of variance indicated that PPI among AH heifers was influenced most by the weight at which heifers began the trial after weaning (P = .01) but not by energy level (P = .23) or the interaction of energy level x weight block (P = .48).(ABSTRACT TRUNCATED AT 250 WORDS)     

Extensive lesions of monkeypox in a prairie dog (Cynomys sp)

Monkeypox with extensive lesions was diagnosed in a prairie dog that was involved in a recent human outbreak of monkeypox in the Midwestern United States. Gross lesions included oral ulcers, pulmonary consolidation, enlarged cervical and thoracic lymph nodes, and multifocal, small, white umbilicated plaques in the gastrointestinal wall. Microscopic lesions were extensive in the lungs and consisted of fibrinonecrotic bronchopneumonia with vasculitis and poorly defined eosinophilic intracytoplasmic inclusion bodies in cells thought to be alveolar epithelial cells, histiocytes, and fibroblasts. Multifocal necrotizing lesions, often accompanied by myxedema, were also present in most of the other examined organs. Aggregates of pox viral particles were observed within lesions by transmission electron microscopy. Monkeypox virus infection was confirmed by real-time polymerase chain reaction and virus culture at the Centers for Disease Control and Prevention. This report highlights the difficulties of rapid diagnosis of exotic or emerging diseases and further substantiates the prairie dog as an animal model of monkeypox.     

Pain-related cerebral potentials in response to acute painful electrical stimulation in sheep

Objective To examine associations between late event-related cerebral potential amplitudes and behavioural responses to noxious electrical stimulation as an indicator of acute pain in sheep.
Design Analysis of variance for the effects of stimulus intensity on the behaviour and event-related cerebral potential variables.
Procedure Ninety-six brief constant current electrical pulse trains were presented to the front left leg of eight sheep at four intensities (2.5 to 10 mA) in a randomised order. An event-related cerebral potential and a graded flinch response were recorded for each stimulus and the 24 event-related cerebral potentials at each intensity were averaged to produce a mean waveform. Various components of this waveform were analysed and changes in these measures and the sheep's flinch response, as stimulus intensity increased, were determined.
Results Both the flinch response and some event-related cerebral potential components, that is, peak amplitudes 114 {N1}, 187 {P1}, 318 {P2} and 230 {Pm} ms after stimulus onset, were significantly affected as stimulus intensity increased.
Conclusion These corresponding behavioural and event-related cerebral potential changes indicate the usefulness of using changes in the event-related cerebral potential to measure acute pain in sheep.     

Nutrient balance in the diet of spring calving, pasture-fed dairy cows

AIMS: To report the nutrient composition of pastures fed to spring-calving dairy cows in the Manawatu region of New Zealand, and describe changes in the nutrient composition of these pastures over a 12-month period. Having done this we sought to: (1) compare the nutrient composition of the pasture offered with the nutrient requirements of spring-calving dairy cows; (2) identify periods when individual nutrient surpluses and deficits are likely; and, (3) identify nutrients that demonstrate a high level of variability between sampling occasions. METHODS: Seven farms took part in the study. Each farm was visited monthly from August 1996 to July 1997. Samples of pasture were taken at each visit and submitted for estimation of dry matter (DM), metabolisable energy (ME), crude protein (CP), non-structural carbohydrate (NSC), neutral detergent fibre (NDF), acid detergent fibre (ADF), calcium (Ca), phosphorus (P), magnesium (Mg), sodium (Na), potassium (K), chlorine (Cl), sulphur (S), iron (Fe), copper (Cu) and zinc (Zn), and dietary cation-anion differences (DCAD). RESULTS: Sampled pastures were characterised by low to marginal ME, NSC, Ca, Mg, and Zn concentrations when compared with recommended dietary nutrient concentrations for lactating and non-lactating dairy cattle in New Zealand. Analyses revealed relatively high CP, NDF and K concentrations, and DCAD. CONCLUSIONS: These analyses identify broad trends in the nutrient balance of a pasture-only feeding regime and provide a useful reference for planning feed strategies for spring-calving, pasture-fed dairy herds in this region. Recommended changes to on-farm practice should be made after considering the whole farm system, rather than being made solely on the basis of perceived deficiencies or excesses of individual nutrients.     

Variability of neutrophil and pulmonary alveolar macrophage function in swine

Neutrophils and alveolar macrophages are essential defence mechanisms against bacterial infection of the lung. The purpose of this study was to evaluate the variability of a panel of neutrophil and alveolar macrophage function assays in swine, and to determine if the function of these leukocytes differed at various stages of production. Measured neutrophil functions included chemotaxis, phagocytosis, oxidative burst, and degranulation. Phagocytosis and oxidative burst were measured in alveolar macrophages isolated from bronchoalveolar lavage fluid (BALF). Both neutrophil and alveolar macrophage functions were highly variable from day-to-day and between pigs. Individual pigs did not have consistently high or low neutrophil and macrophage responses over time when compared to their cohorts. Older grower-finisher pigs had significantly greater neutrophil oxidative burst responses than younger suckling and weaner pigs (P < 0.001). Similarly, alveolar macrophages from suckling and early weaner pigs less than 40 days of age had significantly lower oxidative burst responses than those from older pigs (P = 0.02). Age-related variation in phagocytosis, chemotaxis, or granule secretion were not detected. These results establish baseline data for individual and age-related variation in swine leukocyte function, and form a basis for further evaluation of the contribution of non-infectious factors to development of the porcine respiratory disease complex.     

Synchronizing estrus and(or) ovulation in beef cows after combinations of GnRH, norgestomet, and prostaglandin F2alpha with or without timed insemination

Three experiments were conducted to induce estrus and(or) ovulation in 1,590 suckled beef cows at the beginning of a spring breeding season. In Exp. 1, 890 cows at three locations were allotted to three treatments: 1) GnRH on d -7 + prostaglandin F2alpha (PGF2alpha) on d 0 (Select Synch); 2) GnRH on d -7 + PGF2alpha on d 0 (first day of the breeding season) plus a norgestomet implant (NORG) between d -7 and 0 (Select Synch + NORG); or 3) two injections of PGF2alpha given 14 d apart (2xPGF2alpha). More (P < 0.05) cycling cows were detected to have been in estrus after both treatments that included GnRH, whereas, among noncycling cows, the addition of norgestomet further increased (P < 0.05) the proportion in estrus. Pregnancy rates were greater (P < 0.01) among noncycling cows after treatments that included GnRH. For cows that calved >60 d before the onset of the breeding season, conception rates were greater (P < 0.01) than those that calved < or =60 d regardless of treatment, whereas days postpartum had no effect on rates of detected estrus. When body condition scores were < or =4 compared with >4, rates of detected estrus (P < 0.05) and conception (P = 0.07) were increased. In Exp. 2, 164 cows were treated with the Select Synch + NORG treatment and were inseminated either after estrus or at 16 h after a second GnRH injection (given 48 h after PGF2alpha). Conception and pregnancy rates tended (P = 0.08) to be or were less (P < 0.05), respectively, for noncycling cows inseminated by appointment, but pregnancy rates exceeded 53% in both protocols. In Exp. 3, 536 cows at three locations were treated with the Select Synch protocol as in Exp. 1 and inseminated either: 1) after detected estrus (Select Synch); 2) at 54 h after PGF2alpha when a second GnRH injection also was administered (Cosynch); or 3) after detected estrus until 54 h, or in the absence of estrus, at 54 h plus a second GnRH injection (Select Synch + Cosynch). Conception rates were reduced (P < 0.01) in cows that were inseminated by appointment. An interaction of AI protocol and cycling status occurred (P = 0.05) for pregnancy rates with differing results for cycling and noncycling cows. Across experiments, variable proportions of cows at various locations (21 to 78%) were cycling before the breeding season. With the GnRH or GnRH + NORG treatments, ovulation was induced in some noncycling cows. Conception rates were normal and pregnancy rates were greater than those after a PGF2alpha program, particularly when inseminations occurred after detected estrus.     

Control ofFasciola gigantica with triclabendazole in Indonesian cattle

Summary The efficacy of triclabendazole (TCBZ) against natural infections with Fasciola gigantica was evaluated in a field study using 102 Indonesian cattle. The animals were divided into two groups; one received TCBZ at 12 mg/kg orally every eight weeks for one year while the other remained untreated. Relative to controls theFasciola faecal egg count in treated animals was significantly reduced (P<0·01) to almost zero at all observations. There were no differences between the groups in blood values and body mass gain. Plasma glutamate dehydrogenase (GLDH) levels in treated animals were reduced to within normal values, whereas those in controls remained above normal throughout. Although plasma gamma glutamyl transferase (GGT) levels remained within the normal range in both groups they were consistently higher in control than in treated animals. However, both GLDH and GGT levels in control animals were considerably lower than those reported by others in experimental low-level chronic fasciolosis, which suggests that only mild liver damage was caused by small numbers ofF. gigantica in these animals. In addition to considerations of disease prevalence and economic data from abattoirs, control strategies for fasciolosis in Indonesian cattle require an evaluation of losses due to subclinical disease.

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Resumen Se evaluó en el campo, la eficacia de triclabendazole (TCBZ) contra infecciones naturales conFasciola gigantica, utilizando 102 bovinos indonesios. Los animales se dividieron en dos grupos; uno recibió TCBZ en dosis de 12 mg/kg oralmente cada ocho semanas por un a≈no, mientras que el otro permaneció sin tratamiento. En comparación a los controles, los conteos de huevos de fasciola en los animales tratados se redujeron significativamente (P<0·01), hasta casi cero en todas las observaciones. No hubo diferencias entre los grupos en cuanto a valores sanguineos y ganacia de peso. Los niveles plasmáticos de deshidrogenasa glutámica se redujeron a valores normales en los tratados, mientras que en los controles permanecieron por encima de los valores normales. Aunque los valores plasmáticos de gama glutamil transferasa permanecieron dentro de los valores normales en ambos grupos, éstos fueron consistentemente mayores en los controles que en los tratados. Sin embargo, ambos niveles enzimáticos en los animales controles, fueron considerablemente más bajos que aquellos informados por otros investigadores, en fascioliasis crónica de nivel bajo, lo que sugiere que solamente se produjo un da?o hepático menor en estos animales experimentales. La fascioliasis en Indonesia requiere una evaluación de las pérdidas debido a la enfermedad subclínica.

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Résume L'efficacité du triclabendazole (TCBZ) contre les infestations naturelles àFasciola gigantica a fait l'objet d'une évaluation sur le terrain portant sur 102 bovins ceux-ci ont été divisés en 2 groupes, l'un recevant le TCBZ à la dose de 12 mg/kg par voie orale toutes les 8 semaines pendant un an, l'autre restant non traité, à titre de témoin. En ce qui concerne les contr?les, le nombre d'oeufs deFasciola chez les animaux traitès a baissé de fa?on significative (avecP<0,01, atteignant presque 0 pour toutes les observations). On n'a noté aucune différence entre les deux lots quant aux valeurs hématologiques et au gain corporel global. Les niveaux plasmatiques de la déhydrogénase du glutamate (GLDH) sont descendus chez les animaux traités au dessous des valeurs normales, alors que chez les animaux témoins ils se sont constamment maintenus au dessus. Quoique les taux plasmatiques de la gamma glutamyl-transférase (GGT) soient restés á l'intérieur des variations normales dans les 2 groupes, ils ont été régulièrement plus élevés dans le lot témoin que dans le groupe traité. Cependant les 2 niveaux (GLDH et GGT) chez les animaux témoins ont été considérablement moins élevés que ceux indiqués par d'autres auteurs dans la fasciolose chronique experimentale de faible intensité, ce qui montre queF. gigantica en petit nombre a causé seulement une légére atteinte hépatique chez ces animaux. En complément des considérations relatives à la prévalence de la maladie et aux données économiques recueillies dans les abattoirs, les stratégies de lutte contre la fasciolose bovine en Indonésie passent par une évaluation des pertes consécutives aux aspects subcliniques de la maladie.