Temporal Relationships and Repeatability of Follicle Diameters and Hormone Concentrations within Individuals in Mares

Data were collected daily from 23 mares during two consecutive interovulatory intervals (IOIs). Several significant (p < 0.05) new observations on temporal relationships were made. The FSH increase that begins before ovulation temporarily plateaued on the day of discharge of follicular fluid into the peritoneal cavity in association with ovulation. During the declining portion of the pre-ovulatory oestradiol surge, an abrupt reduction in the rate of decrease occurred in synchrony with the peak of the LH surge and is consistent with a negative effect of LH on oestradiol. Repeatability within mares was based on the following positive and significant correlations between the two IOIs: (i) length of the interval between ovulations and between ovulation and the beginning of follicle deviation; (ii) diameter of the pre-ovulatory follicle on days -3 to -1; (iii) number of follicles in diameter classes of 2–5 mm (correlation for 22/23 days of the IOI), 5.1–10 mm (18/23 days), 10.1–15 mm (12/23 days) and 15.1–20 mm (12/23 days) and (iv) concentrations of FSH (18/23 days) and LH (22/23 days). The greatest repeatability for the follicle-diameter classes occurred in the 2–5 mm class, and thereafter the repeatability progressively decreased as the diameters for the classes increased. Results demonstrated measurable repeatability within mares for several end points between consecutive IOIs.     

Growth response to increasing doses of microencapsulated vitamin B12 and related changes in tissue vitamin B12 concentrations in cobalt-de cient lambs

AIM: To investigate growth responses of cobalt-deficient lambs to increasing doses of microencapsulated vitamin B₁₂, and to measure associated changes in serum and liver vitamin B₁₂ concentrations over 243 days.

METHODS: From a flock grazing pastures that had low cobalt (Co) levels (about 0.06 mg Co/kg dry matter), 4-6-week-old lambs (n=137) were assigned to four groups and received either no treatment or a subcutaneous injection of 3.0, 4.5 or 6.0 mg of microencapsulated vitamin B₁₂ on Day 1. At approximately monthly intervals, all lambs were weighed and blood samples were collected from a selection (n=10) of monitor animals, up to Day 243. Liver biopsies were also carried out on the monitor lambs (n=8) on Days 1, 124 and 215.

RESULTS: The vitamin B₁₂-treated lambs grew significantly faster (p<0.001) than untreated animals. Liveweights after 243 days were 28, 45, 45 and 47 kg for the untreated, 3.0, 4.5 and 6.0 mg vitamin B₁₂-treated lambs, respectively. Of the initial group of untreated lambs, 68% had to be removed before the end of the trial because of substantial weight loss, but none of the treated animals were similarly afflicted. Serum vitamin B₁₂ concentrations increased in all vitamin B₁₂-treated lambs, reaching a peak at Day 25, and those of the 4.5 and 6.0 mg vitamin B₁₂-treated lambs remained significantly higher (except at Day 124) than the untreated lambs to Day 187. However, at Day 124, but not Day 215, the liver vitamin B₁₂ concentrations of treated lambs were two to three times higher than those of controls.

CONCLUSIONS: The growth rates of Co-deficient lambs were markedly improved by injection of 3.0, 4.5 or 6.0 mg of microencapsulated vitamin B₁₂, and liveweights were maintained for at least 243 days. Serum vitamin B₁₂ concentrations were related to this growth response; concentrations of <220 pmol vitamin B₁₂/l were associated with a 95% probability that lambs were Co-deficient and would thus respond to Co/vitamin B₁₂ supplementation. Based on these data, the current New Zealand reference criteria for Co deficiency should be reviewed.

CLINICAL SIGNIFICANCE: An injection of 3 mg microencapsulated vitamin B₁₂2 given to lambs at tailing will treat Co deficiency and will increase and maintain liveweights in a flock for up to 8 months.     

Genetic Structure of Mycosphaerella populorum (Anamorph Septoria musiva) Populations in North-Central and Northeastern North America

ABSTRACT In order to characterize the genetic variation of the poplar pathogen Mycosphaerella populorum (anamorph Septoria musiva), we have studied seven North American populations using the polymerase chain reaction random amplified polymorphic DNA (RAPD) technique. The fungal populations were sampled in 2001 and 2002 by obtaining 352 isolates from cankers and leaf spots in hybrid poplar plantations and adjacent eastern cottonwood (Populus deltoides). A total of 21 polymorphic RAPD markers were obtained with the six RAPD primers used. A fine-level scale analysis of the genetic structure within the populations revealed that subpopulations sampled on P. deltoides and on hybrid trees were not significantly differentiated. In contrast, analyses performed on the entire data set showed high levels of haplotypic diversity and moderate to high genetic differentiation, with 20% of the expected genetic diversity found at the interpopulation level. Moreover, a high and significant correlation between genetic and geographic distances among populations was found, suggesting isolation by distance of the sampled populations. Although the occurrence of the sexual stage of this fungus remained unclear in field populations, five of the six populations were at gametic equilibrium for RAPD loci, suggesting the occurrence of recombination episodes in Septoria musiva populations. Overall, S. musiva appears to consist of differentiated subpopulations, with both asexual and sexual recombination contributing to the local level of genetic structure.     

Quantification of Armillaria rhizomorphs in Wisconsin aspen sucker stands

Weights of rhizomorphs of undetermined Armillaria sp. obtained using ring-trench and core soil sampling methods around aspen stumps in stands at different intervals after harvest were correlated. The core method was used to sample a second series of stands twice (at an interval of two growing seasons) at radial distances of 0.5, 1.0, and 1.5 meters from stump centers. Stands were uncut (at both samplings) or 3, 6, 9, 12, or 15 years after harvest (at the time of the initial sampling). Rhizomorphs were obtained from less than half the cores from the uncut stand, and the quantities (weights and lengths) were relatively small from both samplings. Mean numbers of soil cores yielding rhizomorphs and the mean quantities obtained generally increased as a function of the interval after harvest (and from the first to the second sampling), except for the oldest stand.     

Myotonia associated with hyper-adrenocorticism in two dogs

Two dogs developed a disabling gait abnormality characterised by stiffness. The abnormality was consistent with a diagnosis of myotonia secondary to hyper-adrenocorticism. The first dog had iatrogenic hyperadrenocorticism, and its signs improved substantially after corticosteroid administration was gradually withdrawn. The second had pituitary-dependent hyperadrenocorticism, but myotonic signs progressed despite effective mitotane therapy. Procainamide administration reduced the myotonic stiffness in the second case.     

Sphaeropsis sapinea and Water Stress in a Red Pine Plantation in Central Wisconsin

ABSTRACT A study was conducted to determine the effects of water stress resulting from competing vegetation on disease development of Sphaeropsis sapinea in red pine plantations. A 9-year-old plantation was selected in 1992 and experiments were conducted for three consecutive years. Four treatments were assigned at random to individual trees: no treatment, herbicide to kill surrounding weeds, supplemental water, and both herbicide and supplemental water. Two isolates of each S. sapinea morphotype (A and B) were used to inoculate wounded lateral shoots. Disease development was measured as the maximum distance below the inoculation site at which necrotic needles were observed. Nonwatered trees with competing vegetation (nontreated condition) had significantly lower predawn needle water potentials (more water stress) and more severe disease development than trees that received the herbicide, water, or combined herbicide and water treatments. The most severe disease occurred in the driest year and the least in the wettest year. Competing vegetation indirectly affected disease development by inducing water stress, even in relatively moist years, on trees previously considered well established. Isolates of morphotype A were more aggressive than isolates of morphotype B. Conclusions from this research have implications for sustainable management of the region's conifer forests.     

Differential Inhibition of Sphaeropsis sapinea Morphotypes by a Phenolic Compound and Several Monoterpenes of Red Pine

ABSTRACT The in vitro effects of a red pine phenolic compound (pinosylvin), a phenolic compound common to other species (tannic acid), and the major red pine monoterpenes (alpha-pinene, beta-pinene, and delta-3-carene) on spore germination and mycelial growth of Sphaeropsis sapinea were examined. Two A and two B morphotype isolates were used. At 88 mug/mm(2), pinosylvin inhibited spore germination of all four isolates (98 to 100%). At 8.8mug/mm(2), spore germination of B isolates was inhibited more than that of A isolates (73 versus 30%). Pinosylvin also inhibited mycelial growth of B isolates more than that of A isolates (84 versus 13% at 88 mug/mm(2)). Tannic acid stimulated or had little affect on spore germination and had little affect on mycelial growth of either morphotype. Spore germination of B isolates was inhibited more than that of A isolates by beta-pinene at saturation (79 versus 37%). Spore germination of B isolates was inhibited and germination of A isolates was stimulated by delta-3-carene below saturation (49 versus -7%). Mycelial growth of B isolates was inhibited more than that of A isolates by all monoterpenes at saturation. Differences observed between morphotypes below saturation were significant only for beta-pinene. These results demonstrate the biological activity of a phenolic compound and monoterpenes that occur in red pine. The differential responses might provide means of distinguishing morphotypes and offer a potential explanation for ecological specialization.