Effect of anthelmintic treatment on sexual maturation in prepubertal beef heifers

Heifers treated with ivermectin at weaning have been reported to reach puberty at a younger age and lighter weight than untreated heifers. We tested the hypothesis that heifers administered ivermectin would respond with earlier follicular development and a greater LH response to a 1-mg estradiol-17beta challenge (E2C) than untreated heifers. Fall-born Angus heifers (n = 32) were randomly assigned on 284 +/- 9 d of age (215.5 +/- 20.8 kg) to receive ivermectin (IVR) or albendazole (ALB), IVR + ALB, or to remain as untreated controls (CONT). Each group (n = 8) was housed separately in adjacent pens throughout the trial and managed to gain .8 kg/heifer on a ration containing 13.2% CP, 58.8% TDN, and 49.9% DM. The CONT heifers received an additional 2.27 kg/heifer of corn silage and 1.59 kg/heifer of corn daily to maintain ADG at comparable levels. Individual body weight was recorded weekly, and nematode eggs per gram (EPG) of feces were measured every 21 d. Ultrasonography was performed on alternate days starting 2 wk prior to E2C to characterize follicular wave patterns. Follicles were separated into classes (C1 [3 to 5 mm], C2 [6 to 9 mm], and C3 [10 mm]) and sizes (largest [LF], second [SLF], third [TLF], and fourth largest follicles [FLF]). The sizes of the regressing dominant follicle 1 (DF1) and the progressing dominant follicle 2 (DF2) were also determined. Serum concentrations of LH were determined from hourly jugular blood samples collected 8 to 24 h after injection of E2C. The IVR + ALB treatment group had more C3 follicles than ALB and CONT (P < .07). The IVR-treated heifers had larger TLF than ALB and CONT (P < .04). The IVR- and IVR + ALB-treated heifers had larger FLF and DF2 than ALB and CONT (P < .1). Least squares means for DF2 were 9.5 +/- .5, 8.0 +/- .4, 9.5 +/- .3 and 8.3 +/- .3 mm, for IVR, ALB, IVR + ALB and CONT, respectively (P = .02 for treatment effect). The E2C-induced serum LH concentration did not differ with respect to treatment. We conclude that heifers administered IVR display increased follicular development, supporting our earlier investigations regarding reduced age at puberty in heifers treated with IVR near weaning.     

Relationship between group B streptococcal serotypes and cell surface hydrophobicity.

Cell surface hydrophobicities of streptococci of serological group B were determined by the adherence of the bacteria to hexadecane droplets. A significant adherence to hexadecane was observed with the group B streptococcal type reference strains Ib, V, Ic, R and X, but not with those of serotype Ia, II, III and IV. Cultivation of the bacteria in microcapsule-inducing media reduced the hexadecane adherence properties. The adherence to hexadecane was not related to fibrinogen binding properties of the cultures. Screening a large number of group B streptococci isolated from humans and bovines revealed that those with polysaccharide type antigen alone were generally hydrophilic, those with protein antigen alone or with protein antigen in combination with polysaccharide antigen were mostly hydrophobic. Cultivation of the bacteria under microaerobic conditions or after a single mouse passage enhanced microcapsule production and correspondingly reduced the hexadecane adherence values. Treatment of the bacteria by guanidinium chloride or by neuraminidase enhanced the hexadecane adherence. The hydrophobic component on group B streptococcal surface appeared to be partly inactivated by heat or proteolytic treatment of the bacteria.     

Clinical pulmonary function testing in dogs and cats.

Pulmonary function testing is a relatively new area in clinical veterinary medicine, with few individuals currently obtaining TBFVL and pulmonary mechanics on a clinical cases of respiratory disease in dogs and cats. ABG analysis is a technique available to all veterinarians through commercial laboratories or local hospitals. Information obtained from these tests will allow for a better understanding of the pathophysiology of naturally occurring diseases as well as assisting in the determination of the efficacy of various therapeutic agents (such as bronchodilators), which to date has been lacking in veterinary medicine.     

Genotype and treatment biases in estimation of carcass lean of swine.

Carcasses of 181 barrows, representing five genotypes, 1) H x HD, 2) SYN, 3) HD x L[YD], 4) L x YD, and 5) Y x L (H = Hampshire, D = Duroc, SYN = synthetic terminal sire line, L = Landrace, and Y = Yorkshire), and two levels of ractopamine (RAC) treatment (0 and 20 ppm) were completely dissected and the data were used to examine genotype and treatment (RAC) biases in estimation of fat-standardized lean weight and to evaluate accuracies and precisions realized by use of equations based on variables derived from different technologies. Independent variables used to establish regression equations represented technologies of direct carcass measurements, optical probe data, TOBEC (total body electrical conductivity) readings, and dissected (DHMLN) and fat-standardized (FSHMLN) ham lean. Genotype bias existed when any equation from a single technology was used and was minimized by combining FSHMLN with one TOBEC reading, carcass length, and the probe measurement of 10th rib fat depth. Large RAC biases appeared when equations from direct carcass measurements or optical probe data were used and were minimized by an equation using either DHMLN or FSHMLN. A practical equation with relatively high R2 value and small genotype and RAC biases were developed by combining TOBEC readings with direct carcass measurements of 10th rib fat depth and warm carcass weight.     

Serum resistance and virulence of Escherichia coli isolated from turkeys

Twenty-five strains of Escherichia coli isolated from turkeys were characterized for their serum resistance and virulence. An in vitro bactericidal assay was used to determine the serum resistance of E coli. Virulence was determined by survival time after IV inoculation of each strain into 3-week-old turkeys. Serum-resistant E coli strains were generally found to be virulent for turkeys, whereas serum-sensitive E coli strains were avirulent. Of the 25 strains, 18 strains were placed in the 2 categories of serum-resistant/virulent and serum-sensitive/avirulent. Five strains were serum-resistant and avirulent, and 2 strains were serum-sensitive and virulent. Serum resistance appears to be an important determinant of virulence for E coli in turkeys; however, the requirement for other virulence factors, in addition to serum resistance, was suggested by the finding that 5 serum-resistant strains were avirulent in turkeys.     

Immune and bone properties of chicks consuming corn contaminated with a Fusarium that induces dyschondroplasia

A study was conducted to contrast the dyschondroplasia-inducing capability of several species of Fusarium with that of the natural fungi found in poultry diets and litter. Day-old broiler chicks were fed pure corn cultures of specific fungal isolates for 3 weeks. Humoral immunity to sheep red blood cells (SRBC), body weight, valgus and varus leg deformities, incidence of dyschondroplasia, and mechanical properties of the tibiotarsi were examined. F. equiseti #15 was the only fungal isolate to induce dyschondroplasia to any significant degree, which confirmed previous work in Minnesota. This isolate also suppressed growth rate and humoral immunity, although dyschondroplasia sometimes did occur without associated immunosuppression and growth depression. Bone strength of the tibiotarsal diaphysis was normal, and gross lesions of valgus and varus leg deformities did not appear to be related to the incidence of dyschondroplasia in the 3-week-old chicks.     

Seizures as a manifestation of primary hyperparathyroidism in a dog

Hypercalcemia caused by primary hyperparathyroidism was believed to be responsible for seizures in a dog. A diagnostic evaluation showed no primary causes of seizures. After surgical excision of the adenomatous parathyroid gland, phenobarbital treatment was discontinued, without recurrence of seizures.     

The coefficient of dominance is not (always) estimable with biallelic markers

The genetic relationship among individuals at one locus is characterized by nine coefficients of identity. The coefficients of inbreeding, coancestry and dominance (or fraternity) are just linear functions of them. Here, it is shown how they can be estimated using biallelic and triallelic markers using the method of moments, and comparisons are made with other methods based on molecular coancestry or molecular covariance. It is concluded that in the general case of dominance and inbreeding with biallelic markers, only the coefficients of inbreeding and coancestry can be estimated, but neither the single coefficients of identity nor the coefficient of dominance can be estimated. More than two alleles are required for a full estimation as illustrated with the triallelic situation.     

The Role of Recreational Motivation in the Birding Participation–Environmental Concern Relationship

Previous research has generally not found a strong relationship between participation in outdoor recreation and environmental concern. Research has suggested, however, that the motivation underlying recreation can mediate this relationship for some nature-based recreation groups. We hypothesized that the motivation underlying participation in birding mediates the participation–environmental concern relationship. We collected data via mail-back surveys from 529 American Birding Association members. Using structural modeling, we compared a direct effects model with partial and full mediation models with motivation variables as the mediators. The partial mediation model was weakly supported for two out of three motivation variables. Fit indices showed all models to have less than adequate fit. The results suggested that participation may not lead to environmental concern and that other variables, including motivation, may be more influential.