Growth patterns of two lines of Angus cattle selected using predicted growth parameters.

Linear functions of body weight and condition score at weaning and 18 mo of age were used to predict the mature weight (A) and maturing rate (k) parameters of an asymptotic growth model of Angus cows at the Subtropical Agricultural Research Station, Brooksville, FL. From 1981 through 1988 a heavy-mature-weight line (Line A) and a rapid-maturing line (Line K) were selected based on predicted A and k values. Linear contrasts (A-K) of least squares means for weight at fixed ages indicated that the weight difference between lines increased from birth to maturity during the period of the study. Animals from Line A were heavier (P less than .01) at all ages. A negative response in maternal ability, relative to increased growth potential of their calves, seems to have occurred in the cows of Line A. Mature weight was reached at approximately 4.5 yr of age in Line K and at approximately 5.5 yr in Line A. Brody's three-parameter and Richards' four-parameter functions were fitted to 2,855 quarterly weights of cows, from birth to 6.5 yr of age, to estimate the average growth curve for each line. Brody's model gave better estimates of weights from 18 mo to maturity, but the asymptotic residual mean squares were slightly higher because early weights were overestimated. Linear and nonlinear regression analyses of weight-age data and comparisons of degree of maturity at different premature ages showed differences in the growth patterns of the two lines selected for early predicted values of A and k.     

Detection of Ehrlichia risticii using an avidin-biotin-immunoperoxidase staining system

An indirect immunoperoxidase procedure using a specific anti-Ehrlichia risticii monoclonal antibody and an avidin-biotin-peroxidase staining method was used to detect E. risticii antigen in infected P388D1 murine monocytes. Several different methods of cytological fixation were used, including acetone (15 min), 95% ethanol (15 min), Bouin's fixative (5 hr), and 10% buffered neutral formalin (24 hr). The E. risticii organisms were labeled effectively and identified in cells fixed with acetone and ethanol. However, infected P388D1 cells fixed in 10% formalin or Bouin's fixative required enzymatic digestion with 1.0% trypsin for 15 min at 37 C before positive results were evident. This indirect immunoperoxidase avidin-biotin staining procedure proved to be a sensitive assay for the detection of intracellular E. risticii and may be an effective diagnostic procedure for formalin-fixed paraffin-embedded tissue.     

Duration of pituitary and adrenocortical suppression after long-term administration of anti-inflammatory doses of prednisone in dogs.

Duration and magnitude of hypothalamic-pituitary-adrenal axis suppression caused by daily oral administration of a glucocorticoid was investigated, using an anti-inflammatory dose of prednisone. Twelve healthy adult male dogs were given prednisone orally for 35 days (0.55 mg/kg of body weight, q 12 h), and a control group of 6 dogs was given gelatin capsule vehicle. Plasma cortisol (baseline and 2-hour post-ACTH administration) and plasma ACTH and cortisol (baseline and 30-minutes post corticotropin-releasing hormone [CRH] administration) concentrations were monitored biweekly during and after the 35-day treatment period. Baseline plasma ACTH and cortisol and post-ACTH plasma cortisol concentrations were significantly (P less than 0.05) reduced in treated vs control dogs after 14 days of oral prednisone administration. By day 28, baseline ACTH and cortisol concentrations remained significantly (P less than 0.05) reduced and reserve function was markedly (P less than 0.0001) reduced as evidenced by mean post-CRH ACTH, post-CRH cortisol, and post-ACTH cortisol concentrations in treated vs control dogs. Two weeks after termination of daily prednisone administration, significant difference between group means was not evident in baseline ACTH or cortisol values, post-CRH ACTH or cortisol values, or post-ACTH cortisol values, compared with values in controls. Results indicate complete hypothalamic-pituitary-adrenal axis recovery 2 weeks after oral administration of an anti-inflammatory regimen of prednisone given daily for 5 weeks.     

Morphologic changes in the mammary gland of megestrol acetate-treated and untreated cats: a retrospective study

Abnormal mammary gland growth is a side effect of progestin therapy in some cats. In this retrospective study, the nature and significance of morphologic changes in the mammary gland of 17 megestrol acetate (MA)-treated cats were compared to mammary lesions in 97 untreated cats. Fourteen out of 17 MA-treated cats had non-neoplastic mammary lesions including fibroepithelial hyperplasia (nine cats), lobular hyperplasia (three cats), and duct ectasia (two cats); whereas three MA-treated cats had mammary neoplasms including one adenoma and two carcinomas. Although MA has been causally linked to mammary cancer in cats, only mammary fibroepithelial hyperplasia was clearly associated with MA therapy in this study. Fibroepithelial hyperplasia occurred in older (average age 8.1 years) neutered male and female cats in the MA-treated group and in younger (average age 2.1 years) female cats in the untreated group. Morphologically, both intraductal and solid fibroepithelial growth patterns were seen. Intraductal fibroepithelial hyperplasia was further subdivided into papillary and circumferential types. An apparent greater association between MA therapy and the intraductal types of fibroepithelial hyperplasia was noted. Furthermore, it appears likely that mammary lobular hyperplasia also is linked to MA therapy. Possible mammatrophic effects of MA and other growth-promoting agents in the cat are discussed.     

Insulin-like growth factor I receptor analysis of satellite cell-derived myotube membranes established from two lines of Targhee rams selected for growth rate

Ovine-derived fibroblasts were used to validate an insulin-like growth factor I (IGF-I) membrane-receptor binding assay system. Competitive binding using fibroblasts revealed that half-maximal inhibition of 125I-IGF-I binding by IGF-I was 2.3 nM. SDS-polyacrylamide gel electrophoresis analysis of specific protein-associated 125I-IGF-I was consistent with the migration of 125I-IGF-I-labeled Type I IGF receptor alpha-subunits at Mr 133,000 daltons. Further, the efficiency of two cell solubilization methods was examined and time-dependent binding equilibrium was determined for the membrane assay system. Satellite cell-derived myotubes were subsequently isolated from primary satellite cell cultures established from the semimembranosus muscles of high and low efficiency-of-gain (EOG) Targhee rams, and IGF-I receptor dynamics were measured. A membrane competitive binding study revealed that half-maximal inhibition of 125I-IGF-I binding was achieved by 1-ng IGF-I for low, and 10-ng IGF-I for high, EOG myotube membrane preparations. Kd values were similar between the high EOG (4.78 nM) and low EOG (2.95 nM) groups; however, receptor concentrations (Bmax) appeared to differ between groups. High EOG membrane receptor Bmax was 3.88 pmole/micrograms protein (19.87 pmole/micrograms DNA), whereas low EOG membrane receptor Bmax was 1.22 pmole/micrograms protein (9.28 pmole/micrograms DNA). These preliminary findings support the hypothesis that genetic selection for EOG results in altered satellite cell responsiveness to IGF-I.     

Dense Cultivation and Fertilization for Higher Yield of Thyme (Thymus vulgaris L.)

Thyme ( Thymus vulgaris L.) plants were spaced at 15, 30 or 45 cm distances in a clay-loamy soil. They received different levels of nitrogen and phosphorus, besides a constant level of potassium. The results showed, that the wider spacing promoted the growth and production of herb and oil per plant, however dense cultivation significantly increased the yields of herb and oil per unit area. In all cases, the applied fertilization treatments significantly increased the productivity per unit area. Dense cultivation accompanied with higher levels of fertilization proved to be very usefull. The essential oil content was not influenced by either the plant spacing or fertilization treatments applied in this study.