Use of recombinant gonadotropin-releasing hormone antigens for immunosterilization of beef heifers.
The objectives of this study were to evaluate the effects of immunization against recombinant GnRH fusion proteins and growth promotants on onset of puberty, feedlot performance, and carcass characteristics of beef heifers. Heifers were immunized against an ovalbumin fusion protein containing 7 GnRH peptides (oGnRH, n = 12), a thioredoxin fusion protein containing 7 GnRH peptides (tGnRH, n = 12), a combination of oGnRH plus tGnRH (otGnRH, n = 12), or a combination of ovalbumin and thioredoxin (control, n = 11). Each heifer received a primary immunization containing 1 mg of protein in 1 mL of adjuvant injected into the mammary gland at wk 0 (mean age = 38 wk) and booster immunizations at wk 6 and 12. Six heifers within each treatment received Synovex H implants at wk -2. Weekly blood samples were collected from wk -2 to 26 for determination of serum progesterone concentrations and GnRH antibody titers. In GnRH-immunized heifers, GnRH antibody titers increased after the first booster injection, peaked after the second booster injection, and remained elevated through the end of the study (P < 0.01). Heifers immunized against oGnRH achieved greater (P < 0.05) GnRH antibody titers than tGnRH heifers but did not differ (P = 0.20) from otGnRH heifers. During the 26-wk study, ovulation was prevented (P < 0.05) in 10 out of 12, 12 out of 12, 11 out of 12, and 0 out of 11 tGnRH, oGnRH, otGnRH, and control heifers, respectively. At slaughter, uterine weights were lighter (P < 0.01) for GnRH-immunized heifers than control heifers. Synovex H-implanted heifers had greater (P < 0.05) ADG from wk -2 to 26, greater LM area, and lesser percentages of KPH, yield grade, and quality grade than nonimplanted heifers, regardless of the immunization treatment. Immunization against GnRH fusion proteins resulted in production of antibodies against GnRH that prevented ovulation in 92% of the heifers without affecting feedlot or carcass performance. Implanting heifers with Synovex H improved ADG, LM area, and yield grade. Improvements in delivery of the oGnRH vaccine may provide a feasible alternative to surgical spaying of heifers.
Effects of immunization against luteinizing hormone-releasing hormone and treatment with trenbolone acetate on reproductive function of beef bulls and steers.
The objectives of this study were 1) to evaluate the ability of trenbolone acetate (TBA) administered in tandem with LHRH immunization to suppress reproductive function in bulls and 2) to examine the effects of LHRH and androgen (TBA) signaling on pituitary gland function. Forty-four Angus × Hereford crossbred calves (BW=225 ± 2 kg; age=187 ± 6 d) received castration, LHRH immunization, or TBA administration in a 2 × 2 × 2 factorial design. Treatment groups receiving LHRH immunization contained 6 animals, whereas other treatment groups contained 5 animals. Animals immunized against LHRH received a primary injection and 2 booster injections of ovalbumin-LHRH-7 fusion protein on d 0, 42, and 196, respectively. Animals treated with TBA were implanted on d 224. Serum LHRH antibodies increased (P<0.05) after each booster for immunized animals, but were negligible in nonimmunized animals throughout the experiment. Serum testosterone concentration (P<0.001) and scrotal circumference (P<0.05) were depressed in LHRH-immunized bulls compared with nonimmunized bulls by d 84 and 168 of the experiment, respectively. Treatment with TBA tended (P=0.08) to decrease serum testosterone concentrations of nonimmunized bulls. Weights of testes at slaughter were decreased (P<0.001) for LHRH-immunized (232 ± 41 g) compared with nonimmunized (752 ± 45 g) bulls, but did not differ (P=0.80) between TBA-implanted (500 ± 49 g) and nonimplanted bulls (484 ± 36 g). Both LHRH immunization and castration decreased pituitary gland stores of LH and FSH (P<0. 001). There was no effect (P>0.10) of TBA on pituitary gland FSH content and only a tendency (P=0.09) to increase pituitary gland LH content. Immunization against LHRH decreased expression of LH β-subunit and common α-subunit genes (P<0.001). Castration increased expression of LH β-subunit and common α-subunit genes (P=0.02). Treatment with TBA further suppressed (P=0.04) α-subunit mRNA expression in LHRH-immunized steers. In summary, LHRH immunization decreased synthesis and storage of LH and decreased storage, but not synthesis of FSH in bulls. The increased synthesis of LH and FSH in nonimmunized, but not LHRH-immunized steers suggests that castration removes the negative feedback on gonadotropin synthesis but that LHRH is still needed for release of these hormones. Androgen replacement with TBA did not restore the negative feedback control of gonadotropin synthesis.
Instrumentation and Automated Photometric Titration Procedure for Total Acidity Determination in Red Wine Employing a Multicommuted Flow System
An automated procedure for photometric titration of red wine and associated instrumentation is described. The procedure was based on the flow-batch approach implemented employing multicommutation. The photometric detection was carried out using a homemade LED-based photometer. The mixing device, LED, and photodetector were attached to the titration chamber in order to form a compact and small-sized unit. The flow system comprised an automatic injector and three-way solenoid valves, which were controlled by a microcomputer through an electronic interface card. The software, written in Quick BASIC 4.5, was designed with abilities to accomplish all steps of the titration procedure including data acquisition and real-time processing to decide about the course of titration in the following step and so forth, until the titration endpoint was reached. The usefulness of the proposed titration system was demonstrated by analyzing red wine samples. When results were compared with those obtained using the AOAC reference method, no significant difference was observed at the 95% confidence level. A relative standard deviation of ca  2% (n=9 ) was obtained when processing a typical red wine sample containing 7.3 gl -1 total acidity expressed as tartaric acid.