Effects of estradiol benzoate and trenbolone acetate, alone or in combination at dose levels present in Synovex Choice, on performance by feedlot heifers.

Trials were conducted with beef heifers at 4 sites to evaluate feedlot performance and carcass characteristics in response to implants containing 14 mg estradiol benzoate and 100 mg trenbolone acetate (EB/TBA; Synovex Choice, Zoetis LLC, New York, NY), 14 mg estradiol benzoate (EB), 100 mg trenbolone acetate (TBA), or a sham-implanted control (SC). The study design at each site was a randomized complete block with 12 blocks and 4 treatments. Blocks of cattle at each site were harvested in commercial abattoirs when masked personnel estimated at least 60% of animals would yield carcasses with USDA quality grades of Choice or Prime. Data were pooled across sites for statistical analysis. Initial BW averaged 374 kg, and days on feed ranged from 98 to 126 d (mean 112 d). Heifers implanted with EB/TBA, EB, and TBA had greater ADG and G:F (P < 0.05) than SC; ADG and G:F were greater for EB/TBA than EB or TBA (P < 0.05). Heifers treated with TBA had greater G:F than EB (P < 0.05). Feed intake was not affected by treatments. Mean HCW and LM area for EB/TBA were greater than for other treatments (P < 0.05). Mean HCW for TBA was greater than SC (P < 0.05) but not different from EB. Mean LM area for EB and TBA were greater than SC (P < 0.05) but not different from each other. There were no treatment differences (P > 0.05) for KPH, 12th-rib fat thickness, or yield grade. Dressing percent was greater for EB/TBA than SC (P < 0.05) but not different from EB or TBA. Marbling score was decreased by EB/TBA (P < 0.05) compared with other treatments, but no other differences were noted. Despite the effect of EB/TBA on marbling scores, there were no significant (P > 0.05) treatment differences on proportions of carcasses with quality grades ≥ Choice vs. < Choice. With respect to ADG and G:F, implants containing EB, TBA, or EB/TBA produced improved responses over SC. Furthermore, EB/TBA induced greater ADG and G:F responses than EB and TBA. Results confirmed that EB and TBA have additive effects, as evidenced by the observation that calves implanted with EB/TBA had significantly greater ADG and G:F than heifers implanted with either EB or TBA alone or compared with SC heifers.

Efficacy of moxidectin 0.5% pour-on against swine nematodes.

Forty pigs with induced infections of Ascaris suum, Trichuris suis, Metastrongylus spp., Oesophagostomum dentatum and O. quadrispinulatum were assigned to five-dose groups of moxidectin 0.5% pour-on with eight pigs per dose group. The doses were: moxidectin, 0 (vehicle control), 0.75, 1.00, 1.25, and 1.50 mg/kg(-1) body weight. Worm egg counts (EPG) were made from fecal samples collected on Day 2 pretreatment and on Day 14 or 15 post-treatment. Animals were ranked according to the descending order of A. suum egg counts made on Day 2 and blocked in groups of five. Pigs in blocked groups were assigned randomly to each of the five dose groups. Treatment doses were calculated on the basis of weights taken on Day 1 and were administered topically from the neck to the base of the tail. Pigs were housed by pairs in individual pens provided with self-feeders and automatic waterers. Necropsies were performed on equal numbers of pigs from each treatment group on days 14 and 15 post-treatment. Adult and larval worms were collected, identified and counted by standard parasitological techniques. All counts were transformed by Y=log10 (count+1) transformation prior to analysis. A two-way analysis of variance was conducted and treatment effect was tested for significance at the 5% level. Efficacies based on geometric means and optimal doses were as follows: Ascaris suum, 98.3% at 1.25; Metastrongylus spp., 100% at 0.75; Oesophagostomum quadrispinulatum, 100% at 1.50; and Trichuris suis, 93.5% at 0.75. Efficacy for O. dentatum was from 81.3% to 100%; however, the average number of O. dentatum (30) was too small for significance. Two species of lungworms were present, Metastrongylus apri and M. pudendotectus but they were not speciated at necropsy. As reported for several anthelmintics, the efficacy of moxidectin was variable for Trichuris. The highest efficacy was in the 0.75 dose group with six pigs harboring a few or no worms. The lowest efficacy was in the 1.25 group with only two pigs harboring a few or no worms.

Quantitative evaluation by computer-based video densitometry of film response to different isotopes and fluorographic treatments.

Previous investigations of fluorographic methods have generally reported the minimum level of radioactivity that can be detected for a given length of exposure or the amount of radioactivity needed to reach a given optical density value. Even when the full characteristic curve is given, comparisons with other published values are difficult or, if different lengths of exposures are used, impossible. Computer-based video densitometry was used to evaluate different fluorographic methods. Sections of polyacrylamide gels with uniform distributions of either 35S or 125I radioactivity were embedded with different fluors and used to expose X-ray film for various lengths of time. Due to its compatibility with algorithms used in densitometry, the effectiveness of various treatments was evaluated by fitting relevant parameters to a modified Hill-type equation. The two parameters that were affected by treatments were the amount of radioactivity needed to half-saturate the film (ED50, or the midpoint) and the slope at the midpoint. The relationship between length of exposure and film density was investigated. Since the ED50 values for both 35S and 125I were found to vary in a linear fashion with respect to 1/time, one can determine the ED50 for lengths of exposure not reported. A unique feature of this method of evaluating effectiveness of different treatments, therefore, is that it is possible to compare films that were exposed for different lengths of time. The method of presenting data used here overcomes many of the difficulties in comparing different fluorographic and film treatments, is compatible with the needs of computer-based densitometry, and is suggested as a useful way in which to present the relationship among isotopes, fluors, and films.

A comparison of fluorographic methods for the detection of 35S-labeled proteins in polyacrylamide gels.

Eight different methods of fluorographic enhancement of sensitivity to 35S decay after gel electrophoresis were compared. Using Kodak X-Omat AR X-ray film, we found that some fluors were about equivalent to 2,5-diphenyloxazole/dimethyl sulfoxide embedding, whereas several other fluors were not quite as effective, but still were significantly more sensitive than control autoradiography. The most sensitive procedures can yield a detectable darkening of film with less than 1 dpm/mm2 of 35S after a 1-week exposure.

Ligand binding specificity of a neutral L-amino acid olfactory receptor.

1. The ligand binding specificity of the L-[3H]alanine binding site was investigated in isolated cilia preparations from the olfactory epithelium of channel catfish (Ictalurus punctatus) by competitive binding experiments. 2. Approximately 45 amino acids, derivatives and enantiomers were tested for the ability to compete with radiolabeled L-alanine for common binding sites. 3. Acidic and basic L-amino acids and imino acids did not compete as effectively as L-alanine for the receptor, while long-chain neutral ligands were only partially effective inhibitors of L-alanine binding. 4. D-Alanine and L-alanine derivatives with substituted alpha-amino or carboxyl groups exhibited decreased ability to compete for the receptor, paralleling their lower neurophysiological potency. 5. In combination, the ligand binding results were consistent with previous electrophysiological data in catfish, and suggest the presence of an olfactory receptor site that selectively recognizes short-chain neutral amino acids.

Destinations of some fast-transported proteins in sensory neurons of bullfrog sciatic nerve.

Many characteristics of proteins that are fast axonally transported have been described, but the destinations of most within the neuron remain unknown. We have studied the destinations of some fast-transported proteins in sensory neurons of the bullfrog sciatic nerve, specifically to determine which may be deposited in axons and which may be destined for more distal, possibly terminal, areas. Dorsal root ganglia were pulse-labeled with [35S]methionine in vitro, following which they were separated from the sciatic nerve. After additional periods of transport, radioactive proteins from two areas of the nerve were separated by two-dimensional polyacrylamide gel electrophoresis and used to develop x-ray film. The first area contained the wavefront of transported radioactivity (wavefront region), whereas the second area was taken from nerve through which the wavefront had already passed (plateau region). The amount of radioactivity in certain fast-transported protein species from each area was determined by computer analysis of digitized video images of fluorographs. Certain proteins were preferentially left behind the wavefront and, therefore, may supply axon and possibly other nerve components, whereas other proteins were found almost exclusively in the wavefront and, hence, may supply more distal, possibly terminal, areas.

Proteins in fast axonal transport are differentially transported in branches of sensory nerves.

Radioactively labeled, fast-transported proteins were collected at ligatures placed on peripheral and central branches of spinal sensory nerves of the bullfrog. In agreement with previous studies, we found that the same species of proteins were transported down each branch. For each protein species analyzed we have measured the amount of radioactivity reaching each ligature, and calculated the ratio of radioactivity reaching the peripheral ligature to that reaching the central ligature. Not all protein species have the same ratio. This suggests that there may be differential transport of fast-transported proteins in axonal branches.