Zinc supplementation strategies in feedlot heifers receiving an extended-release implant or an aggressive re-implant program

Two hundred eight Angus-crossbred heifers (291 ± 23 kg) from four sources were used in a randomized complete block design. The objective of the study was to determine the effects of implant strategy and Zn supplementation on performance, carcass characteristics, muscle fiber diameter, and mineral status of heifers. Heifers were assigned to a 2 × 2 factorial study for 168 d, and factors included Zn and implant (IMP). Heifers were supplemented Zn (mg/kg dry matter [DM]; ZnSO₄) at national (30; NRC) or industry (100; IND) recommendations. Implant strategies (Merck Animal Health, Madison, NJ) included extended-release Revalor-XH on day 0 (REV-XH; 20 mg estradiol + 200 mg trenbolone acetate) containing four uncoated pellets and six coated pellets or the uncoated implant Revalor-200 on day 0 and again on day 91 (REV-200; 20 mg estradiol + 200 mg trenbolone acetate). Heifers were blocked by weight within source to pens of five or six heifers per pen (nine pens per treatment). A corn silage-based diet was fed during the growing period (days 0–55) followed by transition to a corn-based finishing diet. Weights were taken consecutively on days −1/0, 55/56, and 167/168. Liver and muscle from the longissimus thoracis were collected from one heifer per pen on days −5, 14, 105, and 164. Data were analyzed via Mixed Procedure of SAS. Average daily gain (ADG) and liver mineral used Period as the repeated effect. Corresponding to periods of high hormone payout from each implant, days 0–28 and 91–120 ADG were greatest for REV-200, whereas REV-XH numerically peaked during days 56–91 (IMP × Period; P = 0.02). Day 91 IND body weight tended to be heavier (P = 0.06) and day 120 body weight was heavier (P = 0.05) than NRC heifers. No effect of Zn or IMP on final body weight was observed (P ≥ 0.21). Muscle fiber cross-sectional diameter on day 164 was greater (P = 0.05) in IND than NRC. Liver Mn concentrations decreased by day 14 regardless of implant, though days 105 and 164 concentrations were lesser for REV-200 than REV-XH (IMP × Period; P = 0.02). No effects of Zn, IMP, or the interaction were observed for carcass-adjusted gain to feed, days 0–168 DM intake, hot carcass weight, or ribeye area (P ≥ 0.11). The nominal differences in performance between implant strategies suggest that extended-release implants may be an effective implant strategy to replace re-implant programs in heifers, whereas the improved performance of heifers fed IND vs. NRC during times of peak hormone payout suggests a role for Zn in periods of rapid growth.     

Effect of nematode burden as assessed by means of faecal egg counts on body condition in goats farmed under resource-poor conditions in South Africa

A longitudinal study was conducted of the nematode faecal egg counts (FECs) and body condition scores (BCSs) of goats of resource-poor farmers at Rust de Winter, Gauteng Province, Impendle, KwaZulu-Natal Province, and Kraaipan, North-West Province, South Africa. Periods of higher FECs occurred from December/January to March/April at Rust de Winter and at Impendle and from January to March at Kraaipan. Seasonal variations in body condition were evident in the goats at Impendle with the animals showing lower BCSs from June to October. The goats at Rust de Winter and at Kraaipan did not show clear seasonal variations, although the goats at Rust de Winter showed lower BCSs from mid-July to early December. The BCSs for Rust de Winter where the animals were grazed on a private farm were generally higher than those of the other sites, where communal grazing is practised.     

Characterization of Clostridium difficile isolates from foals with diarrhea: 28 cases (1993-1997)

OBJECTIVE: To determine molecular characteristics of Clostridium difficile isolates from foals with diarrhea and identify clinical abnormalities in affected foals. DESIGN: Retrospective study. ANIMALS: 28 foals with C difficile-associated diarrhea. PROCEDURE: Toxigenicity, molecular fingerprinting, and antibiotic susceptibility patterns were determined. Information on signalment, clinical findings, results of clinicopathologic testing, whether antimicrobials had been administered prior to development of diarrhea, and outcome was obtained from the medical records. RESULTS: Twenty-three (82%) foals survived. Toxin A and B gene sequences were detected in isolates from 24 of 27 foals, whereas the toxin B gene alone was detected in the isolate from 1 foal. Results of an ELISA for toxin A were positive for fecal samples from only 8 of 20 (40%) foals. Ten of 23 (43%) isolates were resistant to metronidazole. Molecular fingerprinting revealed marked heterogeneity among isolates, except for the metronidazole-resistant isolates. Sixteen foals had tachypnea. Hematologic abnormalities were indicative of inflammation. Common serum biochemical abnormalities included metabolic acidosis, hyponatremia, hypocalcemia, azotemia, hypoproteinemia, hyperglycemia, and high enzyme activities. Passive transfer of maternal antibodies was adequate in all 12 foals evaluated. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that a large percentage of C difficile isolates from foals with diarrhea will have the toxin A and B gene sequences. Because of the possibility that isolates will be resistant to metronidazole, susceptibility testing is warranted. Clostridium difficile isolates from foals may have a substantial amount of molecular heterogeneity. Clinical and hematologic findings in affected foals are similar to those for foals with diarrhea caused by other pathogens.     

Bacterial colonization affects early organ and gastrointestinal growth in the neonate

Enteral nutrition coupled with bacterial colonization has been shown to have major functional and developmental effects during the postnatal period of neonates. In this study, we developed a highly sensitive premature pig model to elucidate the specific developmental impact of initial bacterial colonization on premature neonates by comparing germ-free and conventionally reared pigs. Thirty-eight preterm pigs (93% gestation) were delivered via caesarean section and reared in either germ-free or conventional isolators for 40–48 h. Pigs were fed either infant milk formula or sow's colostrum. Enteral feeding for two days had trophic effects on gastrointestinal weights, particularly for pancreas, stomach and small intestine (SI). The absence of bacteria in formula fed pigs resulted in a mucosa that appeared more robust and had higher weights for both SI and pancreas, compared to conventional formula fed pigs (P < 0.05). Colostrum fed pigs also had markedly increased mucosal SI proportions, lung and spleen weights compared to conventional formula fed pigs. Colostrum fed pigs and germ-free pigs were similar although stomach, pancreas and distal SI weights were highest for germ-free pigs. The results demonstrate that the initial bacterial colonization interacts with diet to modulate the early neonatal organ development, particularly of the GIT.     

Matrix metalloproteinase activity in tumor, stromal tissue, and serum from cats with malignancies

Matrix metalloproteinases (MMPs) are enzymes that play key roles in angiogenesis, tumor invasion, and metastasis in a wide variety of species. The purpose of this study was to evaluate pro and active MMP 2 and 9 concentrations in tumor, normal stromal tissue, and serum from tumor-bearing cats. We hypothesized that serum concentrations of pro and active forms of MMPs 2 and 9 would be predictive of MMP concentrations in tumor tissue and that these MMP concentrations would correlate with the histopathologic grade of the malignancies. Pro and active forms of MMPs 2 and 9 were determined by gelatin zymography and subsequent computerized densitometry from tumor and nearby stromal tissue and serum from 49 cats with various malignancies. The serum concentrations of MMPs from these tumor-bearing cats were compared with serum concentrations of MMPs from 44 normal cats of similar age and gender. Measurable concentrations of MMPs 2 and 9 were found within tumor, stromal, and serum samples. Mean concentrations of total pro and active MMPs 2 and 9 within tumor tissue were significantly higher (P values <.0001, .0031, <.001, and .0064, respectively) when compared with stromal tissue from the same animals. Serum MMP concentrations from tumor-bearing cats were higher than those from normal cats. Poor correlation was found between serum MMP concentrations and tissue MMP concentrations of increasing histologic grades of malignancies.     

Bartonella species detection in captive, stranded and free-ranging cetaceans

We present prevalence of Bartonella spp. for multiple cohorts of wild and captive cetaceans. One hundred and six cetaceans including 86 bottlenose dolphins (71 free-ranging, 14 captive in a facility with a dolphin experiencing debility of unknown origin, 1 stranded), 11 striped dolphins, 4 harbor porpoises, 3 Risso's dolphins, 1 dwarf sperm whale and 1 pygmy sperm whale (all stranded) were sampled. Whole blood (n = 95 live animals) and tissues (n = 15 freshly dead animals) were screened by PCR (n = 106 animals), PCR of enrichment cultures (n = 50 animals), and subcultures (n = 50 animals). Bartonella spp. were detected from 17 cetaceans, including 12 by direct extraction PCR of blood or tissues, 6 by PCR of enrichment cultures, and 4 by subculture isolation. Bartonella spp. were more commonly detected from the captive (6/14, 43%) than from free-ranging (2/71, 2.8%) bottlenose dolphins, and were commonly detected from the stranded animals (9/21, 43%; 3/11 striped dolphins, 3/4 harbor porpoises, 2/3 Risso's dolphins, 1/1 pygmy sperm whale, 0/1 dwarf sperm whale, 0/1 bottlenose dolphin). Sequencing identified a Bartonella spp. most similar to B. henselae San Antonio 2 in eight cases (4 bottlenose dolphins, 2 striped dolphins, 2 harbor porpoises), B. henselae Houston 1 in three cases (2 Risso's dolphins, 1 harbor porpoise), and untyped in six cases (4 bottlenose dolphins, 1 striped dolphin, 1 pygmy sperm whale). Although disease causation has not been established, Bartonella species were detected more commonly from cetaceans that were overtly debilitated or were cohabiting in captivity with a debilitated animal than from free-ranging animals. The detection of Bartonella spp. from cetaceans may be of pathophysiological concern.     

Quantification of bioavailable chlortetracycline in pig feces using a bacterial whole-cell biosensor

Bacterial whole-cell biosensors were used to measure the concentration of chlortetracycline (CTC) in the feces of pigs. In this study, the Escherichia coli biosensor used has a detection limit of 0.03 mg/kg CTC in pig feces. The tetracycline concentration was correlated with the appearance and maintenance of fecal coliform bacteria resistant to tetracycline. Initially, large quantities of water-extractable CTC were excreted from the pigs and measurable amounts were detected even at 30 days after treatment cessation. This led to a sharp rise in the number of tetracycline resistant coliform bacteria in the feces, to within the same order of magnitude as the total coliform count. The high level of tetracycline resistance was maintained in spite of the declining concentration of tetracycline.