The effect of polychlorinated biphenyls on the vitamin A, vitamin E, and ascorbic acid status in young pigs

Admixture for 14 to 26 days of concentrations between 1 mg/kg to 250 mg/kg of polychlorinated biphenyls, Delor 103, 105, and 106 (Chemko, Strázeke) to ready-mixed feedstuffs was studied in 5 experiments for its effects on 71 piglets and store pigs. Neither growth nor general health were in any way impaired. Polychlorinated biphenyls produced different effects upon vitamin A, vitamin E, and ascorbic acid levels in different organs. Vitamin A concentrations in blood serum, for example were reduced by 100 mg/kg and 250 mg/kg of Delor 105 as well as by 250 mg/kg of Delor 103. Liver levels were not significantly depressed. No changes were recordable from vitamin E levels in blood serum and liver. Ascorbic acid saturation of the organism was positively affected. Its concentrations and overall levels in the liver in all experimental groups were higher than those in all controls. Significant rise of ascorbic acid concentrations in blood serum, urine, and kidneys occurred merely in response to 100 mg/kg and 250 mg/kg of Delor 105 as well as to 250 mg/kg of Delor 103. No adverse effect of tissue-borne residues of polychlorinated biphenyls on the status of administered vitamins was recordable 1 to 4 months after termination of experimental supply. Feed intake with 1 mg/kg of Delor 105, which was equivalent to increased natural contamination, did not cause any negative phenomena in any of the probands.     

Amoxycillin as an alternative to dihydrostreptomycin sulphate for treating cattle infected with Leptospira borgpetersenii serovar hardjo

Objective To assess the effect of amoxycillin treatment on urinary excretion of leptospires from cattle infected with Leptospira borgpetersenii serovar hardjo .
Design A chemotherapy trial with controls.
Procedure Fourteen heifers serologically negative to L hardjo were inoculated with L hardjo via the conjunctival route and assessed for evidence of infection by serological, fluorescent antibody and microbiological tests. Two injections (48 h apart) of amoxycillin at a dose of 15 mg/kg were administered intramuscularly to seven heifers 6.5 weeks after infection; the remaining heifers acted as untreated controls. Later, these seven control group heifers were treated with a single dose of amoxycillin (15 mg/kg). Samples of urine were collected before and after amoxycillin treatments; kidneys were collected at slaughter, and examined by fluorescent antibody test and microbiological culture.
Results Leptospires were isolated from the urine of 11 of 14 heifers inoculated with L hardjo . After treatment of six of these with two injections of amoxycillin, leptospires were not isolated. Of the controls, four of the five initially leptospiruric heifers continued to shed leptospires; after a single injection of amoxycillin, no leptospires were detected in the kidneys of these four.
Conclusion Amoxycillin may be an acceptable alternative to dihydrostreptomycin sulphate for the treatment of cattle infected with L hardjo .     

Fetal and neonatal goiter in cynomolgus monkeys following administration of the antithyroid drug thiamazole at high doses to dams during pregnancy

To evaluate morphologic alterations in the thyroid gland in the second generation in cynomolgus monkeys, pregnant dams were exposed to high doses of thiamazole. In Experiment A, dams received thiamazole intragastrically via a nasogastric catheter from gestation day (GD) 50 to GD 150 or on the day before delivery. Initially, the dose level was 20 mg/kg/day (10 mg/kg twice daily); however, the dose level was subsequently decreased to 5 mg/kg/day (2.5 mg/kg twice daily), since deteriorated general conditions were observed in two dams. Six out of seven neonates died on the day of birth. The cause of neonatal death was tracheal compression and suffocation from goiter. The transplacental exposure to thiamazole affected the fetal thyroid glands and induced goiter in all neonates. The surviving neonate was necropsied 767 days after discontinuation of thiamazole exposure and showed reversibility of the induced changes. In Experiment B, dams were intragastrically administered thiamazole at 5 mg/kg/day (2.5 mg/kg twice daily) for treatment periods from GDs 51 to 70, 71 to 90, 91 to 110, 111 to 130 and 131 to 150. All fetuses showed enlarged thyroid glands but were viable. Histopathologically, hypertrophy and/or hyperplastic appearance of the follicular epithelium of the thyroid gland was observed at the end of each treatment period. The most active appearance of the follicular epithelium, consisting of crowded pedunculated structure, was demonstrated at end of the treatment period from GD 131 to 150. This is the first report on the morphology of fetal and neonatal goiter in the cynomolgus monkey.     

The effect of lithium chloride on renal structure and sodium-potassium-adenosine triphosphatase activity in dogs

Lithium chloride was given intraperitoneally to dogs at a dosage of 125 mg/kg body weight for three days. Kidneys were removed for morphologic examination and quantitation of sodium-potassium-adenosine triphosphatase (Na-K-ATPase) activities in cortical and medullary tissue. Light microscopy showed no changes in the kidneys, but cytoplasmic vacuolation and dilatation of the cisternae of the endoplasmic reticulum were seen ultrastructurally in the epithelial cells of the distal tubule and cortical and medullary collecting ducts. Mean cortical Na-K-ATPase activity was 1.49 +/- 0.25 and 1.70 +/- 0.31 mumoles inorganic phosphate/mg protein/hour in control and experimental groups respectively. Mean medullary Na-K-ATPase activity was 4.71 +/- 0.41 and 5.01 +/- 0.47 mumoles inorganic phosphate/mg protein/hour in control and experimental groups respectively. It was concluded that lithium produced morphologic changes in the distal nephron, but had no effect on renal Na-K-ATPase activity.     

Evaluation of the contamination degree of roe-deer with cadmium and polychlorinated biphenyls in Warmia and Mazury district

The results of investigations concerning degree the contamination degree with cadmium and polychlorinated biphenyls (PCB's) of roe-deer organs hunt in seven selected areas of Warmia and Mazury voivodship are presented. The highest mean cadmium content in the organs investigated was found in the samples from G?ebock area (liver - 0.0576 mg/kg, kidney - 3.351 mg/kg) and the lowest one was observed in the samples from Pisz area (liver - 0.181 mg/kg, kidneys - 1.653 mg/kg). Mean level of polychlorinated biphenyls residues in the roe-deer fat from Warmia and Mazury district was 0.004 mg/kg. The highest PCB's mean concentration was found in the roe-deer fat samples from Milomlyn area (0.008 mg/kg), and the lowest one in those from G?ebock area (0.002 mg/kg). Presented levels of investigated xenobiotics do not make at present (except cadmium in kidney) any toxicological threats for venison consumers in Warmia and Mazury district.     

Acute airsacculitis in turkeys inoculated with phorbol myristate acetate

Phorbol myristate acetate (PMA), which induces acute pulmonary injury in mammals, induced acute airsacculitis in turkeys after intra-airsac inoculation of 0.1 mg/kg. Grossly, air sacs contained multifocal to diffuse hemorrhage and edema at postinoculation hours (PIH) 3 and 6. Microscopically, there was multifocal congestion and small thrombocyte aggregates within small blood vessels by PIH 0.5, with a few vessels containing small numbers of marginating heterophils. By PIH 1.5, thrombocyte aggregates were larger and more numerous, and moderate numbers of heterophils were located perivascularly. Erythrocytes and proteinaceous fluid were in air sac interstitium. By PIH 3 and 6, hemorrhage and exudation of proteinaceous fluid had increased, in some instances severely distending the air sac. Ultrastructurally, changes resulting from PMA-induced injury were thrombocyte aggregation and degeneration, air sac epithelial cell vacuolation with separation of interdigitating cell processes, and endothelial cell vacuolar degeneration with loss of vascular integrity. Air sac lavage fluids had mildly increased total cell counts by PIH 1.5, but values returned to baseline by the end of the experiment, indicating lack of cell exudation into the air sac lumen. Circulating leukocyte changes included transient lymphopenia at PIH 3 and marked heterophilia at PIH 6. These results indicate that thrombocytes and/or heterophils are central to the pathogenesis of injury induced in air sacs by PMA and that the air sac responds differently to PMA than to pathogenic bacteria.     

Efficacy of actaplanin fed on a twice-weekly basis to grazing stocker heifers

Brahman (16), Brangus (32) and Simmental X Brahman (16) open heifers were assigned to four treatment levels and two body weight categories. The weight categories were light (250 kg) and heavy (306 kg). Treatment groups were 0, 600, 900 and 1,200 mg actaplanin.head-1.feeding-1 with feeding only on Monday and Friday. Heifers were group-fed .91 kg/head of supplement (95% soybean meal: 5% molasses) containing actaplanin. Heifers grazed eight Coastal bermudagrass pastures throughout the experiment (July 29 to November 15, 1982). After 75 d on experiment, an additional 1.36 kg of a commercial 14% crude protein supplement was fed on the days that actaplanin was not fed. All heifers were weighted and rotated among pastures at 14-d intervals (last weight period was 11 d) as an attempt to equalize forage availability among groups. Over the entire experiment (109 d), light-weight heifers that were fed actaplanin responded (P less than .01) with greater average daily gain (ADG; .37, .35, .21 kg/d; 600, 900, 1,200) compared with controls (0 mg; .18 kg/d). A trend in response (P less than .10) to actaplanin feeding occurred for heavy-weight heifers (.23, .38, .34 kg/d; 600, 900, 1,200 mg vs controls (.22 kg/d). For light-weight heifers, ADG decreased lineraly (P less than .01) as actaplanin increased from 600 to 1,200 mg, while ADG for heavy-weight heifers increased linearly (P less than .10).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of isotonic and hypotonic lactated ringer's solutions with dextrose intravenously administered to dehydrated heifers

To determine the effects of rapid infusion of essential fluids in a volume of hypotonic lactated Ringer's solution, the central venous pressure (CVP) and acid-base equilibrium were investigated in to mildly dehydrated heifers. Mild dehydration was induced in 9 Holstein heifers by withholding food and water until 7.0+/-5.7% of plasma volume had been lost. The heifers were randomly assigned to the ILG (lactated Ringer's + 5% dextrose), HLG (1/2 lactated Ringer's + 2.2% dextrose) or HRG (1/2 Ringer's + 2.5% dextrose) groups with 3 heifers in each group. Heifers received 30 ml/kg of one of the fluids, at a flow rate of 20 ml/kg/hr. The rapid intravenous (IV) infusions of HLG and HRG used in this study were found to be safe and effective in increasing plasma volume without increasing CVP, even though the infusion was given to the jugular vein at a dosage of 30 ml/kg. However, ILG infusion induced progressive increases in CVP, reaching 9.0+/-2.0 mmHg. No clinical signs, such as moist rales on auscultation, moist cough, jugular vein congestion, ophthalmoptosis, salivation or arrhythmia, were observed throughout the fluid infusion. The relative changes in base excess (rBE) for the ILG and HRG groups were significantly decreased until the end of fluid infusion. As for the HLG group, rBE slightly decreased until the end of the fluid infusion. Then the values significantly increased and exceeded the pre-infusion value at the end of the experiment. While IV infusion of HLG inhibited acidification caused by dilution, HRG infusion induced diluted acidification. It is suggested that HLG infusion should be examined as a treatment for cattle with dehydration and moderate metabolic acidosis, since rapid infusion of HLG may be more beneficial for rehydrating cattle with metabolic acidosis than current treatment.     

肉鸡实验性镉中毒的病理学研究

用3日龄雏鸡150只，作急性和亚急性镉中毒病理学观察，急性毒性的LD50为84．48mg/kg体重。1／10，1／20，1／30，1／40LD50和基础组作亚急性实验，实验期6周，死亡和存活鸡之比分别为4／12，3／12，3／12，3／12和0／12。死亡鸡的主要病变为肺充血、出血及炎症，肝变性及肝周炎，心肌变性及心外膜炎以及肠道卡他等。电镜检查亚急性存活病例，主要肝、心、肾细胞内的线粒体减少及萎缩，肝内质网增生、断裂，肾小球基底膜节段性增厚。亚急性试验鸡的肝和肌肉中镉含量极显著差异高于对照组（P＜0．01），而肝中铁含量试验组则极显著低于对照组(P＜0．01）。     

Estimated copper requirements of angus and simmental heifers

In Exp. 1, Simmental (n = 21) and Angus (n = 21) heifers, approximately 9 mo of age, were used in a 160-d study to determine the effect of dietary Cu on growth and Cu status. Two- or three-yr-old first-calf heifers (21 Angus and 21 Simmental) entering into their last trimester of pregnancy were used in Exp. 2 to estimate Cu requirements of the two breeds during gestation and early lactation. Treatments in both studies consisted of 0 (control), 7, or 14 mg of supplemental Cu (as CuSO4)/kg of DM. The control corn silage-based diets contained 6.4 and 4.4 mg of Cu/kg of DM in Exp. 1 and 2, respectively, and 1.2 mg of Mo/kg. Dietary Cu did not affect performance in either breed in Exp. 1. Copper supplementation generally did not affect plasma Cu concentrations in Angus heifers, but increased (P < 0.05) plasma Cu in Simmental heifers from d 37 until the end of Exp. 1. Final liver Cu concentrations were lower (P < 0.05) than initial concentrations in control Angus and Simmental heifers; however, liver Cu increased (P < 0.01) in Cu-supplemented heifers. In Exp. 2, Cu supplementation of the control diet increased (P < 0.05) plasma Cu during gestation and greatly increased (P < 0.01) liver Cu in both breeds. Calves born to cows not supplemented with Cu also had lower plasma Cu concentrations than Cu-supplemented calves by 73 d of age. In both studies, control Simmental heifers had lower (P < 0.05) plasma Cu concentrations than Angus on most sampling dates. When Cu was supplemented at 7 or 14 mg/kg of DM,few differences in plasma Cu concentrations were observed between breeds. Results suggest that Angus heifers have a lower minimal Cu requirement than Simmental. Based on liver Cu, the control diets containing 4.4 or 6.4 mg of Cu/kg of DM did not meet the Cu requirement of either breed during gestation and lactation or growth. Addition of 7 mg of Cu/kg of DM to the control diets met Cu requirements of both breeds.     

Experimental polychlorinated biphenyl toxicosis in germfree pigs.

The effects of polychlorinated biphenyls were studied in eight germfree pigs. Beginning at fourteen days of age, two pigs each were fed daily 12.5, 25, 50 and 100 mg/kg body weight of polychlorinated biphenyls as Aroclor 1254. Three germfree pigs were negative controls. Clinically the treated pigs had inappetance, a hemorrhagic diarrhea, erythema of the nose and the anus, retarded growth, distended abdomen and at the higher dose levels, incoordination and coma followed by death. Deaths occurred in 11 to 35 days after exposure. At necropsy, the piglets exhibited grossly enlarged mottled liver, erosions of the gastric mucosa, hemorrhages through the mesentery and the intestinal wall, a fibrinous pericarditis, a hypoplastic thymus and congested swollen thyroid glands. The histopathological lesions included hepatic centrolobular necrosis, interstitial myocarditis, endocarditis, myopathy of the muscles, gastric erosions and colitis. All of the organs examined for polychlorinated biphenyls had elevated residue levels which were particularly high in the fat, liver, psoas muscle, brain and kidney and were higher than has been reported in conventional pigs fed approximately equal concentrations of polychlorinated biphenyls. The severity of clinical signs, pathological changes and tissue concentrations were directly related to the dose administered and were more pronounced in the germfree pigs than has been described in conventional pigs.     

Sequential observation of 2,6-dimethylaniline-induced nasal lesions in a rat two-stage nasal carcinogenesis model after initiation with N-bis(2-hydroxypropyl) nitrosamine

Male F344 rats received diet containing 3,000 ppm 2,6-dimethylaniline (DMA) after initiation with a single subcutaneous injection of 2,400 mg/kg of N-bis(2-hydroxypropyl)nitrosamine (DHPN), and histological and electron microscopic examinations of the nasal cavity were performed at 4, 13, 26 and 52 weeks to examine sequential changes induced by DMA. Severe atrophy of Bowman's glands and epithelial disarrangement were apparent from week 4, followed by dilatation and/or proliferation of Bowman's glands, degeneration of epithelial cells, and proliferation of undifferentiated epithelial cells from week 13. Focal glandular hyperplasias, dysplastic foci, and adenomas were observed from week 26, and carcinomas at 52 week. These nasal lesions were mostly evident in the olfactory mucosa in the nasal cavity, and their severity and/or incidences, other than atrophy of Bowman's glands, increased with the treatment period. Electron microscopically, carcinoma cells demonstrated desmosomes, dense secretory granules identical to those in normal Bowman's glands, a basement membrane, and microvilli. These results suggest that Bowman's glands are the target of DMA, giving rise to nasal carcinomas after DHPN-initiation.     

THE NON-CARDIAC DISTRIBUTION OF 99mTC-METHOXY-ISOBUTYL-ISONITRILE (SESTAMIBI) IN NORMAL BEAGLES

Technetium-99m methoxy-isobutyl-isonitrile (sestamibi) is a radiophartnaceutical used for the evaluation of myocardial perfusion. Increased uptake of sestamibi has also been documented in tumors. The objective of this study was to document the extracardiac biodistribution of ^99mTc sestamibi in the normal dog. Nine normal beagles were given 0.35 mCi/kg ^99mTc sestamibi intravenously, and 60 second images were made of the entire body at 1 hour post injection. A defined distribution pattern was recognized, with good visualization of the heart, liver, gallbladder, small intestine, kidneys, urinary bladder, popliteal lymph nodes, parotid salivary glands and zygomatic salivary glands. Splenic uptake was not seen.
Target to background ratios were calculated for all the regions listed, using background regions-of-interest with the smallest coefficient of variance for the denominator. The mean, range and standard deviation of these ratios are given.     

Assessment of melamine and cyanuric acid toxicity in cats.

The major pet food recall associated with acute renal failure in dogs and cats focused initially on melamine as the suspect toxicant. In the course of the investigation, cyanuric acid was identified in addition to melamine in the offending food. The purpose of this study was to characterize the toxicity potential of melamine, cyanuric acid, and a combination of melamine and cyanuric acid in cats. In this pilot study, melamine was added to the diet of 2 cats at 0.5% and 1%, respectively. Cyanuric acid was added to the diet of 1 cat at increasing doses of 0.2%, 0.5%, and 1% over the course of 10 days. Melamine and cyanuric acid were administered together at 0%, 0.2%, 0.5%, and 1% to 1 cat per dose group. No effect on renal function was observed in cats fed with melamine or cyanuric acid alone. Cats dosed with a combination were euthanized at 48 hours after dosing because of acute renal failure. Urine and touch impressions of kidneys from all cats dosed with the combination revealed the presence of fan-shaped, birefringent crystals. Histopathologic findings were limited to the kidneys and included crystals primarily within tubules of the distal nephron, severe renal interstitial edema, and hemorrhage at the corticomedullary junction. The kidneys contained estimated melamine concentrations of 496 to 734 mg/kg wet weight and estimated cyanuric acid concentrations of 487 to 690 mg/kg wet weight. The results demonstrate that the combination of melamine and cyanuric acid is responsible for acute renal failure in cats.     

Acute phase protein response during acute ruminal acidosis in cattle

The aim of the study was to describe the acute phase protein and leukocyte responses in dairy heifers during acute, oligofructose-induced ruminal acidosis. The study included 2 trials involving oral oligofructose overload (17 g/kg BW) to nonpregnant Danish Holstein heifers. Trial 1 included 12 heifers all receiving oligofructose, and the experiment consisted of a 3 day control period prior to overload and 9 days surveillance afterwards. Eight heifers were fed grass hay and 4 were fed barley silage. Trial 2 included 10 heifers receiving oligofructose, 4 were euthanized 24 h after overload and 6 were euthanized 72 h after overload. Six heifers received tap water as control treatment and were euthanized 72 or 96 h later. Sampling of blood was performed at 6–48 hour intervals. Samples were analyzed for serum amyloid A (SAA), haptoglobin, and fibrinogen, and total white blood cell counts (WBC) were performed.     

Effects of supplementing combinations of inorganic and complexed copper on performance and liver mineral status of beef heifers consuming antagonists.

Performance, immune response, and liver trace mineral status were measured in growing heifers supplemented with different copper (Cu) concentrations and sources when diets contained the Cu antagonists Mo, S, and Fe. Sixty Angus x Hereford heifers were managed in two groups for 112 d and were either individually fed diets and mineral treatments using individual feeding stalls (Stall) or pen-fed grass hay and individually supplemented mineral treatments (Pen). The basal diet of grass hay, rolled barley, and soybean meal was analyzed to contain 6 mg Cu/kg DM. The treatments consisted of 1) no supplemental Cu (Control); 2) 49 mg Cu/kg DM from Cu sulfate (i.e. approximately five times NRC recommendation for Cu from CuSO4) (5X-SO4); 3). 22 mg Cu/kg DM from CuSO4 (2X-SO4); 4). 22 mg Cu/kg DM from a combination of 50% CuSO4 and 50% Cu-amino acid complex (50-50); and 5). 22 mg Cu/kg DM from a combination of 25% CuSO4, 50% Cu-amino acid complex, and 25% Cu oxide (CuG) (25-50-25). All heifers were supplemented with the Cu antagonists Mo (10 mg/kg DM), S (2,900 mg/kg DM), and Fe (500 mg/kg DM). These diets resulted in dietary Cu:Mo ratios that averaged 0.5:1 for Control, 4.5:1 for the 5X-SO4, and 2.4:1 for 2X-SO4, 50-50, and 25-50-25. Rate and efficiencies of gain and cell-mediated immune function were not different (P > 0.10) among treatments. Data suggest supplements containing combinations of inorganic and complexed Cu interacted differently in the presence of Mo, S, and Fe. Heifers consuming the 25-50-25 supplement in the Stall group initially lost hepatic Cu rapidly but this loss slowed from d 50 to d 100 compared to the Control (P = 0.07), 50-50 (P < 0.05), and 2X-SO4 (P < 0.05) heifers and was similar (P > 0.10) to that in the 5X-SO4 heifers. In the Pen group, total hepatic Cu loss tended to be greater for 25-50-25 and 2X-SO4 compared to 5X-SO4 heifers (P = 0.09 and P = 0.06, respectively); Cu loss in the 50-50 heifers was similar (P > 0.10) to that in the 5X-SO4 heifers. This suggests that supplementing combinations of inorganic and amino acid-complexed Cu was as effective in limiting hepatic Cu loss during antagonism as was increasing dietary Cu levels to five times the NRC recommendation. A combination of 25% CuSO4 , 50% Cu-amino acid complex, and 25% CuO limited liver accumulation of Mo compared to supplements without CuO and could provide a strategic supplementation tool in limiting the systemic effects of Cu antagonism in beef cattle.     

Bovine corpus luteum regression and estrous response following treatment with alfaprostol

Two trials evaluated bovine corpus luteum (CL) regression and estrous response following treatment with alfaprostol (AP), a prostaglandin F2 alpha analogue. Expression of at least one estrous cycle (16 to 26 d) and a palpable mid-cycle CL were required prior to random assignment of females to receive 0, .38, .75, 1.50 or 2.25 mg AP/100 kg body weight. Alfaprostol was evaluated in Brahman cows and heifers that were treated on d 11 to 13 (trial 1) and in Simmental X Brahman-Hereford (crossbred) heifers that were treated on d 8 to 10 or d 11 to 13 of the estrous cycle (trial 2). In trial 1, Brahman heifers appeared to require a higher AP dose (greater than .38 mg/100 kg body weight) to elicit luteolysis and expression of estrus than Brahman cows. Alfaprostol treatment (greater than or equal to .75 mg/100 kg body weight) induced (P less than .0001) luteolysis followed by estrus in Brahman cows and heifers. In trial 2, crossbred heifers that received AP on d 8 to 10 appeared to require a higher dose of AP (greater than .38 mg/100 kg body weight) to elicit luteolysis and estrus than heifers that received AP on d 11 to 13 of the estrous cycle. Alfaprostol treatment greater than or equal to .75 mg/100 kg body weight on d 8 to 10 and d 11 to 13 of the estrous cycle induced (P less than .0001) luteolysis followed by estrus in crossbred heifers.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of tribasic copper chloride versus copper sulfate provided in corn-and molasses-based supplements on forage intake and copper status of beef heifers

The objective of this study was to investigate the effect of supplemental tribasic copper chloride (Cu(2)(OH(3))Cl; TBCC) vs. Cu sulfate (CuSO(4)) on Cu status and voluntary forage DMI in growing heifers. Two 90-d experiments were conducted using 48 non-pregnant, crossbred heifers (24 heifers/experiment; 355 +/- 10.7 and 309 +/- 9.9 kg for Exp. 1 and 2, respectively). In each experiment, 3 supplemental Cu treatments were randomly allocated to heifers in individual pens consisting of (1) 100 mg of Cu/d from CuSO(4), (2) 100 mg of Cu/d from TBCC, or (3) 0 mg of Cu/d. The 2 experiments differed by the form of supplement used to deliver the Cu treatments (corn- vs. molasses-based supplements for Exp. 1 and 2, respectively). Supplements were formulated and fed to provide equivalent amounts of CP and TDN daily but differed in their concentration of the Cu antagonists, Mo (0.70 vs. 1.44 mg/kg), Fe (113 vs. 189 mg/kg), and S (0.18 vs. 0.37%) for corn- and molasses-based supplements, respectively. All heifers were provided free-choice access to ground stargrass (Cynodon spp.) hay. Jugular blood and liver biopsy samples were collected on d 0, 30, 60, and 90 of each experiment. Heifer BW was collected on d 0 and 90. Heifer ADG was not affected by Cu treatment (average = 0.22 +/- 0.11 and 0.44 +/- 0.05 kg for Exp. 1 and 2, respectively; P > 0.20). In Exp. 1, heifers provided supplemental Cu, independent of source, had greater (P < 0.05) liver Cu concentrations on d 60 and 90 compared with heifers provided no supplemental Cu. In Exp. 2, average liver Cu concentrations were greater (P = 0.04) for heifers receiving supplemental Cu compared with heifers receiving no Cu; however, all treatments experienced a decrease in liver Cu concentration over the 90-d treatment period. Plasma ceruloplasmin concentrations did not differ in Exp. 1 (P = 0.83) but were greater (P = 0.04) in Exp. 2 for heifers receiving supplemental Cu compared with heifers receiving no Cu. In Exp. 1, voluntary forage DMI was greater (P < 0.05) for heifers provided supplemental Cu, independent of source, compared with heifers provided no Cu. In contrast, voluntary forage DMI was not affected (P > 0.10) by Cu supplementation in Exp. 2. These data imply that CuSO(4) and TBCC are of similar availability when offered to growing beef heifers in both corn- and molasses-based supplements. However, corn- and molasses-based supplements appear to affect Cu metabolism differently. These impacts may affect voluntary forage DMI in growing beef heifers.     

Effects of induced hypothyroidism or hyperthyroidism on growth and reproductive performance of Brahman heifers.

Prepubertal Brahman heifers (BW = 302 +/- 7.5 kg, body condition score [BCS] = 5.4 +/- .2, age = 498 +/- 3.4 d: SEM) were used to study the effects of thyroid function on growth and reproduction. Seven heifers were controls (C). Seven heifers were induced to become hypothyroid by ingestion of 4 mg/kg BW of 6-n-propyl-2-thiouracil (PTU). Seven heifers were induced to become hyperthyroid (T) by daily s.c. injections of triiodothyronine (T3, 1 mg/d). Treatments were administered for 84 d followed by an 84 d posttreatment period. Blood samples were obtained twice weekly via tail venipuncture for analysis of T3, thyroxine, and progesterone. The BW, BCS, and rectal temperature (RT) were recorded weekly. Estrus was monitored twice daily with the aid of a fertile bull equipped with a chin ball marker. Hyperthyroidism and hypothyroidism were successfully induced in T- and PTU- treated heifers, respectively. During the treatment period, PTU heifers gained the most BW and BCS (72.4 +/- 5.4 kg; .93 +/- .15 units), C heifers were intermediate (41.7 +/- 5.4 kg; .43 +/- .15 units), and T heifers gained the least (13.3 +/- 5.4 kg; -.36 +/- .15 units; P < .05). The RT also decreased (P < .05) in PTU heifers (-1.9 +/- .2 degrees C) compared with C (-1.2 +/- .2 degrees C) or T heifers (-.8 +/- .2 degrees C). No heifers exhibited estrus during the treatment period. During the posttreatment period, T heifers gained the most BW and BCS (93.9 +/- 6.1 kg; 1.14 +/- .13 units), C heifers were intermediate (67.0 +/- 6.1 kg; .86 +/-. 13 units), and PTU heifers gained the least (22.2 +/- 6.1 kg; -.14 +/- .13 units; P < .05). The reversal in BW and BCS gains during the posttreatment period corresponded to periods of transient hypo- and hyperthyroidism in T and PTU heifers, respectively. Age and BW at puberty and pregnancy were similar among all treatment groups. The BCS for T heifers was lower (5.7 +/- .2 units; P < .05) at puberty and pregnancy than for PTU heifers (6.6 +/- .2 units). Induction of hypothyroidism resulted in significant increases in BW and BCS during the treatment period, but these increases were not sufficient to dramatically affect reproductive performance of Brahman heifers.     

Bovine viral diarrhea virus (BVDV) infection in relation to fertility in heifers

In this study, blood serum and leukocyte samples were collected from 400 Holstein heifers, all of which appeared to be healthy. Antibodies (Ab) against bovine viral diarrhea virus (BVDV) were detected in 57 serum samples, and BVDV antigen (Ag) was detected in 38 leukocyte samples. There were statistically important differences between the average first insemination ages (FIT) of the BVDV (Ag-/Ab+) heifers (p<0.0001) (pregnant p<0.05, nonpregnant p<0.0001) and BVDV (Ag-/Ab-) heifers. The average conception rates (CR) of BVDV (Ag-/Ab+) heifers and BVDV (Ag-/Ab-) heifers were not significant statistically. There were statistically important differences in average FIT between persistent infected (PI) BVDV (Ag+/Ab-) heifers (p<0.0001; PI pregnant p<0.05, PI nonpregnant p<0.0001) and BVDV (Ag-/Ab-) heifers. No significant differences in average CR between PI BVDV (Ag+/Ab-) heifers and BVDV (Ag-/Ab-) heifers were found. The differences in average FIT between BVDV (Ag+/Ab+; p<0.0001; nonpregnant p<0.0001) and BVDV (Ag-/Ab-) heifers were important statistically. Although there were no BVDV (Ag+/Ab+) pregnant heifers, the differences in average CR between BVDV (Ag+/Ab+) pregnant heifers and BVDV (Ag-/Ab-) heifers were found to be statistically important (p<0.0001). We conclude that fertility is affected in heifers with BVDV (Ag-/Ab+, Ag+/Ab- and Ag+/Ab+).