Antidiuretic action of vasoactive endothelins in the in situ perfused rainbow trout kidney

The present studies examined, for the first time, the renal actions of endothelin-1 (ET-1) and Sarafotoxin S6b (SRTX-6b) (an endothelin-like peptide from snake venom) at 10^-11 M and 10^-9 M, using the in situ perfused kidney of the rainbow trout, Oncorhynchus mykiss. In further studies ET-1 (10^-9 M) was accompanied by Captopril (5 × 10^-4 M) to inhibit angiotensin II formation and determine whether the newly-identified intrarenal renin-angiotensin system (RAS) in the trout kidney was involved in ET-1's actions. These studies demonstrated that ET-1 and SRTX-S6b constrict the trout trunk vasculature, increasing vascular resistance and decreasing perfusate flow rates. Captopril did not affect this response and therefore angiotensin II is not implicated in the vascular responses. Direct action of endothelins on vascular receptors is indicated which, in vivo, is likely to be involved in regulation of renal vascular tone. Both ET-1 and SRTX-6b induced immediate decreases in glomerular filtration rates (GFR) reaching 30% and 34% decrease with 10^-11 M ET-1 and SRTX-6b respectively and 50% and 57% decrease with 10^-9 M ET-1 and SRTX-6b respectively. Urine flow rates decreased to a slightly lesser extent because of decreased tubular reabsorption of water; relative free water clearances increased from approximately 17% to 21% while urine/plasma inulin concentration ratios decreased slightly. This significant depressed urine osmolarity. Captopril completely blocked the effects of endothelins on tubular water reabsorption suggesting intrarenal RAS involvement in this action, although a kinin-mediated effect cannot, at this stage, be excluded. The glomerular antidiuretic action of ET-1 and SRTX-6b partially reflected a decreased population of filtering nephrons (41% filtering in control kidneys, 32–36% filtering in the presence of 10^-11 M M ET-1/SRTX-6b, 31–32% filtering in the presence of 10^-9 M ET-1/SRTX-6b). In addition, 25–40% reductions of single nephron filtration rates were estimated. Glomerular actions of endothelins were partially inhibited by Captopril, suggesting either that renal endothelins have both direct renal actions and secondary effects through activation of the renal RAS, or that kinins can modulate the renal actions of endothelins.     

Effect of chronic lead intoxication on the distribution and elimination of amoxicillin in goats

A study of amoxicillin pharmacokinetics was conducted in healthy goats and goats with chronic lead intoxication. The intoxicated goats had increased serum concentrations of liver enzymes (alanine aminotransferase and γ-glutamyl transferase), blood urea nitrogen, and reactivated δ-aminolevulinic acid dehydratase compared to the controls. Following intravenous amoxicillin (10 mg/kg bw) in control and lead-intoxicated goats, elimination half-lives were 4.14 and 1.26 h, respectively. The volumes of distribution based on the terminal phase were 1.19 and 0.38 L/kg, respectively, and those at steady-state were 0.54 and 0.18 L/kg, respectively. After intramuscular (IM) amoxicillin (10 mg/kg bw) in lead-intoxicated goats and control animals, the absorption, distribution, and elimination of the drug were more rapid in lead-intoxicated goats than the controls. Peak serum concentrations of 21.89 and 12.19 µg/mL were achieved at 1 h and 2 h, respectively, in lead-intoxicated and control goats. Amoxicillin bioavailability in the lead-intoxicated goats decreased 20% compared to the controls. After amoxicillin, more of the drug was excreted in the urine from lead-intoxicated goats than the controls. Our results suggested that lead intoxication in goats increases the rate of amoxicillin absorption after IM administration and distribution and elimination. Thus, lead intoxication may impair the therapeutic effectiveness of amoxicillin.     

Offspring from non-stimulated calves at an age younger than two months: a preliminary report

This study investigated the viability of embryos from non-stimulated 2-3-month-old calves generated in vitro using oocytes from follicles of defined size in terms of their ability to produce full-term pregnancies. Ablation of follicles>or=4 mm was used to induce the emergence of a new follicular wave, and calves (n=3) were laparoscopically punctured three times at 7-day-intervals to recover cumulus-oocyte-complexes (COCs) from follicles>8 (group A) and between 4-8 mm (group B). Calves were aged 49, 56, and 80 days, respectively, at first recovery. Morphologically intact COCs were subjected to in vitro maturation, fertilization, and embryo culture, and compact morulae/blastocysts were transferred on day 7 post-insemination to synchronized virgin heifers. Blood typing was used for maternity analysis. A total of 29 COCs were recovered, 21 cultured, yielding 11 cleaved embryos (52.4%) and 6 compact morulae/blastocysts (28.6%). No differences were observed between groups. Transfer of the 6 embryos to 5 recipients resulted in three pregnancies (one from group A and two from group B). Two normal male offspring (both from group B), with birth weights of 44 and 51 kg, were born, and two donor calves, aged 56 and 59 days, were identified as the dams. In conclusion, the results demonstrate that embryos generated in vitro from oocytes from non-stimulated calves at an age younger than two months are viable in terms of their ability to produce full-term pregnancies, and suggest that the viability of calf embryos is not related to follicle size.     

Biochemical effect of steroid anaesthesia on some liver function tests in goat

Saffan, as a type of steroid anaesthetic, was tested to demonstrate the effect of its administration on liver function in goat. For this purpose, 40 healthy animals were divided into 4 equal groups. The 1st 2 groups were given 2 or 4 mg saffan/kg body weight (B.W.), respectively. A mixture of saffan (1 mg) and xylazine (0.1 mg)/kg B.W. was given to the 3rd group. Xylazine alone was offered to the 4th group in a concentration of 0.1 mg/kg B.W. Serum samples from all groups were analysed to measure the quantities of glucose, total protein, total and direct bilirubin as well as the activity levels of transaminases. Increased glucose levels resulted from administration of saffan which evoked more hyperglycaemia than its mixture with xylazine or xylazine alone. The hyperglycaemic effect of both doses of saffan was equivocal beyond 2 hours. The effect then differed, and glucose elevation reached the 4 fold level by 2 mg saffan and the 3 fold level by 4 mg. Total serum protein, direct and total bilirubin as well as GPT and GOT were not changed in the 4 experimental groups. This was a good indication to normal liver function in the course of administration of steroid anaesthetics to goat.     

Study into wild Egyptian plants of potential medicinal activity. Ninth communication: hypoglycaemic activity of some selected plants in normal fasting and alloxanised rats

31 desert plants belonging to 17 families were collected from different Egyptian localities. 21 plants extracts were orally given to normal rats, and 15 were tested on fasted and to alloxanised rats. The results were compared with a standard oral hypoglycaemic drug (Daonil, Hoechst) used as a positive control. The following findings were obtained: 8 plants exhibited persistent hypoglycaemic effects, Lycium shawii, Salvia (S.) aegyptiaca, Pergularia tomentosa, Convolvulus (C.) althaeoides, Haloxylon salicornicum, Ephedra alata, Scrophularia deserti, and Crotalaria aegyptiaca. Transient hypoglycaemic effects appeared only 1 hour after administration in response to 4 plants, Silena succulenta, Lygos raetam, C. lanatus, and Pulicaria incisa. In the cases of Ochradenus baccatus and Zygophyllum album, slow hypoglycaemic activity was produced and appeared 3 hours after administration. 5 plants showed hypoglycaemic effects viz, Thymus capitatus, Launaea nudicaulis, Conyza dioscorides, Nitraria retusa, and Limonium tubiflorum. Among the 15 plant extracts tested on alloxanised diabetic rats only 4 showed hypoglycaemic effects more potent than those of the administered dose of Daonil. These were Matthiola livida, S. aegyptiaca, Astragalus species, and Arthrocnemum glaucum. The hypoglycaemic effect of S. aegyptiaca in fasting rats has been confirmed also in alloxanised diabetic animals. This emphasises the importance of conducting both experiments in order to obtain a reliable conclusion.     

Pharmacokinetics and pharmacodynamics of intramammary cefquinome in lactating goats with and without experimentally induced Staphylococcus aureus mastitis

Values for pharmacokinetic variables are usually obtained in healthy animals, whereas drugs are frequently administered to diseased animals. This study investigated cefquinome pharmacokinetics in healthy goats and goats with experimentally induced mastitis. Five adult lactating goats received 75 mg of cefquinome intramammary infusion using a commercially available product into one udder half in healthy goats and goats with clinical mastitis that was induced by intracisternal infusion of 100 cfu of Staphylococcus aureus ATCC 29213 suspended in 5 ml of sterile culture broth. Cefquinome concentrations were determined in plasma and skimmed milk samples using high‐performance liquid chromatography (HPLC). Pharmacodynamics was investigated using the California Mastitis Test and pH of milk. Experimentally induced mastitis significantly increased the California Mastitis Test score and pH, and decreased the maximal cefquinome concentration and shortened the half‐life in milk when compared to healthy goats. In conclusion, mastitis facilitated the absorption of cefquinome from the mammary gland of lactating goats and induced marked changes in milk pH, emphasizing the importance of performing pharmacokinetic studies of antimicrobial agents in infected animals.     

Effect of dietary supplementation of organic zinc on laying performance,egg quality and some biochemical parameters of laying hens

This study was conducted to evaluate the effects of zinc methionine (Zn‐Met) supplementation on the performance, egg quality, antioxidant status and some biochemical parameters of blood serum in laying hens from 22 to 34 weeks of age. A total of 120 Hisex Brown laying hens of 22‐week‐old were randomly allocated into five treatments with six cage replicates for each (four hens/replicate). Dietary treatments consisted of the basal diet with no Zn‐Met supplementation (control group) and basal diet supplemented with 25, 50, 75 or 100 mg Zn‐Met/kg diet. No significant differences were observed on body weight, body weight gain or feed conversion ratio due to dietary Zn‐Met supplementation. However, highly significant impact was observed on daily feed intake. Egg number, egg weight and egg mass were increased in the group fed diet supplemented with the highest level of Zn‐Met (100 mg/kg of diet) as compared to other groups. All egg quality traits were statistically (p > .05 or .01) affected as a response to dietary Zn‐Met supplementation except egg shape index, shell percentage and yolk index. In comparison with the control group, dietary supplementation of 25, 50, 75 or 100 mg Zn‐Met/kg decreased serum triglyceride and LDL‐cholesterol levels. Serum cholesterol level was increased with all dietary levels of Zn‐Met in comparison with the control group. Dietary Zn‐Met supplementation increased the serum content of zinc, where the highest values were recorded with 50 and 100 mg Zn‐Met/kg diet. Dietary Zn‐Met levels did not affect the antioxidant indices in blood serum except for the activity of copper–zinc superoxide dismutase (Cu‐Zn‐SOD). The activity of Cu‐Zn‐SOD was increased with Zn‐Met supplementations with no differences among supplemental zinc levels. It is concluded that dietary Zn‐Met supplementation reduced serum triglyceride, LDL‐cholesterol and increased Zn status and resulted in promoting antioxidant ability of laying hens, and the addition of 100 mg Zn‐Met/kg to layer diet was appropriate for improving the above parameters in addition to egg production indices and Haugh unit score.     

An evaluation of alternative selection indexes for a non‐linear profit trait approaching its economic optimum

This study used simulation to evaluate the performance of alternative selection index configurations in the context of a breeding programme where a trait with a non‐linear economic value is approaching an economic optimum. The simulation used a simple population structure that approximately mimics selection in dual purpose sheep flocks in New Zealand (NZ). In the NZ dual purpose sheep population, number of lambs born is a genetic trait that is approaching an economic optimum, while genetically correlated growth traits have linear economic values and are not approaching any optimum. The predominant view among theoretical livestock geneticists is that the optimal approach to select for nonlinear profit traits is to use a linear selection index and to update it regularly. However, there are some nonlinear index approaches that have not been evaluated. This study assessed the efficiency of the following four alternative selection index approaches in terms of genetic progress relative to each other: (i) a linear index, (ii) a linear index updated regularly, (iii) a nonlinear (quadratic) index, and (iv) a NLF index (nonlinear index below the optimum and then flat). The NLF approach does not reward or penalize animals for additional genetic merit beyond the trait optimum. It was found to be at least comparable in efficiency to the approach of regularly updating the linear index with short (15 year) and long (30 year) time frames. The relative efficiency of this approach was slightly reduced when the current average value of the nonlinear trait was close to the optimum. Finally, practical issues of industry application of indexes are considered and some potential practical benefits of efficient deployment of a NLF index in highly heterogeneous industries (breeds, flocks and production environments) such as in the NZ dual purpose sheep population are discussed.     

Effect of NPK and biofertilizer on date palm trees grown in Siwa Oasis,Egypt

The effect of applying chemical fertilizers alone or in combination with biofertilizer on the growth, yield and fruit quality and leaf mineral nutrient content of Sewy date palm was investigated in three successive seasons from 2004 to 2006. This study was carried out at the Siwa Oasis in the western desert of Egypt between longitude 25°18′ and 26°06′ E and latitudes 29°05′ and 29°20′ N. Chemical fertilizer applications were 1.2 or 1.5 kg N/tree, 0.065 or 0.044 kg P/tree and 0.250 or 0.420 kg K/tree. Nitrogen and potassium were given as three split applications, whereas P was mixed with organic manure (40 kg/palm tree) and supplied as a single application. Biofertilizer treatments were applied at both rates of N, P and K. The control treatment was the existing nutrient application of just 40 kg of organic sheep manure/tree/year, given as a single application. The results indicated that the application of the larger amounts of N, P and K increased the number of leaves and bunches per palm, fruit yield and total sugar content with a high level of fruit quality and production economics. In addition, this treatment increased the mineral content of leaves and reduced the biennial bearing phenomenon of Sewy date palm.