Effects of dietary corticosterone on peripheral blood lymphocyte and granulocyte populations in immature domestic fowl

Four-week-old chickens were fed on diets containing 0, 5, 10, 20 and 40 mg corticosterone per kg for eight days. Packed cell volume (PCV), the numbers of granulocytes (G) and lymphocytes (L), the G:L ratio and plasma corticosterone concentration were measured. Plasma corticosterone concentration was increased by dietary corticosterone from day 2 onwards. The number of lymphocytes was increased by serial bleeding but dietary corticosterone depressed the response and caused a dose-related lymphocytopenia from day 1. There was a dose related increase in granulocytes from day 4 and a dose-related increase in G:L ratio from day 1. A dose-related increase in PCV was evident only on days 2 and 4. Correlation coefficients showed little evidence of relationships between plasma corticosterone concentrations and the recorded blood variables.     

In vitro studies on the synthesis of intramuscular fat in the longissimus dorsh muscle of pigs

The amount of intramuscular fat is one factor contributing to the palatability of meat. As a preliminary attempt to study the capability of M. Longissimus dorxi in pigs to synthesize intramuscular lipids, an in vitro techniques was designed. Tissue alices were incubated with glucose U-C¹⁴ or acetate-1-C¹⁴ in the presence and absence of non-radioactive glucose and insulin. Following incubation, the quantities of C¹⁴-labelled total lipids, fatty acids, and individual lipid classes, produced from each substrate were determined. The results indicate that intramuscular lipids can be synthesized in the muscle tissue, but at a slow rate. It was found that the conversion of glucose into lipids, fatty acids, and triglycerides was markedly stimulated by an increase of the glucose concentration of the medium from 2 to 5 mM. Insulin had no effect on the amount of glucose converted into total lipids. However, at both glucose concentrations insulin significantly stimulated the utilization of glucose for production of giyearide-glycerol at the expense of fatty acid synthesis. Acetate was utilized to a greater extent than glucose for synthesis of fatty acids. The presence of glucose and insulin had no effect on the utilization of acetate for production of total lipids, fatty acids, and individual lipid classes. The major part of the radioactivity of total lipids was incorporated into the triglycerides both when glucose-U-C¹⁴ and acetate-1-C¹⁴ were used as substrates.     

Improved mouse blood smears using the DiffSpin slide spinner

Push smears of mouse blood prepared for differential white blood cell (WBC) determination often have many lysed WBCs, numerous RBC "ghosts", and poor morphology of intact RBCs. The purpose of this study was to compare the quality of peripheral blood smears prepared by 3 different methods and to optimize a technique for mouse blood differential WBC determination. Peripheral blood smears were prepared from blood obtained from clinically normal adult mice and human adults. Differential WBC counts, numbers of lysed WBCs/100 intact WBCs, and RBC morphology were compared in blood smears made using the standard push method with undiluted blood, the push method with blood diluted 1:5 with bovine serum albumin, and in centrifugally-prepared smears made with the DiffSpin Slide Spinner (StatSpin, Norwood, Mass, USA). The number of damaged WBCs in mouse versus human samples using the push method was compared using an unpaired Student's t test. ANOVA was used to compare differences in WBC differential counts and numbers of damaged WBCs among the 3 methods for each species. In addition, unpaired Student's t tests were used to compare each method against the other methods, within species. The number of damaged WBCs/100 intact WBCs was approximately 3 times higher in mouse than in human push smears (P=0.002). There was no significant difference in WBC differential cell counts among the 3 methods in either species. However, compared with both push techniques, a significantly (P <.01) greater number of intact cells was observed with the DiffSpin technique for mouse blood samples (damaged WBC/100 intact cells = 4.4 +/- 2.6 for DiffSpin smears, 9.5 +/- 3.9 for push smears with added albumin, and 31.3 +/- 10.2 for standard push smears). DiffSpin mouse blood smears consistently had better RBC morphology when compared with standard push smears. In conclusion, the DiffSpin Slide Spinner produced optimal smears of mouse blood for WBC differential determination and analysis of RBC morphology.     

A serological survey for antibodies against foot-and-mouth disease virus (FMDV) in domestic pigs during outbreaks in Kenya

Foot-and-mouth disease (FMD) is endemic in Kenya and has been well studied in cattle, but not in pigs, yet the role of pigs is recognised in FMD-free areas. This study investigated the presence of antibodies against FMD virus (FMDV) in pigs sampled during a countrywide random survey for FMD in cattle coinciding with SAT 1 FMDV outbreaks in cattle. A total of 191 serum samples were collected from clinically healthy pigs in 17 districts. Forty-two of the 191 sera were from pigs vaccinated against serotypes O/A/SAT 2 FMDV. Antibodies against FMDV non-structural proteins were found in sera from 30 vaccinated and 71 non-vaccinated pigs, altogether 101/191 sera (53 %), and 91 % of these (92/101) also had antibodies measurable by serotype-specific ELISAs, predominantly directed against SAT 1 with titres of 10–320. However, only five high titres against SAT 1 in vaccinated pigs were confirmed by virus neutralisation test (VNT). Due to high degree of agreement between the two ELISAs, it was concluded that positive pigs had been infected with FMDV. Implications of these results for the role of pigs in the epidemiology of FMD in Kenya are discussed, and in-depth studies are recommended.     

Response of wheat tillers at different growing stages to gametocide treatment

Summary The effects of the gametocides Ethrel, RH-532, and RH-2956 on wheat tillers at various stages of development were studied. The gametocides were applied to Anza and Yecora 70, two spring wheat (Triticum aestivum L.) varieties, at three rates of foliar application when the main tillers were at meiosis. Ethrel was less effective in causing sterility than RH-532 and RH-2956. Anza showed greater induced sterility than Yecora 70 when treated with these gametocides. Ethrel affected only late tillers treated at or before meiosis. RH-532 and RH-2956 at the high application rate were equally effective for Anza. RH-2956 at the high application rate induced uniform and maximum sterility in early and late tillers of both Anza and Yecora 70.     

The Influence of Different Protein,Fat and Mineral Levels on the Digestibility of Fat and Fatty Acids Measured at the Terminal Ileum and in Faeces of Growing Pigs

Abstract

The influence of dietary protein, fat and mineral levels on crude fat and fatty acid digestibility was investigated in growing pigs. The experiment was a factorial design with two levels of protein (normal and high), two levels of dietary fat (3 and 15% of DM) and three levels of minerals (50, 100 and 150% of Danish Standard). Four litters, each of six female pigs, were used in the experiment.

Increasing the dietary protein content resulted in a moderate but significant increase in the ileal digestibility of fatty acids. The increase was most pronounced for the saturated fatty acids. Addition of animal fat to the basal diet caused a substantial increase in ileal digestibility of all fatty acids except stearic acid (18:0). A variation in the dietary mineral content of ±50% of the Danish Standard had no significant influence on ileal digestibility of crude fat and fatty acids. Apparently, microbial hydrogenation occurred in the hind-gut, but the increase in stearic acid (18:0) excretion could not be explained solely by biohydrogenation of unsaturated fatty acids. The interactions between dietary protein and fat on the increase of faecal 18:0 showed that the dietary composition had a very complex effect on the microbial activity in the hind-gut. Consequently, determination of fatty acid digestibility should be performed at the terminal ileum, whereas crude fat (Stoldt) digestibility can be carried out on faecal material.     

Comparison of the hydrolysis of bovine κ-casein by camel and bovine chymosin: a kinetic and specificity study

Bovine chymosin constitutes a traditional ingredient for enzymatic milk coagulation in cheese making, providing a strong clotting capacity and low general proteolytic activity. Recently, these properties were surpassed by camel chymosin, but the mechanistic difference behind their action is not yet clear. We used capillary electrophoresis and reversed-phase liquid chromatography-mass spectrometry to compare the first site of hydrolysis of camel and bovine chymosin on bovine κ-casein (CN) and to determine the kinetic parameters of this reaction (pH 6.5; 32 °C). The enzymes showed identical specificities, cleaving the Phe105-Met106 bond of κ-CN to produce para-κ-CN and caseinomacropeptide. Initial formation rates of both products validated Michaelis-Menten modeling of the kinetic properties of both enzymes. Camel chymosin bound κ-CN with ～30% lower affinity (K(M)) and exhibited a 60% higher turnover rate (k(cat)), resulting in ～15% higher catalytic efficiency (k(cat)/K(M)) as compared to bovine chymosin. A local, less dense negatively charged cluster on the surface of camel chymosin may weaken electrostatic binding to the His-Pro cluster of κ-CN to simultaneously impart reduced substrate affinity and accelerated enzyme-substrate dissociation as compared to bovine chymosin.     

Comment on "Saturation of the southern ocean CO2 sink due to recent climate change"

Unlike Le Quéré et al. (Reports, 22 June 2007, p. 1735), we do not find a saturating Southern Ocean carbon sink due to recent climate change. In our ocean model, observed wind forcing causes reduced carbon uptake, but heat and freshwater flux forcing cause increased uptake. Our inversions of atmospheric carbon dioxide show that the Southern Ocean sink trend is dependent on network choice.