Aims: To determine susceptibility of Clostridium perfringens strains CCM 4435 T and CNCTC 5459 to C 2 -C 18 fatty acids, and evaluate influence of pH in cultures grown on glucose. Straw particles were added to cultures to simulate the presence of solid phase of the digestive tract milieu. Methods and Results: Antimicrobial activity of fatty acids was expressed as a concentration at which only 50% of the initial glucose was utilized. Lauric acid showed the highest antimicrobial activity, followed by myristic, capric, oleic and caprylic acid. Only strain CNCTC 5459 was susceptible to linoleic acid. Neither caproic acid and acids with a shorter carbon chain nor palmitic and stearic acid influenced substrate utilization. The antimicrobial activity of myristic, oleic and linoleic acid decreased when clostridia were grown in the presence of straw particles. In cultures of both strains treated with capric and lauric acid at pH 5AE0-5AE3, the number of viable cells was <10 2 ml )1 . Only lauric acid reduced number of viable cells of both strains below 10 2 ml )1 at pH > 6. Transmission electron microscopy revealed separation of inner and outer membranes and cytoplasma disorganization in cells treated with lauric acid. Conclusions: Lauric acid had the highest activity towards C. perfringens among fatty acid tested. Its activity was not influenced by the presence of solid particles and did not cease at pH > 6. Significance and Impact of the Study: Lauric acid might be a means for control of clostridial infections in farm animals.

ISA Brown laying hens at 24 weeks of age, housed in laying battery cages, were used in this 4-group experiment. One group was fed a basal diet containing primarily maize, soybean meal and wheat. Selenium (Se) content of the basal diet was 0.07 mg/kg dry matter. The other hens received diets supplemented with Na 2 SeO 3 , Se-enriched yeast and Se-enriched alga Chlorella, respectively, in a concentration of 0.3 mg Se/kg. The experiment lasted twenty-seven weeks. Egg production, feed consumption, egg weight, physical parameters of egg white, yolk and egg shell were examined every third week and egg white and yolk Se content repeatedly. Se was determined by inductively coupled plasma mass spectrometry. All three sources of added Se increased the egg white and egg yolk Se content (P < 0.001). Selenium in the organic form increased further Se in the egg components compared to sodium selenite (P < 0.001). More Se was deposited in egg white than in egg yolk, especially in relation to the increasing time of the experiment. The increase of Se concentration in egg white corresponded with increasing egg white weight in both organic selenium sources (P < 0.05). Higher egg white thickness and better Haugh units were observed only in the Se-Chlorella group. Hens receiving the diet with Se-Chlorella also had better egg production compared to the basal diet (P < 0.05). Egg weight was significantly higher in the Se-Chlorella and Se-yeast groups compared to the basal diet and the diet with sodium selenite (P < 0.05). The Se-enriched alga Chlorella showed summarily best results.

This study examined the effects of supplementation of dietary sodium selenite and sodium enriched alga Chlorella on growth performance, selenium concentration in breast meat and excreta, activity of glutathione peroxidase in meat, and oxidative stability of meat in broilers. Sexed broiler cockerels Ross 308 were allotted to 3 dietary treatments, each comprising 100 chickens. The basal diet was supplemented with 0 (control) or 0.3 mg/kg Se from sodium selenite (SS) or Se-Chlorella (SCH). Dietary supplementation with SCH increased (P < 0.05) body weight. The breast muscle Se concentration was increased (P < 0.05) by SCH (0.70 mg/kg DM; 0.36 mg/kg DM in control) supplementation, but not (P > 0.05) by SS (0.49 mg/kg DM) supplementation. The concentration of Se in excreta was highest in the SS group. The activity of GSH-Px in breast meat was significant P < 0.05) in all treatments (0.16 U/g in control, 0.30 U/g in SS and 0.23 U/g in SCH group). The inclusion of SCH in the diet enhanced the oxidative stability of meat expressed as reduced malondialdehyde (MDA) values in breast meat after 0; 3 and 5 days storage in refrigerator at 3 to 5°C.

ABSTRACT:The effect of dietary supplementation of selenium in an organic form on performance, carcass traits and selenium content in tissues of broiler cockerels Ross 308 was studied. The soya-wheat-maize diet contained 50 mg vitamin E/kg. The experiment was conducted on 810 straight-run broiler cockerels randomly divided into 3 groups: group I -control, without selenium supplement; experimental group: II -0.3 mg Se/kg, Se-enriched yeast was applied as a Se source; III -0.3 mg Se/kg, Se-enriched alga Chlorella as a Se source. The broiler chickens were slaughtered at 42 days of age. In performance traits higher (P ≤ 0.05) live weight of broiler chickens was recorded in the experimental groups (II -2 430.6 g and III -2 425.2 g). There were no significant differences between the groups in feed conversion and mortality. Se-enriched alga had the best feed conversion, and selenium supplementation slightly increased mortality in both experimental groups. No significant differences between the groups were found out in carcass traits and dressing percentage. The content of selenium in breast and thigh muscle, feathers and excrements increased (P ≤ 0.05) in both experimental groups compared to the control group. Higher values in breast and thigh muscle and in feathers were measured in the group supplemented with selenium from Se-enriched yeast, also in comparison with the group supplemented with selenium from Se-enriched alga Chlorella. The broiler chickens receiving Chlorella had a higher (P ≤ 0.05) selenium content in excrements compared to the group with Se-enriched yeast. The selenium concentration in liver was higher (P ≤ 0.05) in both experimental groups compared to the control. The supplement of selenium from Se-yeast and Chlorella in the diet for broiler chickens increased the microelement concentration in muscle.

An experiment was conducted to compare the effect of dietary sodium selenite and selenomethionine on selenium and α-tocopherol concentration in breast meat, oxidative stability of meat in broilers, and on growth performance, but only as an unimportant criterion in this case. Sexed broiler cockerels Ross 308 were allocated to 3 dietary treatments, each comprising 100 chickens. The basal diet was supplemented with 0 (control) or 0.3 mg/kg Se from sodium selenite (SS) or selenomethionine (SM). Dietary supplementation with SM increased (P < 0.05) body weight, but only by about 3%. Breast muscle Se concentration was increased (P < 0.05) by both Se sources, but more by SM (1.32 mg/kg dry matter; 0.47 mg/kg DM in control). The concentration of Se in excreta was 3 times higher with SS supplement than with SM supplement. Dietary Se supplementation increased (P < 0.05) the α-tocopherol content of breast meat from 25.9 mg/kg DM in the control to 33.2 mg/kg DM when SM supplementation was used. Furthermore, lipid peroxidation decreased compared to the control. The inclusion of SM in the diet reduced (P < 0.05) malondialdehyde (MDA) values in breast samples after 0, 3, and 5 days of cooler storage, whereas SS decreased (P < 0.05) the MDA of breast meat after 0 and 3 days of storage. The results of this experiment indicate that selenomethionine in the diet of broilers is capable of simultaneously increasing the content of selenium and vitamin E in broiler meat plus its stability in storage.