Cathelicidins comprise a family of antimicrobial peptides sharing a highly conserved cathelin domain. Here we report that the entire chicken genome encodes three cathelicidins, namely fowlicidin-1 to -3, which are densely clustered within a 7.5-kb distance at the proximal end of chromosome 2p. Each fowlicidin gene adopts a fourexon, three-intron structure, typical for a mammalian cathelicidin. Phylogenetic analysis revealed that fowlicidins and a group of distantly related mammalian cathelicidins known as neutrophilic granule proteins are likely to originate from a common ancestral gene prior to the separation of birds from mammals, whereas other classic mammalian cathelicidins may have been duplicated from the primordial gene for neutrophilic granule proteins after mammals and birds are diverged. Similar to ovine cathelicidin SMAP-29, putatively mature fowlicidins displayed potent and salt-independent activities against a range of Gram-negative and Gram- Cationic antimicrobial peptides comprise a large group of gene-encoded molecules that have been discovered in virtually all species of life, playing a critical role in innate host defense and disease resistance (1-4). Two major families of antimicrobial peptides exist in mammals, namely defensins and cathelicidins. Whereas defensins are characterized by the presence of six cysteines at well defined positions (5, 6), all cathelicidins share a highly conserved "cathelin" pro-sequence at the N terminus, followed by diversified, cationic mature sequences at the C terminus (7-9). Cathelicidins are most abundantly present in the granules of phagocytic cells and also to a lesser extent in many other cell types such as mucosal epithelial cells and skin keratinocytes (7-9).Upon activation, most cathelicidin precursors are proteolytically cleaved to release the cathelin domain and the C-terminal mature peptides with antimicrobial activities, although the unprocessed or differentially processed forms are often found in the biological fluids where cathelicidins are expressed (8, 9). The physiological role of the cathelin domain or uncleaved precursors remains elusive but is more likely to be involved in immune modulation other than just bacterial killing (10, 11).In addition to their ability to directly kill a wide range of bacteria, fungi, and enveloped viruses, mature cathelicidins are actively involved in various phases of host defense. Certain cathelicidins are found to chemoattract and activate a variety of immune cells, inhibit NADPH oxidase, kill activated lymphocytes, and promote angiogenesis and wound healing (1,8,9). Consistent with their critical role in host defense and disease resistance, aberrant expression of cathelicidins is often associated with various disease processes. For example, LL-37/hCAP-18 deficiency correlates with recurrent skin infections in the atopic dermatitis patients (12) and chronic periodontal disease in morbus Kostmann patients (13). Similarly, deletion of the cathelicidin gene (CRAMP) in mice resulted in a loss of protection against sk...

Cultures of lactobacilli identified as Lactobacillus acidophilus from the intestinal contents of young calves varied in their ability to grow in broth containing .3% oxgall compared with control broth. Frozen concentrated cultures were prepared from a strain exhibiting low tolerance to bile and from a strain exhibiting high tolerance to bile. Plate counts were comparable from the concentrated cultures before and after frozen storage on lactobacilli MRS agar with and without .15% oxgall. In a feeding trial involving newborn dairy calves supplementation of the diet with the more bile resistant strain of Lactobacillus acidophilus caused greater increases of numbers of facultative lactobabilli in the upper small intestines than did the strain exhibiting lower resistance to bile. It was not possible to determine whether the lactobacilli would prevent intestinal infections in the calves challenged with enteropathogenic Escherichia coli. This portion of the study failed as the challenge with Escherichia coli did not cause infections even in control animals.

In 1989, Fuller defined a probiotic as 'a live microbial feed supplement which beneficially affects the host animal by improving its intestinal microbial balance', thereby emphasising the importance of live cells. In the strictest sense of this definition, it may be premature to describe fungal additives given to ruminants as probiotics, as although they are active in the rumen, post-ruminal effects cannot be ruled out, and the requirement for live cells has not been totally established.The rumen environment can be altered by using chemicals, or with the use of antibiotic/microbial fermentation products; however, the fact that fungal cultures containing either live or dead cells may play a significant role in controlling rumen fermentation is new. Two fungal cultures have received considerable attention.Saccharomyces cerroisiae ( 5 x 10' live organisms g -' plus growth medium) (yeast culture) (SC) and Aspergillus oryzur (a fungal additive) (OA) have been shown to increase productivity of ruminants (c. 5-7% increase in fat-corrected milk yield in lactating dairy cows) when added in small quantities to the diet. At present, the work carried out with SC has involved the use of yeast strain 1026; results in the literature indicate that the strain of organism is important. The increase in production results from an increase in feed intake, and at present there has been no need to postulate a more fundamental metabolic response. Increased feed intake has been related to increases in the rate of degradation of fibrous materials in the rumen and to effects on rumen fermentation patterns.Evidence suggests that to be effective in the rumen the fungal microorganisms do not need t o reproduce; however, this does not rule out the fact that the cells need t o be metabolically active. The cells retain viability in the rumen, and increased numbers of viable yeast cells are found at the proximal duodenum and terminal ileum. Measurements of the effects of the addition of fungal cultures to the diet on the degradability of hay or straw incubated in nylon bags has shown that the initial rate of degradation is increased by approximately 20% but there is no effect on the potential degradability. These results have been confirmed by measurement of cellulose digestion in pure or co-culture of SC with Bacteroides succinoyenes. This indicates that the activity of fungal cultures is directed more

There are several potential health or nutritional benefits possible from some species of lactic acid bacteria. Among these are: improved nutritional value of food, control of intestinal infections, improved digestion of lactose, control of some types of cancer, and control of serum cholesterol levels. Some potential benefits may result from growth and action of the bacteria during the manufacture of cultured foods. Some may result from growth and action of certain species of the lactic acid bacteria in the intestinal tract following ingestion of foods containing them. In selecting a culture to produce a specific benefit it is necessary to consider not only the wide variation among species of the lactic acid bacteria but also that among strains within a given species. With the possible exception of improving lactose utilization by persons who are lactose maldigestors, no specific health or nutritional claims can yet be made for the lactic acid bacteria.

Since every 1% reduction in serum cholesterol concentration is associated with an estimated 2% to 3% reduction in risk for coronary heart disease, regular intake of FM containing an appropriate strain of L. acidophilus has the potential of reducing risk for coronary heart disease by 6 to 10%.