Effect of urease injection on body weights of growing rats and chicks

Effects of direct-fed microorganisms and enzyme blend co-administration on intestinal bacteria in broilers fed diets with or without antibiotics

Direct-fed microorganisms (DFM) and exogenous enzymes have been demonstrated to improve growth performance in poultry and are potentially important alternatives to antibiotic growth promoters (AGP). We investigated the administration of a feed additive composed of a DFM product containing spores of 3 Bacillus amyloliquefaciens strains and an enzyme blend of endo-xylanase, α-amylase, and serine-protease in diets with or without sub-therapeutic antibiotics in broiler chickens over a 42-d growth period. Evaluation of growth performance determined feed efficiency of broiler chickens which were administered the feed additive was comparable to those fed a diet containing AGPs. Characterization of the gastrointestinal microbiota using culture-dependent methods determined administration of the feed additive increased counts of total Lactic Acid Bacteria (LAB) relative to a negative control and reduced Clostridium perfringens to levels similar to antibiotic administration. Additionally, greater counts of total LAB were observed to be significantly associated with reduced feed conversion ratio, whereas greater counts of C. perfringens were observed to be significantly associated with increased feed conversion ratio. Our results suggest the co-administration of DFMs and exogenous enzymes may be an important component of antibiotic free poultry production programs and LAB and C. perfringens may be important targets in the development of alternatives to AGPs in poultry production.

Ureases in the gastrointestinal tracts of ruminant and monogastric animals and their implication in urea-N/ammonia metabolism: A review

Urea in diets of ruminants has been investigated to substitute expensive animal and vegetable protein sources for more than a century, and has been widely incorporated in diets of ruminants for many years. Urea is also recycled to the fermentative parts of the gastrointestinal (GI) tracts through saliva or direct secretory flux from blood depending upon the dietary situations. Within the GI tracts, urea is hydrolyzed to ammonia by urease enzymes produced by GI microorganisms and subsequent ammonia utilization serves the synthesis of microbial protein. In ruminants, excessive urease activity in the rumen may lead to urea/ammonia toxicity when high amounts of urea are fed to animals; and in non-ruminants, ammonia concentrations in the GI content and milieu may cause damage to the GI mucosa, resulting in impaired nutrient absorption, futile energy and protein spillage and decreased growth performance. Relatively little attention has been directed to this area by researchers. Therefore, the present review intends to discuss current knowledge in ureolytic bacterial populations, urease activities and factors affecting them, urea metabolism by microorganisms, and the application of inhibitors of urease activity in livestock animals. The information related to the ureolytic bacteria and urease activity could be useful for improving protein utilization efficiency in ruminants and for the reduction of the ammonia concentration in GI tracts of monogastric animals. Application of recent molecular methods can be expected to provide rationales for improved strategies to modulate urease and urea dynamics in the GI tract. This would lead to improved GI health, production performance and environmental compatibility of livestock production.

Effects of two herbal extracts and virginiamycin supplementation on growth performance, intestinal microflora population and Fatty Acid composition in broiler chickens

The competency of garlic and pennywort to improve broiler chicken growth and influence intestinal microbial communities and fatty acid composition of breast meat were studied. Two hundred forty, "day-old" chicks were randomly allocated to 4 treatment groups consisting of 6 replications of 10 chicks in each pen. The groups were assigned to receive treatment diets as follows: i) basal diet (control), ii) basal diet plus 0.5% garlic powder (GP), iii) basal diet plus 0.5% pennywort powder (PW) and iv) 0.002% virginiamycin (VM). Birds were killed at day 42 and intestinal samples were collected to assess for Lactobacillus and Escherichia coli. The pectoralis profundus from chicken breast samples was obtained from 10 birds from each treatment group on day 42 and frozen at -20°C for further analyses. Fatty acid profile of breast muscles was determined using gas liquid chromatography. Feed intake and weight gain of broilers fed with GP, PW, and VM were significantly higher (p<0.05) compared to control. Feeding chicks GP, PW, and VM significantly reduced Escherichia coli count (p<0.05) while Lactobacillus spp count were significantly higher (p<0.05) in the gut when compared to control group on day 42. Supplemented diet containing pennywort increased the C18:3n-3 fatty acid composition of chickens' breast muscle. Garlic and pennywort may be useful in modulating broiler guts as they control the enteropathogens that help to utilize feed efficiently. This subsequently enhances the growth performances of broiler chickens.

Production of an egg yolk antibody specific to microbial uricase and its inhibitory effects on uricase activity

Ammonia gas produced from poultry manure can be a potential source of environmental pollution. Microbial uricase in poultry manure is an important target enzyme to reduce ammonia production because ammonia is mainly generated from the microbial decomposition of uric acid in the manure. Thus, the inhibition of microbial uricase is critical in preventing NH3 volatilization. A potential method of inhibiting uricase activity is the use of antibodies specific to microbial uricase. Therefore, this study was designed to evaluate 1) the production of the uricase-specific egg yolk antibody (IgY) from immunized hens and 2) the effect of the uricase-specific IgY on the activity of uricase. A total of 12 Single Comb White Leghorn hens were injected intramuscularly with uricase from Arthrobacter globiformis. The hens were immunized a second and third time at 1 and 2 wk, respectively, after the initial injection. The production of uricase-specific IgY was first detected at 2 wk after the initial immunization, and levels increased more than threefold at 4 wk. The method including water extraction, ammonium sulfate precipitation, and ethanol precipitation showed the most acceptable IgY purity and over 97% uricase-specific IgY recovery. Finally, the effect of the uricase-specific IgY on uricase activity was determined by a uricase assay. The slope ratio showed that the immune-IgY from the uricase-immunized hens and nonimmune IgY from nonimmunized control hens reduced uricase degradation by 58 and 43%, respectively, compared to the uricase treatment. The regression slope indicated that the immune IgY and nonimmune IgY treatments had a significant inhibitory effects on uricase activity compared to the uricase.

Alternatives to the use of antibiotics as growth promoters for monogastric animals

Recently, more and more is becoming known about the mode of action of antibiotics as growth promoters (AMGP), particularly in relation to the development of microbial resistance. Consequently, the use of these AMGP is already restricted or forbidden in many countries. Therefore, to compensate for the possible decrease in production, a lot of work is now being done to investigate possible alternatives. Suitable alternatives must be both proven and cost-effective, for the conditions and diets as used at the farm level.

Research note: increased growth of chicks and poults obtained from hens injected with jackbean urease

Two experiments were conducted using 120 Single Comb White Leghorn (SCWL) hens and 40 turkey hens. Hens were randomly assigned to two treatments: those injected with urease and controls injected only with adjuvant. At 22 wk of age, half of the SCWL hens were injected intramuscularly with 12 Sumner units of jackbean urease suspended in incomplete adjuvant six times in 26 wk. Turkey hens were injected twice at weekly intervals with 70 Sumner units. The other half of the breeders received adjuvant without urease (control). Urease injection into SCWL hens had no effect on feed consumption, feed conversion, and percentage fertility, hatchability, and hatch of all eggs set, but egg weight and body weight of chicks at hatch and at 3 wk of age were significantly higher as compared with the control hens. In the case of turkey hens, percentage hatchability and progeny body weight were significantly higher as a result of urease injection.

Improved growth in the progeny of hens immunized with jackbean urease

Three experiments were conducted with Single Comb White Leghorn and broiler breeder hens. Half of the experimental hens were injected with jackbean urease enzyme and the other half served as uninjected or adjuvant-injected controls. Chicks hatched from urease-injected or control hens were placed factorially (2 x 2) on diets with or without antibiotics. Urease injection of hens resulted in significant improvements in percent fertility and hatch compared with values for control hens. Depending on age, both urease injection and antibiotic feeding stimulated chick growth, independently of one another. Additive effects of these treatments resulted in significant improvements in body weight of chicks injected with urease and consuming antibiotics at all time periods compared with body weights of untreated controls.

Subtherapeutic levels of antibiotics in poultry feeds and their effects on weight gain, feed efficiency, and bacterial cholyltaurine hydrolase activity

A radiochemical method was developed to estimate cholyltaurine hydrolase potentials and rates of cholyltaurine hydrolysis in chicken intestinal homogenates. This method was used to monitor the effects of antibiotic feed additives on cholyltaurine hydrolase activity. Avoparcin, bacitracin methylenedisalisylic acid, efrotomycin, lincomycin, penicillin G procaine, and virginiamycin improved rate of weight gain and feed conversion of chicks and decreased cholyltaurine hydrolase activity in ileal homogenates relative to those of nonmedicated control birds. The results provided the first evidence that feeding selected antibiotics at subtherapeutic levels can affect bile acid-transforming enzymes in small-intestinal homogenates. The inverse relationship between growth performance and cholyltaurine hydrolase activity raises the possibility that specific inhibitors of this enzyme may promote weight gain and feed conversion in livestock and thereby reduce or eliminate the need for antibiotic feed additives.

Hydrolysis of urea in the gastrointestinal tract of "monoxenic" rats: effect of immunization with strains of ureolytic bacteria

Axenic rats, in whose feces urea is ordinarily excreted, were inoculated with ureolytic strains of Lactobacillus or Actinobacillus originally derived from the microflora of "holoxenic" rats. In these "monoxenic" animals, harboring one or another of the bacterial strains, fecal urea was hydrolyzed, with a more rapid onset of ureolysis in the case of Actinobacillus as compared with Lactobacillus. In vitro, a parallel difference between the two strains with regard to the onset of ureolysis was observed, hydrolysis beginning at the onset of growth in the case of Actinobacillus and only at the end of the exponential growth phase in the case of Lactobacillus. Extracellular urease activity was demonstrated in cultures of Lactobacillus, whereas none was found extracellularly with Actinobacillus. The pH optimum for the Lactobacillus urease in vitro was found to be 3.0, whereas the corresponding value for Actinobacillus was 6.0. In the two types of monoxenic rats, urea was consistently present in the small intestine and virtually absent from cecum and colon. Hydrolysis of urea in stomach was almost complete in rats bearing Lactobacillus but much less so in animals monoxenic with Actinobacillus, despite essentially equal numbers of organisms in that location. When rats carrying a monoflora of ureolytic Lactobacillus were immunized with either whole cells or soluble extract of the same organism, urea appeared in cecum and feces, indicating suppression of ureolytic activity. Immunization with an extract of nonureolytic Lactobacillus failed to produce such a result. Similar immunization techniques applied to animals monoassociated with ureolytic Actinobacillus did not alter ureolysis, and no appreciable quantity of urea appeared in feces. These studies demonstrate that it is indeed possible to inhibit the ureolytic activity of some bacteria in vivo by immunological means, but that the urease system of other organisms may not be as amenable to such manipulation.