Microbiological and chemical properties of litter from different chicken types and production systems.

Chicken litter is produced in large quantities from all types of poultry raising activities. It is primarily used for land application, thus it is essential to analyze its properties before it is released to the environment. The objective of this study is to compare the microbiological and chemical properties of litter generated from layer and broiler chickens reared under intensive and free-range production systems. The microbiological analysis consisted of the enumeration of total bacteria, total coliforms, Staphylococcus species, Salmonella species and Clostridium perfringens. Chicken litter from layers reared under intensive and free range systems showed lower mean total bacterial count than the litter collected from chicken broilers reared under either of the two systems (P=0.0291). The litter from intensive layers had the lowest mean total coliform counts (P=0.0222) while the lowest Staphylococcus species count was observed in the litter from free-range layers (P=0.0077). The C. perfringens count was the lowest in chicken litter from intensively raised broilers and layers (P=0.0001). The chemical properties of litter from the different chicken types and production systems were compared based on determination of pH, electrical conductivity, carbon, nitrogen, phosphorus, potassium, cadmium and zinc. Litter from free-range broilers showed the highest pH value (P=0.0005); however, the electrical conductivity was higher in the litter from both intensive and free-range layers compared to the litter from both broiler production systems (P=0.0117). Chicken litter from intensive systems had higher nitrogen content than litter from free-range systems (P=0.0000). The total phosphorus was the lowest in free-range broiler litter (P=0.0001), while the total potassium was the lowest in litter from intensively managed broilers (P=0.0000). Zinc appeared higher in litter from layers compared to that from broilers (P=0.0101). The cadmium content was higher in the litter from free-range broilers and layers compared to that in the litter from intensively managed systems (P=0.0439). Staphylococcus species in the litter as well as cadmium concentrations seem to be the most critical parameters presenting risks on the environment and on human health. Based on the lowest coliform counts (an indication of water pollution), the high nutrient levels and the low cadmium values, litter from intensively managed layers appears as the most suitable for application on agricultural soils.

Comparative impact of live chicken infectious anaemia virus vaccine versus natural exposure in meat chicken breeders on immunity to infectivity by CIA and inclusion body hepatitis viruses in their offspring.

The immunology and histopathology and the distribution of viral antigen in infections with chicken infectious anaemia virus (CIAV) and inclusion body hepatitis virus (IBHV) were compared in the broiler offspring of CIAV-vaccinated meat chicken breeders versus those in the offspring of breeders naturally exposed to field CIAV. No significant difference in the humoral antibody level specific for CIAV was observed between 5 and 33 weeks of age in the two breeder groups (p > 0.05). The maternal humoral immunity to CIAV in the day-old offspring of the groups did not differ significantly (p > 0.05). The humoral immunity to CIAV at 40 days of age indicated an absence of clinical signs of CIAV in the broiler offspring of both groups of breeders and this was associated with mean serum thymulin levels in offspring of both groups not differing significantly at 1 or 40 days of age. Histopathological and immunofluorescence observations did not differ significantly in the offspring of either group by CIAV or IBHV.

Immunopotentiation of a developed Salmonella enterica serotype enteritidis vaccine by thymulin and zinc in meat chicken breeders.

The humoral immunity, spleen and thymus weight indices, lymphocyte count in the thymus cortex, and granuloma diameter at vaccination sites were assessed in four differently immunopotentiated groups of meat chicken breeders. Breeders in the first two groups were given a killed Salmonella enterica serotype Enteritidis (SE) vaccine subcutaneously at 15 and 19 weeks of age. Breeders in the third and fourth groups were left unvaccinated. Breeders in the first group were further immunopotentiated with zinc and thymulin. Each bird in the first group was given the immunopotentiators intraperitoneally in a volume of 0.1 ml at intervals of 3 days for a period of 3 weeks, starting at 15 weeks of age. At each time, each bird in the first group received thymulin (10 ng) and ZnCl2 (1 micromol/L), using a carboxymethyl cellulose carrier, totalling 90 ng thymulin and 9 micromol of ZnCl2 per bird. Each bird in the first three groups was challenged orally with 6.7 x 10(6) cfu/ml of highly virulent SE organisms, at an age of 22 weeks. The first group, which had received zinc and thymulin, had the earliest and highest humoral immune response to SE (p<0.05). This was observed at 2 and 4 weeks after the first vaccination. In addition, the first group had the highest mean thymus weight index, and the highest mean lymphocyte count in the thymus cortex. No significant difference was observed between the first two vaccinated groups in the mean granuloma diameter developed at the two vaccination sites 48 h after administration of the vaccine (p>0.05).

Weaning and the ram-effect on fertility, serum luteinizing hormone and prolactin levels in spring rebreeding of postpartum Awassi ewes.

Spring rebreeding activity was investigated in 44 multiparous Awassi ewes allocated to one of three treatments. The first treatment entailed ewes suckling lambs for 45 days and then continuously exposed to fertile rams (Group 1); ewes of the second group were weaned at 14 days of age and then were either exposed continuously (Group 2) or intermittently (Group 3) to rams. Time of weaning and type of exposure to the ram did not influence the reproductive performance in terms of fertility and prolificacy in postpartum Awassi ewes. Time of weaning did not influence serum LH concentrations monitored at 3h intervals in Groups 1 and 2. However, serum prolactin (PRL) concentrations were significantly higher in Group 1, compared to Group 2 of ewes. Serum LH levels at weaning were significantly higher in ewes that conceived and lambed, compared to ewes that did not. It was concluded that spring rebreeding of postpartum Awassi ewes did not respond to ram presence and/or early weaning in terms of improved reproductive performance. The lack of reproductive response was further reflected in LH and PRL profiles.

Economic sustainability of small ruminants production in semi-arid areas of Lebanon.

Small ruminant production in the near east region is facing serious constraint of feed availability. A study was conducted in marginal areas of Lebanon, using a cost-benefit analysis technique (CBA), to assess the feasibility of four small ruminant production systems ranging from semi-nomadic to settled. When the owned labor cost was included as an opportunity cost in the economic analysis, CBA revealed negative returns in all four systems. Only the settled system was profitable according to the financial analysis excluding labor cost. Moreover, feed expenses if coupled with grazing costs represented a major constraint to profitability. To remedy to the feed deficit problem, the potential of using agro-industrial by-products as feed block supplements was investigated. Simulated feed block diets, using the most available by-products, provided a better nutritive value per unit cost than hand-fed diets used in the systems studied. Preliminary analysis showed that the use of feed block diets could improve the economic sustainability of small ruminant production systems.

Macrophage recruitment and activation: a model for comparing resistance to Salmonella enteritidis in different broiler breeds.

A model for comparing resistance to Salmonella Enteritidis was evaluated in different broiler breeds. The recruitment and phagocytic activity of peritoneal macrophages were assessed in three different broiler breeds (A, B and C) which are farmed world-wide. Assessment was performed after three days of intraperitoneal (i.p.) administration of 3% Sephadex G-200 (10 ml), initiated at twenty-one days of age, followed by contact with i.p. live S. Enteritidis (10 ml, 1.2 x 10(8) colony forming units/ml) for 45 min. Assessment included determination of the number of i.p. macrophages recruited, the number of i.p. phagocytized S. Enteritidis cells per macrophage, the levels of degranulated i.p. beta-glucuronidase and beta-galactosidase, and the count of surviving S. Enteritidis cells. Confirmation of the significance of the model was obtained by comparing resistance to field infection by S. Enteritidis in the three broiler breeds. The recruitment of i.p. macrophages in response to challenge with Sephadex and S. Enteritidis was significantly higher (P < 0.05) in birds of breed A (mean cumulative i.p. macrophage count, in 10 fields of microscopic slide smear magnified at x1,000, was equal to 81.7), compared to recruitment in birds of breed B (33.3) or breed C (41.2). The mean number of phagocytized S. Enteritidis cells per i.p. macrophage in birds of breed A (2.68) was significantly higher (P < 0.05) than in breed B (0.83) and insignificantly higher (P > 0.05) than in breed C (2.35). In addition, the highest level of recruitment and phagocytic activity of macrophages, in birds of breed A, was associated with a higher significant mean i.p. beta-glucuronidase activity (10,425.5 units/ml) than in breed B (3,438.2 units/ml) or breed C (3,356.94 units/ml) (P < 0.05). Moreover, birds of breed A demonstrated a higher mean i.p. beta-galactosidase activity (2.225 units/ml) than birds of breed B (0.852 units/ml) or breed C (1.852 units/ml) (P > 0.05). The higher level of recruitment and activity of i.p. macrophages and the higher rate of degranulation of i.p. enzymes in breed A were associated with a greater number of surviving i.p. S. Enteritidis cells. In response to outbreaks of S. Enteritidis in the field, the average mortality was significantly higher in flocks of breed A (3.2%) than in flocks of breed B (1.2%) or breed C (0.96%) (P < 0.05). These data provide an indication of the significance of the model in reflecting the differences in resistance of S. Enteritidis of broiler breeds reared in a farm environment.

Infection and immunity in broiler chicken breeders vaccinated with a temperature-sensitive mutant of Mycoplasma gallisepticum and impact on performance of offspring.

A comparison of infection and immunity to Mycoplasma gallisepticum (MG) in broiler chicken breeders vaccinated with a temperature-sensitive mutant of MG versus nonvaccinated chickens, and the impact on the performance of their offspring was conducted. Infection and immunity in breeders were assessed by culture and enzyme-linked immunoassay, respectively. However, performance in their offspring was assessed by studying MG infection in embryos, occurrence of infection titers to MG in relation to mortality, and feed conversion in the broilers. Five out of 10 broiler chicken breeder flocks raised on the same multiple-age farm with a long history of mycoplasmosis were vaccinated intraocularly once with a temperature-sensitive MG mutant vaccine (ts-11) at an average age of 7.5 wk; another five breeder flocks were left as unvaccinated controls exposed to field MG. The average recoveries of ts-11 organisms from tracheas and infraorbital sinuses of 41-wk-old vaccinates were 88 and 84%, respectively. No field MG organisms were recovered from vaccinates between 15 and 41 wk of age. The recovery of field MG organisms from tracheas and sinuses of nonvaccinated chickens increased to an average of 100% at 41 wk of age. A significant decrease (P < 0.05) in the average percentage of MG-seroconverted breeders occurred in ts-11-vaccinated flocks in comparison with nonvaccinated, MG-infected flocks at 15, 20, 23, 29, 32, 36, and 41 wk of age. The average infection prevalence by MG in the vitelline membrane of 7-d-old embryos produced by the five unvaccinated breeder flocks peaked at 79% when their respective hatching eggs were collected at 36 wk of breeder's age. Embryos of ts-11-vaccinated flocks had zero prevalence of MG infection at all times between 29 and 57 wk of breeder's age. Seroconversion to MG (average of 17.7%) at 42 d of age was only present in sera of 10 offspring broiler flocks of the nonvaccinated breeders. However, a lack of seroconversion to MG occurred in 10, 42-d-old offspring broiler flocks of the five ts-11-vaccinated breeder flocks. This lack was associated with a lower, better average feed-conversion ratio (2.05) (P < 0.05) and a lower average mortality percentage (5.3%) (P < 0.05) in comparison with those obtained in the offspring of the five unvaccinated, MG-infected breeder flocks. The results indicate that vaccination of broiler chicken breeders with a temperature-sensitive mutant of MG prevented infection by field MG in tracheas and infraorbital sinuses of these breeders and in the vitelline membranes of their embryos. In addition, the broiler offspring of the vaccinated breeders had a better production performance.

Humoral and cell-mediated immunopotentiation in vaccinated chicken layers by thymic hormones and zinc.

The humoral and cell-mediated immunities to a trivalent killed vaccine, administered subcutaneously to white leghorn-chicken layers at 29 and 31 weeks of age, and containing antigens of infectious bronchitis virus (IBV), infectious bursal disease virus (IBDV), and Newcastle disease virus (NDV), were quantitated in five vaccinated and one unvaccinated-control group. Four out of the five vaccinated groups were immunopotentiated by various combinations of zinc and thymic hormones administered intraperitoneally in a volume of 0.1 ml per bird at an interval of three days for a period of three weeks, starting at 29 weeks of age. At each time interval, each bird of the first group received thymulin (10 ng) and ZnCl2 (1 microM), while each bird of the second group received thymopoietin (25 ng) and ZnCl2 (1 microM); in the third group, each bird received thymulin (10 ng), thymopoietin (25 ng), and ZnCl2 (1 microM), while each bird of the fourth group received only ZnCl2 (1 microM). Birds of the fifth group were only vaccinated and the control birds in the sixth group were left without vaccination or other immunopotentiation. Among all combinations, the thymulin-ZnCl2 resulted in birds with the highest humoral immunopotentiation to IBV, IBDV, and NDV antigens with respective percent increase in the mean titer at 33 weeks of age, compared with initial titer at 29 weeks of age, equivalent to 199%, 671.7%, and 86.4%. The highest cell-mediated delayed hypersensitivity reaction, measured at 48 h following an intradermal administration of the trivalent vaccine in the wattles at 33 weeks of age, was obtained in chickens immunopotentiated by the thymulin-thymopoietin-ZnCl2 combination.

Bacterial identity and characteristics in healthy and unhealthy respiratory tracts of sheep and calves.

The aim of this study was to compare different bacteriological aspects of the respiratory systems of healthy (H) versus unhealthy (UH) animals with respiratory signs. The prevalence of different bacterial species was determined in the upper and lower respiratory tract of H and UH Najdi sheep, Somali sheep and Holstein calves. The characteristics of Pasteurella spp. isolates, and the biotype of Pasteurella haemolytica were identified in H and UH animals, Eighteen out of 28 (64.3%) of the identified bacterial species in the upper respiratory tract were more prevalent in the nasal cavities of UH Najdi and Somali sheep and Holstein calves with respiratory signs than in apparently healthy animals; four of the most prevalent bacteria in the upper respiratory system of UH sheep were Moraxella spp., Pseudomonas pseudomallei, Erysipelothrix spp., Pasteurella multocida, while three of the most prevalent bacteria in UH calves were Pasteurella haemolytica, Actinomyces spp., and Pseudomonas aeruginosa. The prevalence of six different bacterial species was greater in the lungs of UH animals, namely Actinomyces pyogenes, Erysipelothrix spp., P. haemolytica, Pasteurella ureae, Staphylococcus aureus, and Staphylococcus epidermidis, which could be risk factors in the complexity of the prevalent respiratory diseases of the animals surveyed. Of the biochemical, cytological and colonial characteristics studied in the identified P. haemolytica and P. multocida, two characters were significantly different (p < 0.05) in organisms isolated from UH as compared to those from H animals. These were the higher loss of haemolytic power by the strains of P. haemolytica and the decreased fermentation of trehalose by all the strains of P. multocida recovered from healthy animals. The only biotype of P. haemolytica isolated from H animals was biotype A, while both biotypes A (88.0% of the isolates) and T (12.0% of the isolates) were recovered from UH animals.

National surveillance of poultry diseases in Lebanon.

From 1992 to mid-1996, a national survey of poultry diseases in Lebanon was conducted. This surveillance included meat breeder, layer breeder, commercial layer and chicken broiler flocks. The history, signs, lesions and laboratory tests of poultry were used in the diagnosis of prevalent poultry diseases. Culture techniques were used to screen for bacterial diseases; serological techniques and, to a lesser extent, culture techniques were used to diagnose viral diseases; and both serological and culture techniques were used to diagnose Mycoplasma infections. The outbreaks of diseases detected in broiler breeder flocks and the number of such flocks experiencing these diseases were as follows: femoral head necrosis (6), egg-drop syndrome (3), reovirus-associated malabsorption syndrome (3), synovitis (Mycoplasma synoviae infection) (7), swollen head syndrome (SHS) (3), tenosynovitis (viral arthritis) (1), lymphoid leukosis (3), avian encephalomyelitis (1), fowl pox (1) and aortic rupture (1). The disease outbreaks detected in layer breeders were as follows: SHS (2), bumble foot (2), egg-drop syndrome (3) and avian infectious bronchitis (IB) (1). The disease outbreaks detected in commercial layer flocks were as follows: egg-drop syndrome (5), avian infectious laryngotracheitis (2), avian IB (nephrogenic strain) (1), malabsorption (1), avian tuberculosis (Mycobacterium avium) (1), Marek's disease (1), fowl pox (1), Salmonella enterica subsp. enterica Enteritidis infection (1), salpingitis (1) and Heterakis gallinae infestation (1). The disease outbreaks detected in broiler flocks were as follows: colibacillosis (40), infectious bursal disease (Gumboro disease) (15), malabsorption syndrome (8), avian infectious laryngotracheitis (8), paratyphoids (salmonellosis) (7), femoral head necrosis (8), SHS (6), avian mycoplasmosis (Mycoplasma gallisepticum infection) (6), synovitis (7), avian IB (6), botulism (1), avian encephalomyelitis (1) and gangrenous dermatitis (1). Diseases which occurred and which were reported for the first time in Lebanon were as follows: bumble foot, femoral head necrosis, avian IB (nephrogenic strain), malabsorption syndrome and SHS. This surveillance helped to establish baseline data concerning the predominant poultry diseases in Lebanon. Such information is a prerequisite for future regional and international collaboration to identify the source of the aetiological agents and to control their spread to neighbouring countries.

Comparison of immunity and resistance to diseases in male and female poultry breeders in Lebanon.

The immune responses following vaccination and resistance to diseases were compared in male and female meat poultry breeders of the same flock. Female poultry breeders maintained antibody titres to Newcastle disease virus and infectious bronchitis virus up to the fifty-fifth day following vaccination, whereas those of the males declined significantly over the same period of time (P < 0.05). In the same flock, outbreaks of Gumboro disease (60 to 62 days of age), coccidiosis (68 to 74 days of age) and aortic rupture (99 to 112 days of age) produced significantly higher losses in males. Following vaccination against fowl pox by the wing web method, 96.7% of females had a vaccine reaction (vaccine take) compared to none of the males. Immune injuries, following vaccination, were observed in 85% of the males compared to none of the females. The immune injuries included appearance of facial papules, vesicles, and reddish brown to black scabs.

Ovarian cyclicity and serum progesterone and luteinizing hormone in fine-wool ewes supplemented with alfalfa or pinto beans.

Effects of season and supplementation on the incidence and rate of ovulation and hormone profiles in multiparous, nonlactating ewes were investigated under range and drylot conditions during anestrus (February through August). Ninety ewes received one of six nutritional treatments: 1) range forage, 2) range forage plus 0.33 kg.hd(-1).d(-1) pinto beans, 3) 0.45 kg.hd(-1).d(-1) alfalfa pellets, 4) dry lot plus 1.33 kg.hd(-1).d(-1) prairie hay only, 5) pinto beans or 6) alfalfa pellets at rates used on the range and prairie hay. Supplemented ewes were heavier (P < 0.05) than ewes fed range forage or prairie hay during most of the study. Seasonality of ovulation, in terms of incidence and rate, was not affected (P > 0.40) by supplementation in range ewes. The ovulation rate tended to be highest in prairie hay plus pinto bean drylot ewes in February (P = 0.21) and in prairie hay plus alfalfa pellet and prairie hay plus pinto bean ewes in March (P = 0.13) compared with prairie hay ewes. Generally, seasonality of ovulation was not influenced by supplementation (P > 0.40). The incidence of ovulation approached zero for drylot ewes in April, May, June and July, while it was 43, 27, 35 and 21% for range ewes, in those same months. Supplementation did not affect serum progesterone during the estrous cycle. Luteinizing hormone (LH) concentrations were similar (P > 0.50) among drylot treatment groups before a 50-ug gonadotropin releasing hormone (GnRH) challenge. Pinto bean supplementation enhanced serum LH response to GnRH (P < 0.10).