Holo-analysis of the efficacy of Bio-Mos in broiler nutrition

1. This first holo-analysis of the efficacy in broiler nutrition of the saccharide product, Bio-Mos(R) (BM), is part of a comprehensive empirical modelling research programme quantifying and comparing the efficacies and future research needs of the diverse candidates offered as replacements for antibiotics. 2. The data used are from 32 publications with broiler performance data from a world-wide literature collection of 124 (1997-2003) on the use of BM as a broiler feed additive. It contains the results of 82 negatively controlled feeding tests from 21 countries using a total of 85 142 broilers, averaging 401 per treatment. 3. The 82 feed intake, liveweight gain, feed conversion ratio and 44 mortality responses to BM average -12.2 g, 27.6 g, -0.0391 and 0.0311%, respectively, with coefficients of variation of 828, 227, 192 and 8392%. Respective beneficial response frequencies for gain, conversion and mortality are 65, 70 (52% jointly) and 52%. 4. Holo-analytical multiple regression models were elaborated for the effects of BM on feed intake, liveweight gain, feed conversion ratio and mortality, using conventional Por=0.10 out and less stringent Por=0.34 out partial regression coefficient standards, with and without>or=3xroot mean square error outliers, in order to quantify the influences of negative control performance, test duration, BM dosage, cage housing, processed feed, antibiotic feed, year of test and USA test. To date they account for only 5-36% of response variations, due primarily to 52 of the 82 tests having no reported feed formulations. 5. These exploratory models confirm beneficial responses to BM for current broiler performance levels. They also indicate a need to clarify BM dose-response relationships in order to maximise efficient use in praxis and to facilitate cogent comparisons with other pronutrients, including other saccharide products.     

Mechanistic modeling of turkey growth response to genotype and nutrition

Along with the fast genetic improvement, nutritional and environmental effects on poultry growth performance have made it necessary to develop growth models that have the flexibility to adapt to different genotypes and growing conditions. A mechanistic simulation model of energy and nutrient utilization in growing turkeys is presented herein. The model consists of simulating the average homeorhetic and homeostatic regulations associated with the utilization of circulating glucose, fatty acid, AA, and acetyl-CoA for protein and lipid retention in carcass, viscera, and feathers in a turkey population. Homeorhesis plays a major role in the control of protein and lipid turnover for the definition of genetic potential and feed intake, whereas homeostasis adjusts growth rate through protein and lipid turnover rates and, therefore, BW gain and feed intake to the growing conditions. Also, homeostasis enables the maintenance of a dynamic balance state during all the growing period through the control of circulating nutrient concentration. The model was developed and calibrated with experimental data that described energy utilization in male and female growing turkeys. Then, the ability of the model to adapt to genotypes and to predict the average response of a turkey population to dietary energy was evaluated. Model calibration showed simulations of energy and nutrient utilization that fitted well with the experimental data because ME was satisfyingly partitioned into heat production and energy retention as protein and lipid, and nutrient intake accurately partitioned BW gain into carcass, viscera, and feathers. The evaluation of the model was also satisfactory because BW gain and feed-to-gain ratio were globally in accordance with the observations in different male and female genotypes, in spite of an overestimation of the feed-to-gain ratio during the first weeks of age. Model evaluation showed that the BW gain and feed intake response of growing turkeys to dietary energy was accurately predicted. The model can therefore be used in different growing conditions as it is capable of simulating the growth of different turkey genotypes fed under changing environmental and nutritional contexts.     

Effect of aflatoxin B1 on the efficacy of turkey herpesvirus vaccine against Marek's disease

The effect of feeding aflatoxin B1 (AFB1) (0.5 ppm) was studied in young chicks. The frequency and the severity of gross and microscopic lesions of Marek's disease were significantly higher in those birds which had been vaccinated with turkey herpesvirus (HVI) and birds challenged with Marek's disease virus which had been given AFB1 in the feed than in those given normal feed. The protective efficacy of HVT vaccine, as judged on the basis of gross and histopathological lesions, was 86.1 and 77.3 per cent in normally fed birds in comparison to 37.6 and 8 per cent in AFB1 fed birds.     

A comparison of the efficacy against Marek's disease of cell-free and cell-associated turkey herpesvirus vaccine.

One-day-old White Leghorn and broiler chicks with maternal antibody to turkey herpesvirus (HVT) were vaccinated with 300 or 1,000 plaque-forming units (PFU) of cell-free or cell-associated HVT vaccine and challenged with virulent Marek's disease virus (MDV) by contact exposure. Broiler chicks receiving 300 PFU of cell-associated HVT had a 3.3% incidence of MD lesions, whereas only 2.0% of those receiving 1,000 PFU had macroscopic lesions. Broiler chicks vaccinated with 300 PFU of cell-free vaccine had 6.8% gross lesions, and 0.67% of the birds receiving 1,000 PFU had MD lesions. Unvaccinated broiler chickens had a 28.3% incidence of MD lesions. Unvaccinated White Leghorn chickens had a 48.9% incidence of macroscopic lesions, whereas 5.4% of the birds receiving 300 PFU of cell-associated HVT had gross lesions, and 8.3% of the birds vaccinated with 1,000 PFU had lesions. In contrast, 6.7% of the chicks vaccinated with 300 PFU of cell-free HVT had MD lesions, and only 4.0% of those receiving 1,000 PFU of cell-free HVT had macroscopic lesions.     

Anticoccidial efficacy of diclazuril against recent field isolates of Eimeria from turkey farms in the United States.

In a series of laboratory tests, diclazuril was evaluated for efficacy against Eimeria adenoeides, E. meleagrimitis, E. gallopavonis, and a mixture of the three species. Four isolates of each of the species were tested. When given at 0.5, 1.0, and 1.5 ppm in the feed, diclazuril was highly efficacious against all three species and against mixtures of the three, as judged by protection against mortality from coccidiosis, reduction in droppings scores, and improvement of weight gains compared with unmedicated controls. When diclazuril was given at 1.0 ppm, the improvement in droppings scores and weight gains was better than when 0.5 ppm of diclazuril was given. Increasing the dosage to 1.5 ppm did not appear to offer any consistent or significant improvement over 1.0 ppm.     

Pharmacokinetics of penicillin G in the turkey

Parmacokinetics of penicillin G was determined for the turkey. The study was prompted by the isolation of a sulfonamide-resistant strain of Pasteurella multocida from tissues of turkeys involved in an outbreak of fowl cholera and the subsequent discovery that little pharmacologic information was available concerning other antimicrobial agents in that species. Penicillin G was chosen for study because P multocida is susceptible to this antibiotic. The elimination of the antibiotic followed first-order kinetics, and the half-life was found to be 0.5 hours. Parenteral administration of benzathine-procaine penicillin G resulted in higher concentrations, which persisted for longer periods than did procaine or potassium salts of the antibiotic.     

Specific mucosal IgA immunity in turkey poults infected with turkey coronavirus

The objective of this study was to elucidate the kinetics and magnitudes of specific IgA antibody responses in intestines of turkey poults infected with turkey coronavirus (TCV). Turkey poults were orally inoculated with TCV at 10 days of age. Intestinal segment cultures were administered for duodenum, jejunum, and ileum and the IgA antibody responses were analyzed at 1, 2, 3, 4, 6, or 9 weeks post-infection (PI) in two different experiments. The kinetics of virus-specific IgA antibody responses in duodenum, jejunum, and ileum were similar: gradually increased from 1 week PI, reached the peak at 3 or 4 weeks PI, and declined afterward. The virus-specific IgA antibody responses in duodenum, jejunum, and ileum showed negative correlation with duration of TCV antigen in the corresponding locations of intestine with Spearman's correlation coefficient of -0.85 (p=0.034), -0.74 (p=0.096), and -0.75 (p=0.084), respectively. Moreover, the virus-specific IgA antibody responses in serum were positively correlated with that of duodenum (coefficient=0.829, p=0.042), jejunum (coefficient=0.829, p=0.042), and ileum (coefficient=0.771, p=0.072) segment cultures, suggesting that the induction of specific IgA response in serum was predictive of an IgA response in intestine. The results indicate that intestinal mucosal IgA antibodies to TCV are elicited in turkeys following infection with TCV. The local mucosal antibodies may provide protective immunity for infected turkeys to recover from TCV infection.     

Rickets in turkey poults

Fifteen outbreaks of rickets were diagnosed in turkey poults in Saskatchewan between 1978 and 1981. No relationship to farm, source of poults, or source of feed was apparent. Most outbreaks started when the poults were between 10 and 14 days of age, and they had recovered by 28 days of age. Losses varied from 1% to 14% of poults started. Skeletal lesions were characteristic of a vitamin D or calcium deficiency. On the basis of chemical analyses, adequate levels of calcium and phosphorus and proper amounts of vitamin premixes were present in the feed, but in five outbreaks biological feed tests implicated feed as a causative factor. The severity of rickets in poults fed defective feeds was markedly reduced by providing the poults with extra vitamin D in the drinking water or by injection. Two premixes used in different feeds contained adequate available vitamin D on the basis of biological testing. In some of the outbreaks, the rickets may have resulted from inadequate distribution of vitamin D in the feed, destruction of vitamin D during feed processing, or some unknown factor in the feed interfering with vitamin D utilization.     

Immunocompetent cells of the turkey: antigenic surface determinants of turkey lymphoid cells.

The serologic properties of chicken antiserums to turkey bursa and thymus were assayed by the cytotoxicity tests and indirect immunofluorescence. The following antigenic surface determinants were detected, using proper absorptions on thymic and bursal lymphoic cells: (a) common lymphocyte antigens present on both kinds of cells, (b) thymus-specific antigens, (c) bursa-specific antigens, and (d) immunoglobulin surface determinants in bursa cells, as revealed by direct immunofluorescence.     

Myiasis in a turkey

A case of cutaneous myiasis was reported in a 3.5-month-old turkey. The bird was invaded by a very large number of maggots on its posterior half. The maggots killed the bird and consumed all the flesh within 48 hours. Microscopic examination of the maggots revealed that they belonged to Lucilia sericata (a dipterous fly). The incidence of myiasis in birds was also discussed.     

Efficacy of a commercial turkey coryza vaccine (Art-Vax) in turkey poults

Four laboratory experiments were designed to study the efficacy of the only available commercial vaccine for turkey coryza, Art-Vax. Poults were vaccinated either once or twice at different ages and challenged with pathogenic Alcaligenes faecalis. In another study, commercial turkeys vaccinated at 1 and 12 days of age on a commercial farm were brought to the laboratory for challenge with pathogenic A. faecalis. Both the laboratory- and field-vaccinated poults were given the manufacturer's recommended dosage of the vaccine strain. Regardless of the vaccine schedule or source of poults, the vaccine was not effective in protecting challenged turkeys from infection. Furthermore, the vaccine was not effective in protecting poults less than 3 weeks of age from disease, but it was effective in protecting poults more than 3 weeks of age from disease. These results indicate that although vaccinated turkeys older than 3 weeks of age were not susceptible to disease, they were susceptible to infection and could act as carriers of field strains of A. faecalis, thus perpetuating the risk of infection to flocks subsequently raised in the same buildings.     

Sodium requirement of the turkey hen

Two experiments were conducted to determine the sodium requirement of the Large White turkey hen. A supplementation rate of 0.59 g sodium/kg diet (1.0 g sodium/kg in total) was required for maximum production when the hens were fed a maize-soyabean meal diet. The egg production of hens receiving a diet without added sodium had fallen to zero after 70 d. After 1.18 g sodium/kg was added to the diet 40% of hens returned to production within 14 d.