Soybean meal (SBM) is a staple proteinaceous feedstuff in diets for monogastric animals like poultry and swine. It is known that soybeans contain several anti-nutritional factors that, if untreated, results in decreased quality and bioavailability of amino acids (AA). Thermal processing via heat treatment of soybeans and SBM is essential for inactivation of these anti-nutritional factors; however, over-processing may result in extensive AA damage, particularly lysine. Feeding heat damaged SBM has been proven to be an inefficient source of AA for monogastrics as they cannot be used for any metabolic function. In typical corn-soybean meal diets for pigs and poultry, lysine is the first- and second- limiting AA, respectively. Currently, laboratory procedures are unable to accurately determine digestible lysine in SBM. The objective of this thesis was to compare SBM AA digestibility obtained from 28-day old broilers to values obtained from an in vitro digestion procedure. The correlation between AA concentration in the SBM and its in vivo standardized ileal digestibility (SID) was also analyzed. Twenty-four SBM samples (21 from U.S.A., 2 from Canada, and 1 from Mexico) were analyzed. In vivo lysine SID ranged from 69-93%. Results indicated no correlation (r = -0.16 to 0.21; P = 0.33 to 0.98) between analyzed AA content in SBM and in vivo SID. An increase in lysine SID was associated with an increase in the SID of phenylalanine, leucine, isoleucine, valine, tyrosine, alanine, threonine, glutamate, aspartate, methionine, histidine, and glycine (r² = 0.63 to 0.93; P < 0.001). Poor association was determined between lysine proline, arginine, and serine (r² = 0.14 to 0.43; P = 0.001 to 0.003). Lastly, results indicated no association (r² = 0.00 to 0.08; P = 0.17 to 0.99) between in vivo and in vitro SID for any of the AA tested. In summary, it appears that lysine may be a good indicator for SID estimations for most essential AA; however, SBM content of a particular AA is not a good indicator of its digestibility. Additionally, current in vitro digestibility techniques seemed inadequate in identifying in vivo SID differences and further analytical improvements are needed. / Master of Science

A southern Mississippi broiler complex in an area of high poultry density experienced persistent lower livability and growth performance compared with company averages for the state. It was hypothesized that circulating Infectious Bronchitis Virus (IBV) challenge exacerbated by underlying Infectious Bursal Disease (IBD)-induced immune suppression was the primary contributor to reduced livability and live production performance on certain farms, and that disease challenges were most prevalent on farms in areas of high bird density. A retrospective analysis of data from a three-year period (March 2014 through March 2017) was designed to investigate the role of disease, settlement, geographic, and weather variables in broiler mortality. A database comprising diagnostic variables (processing-age ELISA titers for Infectious Bursal Disease (IBD), Infectious Bronchitis Virus (IBV), Newcastle Disease Virus (NDV), and Reovirus (REO)), settlement variables (downtime, age at processing, average weight at processing, week 1 mortality, genetic line, year, and broiler vaccination programs), geographic variables (number of commercial chicken farms and houses within 1 km, 5 km, 10 km and 15 km radii), and weather variables (average temperature, average heat index, and average humidity for the first 7 days and last 14 days of grow-out) was created and analyzed using univariable and multivariable statistical analyses. First-week mortality, processing age, average processing weight, genetic line, NDV/IBV vaccination program, and heat index in the last 14 days of the grow-out period were found to be significantly associated with flock mortality in this broiler complex (P <= 0.05). The results of this study should guide future management and disease control strategies aimed at reducing broiler mortality. Future studies with more diagnostic data are needed to further investigate the relative contribution of diseases to broiler flock mortality.

Controlling pathogenic presence in broilers has become a priority in the poultry industry to prevent economic losses due to disease and infection, as well as the possible contamination of chicken products. The use of antibiotics reduces the incidence of infections; however, their removal from production initiated the search for suitable alternatives. Probiotic ineed supplements have been widely evaluated as alternatives. Probiotic use has improved broiler performance, reduced pathogenic loads, and stimulated the immune system at later life stages. However, there is still a gap in protection during the first weeks after the chick hatches. The in ovo supplementation of probiotics has the potential of promoting early health benefits and protect the chick against pathogens after hatch. In the present study, the in ovo inoculation of different probiotic species was evaluated. It was determined that the inoculation of higher concentrations of E. faecium (107 cfu/50µL) into the egg improves growth performance and intestinal morphology compared to lower doses (105 and 106 cfu/50µL). It was also determined that not all B. subtilis serotypes are safe for in ovo inoculation, even if recognized as safe for use in feed, due to a high reduction in hatchability. However, certain B. subtilis are safe for in ovo inoculation and regulate the gut microflora through modulations in coliforms and aerobic bacteria after hatch. Lastly, the in ovo inoculation of different Lactobacillus strains does not affect hatchability or growth performance. However, different Lactobacillus species stimulated cytokine production even during the first week of hatch. The bursa of Fabricius morphology was modulated through an increase in follicular area, which could possibly induce higher antibody production against incoming pathogenic challenges. These results indicate that the in ovo inoculation of probiotic bacteria can induce earlier benefits to broiler health through early changes in gut microflora, as well as early stimulation in the immune system. The early protection provided through the in ovo inoculation of probiotics combined with the protection obtained through the administration of probiotics in feed could potentially result in overall healthier broilers and therefore improved performance.

The objectives of this study were first, to investigate the effect of stress and ascorbic acid (AA) supplement during stress on intestinal microflora of broilers and layers, and secondly, to determine nitric oxide (NO) production in intestinal tract of broilers during stress, when supplemented with L-arginine, and NO production in cecal bacteria. The intestinal microflora from broilers and layers were analyzed for bacterial populations during stress and when supplemented with ascorbic acid. In both studies, stress response was induced by adrenocorticotropic hormone (ACTH) via a mini osmotic pump for 7 days, and intestinal samples were collected before and after stress response was induced. During stress, there were no significant effects on intestinal bacterial populations, but changes in intestinal microflora were found in stressed layers and broilers. When AA was supplemented during stress, both short-term and long-term, the microbial population was changed. Cecal NO production during stress, cecal bacterial NO production, and large intestinal NO production when L-arginine was supplemented in broilers were determined as nitrite using Griess reagents. The stress response was induced as in the previous studies. The cecal pouches were collected at day 7 after ACTH insertion. Nitric oxide production by the ceca of broilers during stress was decreased. The cecal bacterial NO production was determined in vitro. The cecal bacteria that produced NO were identified as Lactobacillus fermentum, and Clostridium butyricum. Supplementing with L-arginine, Nù -nitro-L- arginine methyl ester (L-NAME), and sodium nitrate did not affect bacterial NO production on MRS agar incubated anaerobically, but sodium nitrate did affect bacterial NO production on tryptic soy and anaerobic agar incubated aerobically and anaerobically, respectively. L-arginine was supplemented in broiler diet to determine the effect on intestinal NO production and microbial populations. Supplemented with L-arginine affected cecal NO production, but did not affect large intestinal NO production or microbial populations. The positive correlation coefficient between NO contents and bacterial populations was only observed in the large intestine when L-arginine was supplemented in the diet.

No description available.

Previous research evaluated the dLys requirement and the impact of varying dLys and AME on Cobb MV x Cobb 500 broilers during the starter and grower phases, leaving the finisher phase to be determined. Experiment 1 estimated the finisher dLys requirement to range from 0.748-1.32% for males and 0.752-1.292% for females. Male broilers were more responsive to increasing dLys than females, though in general, increasing dLys improved performance and processing. Experiment 2 determined the effects of varying finisher dLys and AME on broiler performance and processing. Increasing dLys improved BWG, FCR, ALI, and breast yield while decreasing FI and fat pad yield. Increasing AME consistently reduced FI and FCR while increasing thigh and fat pad yield. Economic analyses for both experiments demonstrated that maximizing performance was not always economical, verifying the importance of considering feed costs and performance to optimize return on investment for Cobb MV x Cobb 500 broilers.

The role of nutrition in providing optimal broiler growth and intestinal health is essential, especially during stress or disease challenge. Feed enzymes are useful for improving performance of poultry, particularly when nutrition, management, or health status is not favorable. The objective of the following experiments was to evaluate the effect of dietary phytic acid (PA) and phytase on the performance and intestinal health of birds that were vaccinated with a live coccidial oocyst vaccine. For each experiment, half of the chicks were spray-vaccinated at day-of-hatch with Coccivac®-B and grown out in floor pens with ad libitum access to diets formulated to meet Cobb nutrient recommendations. In the first experiment, birds were given one of three diets that included different levels of a PA solution to obtain dietary PA levels of 0.74, 0.87, and 1.12% for low, medium, and high PA diets, respectively. In the second experiment, two levels of PA were included to obtain dietary PA levels of 0.75 and 1.05% for low and high PA diets, respectively. In addition, phytase was added over the top to half of the diets at 1000 FTU/kg, resulting in four diets: low PA without phytase, low PA with phytase, high PA without phytase, and high PA with phytase. Live performance parameters including body weight, body weight gain, feed intake, feed conversion, and mortality were measured as well as tibia ash (experiment 2) and indicators of small intestinal health including morphology, apparent ileal amino acid digestibility (IAAD), and pH (experiment 2). The results presented here indicated that giving broilers vaccinated against coccidiosis a medium level of PA was detrimental to feed intake, body weight gain, and it induced necrotic enteritis (P ≤ 0.05). Adding phytase on top of nutritionally adequate diets did not improve performance (P ≥ 0.05), but did improve (P ≤ 0.05) apparent IAAD and morphology of the small intestine, especially in younger birds. In addition, it has been determined that important considerations in diet formulation also can include the phytate: protein as well as calcium: total phosphorus ratios, as these may critically affect how phytate impacts bird health and performance. / Ph. D.

A series of experiments were conducted to investigate the effects of certain biological, nutritional, and processing factors on breast meat quality of broilers. In the first experiment, the influence of genetic strain, plane of nutrition, and age at slaughter on breast meat quality was evaluated. Breast meat from a high yield line of broilers had lower pH at 24 h postmortem (PM), greater L*, a*, and b* values, lower water holding capacity (WHC), and higher expressible moisture (EM) than those of a line selected for rapid growth. Breast meat from birds processed at 42 d had lower WHC than those processed at 53 d, even though no differences in pH and L* values at 24 h were observed. No significant effects due to plane of nutrition on meat quality traits were observed. In Experiment two, the influence of strain and chilling methods (ice or air chilled) on breast meat quality was studied in broilers. Breast meat quality significantly differed among strains, with one of the strains evaluated having higher muscle pH, lower L* values, and higher WHC than the other strains. Ice-water chilling significantly reduced the rate and extent of PM pH decline, but had significantly lower WHC and higher EM than those from carcasses chilled by air. However, chilling conditions did not influence breast meat color. In Experiment three, the effects of strain and gender on breast muscle quality of broilers was studied. Meat quality traits were evaluated on both sexes of six genetic crosses of commercial strains. No significant differences in breast meat quality traits among strains were observed. However, differences between sexes were highly significant. The P. major muscles of females had lower pH values at all PM times, higher L*, a*, and b* values, and lower WHC than males. The P. minor of females had significantly lower pH, lower WHC, higher EM, but similar color L*, a*, and b* values than males. In Experiment four, the effects of strain, gender, and age at slaughter on breast meat quality were studied. Strain differences were observed in both sexes, but these differences did not show any specific relationship with the strain genotype. Breast muscles from a male pure line had superior meat quality, with higher muscle pH, and WHC, but higher L* values than the other strains. Significant differences in breast meat quality traits due to age at slaughter were also observed. Regardless of gender, breast muscle pH at 24 h PM and WHC decreased linearly with age, while breast muscle temperature and L* values increased in a linear fashion with advancing age at slaughter. No significant strain by age interactions were observed for any of the meat quality traits evaluated. The results of these studies indicate that commercial genotypes differ significantly in PM muscle metabolism and subsequent meat quality. The results also indicate that female broilers and older birds might be more susceptible to meat quality problems. / Ph. D.

A study was carried out to investigate the effects of a drug-free feeding program on broiler performances. A total of 2,496 Cobb 500 chicks were randomly assigned to one of four dietary treatments with each group replicated 13 times. The four diets evaluated were: 1) negative control (NC): basal diet without growth promoter or coccidiostat; 2) positive control (PC): diet 1 + Lincomycin; 3) Program 1 (PG1): diet 1 + Bio-Mos®, Vegpro®, MTB-100®, Acid Pak 4-Way®, and All-Lac XCL®; 4) Program 2 (PG2): diet 1 + Bio-Mos® and All-Lac XCL®. Additives were used at commercially recommended rates. All chicks were vaccinated with a live oocyst coccidia vaccine on d 0 at the hatchery. Four phases of feeding were used during the trial with changes occurring at d 14, 28, and 35. Performance values measured were body weight, feed intake, yield, and mortality, while body weight gain and feed conversation rate (FCR) were calculated. Chicks were challenged with coccidia at d 14 to evaluate the protective effect of the feeding programs and coccidia vaccination. Segments of duodenum, ileum, and ceca were removed to measure intestinal morphology. Final body weight gains of birds on PC (2.736 kg) were greater (P < 0.05) compared to NC (2.650 kg), while birds on PG1 (2.681 kg) and PG2 (2.710 kg) were similar to positive and negative control. Overall, feed intake was similar across the treatments with the exception of period 2 (15 to 28 days) when birds consumed more (P < 0.05) of PC and PG1 compared to NC. Cumulative FCR at d 35 and 49 was improved (P < 0.05) in birds consuming PC and PG2 when compared to NC. Overall, birds consuming NC had greater mortality (P < 0.05; 12%) compared to PC (7.6 %), PG1 (4.6%) and PG2 (6.7 %) with most of the mortality occurring from d 0 to d 28. Mortality for birds consuming PG1 was also lower (P < 0.05) compared to the PC. There were no dietary effects on lesion scores or yields of processed products at d 42 (females) or d 49 (males). Interaction of dietary treatments with age and days of age alone showed effects (P < 0.0001) on the morphology of duodenum, ileum, and ceca. Lamina propria in ceca was thicker (P < 0.008) in birds consuming NC compared to PG1 and PG2. This study indicated that feeding birds without growth promoters resulted in greater mortality and decreased performance compared to using an antibiotic, while Bio-Mos® in combination with All-Lac XCL® helped to reduce the negative effects. / Master of Science

A study was conducted to investigate the effects of roxarsone and Bio-Mos® on broiler production, gut morphology and bone strength. Three thousand and ten broilers were randomly assigned to 1 of 5 dietary corn-soybean meal based treatments: 1) negative control (NEG), basal diet; 2) positive control (POS; NEG + 27 ppm Bacitracin MD); 3) roxarsone (ROX; POS + 50 ppm of roxarsone); 4) Bio-Mos® (BIO; POS + 0.15 and 0.5% Bio-Mos® added during the starter and grower periods, respectively); 5) Bio-Mos®+All-Lac XCL (BIO+LAC; POS + 0.2, 0.1, and 0.05% Bio-Mos® during the starter, grower and finishing periods, respectively and 0.25g All-Lac XCL/bird sprayed at hatchery). On day 14, 7 of the 14 replicate pens/treatment were challenged with Eimeria maxima (3 x 104 oocysts/bird). Tibias were collected on day 28 and 49 to determine bone-breaking strength. Non-challenged birds had higher body weight gains (BWG) and lower feed conversion (FCR) from day 0 to 49 than challenged birds (P < 0.05). Jejunal crypt depth was increased in challenged broilers compared to non-challenged broilers at 28 days-of-age (P < 0.05). From day 0 to 35, ROX birds had lower BWG and FI than BIO and BIO+LAC birds (P < 0.05), while FCR was similar. Supplementing roxarsone resulted in reduced feed intake and BWG, but no significant differences were noted in FCR compared to feeding Bio-Mos®. ROX fed broilers had decreased ileal crypt depth compared to all other dietary treatments (P < 0.05). Muscle As concentration was lower than FDA allowable limits in broilers fed ROX without a withdrawal period at 28 days-of-age. Including roxarsone or Bio-Mos® did not generally improve production compared to broilers fed the negative diet. / Master of Science