Massey Documents by Type

Permanent URI for this communityhttps://mro.massey.ac.nz/handle/10179/294

Browse

Subject: search.filters.subject.Broilers (Chickens)

Search Results

Now showing 1 - 7 of 7
  • Thumbnail Image
    Item
    Investigations on black soldier fly (Hermetia illucens L.) production and nutrition : a sustainable solution for poultry feeding : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science, School of Agriculture and Environment, College of Sciences, Massey University, Palmerston North 4442, New Zealand
    (Massey University, 2024-08-20) Mahmoud, Amira Elsayed Abdalla
    Black soldier fly (BSF; Hermetia illucens L.) is renowned for efficiently converting organic wastes into valuable biomass rich in protein and fat. This makes it a profitable and sustainable method for waste management and a useful feed source for animals like poultry, fish, pigs, and pets. Using BSF reduces the dependence on traditional feed ingredients such as soybean and fish meal, which are often imported and add to the carbon footprint. Despite growing interest and large-scale production of BSF meals, knowledge gaps hinder the widespread adoption of this technology, especially in small and medium-scale operations. The overall aim of this multidisciplinary research was to better understand the biology and rearing methods of BSF, processing of insect meals, and their utilisation by broiler chickens. The thesis research specifically investigated: (1) methods and techniques that optimise BSF breeding and meal processing relevant to small and medium-sized operations, (2) the impact of substrate type, moisture, and compaction on the non-feeding stages of BSF, (3) disease management in BSF colonies to ensure healthy population dynamics, including the first record of red mites as a parasitic case within BSF colonies, and (4) the nutritional value of the larval and pre-pupal stages of BSF as replacements for soybean meal (SBM) in poultry feeds. Firstly, the thesis provided a practical guide to establishing and managing a BSF colony, covering the entire process from egg production to larval and pre-pupal meal processing. The procedures were based on the experience of producing 450 kg of BSF larvae (BSFL) and pre-pupae (BSFP) over the course of doctoral research. Secondly, a study examined the impacts of substrate type, moisture levels, and compaction on BSF pupation success, adult emergence and morality. Among the six substrates evaluated (sand, wood shavings, topsoil, vermiculite, spent wheat middlings, and potting soil), spent wheat middlings presented as the most cost-effective and readily available option. Moisture level was found to significantly affect substrate performance, with 10% moisture providing the best outcomes for pupation and reducing mortality while avoiding mould growth. Mild compaction did not negatively impact pupation development, suggesting that moderate compaction could enable small farmers to reuse substrate and lower the cost. Thirdly, an infestation of poultry red mites (Dermanyssus gallinae), causing noticeable skin discoloration and anatomical damage to the BSFL and BSFP, was identified. The mites repeatedly bit and fed on the BSF bodily fluids, causing distress. The implications of mite infestation on colony health and viability are discussed, emphasising the need to maintain colony hygiene. Lastly, the apparent metabolisable energy (AME) and standardised ileal digestibility coefficients (SIDC) of amino acids (AA) of full-fat BSFL and BSFP meals for broiler chickens were determined. The AME and SIDC of BSFL and BSFP were higher than those reported for SBM, the commonly used protein meal in poultry diets. The findings demonstrated that BSFL and BSFP meals are better sources of energy and digestible AA, and are potential substitutes for SBM. Although the principles behind BSF bioconversion technology may seem straightforward, effective implementation requires deeper understanding of its complex stages. The present thesis provided a thorough overview of BSF technology, including rearing methods, optimising pupation conditions, the identification of a novel ectoparasite affecting BSF colonies, and the potential use of BSFL and BSFP into broiler chicken diets. By addressing these key aspects, the research contributes valuable insights for optimising BSF production and utilisation, particularly for small and medium-scale operations.
  • Thumbnail Image
    Item
    Molecular epidemiology of Salmonella in the broiler industry of Sri Lanka : thesis presented in fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science at Massey University, Palmerston North, New Zealand
    (Massey University, 2021) Liyanagunawardena, Nilukshi
    The increasing occurrence of non-typhoidal Salmonella in poultry is an emerging threat for public health in Sri Lanka, and salmonellosis has incurred massive economic loss for the poultry industry in the country. Thus, the thesis presented encompasses a comprehensive study to understand prevalence and possible risk factors for Salmonella carriage in broiler farms as well as whole-genome sequence-based population structure, phylogenetic relationships and antimicrobial resistance in Salmonella in Sri Lankan poultry. The studies described in this thesis include a cross-sectional survey (i.e., sampling and questionnaire-based study) conducted from July to December 2017 in broiler farms (115) from poultry-dense areas and associated hatcheries (15) as well as an outbreak study (from 2010 to 2018), based on isolates and metadata from poultry salmonellosis outbreaks. After initial identification and PCR confirmation of a total of 164 Salmonella isolates, whole-genome sequencing was performed and antimicrobial resistance profiles of the isolates were determined. Results revealed a Salmonella prevalence of 32.2%, CI 95% [23.6-40.7] in broiler farms and 66.7%, CI 95% [42.8-90.5] in the associated hatcheries. Litter management, rest period between flocks, feed storage, district and farmers’ knowledge of sick birds were identified as risk factors for Salmonella carriage in the broiler farms, through multivariate logistic regression modelling. Eighteen different multi-locus sequence types of Salmonella were identified, including nine which were reported for the first time in Sri Lankan poultry. The most common serovars were S. Kentucky ST314 (26.8%, CI 95% [20.0-33.6]) and S. Enteritidis ST11 (19.5%, CI 95% [13.4-25.6]). A high percentage of quinolone resistance manifesting as resistance to nalidixic acid (41.5%, CI 95% [33.9-49.1]) and intermediate resistance to ciprofloxacin (45.1%, CI 95% [37.5-52.7]) and enrofloxacin (35.4%, CI 95% [28.0-42.7]) was found. The findings of this thesis, especially in the absence of previous comprehensive studies, will enable the design of control strategies to strengthen the national Salmonella control programme in Sri Lanka.
  • Thumbnail Image
    Item
    Influence of feed form and age of broilers on energy utilisation of feed ingredients : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science (Poultry Nutrition) at Massey University, Palmerston North, Manawatu, New Zealand
    (Massey University, 2022) Khalil, Mahmoud Mohamed
    The accurate determination of the available energy of feed ingredients is crucial to optimise their inclusion in feed formulations and to improve the profitability and sustainability of poultry production. The metabolisable energy (ME) is commonly used for energy evaluation and formulating the diets for poultry. However, there are some limitations and several factors that influence the precision of the evaluation of the ME content of feed ingredients and diets. The current thesis investigated some of the unexplored research gaps on the ME of the commonly used feed ingredients in broiler diets. The first study presented in Chapter 3 was conducted to investigate the influence of feed form (FF; mash vs. pellet) on the apparent metabolisable energy (AME) and nitrogen-corrected AME (AMEn) of 7 single feed ingredients, four cereal grains (wheat, sorghum, barley, and maize) and three protein sources (soybean meal; SBM, canola meal; CM, and meat and bone meal; MBM). The influence of broiler age AMEn of cereal grains was investigated in Chapter 4 (direct method) and Chapter 5 (substitution method). The fourth experiment reported in Chapter 6 examined the effect of broiler age on the AMEn of protein sources. The experiments discussed in Chapter 7 were unique in that a novel methodology was developed for the quantification of the ileal endogenous energy losses (IEEL) in broiler chickens and for the correction of apparent ileal digestible energy (AIDE) to true (TIDE) ileal digestible energy of cereal grains (wheat, sorghum, barley and maize). The last trial of the thesis reported in Chapter 8 was conducted to refine-tune the IEEL methodology developed in Chapter 7 and to determine the influence of age and dietary cellulose contents on the IEEL estimates in broiler chickens. Data reported in Chapter 3 demonstrated that FF influenced the AMEn of feed ingredients. Pelleting increased the AMEn of all cereal grains by an average of 0.22 MJ/kg. However, for protein source ingredients, FF influence was ingredient-dependent. Pelleting increased the AMEn of CM by 0.57 MJ/kg, had no effect on that of SBM and decreased the AMEn of MBM by 0.56 MJ/kg. The experiment reported in Chapter 4 investigated the influence of broiler age on the AMEn of cereal grains using the direct method. The assay diets were formulated with an inclusion of 962 g/kg of each grain in the diet and pelleted. The data revealed that the age of broiler chickens has a significant impact on the AMEn of cereal grains. The first week of age recorded the highest AMEn for all cereal grains. Thereafter, the AMEn decreased either linearly (sorghum) or quadratically (wheat, barley and maize) with the advancing age of broilers. In the study reported in Chapter 5, the effect of broiler age on the AMEn of cereal grains, from the same batches used in Chapter 4, was examined using the substitution method. A maize-SBM basal diet was formulated and test diets were developed by replacing (w/w) 300 g/kg of the basal diet with each cereal grain. The results showed that the effect of broiler age on the AMEn varied depending on the grain type. Whilst the AMEn of barley and maize were unaffected by age, the AMEn of wheat and sorghum increased with the advancing age of broiler chickens. The determined AMEn values differed between direct and substitution methods, with the substitution method generating lower AMEn values. Data reported in Chapter 6 demonstrated that the AMEn content of SBM and CM was influenced by age of broilers. The first week showed the highest AMEn value for both SBM and CM, followed by reductions for both ingredients up to week 3 and increases thereafter. The studies reported in Chapter 7 present a novel approach to quantify the IEEL in broilers and correct the AIDE of cereal grains (wheat, sorghum, barley and maize) to TIDE enabling comparisons with AMEn. The IEEL was estimated to be 1.45 MJ/kg dry matter intake (DMI) in 21-d old broilers, following the feeding of a glucose-based purified diet and used to calculate the TIDE. The apparent ileal digestibility of dry matter, nitrogen and starch were positively and highly correlated with the TIDE than the AIDE or AMEn. The studies reported in Chapter 8 were conducted to refine the proposed methodology for the estimation of IEEL proposed in Chapter 7 and to investigate the influence of age of broilers and the dietary cellulose contents on IEEL estimates. It was found that the age of broilers had no impact on the IEEL estimates. The IEEL was affected by the cellulose content and the IEEL increased from 0.37 MJ/kg DMI for the diet without cellulose to 1.80 MJ/kg DMI for the diet with 75 g/kg inclusion of cellulose. The findings reported in the current thesis demonstrate that the application of AMEn values determined based on assays using mash diets might result in over- or under-estimation of the available energy content of ingredients in commercial pelleted broiler diets and highlights the need for the use of pelleted diets in energy evaluation assays. The findings also revealed that the effects of age and methodology are relevant in the determination of AMEn of feed ingredients and question the validity of using single AME or AMEn values for feed ingredients in broiler diet formulations across different ages. Another notable contribution was to develop a novel approach to quantify the IEEL in broiler chickens for the first time. The thesis research also provides preliminary data on the TIDE of common cereal grains and highlights the possibility of applying the TIDE as an alternative to the ME system in poultry feed formulation.
  • Thumbnail Image
    Item
    Investigations into the impact of feed form and age on the standardised ileal amino acid digestibility of feed ingredients for broiler chickens : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science (Poultry Nutrition) at Massey University, Palmerston North, Manawatu, New Zealand
    (Massey University, 2022) Barua, Mukti
    The importance of measurement of standardised ileal digestibility coefficients (SIDC) of amino acids (AA) in feed ingredients and their value in improving inter alia the precision of broiler feed formulations needs no elaboration. Databases on the SIDC AA of ingredients are accumulating during the past decade and various factors that influence the digestibility have been identified. Two aspects that remain unexplored hitherto in detail are the effects of feed form (FF) and broiler age. Previous AA digestibility assays were accomplished using mash diets because of the simplicity and the fact that research facilities often do not have access to pelleting equipment. As commercial broilers are fed pelleted diets, the data derived from mash diet may not be directly applicable. Another limitation is that, despite the potential age effects on AA digestibility, no study to date has investigated the influence of age on the SIDC AA in ingredients for the whole growth period of broilers. Lack of age-appropriate basal endogenous AA (EAA) flow data for the correction of apparent ileal digestibility coefficients (AIDC) is another constraint. Most of the existing EAA flow data were generated using older birds (21 to 42 d of age). The focus of this thesis research was to address these critical aspects. The first two experimental studies in Chapters 3 and 4 were conducted to determine the effect of FF (mash vs. pellet) on the SIDC AA in four grains (maize, wheat, sorghum and barley) and three protein sources (PS; soybean meal; SBM, meat and bone meal; MBM, and CM; canola meal) in broilers, respectively. Regardless of the grain type, FF had no significant (P > 0.05) influence on the SIDC of any AA, except for Cys and Pro, which were higher (P < 0.05) in mash diets. The effect of FF was more pronounced in the SIDC AA of PS. No influence of FF (P > 0.05) was observed for the SIDC of individual indispensable AA (IAA), except for His, the digestibility of which was lower (P < 0.05) in the pelleted diets. The SIDC of all individual dispensable AA (DAA), average digestibility of DAA and total AA (TAA) were reduced (P < 0.05) by pelleting. Cysteine was the most affected DAA, with a 15.4% reduction in SIDC in pelleted diets in comparison with mash. These results showed that the use of SIDC AA data generated from feeding mash diets may overestimate the AA digestibility in feed ingredients and affect the precision of broiler feed formulations. For this reason, pelleted assay diets were used in succeeding trials. The third study, reported in Chapter 5, was carried out to investigate basal EAA flow at different ages (7, 14, 21, 28, 35 and 42 d post-hatch) of broilers, following feeding of a nitrogen-free diet (NFD). The basal EAA flow of all individual and total AA were reduced quadratically (P < 0.05 to 0.001) as the birds grew older. The EAA flows were higher on d 7, then declined on d 14 and plateaued until d 35. A further decrease in the EAA flow was observed on d 42. These age-specific values were used in the correction of AIDC to SIDC in all ensuing thesis studies. The study presented in Chapter 6 was conducted to determine the influence of age on the SIDC AA in two grain sources (wheat and sorghum) in broilers. Six broiler ages (d 7, 14, 21, 28, 35, and 42 post-hatch) were investigated. Two assay diets were formulated to contain 938 g/kg of each grain as the only source of AA. Each assay diet, in pelleted form, was offered to birds for 4 d during the six periods namely d 3-7, 10-14, 17-21, 24-28, 31-35 and 38-42 prior to ileal digesta collection. In the case of wheat, no age influence (P > 0.05) was observed on the SIDC of average of IAA and DAA, though the average of TAA tended (linear, P = 0.09) to increase with advancing broiler age. In sorghum, the average SIDC of IAA, DAA and TAA were higher (linear or quadratic; P < 0.05 to 0.01) at d 7, declined at d 14 and then evened out. Among the IAA, the SIDC of Arg, His, Ile, Leu, Lys, Thr, Val, and the SIDC of all individual DAA (with the exception of Cys) reduced with advancing age (linear or quadratic, P < 0.05 to 0.001). The study reported in Chapter 7 was conducted to measure the SIDC of AA in maize and barley at six ages (d 7, 14, 21, 28, 35, and 42 post-hatch). Two assay diets were formulated to contain 938 g/kg of either maize or barley as the sole source of dietary AA. In maize, the average SIDC of IAA and TAA was affected in a quadratic manner (P < 0.05) with the values being higher at d 7 that dropped at d 14, increased and evened out between d 21 and 35, and decreased again at d 42. A linear influence (P < 0.05) was observed in the average SIDC of DAA. The SIDC of average IAA, DAA and TAA in barley was influenced (quadratic; P < 0.001) by age. The digestibility values increased from d 7 to 21 and then plateaued until d 42. The SIDC of all AA in barley increased (quadratic; P < 0.05 to 0.001) as the birds grew older. The final study, presented in Chapter 8, was conducted to determine the influence of broiler age on the SIDC AA in two PS (SBM and CM). Six age groups (d 7, 14, 21, 28, 35, and 42) were utilised. Two assay diets were formulated to contain either SBM (413 g/kg) or CM (553 g/kg) as the only source of dietary AA. In SBM, the average SIDC of IAA and TAA were not affected (linear or quadratic; P > 0.05) by age. The average SIDC of DAA in SBM was affected in a quadratic manner (P < 0.05) and the highest value was observed at d 7, that followed by a decline from d 14 to 28, and increased beyond d 35. The average SIDC of DAA and TAA in CM were higher (quadratic; P < 0.05 to 0.001) from d 7 to 14, reduced at d 21 and then increased beyond d 28. The average SIDC of IAA dropped between d 7 and 28, and followed by an increase thereafter. The novelties of this thesis research are that (i) no previous study has investigated the SIDC AA of feed ingredients from hatch to the end of broiler growth cycle, (ii) this is the first study reporting age-appropriate basal EAA flows and (iii) the use of pelleted assay diets that resembled the FF commonly used in the broiler industry. There were several original findings in this thesis. First, pelleting had substantial impact on the SIDC AA of feed ingredients and FF influence was more evident in case of ingredients with higher protein contents. Second, the EAA flow was higher in younger birds and reduced with advancing broiler age. Third, the age effect on the SIDC AA was variable depending on the ingredient and specific AA, and that the age effect on AA digestibility need to be considered in ingredient matrices for precise feed formulation.  
  • Thumbnail Image
    Item
    Studies on the measurement of calcium digestibility in raw materials for poultry and of digestible calcium requirement of broiler starters : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science (Poultry Nutrition) at Massey University, Palmerston North, Manawatu, New Zealand
    (Massey University, 2021) David, Laura Shiromi
    The measurement of calcium (Ca) digestibility in feed ingredients for poultry is receiving increasing attention because of recent interest in formulating diets based on digestible phosphorous (P) and the close relationship between these two minerals in their absorption and post absorptive utilisation. Data on the ileal Ca digestibility of Ca sources and factors influencing Ca digestibility in poultry are scant. The current thesis presents follow-up studies of the previous work conducted at Massey University. The Ca digestibility values of Ca sources determined in the thesis, along with previous published data, were then used to develop dietary treatments to assess the digestible Ca requirement of broiler starters. The first study reported in Chapter 3 was conducted to examine the effect of basal diet composition on true ileal Ca digestibility of four Ca sources namely, limestone, meat and bone meal (MBM), monocalcium phosphate (MCP) and dicalcium phosphate (DCP) in broiler chickens. Two basal diets, namely a maize-based diet and a maize-starch-based purified diet, with each Ca source were tested. The results showed that the average true ileal Ca digestibility was higher in the maize-based diet (0.46) than that in the purified diet (0.37). True ileal Ca digestibility of limestone, MBM, MCP and DCP were determined to be 0.51, 0.41, 0.43 and 0.32, respectively. In the study reported in Chapter 4, the effect of dietary indicator-type and dietary adaptation length on the apparent ileal Ca digestibility of limestone were evaluated. In Experiment 1, the use of two indicators namely, titanium dioxide and acid insoluble ash (Celite) were compared and the findings showed that the ileal Ca digestibility was unaffected by dietary indicator. In Experiment 2, four dietary adaptation lengths namely, 24, 72, 120 and 168 hours were examined and it was found that the Ca digestibility was unchanged between 72 and 120 hours but decreased at 168 hours of adaptation length. The third study, presented in Chapter 5, was conducted to measure the influence of age (7, 14, 21, 28, 35 and 42 days post-hatch) on the Ca digestibility of limestone for broiler chickens. The findings revealed that the apparent ileal Ca digestibility coefficients were linearly decreased from day 7 to day 42. The ileal Ca digestibility coefficients were determined to be 0.51, 0.53, 0.36, 0.34, 0.41 and 0.27 at days 7, 14, 21, 28, 35 and 42, respectively. A secondary objective of this study was to examine the influence of dietary crude protein concentration (79 and 153 g/kg) on the apparent ileal Ca digestibility at 21 days of age. It was found the apparent ileal Ca digestibility was not influenced by dietary protein concentrations. The studies reported in Chapter 6 were conducted to measure the influence of phytase doses (0, 500 and 2000 FTU/kg) on the Ca and P digestibility of soybean meal (SBM) and canola meal (CM) in broiler starters (Experiment 1) and finishers (Experiment 2). True ileal Ca digestibility coefficients of SBM and CM, with no supplemental phytase, were determined to be 0.51 and 0.53, respectively, for broiler starters and 0.33 and 0.22, respectively, for broiler finishers. True ileal P digestibility coefficients of maize-SBM diet and maize-CM diet, with no phytase were determined to be 0.89 and 0.66, respectively, for broiler starters and 0.82 and 0.57, respectively, for broiler finishers. Microbial phytase increased the true ileal digestibility of Ca and P in maize-SBM diet and maize-CM diet, but the effect was more pronounced for the maize-CM diet. Superdosing of phytase (2000 FTU/kg) increased the Ca digestibility in CM and SBM by two-fold compared to the normal phytase dose (500 FTU/kg). The studies reported in Chapter 7 were conducted to determine the ileal Ca digestibility coefficients of two limestone sources in broilers and layers. The results showed that, in both sources, the apparent ileal Ca digestibility of limestone was found to be higher in laying hens (0.62 and 0.70) compared to broilers (0.50 and 0.43). The findings indicated that laying hens absorb Ca more efficiently than broilers which may be attributed to their high demand of Ca for eggshell formation. Using Ca digestibility values of Ca sources measured in this thesis work and previous published data, a growth study (Chapter 8) was conducted to estimate the standardised ileal digestible (SID) Ca requirement for 1 to 10 day-old broilers fed different dietary concentrations of both SID Ca (3.3, 3.9, 4.4, 5.0 and 5.5 g/kg) and SID P (4, 5 and 6 g/kg). Based on response surface models, the growth performance, bone mineralisation and mineral utilisation of broiler starters were found to be optimised at 5 g/kg SID P concentration. The concentrations of SID Ca that maximised body weight gain, tibia ash, tibia Ca, tibia P and toe ash were estimated to be 3.32, 4.51, 4.72, 4.36 and 4.78 g/kg, respectively, which corresponds to SID Ca to SID P ratios of 0.66, 0.90, 0.94, 0.87 and 0.96, respectively. Bone mineralisation required more SID Ca than for growth. Most of the findings reported in this thesis are novel and contribute to the advancement of current knowledge on the measurement of ileal Ca digestibility in poultry and the factors influencing Ca digestibility. The array of factors examined were hitherto unexplored and included the effects of basal diet type, dietary adaptation length, broiler age, phytase dose, Ca source and bird type (broilers vs. layers). Another notable contribution was to establish the requirements of digestible Ca, digestible P and the ratio of digestible Ca to digestible P for broiler starters (1-10-day old).
  • Thumbnail Image
    Item
    Influence of nutrient density and feed form on growth performance, nutrient digestibility and gastro intestinal tract development in broilers fed wheat-based diets : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Animal Science at Massey University, Manawatu, New Zealand
    (Massey University, 2019) Hamungalu, Obright
    This study investigated the influence of nutrient density and feed form, and their interaction on growth performance, nitrogen-corrected apparent metabolisable energy (AMEn) and upper gut components of broilers fed wheat-based diets for 35 d post-hatch. A completely randomised design was used, with a 5 x 2 factorial arrangement of 10 treatments (with 6 replicates, 8 birds per replicate) involving five dietary nutrient density, VL, very low nutrient density (11.71 MJ/kg AMEn, 13.44 g/kg lysine); L, low nutrient density (12.13 MJ/kg AMEn, 13.92 g/kg lysine); M, medium nutrient density (12.55 MJ/kg AMEn, 14.40 g/kg lysine); H, high nutrient density (12.97 MJ/kg AMEn, 14.88 g/kg lysine); VH, very high nutrient density (13.39 MJ/kg AMEn, 15.36 g/kg lysine) and two feed forms, mash vs. pellet. Nutrient density x feed form interaction was significant (P < 0.05) for weight gain and feed intake during finisher and whole grow-out period, while during starter period the interactive effect was significant (P < 0.05) for weight gain. At each nutrient density level, weight gain and feed intake were higher in birds fed pelleted diets than those fed mash diets, but the advantages of pelleting were greater at the lowest nutrient density. During whole trial period feed per unit gain (F/G) significantly (P < 0.001) improved as the nutrient density level increased, but it deteriorated (P < 0.05) due to pelleting. Effect of feed form was significant (P < 0.01) on bird uniformity, with pelleting having 10 % higher uniformity compared to mash diets. Increasing nutrient density had a significant (P < 0.001) effect on AMEn and coefficient of apparent ileal digestibility (CAID) of nitrogen (N), fat, Ca and P. There was a significant (P < 0.05) interaction between nutrient density and feed form for CAID of DM and GE. Pelleting reduced (P < 0.05) the CAID of DM and GE only in M and VH diets and did not have effect (P > 0.05) on these parameters in other nutrient density diets. Feeding pellets lowered (P < 0.05) the CAID of N and starch. Pelleting significantly (P < 0.001) reduced the absolute weight of gizzard compared to mash diets. The gizzard pH of birds fed pellet diet was higher (P < 0.001) than those fed mash diets. In general, the current results show that the pellet-induced benefits on growth performance reduce as the nutrient density levels increase, highlighting the importance of considering nutrient density to maximise the benefits associated with pellet feeding.
  • Thumbnail Image
    Item
    Persistent contamination of Salmonella, Campylobacter, Escherichia coli and Staphylococcus aureus at a broiler farm in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Microbiology at Massey University, Albany, New Zealand
    (Massey University, 2017) Castaneda, Kristine Mejia
    The public demand for poultry products has increased over the years due to their health benefits and relatively low cost. Intensive production of poultry in broiler farms gives an opportunity for contamination of the birds, thus creating potential foodborne hazards to consumers. Foodborne cases are therefore extensively monitored to implement mitigating strategies to control the outbreaks. Therefore, the main aim of this project was to determine the prevalence and microbial loads of contaminating Campylobacter spp., Salmonella spp., S. aureus and E. coli, in different locations of four broiler sheds at a selected poultry farm in Auckland New Zealand. Standard microbiological methods and multiplex quantitative polymerase chain reaction (qPCR) were used in the analyses. Swab samples were collected in three cycles from March 2016 to June 2016. During each cycle of the cleaning and disinfection regime, 248 swab samples were collected from feeders, feed loaders, drinkers, fans, vents, annex floor, and wall crevices to determine the extent of contamination before cleaning and after disinfection. The collected samples (n = 744) were analysed for the presence of Salmonella spp. and Campylobacter spp. using standard microbiological methods. Suspected isolates of Salmonella spp. were confirmed by latex agglutination test, whilst Campylobacter spp. was confirmed by both latex agglutination and oxidase tests. The swab samples were also analysed for viable S. aureus and E. coli cell counts using Petrifilm™ plates. Multiplex qPCR was developed and validated to enumerate Salmonella spp. and Campylobacter spp. positive samples. Results of this study showed that all collected samples were contaminated with Salmonella spp., Campylobacter spp., S. aureus and E. coli before performing cleaning. After disinfection, different areas of the shed were still contaminated, posing real danger for infection of the new flock. Crevices and drinkers were the most contaminated areas after disinfection. Organic matter that accumulates in crevices and drinkers during rearing are likely to protect pathogens against disinfectants, which may then contribute to residual contamination and biofilm formation. The ventilation system of the farm was also heavily contaminated. After disinfection, dusts were trapped between the wires of the ventilation screen, making air vents a potential source of contamination in poultry sheds. Feed loaders had higher contamination rates than feeders, even though it was elevated, away from direct contact to birds. When the ventilation system was open, contaminated dusts settle into various areas of the shed, thereby increasing contamination levels before cleaning, thus affecting the efficacy of the disinfectant used. Meanwhile, fans and the annex were less contaminated, indicating that the cleaning regime could effectively disinfect these areas. However, results showed that microbial concentration in the annex was higher after disinfection. This was probably caused by the introduction of pathogens from the outside environment, highlighting the importance of erecting hygiene barriers before entering the main shed. Multiplex qPCR is an important quantification tool due to its ability to detect, identify and quantify multiple pathogens in one assay. The standard curves generated from inoculated samples determined the detection limit to be 3.24 - 8.24 Log10 CFU/mL for Salmonella spp., and 2.97 - 7.97 Log10 CFU/mL for Campylobacter spp. respectively. The agreement of results using the standard and qPCR methods was investigated by comparing S. aureus counts obtained from100 environmental samples through Bland-Altman analysis. The two methods showed agreement, but the qPCR was limited to the detection of S. aureus from 3.5 to 6 Log10 CFU/mL. The concentration of Salmonella spp. and Campylobacter spp. enumerated by multiplex qPCR, had no significant difference between the mean counts of each location before cleaning and after disinfection. Concentration of Salmonella spp. and Campylobacter spp. in the samples subjected to analysis by qPCR post-disinfection, were below the detection limit of the method. However, the qPCR method may be suitable for analysis of samples collected before cleaning. Pre-enrichment of samples analysed post-disinfection is recommended to improve the detection and enumeration of Salmonella spp. and Campylobacter spp. by qPCR analysis.