Microbial communities of poultry house dust, excreta and litter are partially representative of microbiota of chicken caecum and ileum

Traditional sampling methods for the study of poultry gut microbiota preclude longitudinal studies as they require euthanasia of birds for the collection of caecal and ileal contents. Some recent research has investigated alternative sampling methods to overcome this issue. The main goal of this study was to assess to what extent the microbial composition of non-invasive samples (excreta, litter and poultry dust) are representative of invasive samples (caecal and ileal contents). The microbiota of excreta, dust, litter, caecal and ileal contents (n = 110) was assessed using 16S ribosomal RNA gene amplicon sequencing. Of the operational taxonomic units (OTUs) detected in caecal contents, 99.7% were also detected in dust, 98.6% in litter and 100% in excreta. Of the OTUs detected in ileal contents, 99.8% were detected in dust, 99.3% in litter and 95.3% in excreta. Although the majority of the OTUs found in invasive samples were detected in non-invasive samples, the relative abundance of members of the microbial communities of these groups were different, as shown by beta diversity measures. Under the conditions of this study, correlation analysis showed that dust could be used as a proxy for ileal and caecal contents to detect the abundance of the phylum Firmicutes, and excreta as a proxy of caecal contents for the detection of Tenericutes. Similarly, litter could be used as a proxy for caecal contents to detect the abundance of Firmicutes and Tenericutes. However, none of the non-invasive samples could be used to infer the overall abundance of OTUs observed in invasive samples. In conclusion, non-invasive samples could be used to detect the presence and absence of the majority of the OTUs found in invasive samples, but could not accurately reflect the microbial community structure of invasive samples

Why do we need low protein diets?

Presentation and pape

Amino Acid Supplementation in Reduced Protein Diets and the Impacts on Meat-Chicken Performance, Metabolism, and Physiology

Five industry-relevant animal experiments were completed to investigate amino acid supplementation in reduced protein diets and the impacts on meat-chicken performance, metabolism, and physiology. Specifically, the role of the non-essential amino acid glycine in reduced protein wheat-based diets was investigated. This work was developed in response of increasing expenses and environmental impacts associated with current dietary crude protein levels in broiler diets, however, reducing the crude protein and supplementing all assumed essential nutrients typically results in impaired performance. The work completed in this thesis contributes to our understanding of broiler amino acid requirements in reduced protein wheatbased diets. The first experiment investigated the role of the non-essential amino acid, glycine, in broiler performance when fed reduced protein wheat-based diets. An industry-standard protein diet and three reduced protein diets with and without glycine supplementation were fed to Ross 308 cockerels. Glycine was supplemented to equal that in the standard protein diet at 0.712 and 0.648% in grower and finisher diets respectively. Performance, water intake, and amino acid digestibility were measured. Reducing crude protein reduced body weight gain by up to 18% and reduced water intake by 28%. However, supplementing glycine in reduced protein diets restored the impaired performance and increased water intake. Supplementing crystalline amino acids in reduced protein diets increased their respective apparent ileal digestibility, with the greatest difference in threonine digestibility increasing by up to 8.3 percentage points. When feeding reduced protein wheat-based diets, supplementing crystalline amino acids, including glycine, can maintain performance like that observed in standard protein diets. A second experiment was completed to determine if supplementing glycine precursors have the same effect on performance as glycine in reduced protein diets. Ross 308 cockerels were fed one of two protein levels; an industry-standard protein diet with meat and bone meal or a plant-based diet approximately 3% lower in crude protein. In the reduced protein diet, glycine, serine, and threonine were assigned a glycine equivalence and supplemented to match the glycine in the standard protein diet at 1.558 and 1.390% in grower and finisher diets respectively. Reducing the dietary protein by 3% reduced feed efficiency by 10-points, however, the supplementation of glycine or serine did not restore performance. Threonine supplementation further reduced body weight gain in reduced protein diets by 6.8%. Therefore, glycine did not appear to be limiting in the reduced protein diet investigated, however, using threonine to supplement glycine requirements exacerbated the performance reducing effects of reduced protein diets. A third experiment explored the effects of different crude protein diets and the supplementation of glycine precursors on the in vivo synthesis of glycine. To investigate this, a second glycine equivalence level was added to the reduced protein treatments described above at 1.8% giving a total of eight treatments. Using these treatments, the effects of reduced protein diets on glycine and uric acid metabolism was investigated. The in vivo conversion of serine and threonine to glycine was evident in the blood plasma, however, reducing dietary protein reduced blood serum uric acid. The expression of hepatic genes for enzymes associated with threonine degradation to glycine, glycine degradation, and uric acid-synthesis were downregulated in reduced protein diets. No effect of crude protein or supplementing different glycine precursors at differing levels was observed on the expression of the enzyme associated with the interconversion of glycine and serine. The supplementation of excess essential amino acids and non-specific nitrogen may not fulfil the non-essential amino acid requirements for efficient growth as the in vivo synthesis of non-essential amino acids is altered in reduced protein diets. A fourth experiment investigated the differences in performance when increasing both the essential and non-essential amino acid densities by 15% in reduced protein diets. Ross 308 cockerels were fed one of three protein levels; standard, reduced, or low protein, with one of three amino acid profiles using AMINOChick®2.0 (Evonik Animal Nutrition, 2016) software recommendations; 100% amino acids (100% AA), 115% essential amino acids (115% EAA), or 115% amino acids (115% AA). In this experiment, glycine was considered an essential amino acid and formulated to 1.6% glycine equivalence. Performance, nitrogen digestibility, and blood parameters were measured. No significant difference was observed between feeding 100% AA and 115% EAA treatments at each protein level in body weight gain. However, feeding 115% AA increased body weight gain in standard and low protein diets by up to 18.7%. Blood parameters indicated reduced uric acid synthesis in low crude protein diets, despite glycine supplementation. Feeding 115% AA in the standard and low protein treatments increased nitrogen digestibility compared to the other amino acid profiles. The results from this study indicate that non-essential amino acids play key roles in growth and development that cannot be overcome with extra essential amino acid supplementation. Finally, a fifth experiment assessed the efficacy of low protein diets and increasing amino acid densities by 15% on mitigating the effects of sub-clinical necrotic enteritis. To investigate this, the standard and low protein treatments and the 100% AA, 115% EAA, and 115% AA profiles of the previous experiment were used in birds either challenged or not with sub-clinical necrotic enteritis. Ross 308 cockerels were fed one of six dietary treatments across 12 replicates. Six replicates per treatment were challenged with sub-clinical necrotic enteritis using Eimeria spp. and Clostridium perfringens. Differences in bird performance between those fed the standard and low protein diets were not apparent in challenged birds. Feeding diets with 115% AA increased body weight gain after the challenge by 10.5%. As evident from the finisher body weight gain, regardless of amino acid profile, low protein diets delayed recovery. However, in standard protein diets, feeding 115% AA increased body weight gain by 16.7%. These results suggest reducing crude protein may not mitigate the effects of sub-clinical necrotic enteritis, however, increasing both essential and non-essential amino acids will assist with recovery. The work completed has been highly industry-relevant and has highlighted the complex relationships between amino acids and the effects they have on meat-chicken performance, metabolism, and physiology. The Australian chicken meat industry now has a dataset of Australian diets for assessment to consider implementing reduced protein diets to improve industry sustainability and access potential diet cost savings

Glycine Supplementation of Low Protein Diets in Broilers

Soybean meal and meat and bone meal are the primary protein meals used in poultry diets. The high cost of soybean meal and nutrient variability of meat and bone meal suggests the industry needs to reduce protein meal dependence. High dietary protein is also associated with high water consumption, having a negative impact on litter quality and bird health (Alleman and Leclercq, 1997). The poultry industry currently supplements diets with methionine, lysine and threonine to reduce some dependence on protein meals. There is evidence that the supplementation of glycine in poultry diets can improve performance in low protein diets (Dean et al., 2006). Glycine is involved in a diverse range of metabolic pathways, including synthesis of proteins and purines. Although glycine is categorized as a non-essential amino acid, it may become limiting under certain circumstances (Corzo et al., 2004)

In vitro versus in situ evaluation of xylan hydrolysis into xylo-oligosaccharides in broiler chicken gastrointestinal tract

Xylan hydrolysis into xylo-oligosaccharides (XOS) was evaluated both in the gizzard and ileum of broiler chickens, and by a 2-step in vitro digestion assay that simulated the pH, temperature and time period of the gastric and small intestine (SI) phases. Twelve dietary treatments with varying soluble and insoluble xylan levels, either with or without supplemental xylanase, were fed to broiler chickens (n=576) for the in situ analysis, and were exposed to the in vitro assay. Relatedness of the two methods was strong for determination of XOS production in all dietary treatments for X₅, X₄, X₃, X₂ and X₁, respectively, in both the gastric (r=0.980, 0.853, 0.894, 0.870 and 0.951) and small intestine phase (r=0.957, 0.923, 0.940, 0.970, 0.969) (

Black Soldier Fly larvae in broiler diets improve broiler performance and modulate the immune system

Non-conventional feed ingredients are receiving more interest in their ability to increase farming efficiency, sustainability and animal performance. The objective of this study was to determine the optimal rate of inclusion level of the full-fat black soldier fly larvae (BSFL) in broiler diets and to evaluate their impact on performance, nutrient digestibility, and the immune system (blood cells and intraepithelial lymphocytes). A total of 400 male day-old Ross 308 broilers were randomly assigned to 5 treatment groups with 8 replicates each. Five inclusion levels of full-fat BSFL were investigated across starter (0, 2.5%, 5%, 7.5% and 10%), grower and finisher diets (0, 5%, 10%, 15% and 20%). All diets were formulated based on digestible amino acid values according to the Aviagen (2016) recommendations. A polynomial regression at different degrees was performed to analyse broiler performance parameters (body weight, body weight gain, feed intake, and feed conversion ratio), nutrient digestibility, and blood cell count. Intraepithelial lymphocyte population data was analysed performing univariate linear regression. During the entire experimental period (from 2 to 42 d), BSFL inclusion levels decreased the feed conversion ratio by 10% in broilers that received 20% BSFL in their diets (P

Effect of Pasture and Feed Additives on Performance and Egg Quality in Ranging Laying Hens

Free-range egg production is rapidly growing in Australia with an estimated retail value market share of 48% (AECL, 2014). Laying hens exposed to pasture range may experience reduced performance, poor enteric health and increased mortality (Ruhnke et al., 2014). In addition, egg quality can also be affected, indicated by the increased number of damaged and misplaced eggs as well as decreased egg shell quality (Kijlstra et al., 2009). These effects may be related to excessive fiber digestion and reduced nutrient uptake. The addition of multi-enzymes or organic acids to free-range layer diets may improve the digestion of nutrients, thus increasing performance, gut health and egg quality. A study was conducted to investigate the effect of range types and feed additives on performance and egg quality of ranging laying hens