Dietary soluble non-starch polysaccharide level and xylanase influence the gastrointestinal environment and nutrient utilisation in laying hens
1. The objective of this study was to examine the influence of dietary soluble non-starch polysaccharide (sNSP) level and xylanase supplementation on productive performance, viscosity and pH along the gastrointestinal tract in laying hens. Excreta moisture content, ileal and caecal microbiota and short-chain fatty acid (SCFA) composition and apparent total tract nutrient utilisation were measured.
2. Hyline Brown laying hens (n = 144) were housed individually at 25 weeks of age and allocated to one of the four wheat-based dietary treatments in a 2 × 2 factorial arrangement, consisting of two levels of sNSP (High 13.40 g/kg or Low 11.22 g/kg), with or without xylanase (0 or 12,000 BXU/kg). Birds were fed the dietary treatments for 56 d.
3. Increasing dietary sNSP increased jejunum viscosity, degradability of total NSP, total tract flow of insoluble arabinose, and succinic acid concentration in the caeca (P < 0.05). Feeding high sNSP decreased excreta moisture content, total tract energy retention and free oligosaccharide, total tract flow of soluble and insoluble galactose and insoluble rhamnose and fucose, and ileal acetic and lactic acid concentrations (P < 0.05), and tended to reduce egg production (P = 0.058).
4. Supplementation with xylanase resulted in reduced jejunum and ileum viscosity, caecal pH, excreta moisture, flow of soluble arabinose and glucose and insoluble arabinose and xylose, caecal concentration of Lactobacillus sp. and isobutyric and succinic acid, and ileal concentration of Bacillus sp. and total anaerobic bacteria (P < 0.05). Xylanase application also increased energy retention and insoluble and total NSP degradation, and caecal abundance of Bifidobacteria sp. and valeric acid (P < 0.05).
5. These results reiterated the ability of xylanase to improve nutrient digestibility and reduce excreta moisture content in laying hens, and highlighted the importance of considering dietary sNSP level in laying hen diets.
The Effects of Different Sources and Levels of Trace Minerals on Poultry Performance and Gut Health
Trace minerals, zinc (Zn), copper (Cu) and manganese (Mn) have been well documented as essential components in the diets of poultry since they are involved in various physiological and biological processes within the body in maintaining bird health and performance. Different sources of trace minerals can differently influence growth rate and bird health. Three experiments were conducted to assess the effects of different sources and levels of trace minerals on growth performance and gut health of poultry.
The first experiment (shown in Chapters 3 and 4) evaluated the efficacy of different sources of zinc (Zn) (oxide and sulfate forms - ionic bound forms) versus zinc hydroxychloride (covalent bound form) (ZH) and incremental levels of ZH on growth performance and intestinal health of broilers fed wheat-soybean meal-based diets from d 0 to 35. The dietary treatments consisted of a positive control treatment (50 mg Zn/kg from Zn oxide and 50 mg Zn/kg from Zn sulfate), a negative control treatment (NC) which contained no supplemental Zn; the remaining 5 treatments contained Zn as ZH at 20, 40, 60, 80, 100 mg/kg. The findings obtained in this experiment showed that Zn supplemented from ZH was more efficacious than ionic bound forms in improving growth, feed efficiency, and breast meat yield. Despite the finding that feed intake was not different among treatments, the lower inclusion (40 mg/kg) of Zn as ZH resulted in similar body weight gain (BWG) to birds given a higher level of Zn as the ionic bound forms (100 mg/kg). The results also suggest that lack of Zn supplementation can negatively influence tibia development and gut microbiota composition in broilers. Higher supplemental Zn (80 mg/kg) in the diet alters the cecal microbiota population in favour of Lactobacillus and can decrease the total bacterial load. Supplemental Zn sources and levels in the feed have the potential to manipulate the jejunal gut integrity at a molecular level. The optimal requirement of Zn as ZH for broilers would be 100 mg/kg to meet all metabolic requirements of birds.
The second experiment (shown in Chapters 5 and 6) was designed to determine if nutritional (15 mg/kg) and pharmacological (200 mg/kg) levels of Cu hydroxychloride (CH) could effectively improve the growth performance and intestinal health of broilers, compared with Cu sulfate supplementation. The dietary treatments consisted of a negative control diet (NC) without any supplemental Cu, a basal diet supplemented with either 15 or 200 mg/kg Cu as CuSO4, and 5 diets supplemented with 15, 50, 100, 150, or 200 mg/kg supplemental Cu as CH. The results showed that the supplementation of Cu from CH was more efficient than Cu sulfate in promoting growth performance, both at nutritional and pharmacological levels. Birds fed 200 mg/kg Cu as CH gained more weight (77 g/bird) and had a lower FCR (3.2 points) compared to those fed 200 mg/kg Cu as Cu sulfate. This experiment demonstrated that the higher doses of Cu (up to 200 mg/kg) alter gut microbiota profile without compromising gut structural integrity or promoting tissue oxidation. Also, CH is more effective than Cu sulfate in making intestinal villi longer and reducing Cu excretion. Based on broken-line regression models, the optimal supplemental Cu as CH in the diet for the optimum body weight gain and FCR were estimated to be 109.5 and 72.3 mg/kg, respectively.
The third experiment (shown in Chapter 7) was designed to evaluate the effect of complete replacement of sulfate sources of Cu (15 mg/kg), Zn (80 mg/kg), and Mn (80 mg/kg) - (ITM) with hydroxychloride sources - (HTM) at the same inclusions on productive performance, egg quality, tissue mineralization and feed stability in Hy-Line Brown laying hens during post-peak production and under high ambient temperature. The results showed that HTM supplementation improved egg production, feed efficiency, eggshell quality, and egg mineral profile and produced darker brown eggshell color, although feed intake was not affected. These results are probably attributed to higher bioavailability of HTM compared with ITM in egg formation and pigment deposition into the eggshells, and in reducing the extent of oxidation in the feed, especially during high ambient temperature.
The results of these studies indicate that hydroxychloride trace minerals were more beneficial for broilers and layers over the ionic bound forms (sulfate, oxide) in improving growth performance parameters, intestinal health, productive production parameters, and egg quality of poultry. These effects may relate to the higher bioavailability, less reactivity with other minerals, greater oxidation stability of feed, and modulation of the negative effects of the high ambient temperature by trace minerals from hydroxychloride sources in poultry diets. The mechanism by which trace minerals as hydroxychloride contributed to lipid metabolism of broilers requires further research. An investigation into additional benefits of hydroxychloride trace mineral supplementation in post-peak laying hens could be of interest because commercial hens now lay for longer periods.
The effects of different sources and levels of trace minerals on poultry performance and gut health - Dataset
The dataset contains three raw data in excel files for three experiments outlined in the thesis. The data was collected during conducting the experiments and analysing chemicals in the lab. The data used in experiments 1 and 2 were collected at Animal House, The Centre for Animal Research and Teaching at The Unviersity of New England, Armidale, NSW. The data used in experiment 3 was collected at UNE SMART Farm at Teaching at The Unviersity of New England, Armidale, NSW.
Sources and levels of copper afect liver copper profle, intestinal morphology and cecal microbiota population of broiler chickens fed wheat‑soybean meal diets
Super dosing copper (Cu) has long been used as an alternative to antibiotic growth-promoters in broiler chickens' diet to improve gut health. This study was designed to compare nutritional and growth-promoting levels of Cu hydroxychloride (CH) with CuSO 4 on gut health bio-markers and liver mineral profile of broiler chickens. Ross 308 chicks (n = 864) were randomly assigned to eight treatments, as basal diet containing no supplemental Cu; the basal diet with 15 or 200 mg/kg Cu as CuSO 4 ; or 15, 50, 100, 150 or 200 mg/kg Cu from CH. The highest liver Cu content was observed in birds fed the diets with 200 mg/kg CuSO 4 (P < 0.01). Serum FITC-d concentration as the leaky gut marker, and liver malondialdehyde concentration were not affected. Copper level or source had no effect on cecal short chain fatty acid and the mRNA expression of five jejunal genes involved in gut integrity. Negative linear responses of Cu were observed on ,Lactobacillus (P = 0.032), Bacteroides (P = 0.033), and Enterobacteriaceae (P = 0.028) counts. The jejunal villus height increased in birds fed CH at 200 and 100 mg/kg (P < 0.05). Increasing Cu levels, linearly and quadratically (P < 0.001), increased Cu excretion.
Effect of Meat and Bone Meal, Phytase and Antibiotics on the Ash Content and Breaking Strength of Broiler Femurs, Tibia and Toe
Worldwide pressure to remove in-feed antibiotics from the poultry industry has resulted in heightened presence of the disease necrotic enteritis (NE) in broilers. Meat and bone meal (MBM) is readily used in broiler diets as a good source of protein, calcium and phosphorus, but it is also a predisposing factor for NE. A potential alternative to both antibiotics and MBM is the enzyme phytase, due to its ability to enhance nutrient digestion, particularly calcium and phosphorus. Enhancing mineral utilization and limiting nutrient availability for feeding pathogenic bacteria in the gut. The aim of this study was to use analysis of bone formation as a tool to assess the effects of phytase, MBM and antibiotics in broilers challenged with NE. Tibia and femur breaking strength and ash content and toe ash content was measured in NE challenged Ross 308 broilers (n=96) fed diets either with or without MBM, with or without antibiotic and either 500 or 1500 FTU/kg phytase, on d42 post-hatch. Results showed that MBM inclusion increased the tibia and femur ash content (P = 0.003 and P = 0.002, respectively) and breaking strength (P = 0.001). Toe ash content was highest in birds fed the low phytase level with antibiotic, as illustrated by a phytase x antibiotic interaction (P=0.031). Antibiotic had very little effect on bone ash content or strength. In conclusion, toe ash analysis suggests phytase has potential as a replacement for MBM, but further investigation is warranted into its ability to improve tibia and femur formation.
Abductive statistical methods improve the results of calibration curve bioassays: An example of determining zinc bioavailability in broiler chickens
In this paper, we discuss the theory behind calibration curve experiments and their application to a zinc (Zn) bioavailability study with broiler chickens. Seven replicates of 16 male commercial broiler chicks were fed starter diets for 14 days. Six diets had different levels of a potential Zn source and one was a positive control with standard industry levels of Zn for comparison. Four commonly used methods of calculating bioavailability means and confidence intervals (CI) from a calibration curve (standard curve) experiment to estimate the bioavailability of a new zinc source in broiler chickens were compared. The methods compared were the following: 1) the Counter-Intuitive Method uses a multiple-range test to compare unknown test and standard samples; 2) the Intuitive Method uses standard linear regression and inverts the equation to predict Zn bioavailability for each replicate of test samples; 3) the Abductive Method uses Graybill's Equation, based on theory and observation, to estimate CI's; and 4) the Sophistic Method uses reverse regression, and calculates Zn bioavailability values directly from the equation. The Counter-Intuitive Method only gives information about which standards the test samples are, or are not, significantly different from respectively (average available Zn not predicted). The Intuitive Method ignores error about the standard curve and theoretically cannot estimate the CI directly (X̄±SEM = 107.5 ± 15.8 mg Zn/kg). The Sophistic Method underestimates and overestimates the test sample mean values above and below the mean of the standards, respectively (X̄ = 96.6 mg Zn/kg). The Abductive Method has an advantage over the other methods: The mean prediction estimation is consistent with theory (107.5 ± 6.1 mg Zn/kg; X̄±SEM). When test or "unknown" samples are near the mean of the standard samples, the CI is smaller than when near the extremes of the calibration curve. When calibration curve error is small (R2 > approximately 0.95), there is little advantage to using the Abductive Method, but when calibration curve error is larger, as in many bioassays with growing animals, the Abductive Method improves the accuracy of the CI calculations. The Abductive Method was used to demonstrate the influence of the number of replicate samples on experimental power and cost.
Response to meat and bone meal, phytase and antibiotics on gut permeability, nutrient digestibility and caecal microflora in broiler chickens during a necrotic enteritis challenge
Necrotic enteritis (NE) is an enterotoxaemia of poultry with a significant economic effect on poultry production. Currently, antibiotics effectively prevent NE, but there is a global push for reduced reliance on the use of in-feed antibiotics (Castanon, 2007). Preventative treatments focus on the predisposing factors that instigate the disease. One such factor is meat and bone meal (MBM). The ingestible proteins in MBM (Kim, et al., 2012) cause production of toxic metabolites via proliferation of putrefying bacteria, such as highly proteolytic C. perfringens (Sharma, et al., 2017). Supplementing broiler diets with a 'superdose' of phytase has previously been shown to improve performance in NE challenged birds. The aim of this study was to investigate the effects of phytase in NE challenged birds fed MBM based diets, on gut permeability, nutrient digestibility and caecal microflora
Laying performance, egg quality and feed stability in response to replacement of inorganic zinc, copper and manganese with hydrixychloride sources in hy-line layer hen's diet
Traditionally, Zn, Cu and Mn have been added to poultry diets in the form of inorganic salts, such as sulphate, to meet requirements and prevent deficiencies. The sulphate sources of trace minerals have low bioavailability, are highly water soluble and reactive in the feed and digestive tract (Ma et al., 2011). Hydroxychloride minerals (HyC) are a class of naturally occurring minerals with fully defined crystalline structure, where the crystal is held together by a series of covalent bonds between the metal ion, multiple hydroxyl groups and the chloride ions. Compared to inorganic salts, HyC minerals have been found to be less water soluble, more bioavailable and exhibit less oxidant promoting activity in the feed (Perez et al., 2017).