The problem of 'wet litter', which occurs primarily in grow-out sheds for meat chickens (broilers), has been recognised for nearly a century. Nevertheless, it is an increasingly important problem in contemporary chicken-meat production as wet litter and associated conditions, especially footpad dermatitis, have developed into tangible welfare issues. This is only compounded by the market demand for chicken paws and compromised bird performance. This review considers the multidimensional causal factors of wet litter. While many causal factors can be listed it is evident that the critical ones could be described as micro-environmental factors and chief amongst them is proper management of drinking systems and adequate shed ventilation. Thus, this review focuses on these environmental factors and pays less attention to issues stemming from health and nutrition. Clearly, there are times when related avian health issues of coccidiosis and necrotic enteritis cannot be overlooked and the development of efficacious vaccines for the latter disease would be advantageous. Presently, the inclusion of phytate-degrading enzymes in meat chicken diets is routine and, therefore, the implication that exogenous phytases may contribute to wet litter is given consideration. Opinion is somewhat divided as how best to counter the problem of wet litter as some see education and extension as being more beneficial than furthering research efforts. However, it may prove instructive to assess the practice of whole grain feeding in relation to litter quality and the incidence of footpad dermatitis. Additional research could investigate the relationships between dietary concentrations of key minerals and the application of exogenous enzymes with litter quality.

The crude protein (CP) content of 4 iso-energetic, maize-based diets containing 11.00 g/kg digestible lysine was reduced in gradations from 200 to 156 g/kg with increasing inclusions of synthetic, or unbound, essential amino acids. A constant dietary electrolyte balance (DEB) of 230 mEq/kg was maintained, but a second 156 g/kg CP diet had a DEB of 120 mEq/kg, and energy densities of the 156 g/kg CP diet were reduced in the sixth and seventh treatments. Each of the 7 dietary treatments were offered to 7 replicate cages (6 birds/cage) or a total of 294 Ross 308 off-sex male broilers from 14 to 35 D posthatch. Reductions in CP from 200 to 156 g/kg did not influence weight gain but quadratically increased feed conversion ratio (FCR) and linearly increased relative abdominal fat-pad weights and feed intakes. The reduction in DEB did not influence growth performance but did adversely influence some amino acid digestibilities. Reducing energy density by 100 kcal/kg did not influence growth performance of birds offered the 156 g/kg CP diet but numerically reduced fat-pad weights. The transition from 200 to 156 g/kg CP diets generally enhanced jejunal and ileal amino acid digestibility coefficients but had diverse effects on free amino acid concentrations in systemic plasma with a remarkable 116% increase in threonine. Starch:protein disappearance rate ratios linearly increased in the jejunum and the ileum following the same transition, and these expanding ratios were related to heavier fat-pads and compromised FCR. This study indicates that reductions in dietary CP from 200 to 172 g/kg supported by inclusions of unbound essential amino acids do not compromise growth performance, but a further reduction to 156 g/kg CP significantly increased FCR. Both heavier relative fat-pad weights and inferior FCR were related to expanding starch:protein disappearance rate ratios, which suggests condensed dietary starch:protein ratios may advantage birds offered reduced CP diets.

A total of 294 male, off-sex Ross 308 chickens were offered 7 dietary treatments with crude protein (CP) contents of 210, 195, 180, and 165 g/kg. One

Broiler chickens grow rapidly, and their nutrient requirements change daily. However, broilers are fed three to five diet phases, meaning nutrients are under or oversupplied throughout production. Increasing diet phases improves production efficiency as there is less time in the production cycle that nutrients are in under or over-supply. Nevertheless, the process of administering four or more diets is costly and often impractical. New technologies are now available to blend feed to match the daily nutrient requirements of broilers. Thus, the aim of this review is to evaluate previous studies measuring the impact of increasing feed phases on nutrient utilisation and growth performance, and review recent studies taking this concept to the extreme; precision nutrition - feeding a new diet for each day of the production cycle. This review will also discuss how modern precision feeding technologies have been utilised and the potential that new technologies may bring to the poultry industry. The development of a precision nutrition regime which targets daily requirements by blending dietary components on farm is anticipated to improve the efficiency of production, reduce production cost and therefore improve sustainability of the industry. There is also potential for precision feeding technology along with precision nutrition strategies to deliver a plethora of other management and economic benefits. These include increased fluidity to cope with sudden environmental or market changes, and the ability to alter diets on a farm by farm level in a large, integrated operation. Thus, the future possibilities and practical implications for such technologies to generate a paradigm shift in feed formulation within the poultry industry to meet the rising demand for animal protein is also discussed.

Hyperspectral imaging (HSI) is an emerging rapid and non-destructive technology that has promising application within feed mills and processing plants in poultry and other intensive animal industries. HSI may be advantageous over near infrared spectroscopy (NIRS) as it scans entire samples, which enables compositional gradients and sample heterogenicity to be visualised and analysed. This study was a preliminary investigation to compare the performance of HSI with that of NIRS for quality measurements of ground samples of Australian wheat and to identify the most important spectral regions for predicting carbon (C) and nitrogen (N) concentrations. In total, 69 samples were scanned using an NIRS (400–2500 nm), and two HSI cameras operated in 400–1000 nm (VNIR) and 1000–2500 nm (SWIR) spectral regions. Partial least square regression (PLSR) models were used to correlate C and N concentrations of 63 calibration samples with their spectral reflectance, with 6 additional samples used for testing the models. The accuracy of the HSI predictions (full spectra) were similar or slightly higher than those of NIRS (NIRS ${\mathrm{R}}_{\mathrm{c}}^2$ for C = 0.90 and N = 0.96 vs. HSI ${\mathrm{R}}_{\mathrm{c}}^2$ for C (VNIR) = 0.97 and N (SWIR) = 0.97). The most important spectral region for C prediction identified using HSI reflectance was 400–550 nm with R² of 0.93 and RMSE of 0.17% in the calibration set and R² of 0.86, RMSE of 0.21% and ratio of performance to deviation (RPD) of 2.03 in the test set. The most important spectral regions for predicting N concentrations in the feed samples included 1451–1600 nm, 1901–2050 nm and 2051–2200 nm, providing prediction with R² ranging from 0.91 to 0.93, RMSE ranging from 0.06% to 0.07% in the calibration sets, R² from 0.96 to 0.99, RMSE of 0.06% and RPD from 3.47 to 3.92 in the test sets. The prediction accuracy of HSI and NIRS were comparable possibly due to the larger statistical population (larger number of pixels) that HSI provided, despite the fact that HSI had smaller spectral range compared with that of NIRS. In addition, HSI enabled visualising the variability of C and N in the samples. Therefore, HSI is advantageous compared to NIRS as it is a multifunctional tool that poses many potential applications in data collection and quality assurance within feed mills and poultry processing plants. The ability to more accurately measure and visualise the properties of feed ingredients has potential economic benefits and therefore additional investigation and development of HSI in this application is warranted.