Near-Infrared (NIR) Spectroscopy as an Alternative for Predicting n-Alkane Concentration in Excreta of Laying Hens: NIR-Generated Data for Dietary Composition Estimation

N-alkanes offer a promising approach for assessing the nutritional contribution of external sources to the diets of laying hens in free-range production systems. However, traditional laboratory methods, involving extraction, purification and gas chromatographic analysis, are both economically burdensome and time-consuming. Near-infrared spectroscopy (NIRS) is emerging as a viable alternative, with varying degrees of accuracy depending on the chemical nature and concentration of the component of interest. In our research, we focus on the accuracy of NIRS in predicting the concentrations of n-alkanes (C25-C33) in excreta under simulated free-range conditions with two different diets: one containing a commercial feed with minimal n-alkane content and another containing 1% alfalfa on top of the commercial feed. Spectra processing and calibration were tailored for each n-alkane, with NIRS performance influenced by diet type. Notably, plant predictions using NIR-generated data were consistent with laboratory results, despite a slight tendency toward overestimation (3.40% using the NIRS-generated C25-C29-C33 combination versus 2.80% using laboratory analysis). This indicates the potential of NIRS as an efficient tool to assess n-alkanes in excreta of laying hens and, consequently, the nutritional contribution of the free-range environment, providing rapid and cost-effective results.

Quantitative and Qualitative Evaluation of Plant Intake in Laying Hens: n-Alkanes as Predictive Fecal Markers for Dietary Composition Assessment

The shift in animal welfare standards towards free-range housing for laying hens in the EU has raised questions about changes in dietary composition. Accurate assessment of outdoor plant material intake is crucial for effective feeding strategies. This study introduces an approach using n-alkanes as markers to determine plant intake in laying hens, involving n-alkane recovery rate assessment, discriminant analysis and linear equation-solving for both qualitative and quantitative assessment, respectively, considering systematic n-alkane combinations. Two diets: a standard commercial diet and a diet incorporating 1% alfalfa were tested. Chemical analyses showed an altered n-alkane profile due to alfalfa inclusion, resulting a recovery rates ranging from 30-44% depending on the n-alkane type and diet. Statistical analysis revealed significant differences in recovery rates among the different alkanes for the same diets and between the diets for the same alkane, together with an interaction between n-alkane carbon chain length and initial concentration in the diet. The method accurately predicted plant inclusion, with a slight overestimation (2.80%) using the combination C25-C29-C33. Accurate qualitative classification of the animals based on fecal n-alkanes profiles was observed. The study successfully demonstrated the utility of n-alkanes for estimating dietary composition, providing a non-invasive approach for future free-range studies.

Enzymes and/or combination of organic acid and essential oils supplementation in pasture-fed free-range laying hens increased the digestibility of nutrients and non-starch polysaccharides

Pasture intake can be a major challenge for free-ranging hens. This study was conducted to examine pasture digestion and to manage its negative effects. A total of 300 ISA Brown laying hens were used to investigate the effect of time on range (T) in short-term (6 wk) and long-term (12 wk) of 2 range types (R) (gravel vs. pasture) and dietary supplements (F) (T1 = xylanase; T2 = xylanase/beta-glucanase/pectinase/protease; T3 = xylanase/benzoic acid/essential oils) on crude protein, crude fiber, acid detergent fiber, neutral detergent fiber, non-starch polysaccharides (NSP), calcium and phosphorus digestibility, pH of the crop, and ileum digesta viscosity and morphology. Hens exposed to the range for 12 wk had lower (P < 0.05) digestibility of crude protein, insoluble rhamnose, ribose, and lower ileal pH compared to hens that ranged for 6 wk. Hens ranging on pasture had lower digestibility (P < 0.05) of crude protein, acid detergent fiber, neutral detergent fiber, insoluble arabinose, and insoluble xylose, but higher digestibility (P < 0.05) of insoluble mannose and glucose compared to hens that ranged on gravel. Hens fed T2 and T3 had higher digestibility (P < 0.05) of CP, acid detergent fiber, and neutral detergent fiber compared to hens fed T1. Hens fed T2 had higher digestibility (P < 0.05) of free oligosaccharide arabinose and xylose than those fed T1 or T3 diets. A significant interaction between T × R was detected for crude fiber digestibility and villus height. Digestibility of crude fiber was reduced and villus height was increased in hens ranged on pasture for 12 wk compared to 6 wk. An interaction between R × F was observed on phosphorus and soluble NSP digestibility (P < 0.05). Hens fed T2 and T3 diets had lower digestibility of phosphorus and NSP on gravel than on pasture. In conclusion, pasture consumption impaired the digestibility of nutrients. Supplementing free-range diets with a multi-enzyme or xylanase/benzoic acid/essential oil product reduced these negative effects and increased the ileal nutrient digestibility.

Demographics and practices of semi-intensive free-range farming systems in Australia with an outdoor stocking density of ≤1500 hens/hectare

Baseline information on demographics and practices on semi-intensive free-range egg farms with an outdoor stocking density of ≤1500 hens/hectare in Australia is presented. Free-range egg production is changing the structure of the egg industry in Australia and a broad variety and tiers of free-range systems have emerged due to lack of concrete legislative standards on outdoor stocking densities in the past. Information was extracted from a pre-existing online free-range poultry survey dataset, consisting of a total of 79 questions related to nutrition, pasture management, welfare and health, animal housing, environmental impact and economics. Forty-one free-range egg farms, with an outdoor stocking density of ≤1500 hens/hectare, were identified in the dataset from all major Australian states. Two types of semi-intensive free-range housing systems were documented: mobile (modified caravan/trailer) housing (56%), and fixed sheds (44%). Seventy-two percent of respondents reported >75% of the hens in the flock used the outdoor range. All respondents reported ingestion of range components by hens in the form of vegetation, insects, stones and grit. Up to 10% mortality was reported by 40% respondents with predation (34%), cannibalism (29%), heat stress (24%) and grass impaction (19.5%) as major causes. Biosecurity on farms was sub-optimal with 8 of the 10 actions implemented by <50% respondents. Customer demand, consumer sentiment and welfare were the major factors for farmers moving into free-range egg production. This study resulted in identification of current practices and key challenges on semi-intensive free-range egg farms. Applied research and communication of results to farmers is highly recommended to ensure optimum health and welfare of free-range laying hens and sustained egg production.