Frédérique Mocz

1. This study evaluated the validity, inter-assessor reliability and intra-assessor repeatability of three visual scoring systems for litter quality, one known as the Welfare Quality Assessment Protocol (c) and two complementary systems for friability and humidity developed by the ClassyFarm initiative. 2. In 6 rooms of an experimental barn, 2450 medium-growing broiler chickens were reared on coarse sawdust litter until they reached a body weight of 2.2 kg at 43 days of age, with a stocking density of 33 kg/m(2). 3. Sixty-six litter samples were analysed for litter moisture at two different time points during the broiler chickens' production cycle, and were visually scored using the three systems, two consecutive times, by 7 assessors to analyse their validity, inter-reliability and intra-repeatability according to the litter moisture level. 4. The three resulting scores were correlated with the litter moisture (p < 0.001) and correlations were stronger when the litter moisture was above 35%. Similarly, inter-assessor reliability and intra-assessor repeatability were better for all three scoring systems when litter moisture was above 35% than when it was below 35%. 5. The ClassyFarm Friability system was the most reliable regardless of litter moisture level. The ClassyFarm Humidity system was the least reliable and repeatable when the litter moisture was below 35%. The Welfare Quality scoring system lay between the two ClassyFarm systems considering inter-assessor reliability, but was as repeatable as the ClassyFarm Friability system.

The dust level is included in the animal welfare legislation of the European Union, implying assessment of dust levels during veterinary welfare inspections. This study aimed to develop a valid and feasible method for measuring dust levels in poultry barns. Dust levels were assessed in 11 layer barns using six methods: light scattering measurement, the dust sheet test with durations of 1 h and 2–3 h, respectively, visibility assessment, deposition assessment, and a tape test. As a reference, gravimetric measurements were obtained – a method known to be accurate but unsuitable for veterinary inspection. The dust sheet test 2–3 h showed the highest correlation with the reference method with the data points scattered closely around the regression line and the slope being highly significant (p = 0.00003). In addition, the dust sheet test 2–3 h had the highest adjusted R² (0.9192) and the lowest RMSE (0.3553), indicating a high capability of predicting the true concentration value of dust in layer barns. Thus, the dust sheet test with a test duration of 2–3 h is a valid method for assessing dust levels. A major challenge is the test duration as 2–3 h is longer than most veterinary inspections. Nevertheless, results showed that potentially, with some modifications to the scoring scale, the dust sheet test may be reduced to 1 h without losing validity.

In conventional rearing systems, fast-growing broiler chickens commonly experience welfare issues, such as contact dermatitis, walking difficulties or a lack of expression of species-specific behaviours. Enriching their environment may be a way to improve their welfare. The objective of this study was to evaluate the benefits of elevated platforms and straw bales on the welfare of fast-growing broiler chickens reared at two different stocking densities. A total of 14,994 Ross 308 broilers were housed in 12 pens according to 4 treatments: 31 kg/m² with or without enrichments and 41 kg/m² with or without enrichments. The broilers’ walking ability, footpad dermatitis (FPD), hock burns (HB), weight, mortality and litter quality were assessed. Stocking density had a negative effect on FPD and HB, whereas enrichments reduced the occurrence of FPD and HB at both densities. There was a positive enrichment effect and a negative density effect on body weight at 25 days and on walking ability, but no effect on the litter quality or mortality rate. These results confirm that an enriched environment improves animal welfare in confined chickens, regardless of the stocking density. Reducing stocking density clearly appears to be an important means of increasing animal welfare.