Exploratory on-farm study on animal welfare indicators and performance parameters in laying hens fed with and without soybean meal

In this exploratory field study, the effect of a soy-free laying hen diet on animal welfare indicators and performance parameters over the entire laying period (Week of Life (WoL) 18–78) were evaluated. The study included two flocks of 17,500 Lohmann Brown-Lite layers each. One flock was fed a diet containing a reduced content of soybean meal (SBM) (5%) and served as the control group (CoGr). The other flock was fed a soy-free diet containing sunflower meal, rapeseed meal, rapeseed expeller and maize dried distillers grains with solubles as substitutes for SBM (SfGr). There were minor effects on egg weight, the number of cumulated eggs and feed conversion ratio whereby CoGr showed slightly better results. Feed intake, laying performance and mortality were at the same level, whereby the laying performance of CoGr was slightly higher and the cumulative mortality slightly lower than that of SfGr during the laying period. Performance parameters were only analysed descriptively. In both groups, the plumage condition deteriorated from WoL 42 with CoGr consistently showing better plumage condition than SfGr. Significant differences were found in WoL 50 ( p = 0.025), WoL 59 ( p = 0.004), WoL 62 ( p = 0.031) and WoL 78 ( p <0.001) and over the entire laying period ( p <0.001). Furthermore, significant differences were found over the entire laying period with regard to footpad dermatitis ( p <0.001) and keel bone condition ( p = 0.030), with CoGr having better scores for footpad dermatitis and worse scores for keel bone condition than SfGr. No statistically significant differences were found in terms of body weight and integument condition. In general, the results should be interpreted with caution, as only one flock per diet with no replications was included in the study. Furthermore the diets were not isonitrogenous and not fully balanced in energy content and nutrient composition. Nevertheless, this study provides valuable insights into the possibility of eliminating soybean meal and using alternative protein sources in the feed for laying hens.