Search

This study explored feeding recycled food waste-based diets for gut health, nutrient digestibility, bone morphology, and bone mineral level in laying hens. Hy-Line Brown laying hens (n = 150) were randomly allocated to three experimental treatments consisting of a commercial control diet, a recycled food waste-based diet, and a 50:50 blend of the control and food waste-based diets, with 50 replicates of a single bird per cage per treatment from 24 to 63 weeks of age. Egg production was recorded daily and feed intake was measured weekly. The gut pH, jejunal and ileal morphology, nutrient digestibility, bone morphology, and mineral composition were measured at 63 weeks of age. Hens on the food waste-based treatment had similar egg production but lower feed conversion ratio (FCR, 1.948 vs. 2.172 kg feed/kg egg, p < 0.001) and higher ileal pH (p < 0.001) and bone ash content (p < 0.001) compared to birds on the control treatment. Moreover, hens fed the food waste-based diets had higher ileal digestible energy (p < 0.001); ileal energy digestibility (p < 0.01); tibia S, Fe, Mn, and Zn levels (p < 0.05); and Mg, K, S, Mn, and Mo digestibility (p < 0.05) compared to hens fed the control diets. Hens offered the 50:50 blend diets had higher tibia P, Mg, and Mo levels (p < 0.05) and higher Ca digestibility (p < 0.05) compared to those fed the control diets. Thus, feeding recycled food waste-based diets is effective to improve laying performance, nutrient digestibility, and bone mineralization in laying hens. [ABSTRACT FROM AUTHOR]

Understanding the order of limiting amino acids (AA) in reduced-protein (RP) diets for laying hens will facilitate precise feed formulation and ensure that AA requirements are met cost-effectively. The order of the first three limiting AAs—lysine (Lys), methionine (Met), and threonine (Thr)—has been well established in RP laying hen diets. This study aimed to determine the priority order of eight additional limiting AAs (critically important AAs) when formulating wheat–sorghum-based RP diets for laying hens: tryptophan (Trp), valine (Val), isoleucine (Ile), arginine (Arg), leucine (Leu), histidine (His), phenylalanine (Phe), and glycineequivalent (Gly). A total of 330 Hy-Line Brown laying hens were randomly assigned to 11 dietary treatments (30 replicates of individual birds per treatment) from 20 to 39 weeks of age (WOA). Treatments were a standard-protein (17.24% CP) diet as the control (SP); a reduced-protein (15.00% CP) diet with sufficient levels of Lys, Met, and Thr but insufficient levels of the eight experimental essential AA (RP); a reduced-protein diet with sufficient levels of all essential AAs (RP-EAA); and eight subsequent dietary treatments of the RP-EAA diet with one of the experimental essential AAs removed: Trp (RP-EAA-Trp), Val (RP-EAA-Val), Ile (RP-EAA-Ile), Arg (RP-EAA-Arg), Leu (RP-EAA-Leu), His (RP-EAA-His), Phe (RP-EAA-Phe), and Gly (RP-EAA-Gly). Eggs were collected and weighed daily, and feed intake and feed conversion ratio (FCR) were calculated weekly. External and internal egg quality was measured at 29 and 39 WOA. Nutrient digestibility, serum uric acid concentration, caecal microbiota composition, and tibia parameters were measured at 40 WOA. Overall, hens fed the RP-EAA-Val, RP-EAA-Ile, and RP diets presented significantly lower egg mass compared to hens fed the SP, RP-EAA-His, and RP-EAA-Gly diets (p < 0.001). Hens fed the RP diet and RP-EAA-Val diet had a higher FCR compared to those offered the RP-EAA, RP-EAA-Leu, RP-EAA-Phe, and RP-EAA-Gly diets (p = 0.046). Lower protein intake and excretion were observed in hens offered the RP diets compared to hens fed the SP diet (p = 0.001 and 0.018, respectively). Based on the egg mass, Ile may be considered the fourth and Val the fifth limiting AA, after Lys, Met, and Thr, in laying hens fed wheat–sorghum-based RP diets during peak lay. However, if ranked based on FCR, Val may be considered the fourth limiting AA, followed by Trp, Ile, Arg, and His as the co-fifth limiting AAs. Leu, Phe, and Gly may be considered as non-essential AAs for laying hens fed RP diets. [ABSTRACT FROM AUTHOR]

Chickens have a high dietary Arg requirement compared to mammalians as they have an incomplete urea cycle and therefore cannot synthesise Arg. Arginine is important for protein synthesis and is also involved in immunity being converted to nitric oxide (NO) at the macrophage level. Nitric oxide is secreted as a free radical during an immune response and is toxic to bacteria, intracellular parasites and also has strong anti-viral and anti-cancer properties. Also, NO serves as a regulating factor for intestinal blood flow, integrity, secretion, and epithelial cell migration. As Arg is a limiting factor for NO synthesis, the increased availability of Arg following dietary supplementation of Arg and/or its metabolites could increase the NO production and subsequent immune status in birds. Such improvements on bird health may become useful for antibiotic growth promoter-free poultry production. The Arg requirement in birds has received special interest due to its large variation in different dietary conditions. Growing evidence suggests that increasing the dietary Arg level and Arg to Lys ratio above currently accepted levels may be necessary to maximise the productive potential of modern broiler strains due to the modulatory effect of Arg on energy and protein metabolism. Also, literature evidence has indicated that crystalline Arg, guanidinoacetic acid (GAA), and citrulline (Cit) can provide Arg activity in chicken diets and are all commercially available. Furthermore, the use of Cit could escape the degradation of enzyme arginase in the intestine and liver resulting in higher Arg levels in the bloodstream and NO production compared to Arg supplementation. The addition of GAA may also provide additional benefits on increasing creatine level and energy metabolism in broiler chickens compared to Arg. This paper will provide new insights into Arg and Arg-sparing effects of GAA and Cit in the broiler diets with a special focus on the supplementation of Arg in reduced protein diets. [ABSTRACT FROM AUTHOR]