Impact of glycine and serine supplementation on growth and nitrogen metabolism in broiler chickens with varying betaine supply
Résumé
Dietary glycine (Gly) is typically assessed alongside serine (Ser) at an equimolar level (Glyequi) due to their reversible metabolic conversion, which involves 1-carbon units (1C-units). However, Ser differs from Gly in the molar quantity of 1C-units it can produce, and Gly can also take up 1C-units. This study aimed to investigate whether the availability of excess 1C-units influences the utilisation of dietary Gly and Ser. Maize-soybean meal-based diets (15% CP) were formulated to contain 105% of essential amino acid concentrations recommended by the Gesellschaft für Ernährungsphysiologie (GfE, 1999). Experimental diets were supplemented with 0 or 2 g/kg betaine (Bet-, Bet+) as source of 1C-units. Diets were formulated to contain 10.0 g Glyequi/kg DM (no Gly or Ser supplementation (GlySer-)), 13.5 g Glyequi/kg DM (from either Gly (Gly+) or Ser (Ser+) supplementation), or 17 g Glyequi/kg DM (from either Gly (Gly++) or Ser (Ser++) supplementation), resulting in 10 experimental diets. 700 broilers were raised in floor pens and fed with a commercial starter. On d7, birds were allocated to 70 metabolism units, with 10 birds per unit. Each diet was tested in 7 replicates and fed from d7–21. Total excreta were collected twice daily on d18–21 to determine N-accretion and nitrogen utilization efficiency (NUE). Treatment effects were statistically analysed by one-way ANOVA. In Bet- treatments, Gly+ resulted in a greater increase in average daily gain (ADG d7-21) and average daily feed intake (ADFI d7-21) compared to Ser+ (P=0.017). In Bet+ treatments, ADG and ADFI remained similar, regardless of whether Gly or Ser was supplemented (P>0.050). Bet-Gly+ and Bet-Ser+ decreased feed conversion ratio (FCR) compared to Bet-GlySer- (P<0.001). In Bet+ treatments, where FCR was lower, only Gly++ and Ser++ reduced FCR compared to Bet+GlySer- (P<0.009). Gly supplementation increased N-accretion (d 18-21) in Bet- treatments compared to GlySer- and compared to Ser+(+) (P<0.001). In Bet+ treatments, neither Gly nor Ser supplementation led to an increase in N-accretion compared to Bet+GlySer- (P>0.050). In Bet- treatments, Ser++ had a lower NUE compared to GlySer- (P=0.046). Both levels of Gly and Ser+ maintained NUE at 77%, which was similar to the GlySer- treatment (P>0.050). In Bet+ treatments, neither Gly nor Ser supplementation affected NUE compared to the Bet+GlySer- treatment (P>0.050). NUE was lower for Bet+Gly+(+) and Bet+Ser+ compared to their Bet- counterparts (P≤0.048). In low crude protein Bet- diets, Gly supplementation appears necessary to counteract reduced growth and N-accretion and cannot be replaced by Ser supplementation. However, betaine supplementation appears to equalise the utilisation of Gly and Ser. Whether betaine supplementation contributed to the equimolar utilisation of Gly and Ser directly through its role as 1C-unit donor or via another mechanisms requires further elucidation. Reference GfE (Gesellschaft für Ernährungsphysiologie), 1999. Empfehlungen zur Energie- und Nährstoffversorgung der Legehennen und Masthühner (Broiler). DLG-Verlag, Frankfurt am Main, Germany
Domaines
![]()
Fait partie de 10.5281/zenodo.17035972 Article Metges, C., Kuhla, B., Hammon, H., & Daş, G. (2025). Book of Abstracts of the 8th EAAP International Symposium on Energy and Protein Metabolism and Nutrition (ISEP 2025). Research Institute for Farm Animal Biology (FBN), Dummerstorf, Germany. https://doi.org/10.5281/ZENODO.17035972