The lowest dose of a feed supplement called N-carbamylglutamate, or NCG, gave Huoyan geese the strongest growth results in a 30-week feeding experiment. Birds receiving 0.06% NCG had the highest body weight from six weeks onward, and their average daily gain was better during the key four-to-eight-week growth period.
The result points to a dose effect rather than a simple rule that more supplement is better. The study also tested 0.12% and 0.18% NCG, and the highest-dose group had lower body weight than the comparator groups after 22 weeks. Its feed intake was also lower late in the experiment.
The experiment involved 240 one-day-old female Huoyan geese. They were randomly assigned to four groups of 60 birds, with six replicates of ten birds in each treatment arm. One group received a basal diet without NCG, while the others received 0.06%, 0.12% or 0.18% NCG in the diet for 30 weeks.
Researchers followed growth over time and assessed average daily feed intake, average daily gain and feed-to-gain ratio. In plain terms, these measures describe how much feed birds consumed each day, how much weight they added each day and how much feed was needed for each unit of weight gained.
The underlying calculations were straightforward. Average daily feed intake was total feed consumed divided by the number of experimental days, while average daily gain was final body weight minus initial body weight, divided by those days. The feed-to-gain ratio divided total feed intake by total body-weight gain.
What the gut analysis can and cannot say
The study looked beyond growth. It evaluated whether NCG influenced body size, meat quality and intestinal structure. It also explored whether the community of microbes in the cecum was associated with meat-quality traits.
That microbiome analysis was narrower than the feeding experiment. Researchers compared the control birds with only the 0.06% NCG group, rather than profiling all three supplement doses. As a result, the study could not compare microbiome results across all three doses.
The distinction matters because a microbial association does not by itself explain why meat-quality traits differed. The microbiome findings were associations, not direct evidence that particular microbes caused those changes.
A candidate dose, not a broad recommendation
Taken together, the results identify 0.06% NCG as the leading dose under the conditions tested. The finding is specific to female Huoyan geese, the diets and setting used in the experiment, and its 30-week duration. It does not establish that the same dose would work in other goose breeds, in male birds or in other species.
The study therefore offers a clear growth signal, but not a complete explanation of it. More detailed comparisons of the higher doses would be needed to connect the growth pattern with changes in the cecal microbiota. For now, the strongest evidence is the direct growth comparison: the lowest tested NCG dose performed best on the reported body-weight and average-daily-gain measures.
Paper data and sources
Original title: Effects of dietary N-carbamylglutamate supplementation on growth performance, meat quality, and cecal microbiota in Huoyan geese
Authors: Lei S, Xu Y, Zhang Y et al.
Journal/Repository: Frontiers in veterinary science
Status: Peer-reviewed
First online: 2026-10-19
DOI: Not available
Original paper · Full text