A comparison of the energy and nitrogen metabolism of fed ducklings and chickens

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Abstract
Energy measurements were made over 4 d [days] on groups of 3 ducklings (aged 5-22 day) and 3 broiler chickens (11-32 d) offered high- or low-energy diets. Food, metabolizable energy (ME) and water intakes were significantly higher for ducklings than for chickens. The ratio of water:food was 4.2:1 and 2.3:1 for ducklings and chickens, respectively. The food conversion ratio differed between diets, but not species. Performance was generally better for both species on the high-energy diet. Heat production, energy, fat and protein retentions were higher for ducklings than chickens, and ducklings retained 0.44 of their energy as fat compared with 0.37 for chickens. The ratio of protein (g) to fat (g) retention was 2.2:1 and 2.8:1 for ducklings and chickens, respectively. For ducklings, metabolizability of the high-energy diet declined from 0.774 to 0.747, and to a lesser extent of the low-energy diet, as they aged. There was no such decline for chickens. Net efficiency of utilization of ME for gain was 0.64 for ducklings, compared with 0.50 for chickens. Fractional retention of dietary nitrogen (N) was 0.62 for ducklings and 0.55 for chickens. Gaseous ammonia-N was 4.5 and 2.2%, respectively, of N retained. In a 2nd experiment, groups of ducklings were offered high- and low-protein diets from 12-22 d of age. Comparisons among 4 diets showed that food and energy intake was lower on the low-protein diet than on the other 3. Energy retention on the high-energy diet was greater (P < 0.05) than on the other 3 diets. A high-energy diet is important for ducklings and chickens for maximum biological performance during the first 4 wk of life.