1. Respiration calorimetry measurements were made over 4 d on normally-fed groups of 10 male or 10 female quail during three periods commencing at 12, 19 and 26 d of age. Carcass compositions were determined on groups of birds of each sex at 2 and 5 weeks of age. 2. Expressed per unit body weight, food and metabolisable energy (ME) intake and weight gain decreased between 2 and 3 weeks of age, but remained constant thereafter. 3. No differences were observed between sexes for any variable measured. Efficiency of utilisation of ME for energy retention was only 0.33. This was mainly because the majority of energy was retained as protein tissue. 4. Nitrogen (N) retention (g/d) increased with increasing dietary N intake but when expressed as a proportion of N intake, declined from 0.46 at 2 weeks to 0.33 at 4 weeks. Fat retention increased substantially during week 4. 5. Carcass analyses showed that fat, protein and ash were higher for quail at 5 weeks than at 2 weeks of age. At 5 weeks carcass fat was only 60 g/ kg.
Calorimetric measurements were made on groups of Japanese quail selected for increased body weight at either 20 or 35 days on either a high- or low-nutrient density diet. For the majority of biological parameters measured, the selected lines outperformed the unselected controls. Weight gain, metabolizable energy (ME) intake, food conversion efficiency, and energy retention were greater for the selected than for the control line. The major difference between the two groups was the higher mean food consumption of the selected lines. Quail selected at 35 days on the high nutrient density diet ate more food, gained more weight and retained more energy and body fat than those selected at the same age on the low nutrient density diet. Net availability of ME for growth was the same (0.69) for the selected and unselected lines; it was 0.66 for protein deposition and 0.83 for fat deposition. Maintenance energy requirement for eight quail was 1.2 MJ ME (kg wt)-1 day-1. Retention of dietary nitrogen was 0.61 of nitrogen intake. There was no difference between the lines in starvation heat production. However, birds fed ad libitum prior to starvation had a 12% higher heat production than those restricted to 70% of ad libitum feed.
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