1. Age-related changes in egg production, oviposition sequence length and inter-sequence pause length were studied by analysis of oviposition records of 50 individually-caged broiler breeders from 24 to 62 weeks of age. 2. The 44 surviving hens exhibited a production profile characteristic of broiler breeders (184 eggs per hen), with a peak mean sequence length of 19 eggs at 32 weeks of age. Inter-sequence pause length was maximum (1.6 d) at 54 weeks of age. Overall, the hens averaged 48 sequences, with a mean sequence length of 4.1 d. 3. Most hens had a single characteristically long sequence about the time of peak egg production (average: 24.3 d). The term 'prime' is suggested to denote this sequence. 4. Sorting the hens into groups on the basis of total egg output (upper and lower 50% and upper and lower 25%) indicated that high producing hens (upper 50% and 25%) had a very long prime sequence early in lay, and had few inter-sequence pauses of greater than 1 d duration. The converse was true for low producers (lower 50% and 25%). 5. The length of the prime sequence may be a good indicator of reproductive efficiency of hens later in life.

We have gathered, from the nests of dinosaurs, and living and fossil birds, some evidence of the environment in which these creatures lived. However, our isotope determinations suggest it will be impossible to resolve the problem as to whether the dinosaurs were warm-or cold-blooded from the oxygen and carbon isotopes content of their shells.

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White Leghorn male 4-week-old chicks and adult roosters were used to determine the effect of age on the true metabolizable energy (TME) and nitrogen-corrected true metabolizable energy (TME,,) value of ground yellow corn, dehulled soybean meal, wheat shorts, high-glucosinolate rapeseed meal, and dehydrated alfalfa meal. The TME and TME n values of each ingredient were calculated from its gross energy value and the regression of energy voided as excreta on the weight of feed consumed. Variable intakes of corn and soybean meal were obtained with chicks by feeding different amounts of the feedstuffs and with roosters by varying the duration of the feeding period. Variable intakes of the other ingredients were obtained by the force feeding of the birds.The TME values of the feedstuffs in kcal/g of dry matter for chicks and roosters, respectively, were as follows: corn, 3.93 and 3.98; soybean meal, 3.24 and 3.11; wheat shorts, 3.12 and 3.07; rapeseed meal, 2.24 and 2.50; alfalfa meal, 1.22 and 1.38. The TME n values of the feedstuffs for chicks and roosters, respectively, were as follows: corn, 3.76 and 3.88; soybean meal, 2.85 and 2.87; wheat shorts, 2.92 and 2.94; rapeseed meal, 1.99 and 2.24;alfalfa meal, 1.14 and 1.28. The TME values of soybean meal and rapeseed meal for chicks were 104% (P<.05) and 90% (P<.05), respectively, of the values obtained with roosters. The TME n values of corn and rapeseed meal for chicks were 97% (P<.05) and 89% (P<.01), respectively, of the values for roosters. The TME and TME n values of the other feedstuffs were not affected (P>.05) by the age of the bird.It appears that, with the exception of high-glucosinolate rapeseed meal, TME values obtained with adult roosters can be used in the formulation of diets for young growing birds.

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