Growth analysis of the domestic fowl II. Effect of plane of nutrition on carcass composition

Extract

1. Two sample cockerels from each plane of nutrition treatment were killed and dissected at 0, 4, 10, 15 and 24 weeks of age. Details of the dissection technique are given.

2. All organs and tissues were weighed both wet and oven-dried. The total dry-matter content of the birds increased from 21% at hatching to 32% at 24 weeks.

3. The chief age changes in the proportions of the major joints of the bird consist of a marked increase in relative mass of wing, and a lesser increase in the leg joints. The early maturing head and neck joints decrease in relative mass by approximately onehalf. There are no treatment differences in the gross proportions of the birds calculated on the basis of weights of the major joints.

4. The advantages and disadvantages of the various methods of presenting quantitative growth analysis data are discussed. Reasons are given for employing several different methods in this work.

5. The amount of fat in the carcasses analysed varies considerably between individual birds. There are no consistent age or treatment effects on the fat contents of the cockerels. The interpretation of McMeekan's dissection analysis data is discussed, and reasons are advanced for conducting future experiments of similar nature on the basis of a fatfree carcass. It is argued that adipose deposits should not be considered in the same category as body organs and tissues.