Table 1.
Summary statistics for 12 data sets obtained from the fit of Gompertz and scaled intake regressions
| Gompertz regression3 | Scaled intake regression4 | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Species1 | Data set | Range in u2 | A, kg | B, /d | R 2 | B* | C, kg/d | C* | R 2 | α |
| Rat | One | 0.17:0.95 | 0.44 | 0.0245 | 0.996 | 0.0196 | 0.0230 | 41.9 | 0.898 | 2.88 |
| Two | 0.16:0.96 | 0.41 | 0.0365 | 0.997 | 0.0287 | 0.0197 | 37.8 | 0.931 | 3.35 | |
| Chicken | Layer | 0.03:0.96 | 2.2 | 0.0239 | 0.998 | 0.0296 | 0.136 | 76.5 | 0.955 | 1.95 |
| Broiler | 0.02:0.98 | 5.6 | 0.0267 | 0.990 | 0.0425 | 0.208 | 59.1 | 0.880 | 2.81 | |
| Turkey | Female | 0.008:0.80 | 15 | 0.0256 | 0.997 | 0.0532 | 0.408 | 56.5 | 0.963 | 2.95 |
| Male | 0.004:0.75 | 28 | 0.0212 | 0.997 | 0.0521 | 0.571 | 50.1 | 0.954 | 3.54 | |
| Dog | 0.09:0.90 | 55 | 0.0167 | 0.968 | 0.0493 | 1.08 | 57.9 | 0.951 | 2.88 | |
| Sheep | Female | 0.34:0.82 | 100 | 0.0108 | 0.998 | 0.0374 | 1.72 | 59.6 | 0.856 | 4.30 |
| Male | 0.25:0.79 | 130 | 0.00915 | 0.999 | 0.0341 | 2.00 | 57.3 | 0.938 | 4.66 | |
| Pig | 0.03:0.55 | 230 | 0.0126 | 0.999 | 0.0547 | |||||
| Cattle | One | 0.18:0.72 | 520 | 0.00457 | 1.000 | 0.0247 | 7.29 | 75.9 | 0.987 | 3.43 |
| Two | 0.13:0.75 | 750 | 0.00341 | 0.999 | 0.0204 | 6.04 | 48.1 | 0.981 | 5.65 | |
| Average | 0.0372 | 56.4 | ||||||||
| CV, % | 34.8 | 21.5 | ||||||||
1Data sources: on rats from Tables A-11 (set one) and A-12 (set two) in Appendix A of Parks (1982); on male chickens from Table A-36 (layer) and A-24 (broiler) in Appendix A of Parks (1982); on female and male turkeys from R. M. Gous (University of Kwazulu-Natal, Pietermaritzburg, South Africa, personal communication) as described by Gous et al. (2019); on the Great Dane dog breed from Table A-6 in Appendix A of Parks (1982); on female and male Suffolk sheep from a selected line as described by Lewis and Emmans (2010); on gilts from Table 20 of Shull (2013); on cattle after weaning from Table A-3 (set one) in Appendix A of Parks (1982) and Table 1 (set two) from Taylor et al. (1986).
2Degree of maturity.
3Linear regression of the Gompertz variable, G = −ln(−ln(W/A)), on time t (d), where W (kg) is liveweight at t, A is mature weight, B is a rate parameter, and B* = B.A0.27.
4Quadratic regression of scaled feed intake on the degree of maturity (equation 1), where C is the maximum feed intake, C* = C/A0.73, and α is the scaled parameter value form the fit of the regression (equation 2).