Table 9.

Prediction equations for body fat, protein, and energy retention in piglets measured from days 3 to 25 in lactation: exp 2

Response, Y	n	Prediction equation1,2,3	Model fit4
			RMSE	R 2
Body fat retention, g/d	36	−1.94 ± 3.58 + 0.18 ± 0.01 × live weight gain, g/d	3.37	0.86
	32	−6.39 ± 4.36 + 0.046 ± 0.004 × milk intake, g/d	3.51	0.85
	29	−5.17 ± 3.99 + 0.26 ± 0.02 × milk DM intake, g/d	3.55	0.84
Body protein retention, g/d	38	−0.009 ± 0.022 + 0.16 ± 0.00009 × live weight gain, g/d	0.03	0.99
	28	−11.3 ± 7.20 + 2.27 ± 1.00 × milk protein, % + 0.038 ± 0.003 × milk intake, g/d	2.39	0.89
	31	−0.45 ± 2.33 + 0.22 ± 0.01 × milk DM intake, g/d	2.85	0.85
Body energy retention, kJ/d	36	−77.5 ± 142 + 10.9 ± 0.58 × live weight gain, g/d	133	0.93
	32	−265 ± 217 + 2.73 ± 0.21 × milk intake, g/d	183	0.88
	29	−230 ± 200 + 15.7 ± 1.19 × milk DM intake, g/d	187	0.87

¹The model was $Y=b_0+b_1{X}_1\dots +b_i{X}_i+e$, where regression coefficients, b_1–i, were given as least squared estimates ± standard error to X_1–i.

²Three prediction equations were given for each response variable. The first equation allows only the inclusion of live weight gain, the second allowed inclusion of milk intake and milk constituents, and the third equation allowed the inclusion of intake of milk nutrients. Significant predictors in the regression models were determined through backward elimination. All variables included in the equations were significant at a 0.05-level.

³The milk nutrient concentrations were the average concentrations based on milk samples collected on days 3, 10, 17, and 25 in lactation. The milk intake was measured by the deuterium dilution technique.

⁴The model fit was evaluated based on root mean square error (RMSE) and R². In models with more than one predictor variable, the adjusted R² was given.