Table 3.

Effect fish oil inclusion in low protein quality diets on growth performance of pigs after weaning

	Dietary treatment1						P-value2
Item	High	Low0	Low1.25	Low2.5	Low5	SEM3	Treatment	Linear	Quadratic
BW, kg
Day 0	5.24	5.44	5.04	5.18	5.36	0.15	–	–	–
Day 7	7.19b	6.86a	7.04ab	7.11ab	6.92a	0.07	0.007	0.766	0.007
Day 14	9.44b	8.95ab	9.27ab	9.18ab	8.80a	0.14	0.029	0.229	0.037
Day 21	11.83	11.76	11.89	11.84	11.46	0.33	0.616	0.252	0.346
Day 42	25.99	24.81	25.27	25.66	24.38	0.65	0.437	0.613	0.248
ADG, g
Phase I, day 0–7	107b	60a	85ab	95ab	68a	11	0.007	0.766	0.007
Phase II, day 7–21	353	357	350	336	328	29	0.475	0.124	0.776
Phase III, day 21–42	654	615	629	651	609	26	0.649	0.858	0.301
Overall, day 0–42	470	443	454	461	432	16	0.469	0.594	0.275
ADFI, g
Phase I, day 0–7	165b	129a	138ab	145ab	135a	19	0.040	0.773	0.086
Phase II, day 7–21	467	455	446	429	415	31	0.049	0.013	0.731
Phase III, day 21–42	1005	952	998	1009	956	32	0.573	0.910	0.175
Overall, day 0–42	682	646	666	668	635	32	0.494	0.598	0.259
G:F
Phase I, day 0–7	0.569b	0.398a	0.514ab	0.564ab	0.440ab	0.04	0.042	0.722	0.014
Phase II, day 7–21	0.748	0.773	0.763	0.761	0.770	0.02	0.883	0.985	0.618
Phase III, day 21–42	0.661	0.650	0.641	0.659	0.644	0.02	0.783	0.916	0.764
Overall, day 0–42	0.672	0.647	0.658	0.675	0.650	0.01	0.450	0.885	0.169
ATTD OM, %4	83.5	81.6	83.4	82.0	82.8	0.63	0.142	0.539	0.543

¹Dietary treatments: [1] positive control (High; contained multiple sources of proteins, including animal proteins and 5% corn oil), [2] negative control (Low0; contained soybean meal as the main protein source and 5% corn oil), or 1 of 3 Low diets supplemented with increasing levels of fish oil to replace corn oil: [3] 1.25% fish oil (Low1.25), [4] 2.5% fish oil (Low2.5), [5] 5% fish oil (Low5) fed in 2 phases (7 and 14 d, respectively). All pigs received common phase III diets thereafter for 3 wk. Each mean represents observations on 6 pens.

² P-values for the main effect of dietary treatment, and for the linear and quadratic contrasts of supplementing Low diets with increasing levels of fish oil.

³Maximum value of standard error of the means.

⁴Apparent total tract digestibility of organic matter during phase II (week 2 and 3 after weaning; 6 pens per treatment week); interaction between diet and week was not significant; therefore, main effect of diet only is presented; main effect of week P < 0.001 (ATTD OM = 80.4 and 84.9 ± 0.43% on week 1 and week 2 of feeding phase II diets, respectively).

^a,bValues with different letters within the same row differ (P < 0.05).