Table 6.

Effect of added Cu and diet type on gut morphology and relative mRNA gene expression of intestinal fatty acid binding protein (iFABP), copper transporter protein-1 (CTR1), and glucagon-like peptide 1 (GLP-1R) in the proximal and distal small intestinal (SI) of finishing pigs¹

Added Cu,2 mg/kg:	0		150		SEM	Probability, P <
Diet type:	Corn-soy	By-product3	Corn-soy	By-product3		Cu × diet type	Cu	Diet type
Gut morphology, μm
Proximal SI
Villus height	290	277	277	274	9.3	0.625	0.376	0.369
Crypt depth	244	244	214	221	16.7	0.843	0.102	0.874
Villus:crypt ratio	1.25	1.17	1.38	1.27	0.105	0.892	0.253	0.367
Distal SI
Villus height	412	404	375	400	17.9	0.340	0.230	0.615
Crypt depth	227	223	202	212	7.6	0.330	0.017	0.683
Villus:crypt ratio	1.83	1.83	1.88	1.92	0.106	0.834	0.514	0.823
Relative mRNA gene expression4
Proximal SI
iFABP	0.289	0.360	0.316	0.325	0.072	0.442	0.870	0.741
CTR1	0.591	0.601	0.661	0.528	0.130	0.363	0.882	0.457
GLP-1R	0.800	0.802	1.364	0.957	0.420	0.623	0.391	0.685
Distal SI
iFABP	1.143	0.726	0.664	0.571	0.178	0.283	0.032	0.258
CTR1	1.189	0.995	1.028	1.151	0.198	0.713	0.813	0.634
GLP-1R	2.336	1.592	2.088	1.718	0.566	0.575	0.664	0.382

¹A total of 84 pigs (PIC 337 × 1050; initially 27.6 kg BW) were used in a 117-d experiment with 2 pigs per pen and 7 replications per treatment.

²Tri-basic copper chloride (Intellibond C; Micronutrients, Inc., Indianapolis, IN).

³Refers to a diet containing 30% distillers dried grains with solubles (DDGS) and 15% bakery meal.

⁴All values indicate relative expression of genes. Normalized expression (ΔCt) for each sample was determined using ribosomal protein L4 as an endogenous control gene. The average normalized expression of the pooled control sample was used as the calibrator to calculate relative gene expression. For each sample, relative expression was calculated as 2^−ΔΔCt, in which ΔΔCt represents ΔCt sample − ΔCt calibrator (Livak and Schmittgen, 2001).