Most diets for weanling pigs contain highly digestible plant and animal proteins, but there is an increasing trend to include more fibrous co-products in diets for pigs due to reduced diet costs. However, feeding diets to nursery pigs with high concentration of dietary fiber may reduce nutrient digestibility, induce intestinal inflammation, and subsequently depress growth performance. Addition of 100 to 200 mg/kg of Cu from Cu hydroxychloride (IntelliBond C^II; Micronutrients USA LLC; Indianapolis, IN) to diets improves feed efficiency and reduces post weaning diarrhea in pigs. However, there are at this point no data to demonstrate the effect of Cu hydroxychloride on intestinal barrier integrity of pigs fed low-fiber or high-fiber diets, and it is not known if Cu hydroxychloride influences immune responses of pigs. Therefore, 2 experiments were conducted to test the hypothesis that inclusion of 150 mg/kg of Cu from Cu hydroxychloride reduces intestinal permeability and subsequently improves growth performance of pigs fed diets without or with high concentration of dietary fiber.

Experimental Design

Experiment 1: Intestinal Permeability

Thirty two pigs (13.5 ± 1.3 kg) were allotted to a 2 × 2 factorial arrangement with 2 types of diets (low-fiber or high-fiber) and 2 levels of Cu from Cu hydroxychloride (0 or 150 mg/kg; Table 1). Low-fiber diets were formulated based on corn and soybean meal, whereas high-fiber diets were formulated based on corn, soybean meal, wheat middlings, and distillers dried grains with solubles (DDGS). Pigs were adapted to diets for 5 d, followed by the oral administration of lactulose and mannitol on d 6. After administration, urine was collected during two 6-h periods. Urine samples were analyzed for lactulose and mannitol to calculate for lactulose:mannitol ratio based on the percent recovery basis of sugars, which is considered an index for intestinal permeability.

Experiment 2: Growth Performance and Blood Characteristics

One hundred twenty eight pigs (8.3 ± 1.3 kg) were allotted to the same dietary treatments as in Exp. 1. There were 4 pigs per pen and 8 replicate pens per diet. Diets were fed to pigs for 21 d. On d 7, d 14, and on d 21, blood samples were collected from 1 pig per pen and tumor necrosis factor-α, immunoglobulin G, interleukin-1 ß, interleukin-10, blood urea N (BUN), total protein, and albumin were analyzed.

Results

Experiment 1: Intestinal Permeability

Inclusion of DDGS and wheat middlings in diets increased (P < 0.05) the lactulose:mannitol ratio during the initial 6-h period (Table 1). However, no difference was observed in the lactulose:mannitol ratio between pigs fed low-fiber diets and pigs fed high-fiber diets in the second 6-h period. The level of dietary Cu did not affect urinary lactulose:mannitol ratios of pigs.

Experiment 2: Growth Performance and Blood Characteristics

Overall ADG and G:F were greater (P < 0.05) for pigs fed diets containing Cu hydroxychloride compared with pigs fed diets without Cu hydroxychloride (Table 2). The level of dietary fiber did not affect overall growth performance of pigs. However, BUN concentration tended to increase (P < 0.10), and a reduction (P < 0.05) in albumin and interleukin-10 concentrations on d 14 was observed for pigs fed high-fiber diets compared with pigs fed low-fiber diets (Table 3). Supplementation of Cu hydroxychloride to diets positively influenced (P < 0.05) BUN, albumin, and cytokine concentrations of pigs.

Key points

• Inclusion of DDGS and wheat middlings in diets increased intestinal permeability and negatively influenced concentrations of BUN, albumin, and interleukin-10 in pigs.
• Pigs from approximately 8 to 18 kg tolerated diets containing 20% DDGS and 10% wheat middlings without apparent negative effects on growth performance.
• Supplementation of Cu hydroxychloride to low-fiber or high-fiber diets improved growth performance of pigs and Cu hydroxychloride positively influenced BUN, albumin, and cytokine concentrations in pigs.

Table 1. Urinary lactulose:mannitol ratios (percent recovery basis) of pigs fed low fiber or high fiber diets containing 0 or 150 mg/kg Cu from Cu hydroxychloride¹

¹Data are least square means of 8 observations per treatment.

²Diets containing added Cu were fortified with 150 mg/kg of Cu from Cu hydroxychloride (IntelliBond C^II; Micronutrients USA; Indianapolis, IN).

Table 2. Growth performance for pigs fed low fiber or high fiber diets containing 0 or 150 mg/kg Cu from Cu hydroxychloride¹

¹Data are least square means of 8 observations (pen as the experimental unit; 4 pigs per pen) per treatment.

²Diets containing added Cu were fortified with 150 mg/kg of Cu from Cu hydroxychloride (IntelliBond C^II; Micronutrients USA LLC; Indianapolis, IN).

Table 3. Blood characteristics for pigs fed with low fiber or high fiber diets containing 0 or 150 mg/kg Cu from Cu hydroxychloride¹

¹Data are least square means of 8 observations (pen as the experimental unit; 4 pigs per pen) per treatment.

²Diets containing added Cu were fortified with 150 mg/kg of Cu from Cu hydroxychloride (IntelliBond C^II; Micronutrients USA; Indianapolis, IN).

³BUN = blood urea N.

 ⁴TNF-α = tumor necrosis factor-α; IgG = immunoglobulin G.