Koperbehoefte van groeiende varkens (BO-20-006-006, BO-08-011.01-015)

Inclusion of pharmacological levels of copper (150 to 250 mg Cu/kg) in diets of weaned pigs generally increases feed intake and daily gain. The majority of this copper is excreted in the manure, thus contributing to accumulation in soil, ground and surface waters. Therefore, this study was conducted to determine the influence of level and duration of a growth promoting Cu-supplement within EC legal limits of 170 mg/kg as allowed until 12 weeks of age. The experiment comprised 7 treatments with 10 replicate pens of 10 weaned pigs (26 d of age), equal numbers of males and females each, as experimental unit. Pigs of treatments 1 to 4 received diets with 15, 80, 120 and 160 mg Cu from CuSO₄ per kg during an experimental period of 8 weeks post weaning to determine the dose effect of Cu inclusion. Pigs of treatments 5 to 7 received the diet with 160 mg/kg added Cu during a period of 6, 4 and 2 weeks post weaning, respectively, and subsequently the diet with 15 mg/kg added Cu, to determine the effect of duration of the high Cu supplement. Feed intake per pen and individual BW were determined in 2-week periods and growth rate and gain:feed ratio (G/F) determined. Faecal consistency was determined twice a week as percentage of pigs with loose faeces. On Day 56 post weaning 2 pigs from 4 replicate pens of treatments 1, 2 and 4 were sacrificed and samples of blood and tissues from liver, kidneys, adrenal glands, and various segments of the small intestinal tract were collected to determine copper content and mRNA abundance of two members of the mammalian copper transporter family, CTR1 and CRT2, and the Cu-ATPases, ATP7A and ATP7B by quantitative PCR. Analysis of variance was used to determine treatment differences, including linear and quadratic effects of dietary Cu level (Treatments 1 to 4). Pig performance in 2-week periods and the full 8-week period responded linearly to incremental dietary Cu levels in treatments 1 to 4 (P0.05).

In conclusion these results suggest that a reduction in Cu supplementation of pig diets to 120 mg/kg during 8 weeks or in duration of supplementation of 160 mg Cu to 4 weeks is possible without substantial loss in performance compared to a supply of 160 mg/kg during an 8-week period. The effect on faecal consistency requires further attention. Molecular analyses of copper transporters are being conducted.