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Sources and routes of administration of copper and vitamins A and D on metabolic status of these micronutrients in suckling piglets
It has been recently shown that placental and colostral transfer of copper and vitamins A and D from dams to neonates is limited in pig species (Matte et al., 2014, JAS 92-Suppl. 2:153). The present study aimed to determine the efficiency of neonatal supplementation strategies for these micronutrients in piglets. Within litter from 14 sows fed conventional diets, 5 groups of 2 newborn piglets were formed. In each group, piglets received a combination of micronutrient source and route of administration as follows: oral vitamin D3, retinol-acetate and CuSO4 (T1); oral 25-OH-D3, β-carotene and Cu-proteinate (T2); UVB light exposure (20 min, every second d during lactation), oral retinol-palmitate and Cu-gluconate (T3); intramuscular vitamin D3 and retinol-propionate and oral Cu-acetate (T4); oral saline (CTL). Oral or intramuscular provisions corresponded to 12 mg of copper and 70 and 12 MIU of vitamins A and D, respectively, partitioned between administrations at 2 (33%) and 8 d of age (67%). This design was repeated with 14 other sows fed extra daily supplements of 25-OH-D3 (4 MIU), β-carotene (24 MIU) and Cu-proteinate (45 mg) from 90 d of gestation to 21 d of lactation (weaning). Blood samples were collected on piglets at 2 and 8 d of age (before treatment administrations) and at weaning for plasma 25-OH-D3 determinations. At 23 d of age, 5 repetitions of a combination of sow and piglet factorial treatments (n=50 piglets) were sacrificed for copper and retinol determinations in liver. For vitamin D, plasma 25-OH-D3 was increased by extra supplementation to sows (15.1 vs 13.1 ng/mL, P<0.02, SE=0.6). Within piglet treatments, at 8 d of age, values were greater in T2 than CTL (24.3 vs 6.8 ng/mL) and intermediate for other treatments whereas, at 21 d of age, the response was in favor of T3 vs CTL (20.8 vs 9.1 ng/mL, interaction piglet treatment x age, P<0.01, SE=0.9). Sow treatments did not influence liver copper and retinol. Liver copper concentrations in supplemented piglet treatments were globally 38% greater than CTL (93.8 vs 68.1 µg/g, P<0.01, SE=8.0). For retinol, hepatic concentrations were 3 times greater with T1 than with CTL (321.5 vs 103.8 µg/g) and intermediate for the other treatments (piglet treatment effect, P<0.01, SE=20.5). Therefore, marked increases of copper and vitamins A and D statuses can be achieved by the oral route of supplementation or UVB light to neonatal piglets. Moreover, for oral vitamins A and D, sources also matter.
Keywords: vitamins, trace minerals, neonatal piglets