This study was conducted to examine whether Cu could exert its growth-promoting effect when injected, rather than being fed, and thus bypass the gastrointestinal tract. In two 18-d experiments, pigs were injected every 2 d with a Cu histidinate or histidine solution. Amounts of Cu injected were calculated to simulate varying absorption rates in pigs fed 250 ppm of dietary Cu. In Exp. 1, 44 pigs were randomly assigned to four groups of 11 pigs each. Pigs were injected with four levels of Cu histidinate (0, 5, 10, and 15% estimated apparent absorption coefficients based on calculated feed intake). Average daily gain responded quadratically (P < .05) to levels of Cu histidinate; maximum growth was seen in the 5% group. At d 6, serum mitogenic activity also exhibited a similar quadratic response (P < .05). In Exp. 2, estimated Cu absorptions of 0, 2, 4, 6, and 8% were tested. Forty-five pigs were randomly assigned to five groups of nine pigs each and injected as in Exp. 1. Both ADG and serum mitogenic activity displayed a quadratic response (P < .05); the maximum response was seen in the 4% group. Liver Cu content, superoxide dismutase activity, and serum Cu concentrations were linearly increased (P < .05) with increasing dosage of Cu in both Exp. 1 and 2. Also, brain Cu content linearly increased (P < .05) with increasing dosage of Cu in Exp. 1 and 2. Pituitary growth hormone mRNA concentrations in Exp. 2 were not significantly influenced by treatments. This study shows that Cu may stimulate growth when injected intravenously, thus bypassing the gastrointestinal tract. Therefore, a mode of action that does not involve antimicrobial activity should be considered.
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出版者
Elsevier B.V.
其它主题
Hemoglobins; Growth & development; Skeletal; Developmental; Organ size; Messenger; Growth hormone; Male; Administration & dosage; Muscle weight; Intravenous; Injections; Feed conversion; Growth promotion; Random allocation; Muscle development; Drug effects; Veterinary
语言
英语
类型
Journal Article; Text
2024-02-28
2026-02-03
MODS