The Effects of Breed, Neonatal Age and Pregnancy on the Plasma Copper Status of Goats in Oman

摘要

There is a history of copper deficiency in grazing Omani livestock and the copper status of three economically important goat breeds, Jabal Akhdar (JA), Batina (B) and Dhofari (D) were therefore compared in October/November (cool season) and June (dry season) in a penned flock given a plentiful dietary supply of copper. In the cool season, 62 lactating does (5 JA, 12 B and 33 D), their 0–5-day-old kids (17 JA, 19 B and 22 D) and 25 dry does (17 JA, 5 B and 3 D) were blood sampled. In the dry season, the does sampled were either barren (15 JA, 16 B and 13 D) or pregnant (9 JA, 13 B and 33 D). The samples were analysed for total copper (TCu) and trichloroacetic acid (TCA)-soluble copper (TCA-sol Cu). There were no effects of breed on TCu or TCA-sol Cu in the cool season, the overall means being 0.75 (SE 0.049) and 0.59 (SE 0.052) mg/L. The mean TCu was low in kids at birth (0.59 mg/L) but had increased to 0.86 mg/L by 4 days of age (p<0.001); breed differences were found (p<0.002), the pooled values for JA, B and D being 0.77, 0.59 and 0.68 (SE 0.033–0.044) mg/L, respectively. By the dry season, the mean TCu had risen in barren does to 0.96 (0.045) mg/L but not in pregnant does (0.76 (0.047) mg/L; p<0.002) and breed differences had emerged, the mean for D being 20% lower than those for JA and B (p<0.05). The highest TCu values were found in the 7-month-old kids in June (1.17 (0.039) mg/L) but the breeds did not then differ. Some effects on TCA solubility were found but were considered unreliable. Breed effects may have been diminished by the generous supply of copper and early stage of lactation studied.