A disparate trace element metabolism in zebu (Bos indicus) and crossbred (Bos indicus × Bos taurus) cattle in response to a copper-deficient diet.

Copper deficiency is a commonly diagnosed problem in cattle around the globe. In Jimma, Ethiopia, 8 zebu (Bos indicus) and 8 zebu ×: Holstein Friesian cross (Bos taurus ×: Bos indicus) heifers were used in an 11-wk study to investigate breed type differences and effects of Cu deficiency on concentrations of trace elements in plasma and edible tissues as well as mRNA expression of Cu-related genes. Heifers were fed a grass diet (6.4 ± 0.2 [SEM] mg Cu/kg DM) supplemented with 1 mg Mo/kg DM in wk 1 to 4 and 2 mg Mo/kg DM in wk 5 to 11, with blood samples collected every 2 wk and tissue collection postmortem. Plasma, liver, kidney, and semitendinosus and cardiac muscle were analyzed for Zn, Cu, Fe, Se, Mo, Co, and Mn. Expression of mRNA Cu-related genes was measured in aorta (lysyl oxidase [LOX]), liver (Cu transporting ß-polypeptide [Atp7b], Cu chaperone for superoxide dismutase [CCS], cytochrome c oxidase assembly homolog 17 [Cox17], Cu transporter 1 homolog [Ctr1], and superoxide dismutase 1 [Sod1]), and duodenum (diamine oxidase [DAO] and metallo-thionein-1A [Mt1a]) as well as the Se-related glutathione peroxidase 1 (Gpx1). Zebu cattle maintained initial plasma Cu concentrations just below the threshold value for deficiency, whereas crossbred cattle gradually became severely Cu deficient over time (P < 0.001). In contrast, plasma Zn and Co were greater in zebu cattle at the onset of the trial but became similar to crossbred cattle towards the end of the trial (P < 0.001). Liver Cu (P = 0.002) and Fe (P ≤ 0.001), kidney Se (P < 0.001), and kidney and cardiac muscle Co (P ≤ 0.001) concentrations were greater in zebu than in crossbred cattle. Increased hepatic mRNA expression of the Cu regulatory genes Atp7b, Ctr1 (P = 0.02), CCS (P = 0.03), and Cox17 (P = 0.009) and Cu-related Sod1 (P = 0.001) as well as the Se-related Gpx1 (P ≤ 0.001) were greater in zebu than in crossbred cattle. However, duodenal mRNA expression of DAO (P = 0.8) and Mt1a (P = 0.2) and aortic expression of LOX (P = 0.8) were not different. Both the differences in Cu status indices (plasma and liver concentrations) and hepatic mRNA expression of Cu regulatory genes point to the possibility of a more efficient use of dietary Cu in B. indicus as compared to B. taurus ×: B. indicus cattle resulting in greater sensitivity to Cu deficiency in B. taurus crossbred cattle.

Nutritional and physical characteristics of commercial hand-feeding formulas for parrots.

Hand-rearing is a common practice for the propagation of captive psittacines, however, research on their nutrition is limited and the requirements of growing chicks are not well understood. The nutrition of 15 commercially available parrot hand-feeding formulas was compared with the average content of the crops of free living Scarlet Macaw (Ara macao) chicks, as well as with the requirements of 6- to 12-week-old leghorn chickens. When the formulas were prepared for a 1-week-old chick, all except three maintained >90% of solids in suspension after 15 min and >60 after 30 min. On average the formulas had a similar metabolizable energy density as wild macaw crop samples. The concentration of crude protein in the formulas was higher than that of the crop sample average, while the crude fat was lower than the average crop samples. More than 50% of the formulas had concentrations of K, Mg, and Mn less than the crop sample average, and Ca and Na concentrations below the requirements established for 6- to 12-week-old leghorn chickens. For >45% of the formulas the concentrations of arginine, leucine, and methionine + cystine were below the requirements of 6- to 12-week leghorns. When commercial formulas were prepared according to the manufacturer's instructions, the different dilutions greatly magnified the nutritional differences among them. Overall, the inconsistency in the nutrient concentrations among the formulas suggests that there is no consensus among manufacturers of the correct nutrition for growing psittacines and the industry could benefit from continued research in this area.

Antioxidant status of faeces of captive black rhinoceros (Diceros bicornis) in relation to dietary tannin supplementation.

In context with the frequent observations of excessive iron (Fe) storage in captive black rhinoceroses (Diceros bicornis), it has been suggested that both an excessive dietary Fe content and a lack of dietary Fe-chelating substances, such as tannins, is the underlying cause. Therefore, studies on the effects of tannin supplementation to captive diet are warranted. Six captive rhinoceroses were fed their normal zoo diet (N), and a similar diet supplemented with either tannic acid (T, hydrolysable tannin) or quebracho (Q, condensed tannins), and the total antioxidant capacity (TAC) was measured as mmol Trolox equivalents per kg fresh faeces. The TAC values on diets N (1.24 +/- 0.39 mmol/kg fresh faeces) and T (1.34 +/- 0.33 mmol/kg fresh faeces) were similar, but significantly higher on diet Q (2.32 +/- 0.61 mmol/kg fresh faeces). In contrast to expectations, faecal TAC increased with increasing faecal Fe, possibly as a result of the fact that the faecal Fe content was positively correlated to the proportion of concentrate feeds in the diet, which also contain antioxidants, such as vitamin E, in addition to Fe. Increased antioxidant status caused by the use of tannin substances could have a beneficial effect on animal health, but if tannins should be incorporated in designed diets, other tannin sources, such as grape pomace should be tested.

Role of excessive maternal iron in the pathogenesis of congenital leukoencephalomalacia in captive black rhinoceroses (Diceros bicornis).

OBJECTIVE: To investigate the possibility that excessive maternal iron (overload) may contribute to development of congenital leukoencephalomalacia in captive black rhinoceroses. SAMPLE POPULATION: Tissue specimens and serum samples from 18 rhinoceroses in 2 kindreds harboring 4 (possibly 5) affected female calves. PROCEDURE: Fresh and archival sera and necropsy tissue specimens were evaluated to determine the nature and extent of iron overload in captive and wild black rhinoceroses as well as other rhinoceros species. RESULTS: Quantitative serum and tissue assays of iron and iron analytes, corroborated by histopathologic findings, indicated that these kindreds carried the greatest body burdens of iron yet found among captive black rhinoceroses. Fourteen of 18 rhinoceroses had the highest serum ferritin concentrations measured among 64 black rhinoceroses in captivity in the United States. Dams of affected calves had serum ferritin concentrations 2 orders of magnitude higher than clinically normal humans, equids, or free-ranging rhinoceroses. A neonatal serum sample from 1 affected female calf had a high ferritin concentration (approx 100-fold increase), but a male sibling of another affected female did not, suggesting a possible sex disparity in fetal response to maternal iron overload. Morphologic hallmarks of hemochromatosis were prominent in dams and grandams of affected calves. CONCLUSIONS AND CLINICAL RELEVANCE: Excessive maternal iron may affect female fetuses more than males, possibly inducing leukoencephalomalacia by catalyzing production of highly toxic hydroxyl free radicals during crucial periods of in utero development. Reduction of maternal iron overload may decrease the probability of developing leukoencephalomalacia and some other disorders commonly affecting rhinoceroses in captivity.