Search

An 8-week feeding trial was conducted to estimate the optimum dietary manganese (Mn) requirement for juvenile hybrid grouper, Epinephelus lanceolatus × E. fuscoguttatus. The basal diet was formulated to contain 520 g/kg crude protein from casein and fishmeal. Manganese methionine was added to the basal diet at 0 (control group), 2.5, 5, 10, 20 and 40 mg Mn/kg diet providing 7.48, 10.34, 13.76, 19.72, 31.00 and 53.91 mg Mn/kg diet, respectively. Each diet was randomly fed to triplicate groups of juveniles, and each tank was stocked with 20 fish (initial weight, 60.06 ± 0.68 g). The manganese content in rearing water was monitored and kept below 0.01 mg/L. Results showed that the weight gain ratio (WGR), protein efficiency ratio (PER), specific growth rate (SGR), Mn contents in whole body, liver and vertebra, and activities of hepatic Mn superoxide dismutase (Mn-SOD), total SOD (T-SOD) and glutathione peroxidase (GSH-PX) were significantly improved by dietary Mn supplementation (p

Replacing dietary fish oil with DHA-rich microalgae Schizochytrium sp. and EPA-rich microalgae Nannochloropsis sp. for olive flounder (Paralichthys olivaceus) was examined. Three experimental isonitrogenous and isolipidic diets with lipid source provided by 50% fish oil (F50S50), 50% (M50F25S25) and 100% microalgae raw material (M100) respectively were compared with a soybean oil (S100) diet as control. Triplicate groups of olive flounder juveniles (16.5 ± 0.91 g) were fed the experimental diets, and a group was fed the control diets for 8 weeks in a recirculation system. Results showed feed efficiency and growth performance were not significantly changed when fish oil (FO) was totally substituted by soybean oil (SO) or microalgae raw material (MRM). The whole-body composition, lipid content of liver and muscle, and lipid composition of plasma were not significantly influenced by the total substitution of FO by MRM. The polyunsaturated fatty acids (PUFA) content of muscle and liver declined in fish fed S100 diet, whereas it was not significantly reduced in fish fed M50F25S25 and M100 diets. The total substitution of FO by MRM not only maintained the levels of arachidonic acid, EPA or DHA but also increased n-3/n-6 ratio. In conclusion, MRM as the sole lipid source is sufficient to obtain good feed efficiency, growth performance and human health value in olive flounder juveniles.

Yaks are the most important grazing livestock for milk production on the Qinghai-Tibetan plateau because these animals are adapted to the high elevations and extremes of cold and can graze throughout the year. In the present study, 30 yaks were selected and the fatty acid (FA) profile of yak milk at different seasons and parities was investigated using gas chromatography. The concentrations of cis-9 C18:1, cis-11 C18:1, cis-9,trans-11 C18:2, and C18:3 n-3 in yak milk were higher in summer (25.26, 1.50, 1.46, and 0.33 g/100 g of total FA, respectively) than in winter (22.17, 0.77, 1.27, and 0.28 g/100 g of total FA, respectively). The contents of monounsaturated and polyunsaturated FA in milk fat of multiparous (parities 2 to 5) yaks (31.61 and 4.20 g/100 g of total FA, respectively) were higher than those in primiparous yaks (29.61 and 3.80 g/100 g of total FA, respectively). These results suggest (1) that the potential exists to improve the FA composition of yak milk by developing local supplement resources during the winter and (2) that multiparous yaks have a more favorable FA profile than primiparous yaks.