Genetic and phenotypic parameters for Aleutian disease tests and their correlations with pelt quality,reproductive performance,packed-cell volume,and harvest length in mink

Aleutian disease (AD), caused by the Aleutian mink disease virus (AMDV), is a major health concern that results in global economic losses to the mink industry. The unsatisfactory outcome of the culling strategy, immunoprophylaxis, and medical treatment in controlling AD have urged mink farmers to select AD resilient mink based on several detection tests, including enzyme-linked immunosorbent assay (ELISA), counterimmunoelectrophoresis (CIEP), and iodine agglutination test (IAT). However, the genetic analysis of these AD tests and their correlations with pelt quality, reproductive performance, packed-cell volume (PCV), and harvest length (HL) have not been investigated. In this study, data on 5,824 mink were used to estimate the genetic and phenotypic parameters of four AD tests, including two systems of ELISA, CIEP, and IAT, and their genetic and phenotypic correlations with two pelt quality, five female reproductive performance, PCV, and HL traits. Significances (P < 0.05) of fixed effects (sex, year, dam age, and color type), covariates (age at harvest and blood sampling), and random effects (additive genetic, permanent environmental, and maternal effects) were determined under univariate models using ASReml 4.1 software. The genetic and phenotypic parameters for all traits were estimated under bivariate models using ASReml 4.1 software. Estimated heritabilities (±SE) were 0.39 ± 0.06, 0.61 ± 0.07, 0.11 ± 0.07, and 0.26 ± 0.05 for AMDV antigen-based ELISA (ELISA-G), AMDV capsid protein-based ELISA, CIEP, and IAT, respectively. The ELISA-G also showed a moderate repeatability (0.58 ± 0.04) and had significant negative genetic correlations (±SE) with reproductive performance traits (from −0.41 ± 0.16 to −0.49 ± 0.12), PCV (−0.53 ± 0.09), and HL (−0.45 ± 0.16). These results indicated that ELISA-G had the potential to be applied as an indicator trait for genetic selection of AD resilient mink in AD endemic ranches and therefore help mink farmers to reduce the adverse effects caused by AD.     

Capability of some agricultural wastes for removing some heavy metals from polluted water stocked in combination with Nile tilapia,Oreochromis niloticus (L.)

Heavy metal (HM) pollution is one of the major problems that adversely affect the aquatic ecosystem and inhabiting biota. Heavy metals adsorption by low-cost adsorbents is one of the techniques used for HM removing from polluted water. In the present study, agricultural wastes (AW), i.e., rice straw, sugarcane bagasse, and maize stalks, were washed with distilled water, dried in a dry-oven, cut into small pieces (<0.5 cm long), and immersed at 1.0 g/L in aquaria containing synthetic mixture of lead (Pb), cadmium (Cd), copper (Cu), and zinc (Zn). Nile tilapia, Oreochromis niloticus (L.), fingerlings (25.2 ± 0.88 g) were stocked at a density of ten fish per 100-L aquarium for 72 h, during which fish were fed on a fish diet containing 25% crude protein ad libitum twice daily. Samples of water, AW, and fish were collected at different times to determine HM concentrations. The HM removal from polluted water was depending on the type of the metal ions, AW, and the contact time. However, HM concentrations in aquaria waters of all AW treatments decreased significantly by increasing contact time up to 24 h after which their concentrations were almost the same. Concentrations of waterborne Pb, Cd, Cu, and Zn in AW-containing aquaria were significantly lower than those of AW-free aquaria. The presence of any AW reduced significantly HM concentrations. In AW-free aquaria, HM-exposed fish accumulated more HM in their body than those reared in AW-containing aquaria. The results of this experiment showed that all AW had the capability to remove HM levels from the polluted water and reduce their bioaccumulation in fish body. However, rice straw was the more efficient adsorbent for all metals.