Veterinärmedizinische Wissenschaft und Technologie

Several experimental systems are available for inducing spermatogenesis outside the endogenous testis. These systems have been developed as tools for studying spermatogenesis and as an option for preserving genetic material obtained from males when sperm recovery is not possible. Two in vivo systems are available for this purpose: tissue grafting and cell transplantation. Ectopic grafting of immature testicular tissues into immunodeficient mouse hosts is a type of in vivo system that allows the immature testicular tissue from many types of animals to undergo complete spermatogenesis. The other in vivo system is germ cell transplantation into the recipient testis, which induces colonization of spermatogonial stem cells from many types of animals and allows the stem cells to differentiate into spermatozoa in some cases. Furthermore, 2 in vitro systems are available: tissue culture and 3-dimensional (3D) cell culture. The tissue culture system and the combination of tissue culture and germ cell transplantation system were developed recently; this made it possible to perform complete spermatogenesis by using mouse spermatogonial stem cells. Isolated immature mouse testicular cells can differentiate into spermatozoa when the 3D culture system is used. All these systems have advantages and disadvantages with respect to studying spermatogenesis and preserving fertility in many types of animals. Therefore, it is necessary to consider many factors that might affect the results of spermatogenesis in order to use these experimental systems appropriately. Herein, we have discussed the advantages and disadvantages of these systems, especially in connection with several factors that may affect spermatogenesis.

A milk ELISA test for Antibody (Ab) against Bovine Viral Diarrhea (BVD) virus was studied in a dairy herd with past diagnoses of calves dying from BVD and Persistently Infected (PI) cows, with culling of all known PI cows. Modified live BVD vaccine was administered to calves 3 months and 4 months old, all cows at dryoff 45 to 60 days before calving, and 15-21 days in milk (DIM). Cows were tested 1 month apart (247 and 258 cows, respectively) using a competitive ELISA for milk Ab binding to p80 BVD non-structural protein. Results are reported as % binding by a second Ab; higher second Ab binding means the milk had less anti-p80 BVD Ab. Cows with 90-100% binding in milk on both tests were classified as low Ab–interpreted as a cow with PI or vaccine failure. Milk handling method was significant; fresh milk mean 49% second Ab binding was higher than for milk preserved 3 other ways. In fresh milk, 15 cows had 90-98% binding on one test, but 14/15 were milking during both herd tests and were below 90% on the other tests. Stage of lactation significantly affected results; anti-BVD Ab was higher from 1-30 DIM and lower from 61-150 DIM than at other stages of lactation. Ear notches were sampled concurrently from all cows for BVD antigen capture ELISA testing. Neither the milk ELISA results (no cows > 90% second Ab binding on both milk tests) nor ear notch testing classified any cows as PI animals. The milk BVD test might be useful to the dairy industry as a practical and convenient test for screening herd replacements, especially when large numbers of lactating cows are purchased and mixed into different pens throughout a dairy herd.

Little work has been conducted on parasitic infestation of harvested wild game at game abattoirs in Namibia. The aim of this study was to assess parasitic contaminations that occur in two commonly harvested Namibia game species. We examined springbok (Antidorcas marsupialis) and gemsbok (Oryx gazelle) carcasses for parasite infestation and rectal contents from eviscerated gut for worm egg counts among other routine inspection protocols. A filarial worm, Skrjabinodera kuelzii was found in 104 out of 540 carcasses harvested from separate 3 farms and then submitted for cutting and deboning. These filarial worms were predominantly between the hindquarter muscles, pelvis region and sometimes in renal fat. As a precautionary measure, these carcasses were condemned whole or part depending on the level of infestation. The larvae and filarial worms were only found in springbok but not in gemsbok carcasses. Worm eggs of strongyle, Strongyloides papillosus, Toxocara spp, Trichuris spp and coccidia were found in variable numbers in both springbok and gemsbok faeces, indicating a potential risk of transmission to other susceptible species in the ecosystem. The unusual deep muscle contamination of springbok carcasses by S. kuelzii are significant findings which should be considered during routine meat inspection of harvested wildlife.