饲料转化率的控制

饲料转化率(Feed Conversion Ratio,FCR)是商品肉猪场生产性能的一个反映,采食量和增重则是FCR的完整组成部分,但是影响它们的因素很复杂。因此,一群猪的FCR值可能会大幅变动。在大多数现代养猪场,更详细地监测会影响FCR的因素并寻找改善它的方法可能是有道理的。     

Antibody and complement mediated lysis of felid herpesvirus 1 infected cells in vitro

The lysis of cells infected by felid herpesvirus 1 (FHV) by feline anti-FHV antibody and complement was demonstrated. Lytic activity was sensitive to dilution of both antibody and, especially, complement. It was first detected within 10 to 20 minutes, increased rapidly during the next 30 minutes of incubation and then rose more slowly in a linear manner. Using standard antibody and complement concentrations and assay duration, it was shown that FHV infected cells underwent significant (P less than 0.05) lysis from eight hours after infection in a system in which FHV-specific membrane antigen was first detected at three hours after infection and spread of FHV by the intracellular route began eight to nine hours after infection. The ability of antibody and complement to reduce FHV spread in this system was demonstrated by a significant (P less than 0.05) reduction in FHV plaque numbers, although the restriction of spread was not absolute. Chelation of divalent cations and heat inactivation of complement factor B revealed that the lytic system was dependent on factor B and Mg2+ but not Ca2+, suggesting involvement of the alternative pathway of complement activation.     

肉种鸡的营养管理

肉仔鸡对饲料的适应性比较强,原因之一就是肉仔鸡食欲极强,所以饲喂不同的日粮对胴体的影响不是太大. 而对肉种鸡的饲养来说,情况就完全不一样了,因为肉种鸡在管理中要限饲.要让肉种鸡的生产力达到最大,特别要关注营养成分的摄入量,对肉种鸡采用的限饲,这本身就是个很大的应激,所以说,肉种鸡对疾病以及逆境也很敏感.     

Immunological and feeding studies on antigens derived from the biting fly, Stomoxys calcitrans.

Pairs of rabbits were immunised with three antigenic preparations derived from Stomoxys calcitrans gut, abdominal section and whole flies. Immunoblotting studies demonstrated that a humoral response was mounted against eight antigens from the gut preparation and 12 each from the abdominal and whole fly preparations. In vitro feeding experiments showed higher mortality between Days 4 and 7 in the group of flies which had fed upon blood from rabbits inoculated with the gut derived antigen. This group also produced the lowest percentage of viable eggs (15.5%).     

Golden Shiner Notemigonus crysoleucas× Rudd Scardinius erythrophthalmus Hybrids: Gonad Histology and Spawning Trials

Hybrid fish were produced in ponds by crossing golden shiners × rudd ( Notemigonus crysoleucas × Scardinius erythrophthalmus ) and rudd × golden shiners. Histologically, testes from the hybrids contained spermatocytes that resembled those of the parental species, but no sperm were observed. Lack of sperm in hybrids could have been a seasonal effect. The ovaries of both types of hybrids contained variable numbers of morphologically normal, vitellogenic oocytes and numerous abnormal oocytes in the chromatin nucleolar stage. Abnormal oocytes were necrotic or had irregularly shaped nuclei and clumped chromatin. Many oocyte nests contained infiltrating macrophnges. Spawning trials with F₁ hybrids did not result in spawning behavior or production of F₂ generation fish. Colden shiner × rudd hybrids are of reduced fecundity, but sterility was not conclusively demonstrated.