胚胎移植技术的应用及其发展

动物胚胎移植首次成功(Heape 1891)距今已近一百年了。在这期间,又有多种动物胚胎移植试验成功,技术也不断改进。但是,进展较大的还是近二十年间。1981年Betterid-ge总结了胚胎移植历史,列出了13种动物胚胎移植首次成功的时间和试验者[兔1891Heape;大鼠1933 Nicholas;绵羊1934Warwick等;山羊(自身重移植)1934Warwick等;小鼠1942 Fekete＆Lit-tle;奶牛(流产)1949 Umbaugh;山羊1949 Warwick＆Berry;奶牛1951Willett等;猪1951 Kvasnickii;奶牛     

Experimentally induced foot rot in feedlot cattle fed rations containing organic iodine (ethylenediamine dihydriodide) and urea.

Foot rot was experimentally induced in feedlot cattle with a mixed inoculum of Fusobacterium necrophorum (Sphaerophorus necrophus) and Bacteroides melaninogenicus. Both bacteria were isolated from the lesions. Isolates of F necrophorum from 2 of the lesions were serologically compared, using a passive hemagglutination test with the strain used to induce the lesions. These isolates were serologically similar but not identical, indicating antigenic change had occurred during animal passage. The addition of ethylenediamine dihydriodide or urea to the rations did not affect the frequency of experimentally induced foot rot.     

Quantitative morphology studies on the development of body mass and various muscle groups in intensively reared rabbits]

Development of body mass and the mass of thigh, back and loins musculature was examined at 4, 8, 10 and 12 weeks in 51 California hybrids and 49 New Zealand White hybrids. Body mass development was practically identical in these rabbits. Peak growth rate of the characteristics studied occurred at 2-3 months of age in the California hybrids, but at a variable time in the New Zealand White. Age was less important than body mass in the development of criteria of productivity.     

Anatomical studies into the ruminal mucosa of pygmy goats in relation to their age

The ruminal mucosa of 15 pygmy goats of different age (Z1 approximately 4-5 months, Z2 approximately 1 year, Z3 approximately 1.5-5 years) were studied gross-anatomically concerning their colour, clumping of papillae, fodder precipitations on the papillae, areas poor in papillae or devoid of them and the development of papillae. The density of papillae/cm2 in the 3 groups investigated was 79.4; 67.3; 58.0; the mean length of the papillae (mm) 1.75; 1.86; 2.96; the mean breadth of the papillae (mm) 1.3; 1.2; 2.0; the area of the ruminal mucosa (cm2) 799; 943; 1 195; the area of the ruminal pillars (cm2) 38; 41; 69; the number of the papillae/rumen 59,940; 58,022; 64,782; the total absorptive area (cm2) 3,802; 3,854; 11,268; the surface magnifying factor 4.0; 3.4; 8.4.     

Comparative biological features of a rat liver abscess model induced with three Fusobacterium necrophorum strains

Several biological features were compared in a rat liver abscess model, using intraportal inoculations with 3 bovine strains of Fusobacterium necrophorum which varied in virulence. Serum alanine aminotransferase activities were increased significantly (P less than 0.05) in rats inoculated with F necrophorum 2101 by postinoculation hours 6, 12, and 24. Thereafter, alanine aminotransferase values returned to base line for the remainder of the experiment. Also, rats inoculated with F necrophorum 2101 had a significantly greater (P less than 0.05) weight loss than did the control rats during the first 5 postinoculation days and developed leukocytosis characterized by a neutrophilia with a left shift. The duration of the bacteremia was related directly to the virulence of the F necrophorum strain. Fusobacterium necrophorum 2101, a biotype A which was the most virulent, induced the most persistent bacteremia; F necrophorum 2035, a biotype B which was the least virulent, produced the shortest bacteremia; and F necrophorum 2030, a biotype AB which was of intermediate virulence, led to bacteremia of intermediate duration. Plasma endotoxin was demonstrated intermittently during the first 24 hours, but did not correlate with the bacteremia.     

Breed differences in sheep with respect to the accumulation of copper in the liver

Male lambs of the pure breeds Texel, Flemish milk sheep, and Finnish landrace, and of the crossbreds Texel x Friesian milk sheep, Texel x Finnish landrace, Suffolk x Friesian milk sheep, and Finnish landrace x Ile de France were fed hay and concentrates, the latter differing only in the content of copper. At high (+/- 35 ppm) and at moderately low (+/- 10 ppm) copper levels in the concentrate, breed differences in the accumulation of copper in the liver were studied. Hepatic Cu-levels increased significantly in the case of the high Cu-fed animals, but great differences in the metabolism of excessive amounts of dietary Cu exist between the particular breeds and crossbreds. The Texel breed was most susceptible to an excess of dietary Cu and the Finnish landrace was the least susceptible breed, while the Flemish milk sheep and the crossbreds were intermediate. In blood serum, the enzyme activities of sorbitol dehydrogenase, lactate dehydrogenase, gamma-glutamyl transferase, and glutamic oxaloacetic transaminase were increased to a greater or less extent in the high Cu-fed animals, but the correlation with hepatic Cu-content was poor. For the most susceptible breeds, even a level of 10 ppm Cu in a ration with nearly equal amounts of hay and concentrate is insufficiently low for the prevention of Cu-accumulation in the liver.     

Histological studies into the ruminal mucosa of pygmy goats in relation to their age

Ruminal mucosae of 15 pygmy goats of different age (Z1 approximately 4-5 months, Z2 approximately 1 year, Z3 approximately 1.5-5 years) and sex were investigated histologically. The thickness of the Stratum corneum of the 3 experimental groups was in the Atrium ruminis 23.0, 23.0 and 29.1 microns, in the Recessus ruminis ventralis 22.8, 28.0 and 30.0 microns, that of the Stratum germinativum and Stratum granulosum in the Atrium ruminis 74.8, 78.4 and 82.3 microns and in the Recessus ruminis ventralis 87.4, 84.7 and 87.7 microns, that of the Corpus papillare in the Atrium ruminis 75.3, 75.2 and 74.4 and in the Recessus ruminis ventralis 85.0, 78.9 and 71.6 microns. The cell nuclear volumes of the basal and parabasal cells of papillae originating from the Atrium ruminis (a) and the Recessus ruminis ventralis (b) in the individual experimental groups were in case of a 103.2; 100.2 and 117.3 microns3 resp. in case of b 93.4; 96.4 and 119.7 microns3.