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21.
Deficiencies of vitamins A, D, K, E and thiamin can cause severe limitations in beef production. In particular, vitamin A and E can be common causes of lost profit, secondary to limitations of reproductive and growth potential. Prolonged dry periods will reduce available A and E in pasture forage, as can ensiling and prolonged storage of harvested feedstuffs. Polioencephalomalacia is a thiamin responsive disorder, associated with high concentrate feeding and lush pastures. Antimetabolites, such as amprolium, will cause thiamine deficiency when fed in excess. Recent information has shown improved performance with supplemental beta carotene and niacin. The positive responses in reproductive performance, noted with cattle fed supplemental beta carotene, was independent of vitamin A. Supplementation of vitamins above National Research Council recommendations can be justified. However, proper evaluation of feed and animal status, and documentation of a response to supplementation is necessary before diagnosing deficiencies of specific nutrients.  相似文献   
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The activity of rat liver glutathione-insulin transhydrogenase (GIT) was measured by HPLC. The degradation of fluorescein isothiocyanate-I (FITC-I)-labeled insulin is separated into several peaks, which are bound different amount of FITC-I. We selected mono-fluorescein-thiocarbamylated insulin to estimate the decrease of insulin content and it became possible to assay GIT activity. This novel method was time-saving and simple, and this system could utilize instead of previous method.  相似文献   
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The effects of lipopolysaccharide ( Escherichia coli , O55:B5), administered 18 h after ovulation in the second oestrus after weaning on the hormonal profiles in 14 Swedish cross-bred (Landrace × Yorkshire) multiparous sows were studied. The endotoxin group (E-group) sows were administered with 300 ng/kg of lipopolysaccharide (LPS) whereas the control group (C-group) sows were administered 5 ml of saline intravenously via an indwelling jugular cannula. Blood samples for hormonal analyses were collected from all sows until slaughter. In the E-group, progesterone, cortisol and prostaglandin F metabolite levels increased significantly (p < 0.05) following LPS compared with the C-group. It can be concluded from this study that apart from elevating cortisol and prostaglandin F metabolite, LPS also elevates progesterone levels.  相似文献   
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2 groups of 20 cocks each were selected at random from non-dwarf White Leghorn (28 weeks post-hatch) and dwarf Krishna-J (38 weeks post-hatch) genotypes. The treated groups comprised 10 White Leghorn and 10 Krishna-J cocks. The remaining birds served as controls. 8 weeks prior to furazolidone treatment, semen was collected from both control groups at regular 4-day intervals, for 4 weeks. Cocks of the treated groups of both genotypes were administered furazolidone (0.14 g/bird/day) for 7 consecutive days. Semen was collected from all cocks at regular 4-day intervals for 4 weeks. Semen from the cocks of the same group was pooled. The pooled ejaculate volume and sperm density did not differ significantly in the 2 genotypes. The semen output as well as sperm density increased along with progressive attainment of sexual maturity. Furazolidone treatment caused significant reduction in semen volume as well as sperm concentration in either genotype.  相似文献   
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Abstract. Experiments were started in 1967 to investigate the effects of soil mixing on fen peat soil. Peaty topsoil was mixed with mineral subsoil to a maximum depth of 80 cm at two sites, one with a clay subsoil, the other sand. Mixing was done on a commercial scale with a range of implements. After initial increases, yields of arable crops on both mixed soils were subsequently similar to those on unmixed soil. Residual herbicide activity was enhanced on mixed soils, and evidence of peat conservation was obtained at one site. The practice has not been taken up commercially because of the high capital cost of mixing and lack of serious problems which had been predicted following peat wastage.  相似文献   
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