根据已报道的猪抗菌肽pr-39基因和看家基因β-肌动蛋白（β-actin）基因序列，分别设计pr-j9和β-actiin的引物，探讨了PcR体系中适宜的Mgcl2浓度、循环次数，以及2对引物间竞争情况。实验揭示，要保证半定量RT-PcR的可行性与可靠性，适宜的Mgcl，浓度为25mmol/L，循环次数为29；由于2对引物之间的杂交配对，两对引物需分别进行扩增。根据以上信息构建一优化的半定量RT-PcR法，以β-actin为内标，研究不同生长阶段猪抗菌肽pr-39基因表达的差异。结果显示，不同生长阶段猪pr-39基因表达有差异，从出生到断奶前pr-39表达量呈增加趋势，断奶时表达量下降，断奶后随日龄增加pr-39表达量再逐渐增加。

An experiment was conducted with meat ducks to determine if betaine could replace methionine in a methionine-deficient diet. In order to avoid the effects of betaine as a methyl-group donor or as an osmoprotectant or coccidiostat enhancer, sufficient amounts of methyl-donating compounds were added and clean conditions were used to reduce the coccidiosis challenge. A total of 576-day-old female meat ducks were fed one of four diets in a 2 (0 and 0.5g betaine/kg)

Rare earth elements (REE) have been shown to influence growth performance in animal production, especially in pigs. In the present study, the effect of oral administration of rare earth elements on growing rats was investigated. Pure LaCl3 or an REE mixture containing 38% of LaCl3, 52% of CeCl3, 3% of Pr Cl3 and 7% of chlorides of other REE were used at two different concentrations as supplements to the diets. Fifty male Wistar rats at 4 weeks of age were allotted to five experimental groups: a control group; a La-low group and a La-high group with 75 and 150 mg/kg LaCl3

This study was conducted to evaluate developmental gene expression of lactoferrin and effect of supplementary iron on gene expression of lactoferrin in mice mammary gland using semi-quantitative RT-PCR analysis. In experiment 1, total twelve female ICR ( Institute of Cancer Research ) mice of four groups, each group of three mice at day 1, 9, 17 and 25 of lactation were used to determine effect of different lactating stages on mRNA expression of lactoferrin. In experiment 2, six groups mice (total twenty-four female mice at day 12 after mating) feeding purified diets (without iron or supplement iron) were assigned to two treatments (control and treatment). The feeding experimental period lasted 35 days. During feeding experiment, six mice with three animals each group were chosen at day 1, 9, 17 and 25 of lactation to determine the effect of iron on lactoferrin mRNA expression of mice at different lactating stages. The current results of experiment 1 showed that lactoferrin mRNA had strong expression at day 1 of lactation, and decreased gradually at day 9 and day 17 of lactation and then increased again markedly at day 25 of lactation. These results implicated that the expression of lactoferrin in mammary gland at different lactating stages is consistent with the changes of lactoferrin concentrations in milk. Iron significantly increased lactoferrin mRNA expression at day 1 and day 25 of lactation. Iron also increased lactoferrin gene expression at day 9 and day 17 of lactation, but statistical result was not significant. These findings raised the possibility that iron supplementation may play a role in regulation of lactoferrin levels in vivo.