低排泄氮量的鹌鹑改良选育

选用日本鹌鹑N、B（Normal、Brown）品系和杂种群（BN），共进行8个世代（6～20周龄）的选育试验，各品系采用单因子试验设计，在CP18％日粮条件下分选育组、非选育组以及对照组（CP24％），N、B基础群中选留15种家系，以采食量为主选性状，以产蛋率和排泄氮量为辅选性状作为选育指标进行试验。结果表明：随着世代数的增加选育组和对照组的适应力均有显著升高（P〈0．05），N品系的各世代遗传改进量为0．26；另外，世代间产蛋率有增高的倾向，选育组平均累积产蛋率与非选育组较显著升高（P〈0．05），特别是选育组各世代遗传改良极为显著（P-〈0．01）。各世代间采食量无显著差异，同世代各品系间选育组N、B采食量均高于非选育组，但显著低于对照组（P〈0．05）。选育组排泄氮量和血清中尿酸含量在改良2世代后明显低于非选育组和对照组（P〈O．05），排泄氮量分别降低7％～15％。综上所述，通过选育N、B新品系，能够改善产蛋性能，且显著降低排泄氮量，在BN杂种群中效果更明显。

低蛋白日粮选育对鹌鹑氮代谢和血清尿酸浓度的影响

试验选用日本鹌鹑N(Normal)、B(Brown)品系和杂种群(BN),共进行8个世代(6～20周龄)的选育试验,在粗蛋白(CP)18%日粮条件下分选育组、非选育组以及对照组(CP24%),N、B基础群中选留15种家系,以采食量为主选性状,以产蛋率和排泄氮量为辅选性状作为选育指标进行试验。结果表明:各世代间采食量无显著差异,同世代各品系间选育组采食量均高于非选育组,但显著低于对照组(P<0.05);世代间产蛋率有增高的倾向,选育组平均累积产蛋率与非选育组比较显著升高(P<0.05),选育组各世代遗传改良极为显著(P<0.01);选育组排泄氮量和血清中尿酸含量在改良2世代后明显低于非选育组和对照组(P<0.05),排泄氮量分别降低9%～17%左右,BN与N、B比较其排泄氮量有明显降低,但各世代遗传改进量不明显。通过选育N、B新品系,能够显著降低排泄氮量,在BN杂种群中效果更明显。

The Effect of Temperature on Growth and Energy Budget of the Polychaete,Neanthes japonica Izuka

Growth and energy budget of the polychaete,Neanthes japonica,at various temperatures(17,20,23,26 and 29℃) were investigated in this study. The growth,as indicated by final dry weight and specific growth rate(SGR),increased with increasing temperature,with the maximum level at 26℃,and then decreased significantly at 29℃. A similar trend was observed in feeding rate,food conversion efficiency(FCE) and apparent digestive rate(ADR). However,no significant differences were detected in ADR among all the temperature treatments. In the pattern of energy allocation,faeces energy was only a small component of energy budget and had little influence on the proportion of food energy allocated to growth. The metabolic energy accounted for a large portion of energy intake for each temperature treatment. The nitrogen excretion was appreciable with changing temperature. The two expenditure terms(respiration energy and excretion energy) in energy budget were the major factors influencing the proportion of food energy allocated to growth. These results revealed that temperature affected the growth of N. japonica mainly by influencing feeding rate and FCE. In addition,regression equations describing the relationship between feeding rate,faecal production,SGR,FCE and temperature were obtained. The optimum temperatures for feeding rate,FCE and SGR were estimated at 25.01℃,24.24℃ and 24.73 ℃,respectively,from the regression equations.

Ligation of Caeca Improves Nitrogen Utilization and Decreases Urinary Uric Acid Excretion in Chickens

This study was carried out to clarify role of ceca in nitrogen nutrition of the chicken. Exp. 1： The effect of cecal ligation on nitrogen utilization and excretion was investigated in chickens fed 5% to 14% protein diet. Irrespective of dietary protein level and different protein sources, the ligation of cecal decreased uric acid excretion and tended to increase nitrogen utilization and balance with the exception of urea-added 10% protein diet. Exp. 2： The effect of cecal ligation on nitrogen utilization and excretion was investigated in conventional and colostomized chickens fed a 5% protein diet or 5% protein diet plus urea. Total nitrogen excretion and uric acid excretion increased by colostomy were depressed by cecal ligation in chickens. Therefore, nitrogen utilization and balance decreased by colostomy were increased by cecal ligation. Urinary nitrogen excretion was significantly decreased by cecal ligation in colostomized chickens, but the cecal ligation did not change fecal nitrogen excretion in chickens fed either diet. Exp. 3： This experiment was carried out to examine the effects of removal of cecal contents on nitrogen utilization, balance and nitrogen excretion in cecally ligated chickens. Total nitrogen excretion was significantly decreased by washing out the cecal contents with saline or antibiotics. The cecal ligation and the removal of cecal contents significantly decreased uric acid excretion in the excreta. There was a highly inverse relationship between microbial counts in the ceca and an excretory amount of uric acid. Exp. 4： In order to examine effects of cecal ligation on microbial activity, microbes were counted and products of microbial fermentation were determined. The ligation of caeca decreased microbial counts, concentrations of acetic, propionic and butyric acids and ammonia concentration of cecal contents. These results suggest that nitrogen metabolism in chickens is affected by possible changes in cecal fermentation caused by preventing the substances from urine and digesta from entering into the ceca.

Effect of Shrimp(Litopenaeus vannamei) Farming Waste on the Growth, Digestion, Ammonium-Nitrogen Excretion of Sea Cucumber(Stichopus monotuberculatus)

In this study, specific growth rate(SGR), ingestion rate(IR), food conversion ratio(FCR), apparent digestion ratio(ADR) and ammonium-nitrogen excretion were determined for sea cucumber(Stichopus monotuberculatus) reared in plastic containers(70 L; 4 containers each diet treatment). Sea cucumbers were fed with five diets containing different amounts of farming waste from shrimp(Litopenaeus vannamei)(100%, 75%, 50%, 25% and 0) and a formulated compound(20% sea mud and 80% powdered algae). Sea cucumbers grew faster when they were fed with diet D(25% shrimp waste and 75% formulated compound) than those fed with other diets. Although IR value of sea cucumber fed with diet A(shrimp waste) was higher than those fed with other diets, both the lowest SGR and the highest FCR occurred in this diet group. The highest and the lowest ADR occurred in diet E(formulated compound) and diet A group, respectively, and the same to ammonium-nitrogen excretion. The contents of crude protein, crude lipid and total organic matter(TOM) in feces decreased in comparison with corresponding diets. In the feces from different diet treatments, the contents of crude protein and TOM increased gradually as the contents of crude protein and TOM in diets increased, while crude lipid content decreased gradually as the crude lipid content in diets increased.