米糠、锯末与蛋鸡粪堆肥过程中氮素的变化特征

探讨米糠、锯末与蛋鸡粪堆肥过程中氮素的变化特征,旨在为制定蛋鸡粪堆肥规模化生产中减少氮素损失、减少氨气挥发的调控措施提供科学依据。试验设4个处理,蛋鸡粪-米糠、蛋鸡粪-锯末,隔天翻堆1次;蛋鸡粪-米糠-锯末、蛋鸡粪-锯末,每天翻堆1次,定期测定物料理化指标。研究表明,堆肥过程中,铵态氮向硝态氮转化受抑制,氮素转化以有机氮与铵态氮间的相互转化以及铵态氮以氨气形式挥发为主,铵态氮主要以氨气形式挥发造成全氮损失。氮素转化与损失与堆肥温度、pH、O2等环境参数有关,高温、高pH促进氨气挥发;充足的氧气可促进铵态氮向微生物量态氮(有机氮)转化。这些参数主要受堆体结构对堆肥氧气供应和有机质分解的影响。因此,可以尝试在米糠和锯末中添加来源广泛的秸秆类辅料,通过改善堆体结构(容重)来减少氮素损失。     

奶牛性别控制技术概述

性别控制是通过对动物的正常生殖过程进行人为干预,使母畜按照人们的愿望所需性别后代的繁殖技术。通过控制奶牛性别不仅可以增强奶牛选择强度,提高繁殖力,加快遗传育种进程,还能促进奶牛向质量型发展,对奶牛业发展具有十分重要的意义。     

康乐县肉牛育肥技术规程

肉牛育肥主要指专用肉牛品种一次性肥育,是肉牛养殖的核心,主要决定于品种、牛舍建设、饲料、饲养管理等关键环节,本文从肉牛品种的选择、标准化牛舍的建设、饲料配方的组成、饲养管理等方面详细总结了西北地区肉牛育肥的成功技术,以供同行参考。     

秦川牛多脊椎性状调查

本文对秦川牛及其杂种牛的脊椎数进行调查,发现其存在多脊椎现象.我们统计了2070头屠宰后肉牛的胸椎（T）和腰椎（L）的数量和相应比例.在秦川牛中共发现T14L6、T14L5、T13L7、T13L5和T12L7五种脊椎数异常性状,其中T14L6和T13L7为多脊椎性状,分别为61和51头,占总数的5.41％.本调查可为高品质肉牛的选育提供参考.     

Formal Address

Summary

A combination of social, economic and physical factors contribute to a decision to migrate for a peasant farmer. Seventy percent of Panamanian land comprises steep topography with low soil fertility. Campesinos (peasant farmers) must perpetually migrate when the land they have settled in the forest loses fertility. This process of continual migration results in deforestation and conversion of forest land to pasture land, which then becomes degraded and subsequently abandoned. Also, government policy has not favored the activities of small land owners, but loans from national banks have financed the promotion of large-scale cattle ranches.

Migration patterns consist of moving to a forested area, clearing it for agriculture for one to three years, and thereafter sowing it for pasture. These conditions eventually result in low agricultural and cattle production. Campesinos therefore sell the land to cattle ranchers who can afford to invest in better management practices. Deforestation in the Canal Watershed, therefore, has left a pattern of land ownership comprising a matrix of a few large landowners, within which remain numerous but small peasant land holdings.

A program for small land owners in and around the Watershed region that promotes social, cultural, and economic stability of land use is needed. Supporting and promoting agroforestry with uses of native tree species associated with subsistence and market crops is an alternative for slowing deforestation and promoting sedentary land use.     

Contras and Comandantes

Summary

In the 1980s, Nicaragua's Sandinista government faced armed mestizo and indigenous insurgencies in much of the nation's central and eastern regions. After the Sandinistas lost the 1990 elections, the in-coming government signed peace agreements with the insurgents and facilitated their return to civilian life. With the war over, the Nicaraguan army greatly reduced its troop strength, leaving tens of thousands of people unemployed. Within a few years, however, many former insurgents and soldiers took up arms again for multiple and complex reasons. This paper examines how three groups that rearmed influenced forest conservation in the buffer zone of Nicaragua's Bosawas Biosphere Reserve between 1991 and 1999. The three groups were the mestizo Northern Front 3-80 (FN 3-80) and the Andrés Castro United Forces (FUAC), made up of former ‘Nicaraguan Resistance’ and Sandinista soldiers respectively, and the Miskito YATAMA movement. The presence of these armed groups impeded the government from taking coercive action to remove farmers from the reserve's nucleus. It also limited the advance of cattle ranching. At times, the groups favored logging, at times they did not. The armed conflicts have tended to keep out prudent foreign investors and encourage the presence of smaller companies willing to take greater risks.     

隐性代谢性酸中毒对肉牛育肥效果的影响

反刍动物过量采食精料会引起瘤胃内乳酸蓄积,使体内酸碱平衡失调、体液pH值下降,重者可导致死亡,轻者影响生长发育。本试验选用育肥期日龄、体重差异不显著的肉牛40头,随机分成4组,按不同日饲喂精料量分组喂养,通过检测生理指标、调整日饲喂精料量,论证长期隐性代谢性酸中毒(瘤胃液pH值在5～5.52、尿液pH值在5.05～5.61之间)对肉牛育肥效果的影响。结果显示在育肥过程中隐性代谢性酸中毒牛群与健康牛群相比增重比低了11.61个百分点。     

Milk production increase following treatment of Dutch dairy cattle with thiabendazole

Summary

In a trial involving 542 dairy cattle on 28 farms, 276 were treated once with thiabendazole within two days of calving. The treated group showed an average increase in milk yielded over the non‐return group of 229.8 kg during the subsequent lactation.

In the treated group, total milk fat production was increased over that of the controls by 7.4 kg per cow; milk protein was increased by 6.9 kg per cow. All treatment parameter differences were highly significant at the 1% level of probability.     

Genetic parameters and single versus multi-trait evaluation of udder health traits

Abstract

Genetic parameters were estimated for lactation average somatic cell score (SCS) and clinical mastitis (CM) for the first three lactations of multiparous Finnish Ayrshire cows. A multi-trait linear sire model was used for estimation of covariance components, and the efficiencies of single- versus multi-trait multi-lactation (MT) sire evaluations were compared. Heritability of SCS and CM in the first three lactations ranged from 0.11 to 0.13 and 0.02 to 0.03, respectively. Within lactation, genetic correlations between SCS and CM ranged from 0.68 to 0.72. Within both traits, across-lactation genetic correlations were lowest between 1 and 3, and highest between 2 and 3, with estimates ranging from 0.75 to 0.86 and from 0.81 to 0.98 for CM and SCS, respectively. Residual and phenotypic correlations were low and ranged from 0.09 to 0.13 and from 0.10 to 0.13, respectively. The absolute difference between genetic and residual correlations was from 0.5 to 0.6. Within-lactation genetic correlations between traits that are much less than unity suggest a multi-trait model for genetic evaluation of mastitis resistance. Comparison of model prediction performance between single-trait (ST) and MT models using a data splitting method showed that the MT model was more stable in predicting breeding values in future records of animals. Especially, for young sires and CM, the SD of EBVs from the MT model was 14 to 23% higher than the ST model, indicating more effective use of information in terms of revealing more genetic variation.