住宅建筑热泵的热源选择

指出了住宅建筑的暖通空调能耗占建筑能耗的比重大，较燃煤取暖而言，热泵技术的节能效果显著。从原理特点、适用性、限制条件、土建和设备建设难度和周期、后期管理维护等方面分析了空气、地表（下）水、土壤、太阳能和污水等热泵热源，探讨了住宅建筑热泵热源选择的总的原则。     

半地下带保温夹套发酵罐的应用

通过对半地下带保温夹套的发酵罐与普通发酵罐24 h的温度变化和6 d的产气量的对比试验分析,结果表明:采用半地下带保温夹套发酵罐发酵,24 h的温度变化缓慢,受外界温度变化影响小,高温持续的时间较长,利于微生物发酵;产气总量多,持续时间长。     

骆驼乳清蛋白对热应激所致大鼠肝氧化损伤的保护作用

本试验旨在研究骆驼乳清蛋白（CWP）对热应激（HS）大鼠肝损伤、氧化应激及肝功能的保护作用。选取6周龄SD大鼠36只,适应性饲养2周后随机分为6组：正常对照组饲喂基础日粮;CWP对照组添加400 mg·kg^-1的CWP;HS组除饲喂基础日粮外,每天进行2 h HS处理,连续8 d;3个CWP干预组分别于每次HS前灌服100、200和400 mg·kg^-1的CWP。试验结束后,取大鼠肝组织,HE染色观察肝组织病理学变化,同时检测肝功能生物标志物、氧化应激标志物水平及抗氧化酶活性。结果表明：CWP降低了HS大鼠血清谷草转氨酶（AST）和谷丙转氨酶（ALT）活性,400 mg·kg^-1的CWP干预效果最好（P<0.01）;400 mg·kg^-1CWP干预组有效降低了HS诱导的大鼠肝组织病理学改变; CWP降低了大鼠肝活性氧（ROS）及丙二醛（MDA）水平,增加了超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、谷胱甘肽过氧化物酶（GSH-Px）活性及谷胱甘肽（GSH）水平,400 mg·kg^-1的CWP干预效果最好（P<0.01）。结果提示,CWP干预能够以剂量依赖性方式降低大鼠肝氧化应激,增加抗氧化系统防御能力,从而缓解HS所致大鼠肝损伤。     

Egg production,fertility, hatchability and immune responses of some chicken strains under high ambient temperatures

This experiment was designed to investigate and compare the egg production, fertility, hatchability and immune responses of some local developed Egyptian chicken strains under high ambient temperatures. A total of 108 (26 weeks old) laying hens of Matrouh, Silver Montazah, Mandarah and Inshas (9 hens × 3 replicates × 4 strains) were used to evaluate the impact of thermal stress (24-34ºC) during summer season (June, July and August) on egg production, fertility, hatchability and immune responses. The obtained results revealed that final body weight (FBW/g) and body weight change (BWC/g) among different chicken strains were not affected. The daily feed consumption (FC/g) and feed conversion ratio (FCR) for Silver Montazah and Inshas strains were significantly (p ≤ .05) higher than those of Matrouh and Mandarah strains. The mean egg production (EP/%) and egg mass (EM) for Silver Montazah and Inshas strains were significantly (p ≤ .05) higher than those of Matrouh and Mandarah strains. The highest percentages of hatchability of total eggs (HTE) and fertile eggs (HFE) were recorded in Inshas chickens, while the lowest value was recorded in Mandarah chickens. Also, the highest embryonic mortalities (p ≤ .05) and lowest chick weight at hatch (CWH/g) were recorded in Mandarah chickens compared with the other strains. The highest values for antibody titres against phytohemagglutinin-P (PHA-P) were recorded in Mandarah chickens, while the least values were recorded in Inshas chickens.     

Ultrasonographic findings of the corpus luteum and the gravid uterus during heat stress in dairy cattle

The objectives of this study were to assess alterations in, echogenic appearance, size and blood flow in the corpus luteum, the placentomes and the blood flow in umbilical and uterine arteries that heat stress can cause in cooled pregnant dairy cows. Pregnant cows were allocated in two groups and the gravid uteri, along with the ipsilateral corpora lutea were examined during the winter (group W, n = 9) or the summer (group S, n = 10). The grey-scale ultrasound and colour flow imaging of the corpus luteum and placentome were performed. In addition, the umbilical and uterine artery diameters and haemodynamic parameters in the vessels were calculated. At the time of ultrasonographic examination, cortisol concentrations were higher, and progesterone levels tended to be lower in group S compared to group W. The grey-scale ultrasound evaluation of corpora lutea and placentomes was lower in group S compared to group W. The diameter of umbilical artery and the blood volume in the vessel were less in group S than in group W. We infer that heat stress affects foetal blood supply and possibly the structure of placentomes and corpora lutea, but it differently affects the blood flow characteristics in the umbilical and uterine arteries.     

Production,chemical composition,and fatty acid profile of milk from buffaloes fed with cupuaçu (Theobroma grandiflorum) cake and murumuru (Astrocaryum murumuru) cake in the Eastern Amazon

The objective was to evaluate the effect of concentrate supplementation using by-products of the Amazonian industry on milk production, milk composition, and milk fatty acid profile of dairy buffaloes. Twelve lactating buffaloes (544.5 ± 35.6 kg, 6.4 ± 2.2 years old, 59 ± 6 days in milk) were allotted in a pasture of Mombaça grass and managed under rotational grazing (4 days occupancy/28 days rest). A 3 × 3 Latin square was adopted, and each animal alternately received three supplementary treatments based on corn bran + soybean meal or cupuaçu cake or murumuru cake for 21 days per treatment. Murumuru cake increased the levels of lauric acid and myristic acid in the milk (p < 0.05). Murumuru cake reduced the unsaturated fatty acid contents in the milk compared with animals fed control diet or cupuaçu cake (24.27% vs. 25.24% vs. 25.08%). The n-6/n-3 ratio was 2.6, 1.97, and 2.0 in the control, cupuaçu, and murumuru groups, respectively. Based on this parameter, cakes made from cupuaçu as well as murumuru could be considered to be adequate for inclusion in dairy water buffalo feed. However, the murumuru cake addition requires some caution because its use induces the secretion of higher levels of lauric and myristic fatty acids that are related to human cardiovascular disease.     

Single nucleotide polymorphism in avian uncoupling protein gene is associated with thermoregulation in chicks

Avian uncoupling protein (av-UCP) is a key protein for thermoregulation in poultry. A single nucleotide polymorphism (SNP) in the av-UCP gene has been reported in chickens. The purpose of the current study was to clarify the association between this av-UCP gene mutation and thermoregulation in chickens. Wild and mutant type chicks for the av-UCP gene SNP (g. 1270 of the av-UCP gene exon 3 with C to T substitution and amino acid substitution) were exposed to high ambient temperature. Rectal temperature, radiation temperature on the body surface, and the expression of heat dissipation behavior (wing drooping and panting) during heat exposure were measured. In addition, oxygen consumption rate in the thermoneutral zone in wild and mutant type chicks was measured. Changes in wing temperature during heat exposure in wild-type chicks were lower than those in mutants. The latency of continuous wing drooping during heat exposure in wild-type chicks was shorter than in mutant chicks. It was also found that the SNP in the av-UCP gene caused reduced oxygen consumption. These results suggest that the av-UCP gene mutation affects thermoregulation, especially heat production, in chickens.     

我国不同奶业产区规模化牧场饲料结构分析

在奶牛养殖规模化水平不断提高,养殖成本日益增加,且区域间差异明显的背景下,饲料作为奶牛养殖主要投入品,了解其在规模化牧场生产成本中的结构对于优化奶牛日粮结构、降低养殖成本、缩小区域间养殖效益差距等具有重要意义。本文利用2018—2020年规模牧场月度调研数据,分析了我国规模化牧场饲料结构情况。研究发现,大城市周边产区和南方产区的精饲料和粗饲料的比例相对更加科学,华北产区仍有较大提升空间,并且玉米、豆粕、玉米青贮和苜蓿草在日粮中占有较大比重,达到84.62%;不同产区奶牛日粮结构具有明显差距,玉米青贮和苜蓿草在西北产区占比最高,玉米和豆粕在南方产区占比最高。注重发挥区域优势,加大优质粗饲料和可替代饲料的利用,有利于降低养殖成本,提高养殖的科学性和可持续性。     

拷贝数变异在畜禽中的研究进展

拷贝数变异（copy number variation,CNV）具有多种形式的变异结构,在品种多样性、生物进化和疾病相关性等研究中起着重要作用,并具有片段长度大、覆盖范围广等特点。随着分子生物学的发展及DNA测序技术的日渐成熟,人们对遗传变异的研究不断向DNA分子水平深入,多态性标记在畜禽育种中已逐渐成为动物育种研究的趋势和主流。由于CNV对基因的调控和表达所造成的影响更为显著,因此,CNV在重要畜禽中的研究越来越多。目前,已检测出大量有关畜禽重要经济性状的基因序列变异,并有许多研究均表明CNV与动物的重要经济特征及疾病的发生有关。笔者主要通过参考国内外相关的研究报道,简述了CNV的相关研究背景、概念、突变机制,归纳总结了CNV对牛、羊、猪、鸡的经济性状、繁殖性状和疾病调控的影响,以期通过对这些重要畜禽的基因组学研究揭示其适应性遗传机理和表型性状差异的遗传基础,开发相应的分子遗传标记,为畜禽的标记辅助选育提供理论基础。     

保温型刚性护面渠道设计

在刚性面层下设置一道性能良好的保温层来防止基土冻结,可以从根本上解决冻胀破坏的问题。这种带保温层的刚性护面渠道称为保温型刚性护面渠道,根据热工原理,提出了保温型刚性护面渠道横断面设计在构造方面的要求,进一步推导出计算保温层厚度的有关公式,并给出算例,还指出了需要进一步研究和探讨的问题。