母鼠妊娠期铅镉联合暴露对新生鼠体内微量元素含量的影响及NAC的保护效应

为了研究母鼠妊娠期铅镉联合暴露对新生鼠体内微量元素Cu、Fe、Zn、Mn和Se及N-乙酰半胱氨酸(N-Ace-tylcysteine,NAC)的保护作用,35只怀孕SD母鼠被随机分为7组,即A组为对照组(饮用蒸馏水)、B组为铅组(300 mg/L)、C组为铅+NAC组(300 mg/L+20 mmol/L)、D组为镉组(10 mg/L)、E组为镉+NAC组(10 mg/L+20 mmol/L),F组为铅+镉组(300 mg/L+10 mg/L)、G组为铅+镉+NAC组(300 mg/L+10 mg/L+20 mmol/L).采用饮水染毒.染毒时间为21 d,分娩后应用电感耦合等离子体质谱仪(Inductively coupled plasma mass spec-troscopy,ICP-MS)检测新生鼠体内微量元素Cu、Fe、Zn、Mn和Se含量.结果表明,与对照组比较,各染毒组新生鼠体内微量元素Cu、Fe、Zn、Mn和Se含量均显著低于对照组(P<0.05).D组较B组降低明显,F组降低最为显著,铅镉联合表现协同毒性效应,镉在铅镉联合毒性损伤中发挥主要作用,与各染毒组比较,NAC保护组新生鼠体内微量元素Cu、Fe、Zn、Mn和Se含量均有不同程度升高,部分组间有显著差异(P<0.05),说明NAC对铅、镉致新生鼠体内微量元素平衡紊乱具有一定的保护作用.     

新疆农业产业集群现状及发展对策研究

农业产业集群是推动农村经济发展的重要产业组织形式。现以新疆为研究对象,从新疆农业产业集群的发展优势和现状出发,结合区位商进行分析,发现当前新疆农业产业集群主要面临产业链条短、市场需求反应慢、支持服务体系不健全等问题,最后从产业链、科技投入、市场需求和网络体系等角度提出新疆农业产业集群发展的对策。     

COMPARISON OF MAGNETIC RESONANCE IMAGING AND MYELOGRAPHY IN 18 DOBERMAN PINSCHER DOGS WITH CERVICAL SPONDYLOMYELOPATHY

Eighteen Doberman pinscher dogs with clinical signs of cervical spondylomyelopathy (wobbler syndrome) underwent cervical myelography and magnetic resonance (MR) imaging. Cervical myelography was performed using iohexol, followed by lateral and ventrodorsal radiographs. Traction myelography was performed using a cervical harness exerting 9 kg of linear traction. MR imaging was performed in sagittal, transverse, and dorsal planes using a 1.5 T magnet with the spine in neutral and traction positions. Three reviewers independently evaluated the myelographic and MR images to determine the most extensive lesion and whether the lesion was static or dynamic. All reviewers agreed with the location of the most extensive lesion on MR images (100%), while the agreement using myelography was 83%. The myelogram and MR imaging findings agreed in the identification of the affected site in 13-16 dogs depending on the reviewer. MR imaging provided additional information on lesion location because it allowed direct examination of the spinal cord diameter and parenchyma. Spinal cord signal changes were seen in 10 dogs. Depending on the reviewer, two to four dogs had their lesions classified as dynamic on myelography but static on MR images. Myelography markedly underscored the severity of the spinal cord compression in two dogs, and failed to identify the cause of the signs in another. The results of this study indicated that, although myelography can identify the location of the lesion in most patients, MR imaging appears to be more accurate in predicting the site, severity, and nature of the spinal cord compression.     

Changes in the quality of meat (Longissimus thoracis et lumborum) from Kamieniec lambs during long‐term freezer storage

The aim of this study was to determine changes in the quality of lamb meat (Longissimus thoracis et lumborum), which was vacuum‐packaged and freezer‐stored (?26°C) for 6 and 12 months. The experiment was performed on 12 male lambs of the Kamieniec Longwool breed, raised to 106 days of age. In comparison with fresh meat, thawed meat was characterized by lower ash content, higher pH, greater natural drip loss and cooking loss, and lower scores for taste intensity. Vacuum packaging and low‐temperature storage protected lamb meat against oxidative changes, and alleviated the adverse effects of oxidation on the color, aroma and taste of meat. It can be concluded that freezer storage (?26°C) of vacuum‐packaged meat can help meet consumer demand for lamb meat products in periods when fresh meat is unavailable. However, it should be noted that long‐term frozen storage induces undesirable changes in meat quality, including a decrease in water‐holding capacity and taste intensity.     

Combined treatment with oestradiol benzoate,d‐cloprostenol and oxytocin permits cervical dilation and nonsurgical embryo recovery in ewes

This study examined the feasibility of transcervical embryo recovery after the hormonal treatment to induce cervical dilation, following the 7‐day oestrous synchronization protocol in multiparous Santa Inês ewes. A total of 23 cyclic ewes received two doses of 37.5 μg of d‐cloprostenol by latero‐vulvar route 7 days apart. After the second injection of d‐cloprostenol, the ewes were checked for oestrus (every 12 hr) and then mated by fertile rams throughout the oestrous period. All ewes received 37.5 μg of d‐cloprostenol (latero‐vulvar) and 1 mg of oestradiol benzoate by either intramuscular (EBim group; n = 12) or intravaginal (EBivg group; n = 11) route 16 hr before embryo flushing. Twenty minutes before the flushing, 50 IU of oxytocin were administered intravenously. The oestrous response (i.e., the percentage of ewes that showed signs of oestrous behaviour after the second d‐cloprostenol injection) was 91.3% (21/23). The proportion of successfully penetrated ewes (81.8% compared with 80.0%), the mean duration of embryo flushing (24.7 ± 2.0 min compared 26.2 ± 1.9 min), the flushing fluid recovery rate (94.8 ± 1.3% compared with 91.0 ± 2.9%) and the average number of structures recovered per ewe (0.5 ± 0.4 compared with 0.8 ± 0.4) did not vary (p > 0.05) between the EBim and EBivg groups. Viable embryos were recovered from 41.2% (7/17) of successfully penetrated ewes. It can be concluded that nonsurgical (i.e., transcervical) embryo collection can be performed in oestrous‐synchronized Santa Inês ewes pretreated with d‐cloprostenol, oxytocin and oestradiol benzoate, with the latter hormone administered by either the intramuscular or intravaginal route.     

Early luteal development in Santa Inês ewes superovulated with reduced doses of porcine follicle‐stimulating hormone

The aim was to compare the early luteal development in ewes superovulated with different doses of pFSH. Twenty‐nine Santa Inês ewes received a progesterone device (CIDR®) for 8 days. Gonadotrophic treatment started on Day 6: G200 (control, n = 9, 200 mg); G133 (n = 10, 133 mg); and G100 (n = 10, 100 mg of pFSH). On Day 6, all females received eCG (300 IU). B‐mode and spectral Doppler ultrasonography were performed daily during the early luteal phase (Days 11–15) to monitor the development of corpora lutea (CLs; dimensions) and ovarian arteries indices. CLs were also classified as normal or prematurely regressed (PRCL) on Day 15 by videolaparoscopy. Ewes from G100 and G133 showed gradual increase in luteal diameter during the early luteal phase (p < 0.001), whereas G200 animals presented increase from Day 11 to Day 13, and then decrease on Days 14 and 15 (p < 0.001). The G200 females showed greater percentage of PRCL (45.20%) than those of the other groups (p < 0.001). The normal CLs number was greater in G100 than in G133 (p = 0.04), while the PRCL number was greater in G200 than in the other groups (p = 0.03). Resistive index (RI) was greater in G200 than in G100 (p = 0.02). RI was lower in Day 12 than Day 15 (p = 0.02). Pulsatility index (PI) was greater on Days 14 and 15 (p < 0.01). In conclusion, the lowest dose of pFSH (100 mg) can be considered sufficient for an efficient superovulatory response in sheep, producing better CLs development dynamic in early luteal phase and ovarian blood perfusion and smaller number of PRCL than the traditional (200 mg) pFSH dose.     

Endometrial gene expression in primiparous dairy cows at the end of the voluntary waiting period is affected by nutrition: Total mixed ration vs increasing levels of herbage allowance

The study postulated that differential nutritional management during the early lactation period would be reflected in endometrial expression of genes related to embryo growth at the end of the voluntary waiting period. Thus, the effect of the combined use of total mixed ration (TMR) and grazing under different herbage allowances during the first 75 days post‐partum (DPP) on endometrial gene expression was evaluated in primiparous dairy cows. Cows were blocked by body weight, age and body condition score and randomly assigned to three grazing treatments: high (HA, 30 kg DM per cow per day), medium (MA, 15 kg DM per cow per day) and low (LA, 7.5 kg DM per cow per day) herbage allowance (mixed pasture, 2,600 kg DM per ha) plus 8 kg DM of supplement or TMR (55% forage, 45% concentrate) fed ad libitum (TMR) from calving to 75 DPP. At 57 DPP, cows were synchronized for oestrus (day 0, 68 DPP) and at day 7, endometrial biopsies were obtained. The nutritional treatment did not affect insulin, IGF‐1 and leptin concentrations on days 0, 4 or 7. Expression of IGF1, IGFBP3, IGFBP4, ADIPOR1 and ADIPOR2 mRNA was significantly affected by the nutritional treatment. Endometrial IGF1 and IGFBP4 mRNA were twofold greater in TMR and HA than MA and LA cows. Expression of IGFBP3 and ADIPOR1 mRNAs was greater in TMR and HA than MA cows, but did not differ from LA cows. All groups had greater expression of ADIPOR2 mRNA than MA cows. This study provided solid evidence of the importance of nutritional management during early lactation on uterine environment at the end of the voluntary waiting period. The greater expression of genes related to embryo growth and uterine function (IGF system, progesterone and adiponectin receptors) in cows fed diets maximizing energy intake suggests a favourable environment for embryonic growth, which may explain the improved reproductive performance of cows in good energy balance.