助产对奶牛产后子宫菌群的影响

在奶牛养殖业中,难产是奶牛临床上的常发病,助产是处理难产的常用手段。助产的发生会导致母牛受胎率降低、冻精使用量增加、空怀时间增加和首次配种时间后移等繁殖问题。本研究从细菌学角度分析助产对奶牛产后子宫菌群的影响,以期为提高牧场受胎率提供数据参考。在宁夏地区某大型奶牛场,以助产和非助产奶牛为研究对象,在产后45 d进行子宫灌洗,采集灌洗液样本共7份。通过细菌分离培养、16S rRNA测序等方法分离细菌。结果共分离出10个细菌属,12种细菌,其中,非助产奶牛子宫冲洗液中分离出链霉菌属、链球菌属、肠杆菌属、葡萄球菌属、气球菌属5个属的细菌;助产奶牛子宫冲洗液分离出志贺菌属、不动杆菌属、假单胞菌属、棒状杆菌属、芽胞杆菌属、气球菌属、肠杆菌属、葡萄球菌属、链球菌属等9个属的细菌。本研究的结果表明,助产和非助产奶牛子宫菌群差异显著,助产导致子宫内菌群多样性增加。     

Gonadotropin‐Releasing Hormone Administration to Dairy Cows without a Corpus Luteum 4 Weeks after Calving Increases Reproductive Performance

This field study investigated whether the administration of a single dose of gonadotropin‐releasing hormone (GnRH) to dairy cows without a corpus luteum (CL) 4 weeks after calving can improve reproductive performance. Holstein dairy cows underwent ultrasonography to assess the presence of ovarian structures at 29.2 ± 5.2 days post‐partum, and cows were divided into two main groups based on the presence (CL group, n = 230) or absence (non‐CL group, n = 460) of a CL. The non‐CL group was further randomly divided into two subgroups based on the administration of GnRH (non‐CL GnRH group, n = 230) or no GnRH (non‐CL control group, n = 230). Subsets of cows from non‐CL control (n = 166) and non‐CL GnRH (n = 175) groups received a second ultrasonography at 44.5 ± 5.4 days post‐partum to assess CL formation. The percentage of cows with CL at the second ultrasonography was greater in the non‐CL GnRH group (70.9%) than in the non‐CL control group (53.0%, p = 0.0006). The hazard of the first post‐partum insemination by 150 days in milk (DIM) was higher in the CL group than in the non‐CL control group (hazard ratio [HR]: 1.36, p = 0.001). The probability of a pregnancy to the first insemination was higher in non‐CL GnRH (odds ratio [OR]: 1.50, p = 0.04) and CL groups (OR: 1.55, p = 0.03) compared to the non‐CL control group. Furthermore, the hazard of pregnancy by 210 DIM was higher in non‐CL GnRH (HR: 1.30, p = 0.01) and CL (HR: 1.51, p = 0.0001) groups than in the non‐CL control group. In conclusion, administration of GnRH to dairy cows without a CL 4 weeks after calving was associated with an increase in ovulation and improved reproductive performance.     

Stability of 0.5% cidofovir stored under various conditions for up to 6 months

Objective To evaluate the effect of time, temperature and storage vial material on the antiviral activity of 0.5% cidofovir solution. Procedures Commercial 7.5% cidofovir solution for injection was diluted with normal saline to a 0.5% concentration. Aliquots were stored in plastic and glass vials at 4, ?20, and ?80 °C for 30, 60, 120, and 180 days. Antiviral activity against feline herpesvirus was evaluated in a virus titration assay at time zero (baseline) and at each subsequent time point. Results Cidofovir caused a fourfold log reduction in virus titer at baseline and at each time point and for each storage condition (P < 0.001). Conclusion 0.5% cidofovir demonstrated stable antiviral activity when stored for up to 6 months in glass or plastic, at 4, ?20, and ?80 °C.     

Isolation,Identification and Enrichment of Type A Spermatogonia from the Testis of Chinese Cross‐Bred Buffaloes (Swamp × River)

The proportion of type A spermatogonia in the isolated testis cells is a prerequisite for conducting experiments and the manipulation of these germ cells. Thus, this study was designed to examine the wide range of strategies for the isolation, identification and enrichment of type A spermatogonia in pre‐pubertal buffalo calves (3–6 months). Histological findings revealed the presence of maximum number of type A spermatogonia at 5 months, which was further confirmed by DBA immunohistochemistry. In a newly modified strategy for the isolation of testis tissues, mincing followed by trituration and two rounds of digestion with collagenase, hyaluronidase and DNase yielded more than 95% testis cell population. Differential plating with laminin, poly‐l ‐lysine and gelatin significantly (p < 0.05) affected the purity of type A spermatogonia. Among these extracellular matrix (ECMs) molecules, laminin and gelatin performed well and reached at a purity of 39.38 ± 1.21% and 32.15 ± 1.60%, respectively. In addition, combination of laminin and gelatin followed by Percoll centrifugation performed the best and yielded >90% type A spermatogonial purity. Moreover, viability of the cells was not affected (p > 0.05) irrespective of different enrichment methods. In conclusion, type A spermatogonia isolation and enrichment system was developed using different ECM molecules in buffaloes, which will aid in solving wide range of problems especially fertility‐related problems and transgenic animal production in buffaloes.     

Using “Uterine Index” to diagnose embryonic death in mares

Embryonic death plays an important role in infertility in mares, and most of embryonic mortality occurs at an early stage (before day 40) of pregnancy. Previous investigations focused on B-mode sonographic images to determine abnormal pregnancy; however, no study has provided a quantitative and objective method to diagnose embryonic death. Here we developed a new index, “Uterine Index,” using color Doppler sonography to describe alterations of uterine blood flow in physiological and pathological gestations during early gestation. Six Trotter mares were used in this study. The pregnancies were interrupted with a prostaglandin F2α (PGF_2α) analog (tiaprost) at days 25, 30, and 40. Three gestations were investigated in each stage. After the PGF_2α administration, these mares were examined every 8 hours until the embryonic vesicles were not visible on ultrasound. In the control group, three pregnancies were examined daily from days 12 to 60. The embryo size was measured in B-mode sonography, and the blood flow in uterine arteries was examined in Doppler ultrasound. The resistance index (RI) and uterine index (UI) were calculated. In the control group, the RI values of uterine artery were lower in pregnant side compared with that of the non-pregnant side from day 15 on, and the difference became greater as the pregnancy advanced (P < .05). The UI was close to 0 before week 3 and increased to approximately 10 after week 4. In the PGF_2α-treated group, the UI values reduced from pregnancy level to approximately 0. As early as 32 hours before embryonic death, we observed a significant difference of UI values between control and treated mares. On the contrary, the embryo size of treated mares was not different from that of normal mares. Through the analysis of all recorded UI values, we suggest that the UI values 10 and 5 are good values for distinguishing normal pregnancy (UI >10) from embryonic death (UI < 5). If the UI values are located between 10 and 5, a reexamination at intervals of 1 to 3 days is recommended. Our findings demonstrate that the UI is a useful method to diagnose and predict embryonic death in mares by providing reliable and objective information.     

Effects of a Progesterone‐Based Oestrous Synchronization Protocol in 51‐ to 57‐Day Postpartum High‐Producing Dairy Cows

The aim of this study was to investigate the effect of applying a progesterone‐based oestrous synchronization protocol at 51–57 days postpartum in high‐producing dairy cows. The data analysed were derived from 1345 lactating cows. Cows between 51 and 57 days postpartum were assigned to the groups: control, PRID (receiving a progesterone‐releasing intravaginal device for 9 days, and prostaglandin F_2α 24 h before PRID removal) or GnRH–PRID (the same as the PRID group plus GnRH at PRID insertion). Oestrus was detected by using pedometers and confirmed by examination of the genital tract at AI. Oestrous and conception rates before days 71–77 postpartum, pregnancy loss in early pregnant cows or the cumulative conception rate registered on day 120 postpartum were considered as the dependent variables in four consecutive logistic regression analyses. Based on the odds ratios, the oestrous rate increased by a factor of 1.73 in cows showing oestrus before treatment for each unit increase in the number of previous oestruses; decreased by a factor of 0.44 in the control group with respect to the treatment groups; and by a factor of 0.61 in cows without luteal structures at treatment with respect to cows with corpora lutea. The conception rates of cows inseminated before days 71–77 postpartum remained similar across the groups, whereas the likelihood of pregnancy loss for cows becoming pregnant during this period was 0.11 times lower in the PRID group than in the control. Based on the odds ratio, the likelihood of a higher cumulative conception rate on day 120 postpartum: increased in cows showing oestrus before treatment by a factor of 1.41 for each unit increase in the number of previous oestruses, was reduced 0.56‐fold in control cows compared with treated cows, and was also reduced by a factor of 0.98 for each kilogram of milk production increase recorded at treatment. In conclusion, although oestrous synchronization programmes performed in this study did not improve fertility, cows treated with progesterone could be inseminated earlier than untreated cows, such that the treatments increased the cumulative pregnancy rates determined on day 120 postpartum. In addition, fewer pregnancy losses were observed in early pregnant cows in the PRID group than the GnRH–PRID group.     

日粮能量水平对6～10周龄扬州鹅生产性能与脂肪沉积的影响

本研究旨在探讨日粮能量水平对6～10周龄扬州鹅生产性能和脂肪沉积的影响.选用35日龄、体重相近的扬州鹅200只,随机分成4组,每组5个重复,每个重复10只,公母各1/2.Ⅰ～Ⅳ组日粮能量水平分别为10.11、11.19、12.37和13.45MJ/kg,试验期35 d.结果表明:(1)Ⅱ组的平均日采食量显著高于Ⅳ组,Ⅲ和Ⅳ组的料重比显著低于Ⅰ和Ⅱ组(P<0.05);(2)Ⅳ组的屠宰率和腿脂率显著高于Ⅰ组(P<0.05),Ⅲ和Ⅳ组的腹脂率极显著高于Ⅰ组(P<0.01);(3)日粮能量水平对血清总胆固醇、谷丙转氨酶、谷草转氨酶、尿酸、葡萄糖、碱性磷酸酶和乳酸脱氢酶无显著影响(P>0.05),Ⅲ组的血清高密度脂蛋白和低密度脂蛋白显著高于Ⅱ组(P<0.05),而极低密度脂蛋白和甘油三酯显著低于Ⅱ组(P<0.05),Ⅲ组的血清总蛋白和白蛋白显著低于Ⅰ组(P<0.05).由此可知,高能量日粮显著提高6～10周龄扬州鹅的屠宰率、腹脂率和腿脂率,降低采食量和料重比.但是,腹脂率过高(5.4%)将导致饲料成本增加.因此,建议6～10周龄扬州鹅日粮的适宜能量水平为12.37MJ/kg.     

Optimal dietary lysine to threonine ratio in pigs (30–110 kg BW) derived from observed dietary amino acid efficiency

Optimal ratio of lysine (Lys) to threonine (Thr) in diets for growing barrows [genotype: Piétrain × (Large White × German Landrace)] was established at 30, 50, 70, 90 and 110 kg body weight (BW). N balance studies were conducted with diets based on constant mixture of wheat, barley, soybean meal and field peas. Supplementation of crystalline amino acids (AA) provided diets with Lys (diet A) and Thr (diet B) in first limiting position. For each BW range, totally 28 individual N balance data were utilized for assessing model parameters (exponential N utilization model) of dietary efficiency of Lys and Thr, respectively. Observed maximal dietary efficiency of Lys and Thr provided the database for conclusion of optimal dietary Lys to Thr ratio. Based on applied experimental conditions, BW dependent Lys to Thr ratio could not be concluded. On average, the dietary ratio Lys to Thr = 1:0.61 ± 0.02 was obtained as optimal for growing pigs.     

Energy requirements of puppies of two different breeds for ideal growth from weaning to 28 weeks of age

To ensure an optimal growth is crucial in raising healthy dogs, especially in large and giant breeds. Dogs with a moderate growth velocity tend to have lesser problems with developmental orthopaedic diseases than those with forced or maximum weight gain. In this study, the energy needs of growing dogs from two different breeds (Beagles as a medium‐size breed and Foxhound crossbreds as a large‐size breed) to ensure a growth development as recommended by the National Research Council (NRC) were determined at the age of 6–28 weeks. After weaning at the age of 6 weeks, the food rations sufficient to meet the energy requirements of each individual puppy were adjusted every other day according to growth level, guaranteeing a development consistent with the recommended weight curve for the respective breed size. The food and therefore energy intake of the puppies was registered daily; it ranged from 0.72 to 2.34 times the maintenance requirements with little effect of age. During the whole period, however, there was a consistent breed difference: Foxhound‐Boxer‐Ingelheim Labrador crossbreds (FBIs) had higher energy intakes expressed as multiples of maintenance than Beagles, suggesting that during the major period of growth, the energy requirement is not a function of age. Adult Beagles and FBIs showed similar differences in energy requirements as already during growth as shown in this study. This indicates that breed differences in energy requirements have already to be taken into account during growth. On the other hand, the results showed clearly lower energy needs for growth in these two different breeds than recommended in the NRC.