应用Ovsynch技术促进奶牛产后卵巢周期活动恢复的研究

本研究通过对产后20d体况评分为2.75～3.5、子宫复旧较好、卵巢无明显的卵泡和黄体活动的奶牛应用Ovsynch(同期诱导排卵)技术促进卵巢活动,结果表明:采用GnRH+CIDR+PG方法以及两次PG法对促进奶牛产后卵巢周期活动恢复作用明显,与对照组相比,差异性显著(P0.05)。     

Dose dependent disposition of sulphadimidine and of its N4‐acetyl and hydroxy metabolites in plasma and milk of dairy cows

Summary

The disposition of sulphadimidine (SDM) and of its N₄‐acetyl (N₄‐SDM) and two hydroxyl metabolites, 6‐hydroxymethyl‐ (SCH₂OH) and 5‐hydroxyasulphadimidine (SOH), was studied in plasma and milk of dairy cows following intramuscular or intravenous administration of sulphadimididine‐33.3% at doses of 10, 45, 50, and 100 mg/kg. The main metabolite in plasma as well as in milk was SCH₂OH. The metabolite percentages, the final plasma elimination half‐lives, and the time of peak SDM concentrations in milk are presented for different dosages. The concentrations of SDM and its metabolites in milk ran parallel to those in plasma beyond4 hours p.i. The metabolite concentrations in plasma and milk were lower than those of the parent SDM. Sulphate and glucuronide metabolites could not be detected in milk.

At high doses (45 mg/kg or more) and SDM plasma concentrations exceeding 20 μg/ml, a capacity limited metabolism of SDM to SCH₂OH was noticed, viz, asteady state concentration of SCH₂OH and a biphasic elimination pattern for SDM and SCH,OH in plasma and milk.

The mean ultrafiltrate ratios of the milk to plasma concentrations with respect to SDM, SCH₂OH, SOH, and N₄‐SDM were: 0.69, 0.22, 020, and 0.63, respectively.

The total amount of SDM and its metabolites recovered from the milk after milking twice daily over the whole experimental time was less than 2% of the applied dose.

A bioassay method allowed of detecting qualitatively SDM concentrations exceeding 0.2 μg/ml in plasma or milk. Withholding times for edible tissues and milk are suggested.     

定时输精程序（Ovsynch／TAI）在奶牛繁殖上的应用效果

应用生源结合诱情素的定时输精程序。对不发情、卵巢静止的奶牛以及产后60～75天发情正常的奶牛进行试验，结果表明：不发情奶牛应用定时输精程序处理后，情期受胎率为74％，而正常配种的情期受胎率为49．8％．提高24．2个百分点；对卵巢静止的奶牛应用定时输精程序处理后有效率为97．2％，情期受胎率为64％：对产后60-75天发情正常的奶牛应用定时输精程序处理后情期受胎率为68．6％，按正常方式配种的奶牛情期受胎率为45．6％，情期受胎率提高23个百分点。结论：定时输精程序在奶牛繁殖上的应用具有明显效果．适合国内饲养条件下任何奶牛场使用。     

Effect of β -glucanase and xylanase supplementation of barley- and rye-based diets on caecal microbiota of broiler chickens

1. The aim was to investigate the effect of grain type (barley or rye) and exogenous enzymes (β-glucanase or xylanase) on the composition of chicken caecal microbiota as examined by classical culturing and molecular techniques (fluorescent in-situ hybridisation (FISH) and terminal-restriction fragment-length polymorphism (T-RFLP)). 2. Plate counting revealed higher total numbers of anaerobic bacteria, lactic acid bacteria and yeasts in caecal contents of birds fed with rye-based diets than in birds fed with barley-based diets. 3. As assessed by FISH analysis, the most abundant bacterial groups in the broiler caeca were Clostridium coccoides-Eubacterium rectale followed by Bacteroides sp., Lactobacillus sp./Enterococcus sp., Bifidobacterium sp. and Enterobacteriaceae. For both cereal types, the enzyme supplementation significantly decreased the relative amount of Enterobacteriaceae. 4. The T-RFLP profiles indicated that the caecal microbiota of birds receiving rye-based diets was more diverse than that of birds fed on barley-based diets. 5. Irrespective of the method applied, the results indicate that the cereal type as well as the exogenous enzyme supplementation influence the microbiota in broiler chicken caeca, and may have the effect of reducing potentially pathogenic Enterobacteriaceae populations.     

Comparison and Correlation of Agronomic Characteristics and Fermentation Quality of Different Types of Hybrid Corn北大核心CSCD

In order to select the silage corn (Zea mays L.) hybrids suitable for planting in the northern part of Shanxi Province, the agronomic characteristics of 16 hybrid corn and the fermentation quality of silage prepared after castration were measured. The results showed that in agronomic characteristics, DJJ 26 had the highest plant height and ear height, but its stem diameter was the thinner. The green-leaf number ranked in the top three is TY168, QS 30 and GK516. For yields, DF26 had the highest yield. For ensiling characteristics, except for DH679, TY511, all hybrids were below 4. 20 for pH values. The significantly positive correlation was found between fresh grass yield and stem diameter, green-leaf number, stem weight, ear weight, leaf weight. The Lactic acid content of whole plant corn silage was positively correlated with green-leaf number. Therefore, the corn hybrids with thick stems, more green leaves and good panicle traits should be selected for silage use. The JD65 and TY168, GK516 and QS30 have good growth and fermentation performance, thereby, could be selected for silage corn in the northern part of Shanxi Province. © 2019 China Agricultural University. All rights reserved.     

Effects of altitude and variety on nutrient levels and epiphytes of oats北大核心CSCD

Oat crops are a major animal feed source in the Qinghai-Tibetan plateau and nearby areas. Typically，the crops are used for making silage rather than hay because of frequent rain at harvest in autumn. However，there is little data on how the yield，forage quality and levels of epiphytes that may affect silage quality of different oat varieties are affected by altitude. Therefore，four oat varieties（Longyan No. 3，Longyan No. 5，Baiyan No. 2 and Bayou No. 3） were planted in 8 localities forming an altitude gradient： Huangzhong （2295 m），Tianzhu （2797 m），Shandan （2860 m），Hezuo （2957 m），Haiyan （3052 m），Maqu （3474 m），Maqin （3765 m）and Chengduo （4217 m）. Measurements included crop yield and dry matter （DM），water soluble carbohydrate （WSC），crude protein （CP），neutral detergent fiber （NDF）and acid detergent fiber （ADF）contents，and counts of lactic acid bacteria （LAB），molds，yeasts and aerobic bacteria. It was found that there were significant altitude and variety effects on fresh yield，nutritional quality and microbial epiphyte counts. With increase in altitude，fresh yield，WSC，NDF and LAB counts increased（P<0.05），as much as 284. 00%，15. 49%，10.81% and 11.60% increment were observed at Chengduo site than that at Huangzhong，respectively；meanwhile DM，CP and yeast and mold counts were reduced by 15. 67%，36.27%，23.53% and 7.75% at Chengduo compared with Huangzhong site，respectively. Among the four tested varieties，Longyan No. 5 had the highest fresh yield （75605 kg·ha−1），WSC （201.4 g·kg-1 DM） and NDF （604. 2 g·kg-1 DM） at the Chengduo site，followed by Longyan No. 3. The highest CP （119.7 g· kg-1 DM） and mold counts （4.12 lg cfu·g-1 FM） were observed in Baiyan No. 2 at the Huangzhong site. Bayou No. 3 produced the highest LAB and yeast counts at Maqin and Chengduo sites. In general，Longyan No. 3 and Longyan No. 5 gave better performance at sites above 3000 m altitude；for sites below 3000 m，the four tested varieties were all found to be suitable for silage production. © 2022 Editorial Office of Acta Prataculturae Sinica. All rights reserved.     

Prevalence and incidence of Newcastle disease and prevalence of Avian Influenza infection of scavenging village chickens in Timor-Lesté

A longitudinal study to monitor prevalence and incidence of antibodies against Newcastle disease (ND) virus and prevalence of antibodies against Avian Influenza (AI) virus in scavenging village chickens was conducted in 20 villages within 4 districts of Timor-Lesté. A total of 3600 blood samples was collected from 1674 individual birds in 300 household chicken flocks during three sampling periods (December 2008-February 2009, March-May 2009, and June-August 2009). The mean interval between household visits was 101.6±1.9 days. None of the birds enrolled in the study was vaccinated against ND or AI. A haemagglutination inhibition (HI) test was used to determine antibody titres against ND virus and a competitive ELISA and HI tests were used to detect antibody against AI virus. The bird-level ND seroprevalence pooled across all samplings (adjusted for clustering by households) was 4.4% (95% CI 3.5-5.2). The bird-level ND seroprevalence in each of the three sampling periods (adjusted for clustering by household) was 3.0% (95% CI 2.0-4.0), 6.6% (95% CI 5.1-8.0) and 3.6 (95% CI 2.5-4.6), respectively. A total of 12.6% individual birds tested ND seropositive at least once over the total study period (95% CI 10.5-14.7). The flock-level ND seroprevalence (at least one bird tested had antibodies against ND virus) pooled across all samplings was 15.9% (95% CI 13.5-18.3). A total of 35.3% flocks had a minimum of one bird being ND seropositive at least once over the study period. The bird-level incidence rate for the period between the first and the second sampling and between the second and the third sampling was 5.6 (95% CI 4.1-7.5) and 0.5 (95% CI 0.5-3.8) per 10,000 bird-years-at-risk, respectively. A total of 1134 serum samples from the last sampling period between June and August 2009 was tested for antibodies against AI virus. Only 4 samples tested Influenza A positive, indicating a bird-level seroprevalence level for Influenza A of 0.4% (CI 0.0-0.7%). These Influenza A positive samples were further tested for HI antibodies against AI virus subtypes of H5N1, H5N3, H7N3 and H9N2, but all tested negative, suggesting that the influenza antibodies in those four birds resulted from exposure to low pathogenic AI viruses of different H subtypes. Our results indicate that village chickens in Timor-Lesté are exposed to ND virus; there was a higher risk of infection during the early months of 2009 than either immediately prior or subsequent to this. No evidence of infection of village chickens with H5, H7 or H9 AI viruses was detected in this study.     

Production benefits of the crossbreeding of indigenous and non-indigenous ducks—growing and laying period body weight and production performance

To evaluate different crosses and purebreds ducks in respect to various economic traits and to estimate different crossbreeding genetic parameters, a 3?×?3 complete diallel cross involving indigenous duck (DD), Khaki Campbell (KK) and White Pekin (WW) were used to produce three purebreds (DD, KK, WW) three crossbreds (DK, DW, KW) and three reciprocals (KD, WD, WK). A total of 609 ducklings produced were reared on deep litter and the females (316 in number) were evaluated for growing and laying period body weight along with the production performance traits. Different crossbreeding genetic parameters were estimated for different traits. All the traits in respect to body weight gain during growing and laying period and different production traits including laying house mortality rate showed significant (p?≤?0.05) difference between different genetic groups. In general, crossbreds perform better than the purebreds for most of the traits studied. General combining ability (GCA), specific combining ability (SCA) and reciprocal effect (RE) were significant (p?≤?0.01) for body weight and production traits. Egg weight showed significant (p?≤?0.01) difference in respect to GCA, SCA and RE for all the ages of measurement except RE for 30th week egg weight. Laying period mortality rate was only significant (p?≤?0.05) for SCA. Most of the crossbreds recorded heterosis rate in desirable direction for majority of the traits. Overall results revealed that the crossbreds perform well in respect to different traits than the purebreds and may be used to take advantage of heterosis. DW performs well in respect to majority of the traits measured and is of importance for commercial exploitation. Further, pure line selection with development of specialised sire and dam line followed by crossing may be of importance to enhance the performances in the crosses.     

Growth and Development of The Kunlun Type of Wild Yak

The observation of body height and weight of 10 captured wild yak shows the body height and weight of the wild yak at three and four months old were similar with that of domestic yak. At their 24 months old, the body height and weight were higher by 26.9 % and 62.5 % than that of the domestic ones. The results indicate that, once adapted to the half-shed and half-grazing conditions, the tamed Kunlun type of wild yak with superior genetics would grow and develop faster than the domestic yak at elder ages.     

Current Status and Enlightenment of Production and Trade of Forage Product in China北大核心CSCD

At present,China's traditional agriculture and animal husbandry has no way to rely on the "fine fodder + straw" feeding model. Only relying on grass and animal husbandry can guarantee China's consumer demand and food safety. However, due to the restraints such as policy, infrastructure, technology, market and organizational factors, the "lacking" status of China's pasture industry is not optimistic. In this paper, we analyze the pasture production, commercial grass production, grass seed production,forage product trade, the import and export volume of different types of pasture products, the current status of pastoral products trading partners and the causes behind it in depth. And concluded that the supply of forage products in China needs to be imported. Imports are growing while exports are generally declining,the pasture trade market is highly concentrated while grassland trading partners are dispersed. Five suggestions are given to provide theoretical guidance for the development of China's pasture industry: increase policy support, promote infrastructure, increase investment in scientific research, strengthen market construction, and develop industrial organizations. © 2019 China Agricultural University. All rights reserved.     

Effect of Discontinuous Administration of β -glucan and Glycyrrhizin on the Growth and Immunity of Pacific White Shrimp Litopenaeus Vannamei

A six-week growth trial was conducted to compare the effects of different feeding strate- gies of dietary immunostimulants on the growth and immunity of white shrimp Litopenaeus vannamei （4.70 ±0.20g）. Shrimps were fed with diet containing glycyrrhizin continuously, containing β -glucan continuously, discontinuously （seven days with diet containing β -gluseven days with diet without -glucan; two days with diet containing β-glucan following five days with diet without -glucan）,     

Effect of diets containing raw and extrusion‐cooked rice bran on growth and efficiency of food utilization of broilers

1. Meat strain chicks were fed on diets containing 600 g rice bran/kg for the 7 to 8 week period required to reach broiler weight.

2. Extrusion cooking of rice bran resulted, in improved chick weight gain and food efficiency for the first two weeks of feeding, but this advantage was lost by the end of the feeding period.

3. Addition of 10 g calcium/kg to the stabilised rice bran diet prevented the decline in performance after two weeks of age, and birds fed on this diet continued to gain at an increasing rate until the end of the experiment.

4. Calcium supplementation of stabilised rice bran diets produced significantly greater gains and superior food utilisation compared to stabilised rice bran diets without added calcium.

5. Calcium supplementation did not affect weight gain of chicks fed on diets containing raw rice bran.

6. Taste panel evaluation of meat from birds fed on diets containing raw rice bran, stabilised rice bran, or no rice bran indicated a significant preference in only one combination tested. Any ‘off flavour could not be related to dietary treatment.     

Effects of oral supplementation with β-carotene on concentrations of β-carotene, vitamin A and α-tocopherol in plasma, colostrum and milk of mares and plasma of their foals and on fertility in mares

In this study, effects of oral β-carotene supplementation to mares (β-carotene group: 1000 mg/day, n = 15; control group: n = 15) from 2 weeks before foaling until 6 weeks thereafter on concentrations of β-carotene, vitamin A and α-tocopherol in plasma, colostrum and milk and plasma of their foals were determined. In addition, effects on fertility were studied. Beta-carotene concentrations increased in plasma and colostrum of β-carotene-supplemented mares compared to control mares (p < 0.05). In mares of both groups, β-carotene concentrations were higher in colostrum than in milk (p < 0.05). In foals, β-carotene concentrations increased with colostrum uptake and were higher in foals born to supplemented mares (p < 0.05; control group: 0.0003 ± 0.0002 μg/ml on day 0, 0.008 ± 0.0023 μg/ml on day 1; β-carotene group: 0.0005 ± 0.0003 μg/ml on day 0, 0.048 ± 0.018 μg/ml on day 1). Concentrations of vitamin A and α-tocopherol were higher in colostrum than in milk (p < 0.05) but did not differ between groups. Concentration of α-tocopherol in plasma of mares decreased over time and in foals, increased markedly within 4 days after birth. All but one mare (control group) showed oestrus within 2 weeks post-partum. Occurrence of oestrus did not differ between groups. More mares of the control group (7/7 vs. 5/12 in the β-carotene group) became pregnant after being bred in first post-partum oestrus (p < 0.05). In conclusion, β-carotene supplementation to mares increased β-carotene concentrations in plasma, colostrum and milk of mares and plasma of their foals but had no positive effects on fertility.     

Effects of nitrogen forms on growth and nitrogen assimilation and utilization of Buchloe dactyloides北大核心CSCD

This research explored the nitrogen (N) uptake preference of Buchloe dactyloides, in order to improve the management of this species over the whole growth cycle. The experiment included two cultivars of B. dactyloides (‘Sundancer’ and ‘Texoka’) and four different N regimes (N0: No N as the control, N1: Urea, N2: Nitrate N, N3: Ammonium N and N4: a 1:1 mixture of nitrate N and ammonium N). The rate of N applied was 500 mg N·kg soil–1 in each case. It was found that total N content, root nitrate reductase (NR) activity, glutamine synthetase (GS) activity and shoot glutamate synthase (GOGAT) activity of B. dactyloides were significantly improved by adding mixed N (P<0.05). Shoot nitrate N content of B. dactyloides was significantly improved by adding nitrate N (P<0.05). Root nitrate N and ammonium N contents of B. dactyloides were significantly improved by adding urea (P<0.05). The shoot ammonium N content and NR activity of B. dactyloides were significantly improved by adding ammonium N (P<0.05). Shoot GS activity of B. dactyloides was significantly reduced by adding ammonium N (P<0.05). Root GOGAT activity of B. dactyloides was significantly reduced by adding nitrate N (P<0.05). Mixed N can better improve the physiological activity and promote the growth of B. dactyloides, but single nitrogen source will inhibit some nitrogen assimilase activity. Based on these results, it is recommended that 1:1 mixed nitrogen should be used as the nitrogen source in the production of B. dactyloides. Where the ammonium:nitrate is not 1:1, urea should be used as the nitrogen source. © 2022 Editorial Office of Acta Prataculturae Sinica. All rights reserved.     

Isolation and Identification of One Strain of Pigeon Paramyxovirus SerotypeⅠ

A pigeon paramyxovirus serotypeⅠ(PPMV-1) isolate was recovered from samples collected from dead pigeons and initial isolation of the virus was performed in 9-day-old specific-pathogen-free (SPF) chicken embryos.The isolate was identified by the hemagglutination (HA) test,hemagglutination-inhibition (HI) assays,RT-PCR,sequencing and analysis of partial of F gene of the virus.The virulence and pathogenicity of the isolate were determined by mean death time (MDT),intracerebral pathogenicity index (ICPI) in 1-day-old chicks and animal regression experiment.The results indicated that one PPMV-1 was isolated from dead pigeon and named as GXP120012.The F gene sequence analysis of PPMV-1 GXP120012 strain showed that the cleavage sites of the virus was ¹¹²R-R-Q-K-R-F¹¹⁷ motif in accordance with characteristic of velogenic strains;The nucleotide sequence homologies of F gene between strain GXP120012 and PPMV-1 reference strain pi/CH/LLN/110713 were high and reached 98.9%.They located the same branch on phylogenetic tree and fell into genotype Ⅵ.The MDT and ICPI values of isolate were 102 h and 0,respectively.The results of animal regression experiment showed that GXP120012 isolate was virulent for pigeons and avirulent for chickens.The present study provided useful material and theoretical basis for the study of molecular epidemiology and prevention and control of Newcastle disease in pigeon in future.     

Effects of Different Sources and Levels of Selenium on Growth Performance and Tissue Selenium Content of 10～11 months Porcupine

The objective of this experiment was to explore the effects of different sources and levels of selenium （Se） on growth performance and tissue Se content of 10～11 months porcupine.Eighty and 10-month-old porcupine with a similar body weight were assigned to 5 groups with 8 replicates of 2 porcupines each.The porcupine were fed a basal diet without Se complementation （control group） or the basal diet adding 0.30 mg/kg Se in the form of sodium selenite （group Ⅰ）,0.20 mg/kg Se in the form of yeast selenium （group Ⅱ）,0.30 mg/kg Se in the form of yeast selenium （group Ⅲ） and 0.30 mg/kg mixed Se （0.15 mg/kg sodium selenite and 0.15 mg/kg yeast selenium）（group Ⅳ）,respectively.The pre-test period lasted for 7 days and the trial period lasted for 45 days.The results showed that compared with the control group,there was no significant differences in the average daily feed intake （ADFI） in each group （P＞0.05）,the average daily gain （ADG） in groups Ⅱ and Ⅲ was significantly increased （P＜0.05）,the feed/gain （F/G） in group Ⅲ was significant decreased （P＜0.05）.Compared with the control group,the concent of Se in liver and muscle of group Ⅲ was extremely significantly increased （P＜0.01）,the content of Se in liver and muscle of groups Ⅱ and Ⅳ was also significantly increased （P＜0.05 or P＜0.01）,and there was no significant difference in group Ⅰ（P＞0.05）.In conclusion,the basal diet supplemented with yeast selenium could improve the growth performance and increase the tissue Se concent in 10～11 months porcupine,and adding 0.30 mg/kg yeast selenium had the best effect.