Resistance of feed enzymes to proteolytic inactivation by rumen microorganisms and gastrointestinal proteases.   总被引：4，自引：0，他引：4  

D P Morgavi  K A Beauchemin  V L Nsereko  L M Rode  T A McAllister  A D Iwaasa  Y Wang  W Z Yang 《Journal of animal science》2001,79(6):1621-1630

Potential feed enzyme additives for ruminants were tested in vitro for their stability to ruminal microbial and gastrointestinal proteolysis. Four commercial preparations from Trichoderma longibrachiatum (A, B, C, and D) and one from an undisclosed source (E) were incubated up to 6 h with ruminal fluid taken from four lactating dairy cows before or 2 h after feeding. The stability of preparation B was also tested in the presence of pepsin at pH 3 and pancreatin at pH 7. Cellulase (EC 3.2.1.4), cellulose 1,4-beta-cellobiosidase (EC 3.2.1.91), beta-glucanase (EC 3.2.1.6), xylanase (EC 3.2.1.8), beta-glucosidase (EC 3.2.1.21), and beta-xylosidase (EC 3.2.1.37) activities were monitored throughout the incubations. Polysaccharidase activities of all enzyme preparations were remarkably stable in ruminal fluid taken after feeding. Ruminal fluid obtained before feeding inactivated the polysaccharidases in preparations B and D to a greater extent than ruminal fluid obtained after feeding. Cellulase and cellulose 1,4-beta-cellobiosidase activities were the least stable, declining (P < 0.05) by 35 and 60% for preparations B and D, respectively. Xylanase activity of preparation D decreased (P < 0.05) by up to 30% after 6 h of incubation, whereas beta-glucanase activity was not affected. The ability to degrade exogenous enzymes also differed among cows (P < 0.05). Pepsin and acid (pH 3.0) did not affect polysaccharidases in preparation B but decreased glycosidase activities by 10 to 15% (P < 0.05) after 1 h of incubation. Pancreatin, at the maximum concentration used, inactivated cellulase, cellulose 1,4-beta-cellobiosidase, and xylanase activities at a rate of 0.55, 1, and 0.45%/min, respectively. beta-Glucosidase and beta-xylosidase activities decreased by 1 and 0.75%/min, respectively. Partial proteolysis of cellulase, cellulose 1,4-beta-cellobiosidase, and xylanase by pancreatin produced a transient increase in activity. This twofold increase for cellulase and fourfold increase for cellulose 1,4-beta-cellobiosidase was directly proportional to pancreatin concentration. These results suggest that the enzyme feed additives tested were stable in the rumen of animals after feeding. Exogenous enzymes are likely to be more susceptible to the host gastrointestinal proteases in the abomasum and intestines than to ruminal proteases. However, exogenous polysaccharidases may survive for a considerable period of time in the small intestine and they probably maintain activity against target substrates in this environment.  相似文献   

Expression of Genes Associated with Apoptosis in the Porcine Corpus Luteum During the Oestrous Cycle     

LM Zorrilla  MA D'Annibale  SE Swing  JE Gadsby 《Reproduction in domestic animals》2013,48(5):755-761

The corpus luteum (CL) of the pig lacks luteolytic sensitivity (LS) to prostaglandin (PG) F‐2α until after day 12 of the oestrous cycle, but the mechanisms underlying this phenomenon are poorly understood. As luteolysis involves apoptosis, we hypothesized that critical apoptotic proteins may be deficient in CLs that lack LS. The specific aim of these studies was to examine mRNA expression and protein levels of apoptosis genes/proteins (BAX/Bax, BCLX/Bcl‐x, CASP3/Caspase‐3, CASP8/Caspase‐8, NFΚB1/NFκB, TP53/p53) in porcine CLs collected at different stages of the oestrous cycle. CLs were collected surgically, mRNA and protein extracted, and expression/levels analyzed by semi‐quantitative (SQ) PCR and Western blots, respectively. At the mRNA expression level, only BAX (maximal on day 4) and TP53 (maximal on day 7) showed significant variations during the oestrous cycle. At the protein level, only Bcl‐x and Caspase‐3 showed significant changes during the cycle; Bcl‐x decreased on day 13 and Caspase‐3 increased on day 13. It is concluded that apoptosis‐associated proteins (i.e. Bcl‐x and Caspase 3) may play a critical role in luteolytic sensitivity in the pig.  相似文献   

Larvicidal activity of synthetic tropane alkaloids against Ascia monuste orseis (Lepidoptera: Pieridae)          下载免费PDF全文

Simone Z Mairink  Luiz CA Barbosa  Eduardo VV Varejão  Elizeu S Farias  Márcio LM Santos  Marcelo C Picanço 《Pest management science》2017,73(10):2048-2053

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Daylight effect on melatonin secretion in adult female guanacos (Lama guanicoe)          下载免费PDF全文

JL Riveros  LM Correa  G Schuler 《Reproduction in domestic animals》2017,52(6):1129-1132

The wild South American camelids developed a strategy of seasonal reproduction during spring and summer with singleton birth. The photoperiod is one of the factors that may modulate this seasonality where light would be translated into a hormonal signal. This study evaluated the influence of changes in daily light intensity on melatonin concentration in captive guanacos under a long‐day photoperiod (16 hr light/8 hr dark; 33 ‘28′S). Mean melatonin concentration was 28.3 ± 20.3 pg/ml, with a maximum of 52.14 ± 17.19 pg/ml at 23:30 and minimum of 14.29 ± 6.64 pg/ml at 08:30 (p < .001). There was a negative association between light intensity and melatonin concentration (r = ?0.57; p < .001). The results indicate that guanacos respond to variation in daily environmental light with a hormonal response and point to a circannual rhythm as a function of the photoperiod.  相似文献   

Demographic and preliminary employment data of the first two graduate cohorts from a rural veterinary school          下载免费PDF全文

JH Hyams  SL Raidal  LM Hayes  J Heller 《Australian veterinary journal》2017,95(4):91-100

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Effects of barley grain processing on the site and extent of digestion of beef feedlot finishing diets   总被引：6，自引：0，他引：6  

Beauchemin KA  Yang WZ  Rode LM 《Journal of animal science》2001,79(7):1925-1936

Effects of extent of barley rolling on chewing activities, ruminal fermentation, and site and extent of digestion were evaluated for feedlot finishing cattle diets in a 4 x 4 Latin square design. Four Jersey steers (452 kg), cannulated in the rumen and duodenum, were used. Barley grain was temper-rolled to four extents: coarse, medium, medium-flat, and flat, which were expressed as processing index (PI, volume weight of barley after processing expressed as a percentage of its volume weight before processing, DM basis) and equivalent to 82, 75, 70, and 65%, respectively. Diets consisted of 9.7% barley silage, 86% temper-rolled barley, and 4.3% other ingredients (DM basis). Steers were offered ad libitum access to a total mixed ration once daily. Dry matter intake was not affected (P > 0.15) by PI of barley. Digestibility of OM in the rumen and in the total tract were numerically lower (P = 0.13) for steers fed coarsely rolled barley than for steers fed more extensively processed barley. Digestibility of starch in the total tract was linearly increased (P = 0.02) with grain processing, but NDF digestion was not affected by processing (P > 0.15). Digestibility of CP did not differ in the rumen but tended (P = 0.08) to increase in the total tract with increased processing of barley. Flow of microbial nitrogen to the duodenum was approximately one-third lower (linear effect, P = 0.06) for steers fed coarsely rolled barley than for steers fed further rolled barley. Increased grain processing tended to decrease (linear effect, P = 0.08) rumination time without affecting eating time. These results indicate that optimal degree of rolling for barley fed to feedlot cattle corresponded to a PI of 75% or lower. Coarsely rolled barley is not recommended because it resulted in the lowest digestibility and lowest microbial protein synthesis. Processing barley to attain a PI less than 75% resulted in marginal improvements in feed digestion, but rumination time decreased, which could lead to problems associated with acidosis if lower-fiber diets are used.  相似文献   

Ivermectin toxicosis in a neonatal foal   总被引：1，自引：0，他引：1  

LM GODBER †  FJ DERKSEN  JF WILLIAMS†  B. MAHMOUD§ 《Australian veterinary journal》1995,72(5):191-192

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Bovine citrullinaemia traced to the sire of Linmack Kriss King   总被引：1，自引：0，他引：1  

PJ HEALY  JA DENNIS  LM CAMILLERI  JL ROBINSON  AL STELL  RD SHANKS 《Australian veterinary journal》1991,68(4):155-155

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Selection of a sterilization method for the study of cereal grain digestion     

T A McAllister  L M Rode  K J Cheng  C W Forsberg 《Journal of animal science》1991,69(7):3039-3043

Experiments were initiated to select a sterilization method(s) that minimizes alterations in the digestive properties of cereal grains and, thus, would be suitable for the study of cereal grain digestion by pure cultures of ruminal bacteria. The following five treatments were examined: unsterilized (U), autoclaving with buffer (AB), autoclaving without buffer (AD), ethylene oxide (E), and gamma irradiation (I). Solubility of DM, starch, and CP was determined by soaking grain in buffer for 1 h followed by filtration through Whatman #54 filter paper. Ground corn and wheat from each treatment were placed in vials with a 1:1 mixture of Bryant's medium and ruminal inoculum. Vials were incubated for 4, 8, 12, 24, and 48 h and analyzed for starch content. Bacterial growth was not evident in sterilized, uninoculated samples. The AD treatment decreased the disappearance of CP in wheat and corn, whereas AB caused an increase in the disappearance of DM, CP, and starch in wheat (P less than .001) compared with U. Rates of microbial starch digestion for corn were 1.3, 1.5, 3.3, 14.7, and 3.5%/h and for wheat were 1.3, 3.4, 4.6, 17.1, and 4.6%/h for AD, E, I, AB, and U, respectively. Contrasts indicated that AD and AB differed (P less than .001) from U for both corn and wheat. It is likely that gelatinization of cereal starch enhanced microbial starch digestion in AB and the formation of Maillard products reduced starch digestion in AD. Corn and wheat sterilized with E or I had digestive properties that closely resembled those of U grain, and either sterilization method was suitable for studying cereal grain digestion.  相似文献   

Effects of ketamine, xylazine, and a combination of ketamine and xylazine in Pekin ducks     

J W Ludders  J Rode  G S Mitchell  E V Nordheim 《American journal of veterinary research》1989,50(2):245-249

Effects of ketamine, xylazine, and a combination of ketamine and xylazine were studied in 12 male Pekin ducks (7 to 12 weeks old; mean [+/- SD] body weight, 3.1 +/- 0.3 kg). After venous and arterial catheterization and fixation of a temperature probe in the cloaca, each awake duck was confined, but not restrained, in an open box in a dimly lit room. Blood pressure and lead-II ECG were recorded. Three arterial blood samples were collected every 15 minutes over a 45-minute period (control period) and were analyzed for pHa, PaCO2 and PaO2. After the control period, each duck was assigned at random to 1 of 3 drug groups: (1) ketamine (KET; 20 mg/kg of body weight, IV), (2) xylazine (XYL; 1 mg/kg, IV), and (3) KET + XYL (KET 20 mg/kg and XYL, 1 mg/kg; IV). Measurements were made at 1, 5, 10, 15, 30, 45, 60, and 90 minutes after drug administration. All ducks survived the drug study. Cloacal temperature was significantly (P less than or equal to 0.05) increased above control cloacal temperature at 90 minutes after the administration of ketamine, and from 10 through 90 minutes after administration of ketamine plus xylazine. In ducks of the KET group, pHa, PaCO2, and PaO2, remained unchanged after administration of the drug. In ducks of the XYL group, pHa and PaO2 decreased significantly (P less than or equal to 0.05) from control values for all time points up to and including 15 minutes after drug administration.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献