Effect of exogenous glucagon and free fatty acids on gluconeogenesis in fasting neonatal pigs

Thirty-two pigs (1 d old) were used to determine if exogenous glucagon and(or) free fatty acids (FFA oleic acid) would enhance gluconeogenesis and glucose homeostasis during fasting. Pigs were acquired at birth, fitted with an indwelling arterial cannula (via umbilicus) and fasted 24 h to deplete liver glycogen. A jugular cannula was inserted nonsurgically 8 to 10 h before initiation of a primed-continuous infusion consisting of control (excipient), glucagon (Glu), oleic acid (FFA), or both glucagon and oleic acid (Glu-FFA). Plasma Glu averaged 395 pg/ml preinfusion and was similar across treatments. The concentration increased fivefold (P less than .05) by 80 min for Glu and Glu-FFA pigs and remained constant thereafter (160 min: 2,379, 2,258 pg/ml; 240 min: 2,355, 2,274 pg/ml, respectively). Glucagon infusion did not alter plasma glucose after 240 min of infusion (control, 50 vs Glu, 51 mg/dl); however, Glu-FFA effected an increase (60 mg/dl, P less than .10). In contrast, pigs infused with FFA alone had a lower glucose concentration (40 mg/dl, P less than .10). Rate of glucose synthesis was determined using liver slices, acquired immediately postinfusion, with alanine and lactate as substrate (7.5 mM). The rate of synthesis was not altered by Glu or Glu-FFA infusion (2.91, 2.43 mumol glucose X g-1 X h-1 vs 2.91 for control). In contrast, exogenous FFA reduced synthesis to 1.85 mumol glucose X g-1 X h-1 (P less than .05) with lactate as substrate. It appears that Glu is not the primary factor limiting gluconeogenesis in fasting newborn pigs.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of von Willebrand Factor During Pregnancy,Lactation and Oestrous Cycle in Bitches Affected and Unaffected by von Willebrand Disease

Plasmatic concentrations of von Willebrand Factor (vWF) increase during pregnancy in humans and dogs; however the mechanism of such increase is still not well defined. The aims of this study were: (i) to evaluate changes in vWF concentration during pregnancy and during the subsequent oestrous cycle in bitches affected and unaffected by von Willebrand Disease (vWD); (ii) to correlate the vWF levels and cortisol levels in both groups. Seven vWD affected (GI) and nine unaffected (GII) bitches were used. The animals were assessed during pregnancy, parturition, lactation and non‐gestational oestrous cycle in 11 moments (Pregnancy 1, Pregnancy 2, Parturition, Lactation 1, Lactation 2, Lactation 3, Anestrus, Proestrus, Oestrus, Diestrus 1, and Diestrus 2). The following tests were performed; measurement of von Willebrand factor antigen (vWF:Ag), albumin and cortisol. In both groups, vWF concentration remained stable during the non‐gestational oestrous cycle, but increased during pregnancy, with the highest value observed at parturition. Increases of 70% and 124% in vWF were seen in GI and GII, respectively, compared to anestrus. No correlation was found between vWF and cortisol. Values of vWF:Ag changed during pregnancy, with a peak at parturition, both in vWD affected and unaffected animals. Values of vWF were not altered in the different phases of the oestrous cycle following pregnancy in both groups. Evaluation of vWF during pregnancy can cause false negative results for vWD, but assessment can be performed at any point in the oestrous cycle of non‐pregnant bitches.     

Report on the analyses of mAb reactive with porcine CD8 for the second international swine CD workshop

Based on an analysis of their reactivity with porcine peripheral blood lymphocytes (PBL), only three of the 57 mAbs assigned to the T cell/activation marker group were grouped into cluster T9 along with the two wCD8 workshop standard mAbs 76-2-11 (CD8a) and 11/295/33 (CD8b). Their placement was verified through the use of two-color cytofluorometry which established that all three mAbs (STH101, #090; UCP1H12-2, #139; and PG164A, #051) bind exclusively to CD8⁺ cells. Moreover, like the CD8 standard mAbs, these three mAbs reacted with two proteins with a MW of 33 and 35 kDa from lymphocyte lysates and were, thus, given the wCD8 designation. Because the mAb STH101 inhibited the binding of mAb 76-2-11 but not of 11/295/33, it was given the wCD8a designation. The reactivity of the other two new mAbs in the T9 cluster with the various subsets of CD8⁺ lymphocytes were distinct from that of the other members in this cluster including the standards. Although the characteristic porcine CD8 staining pattern consisting of CD8^low and CD8^high cells was obtained with the mAb UCP1H12-2, a wider gap between the fluorescence intensity of the CD8^low and CD8^high lymphocytes was observed. In contrast, the mAb PG164A, not only exclusively reacted with CD4⁻/CD8^high lymphocytes, but it also failed to recognize CD4/CD8 double positive lymphocytes. It was concluded that this mAb is specific for a previously unrecognized CD8 epitope, and was, thus, given the wCD8c designation. A very similar reactivity pattern to that of PG164A was observed for two other mAbs (STH106, #094; and SwNL554.1, #009). Although these two mAbs were not originally positioned in the T cell subgroup because of their reactivity and their ability to inhibit the binding of PG164A, they were given the wCD8c designation. Overall, five new wCD8 mAbs were identified. Although the molecular basis for the differences in PBL recognition by these mAbs is not yet understood, they will be important in defining the role of CD8⁺ lymphocyte subsets in health and disease.     

增加哺乳母猪日粮中L-赖氨酸的添加量

在低水平豆粕型母猪哺乳期饲料中添加合成赖氨酸以平衡日粮的营养水平,不会对母猪当前和以后的生产性能产生负面影响,虽然合成氨基酸的成本增加了,但整体生产成本能够下降。     

The Effect of a Chronic Stressor, Lameness, on Detailed Sexual Behaviour and Hormonal Profiles in Milk and Plasma of Dairy Cattle

The objectives of the present study were to quantify the effects of a biological chronic stressor (lameness) on the duration and frequency of different oestrous behaviours in parallel with milk hormone profiles. Dairy cows 51.8 ± 1.4 days postpartum (n = 59), including 18 non‐lame control cows, were scored for lameness and closely observed for signs of oestrus having had their follicular phases synchronized by administration of gonadotrophin‐releasing‐hormone (GnRH) followed by prostaglandin F_2α (PG) 7 days later. Lameness shortened the period when herd‐mates attempted to mount the lame cows (1.83 ± 0.69 h vs 5.20 ± 1.53 h; p = 0.042) but did not affect the overall duration of total behaviours (lame 12.3 ± 1.3 h vs non‐lame 15.2 ± 1.3 h). Lameness also lowered the intensity of oestrus [1417 ± 206 points (n = 18) vs 2260 ± 307 points (n = 15); p = 0.029]. Throughout the synchronized oestrous period, lame cows mounted the rear of herd‐mates less frequently (p = 0.020) and tended to chin rest less (p = 0.075). Around the period of maximum oestrous intensity, lameness also diminished the proportion of cows mounting the rear of another cow and chin resting (p = 0.048, p = 0.037, respectively). Furthermore, lame cows had lower progesterone values during the 6 days before oestrous (p ≤ 0.05). Fewer lame cows were observed in oestrus following PG (non‐lame 83%, lame 53%; p = 0.030); however, if prior progesterone concentrations were elevated, lame cows were just as likely to be observed in oestrus. In conclusion, following endogenous progesterone exposure, lameness shortens the period when herd‐mates attempt to mount lame cows but does not affect the incidence of oestrous. However, lame cows are mounted less frequently and express oestrus of lower intensity. This is associated with lower progesterone prior to oestrus but not with abnormal oestradiol or cortisol profiles in daily milk samples.     

Follicular Dynamics, Ovulation and Conception Rates in Bitches

Real-time ultrasound imaging was used in a clinical study to estimate the number of follicles of different sizes, ovulation and conception rates, and to study follicle dynamics following oestrus-induction of bitches.
Follicles were identified during late anoestrus (between 100 and 60 days prior to the pre-ovulatory LH surge) and there appeared to be a shift in the population from small follicles (1–3 mm in diameter) to large follicles (>4 mm diameter) approximately 2 days prior to the LH surge. Corpora lutea could be reliably identified although the majority were cavitated. High ovulation rates (97–100%) and pregnant rates (86–100%) were detected, and although the conception rate was approximately 70% it varied between 8 and 92%. Within the narrow range of the clinical population studied there were trends relating age to reproduction performance. Oestrus induction with a gonadotrophin regime appeared to result in large numbers of small follicles that did not ovulate, whilst when using cabergoline the number of small and large follicels and the number of copora lutea were similar to those of control cycles.     

Poind Soil pH Measurement

Soil pH often is measured in samples from the bottoms of aquaculture ponds. Several different techniques for soil pH are used. This study considered the differences in pH obtained by the different methods and determined which methods appeared most useful. Dual electrodes (indicating and reference) and a single‐probe combination electrode gave similar pH values when inserted into 1:1 mixtures of dry soil and distilled water. There were slight differences in pH between readings with dual and combination electrodes when the dual electrodes were arranged with the indicating electrode in the sediment phase and the reference electrode in the supernatant phase of the mixture. The two‐phase method with the dual electrode does not appear warranted because of greater difficulty in making measurements. Dry soil: distilled water ratios of 1:2.5, 1:5, and 1:10 had progressively greater pH readings than obtained at a 1:1 ratio. Measurements made in 0.01 M CaCl₂ and 1.0 M KCl had much different values than those made in distilled water. Higher pH resulted when pH was measured without stirring or in filtrates of soil‐water mixtures. A 20‐min period of intermittent stirring before making measurements was necessary for a stable pH value. Particle size did not influence pH in aliquots passing 0.053 to 2.36‐mm sieves. Drying temperature had a strong influence on pH, and measurements made on samples dried at 40 to 60 C are probably most reliable. Measurements of in situ pH in wet soil with standard pH electrode or a portable acidity tester differed greatly from those made in 1:1 dry soil to distilled water mixtures. Pond bottom soil pH measurement should be standardized. Based on findings of this study, the following method is suggested: dry soil at 60 C in a forced‐draft oven; pulverize soil to pass a 2‐mm sieve; mix soil and distilled water in a 1:1 ratio (weight: volume); stir intermittently with glass rod for 30 min; insert dual electrodes or a combination electrode into the mixture; measure pH while stirring.     

Field measurements of CO2 enhancement and climate change in natural vegetation

It is generally assumed that healthy, natural ecosystems have the potential to sequester carbon under favorable environmental conditions. There is also evidence that CO₂ acts as a plant fertilizer. It is of interest to know if these assumptions are valid and how natural systems might respond under future scenarios of CO₂ increase and possible climate changes. Few measurements of the effects of CO₂ and global climate change have been made on “natural” ecosystems under realistic field conditions. Most measurements have been conducted in the synthetic environments of totally controlled greenhouses and growth chambers. Several lines of evidence indicate that controlled environment studies using plants growing in pots induce experimental artifacts that reduce confidence in the use of results for prediction of future global responses. Open top chambers are being used in several autecological field studies in an attempt to obtain more realistic field environments. A few field microcosm studies have been completed and a system for the free air release of CO₂ has been applied in cotton fields. Unfortunately, the requirement of large amounts of CO₂ and financial restrictions have precluded the initiation of larger scale field studies in natural vegetation. This paper lists and summarizes the best field studies available but draws heavily on studies from artificial environments and conditions in an attempt to summarize knowledge of global environmental change on forests and other non-agricultural ecosystems. Finally the paper concludes that there is a need for the development and application of equipment for field measurements in several representative natural ecosystems and makes specific recommendation of the creation of a tropical research center.