Sequential feeding with variations in energy and protein levels improves gait score in meat-type chickens

Feeding broilers by alternating different diets for 1 or 2 days is known as sequential feeding, and it possibly reduces leg problems since it slows down early growth and may enhance general activity. The present study compared continuous feeding with a standard diet (C: metabolisable energy = 12.55 MJ/kg, crude protein = 190 g/kg) with alternations of a high-energy/low-protein diet (E+P-:+7% ME; -20% CP) and a low-energy/high-protein diet (E-P+: -7% ME,+20% CP) and investigated its effects on growth, behaviour and gait score in 352 male Ross broiler chickens. Sequential feeding was carried out during ten 48-h sequential-feeding cycles from 8 to 28 days of age. Three treatments were compared: complete diet (C) and two alternations of diets varying in protein and energy contents (S1: E+P- followed by E-P+; and S2: E-P+ followed by E+P-). Chickens received the same feed during the starter and finisher periods (0 to 7 and 29 to 38 days of age). Body weight (BW), feed intake, general activity and gait score, bone quality and carcass conformation were measured to evaluate leg condition and general performance. Sequential feeding significantly reduced BW at 28 days of age (S1: -9.1%; S2: -3.7%/C group; P < 0.05) and S1 were lighter than S2. In both sequential groups, time spent standing increased (C: 28%; S1:33%; S2: 35%; P < 0.05) and leg abnormalities decreased (mean gait score: C: 2.61; S1: 2.45; S2: 2.38; P < 0.02). This improvement was not related to changes in bone quality. BW at slaughter was impaired in Group S1 only, and the feed conversion ratio throughout the rearing period was not significantly impaired by sequential feeding. However, abdominal fat was higher in the S2 group. Sequential feeding using diets varying in energy and crude protein can be a useful method of reducing leg problems in broilers since it improves gait score without impairing growth performance when used as early as 8 days of age and up to not less than 8 days before slaughter in order to compensate for reduced growth. This improvement can be explained by reduced early growth and enhanced motor activity. However, it appears that the low-energy diet should be given first in order to avoid a reduction in BW at slaughter.     

Plant growth-promoting rhizobacteria systemically protect Arabidopsis thaliana against Cucumber mosaic virus by a salicylic acid and NPR1-independent and jasmonic acid-dependent signaling pathway

Arabidopsis thaliana ecotype Columbia plants (Col-0) treated with plant growth-promoting rhizobacteria (PGPR) Serattia marcescens strain 90-166 and Bacillus pumilus strain SE34 had significantly reduced symptom severity by Cucumber mosaic virus (CMV). In some cases, CMV accumulation was also significantly reduced in systemically infected leaves. The signal transduction pathway(s) associated with induced resistance against CMV by strain 90-166 was determined using mutant strains and transgenic and mutant Arabidopsis lines. NahG plants treated with strains 90-166 and SE34 had reduced symptom severity indicating that the resistance did not require salicylic acid (SA). Strain 90-166 naturally produces SA under iron-limited conditions. Col-0 and NahG plants treated with the SA-deficient mutant, 90-166-1441, had significantly reduced CMV symptom severity with reduced virus accumulation in Col-0 plants. Another PGPR mutant, 90-166-2882, caused reduced disease severity in Col-0 and NahG plants. In a time course study, strain 90-166 reduced virus accumulation at 7 but not at 14 and 21 days post-inoculation (dpi) on the non-inoculated leaves of Col-0 plants. NahG and npr1-1 plants treated with strain 90-166 had reduced amounts of virus at 7 and 14 dpi but not at 21 dpi. In contrast, no decrease in CMV accumulation occurred in strain 90-166-treated fad3-2 fad7-2 fad8 plants. These data indicate that the protection of Arabidopsis against CMV by strain 90-166 follows a signaling pathway for virus protection that is independent of SA and NPR1, but dependent on jasmonic acid.     

Effect of creatine phosphate supplementation on anaerobic working capacity and body weight after two and six days of loading in men and women

The purpose of this study was to determine the effects of 2 and 6 days of creatine phosphate loading on anaerobic working capacity (AWC) and body weight (BW) in men and women. Sixty-one men (n = 31) and women (n = 30) randomly received 1 of 3 treatments (4 x 5 g.d(-1) x 6 days) using a double blind design: (a) 18 g dextrose as placebo (PL); (b) 5.0 g Cr + 20 g dextrose (Cr); or (c) 5.0 g Cr + 18 g dextrose + 4 g of sodium and potassium phosphates (CrP). AWC was determined at baseline and following 2 and 6 days of supplementation using the Critical Power Test. BW increased significantly over time, and the mean value for the men was significantly greater compared to that for women, but there were no interactions (p > 0.05). There were gender-specific responses for AWC expressed in both absolute values (kJ) and relative to BW (kJ. kg(-1)), with the women demonstrating no significant interactions. For the men, CrP loading significantly increased AWC following 2 days (23.8%) and 6 days (49.8%) of supplementation vs. PL (kJ and kJ.kg(-1)). Cr supplementation increased AWC 13-15% in both genders compared to PL (1.1%- 3.0% decline); although this result was not statistically significant, it may have some practical significance.     

Observations on thermoregulatory ontogeny of mink (Mustela vison)

(1) We measured cooling rate for neonatal mink during a 10min coldroom (3.9 degrees C) exposure and subsequent warming rate during a 20min incubator (37.2 degrees C) exposure, the behaviour of the kits and the changes in their pelage between 1 and 46d of age, in an attempt to monitor the ontogeny of their thermoregulatory capacity. (2) Body weight of the 1d old kits averaged only 12.8+/-2.3g (n=4), but they gained weight rapidly reaching 226.1+/-28.3g (males, n=4) and 207.6+/-16.1g (females, n=4) at 30-31d of age, and 562.3+/-43.2g (males, n=3) and 435.7+/-35.5g (females, n=4) at 45-46d of age. (3) Body cooling rate (C(rate) ( degrees C/min); n=80) was affected by the age (between 1 and 31d), BW, initial rectal temperature (T(r0)), and sex of the kits, in addition to their body posture (P(cold), 1=extended, 2=curled-up) during coldroom exposure. C(rate) ( degrees C/min)=-0.34-0.02age-0.002BW+0.05T(r0)-0.06sex-0.20P(cold) (R(2)=0.75). (4) Body warming rate (W(rate) ( degrees C/min); n=80) was influenced by the age(2) and rectal temperature of the kit after the coldroom exposure (T(r10)). W(rate)( degrees C/min)=1.24+0.0002age(2)-0.04T(r10) (R(2)=0.76). (5) Kit fur fibre length increased from 5.45+/-0.63mm (males, n=2) and 6.20+/-0.20mm (females, n=3) at 22-23d of age to 9.43+/-1.44mm (males, n=4) and 8.70+/-1.89mm (females, n=4) at 30-31d of age, and to 12.93+/-0.47mm (males, n=3) and 11.38+/-0.41mm (females, n=4) at 45-46d of age, the growth averaging about 0.26mm per day. (6) Under normal circumstances newborn mink kits are hypothermic.Their thermoregulation develops only gradually and is dependent on increase in body mass, insulation and behavioural thermoregulation. Their strategy of survival is based on the ability to withstand hypothermia and on the nutrition and warmth provided by the dam.     

Effect of thirty days of creatine supplementation with phosphate salts on anaerobic working capacity and body weight in men

The purpose of this study was to determine the effect of 30 days of single-dose creatine supplementation with phosphate salts (CPS) on body weight (BW) and anaerobic working capacity (AWC) in men. Using a double-blind design, 32 men randomly received 1 serving of either CPS (5 g Cr + 4 g phosphate) (n = 17) or 20 g of dextrose as placebo (PL) (n = 15) for 30 days. AWC determined from the Critical Power Test and BW were measured at baseline, 10 days, 20 days, 30 days, and 10 days post-supplementation. Results (2 x 5 ANOVA) showed no significant differences between groups for AWC at any time point; however, BW was significantly increased at 10 days in the CPS group (1.0 kg) vs. PL (0.0 kg), and remained elevated for the duration of the study. These findings suggest that a single 5 g x d(-1) dose of CPS for 30 days increases BW but is not effective for increasing AWC in men.     

刺五加提取物对早期断奶仔猪生长性能和抗氧化能力的影响(英文)

为了研究刺五加提取物(ASE)替代抗生素降低仔猪早期断奶应激的效果及其作用机制.刺五加提取物多糖、黄酮和有机酸含量分别为2.94,0.19和1.04%;试验选用96头体重相近的21日龄杜×长×大断奶仔猪,按体重和性别随机分为3个处理,每个处理4个重复,分别饲喂基础日粮、添加ASE日粮(1 g/kg)和添加抗生素日粮(0.04%杆菌肽锌+0.03%咔吧氧).试验期为14 d,观察仔猪生长性能,测定7和14 d血清抗氧化指标等的变化.与基础日粮组相比,ASE和抗生素分别提高了仔猪日增重(ADG)16.81(P＞0.05)和24.66%(P＜0.05),均显著降低了料肉比(F/G)(P＜0.05);与抗生素组差异不显著.ASE和抗生素均可提高血清SOD水平;但是,在抗生素组中,第14 d仔猪血清SOD有降低的趋势(从147.96±15.88 U/mL降低至125.68±14.26U/mL).ASE有提高断奶后第7和14 d血清GSH含量的趋势(P=0.235和0.211),并极显著降低了7和14 d血清MDA水平(P＜0.05).结果表明,ASE可促进仔猪生长,提高机体抗氧化能力,在一定程度上可以替代抗生素.     

Effect of the thyroid on faecal shedding of E. coli O157:H7 and Escherichia coli in naturally infected yearling beef cattle

AIMS: To determine if thyroid function affects faecal shedding of Escherichia coli O157:H7. METHODS AND RESULTS: Eight yearling cattle (n = 4 per treatment group), previously identified as shedding E. coli O157:H7, received either 0 or 10 mg 6-N-propyl-2-thiouracil (PTU) kg(-1) BW day(-1) for 14 days to reduce serum concentrations of the thyroid hormones, T(3) and T(4). Animals were monitored daily for changes in faecal shedding of E. coli O157:H7 and E. coli (EC) for the 14-day treatment period and an additional 7 days post-treatment. Body weight was measured weekly and serum concentrations of T(3) and T(4) were determined every 3 days. No differences in faecal shedding of E. coli O157:H7 were observed during the 14-day treatment period. However, compared with control animals, a greater percentage of PTU-treated cattle ejected E. coli O157:H7 on day 16 (100 vs 25%) and 18 (75 vs 0%) of the post-treatment period. Serum T(3) was lower in PTU-treated cattle during the 14-day treatment period and greater on day 18 of the post-treatment period. CONCLUSION: Cattle with chemically altered thyroid hormones had similar shedding patterns of faecal E. coli O157:H7 and EC during the 14-day treatment period. However, faecal shedding of E. coli O157:H7 tended to be greater, and serum concentrations of T(3), were greater for PTU-treated cattle immediately following the termination of PTU treatment. SIGNIFICANCE AND IMPACT OF THE STUDY: Short-term chemical inhibition of thyroid hormones had minimal effects on faecal shedding of E. coli O157:H7 in naturally infected cattle. However, a hyperthyroid state as observed postdosing might play a role in the seasonal shedding of E. coli O157:H7 in cattle.     

IGF-I and IGF binding protein-3 levels during initial GH dosage step-up are indicators of GH sensitivity in GH-deficient children and short children born small for gestational age

BACKGROUND: A stepwise increment of the GH dose is an approach aimed at avoiding adverse events. We investigated GH sensitivity by studying IGF-I and IGFBP-3 concentrations during the initial phase of GH treatment. METHODS: Our investigation was part of the regular follow-up of prepubertal children with GH deficiency (GHD) (n = 31) and small for gestational age (SGA) (n = 23). Dosage was increased in three steps: one-third at the start, two-thirds after 14 days, and the full dose after 28 days (full dose: GHD = 28 microg/kg body weight (BW)/day; SGA = 60 microg/kg BW/day). Blood samples were taken on days 0, 14 and 28, as well as in conjunction with anthropometrical examinations after 3, 6 and 12 months. IGF-I and IGFBP-3 were measured by means of published in-house RIAs and age-related references were used to calculate standard deviation scores (SDS). Height velocity (cm/year) and Delta HT SDS were taken as growth response parameters. RESULTS: Before GH treatment (GHD vs. SGA; median and p values): age (years) (6.6 vs. 6.0; n.s.), HT SDS (-2.6 vs. -3.2; p < 0.05); GH amount after stepping up (mug/kg BW/day) (28 vs. 60; p < 0.01); BW SDS (-0.5 vs. -2.9; p < 0.01); max. GH stimulated (microg/l) (5.6 vs. 10.8; p < 0.01); IGF-I SDS (-3.5 vs. -1.8; p < 0.01); IGFBP-3 SDS (-2.0 vs. 0.8; p < 0.01). After 1 year of GH therapy: HT velocity (cm/year) (9.8 vs. 9.6; n.s.), Delta HT SDS (0.9 vs. 0.9; n.s.); WT velocity (kg/year) (3.3 vs. 3.5; n.s.). Our results show that changes in growth similar to GHD could be induced in SGA by a dosage that was twice as high as the replacement dose given in GHD. GH dose and HT velocity did not correlate in both groups. IGF-I and IGFBP-3 increased as follows in GHD and SGA during stepping up of the dosage (ng/ml, GHD vs. SGA): at start, 54 vs. 89; at day 14, 78 vs. 132; at day 28, 90 vs. 167; at 3 months, 118 vs. 218. There was the same relationship between dose levels and absolute IGF-I concentrations in both groups. In terms of IGF-I SDS, the dose-response curve in SGA showed a shift to the right in comparison to GHD, thus indicating lower sensitivity to GH. The dynamics of IGF-I and IGFBP-3 differed, as IGFBP-3 peaked earlier (on day 28). In GHD, IGF-I SDS at 3 months was -0.7 vs. +0.9 in SGA. Near-identical levels were found for Delta IGF-I SDS and IGFBP-3 SDS above basal levels for each time-point investigated. First year HT velocity in GHD correlated negatively with basal IGF-I SDS (R(2) = 0.33; p <0.001) and basal IGFBP-3 (R(2) = 0.17; p <0.05) but did not correlate with the IGF-I increment during the 0- to 3-month period. Conversely, first year HT velocity correlated (+) in SGA with the IGF SDS increment during the 0- to 3-month period (R(2) = 0.26; p = <0.05). Height velocity in SGA, however, correlated neither with basal IGF-I and IGFBP-3 nor with the 0- to 3-month increments of IGFBP-3 SDS. CONCLUSIONS: IGFs increase during initial GH therapy, thus raising questions about short-term IGF generation tests. (I) In terms of IGF generation, substantially lower sensitivity to GH was observable in SGA. (II) Higher GH sensitivity during first year catch-up growth is associated with GHD, but in SGA it is attributable to increases in IGF. A wider range of GH dosages needs to be explored in order to gain further insight into the relationship between GH dose, IGF levels, and growth. Monitoring IGFs is a practical means for exploring GH sensitivity during dosage stepping up.     

Impaired angiogenesis in aging is associated with alterations in vessel density, matrix composition, inflammatory response, and growth factor expression.

It is generally accepted that angiogenesis is delayed in aging. To define the effects of age on the neovascular response, polyvinyl alcohol sponges were implanted SC in young (6-8 months old, n=11) and aged (23-25 months old, n=13) mice and sampled at 14 and 19 days. Angiogenic invasion was significantly delayed in aged mice at 14d relative to young at 14d (% area of invasion 9.0 +/- 3.7 vs 19.0 +/- 5.6; p=0.02). Although microvessel morphology and basement membrane composition were similar between the age groups, a significant decrease in capillary density was noted in aged tissues at 14d (7.5 +/- 4.1) and 19d (12.1 +/- 2.8) relative to young at 14d (18.7 +/- 2.3) (p<0.01 A14d vs Y14d). In comparison to young at 14d, the inflammatory response was decreased by 43 +/- 2.9% and 36 +/- 7.8% in aged mice at 14d and 19d, respectively. Tissues of aged mice showed less newly deposited collagen. There was a lack of expression of transforming growth factor-beta1 (TGF-beta1) and vascular endothelial growth factor (VEGF) in aged mice at 14d (0.63 +/- 0.3) and 19d (1.14 +/- 0.5) vs young at 14d (1.92 +/- 0.5) (p< or =0.01 A14d vs Y14d for VEGF). However, similar production of VEGF receptor2 was observed. In contrast to young mice, there was significantly increased expression of thrombospondin-2 (TSP-2) in aged mice from 14d (14.6 x 10(3) +/- 7.3 x 10(3)) to 19d (34.9 x 10(3) +/- 17 x 10(3)). We conclude that angiogenesis in aging is not merely delayed, but is altered due to multiple impairments.     

Comparison of performance,health and welfare aspects between commercially housed hatchery-hatched and on-farm hatched broiler flocks

On-farm hatching systems for broiler chicks are increasingly used in practice. We studied whether or not performance, health and welfare aspects differed between commercial flocks hatched on-farm or in a hatchery (control). In two successive production cycles on seven farms, a total of 16 on-farm hatched flocks were paired to 16 control flocks, housed at the same farm. Paired flocks originated from the same batch of eggs and were subjected to similar on-farm management. On-farm hatched and control flocks only differed with respect to hatching conditions, with on-farm hatched flocks not being exposed to, for example, chick handling, post-hatch feed and water deprivation and transport, in contrast to control flocks that were subjected to standard hatchery procedures, subsequently transported and placed in the poultry house. Day-old chick quality (navel and hock scores), 1^st week mortality, total mortality, BW at day (d) 0, d7 and at depopulation, and (total) feed conversion ratio were determined. Prevalence of footpad dermatitis, hock burn, breast discoloration/blisters and cleanliness, litter quality and gait score were determined at d21 of age and around depopulation (d39 on average). Gross pathology and gut morphology were examined at depopulation age in a sample of birds of five flocks per treatment. On-farm hatching resulted in a higher BW at d0 (Δ=5.4 g) and d7 (Δ=11.5 g) (P<0.001), but day-old chick quality as measured by navel (P=0.003) and hock (P=0.01) quality was worse for on-farm hatched compared to control birds. Body weight, 1^st week and total mortality, and feed conversion ratio at slaughter age were similar for both on-farm hatched and control flocks. On-farm hatched flocks had less footpad dermatitis (P=0.05), which indicated a better welfare. This was likely related to a tendency for better litter quality in on-farm hatched flocks at 21 days of age in comparison to control flocks (P=0.08). No major differences in gross pathology or in intestinal morphology at depopulation age were found between treatments. In conclusion, on-farm hatching resulted in better 1^st week broiler performance and better welfare compared to conventional hatching in a hatchery.     

Evaluation of microbially enhanced soybean meal as an alternative to fishmeal in weaned pig diets

An experimental, microbially enhanced soybean product (MEPRO) was evaluated as a replacement for fishmeal (FM). Assessment of feedstuffs should include estimation of digestibility as well as pig performance and in combination with dietary additives. Digestibility values determined in growing pigs may not apply to nursery pigs; thus, standardized ileal digestibility (SID) of amino acids (AA) in MEPRO and FM were determined using 30±1.6 kg BW ileal-cannulated barrows (n=6) and 9.8±1.2 kg BW barrows (n=37; serial slaughter). Experimental diets included MEPRO, FM and nitrogen free where FM and MEPRO were included as the sole protein source. The SID of AAs was 3% to 5% lower in MEPRO than FM when fed to 30 kg pigs. The SID of arginine and methionine was greater (P<0.05) in MEPRO than FM when fed to 10 kg pigs. The SID of AAs was 12% to 20% lower in FM when fed to 10 v. 30 kg pigs but only 3% to 9% lower in MEPRO. A total of 336 barrows and gilts were weaned at 21 days of age (initial BW=6.1±0.8 kg) and used in a performance trial. Pens of pigs were assigned to one of the six experimental diets (8 pens/diet in two blocks). Treatment diets were fed in Phase I (7 days) and Phase II (14 days) with all pigs fed a common Phase III diet (14 days). Experimental diets included (1) negative control (NEG) containing corn, soybean meal and whey, (2) NEG+acidifier, (3) NEG+FM (POS), (4) POS+acidifier (POS A+), (5) NEG+MEPRO (MEPRO) and (6) MEPRO+acidifier. The FM and MEPRO were included at 7.5% and 5.0% in Phase I and II diets, respectively. Diets were formulated to meet the standard nutrient requirements for weaned pigs. Pig BW and feed disappearance was measured weekly and fecal scores were measured daily for the first 14 days post-weaning as an indicator of post-weaning diarrhea syndrome (PWDS). Performance (BW, daily gain, feed intake and gain : feed) was not significantly different among treatments. Treatment for PWDS occurred on different days in each block. Analysis of fecal score was completed separately by block. Pigs fed the NEG diets had higher (P=0.02) fecal scores than pigs fed the POS diets on days 2 and 3 (block 1) and higher (P<0.05) than pigs fed MEPRO or POS diets and diets with dietary acidifier on days 6 and 3 (block 2). The MEPRO holds promise as an alternative to FM in nursery pig diets.     

Administration of the stress protein gp96 prolongs rat cardiac allograft survival, modifies rejection-associated inflammatory events, and induces a state of peripheral T-cell hyporesponsiveness

High-dose gp96 has been shown to inhibit experimental autoimmune disease by a mechanism that appears to involve immunoregulatory CD4+ T cells. This study tested the hypothesis that high-dose gp96 administration modifies allograft rejection and associated inflammatory events. Wistar cardiac allografts were transplanted into Lewis recipient rats and graft function was monitored daily by palpation. Intradermal administration of gp96 purified from Wistar rat livers (100 microg) at the time of transplantation and 3 days later significantly prolonged allograft survival (14 vs 8 days in phosphate-buffered saline [PBS]-treated recipients; P = 0.009). Rejected allografts from gp96-treated animals were significantly less enlarged than allografts from their PBS-treated counterparts (2.8 vs 4.3 g; P < 0.004). Gp96 was also effective when administered on days 1 and 8 (13 vs 7 days), but not if it was derived from recipient (Lewis) liver tissue or administered on days 0, 3, and 6. In parallel studies, CD3+ T cells from gp96-treated untransplanted animals secreted less interleukin (IL)-4, IL-10, and interferon (IFN)-gamma after in vitro polyclonal stimulation than CD3+ T cells from PBS-treated animals. Gp96 administration might therefore influence the induction of immunity to coencountered antigenic challenges and inflammatory events by inducing what appears to be a state of peripheral T-cell hyporesponsiveness.     

Effect of egg storage duration and brooding temperatures on chick growth,intestine morphology and nutrient transporters

The effects of egg storage duration (ESD) and brooding temperature (BT) on BW, intestine development and nutrient transporters of broiler chicks were investigated. A total of 396 chicks obtained from eggs stored at 18°C for 3 days (ESD3-18°C) or at 14°C for 14 days (ESD14-14°C) before incubation were exposed to three BTs. Temperatures were initially set at 32°C, 34°C and 30°C for control (BT-Cont), high (BT-High) and low (BT-Low) BTs, respectively. Brooding temperatures were decreased by 2°C each at days 2, 7, 14 and 21. Body weight was measured at the day of hatch, 2, 7, 14, 21, 28 and 42. Cloacal temperatures of broilers were recorded from 1 to 14 days. Intestinal morphology and gene expression levels of H⁺-dependent peptide transporter (PepT1) and Na-dependent glucose (SGLT1) were evaluated on the day of hatch and 14. Cloacal temperatures of chicks were affected by BTs from days 1 to 8, being the lowest for BT-Low chicks. BT-High resulted in the heaviest BWs at 7 days, especially for ESD14-14°C chicks. This result was consistent with longer villus and larger villus area of ESD14-14°C chicks at BT-High conditions. From 14 days to slaughter age, BT had no effect on broiler weight. ESD3-18°C chicks were heavier than ESD14-14°C chicks up to 28 days. The PepT1 and SGLT1 expression levels were significantly higher in ESD3-18°C chicks than ESD14-14°C on the day of hatch. There was significant egg storage by BT interaction for PepT1 and SGLT1 transporters at day 14. ESD14-14°C chicks had significantly higher expression of PepT1 and SGLT1 at BT-Low than those at BT-Cont. ESD14-14°C chicks upregulated PepT1 gene expression 1.15 and 1.57-fold at BT-High and BT-Low, respectively, compared with BT-Cont, whereas PepT1 expression was downregulated 0.67 and 0.62-fold in ESD3-18°C chicks at BT-High and BT-Low. These results indicated that pre-incubation egg storage conditions and BTs affected intestine morphology and PepT1 and SGLT1 nutrient transporters expression in broiler chicks.     

Increased ovulation rate in gilts after oral administration of epostane

In Phase I of this study to enhance ovulation rate and hence litter size, gilts received 0 (sham control), 0.625, 1.25, 2.5 or 5.0 mg epostane/kg body weight on Days 10, 11 and 12 of the oestrous cycle (5 gilts/group). After epostane treatment, plasma progesterone concentrations were reduced (P less than 0.01) in a dose-related manner, % progesterone decline = 21.30 x square root of (dose) + 10.45, R2 = 0.70, but recovered to pretreatment levels by 24 h. In Phase II the effects of epostane on ovulation rate and litter size were tested at two study centres. At each centre 108 gilts were treated with the same doses of epostane as used in Phase I and the doses were given for 7 days (Days 15-21) or 12 days (Days 10-21) during the first oestrous cycle. Gilts were inseminated twice during the oestrus after treatment and were slaughtered 30 days later. Mean (+/- s.d.) ovulation rate was 16 +/- 2.7 (N = 8) and 21 +/- 4.0 (N = 61) for control and epostane-treated gilts in Centre A and 12 +/- 2.4 (N = 5) and 17 +/- 3.8 (N = 55) respectively in Centre B (P less than 0.01 for both) and was dose related (ovulation rate = 3.38 x square root of (dose) + 16.17, R2 = 0.31). The effects of 7- or 12-day epostane treatment on ovulation rate were not different (P greater than 0.05), indicating that effects of treatment after Day 14 of the oestrous cycle are most important to subsequent ovulation frequency.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ovarian follicular development and hormone concentrations in inseminated dairy cows with resynchronized estrous cycles

The objective was to investigate ovarian follicular development and hormone concentrations in previously inseminated cows with estrous cycles resynchronized with various resynchronization treatments. Lactating dairy cows were treated with a previously used intravaginal progesterone releasing device (IVD) for 7d (EB+IVD 7+EB, n=15) or 8d (EB+IVD 8+EB, n=16), starting 13d (Day 13) after a first estrus (Day 0) and AI. Estradiol benzoate (EB; 1mgim) was given at device insertion and 24h after removal. Other cows were given the same treatment as the EB+IVD 8+EB cows, but were not treated with EB at IVD insertion (IVD 8+EB, n=11). There were no differences (P>0.05) between EB+IVD 7+EB and EB+IVD 8+EB treatments for follicle dynamics and plasma progesterone concentrations during treatment. Based on a comparison between the IVD 8+EB treated cows and the pooled results of the EB+IVD 7+EB and EB+IVD 8+EB treated cows, EB at device insertion increased the number of follicular waves between Days 13 and 20 (mean+/-S.E.M.; 2.3+/-0.14 vs 2.7+/-0.10, P=0.033), delayed emergence of follicles that were dominant or emerging on Day 20 (17.2+/-0.36 vs 14.1+/-0.65d, P<0.001), reduced diameters of dominant or emerging follicles on Day 20 (9.0+/-0.58 vs 12.7+/-0.59, P<0.001), and reduced plasma progesterone concentrations by 0.85+/-0.44ng/mL (P=0.059) during treatment. Furthermore, comparison of the IVD 8+EB to the EB+IVD 8+EB treated cows demonstrated that treatment with EB at device insertion also reduced the diameter of ovulatory follicles (14.2+/-0.58 vs 19.0+/-0.71mm, P=0.001), delayed emergence of ovulatory follicles (17.0+/-0.32 vs 13.5+/-1.26, P=0.020), and reduced the interval from emergence to ovulation (7.0+/-0.32 vs 10.5+/-1.26d, P=0.020). We concluded that administration of EB altered ovarian follicular dynamics and tended to reduce plasma progesterone concentrations during treatment with an IVD that was used to resynchronize estrous cycles. However, use of a 7-d compared to an 8-day treatment with an IVD did not significantly affect follicle dynamics nor plasma progesterone concentrations during treatment.     

低氧诱导因子脯氨酰羟化酶与OS－9在大鼠低氧肺动脉高压中的协同作用

目的：研究HIF-1α、PHDs及OS-9的表达变化在低氧性肺动脉高压（HPH）中的作用和意义。方法：SD大鼠随机分5组（n=8）;对照组（C组）和低氧3、7、14和21d组,常压低氧复制HPH大鼠模型。原位杂交、RT-PCR检测mRNA表达,免疫组化、Westernblot检测蛋白质表达。结果：①HIF-1αmRNA对照纽和低氧3d无明显差异,低氧14d后表达明显增高;HIF-1α蛋白质低氧3d组表达明显增高,7d达高峰;②对照组PHD1mRNA呈阳性表达,各低氧组与对照组比较差异不显著,PHD1蛋白质在对照组强阳性表达,低氧14d下降,低氧21d保持较低水平;对照组PHD2mRNA呈阳性表达,低氧3d增高,14d达到高峰,21d维持高水平,其蛋白质表达趋势与mRNA相同;对照组PHD3mRNA和蛋白质表达不明显,低氧3dmRNA明显增高,蛋白质低氧3d明显增高,低氧7d保持高水平,低氧14d和21d下降。③OS-9mRNA在对照组呈强阳性表达,低氧3d后迅速降低,14d达到最低水平;其蛋白质表达趋势与mRNA相同。相关分析表明,肺小动脉壁OS-9蛋白质表达水平与OS-9mRNA呈正相关,与RVHI、mPAP、WA％及LA％呈负相关。结论：HIF-1α、PHDs及OS-9均在大鼠HPH的发病机制中发挥作用。OS-9可能通过增强PHDs的活性来调节HIF-1α的表达,从而在HPH的发生和发展中发挥作用。     

Roles of Mg2+ in the mechanism of formation and dissociation of open complexes between Escherichia coli RNA polymerase and the lambda PR promoter: kinetic evidence for a second open complex requiring Mg2+.

Comparative studies of the effects of Mg2+ vs Na+ and of acetate (OAc-) vs Cl- on the kinetics of formation and dissociation of E. coli RNA polymerase (E sigma 70)-lambda PR promoter open complexes have been used to probe the mechanism of this interaction. Composite second-order association rate constants ka and first-order dissociation rate constants kd, and their power dependences on salt concentration SKa (SKa identical to d log ka/d log [salt]) and Skd (Skd identical to d log kd/d log [salt]), were determined in MgCl2 and NaOAc to compare with the results of Roe and Record (1985) in NaCl. Replacement of NaCl by MgCl2 reduces the magnitude of Ska 2-fold (Ska = -11.9 +/- 1.1 in NaCl; Ska = -5.2 +/- 0.3 in MgCl2) and (by extrapolation) drastically reduces the magnitude of ka at any specified salt concentration (e.g., approximately 10(6)-fold at 0.2 M). Replacement of NaCl by NaOAc does not significantly affect Ska (Ska = -12.0 +/- 0.7 in NaOAc) and (by extrapolation) increased ka by approximately 80-fold at any fixed [Na+]. In the absence of Mg2+, replacement of NaCl by NaOAc is found to increase the half-life of the open complex by approximately 560-fold at fixed [Na+] without affecting Skd [Skd = 7.6 +/- 0.1 in NaOAc; in NaCl, Skd = 7.7 +/- 0.2 (Roe & Record, 1985)]. Replacement of NaCl by MgCl2 drastically reduces both Skd and the half-life of the open complex at any salt concentration below approximately 0.2 M. Strikingly, Skd = 0.4 +/- 0.1 in MgCl2, indicating that the net uptake of Mg2+ ions in the kinetically significant steps in dissociation of the open complex is much smaller than that expected by analogy with the uptake of approximately 8 Na+ ions in the corresponding steps in NaCl. In NaCl/MgCl2 mixtures, at a constant [NaCl] in the range 0.1-0.2 M, initial addition of MgCl2 (0.5 mM less than or equal to [MgCl2] less than or equal to 1 mM) increases the half-life of the open complex; further addition of MgCl2 causes the half-life to decrease, though the effect of [MgCl2] on kd is always less than that predicted by a simple competitive model. The observed effects of MgCl2 on Skd and kd differ profoundly from those expected from the behavior of kd and Skd in NaCl and NaOAc and indicate that the role of Mg2+ in dissociation is not merely that of a nonspecific divalent competitor with RNAP for interactions with DNA phosphates and of a DNA helix-stabilizer, both of which should cause kd to increase monotonically with increasing [Mg2+].(ABSTRACT TRUNCATED AT 400 WORDS)     

Cryopreservation of Specific Pathogen-Free (SPF) Pig Islet Cells: Effect of Culture Time before Cryopreservation and after Thawing

The aim of this study was to determine the optimal conditions (effect of culture time before and after cryopreservation) for cryopreservation of specific pathogen-free pig islet cells. METHODS: (1) Glucose-induced insulin secretion by fresh islet cells cultured for 10 days was compared to that by islet cells cryopreserved 7 days after isolation and cultured 3 days after thawing. (2) Islet cells were cryopreserved 1, 7, or 14 days after isolation and cultured 3, 7, 14, or 21 days after thawing. Islet cell number, insulin content, and insulin response under perifusion tests were investigated. RESULTS: (1) Insulin response by cryopreserved islet cells was identical to that by fresh islet cells (basal/stimulation index: 2. 13 +/- 0.19 vs 2.17 +/- 0.16, n = 4, NS), although the amount of secreted insulin was reduced by 40% (area under the curve: 2136 +/- 198 pM/10(4) cells/180 min vs 3564 +/- 636 pM/10(4) cells/180 min, P = 0.104). (2) Cell number 6 days after thawing was reduced by 54, 40, and 63% when cryopreservations were carried out at D1, D7, and D14. (3) Insulin content in cultured or cryopreserved islet cells increased between 7 and 14 days of culture. (4) Whatever the culture time before and after cryopreservation, insulin secretion in response to glucose was maintained. The insulin release was the highest for islet cells cryopreserved 14 days after isolation and cultured 14 days after thawing (stimulation index: 6.19 +/- 2.68). CONCLUSIONS: SPF pig islet cells remained functional after cryopreservation in polyethylene glycol and it may be important to culture islet cells over 14 days before and after cryopreservation.     

The influence of insulin administration after weaning the first litter on ovulation rate and embryo survival in sows

Primiparous crossbred sows (n = 43), lactating for an average of 21.1 +/- 0.1 d and weaning 8.7 +/- 0.1 pigs, were used to evaluate the influence of insulin on ovulation rate and embryo survival. The sows were maintained on 2.3 kg/head/d of a 14% protein gestation diet during pregnancy, fed ad libitum during lactation, given 2.7 kg/head/d from weaning until re-breeding and fed 2.3 kg/head/d after mating. Beginning the day after weaning (Day 0) sows were treated with 0.4 IU/kg body weight (BW) insulin (n = 21) or were administered an equivalent volume of saline (n = 22) for 4 d. Beginning on Day 3 and continuing until Day 14 after weaning, the sows were checked for estrus twice daily and were artificially inseminated using pooled semen from 2 fertile boars. At slaughter (days 30 to 40 of gestation), ovaries and uteri were collected, and the ovulation rate, embryo number and viability, and uterine weight and length were evaluated and recorded. Use of insulin decreased the average interval from weaning to estrus compared with saline by increasing percentage in estrus by Day 14 after weaning (5.0 +/- 0.57 vs 6.9 +/- 0.56 d, respectively; P < 0.03). Ovulation rate, number of embryos, embryo survival, and average uterine length and weight were not influenced by insulin treatment. Overall, insulin affected reproductive efficiency in primiparous sows by increasing the percentage of sows in estrus.     

Age, body weight and backfat thickness at first observed oestrus in crossbred Landrace x Yorkshire gilts, seasonal variations and their influence on subsequence reproductive performance

The objective of the present study was to investigate puberty attainment in crossbred Landrace x Yorkshire (LY) gilts reared under tropical conditions and their subsequent reproductive performance. This study was carried out in a 2400-sow herd over a 1-year period. A total of 696 crossbred LY replacement gilts were included. Faecal samples from 214 gilts were collected to determine the faecal progesterone profiles around the time of first oestrus. Solid-phase 125I-radioimmunoassay was used to determine the progesterone concentrations in the faecal extract. The gilts entered the herd at an average age of 177.5 +/- 12.6 days, 95.7 +/- 10.2 kg body weight (BW) and a backfat thickness (BF) of 12.0 +/- 2.9 mm. On average, the gilts expressed first standing oestrus at 195 days of age, 106 kg of BW and a BF of 13.0 mm. The interval from entry to the gilt pool to the first observed oestrus (EOI) was 24.4 +/- 18.0 days (range 0-88 days). The hormonal profile indicated that the gilts that actually ovulated during the first observed oestrus was 34% (group A), the gilts that had ovulated before the first observed oestrus was 21% (group B) and the gilts that did not ovulate during the first observed oestrus was 45% (group C). During summer the proportion of group A gilts was significantly lower than during the winter and the rainy seasons (P < 0.05). The BW of gilts at entry significantly correlated with the BF at entry (r = 0.31, P < 0.001), the age at entry (r = 0.47, P < 0.001), the BW at first oestrus (r = 0.65, P < 0.001) and the BF at first oestrus (r = 0.33, P < 0.001). An increase of BW at entry of 1 kg resulted in a decrease of EOI of 0.28 days. The age, BW and BF of gilts at the first observed oestrus significantly influenced the total number of piglets born per litter (TB) and the number of piglets born alive per litter (BA) in the first three parities. Gilts expressing their first oestrus between 181 and 200 days had a significantly larger TB than gilts that expressed first oestrus between 150 and 180 days (P = 0.03) and between 201 and 220 days (P = 0.003). Gilts that showed first oestrus between 110.1 and 120.0 kg had a larger TB and BA than gilts that showed first oestrus between 80.0 and 100.0 kg (P < 0.05). Gilts that showed first oestrus with a BF between 13.1 and 15.0 mm had a larger TB and BA than gilts that showed first oestrus with a BF between 11.1 and 13.0 mm (P < 0.05). Group A gilts had a significantly larger TB than group B (10.5 piglets/L versus 9.4 piglets/L, P = 0.02), while farrowing rate (FR) did not differ significantly among groups A, B and C (78.1, 76.9 and 77.6%, respectively). Gilts that farrowed in the summer had a larger TB and BA than gilts that farrowed in the winter (TB, P = 0.03; BA, P = 0.09) and the rainy season (TB, P = 0.006; BA, P = 0.003). In conclusion, LY gilts reared under tropical conditions expressed first standing oestrus at 195 days of age, 106 kg BW and a BF of 13.0 mm. Under field conditions, 21% of the gilts with an observed oestrus had ovulated. The proportion of gilts that showed first oestrus and ovulated normally was lowest during the summer. The age, BW and BF at first observed oestrus influenced subsequent reproductive performance over the first three parities. The mean litter size (TB and BA) in the first three parities were highest in gilts that had a first observed oestrus between 181 and 200 days with 110.1-120.0 kg BW and 13.1-15.0 mm BF.