日粮硝酸盐水平对湖羊瘤胃硝态氮动态消失率、发酵参数及血液高铁血红蛋白含量的影响

本试验研究日粮硝酸盐的添加量对湖羊瘤胃还原硝态氮程度和对发酵参数及血液高铁血红蛋白的影响。试验选取6头湖羊,采用随机区组试验设计,每期分别饲喂含0%,1%,2%,3%,4%,5%硝酸钾的日粮。测定喂后0,0.5,1.0,1.5,2.0,4.0,6.0,8.0 h瘤胃液硝酸盐和亚硝酸盐含量及瘤胃发酵参数。晨饲后2.0 h通过颈静脉采血,测定高铁血红蛋白含量。结果表明,湖羊在采食1.0 h后硝酸盐含量达到最高(0.952.14 g/L),之后快速消失,亚硝酸盐含量在喂后1.5 h达到最高(0.936.22 μmol/L),之后降低。高铁血红蛋白的含量随硝酸盐添加量的增加而显著升高(P<0.01),最高达0.32%。添加硝酸盐显著提高瘤胃液pH值(P<0.01)和2.0 h的氨态氮含量(P<0.01)以及乙酸/丙酸,添加量高于3%会降低微生物蛋白和总挥发性脂肪酸的浓度,2%的硝酸盐添加量微生物蛋白和总挥发性脂肪酸的合成量最高,最有利于微生物发酵。     

Effect of ethanol on nitrate and nitrite reduction and methanogenesis in the ruminal microbiota

The effect of ethanol on nitrate and nitrite reduction was examined by conducting in vitro experiments with mixed ruminal microbes. The addition of ethanol to cultures of mixed ruminal microbes stimulated nitrate reduction, and, to a greater extent, nitrite reduction, which resulted in a decrease in nitrite accumulation. However, known nitrate‐reducing ruminal bacteria, such as Selenomonas ruminantium, Veillonella parvula and Wolinella succinogenes, were unable to utilize ethanol directly as an electron donor for nitrate reduction. No nitrate‐reducing bacterium capable of utilizing ethanol was found in the rumen of goats. However, when mixed ethanol‐utilizing, hydrogen gas (H₂)‐producing bacteria (Ruminococcus albus and Ruminococcus flavefaciens) were added to the culture of the mixed nitrate‐reducing bacteria described above, nitrate and nitrite reduction was observed. These results suggest that the nitrate‐reducing bacteria utilized the H₂ that was produced from ethanol oxidation by the ethanol‐utilizing bacteria as an electron donor. It is conceivable that the stimulation of nitrate and nitrite reduction by ethanol, observed in the culture of mixed ruminal microbes, was a result of electron transfer from ethanol to nitrate, and nitrite through H₂, that is, ‘interspecies hydrogen transfer’ from ethanol‐metabolizing bacteria to nitrate‐reducing bacteria. Thus, the addition of ethanol to high‐nitrate diets may be effective for preventing nitrate poisoning. Furthermore, methane production was reduced to less than one‐third by the addition of mixed nitrate‐reducing bacteria to the co‐culture of mixed methanogens with mixed ethanol‐utilizing bacteria incubated in a medium containing ethanol and nitrate. Therefore, the addition of ethanol and nitrate may decrease methanogenesis without suppressing overall fermentation in the rumen.     

Number of nitrate- and nitrite-reducing Selenomonas ruminantium in the rumen, and possible factors affecting its growth

The cell number of Selenomonas ruminantium (S. ruminantium) that reduces nitrate and nitrite in the rumen was usually 8–10% of the total number of S. ruminantium (an order of 10⁶/mL). The percentage was not affected by the roughage/concentrate ratio or nitrate content of the diet in 2 weeks. However, feeding a high‐nitrate diet for 12 weeks increased the percentage. The percentage of lactate‐using S. ruminantium, such as the ssp. lactilytica, was less than 1% of the total number of S. ruminantium. No S. ruminantium was found that used formate as an electron donor for nitrate and nitrite reduction. Lactate and H₂ appeared to be important for nitrate and nitrite reduction by S. ruminantium. Nitrate reduction by S. ruminantium was enhanced by the coexistence of amylolytic bacteria in a medium containing starch, and as a result, nitrite accumulation increased. Coexistence of cellulolytic bacteria facilitated the growth of S. ruminantium in a medium containing cellulose, and consequently increased nitrite reduction. In order to suppress nitrite accumulation in the rumen, it may be important to enhance fiber digestion.     

3种饲草组合对湖羊瘤胃还原硝酸盐过程的影响

采用3×3拉丁方试验设计,研究以燕麦(Avena sativa)或苜蓿(Medicago sativa)干草等比例替代羊草(Leymus chinensis)后,对饲草中硝酸盐动态消失率及湖羊瘤胃发酵参数的影响。晨饲后0、1、2、3、4、5和6h通过瘤胃瘘管采集湖羊瘤胃液,测定瘤胃pH值以及硝酸盐(NO_3~-)、亚硝酸盐(NO_2~-)、氨态氮(NH_3-N)的浓度;同时,晨饲后2h经颈静脉采血测定血清高铁血红蛋白含量。结果表明,1)3组瘤胃液NO_3~-和NO_2~-浓度分别在喂后1和2h达到最大值,之后迅速降低;2)pH值、NO_3~-、NO_2~-浓度各组间均无显著差异(P0.05);NH_3-N仅在饲喂3h后全羊草组(A组)显著低于其它两组(P=0.018);3)高铁血红蛋白含量均较低,且无显著差异(P0.05)。本研究选用的牧草组合对湖羊瘤胃还原硝酸盐过程没有显著影响。     

Effects of nitrate addition to a diet on fermentation and microbial populations in the rumen of goats,with special reference to Selenomonas ruminantium having the ability to reduce nitrate and nitrite

This study investigated the effects of dietary nitrate addition on ruminal fermentation characteristics and microbial populations in goats. The involvement of Selenomonas ruminantium in nitrate and nitrite reduction in the rumen was also examined. As the result of nitrate feeding, the total concentration of ruminal volatile fatty acids decreased, whereas the acetate : propionate ratio and the concentrations of ammonia and lactate increased. Populations of methanogens, protozoa and fungi, as estimated by real‐time PCR, were greatly decreased as a result of nitrate inclusion in the diet. There was modest or little impact of nitrate on the populations of prevailing species or genus of bacteria in the rumen, whereas Streptococcus bovis and S. ruminantium significantly increased. Both the activities of nitrate reductase (NaR) and nitrite reductase (NiR) per total mass of ruminal bacteria were increased by nitrate feeding. Quantification of the genes encoding NaR and NiR by real‐time PCR with primers specific for S. ruminantium showed that these genes were increased by feeding nitrate, suggesting that the growth of nitrate‐ and nitrite‐reducing S. ruminantium is stimulated by nitrate addition. Thus, S. ruminantium is likely to play a major role in nitrate and nitrite reduction in the rumen.     

Effects of tryptophan supplementation on aggression among group-housed gestating sows

The objective of this study was to determine the effects of dietary Trp supplementation on mixing-induced aggression and the associated stress, and on reproductive performance in gestating sows. After weaning, sows were mixed in pens with electronic sow feeders on concrete-slatted floors. Each pen housed 21 ± 2.8 sows, with approximately 2.7 ± 0.43 m(2)/sow of floor space allowance. Multiparous sows (n = 168) from 8 breeding groups were used, with 4 groups assigned to a control diet and 4 groups assigned to a high-Trp diet. Control sows received corn- and soybean meal-based diets throughout gestation (0.15% Trp) and lactation (0.21% Trp). Three days before and after mixing, sows assigned to the high-Trp treatment received approximately 2.3 times the dietary Trp (0.35% in the gestation diet and 0.48% in the lactation diet) fed to control sows. Six focal sows (2 sows from each of parity 1, 2, and 3 or greater) in each pen were designated and videotaped for 72 h after mixing to determine the type and number of aggressive interactions among sows. Before and 48 h after mixing, saliva samples were collected from focal sows, and scratches were assessed on all sows. Data were analyzed using the FREQ and GLIMMIX procedures (SAS Inst. Inc., Cary, NC). Aggression among sows was intense during the initial 6 h and decreased between 6 and 72 h after mixing. The initial aggression caused scratches and increased cortisol concentrations (P < 0.05). Mature sows tended to fight for longer periods (112 vs. 52 s/h per sow, SE = 23.8; P < 0.10) but had fewer scratches caused by aggression (injury score = 4.3 vs. 6.5, SE = 1.13; P < 0.01) than parity-1 sows. Supplementation of dietary Trp reduced the total duration of head-to-head knocking (P < 0.05) but did not affect other aggressive behaviors. There was no difference between dietary treatments in injury scores or saliva cortisol concentrations. Sows in the high-Trp treatment had more total piglets born (12.5 vs. 10.5 pigs/litter, SE = 0.55; P < 0.05) and more stillborn piglets (1.5 vs. 0.8 pigs/litter, SE = 0.20; P < 0.05), but had no significant change (P = 0.12) in piglets born alive (10.8 vs. 9.7 pigs/litter, SE = 0.42) compared with control sows. The results indicate that the initial aggression after mixing caused more injuries in young sows than in mature sows. Supplementation of dietary Trp at 2.3 times the control amount for a short period did not effectively reduce aggression and the associated stress in sows at mixing.     

Growth performance of piglets during the first two weeks of lactation affects the development of the intestinal microbiota

The aim of this study was to evaluate the effect of newborn piglet weight gain during the first 2 weeks of lactation on the luminal and mucosal microbiota of the ileum and colon. The microbiota from high‐weight‐gain (HWG) and low‐weight‐gain (LWG) 2‐week‐old piglets was characterized by amplicon length heterogeneity PCR (LH‐PCR) and compared using diversity indices and multivariate statistical analyses. At birth, LWG piglets weighted in average 0.26 kg less than HWG piglets (p = .002). The weight difference between LWG and HWG piglets increased with time and reached 2.1 kg after 16 days of lactation (p < .0001). Based on these growth performance differences, estimated colostrum and milk intake was greater in HWG than in LWG piglets (p < .0001). Analysis of the LH‐PCR data of the microbiota using non‐metric multidimensional scaling (NMS) and blocked multiresponse permutation procedure (MRBP) revealed that the microbiota of the HWG and LWG piglets tended to differ in ileal mucosa (p = .097) and differed in colonic lumen (p = .024). The microbiota of HWG piglets had higher levels of Bacteroidetes, Bacteroides and Ruminoccocaceae, and lower proportions of Actinobacillus porcinus and Lactobacillus amylovorus when compared with those of LWG piglets. As the weight gain of nursing piglets is highly correlated with the amount of ingested colostrum and milk, the results strongly suggest that colostrum and milk intake in the first 2 weeks of life influenced the development of the gut microbiota.     

Effect of Escherichia coli wild type or its derivative with high nitrite reductase activity on in vitro ruminal methanogenesis and nitrate/nitrite reduction

The effects of two kinds of Escherichia coli strains, wild-type E. coli W3110 or E. coli nir-Ptac, which has enhanced nitrite reduction activity, on in vitro CH4 production and nitrate and nitrite reduction in cultures of mixed ruminal microorganisms was investigated using continuous incubation systems. Escherichia coli nir-Ptac, a derivative of wild-type E. coli W3110, was constructed by replacing self promoter of nir BD operon encoding subunits of nitrite reductase in E. coli W3110 by tac promoter to make the expression of nir BD higher and constitutive. The nitrite reductase activity of E. coli nir-Ptac was approximately twice as high as E. coli W3110. The culture media consisted of 400 mL of strained ruminal fluid taken from two nonlactating Holstein cows receiving a basal diet of orchardgrass hay at maintenance level (55 g of DM/kg of BW0.75 daily), and 400 mL of autoclaved artificial saliva. Treatments were arranged in two separate 3 x 3 factorials consisting of nitrate (NaNO3; 0, 5, or 10 mM) without E. coli or inoculated with E. coli W3110 or E. coli nir-Ptac, or nitrite (NaNO2; 0, 1 or 2 mM) without E. coli or inoculated with E. coli W3110 or E. coli nir-Ptac. The control culture contained no chemical or microbial additives. Escherichia coli cells were inoculated into in vitro mixed ruminal cultures at approximately 2 x 10(8) to 10(9) cells/mL. Methane production by ruminal microorganisms was decreased markedly (P < 0.001) by the addition of nitrate and nitrite, and by the inoculation of cultures with E. coli W3110 or E. coli nir-Ptac (P < 0.01). With mixed nitrite-containing cultures, E. coli nir-Ptac inhibited (P < 0.001) in vitro nitrite accumulation and CH4 production more than E. coli W3110, which may be due to the tac promoter-enhanced nitrite reductase activity of E. coli nir-Ptac accelerating electrons to be consumed for nitrite reduction rather than CH4 biosynthesis. In conclusion, anaerobic cultures of E. coli W3110 or E. coli nir-Ptac may decrease CH4 production in the rumen. The inoculation of E. coli W3110 or, especially, E. coli nir-Ptac to mixed ruminal microorganisms may decrease nitrite toxicity when ruminants consume high-nitrate-containing forages and when nitrite is applied to abate ruminal CH4 production.     

Methemoglobinemia in pigs and the effect of nitrites on the health and growth of piglets

In 357 pigs of ten age categories fed the commercial feed mixtures the highest methemoglobinemia was found in piglets up to three days of age (3.62%) and the lowest in sows and boars (2.25%). In twelve per cent of animals of the whole set the values of methemoglobin (MHb) reached or exceeded 4%, the maximum was 8.1%, without any clinical symptoms. Except the anemic piglets, these values were not observed in sucking piglets older than three days. Testing of the formation and of the subsequent reduction of methemoglobin in vitro by the action of 14.4 micrograms of sodium nitrite in 1 ml of blood proved no increased disposition to methemoglobinemia in new-born piglets. The levels with 29 to 40% of methemoglobin reached their peaks in all age groups within 50 min. The reconversion was the slowest in adult pigs, the quickest in new-born and weaned piglets; after seven hours the reconversion was almost complete. If recalculated to the initial concentration of hemoglobin, its highest transformation to methemoglobin occurred in older and adult pigs, the lowest in the piglets up to the age of six days and at sideropenic anemia. Short-term administration of sodium nitrite to sows prior to delivery resulted in an increased methemoglobin level in new-born piglets, out o of which 12% were still-born. The repeated administration of sodium nitrite to the sucking piglets (33 to 132 mg per day) influenced neither their health condition nor the body weight gains. The effects of nitrates, nitrites and mechanisms of the reconversion of methemoglobin to hemoglobin are discussed.     

Postnatal changes of plasma amino acids in suckling pigs

Amino acids, ammonia, urea, orotate, and nitrate plus nitrite (stable oxidation products of nitric oxide) were determined in plasma of 1- to 21-d-old suckling pigs. Jugular venous blood samples were obtained from pigs at 1, 3, 7, 14, and 21 d of age for analysis of plasma amino acids and metabolites by HPLC and enzymatic methods. Plasma concentrations of arginine and its immediate precursors (citrulline and ornithine) decreased (P < 0.01) progressively (20 to 41%) with increasing age from 3 to 14 d. Plasma concentrations of glutamine declined (P < 0.01) progressively (10 to 31%) during the 1st wk of life. Plasma concentrations of branched-chain amino acids, threonine, and alanine decreased (P < 0.01) (5 to 12%) in 14- and 21-d-old pigs, compared with 1- and 3-d-old pigs. There were no postnatal changes (P > 0.05) in plasma concentrations of other amino acids. Plasma concentrations of ammonia increased (P < 0.01) by 18 and 46%, whereas those of nitrate plus nitrite decreased (P < 0.01) by 16 and 29%, in 7- and 14-d-old pigs, respectively, compared with 1- to 3-d-old pigs. Because arginine plays a crucial role in ammonia detoxification via the hepatic urea cycle and is the physiological substrate for nitric oxide synthesis, our results of the decreased plasma concentrations of arginine and nitrate plus nitrite, as well as the increased plasma ammonia concentration, indicate a hitherto unrecognized deficiency of arginine in 7- to 21-d-old suckling pigs. Arginine is an essential amino acid for piglets and has a great potential to enhance neonatal growth; therefore, further studies are necessary to elucidate the mechanism responsible for arginine deficiency in sow-reared piglets and to identify hormonal and metabolic means for improving neonatal arginine nutrition and growth.     

外源粪菌干预对受体猪肠道屏障功能的影响研究

为研究外源粪菌干预对受体猪肠道屏障功能的影响,试验选取初生重相近、胎次相同、同日出生的杜×长×大三元杂交哺乳仔猪12窝,随机分为2组,每组6窝(每窝10~12头)。试验组于1~10日龄隔天灌喂1 m L金华猪粪菌悬液进行外源粪菌干预;对照组灌喂等量无菌0.1 mol/L无菌磷酸盐缓冲液(PBS)。试验期间,仔猪自由哺乳采食和饮水,分别于12日龄和27日龄进行屠宰、采样。结果表明:外源粪菌干预可明显减少腹泻,提高受体猪的平均日增重和成活率(P0.05);外源粪菌干预能显著降低27日龄受体猪肠道隐窝深度(P0.05),显著提高肠道绒毛高度/隐窝深度(P0.05);外源粪菌干预能显著增加肠道杯状细胞数和12日龄肠道分泌型免疫球蛋白A阳性(SIgA~+)细胞数(P0.05),同时显著提高肠道黏蛋白Muc2、紧密连接蛋白ZO-1和Occludin表达水平(P0.05),而27日龄试验组的肠道SIgA~+细胞数与对照组无显著差异(P0.05)。综上可知,外源粪菌干预能通过增加肠道杯状细胞和SIgA~+细胞数、提高黏蛋白和紧密连接蛋白表达的方式调节受体猪肠道屏障功能,具有维持猪肠道功能稳态和促进肠道健康的作用。     

Eating and drinking activity of newly weaned piglets: effects of individual characteristics, social mixing, and addition of extra zinc to the feed

In production systems, piglets usually fast for a period after weaning, thereby increasing the risk of diarrhea and a reduction in growth. The low level of eating may relate to insufficient drinking activity, as solid feed intake must be accompanied by water intake. Mixing of newly weaned piglets is a well-known stressor and a common procedure in pig production. The effect of mixing on the temporal development of eating and drinking activity in newly weaned piglets has not been elucidated. High concentrations of zinc (Zn) in the feed improve the health and performance of piglets after weaning, but the underlying mechanisms are still obscure. One possibility is that Zn affects eating and drinking behavior. The effects of mixing 4 littermates from each of 2 litters and adding zinc oxide (ZnO; 2,500 ppm of Zn) to the feed were studied in a 2 x 2 factorial experiment using 123 piglets weaned at 27 d of age. Individual eating and drinking times during the initial 48 h after weaning were analyzed on 2 levels of aggregation, day and hour. The piglets spent less time eating on the first day after weaning compared with the second day (20 +/- 5 vs. 98 +/- 10 min, respectively; P < 0.001), whereas they spent more time drinking on the first day compared with the second day (13 +/- 1 vs. 9 +/- 0.5 min, respectively; P < 0.001). Eating and drinking times were positively associated (P < 0.001). Females ate for longer than males (61 +/- 8 vs. 44 +/- 7 min/24 h, respectively, P = 0.002), whereas sex did not affect drinking time. Drinking time increased (P = 0.003) and eating time decreased (P = 0.001) with increasing preweaning growth rate and weaning weight. Neither mixing nor addition of ZnO affected the daily eating time. However, nonmixed piglets given 2,500 ppm of Zn as ZnO in the feed spent more time drinking per day (12 +/- 1 min) than did nonmixed piglets offered 100 ppm of Zn as ZnO (10 +/- 1 min; P = 0.002). Mixing also affected the hourly distribution of the drinking activity (P < 0.05). In conclusion, the drinking behavior of newly weaned piglets was more affected by the external factors, mixing and addition of ZnO to the feed, than the eating behavior. As eating and drinking are strongly associated, more focus should be paid to the water intake and the interplay between eating and drinking behavior in future studies aiming to reduce weaning problems.     

The effects of starter microbiota and the early life feeding of medium chain triglycerides on the gastric transcriptome profile of 2-or 3-week-old cesarean delivered piglets

Background: The stomach is an underestimated key interface between the ingesta and the digestive system, affecting the digestion and playing an important role in several endocrine functions. The quality of starter microbiota and the early life feeding of medium chain triglycerides may affect porcine gastric maturation. Two trials(T1, T2) were carried out on 12 and 24 cesarean-delivered piglets(birth, d0), divided over two microbiota treatments, but slaughtered and sampled at two or three weeks of age, respectively. All piglets were fed orally: sow serum(T1) or pasteurized sow colostrum(T2) on d0; simple starter microbiota(Lactobacillus amylovorus, Clostridium glycolicum and Parabacteroides spp.)(d1-d3); complex microbiota inoculum(sow diluted feces, CA) or a placebo(simple association, SA)(d3-d4) and milk replacer ad libitum(d0-d4). The The T1 piglets and half of the T2 piglets were then fed a moist diet(CTRL); the remaining half of the T2 piglets were fed the CTRL diet fortified with medium chain triglycerides and 7% coconut oil(MCT). Total m RNA from the oxyntic mucosa was analyzed using Affymetrix?Porcine Gene array strips. Exploratory functional analysis of the resulting values was carried out using Gene Set Enrichment Analysis.Results: Complex microbiota upregulated 11 gene sets in piglets of each age group vs. SA. Of these sets, 6 were upregulated at both ages, including the set of gene markers of oxyntic mucosa. In comparison with the piglets receiving SA, the CA enriched the genes in the sets related to interferon response when the CTRL diet was given while the same sets were impoverished by CA with the MCT diet.Conclusions: Early colonization with a complex starter microbiota promoted the functional maturation of the oxyntic mucosa in an age-dependent manner. The dietary fatty acid source may have affected the recruitment and the maturation of the immune cells, particularly when the piglets were early associated with a simplified starter microbiota.     

Nitrate poisoning in cattle

Summary

In a series of experiments the effect of administering KNO₂ was studied, during parturition, on the capability of oxygen transport of maternal blood and on oxygen transfer to foetal blood. The following blood parameters were analysed, MHb percentage, pO₂, O₂‐saturation, pH, pCO₂, and (NO₂) in maternal arterial blood (carotid art.) and venous blood (jugular vein) and in foetal arterial blood (umbilical art.) and venous blood (umbilical vein). The relative O₂‐saturation was calculated from the estimated O₂‐saturation by multiplying with the factor Hb (mmol/1) minus MHb (mmol/1), divided by Hb (mmol/1). In addition, blood pressure in the carotid artery, heart rate, and respiration rate in the dam were continuously recorded for some hours.

A dosage of 9 to 12 mg of NO₂/kg body weight intravenously or of 30 mg of NO₂/kg body weight orally to the dam caused much higher MHb percentages and NO₂ contents in the maternal blood than in the foetal blood. In maternal blood the ratio of NO₂ content td MHb percentage was proportional to that in foetal blood. In the arterial blood, MHb percentages were almost as high as in the venous blood. After administering of nitrite, relative O₂‐saturation dropped simultaneously with the increase in methaemoglobin.

Nitrite treatment caused a drop in the maternal blood pressure; heart rate and respiration rate increased. O₂‐saturation in the blood in the umbilical vein was much lower in the animals with nitrite treatment than in those without. These experimental results show clearly that the oxygen capacity of the blood decreases after nitrite treatment. In pregnant cows the oxygen supply to the foetus will be adversely affected after nitrate intake, especially by the lower oxygen transfer via the placenta, though hardly at all by methaemoglobin formation in the foetal blood.

When the oxygen transfer to the foetal blood decreases too sharply, intra‐uterine death and ultimately abortion may result.     

Effects of benzoic acid on performance and ecology of gastrointestinal microbiota in weanling piglets

The effects of feeding benzoic acid on weanling pig performance and on the ecology of their gastrointestinal microbiota were evaluated. One hundred and forty-four piglets (4 weeks of age) were used. Half of the piglets were fed a control diet and half were fed the same diet with 0.5% benzoic acid, and their performance was measured for 28 days. At the end of the trial, twelve piglets from each treatment were euthanised and samples of ileal and caecal digesta were collected. The digesta samples were cultured to quantify Lactobacillus spp., Escherichia coli,Enterococcus spp. and Clostridium perfringens and they were also studied by restriction fragment length polymorphism to evaluate the biodiversity degree and the similarity between the profiles of the microbiota. Benzoic acid improved piglets’ performance, and this was associated with a greater ileal microbiota biodiversity.     

中药复方对保育阶段仔猪血清中胆固醇与脂蛋白的影响

[目的]在基础日粮的水平上添加中药复方,纯中药全程饲喂,对保育阶段仔猪血清中胆固醇和脂蛋白含量进行测定,为该中药复方对保育阶段仔猪增强机体抵抗力,降低抗生素在畜牧业的应用,形成质量可靠的“无抗”猪肉提供帮助。[方法]试验选用80头（28±2）日龄、体重相近的“杜×长×大”三元杂交断奶仔猪,随机分为4个处理,每个处理2个重复,每个重复10头仔猪。第1组为对照组,饲喂基础日粮,第2、3、4组在饲喂基础日粮的基础上分别添加1.5%、1.0%和0.5%的中药复方,试验期4周。试验结束第2天上午9：00空腹,前腔静脉采血,进行全血血常规指标测定。[结果]与对照组相比,饲料中添加中药复方组保育仔猪血清中脂蛋白脂肪酶含量均有升高,其中,添加0.5%中药复方组与对照组相比差异显著（P<0.05）;与对照组相比,饲料中添加中药复方组保育仔猪血清中高密度脂蛋白含量均有升高,其含量随中药复方添加量的减少而逐渐降低,各中药复方添加组与对照组相比差异均不显著（P>0.05）;与对照组相比,饲料中添加中药复方组保育仔猪血清中低密度脂蛋白含量均有所下降,其含量随中药复方添加量的减少而逐渐降低,其中,添加0.5%中药复方组与对照组相比差异极显著（P<0.01）;与对照组相比,饲料中添加中药复方组保育仔猪血清中三酰甘油含量均有下降,其含量随中药复方添加量的减少而逐渐降低,各中药复方添加组与对照组相比差异均不显著（P>0.05）。[结论]在基础日粮中添加中药复方组保育仔猪血清中脂蛋白脂肪酶含量、高密度脂蛋白含量均有升高;保育仔猪血清中低密度脂蛋白含量、三酰甘油含量均有降低。     

Dynamics of the ruminal microbial ecosystem,and inhibition of methanogenesis and propiogenesis in response to nitrate feeding to Holstein calves

It is known that nitrate inhibits ruminal methanogenesis, mainly through competition with hydrogenotrophic methanogens for available hydrogen (H₂) and also through toxic effects on the methanogens. However, there is limited knowledge about its effects on the others members of ruminal microbiota and their metabolites. In this study, we investigated the effects of dietary nitrate inclusion on enteric methane (CH₄) emission, temporal changes in ruminal microbiota, and fermentation in Holstein calves. Eighteen animals were maintained in individual pens for 45 d. Animals were randomly allocated to either a control (CTR) or nitrate (NIT, containing 15 g of calcium nitrate/kg dry matter) diets. Methane emissions were estimated using the sulfur hexafluoride (SF₆) tracer method. Ruminal microbiota changes and ruminal fermentation were evaluated at 0, 4, and 8 h post-feeding. In this study, feed dry matter intake (DMI) did not differ between dietary treatments (P > 0.05). Diets containing NIT reduced CH₄ emissions by 27% (g/d) and yield by 21% (g/kg DMI) compared to the CTR (P < 0.05). The pH values and total volatile fatty acids (VFA) concentration did not differ between dietary treatments (P > 0.05) but differed with time, and post-feeding (P < 0.05). Increases in the concentrations of ruminal ammonia nitrogen (NH₃–N) and acetate were observed, whereas propionate decreased at 4 h post-feeding with the NIT diet (P < 0.05). Feeding the NIT diet reduced the populations of total bacteria, total methanogens, Ruminococcus albus and Ruminococcus flavefaciens, and the abundance of Succiniclasticum, Coprococcus, Treponema, Shuttlewortia, Succinivibrio, Sharpea, Pseudobutyrivibrio, and Selenomona (P < 0.05); whereas, the population of total fungi, protozoa, Fibrobacter succinogenes, Atopobium and Erysipelotrichaceae L7A_E11 increased (P < 0.05). In conclusion, feeding nitrate reduces enteric CH₄ emissions and the methanogens population, whereas it decreases the propionate concentration and the abundance of bacteria involved in the succinate and acrylate pathways. Despite the altered fermentation profile and ruminal microbiota, DMI was not influenced by dietary nitrate. These findings suggest that nitrate has a predominantly direct effect on the reduction of methanogenesis and propionate synthesis.     

Milk Production in Sows after Spontaneous Delivery and after Delivery Induced by PGF2α Analogs

In this study the amount of milk produced during the first week of lactation was compared in sows with induced parturition and sows which delivered spontaneously (with special attention to sows showing MMA symptoms). Fifteen sows (L X LW) were used from a pig farm in which MMA was seen in 20 to 25% of all farrowings. The animals were divided into three groups of 5 each. Group A and B were treated with two different PGF ₂ α analogs (2 mg of alfaprostol or 0.45 mg of tiaprost) on 111 day of pregnancy, and group C (control) with 2 ml of saline solution. Treatment with PGF analogs induced parturitions 24 to 30 h later, controls delivered spontaneously on day 114. Litters were equalized to nine piglets per sow. The milk yield of each sow was calculate using the method of weighing piglets before and after each suckling. Piglets were allowed to suckle 12 times in the first 24 h after parturition, then 8 or 9 times in the next 24 h and from 48 h onwards 8 times during 24 h, until the end of the 7 day observation period. During the first day after parturition the control group appeared to produce slightly more milk than groups A and B whereas from 24 to 48 h, milk yields decreased in all animals. From 48 onwards milk production increased in all groups. Between 72–96 h, two sows of the control group showed symptoms of MMA and their piglets developed diarrhea. Microbiological analysis confirmed the presence of haemolytic Streptococci. The lactation curves of treated and untreated sows with no signs of MMA were very similar; the pattern was more erratic in sows with MMA. The total milk yields during the first week of lactation did not differ between groups; there were no significative difference in the weight gain of the piglets in groups A, B and C. The difference recorded in milk yield and release patterns between sows with or without MMA opens new aspects with regard to the aetiology of a syndrome that not only involves the sows health, but produces intestinals disease in their piglets.     

Time lag between peak concentrations of plasma and salivary cortisol following a stressful procedure in dairy cattle

Background

Measurement of salivary cortisol has been used extensively as a non-invasive alternative to blood sampling to assess adrenal activity in ruminants. However, there is evidence suggesting a considerable delay in the transfer of cortisol from plasma into saliva. Previous studies in cattle have used long sampling intervals making it difficult to characterise the relationship between plasma and salivary cortisol (PLCort and SACort, respectively) concentrations at different time points and determine whether or not such a time lag exist in large ruminants. Therefore, the objective of this study was to characterise the relationship between plasma and salivary cortisol and determine if there is a significant time lag between reaching peak cortisol concentrations in plasma and saliva across a 4.25 h time-period, using short sampling intervals of 10–15 min, following social separation in dairy cattle.Five cows were separated from their calves at 4 days after calving, and six calves were separated from a group of four peers at 8 weeks of age. Following separation, the animals were moved to an unfamiliar surrounding where they could not see their calves or pen mates. The animals were catheterised with indwelling jugular catheters 1 day before sampling. Blood and saliva samples were obtained simultaneously before and after separation.

Results

In response to the stressors, PLCort and SACort increased reaching peak concentrations 10 and 20 min after separation, respectively. This suggested a 10 min time lag between peak cortisol concentrations in plasma and saliva, which was further confirmed with a time-series analysis. Considering the 10 min time lag, SACort was strongly correlated with PLCort (P < 0.0001).

Conclusions

Salivary cortisol correlates well with plasma cortisol and is a good indicator of the time-dependent variations in cortisol concentrations in plasma following acute stress. However, there is a time lag to reach peak cortisol concentrations in saliva compared to those in plasma, which should be considered when saliva samples are used as the only measure of hypothalamic-pituitary-adrenal axis response to stress in cattle.     

Effects of Lactobacillus plantarum on the intestinal morphology,intestinal barrier function and microbiota composition of suckling piglets

This study investigated the effect of Lactobacillus plantarum strain 299v on gut health in suckling piglets. Sixty newborn piglets were assigned to control and probiotic treatments, with three litters per treatment (ten piglets/litter). From days 1 to 20 of life, piglets were orally administered a placebo of 0.1% peptone or 1.0 ×  10¹⁰ CFU L. plantarum 299v daily. Six piglets per treatment were sacrificed on day 20, and intestinal tissues (including duodenum, jejunum, ileum and colon) and the intestinal contents from colon segments were collected. The results demonstrated that piglets treated with L. plantarum 299v had a lower diarrhoea incidence than the controls. L. plantarum 299v administration significantly increased the ratio of the villus height to the crypt depth in the jejunum and ileum, as well as the mRNA expression of jejunal occludin and ileal zonula occludens 1 (ZO‐1). The L. plantarum treatment also increased the mRNA abundance of porcine β‐defensin 2 (pBD2) and pBD3 in the jejunum and ileum and of toll‐like receptors (TLRs), such as TLR2, TLR4, TLR6 and TLR9 in the ileum, and significantly upregulated the mRNA abundances of ileal pBD1 and colonic TLR4. Additionally, the L. plantarum 299v treatment significantly changed the structure of the colonic microbiota, as evidenced by the obvious increases in the relative abundances of the phyla Firmicutes and Actinobacteria and of the genus Lactobacillus. Our findings indicate that L. plantarum 299v facilitates the gut health of suckling piglets, probably by improving the intestinal morphology and intestinal barrier function and by modifying the structure of the gut microbiota.