氨基酸与母猪营养

母猪饲养是养猪生产中最重要的环节之一。母猪的营养尤其是蛋白质和氨基酸营养不仅直接影响仔猪的生长性能,而且也对母猪的使用年限和繁殖性能会产生很大影响。母猪蛋白质及氨基酸营养受品种、胎次、母猪体况、产仔数、泌乳量、采食量、哺乳期长短等诸多因素影响,增大了母猪氨基酸营养的研究难度。同时母猪个体较大、研究成本高、试验群体偏小、数据采集困难以及试验误差较大等问题也限制了母猪蛋白质及氨基酸营养的系统研究。本文对母猪的氨基酸营养进行综述,旨在为养猪生产实践中母猪日粮的合理配制提供参考。     

日粮色氨酸水平对仔猪生产性能和血液生化指标影响的研究

在赖氨酸/蛋氨酸+胱氨酸/苏氨酸/异亮氨酸比例为100:68:65:59的玉米—玉米蛋白粉基础日粮中,添加合成的 L-色氨酸构成5种色氨酸(TRP)水平的日粮(TRP 水平分别为0.125%、0.155%、0.180%、0.215%和0.24%)。将35头太湖母猪与长白公猪的杂交仔猪在35日龄断奶时,随机分为5组,分别饲喂上述为同 TRP 水平的日粮,饲养期长达30天。结果表明,日粮(TRP)水平显著影响仔猪的日均耗料量(ADFI)、日均增重(ADG)和饲料转化率(FCR)。TRP 水平为0.215%时,仔猪生长性能最好。TRP 水平为0.24%时仔猪的生长性能与0.215%时差异不显著(P>0.05)。TRP 水平在0.125%～0.215%范围内,仔猪 ADG、ADFI 与 TRP 水平呈正相关,回归方程分别为:ADG(g)=2.57 TRP(mg/kg)-80.21,(r=0.99,P<0.01);ADFI(g)=2.49 TRP(mg/kg)+220.31,(r=0.95,P>0.05);FCR 与日粮 TRP 水平呈显著负相关,回归方程为:FCR=2.877-5.668 TRP(%),(r=0.945,P<0.01).血清尿素氮(SUN)含量与日粮 TRP 水平呈负相关,回归方程为 SUN=19.47-34.35TRP(%),(r=0.95,P<0.05)。从仔猪生长性能和 SUN 两项指标确定 TRP 在理想氨基酸模式中的相应值分别为18和20。在 TRP 水平0.125%～0.215%范围内,血清碱性磷酸酶活性与 TRP 水平呈现正相关,在0.215%时最高;TRP 水平在0.24%时与0.215%时差异不显著(P>0.05)。日粮 TRP 水平对血清谷丙转氨酶(GPT)和谷草转氨酶(GOT)活性无显著影响(P>0.05)。日粮 TRP 水平对血清总蛋白含量无显著影响,而血清蛋白含量随 TRP 水平升高而增加,在0.215%时最高。血清蛋白质系数(A/G)在各 TRP 水平间有显著差异(P<0.05),日粮中 TRP 含量在0.125%时,A/G显著降低(P<0.05),A/G 在 TRP 水平为0.215%时最高,TRP 在0.125%～0.215%之间,A/G 呈现线性递增,回归方程为:A/G=9.34TRP(%)+0.956,r=0.98,P<0.05),而 TRP 水平为0.24%与0.215%的两组 A/G 无显著差异(P>0.05)。     

Effects of dietary tryptophan and stocking density on the performance,meat quality,and metabolic status of broilers

Background

Highly automated cage-rearing systems are becoming increasingly popular in China. However, a high stocking density can cause oxidative stress and decrease broiler performance. The tryptophan (TRP) derivative 5-hydroxytryptophan (5-HT) has been shown to preserve membrane fluidity in birds suffering from oxidative stress. Therefore, this experiment was conducted to determine the effects of dietary TRP supplementation on performance, breast meat quality and oxidative stress in broilers reared in cages with a high or low stocking density.

Methods

Female Arbor Acres broilers (25-d-old, n = 144) were randomly allocated to 1 of 4 treatments. The birds were fed a diet based on corn, soybean meal, cottonseed meal and corn gluten meal containing either 0.18 or 0.27% TRP and were housed with stocking densities of 11 or 15.4 birds/m² in a 2 × 2 factorial experiment. Broiler performance was evaluated from d 25 to 42. Eight birds from each treatment were slaughtered on d 42 and plasma and breast muscle samples were collected to measure biochemical indices.

Results

A higher stocking density tended to be associated with reduced weight gain (P < 0.10), and significantly increased plasma glutamic-pyruvic transaminase (GPT) activity (P < 0.001). Increased dietary TRP significantly reduced the activities of lactic dehydrogenase and GPT while increasing total cholesterol in the plasma (P < 0.01), reducing drip loss of breast muscle (P < 0.10) and improving feed efficiency (P < 0.10).

Conclusions

An increase in dietary TRP, 1.5-fold higher than the standard supplementation level, can alleviate oxidative stress as well as improve welfare and feed efficiency in broilers reared in cages with a high stocking density.     

The effect of dietary tryptophan levels on oxidative stress of liver induced by diquat in weaned piglets

Oxidative stress can induce abnormal tryptophan metabolism. The present study was mainly conducted to determine the effect of dietary tryptophan levels on oxidative stress in the liver of weaned pigs challenged by diquat. A total of 36 PIC piglets weaned at 21 days of age were randomly allotted to 1 of 3 diets containing dietary tryptophan levels of 0.18, 0.30, and 0.45% for 14 d. On day 8, the piglets were injected intraperitoneally with sterile 0.9% NaCl solution or diquat (10 mg/kg body weight). During the first 7 d of trial, increasing dietary tryptophan levels enhanced average daily gain (P = 0.09) and average daily feed intake (P = 0.08), and decreased the feed efficiency (P < 0.05) of piglets. The growth performance was decreased by diquat injection (P < 0.05). Diquat injection also decreased the activities of the superoxide dismutase (SOD) and glutathione peroxidase (GPx) in the plasma and liver (P < 0.05), increased plasma malondialdehyde (MDA) (P < 0.05) and urea nitrogen (P < 0.05) concentrations, and enhanced MDA concentration (P = 0.09) and tryptophan 2,3-dioxygenase (TDO) activity (P = 0.07) in liver of piglets. Increasing dietary tryptophan levels could attenuate the effects of diquat injection on the MDA (P = 0.06) concentration and the activities of SOD (P = 0.09) and GPx (P = 0.05) of the liver, and plasma urea nitrogen (P = 0.06) concentration in the piglet. There was a synergistic role for increasing TDO activity in the liver between dietary tryptophan levels and diquat injection (P < 0.05). These results suggest that increasing dietary tryptophan levels could attenuate the oxidative stress of the liver in weaned piglets intraperitoneally injected with diquat via enhancing the antioxidant capacity.     

日粮色氨酸水平对生长猪的氮利用效率、血浆类胰岛素生长因子-I、生长激素及胰岛素的影响

本试验旨在研究日粮色氨酸水平对生长猪的氮利用率以及对血浆类胰岛素生长因子-I(IGF-I)、生长激素(GH)、胰岛素浓度的影响。试验以4头大白去势公猪作为试验动物,以色氨酸含量分别为1.2、1.7、2.2和2.7g/kg的4种日粮为试验处理,按照4×4拉丁方进行试验设计。结果表明,色氨酸水平对干物质消化率、有机物消化率和氮消化率没有显著性影响(P>0.05)。氮沉积和氮的生物学利用率随着日粮色氨酸水平由1.2提高到1.7、2.2和2.7g/kg而显著提高(P<0.05),但是试验处理1.7、2.2和2.7g/kg之间的氮沉积和氮的生物学价值没有显著差异(P>0.05)。不同处理之间的血浆IGF-I、GH和胰岛素浓度没有显著差异(P>0.05)。日粮色氨酸水平和血浆IGF-I、GH或胰岛素浓度之间以及氮沉积和血浆IGF-I、GH或胰岛素浓度之间均无显著的相关关系(P>0.05)。综合以上结果,日粮色氨酸水平对生长猪的氮沉积具有显著影响,而对血浆IGF-I、GH和胰岛素没有显著影响。     

Enriched production of N-hydroxycinnamic acid amides and biogenic amines in pepper (Capsicum annuum) flowers

The biosynthesis of N-hydroxycinnamic acid amides (HCAAs), such as feruloyltyramine, p-coumaroyltyramine, feruloylserotonin, and p-coumaroylserotonin, in pepper plants was investigated in view of the activity of their corresponding enzymes and substrate levels. Almost all HCAAs were found in flowers, whereas the enzyme activity essential for HCAA biosynthesis seemed to be expressed constitutively in all tissues tested. The highest levels of the biogenic amines tyramine and serotonin, the key amine substrates, were also found in flowers, indirectly suggesting that the amine substrates play an important regulatory role in the synthesis of HCAAs.     

Effect of magnesium sulphate and l-tryptophan and genotype on the feed intake, behaviour and meat quality of pigs

Sixty-nine entire male pigs with different halothane genotype (homozygous halothane positive — nn-, n = 36; and homozygous halothane negative — NN-, n = 33) were fed with a supplementation of magnesium sulphate (Mg) and/or l-tryptophan (Trp) in the diet for 5 days before slaughter. Animals were housed individually and were submitted to stressful ante mortem conditions (mixed in the lorry according to treatments and transported 1 h on rough roads). Individual feed intake was recorded during the 5-d treatment. At the abattoir, pig behaviour was assessed in the raceway to the stunning system and during the stunning period by exposure to CO₂. Muscle pH, colour, water holding capacity, texture and cathepsin activities were determined to assess meat quality. The number of pigs with an individual feed intake lower than 2 kg/day was significantly different among diets (P < 0.05; Control: 8.7%; Mg&Trp: 43.5%; Trp: 17.4%) and they were considered to have inadequate supplement intake. During the ante mortem period, 15.2% of pigs included in the experiment died, and this percentage decreased to 8.7% in those pigs with a feed intake > 2 kg/day, all of them from the stress-sensitive pigs (nn). In general, no differences were observed in the behaviour of pigs along the corridor leading to the stunning system and inside the CO₂ stunning system. During the stunning procedure, Trp diet showed shorter periods of muscular excitation than control and Mg&Trp diets. The combination of a stressful ante mortem treatment and Mg&Trp supplementation led to carcasses with high incidence of severe skin lesions. Different meat quality results were found when considering all pigs or considering only those with adequate supplement intake. In this later case, Trp increased pH₄₅ (6.15) vs Control diet (5.96) in the Longissimus thoracis (LT) muscle (P < 0.05) and pH at 24 h (Trp: 5.59 vs C: 5.47) led to a higher incidence of dark, firm and exudative (DFD) traits in SM muscle (P < 0.05). Genotype affected negatively all the meat quality traits. Seventy-five percent of LT and 60.0% of the SM muscles from nn pigs were classified as pale, soft and exudative (PSE), while none of the NN pigs showed these traits (P < 0.0001). No significant differences were found between genotypes on the incidence of DFD meat.Due to the negative effects observed in the Mg&Trp group in feed intake and carcass quality, the utilization of a mixture of magnesium sulphate and tryptophan is not recommended.     

3～6周肉仔鸡苏氨酸、色氨酸需要量的研究

本试验研究 3～ 6周肉仔鸡苏氨酸 (Thr)和色氨酸 (Trp)的需要量。Thr和Trp各设四个水平 ,日粮总Thr的含量为 0 .66%、0 .70 %、0 .74 %和 0 .78%,真可消化Thr的含量为 0 .57%、0 .61 %、0 .65%和0 .69%;日粮总Trp的含量为 0 .1 7%、0 .1 8%、0 .1 9%和 0 .2 0 %,真可消化Trp的含量为 0 .1 5%、0 .1 6%、0 .1 7%和 0 .1 8%。采用两因子完全随机设计。对体增重、饲料转化率、氮表观存留率和血清尿酸浓度等指标进行了测定。结果表明 :3～ 6周肉仔鸡粗蛋白水平降到 1 8%仍有较好的饲养效果 ;Thr和Trp间存在交互作用 ,且对体增重和饲料转化率有显著影响 ;综合考虑各项指标 ,日粮总Thr和Trp的需要量为0 .66%和 0 .1 8%～ 0 .1 9%,真可消化Thr和Trp的需要量为 0 .57%和 0 .1 6%～ 0 .1 7%。     

马蓝色氨酸合成酶基因的克隆、序列及表达分析

通过对马蓝转录组数据分析,从马蓝叶片cDNA中克隆得到了色氨酸合成酶基因完整的编码序列(CDS),长度为807 bp,命名为BcTSA(GenBank登录号:MG857654),可编码269个氨基酸,并对其蛋白质理化性质、结构域、跨膜区、信号肽、磷酸化位点、糖基化位点、编码蛋白的二、三级结构、亚细胞定位进行了分析。蛋白序列多重比对结果显示与其他植物的TSA蛋白序列具有一定的同源性,并通过qRT-PCR法检测BcTSA基因在不同器官的表达与外源激素茉莉酸甲酯(MeJA)、脱落酸(ABA)、水杨酸(SA)诱导表达情况。推测其编码的蛋白为亲水蛋白,相对分子质量为28.9 kD,理论等电点(pI)为5.65,无跨膜区;亚细胞定位分析结果显示,BcTSA定位在叶绿体中的可能性大,没有信号肽;有18个磷酸化位点,存在6个潜在的糖基化位点,二级结构主要由α-螺旋构成;BcTSA氨基酸序列与其它15种物种氨基酸序列的保守区域达到81.35%的相似性;BcTSA基因在马蓝不同组织中均有表达,在叶中的表达量最高,根中最低;另外,发现BcTSA基因响应外源诱导子对代谢的调控。BcTSA基因的克隆与序列分析,有助于研究BcTSA基因的功能,对提高马蓝有效成分的含量具有重要意义。