Effect of recombinant porcine somatotropin on growth and carcass quality in growing pigs: interactions with genotype, gender and slaughter weight

Effects of recombinant porcine somatotropin (rpST) on growth, lean tissue growth, feed intake, feed conversion, lean tissue feed conversion, backfat thickness and lean percentage were examined in 96 growing pigs. The experiment used barrows and gilts from the genotypes Duroc, F1 (Dutch Yorkshire x Dutch Landrace) and Pietrain. Half the pigs received 14 mg rpST i.m. twice each week starting at 60 kg; others received a placebo. Pigs had ad libitum access to a diet containing 2,162 kcal net energy and 182 g crude protein per kilogram and were slaughtered at either 100 or 140 kg live weight. From 60 to 100 and from 100 to 140 kg, live weight responses to rpST averaged as follows: daily gain, +4.5 and +19.9%; feed intake, -4.4 and +3.5%; feed conversion, -8.4 and -13.9%; backfat thickness, -13.8 and -22.8%; lean percentage, +4.4 and +8.7%; lean tissue growth rate, +8.6 and +35.8%; and lean tissue feed conversion, -13.1 and -24.9%. No gender x rpST interaction was detected. However, a genotype x treatment interaction was significant for backfat thickness at both slaughter weights, showing a higher response to rpST in Duroc than in Pietrain and F1. Growth performance was improved more by rpST in F1 and Pietrain than in Duroc, especially at higher weights, but carcass traits were improved more by rpST in Duroc. The response to rpST in lean tissue growth rate from 60 to 100 kg was highest in fatter animals (Duroc, barrows), whereas from 100 to 140 kg, response in lean tissue growth rate to rpST was highest in leaner animals (Pietrain, F1, gilts).     

梅山猪与西方猪生长性能和胴体特性的比较研究

综述了梅山猪与西方猪生长性能和胴体特性的比较研究.结果表明梅山猪主要以生长性能差和脂肪组织高度发育为特性,梅山猪与西方猪相比,具有显著较低的日增重、采食量和瘦肉组织百分率以及较高的饲料转化率和背膘厚度,但梅山猪的肉质优于欧洲猪的.     

Recombinant porcine somatotropin alters performance and carcass characteristics of heavyweight swine and swine fed alternative feedstuffs

The efficacy of recombinantly derived porcine somatotropin (rpST) in improving the performance and carcass characteristics of heavyweight finishing pigs was determined. In Study 1, 36 pigs were killed for determination of initial carcass composition at 102 kg, and 36 pigs each were given 0, 1.5, 3, 6, or 9 mg of rpST/d from 102 to 136 kg live weight. Corn-soybean meal diets fed contained 19.8% CP and greater than 1% lysine. Study 2 tested the effects of 3 mg/d on pigs for 4 wk from 84 kg BW fed a corn-soybean meal or a triticale-barley-peas diet. Performance variables (ADG, average daily feed intake [ADFI], and feed efficiency [FE]) were measured weekly. Treatment with rpST increased (P less than .01) ADG and FE and decreased (P less than .01) ADFI in both studies. In Study 1, leaf fat, backfat thickness, belly thickness, and carcass fat were all decreased (P less than .01) linearly by rpST. Loin eye area (LEA), total trimmed lean, and total protein content were increased quadratically (P less than .01). At the 3-mg dose, ADFI, ADG, and FE were 87, 130, and 137% of control, and LEA, backfat, total protein gain, and total fat gain were 107, 80, 136, and 52% of control. Loin eye area was not increased (P greater than .05) in the pigs in Study 2; however, backfat thickness was reduced 16% by rpST (P less than .01). The effects of rpST were the same on both dietary regimens (P greater than .05). These studies demonstrate the effectiveness of rpST in increasing ADG and carcass leanness and improving FE in heavyweight pigs and in pigs fed alternative feedstuffs.     

Effect of ractopamine on growth, carcass traits, and fasting heat production of U.S. contemporary crossbred and Chinese Meishan pure- and crossbred pigs.

Twenty-four U.S. crossbred (Duroc x White composite; D x Wc; 83.9 kg), 24 purebred Meishan (M; 59.4 kg), and 24 Meishan x White composite crossbred (M x Wc; 83.4 kg) barrows were allotted within genotype to a 16% CP corn-soybean meal diet or this basal diet + 20 ppm of ractopamine and allowed ad libitum access to feed for 52 d. No genotype x ractopamine interactions were detected (P greater than .05) in pigs for growth, lean cuts, ham and loin characteristics, leaf fat and visceral organ weights, fasting whole-animal heat production, and carcass traits except longissimus muscle area (LMA). The LMA was increased by ractopamine in D x Wc and M x Wc pigs (P less than .05) but not in M pigs. Compared with D x Wc and M x Wc pigs, M pigs had lower ADG, ADFI, and gain to feed ratio (G/F), shorter carcasses, and lower dressing percentage, LMA, predicted amount of muscle, weights of trimmed picnic, loin, and ham cuts, percentage of ham lean, and CP in ham lean, but heavier liver, kidneys, pancreas, and entire gastrointestinal tract with greater percentage of ham fat and ham bone (P less than .05). The M x Wc pigs had lower ADG, G/F, dressing percentage, LMA, amount of muscle, weights of trimmed cuts, and percentage of ham lean but heavier lungs, pancreas, stomach, and large intestine than did D x Wc pigs (P less than .05). Supplemental ractopamine increased ADG, G/F, dressing percentage, amount of muscle, trimmed loin weight, percentage of ham lean, and CP in ham lean and decreased weights of heart, lungs, kidneys, and pancreas in pigs (P less than .05). Neither genotype nor ractopamine had any effect on 4- to 24-h postprandial whole-animal heat production of pigs (P greater than .05). These results indicate that ractopamine will improve growth performance and carcass leanness in pure- and crossbred Meishan pigs.     

含不同比例梅山猪血缘杂交肉猪胴体品质研究

选不同比例梅山猪血缘 (梅山猪血缘比例为 0 ,1 / 8,1 / 4 ,3 / 8,1 / 2 ,1 )的杂交仔猪 68头 ,采用单因子试验设计 ,在同一营养水平 (DE :前期 1 4.2 1兆焦 /千克 ,后期 1 3 .79兆焦 /千克 ;CP :1 5 % ,1 3 % ;Lys:0 .75 % ,0 .65 % )下 ,研究不同梅山猪血缘比例对不同体重阶段生长肥育猪胴体品质 (平均膘厚、眼肌面积、瘦肉率等 )的影响。结果表明 :梅山猪与国外猪种杂交后 ,1 / 2梅山 ,1 / 4梅山 ,1 / 8梅山杂交猪的胴体品质显著高于 (P <0 .0 1 )纯种梅山猪。在同一体重下 (1 1 0kg) ,3 / 8梅山 ,1 / 2梅山和纯种梅山猪的平均膘厚显著高于其它血缘组 (P <0 .0 1 ) ,1 / 8梅山 ,1 / 4梅山和杜×大杂交猪间差异不显著 (P >0 .0 5 ) ;瘦肉率和眼肌面积随梅山猪血缘比例增加 ,逐渐下降 ;同一血缘不同体重阶段生长肥育猪随体重 (或饲养天数 )增加 ,平均膘厚、眼肌面积、瘦肉率呈显著二次曲线变化 (P <0 .0 1 ) ,肥育猪在适宜体重下屠宰 ,改善胴体品质     

长白×北京黑F_1代猪适宜粗蛋白与赖氨酸、粗蛋白比的研究

用2个蛋白水平和2个赖蛋比值作2×2析因设计,将32头始重25公斤的长白×北黑F_1代猪随机分成4组,每组8头,进行饲养试验;将16头阉公猪也分为4组,每组4头,进行N—平衡试验,研究了以玉米—豆饼为基础的饲粮蛋白质和赖蛋比水平对猪在20—60公斤和60—90公斤两个体重阶段的生产性能,氮沉积和90公斤时胴体品质的影响。粗蛋白由16—14％降至14—12％时极显著降低了胴体瘦肉率、背最长肌蛋白含量和日氮沉积量,提高了背膘厚,对增重和饲料效率等无明显影响。赖蛋比4.5—4.5％提高到5.0—4.5％,除降低 日采食量、增重和屠宰率(P<0.05)外,对其余指标均无影响。本试验结果表明:长×北F_1代瘦肉猪饲粮适宜粗蛋白为16—14％,赖蛋比为4.5—4.5％。     

Evaluation of recombinant porcine somatotropin on growth performance, carcass characteristics, meat quality, and muscle biochemical properties of Belgian Landrace pigs.

The dose related effects of recombinant porcine somatotropin (rpST) on growth, carcass characteristics, muscle properties, and meat quality were investigated in lean Belgian Landrace finishing pigs. Ninety-six pigs (48 barrows and 48 gilts) were injected daily with either vehicle, 1.5, 3, or 6 mg of rpST from 60 to 97.5 kg live weight. Each treatment group consisted of six pens of four pigs each (two of each sex). Pigs were given ad libitum access to a high-protein (20.4% CP) cereal-based diet. Administration of rpST increased (P less than .05) growth rate (16.3 to 25.4%) and improved (P less than .05) feed efficiency (16.9 to 29.4%). Feed consumption was reduced (12%; P less than .05) only in the 6 mg of rpST group. Liver, kidney, and heart weights were increased (P less than .05) in the 3 and 6 mg of rpST groups. Although the Belgian Landrace pigs are bred for superior carcass quality, rpST further improved (P less than .05) carcass composition at all dose levels as evidenced by a reduction (10 to 50%) in a number of subcutaneous fat depth measurements, an increase (10 to 20%) in longissimus muscle area, and an improvement in the lean cut:fat cut ratio. Rate of pH decline in the gluteus and longissimus muscles was similar, but rapid, in all groups (pH after 30 min = 5.74 to 5.94); the ultimate (24 or 72 h) pH was .15 to .2 pH units higher (P less than .05) in the pigs that received the 3 and 6 mg of rpST doses.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of dietary protein and recombinant porcine somatotropin administration in young pigs: growth, body composition and hormone status

The influence of dietary protein and recombinant porcine somatotropin (rpST) administration on growth and body composition was investigated in barrows. Ten groups of six pigs starting at 30 kg were restrictively fed (approximately 80% of ad libitum) one of five diets containing 11, 15, 19, 23 or 27% protein. Diets contained skim milk (12%). Soybean meal diluted with cornstarch was used as the supplemental source of dietary protein. Diets were isocaloric (3.8 Mcal DE/kg) and all contained the same amount of lysine (18 to 20 g/kg). Thirty pigs were treated daily with rpST (100 micrograms/kg) by i.m. injection; the remaining pigs were treated with sterile diluent (control) for 42 d. Growth rate was greater in rpST-treated pigs at all levels of protein intake; however, the magnitude of the response to rpST treatment was lowest among pigs fed the diet containing 11% protein. Feed:gain ratio, backfat depth and carcass fat content were decreased in rpST-treated pigs compared to respective controls. Additionally, the concentration of carcass fat decreased concomitantly with an increase in dietary protein intake. Concentration of carcass protein increased linearly as dietary protein increased in control and rpST-treated pigs. In contrast, treatment with rpST was associated with an increased visceral mass; the concentration of protein and fat in the viscera was influenced by protein intake but not by rpST. These results, characterized by few treatment interactions, suggest that when energy intake is kept constant and appropriately fed pigs serve as controls, dietary protein and rpST influence growth and body composition by independent mechanisms.(ABSTRACT TRUNCATED AT 250 WORDS)     

放牧对松辽黑猪生长肥育及胴体肉质的影响

选择松辽黑生长育成猪200头,分成舍饲组和林地放牧组,进行饲养育肥性能测定。舍饲组按常规全期饲喂全价配合精饲料;放牧组则先在舍内育成至体重达40kg后,白天林地放牧,早晚各补饲一次精饲料,直至达到育肥体重。饲养试验结束,各饲养组选取4头(2公2母)体重100kg左右的试验猪,进行屠宰做胴体肉质测定。结果表明:日增重舍饲组为736.5g,放牧组为467.5g,差异极显著(<0.01),而放牧组则每增重1kg比舍饲组少耗精饲料730g,差异显著(<0.05)。屠宰率放牧组为70.71%,比舍饲组的69.21%高,差异显著(<0.05),肌内脂肪含量放牧组为4.92%,舍饲组为3.60%,差异显著(<0.05),其它胴体肉质指标如眼肌面积、背膘厚、瘦肉率及肉色、pH、失水率、嫩度等,两种饲养方式,差异均不明显,但放牧饲养组要比舍饲组有改善和提高的趋势。     

维生素A水平对生长猪生产性能、肝脏维生素A含量和血清免疫参数的影响

试验研究饲粮添加不同水平维生素A(VA) (0、1300、2600、5000、10000、15000IU/kg)对22 -50kg生长猪生产性能、胴体品质、胴体无脂瘦肉增重、肝脏和血浆中VA含量、血清免疫参数的影响。结果表明 ,添加VA1300 -10000IU/kg 提高了日增重 (P>0.05)、极显著地降低料重比 (P<0.01) ;但VA添加水平从1300IU/kg增加至10000IU/kg,料重比显著提高 (P<0.05) ,采食量也极显著提高 (P<0.01)。各组屠宰率、瘦肉率、脂肪率、背膘厚、胴体瘦肉成分都无显著差异 (P>0.05) ,眼肌面积则随VA水平的升高而趋于增大(P>0.05)。胴体瘦肉和无脂瘦肉日增重在添加VA1300IU/kg 和10000IU/kg两组间很接近 ,而且优于其它组 (P<0.05)。随着VA水平的提高 ,肝脏中VA含量极显著提高 (P<0.01) ,至添加VA10000IU/kg组最高 ,之后略下降 ;添加VA有使血浆中VA含量升高的趋势 (P>0.05)。各组血清中IgG、IgA、IgM含量都无显著差异 (P>0.05) ,添加VA使T淋巴细胞中CD3+ 和CD8+ 亚群比例趋于升高 (P>0.05),随着添加VA水平提高 ,血清T淋巴细胞中CD4+/CD8+比值趋于下降 ,至添加VA10000IU/kg 组最低 ,在VA15000IU/kg 组又明显上升 (P>0.05)。以肝脏中VA含量为指标 ,生长猪VA适宜水平为在基础饲料上添加10000IU/kg ,但根据生产性能等其它指标 ,添加1300IU     

The feeding of ad libitum dietary protein to organic growing-finishing pigs

The effects of three dietary protein levels on growth, meat, and carcass traits were studied in organic pigs fed a three-phase diet. Assuming lysine was the first limiting amino acid, feeds were formulated to ileal digestible (ID) lysine content, with the ID lysine:crude protein ratio set at a constant of 4%. Feeds were also formulated to an isocaloric rate (net energy: 9.4 MJ/kg during the first feeding phase, 9.25 MJ/kg during the second feeding phase and 9.1 MJ/kg during the finisher phase), with a high (HP), a medium (MP) or a low (LP) protein content ranging from 20% to 14% crude protein (CP). ID lysine content of the LP and MP feed was, respectively, 80% and 90% of the ID lysine content of the HP feed. The nutrient formulation of the HP feed was similar to nutrient levels commonly used in conventional Belgian pig farming. From 20 to 40 kg liveweight, the pigs showed better feed conversion ratios, with an increasing dietary protein concentration (r(2)=0.84). This effect was not observed in the second and third phases, although a significant effect of protein concentration on voluntary feed intake in the second phase did occur (P=0.018), probably as a compensation for the lower protein concentration in the LP diet. Analysis of the carcasses showed a lower meat percentage with lower protein concentration (P<0.05), whereas influences on meat quality were limited. It was concluded that whereas during the first phase of growth, higher protein concentration leads to better performance, from the second phase onwards (45 kg), at least with isocaloric diets, a decrease in protein content (corresponding to a 10% reduction in dietary ID lysine levels compared to conventional pig fattening) may be used in organic growing-finishing pig nutrition.     

Influence of dietary protein and recombinant porcine somatotropin administration in young pigs: II. Accretion rates of protein, collagen, and fat.

The present study was conducted to determine the effects of different dietary protein levels and recombinant porcine somatotropin (rpST) administration on deposition rates of protein, fat, water, ash, and collagen in pigs. Ten groups of six barrows (30 kg BW) were restrictively fed (80% of ad libitum) one of five diets containing 11, 15, 19, 23, or 27% CP. Diets were isoenergetic and all contained equivalent amounts of lysine. Thirty barrows were treated daily with rpST (100 micrograms/kg) by i.m. injection; remaining pigs were treated with diluent for 42 d. At all levels of dietary protein intake, carcass and empty body accretion rates of protein, water, and ash were greater in rpST-treated pigs than in respective controls. The magnitude of change elicited by rpST was lowest in pigs consuming 11% CP. Administration of rpST resulted in a 34% decrease in the accretion rate of fat; increasing protein intake resulted in a linear decrease in fat accretion in control and rpST-treated pigs. Accretion rates of protein, water, ash, and fat were increased in viscera of rpST-treated pigs compared with respective controls; rates of visceral protein and water accretion were increased as dietary protein was increased, whereas deposition of fat was decreased in control and rpST-treated pigs. Administration of rpST resulted in an overall 66% increase in the utilization efficiency of dietary protein for empty body protein deposition. Protein intake had minimal effect on the concentration of collagen in the carcass; however, rpST treatment increased concentrations of total and soluble collagen by 30 and 33%, respectively. Recombinant pST had little influence on collagen crosslinking or maturation. Deposition rate of carcass collagen was increased 63% in rpST-treated pigs compared with respective controls.     

Effects of ractopamine on genetically obese and lean pigs

Twenty-eight genetically obese and 24 lean barrows (65.0 and 68.7 kg average BW, respectively) were allotted within genotype to a 16% CP corn-soybean meal basal diet or this basal diet + 20 ppm ractopamine (a phenethanolamine beta-adrenergic agonist) and allowed ad libitum access to feed for 48 d. Compared to lean pigs, obese pigs had lower ADG, gain to feed ratio, longissimus muscle area, predicted amount of muscle, and weights of trimmed loin and ham, ham lean, heart, spleen, kidney and gastrointestinal tract (P less than .05). Obese pigs also had shorter carcass but higher dressing percentage, backfat thickness, fat depth, fat area, untrimmed loin weight and fasting plasma urea N concentration (P less than .05). Dietary supplementation with 20 ppm ractopamine reduced daily feed intake and improved gain to feed ratio in both lean and obese pigs (P less than .05). Pigs fed ractopamine had shorter carcasses, less fat depth and fat area, smaller weights of stomach and colon plus rectum, but higher dressing percentages, longissimus muscle areas, weights of trimmed Boston butts, picnics and loins, ham lean and predicted amounts of muscle than pigs not fed ractopamine (P less than .05). Supplemental ractopamine had no effect on fasting plasma concentrations of urea N, nonesterified fatty acids, triglyceride or glucose (P greater than .05). No genotype x ractopamine interactions for the criteria described above were detected (P greater than .05). These results suggest that ractopamine will improve the efficiency of feed utilization and carcass leanness in swine with different propensities for body fat deposition.     

Effect of recombinant porcine somatotropin on energy and protein utilization by growing pigs: interaction with capacity for lean tissue growth.

Three litters of four pigs from each of four different groups were used to evaluate the effect of porcine somatotropin (pST) on growth performance, body gain composition, energy and N metabolism, and in vitro cytochrome oxydase (final enzyme of the respiratory chain) activity of tissues. The four groups included boars from a synthetic line (SG1) or the Large White breed (SG2) and barrows from the Large White breed (SG3) or crossbred between Large White and Meishan breeds (SG4). Inherent capacity for daily lean tissue growth (LTG) decreased from SG1 to SG4. Within a litter, one pig was slaughtered and dissected at the beginning of the experiment (55 kg BW) and the three others were fed the same daily supply of protein and amino acids (26 g of lysine/d) but relative daily energy levels were either 113 (without pST: E1/0), 100 (3 mg of pST/d: E2/pST) or 87 (3 mg of pST/d: E3/pST). The 100 energy level corresponded to the ad libitum intake of E2/pST pigs. Two energy and N balances were carried out in respiration chambers during the experimental period. Pigs were slaughtered and dissected at approximately 95 kg BW and composition of gain was estimated using the comparative slaughter technique. In E1/0 pigs, daily BW, lean, and N gain were affected (P less than .01) by group; 566, 471, 374, and 315 g/d of lean tissue gain in SG1, SG2, SG3, and SG4 pigs, respectively. At high ME intake (E2/pST vs E1/0), pST increased daily BW (+14%), lean (+27%), or N (+26%) gain and reduced adipose tissue (-50%) gain, but the pST effect was inversely related to LTG: for N, the improvement was 2.8, 7.1, 7.0, and 11.1 g/d in SG1, SG2, SG3, and SG4 groups, respectively. Energy restriction (E3/pST vs E2/pST) reduced (P less than .001) adipose tissue gain in all groups but did not affect lean tissue or N gains in SG1, SG2, and SG3 pigs. In the pST-treated pigs of the SG4 group, the lean tissue or N gains were reduced (P less than .01) by energy restriction. Energy restriction combined with pST treatment (E3/pST) led to negligible amounts of fat deposited (40 g/d for SG1 + SG2 + SG3 pigs) and a gain:feed ratio higher than 500 g/kg (580 in SG1 pigs). The increased heat production measured in pST-treated pigs was due to its maintenance component: 275 vs 257 kcal of ME.kg BW-.60.d-1 (P less than .01).(ABSTRACT TRUNCATED AT 400 WORDS)     

不同饲养方式对猪生长性能影响的研究

分别选择斯格杂交商品猪60头,同时开展17～40 kg体重阶段的大群饲养（20头/栏）与小群饲养（10头/栏）对比试验,34～60 kg体重阶段的自由采食（10头/栏）与分餐饲喂（10头/栏）对比试验,试验期40 d。结果表明,大群饲养组生长速度比小群饲养组低4.95%（P>0.05）,其日采食量减少9.72%（P>0.05）,饲料转化效率提高5.45%（P>0.05）,头均获毛利减少0.14元;自由采食组生长速度比分餐饲喂组提高13.3%（P<0.05）,其日采食量增加16.87%（P<0.05）,饲料转化效率降低3.14%（P>0.05）,头均获毛利增加11.31元。     

Influence of a conjugated linoleic acid mixture on growth, organ weights, carcass traits and meat quality in growing pigs

Grain soybean meal diets, either with 2% of a conjugated linoleic acid (CLA) preparation or with 2% rapeseed oil (control), were tested in 2 × 40 pigs, Pietrain × (Landrace × Large White), each group with 20 female in the live weight range 23.5–117.0 kg and 20 male-castrated pigs in the live weight range 23.5–110.6 kg. The CLA-content of the preparation amounted to 54.0% cis / trans + trans / cis , 8.7% cis/cis and 32.7% trans / trans isomers. Daily weight gain, feed intake and feed : gain ratio were not influenced by the diets tested. The carcass lean increased significantly from 57.2% of the control group to 58.7% in the CLA group (p   < 0.05). The male-castrated showed a stronger CLA effect than the female pigs – not only was the carcass lean significantly increased by 2%, but backfat thickness was significantly decreased by 2.8 mm, i.e. minus 11% (as compared with barrows of the control). The meat of CLA-fed pigs had a higher conductivity. A CLA effect on further meat quality characteristics (pH 45 min post-mortem, impedance, colour criteria, intramuscular fat, drip loss, frying loss, shear force, sensory attributes) could not be detected. There were some significant correlations between the meat quality attributes.     

猪肌肉糖原磷酸化酶基因的多态性及其与胴体和肉质性状的相关分析

试验旨在寻找不同品种猪的差异表达基因,并对其遗传效应进行初步分析。应用抑制消减杂交技术获得了在梅山猪、长白猪和大白猪中差异表达的肌肉糖原磷酸化酶(glycogen phosphorylase,muscle form,PYGM)基因及其全长cDNA序列,序列分析结果表明,猪PYGM基因编码842个氨基酸,与人、牛、狗、小鼠、大鼠和羊的氨基酸序列具有96%、97%、96%、96%、96%和97%的相似性,而且该基因在各组织中表达量均很高。通过序列比对发现,在3′非翻译区(3′UTR)125 bp处存在1个突变。利用PCR-RFLP方法,在大白猪、梅山猪、长白纯种猪和170头大白×梅山F2代资源家系中检测了该突变位点的多态性并进行性状关联分析,结果表明,该位点的多态性与瘦肉率、骨率、肥肉率、平均背膘厚、眼肌面积、胴体长显著相关,尤其是活体瘦肉率AA基因型(大白猪、长白猪优势基因)比BB基因型(梅山猪优势基因)高3%,肥肉率低5%,与外来猪种瘦肉率显著高于本地猪的性状表现是一致的。因此,猪PYGM基因125 bp位点可能是一个潜在的分子标记辅助常规育种位点。     

沙子岭猪与巴克夏、汉普夏猪的二元杂交试验

研究以沙子岭猪作母本,引进巴克夏、汉普夏作父本进行杂交试验,观察其生产性能。选择体重28 kg左右的纯种沙子岭猪、巴×沙猪和汉×沙猪各10头,分为三组,在前期DE 13.23 MJ、CP 14.37%;后期DE 13.30 MJ、CP 13.55%的营养水平条件下进行为期148 d的育肥饲养试验。结果表明与沙子岭猪比较,巴×沙、汉×沙组合全期日增重分别高40.64%、36.68%（P〈0.01）;料肉比分别低18.68%、18.44%;每增重1 kg饲料成本分别低18.61%、18.42%;瘦肉率分别高7.02%、6.11%（P〈0.01）;眼肌面积分别高55.11%、70.37%（P〈0.01）,三组试验猪猪肉品质均正常。综合分析,巴×沙、汉×沙组合的日增重、饲料转化率、瘦肉率、经济效益等指标均显著优于沙子岭猪,且杂交后代毛色类似地方土猪品种,表明用巴克夏、汉普夏作为沙子岭猪开展二元杂交时的配套父本品种是可行的。     

Effect of a hot environment on performance, carcass characteristics, and blood hormones and metabolites of pigs treated with porcine somatotropin.

A study was conducted to compare the effects of a single 100-mg recombinant porcine somatotropin (rpST) implant on performance, carcass characteristics, and blood hormones and metabolites of 40 finishing pigs exposed to either a thermoneutral (TN; 18 to 21 degrees C) or hot environment (H; 27 to 35 degrees C) for 28 or 35 d. Pigs in H gained at a slower rate (P less than .01) than pigs in TN. Control and rpST-treated pigs gained at similar rates in respective environments. The rpST-treated pigs consumed 13% less feed (P less than .01) than the control pigs in both environments, and pigs in H consumed 19% less feed (P less than .01) than pigs in TN. Feed efficiency for rpST-treated pigs was 15% better (P less than .01) than that for control pigs; environment had no effect on feed efficiency. When slaughtered, pigs treated with rpST had less (P less than .01) leaf fat and less (P less than .01) 10th rib backfat than control pigs. Pigs in H had a lower (P less than .01) final BW and less leaf fat and backfat than pigs in TN. The rpST and H had various effects on blood hormones and metabolites. The results demonstrated that the benefits of this form of rpST treatment achieved under TN were also achieved in H with no interactions between the hormone and environment.     

Tryptophan enhances ghrelin expression and secretion associated with increased food intake and weight gain in weanling pigs

These studies were conducted to determine whether ghrelin, a 28-amino acid peptide produced mainly by the stomach, was involved in tryptophan-mediated appetite stimulation in swine. In experiment 1, 36 crossbred (Long WhitexLarge White) barrows were used in a 2x3 factorial design to determine the effects of food intake (ad libitum versus limit fed) and tryptophan level (0.12%, 0.19% and 0.26%) on growth performance as well as ghrelin expression, plasma insulin, ghrelin and leptin levels. Ad libitum fed pigs gained more weight, but had poorer feed conversion than limit fed pigs. Weight gain, food intake and feed conversion all improved with increased ingestion of dietary tryptophan. Ad libitum feeding increased plasma insulin. Plasma insulin was unaffected by the level of dietary tryptophan. However, plasma leptin was significantly lower in pigs fed 0.19% tryptophan compared to those fed 0.12% tryptophan. Plasma ghrelin levels and ghrelin mRNA level in gastric fundus and duodenun was significantly higher in pigs fed 0.19% and 0.26% tryptophan diet compared with pigs fed 0.12%. In the second experiment, 18 crossbred barrows were divided into three treatments involving oral infusion of saline, tryptophan (40mg/kg BW) or 5-hydroxytryptophan (40mg/kg BW). Plasma ghrelin levels at 20, 40 and 60min after infusion of tryptophan were higher than after saline and 5-hydroxytryptophan infusion, 5-hydroxytryptophan infusion induced lower food intake than saline infusion, and tryptophan infusion increased food intake 2, 8 and 24h after infusion. In conclusion, oral tryptophan ingestion increased ghrelin expression in gastric fundus and plasma ghrelin level.