Effects of beta-glucan extracted from Saccharomyces cerevisiae on growth performance, and immunological and somatotropic responses of pigs challenged with Escherichia coli lipopolysaccharide

Three experiments were conducted to investigate the effects of beta-glucan supplementation on pig performance and immune function. In Exp. 1, 100 weaned pigs (8.65 +/- 0.42 kg of BW and 28 +/- 2 d of age) were used in a 35-d experiment to determine the effects of graded levels of beta-glucan. Pigs were randomly allotted to 1 of 5 treatments containing beta-glucan supplemented at 0, 25, 50, 100, or 200 ppm. Each treatment was replicated using 5 pens containing 4 pigs per pen. The ADG of pigs between d 14 to 28 and d 0 to 28 responded to dietary beta-glucan in a quadratic fashion (P < 0.05), whereas beta-glucan had no effect on ADFI and G:F in any period. In Exp. 2, 80 crossbred pigs (8.23 +/- 0.56 kg of BW and 28 +/- 2 d of age) were used in a 35-d experiment. Pigs were allotted to 1 of 2 dietary treatments (0 or 50 ppm of beta-glucan in the diet) using 10 pens with 4 pigs per pen. Pigs treated with beta-glucan had greater ADG in the 14- to 28-d (P = 0.05) and 0-to 28-d (P = 0.035) periods. The ADFI of pigs receiving beta-glucan was increased (P < 0.05) in the periods from 0 to 14, 0 to 28, and 28 to 35 d. The lymphocyte proliferation index in response to phytohemagglutinin (P = 0.051) and concanavalin A (P = 0.052) tended to decrease on d 14 in pigs supplemented with beta-glucan compared with pigs without supplementation. In Exp. 3, 24 barrows (8.89 +/- 0.20 kg of BW and 28 d of age) were used to investigate the immunological and somatotropic responses of pigs challenged with lipopolysaccharide (LPS). Experimental treatments were arranged in a 2 x 2 factorial, with the main effects of LPS challenge (saline vs. LPS) and dietary addition of beta-glucan (0 vs. 50 ppm). Pigs were raised individually in metabolic cages. Pigs were fed 0 or 50 ppm of beta-glucan for 28 d and then challenged with LPS (25 microg/kg of BW) or saline. After LPS injection, blood was obtained at 0, 1.5, 3, 4.5, 6, and 7.5 h to determine cytokine production and the somatotropic response. Dietary beta-glucan increased plasma interleukin-6 at 1.5, 3, and 4.5 h and tumor necrosis factor-alpha at 3 and 4.5 h and increased plasma interleukin-10 from 3 to 7.5 h after LPS challenge. The beta-glucan treatments had no effect on growth hormone. In conclusion, beta-glucan can selectively influence performance and partially offer benefits on somatotropic axis and immune function in weaned piglets challenged with LPS.     

甘氨酸铁对断奶仔猪血清氧化酶活力及生化指标的影响

试验研究甘氨酸铁对断奶仔猪抗氧化能力及血清生化指标的影响,并初步探讨其作用机理。选用180头体重7.5kg左右的"杜长大"三元杂交仔猪,分为6个处理组,分别饲喂0、30、60、90、120mg/kg甘氨酸铁和120mg/kg硫酸亚铁,试验期5周。结果表明:饲粮中添加甘氨酸铁,均不同程度的提高了血清中SDH、CAT、XOD和AKP的酶活,降低了血尿氮(SUN)、Ca和P含量。由此可知,甘氨酸铁可以影响仔猪机体抗氧化能力和血清生化指标,在一定程度上改善仔猪的生产性能。     

Influence of two supplemental vitamin E levels and weaning age on performance, humoral antibody production and serum cortisol levels of pigs

Three trials using 156 Yorkshire x Hampshire x Duroc crossbred pigs (avg initial wt, 7.9 kg) were conducted to evaluate the effects of two supplemental dietary vitamin E (11 vs 220 IU/kg of diet) and weaning age (21, 28 or 35 d) on performance and immunocompetence of pigs. Supplemental vitamin E (220 IU/kg of diet) increased (P less than .01) serum concentrations of vitamin E for all weaning ages compared with pigs fed 11 IU of vitamin E/kg of diet. However, supplemental vitamin E did not affect performance, serum cortisol concentration or the primary and secondary antibody response to sheep red blood cells. As weaning age increased, weekly ADG and avg daily feed intake increased linearly (P less than .01). Cortisol levels decreased during the 1st wk following weaning and then increased linearly (P less than .01) over time; pigs weaned at 35 d of age had higher (P less than .01) cortisol values initially and over time than pigs weaned at 21 and 28 d. Pigs weaned at 35 d had a higher (P less than .01) primary response to sheep red blood cells than pigs weaned at 21 and 28 d of age, but this effect was not observed for the secondary response. There were no interactive effects (P greater than .10) of dietary vitamin E level and weaning age. In summary, the highest level of supplemental vitamin E increased serum vitamin E concentration but did not affect performance, cortisol levels or one test of the immune response, antibody titers to red blood cells.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of dietary humic substances on pig growth performance, carcass characteristics, and ammonia emission

Five experiments were conducted to test the effects of various dietary humic substances (HS; HS1, 2, 3, and 4, each with different fulvic and humic acid contents) on pig growth, carcass characteristics, and ammonia emission from manure. In Exp. 1, 120 pigs were allotted to 3 dietary treatments without HS (control) or with HS1 at 0.5 and 1.0% (8 pens/treatment and 5 pigs/pen) and fed diets, based on a 5-phase feeding program, from weaning (d 21.3 +/- 0.3 of age) to 60 kg of BW. In Exp. 2 and 3, 384 pigs (192 for each experiment) were allotted to 3 dietary treatments without HS, with HS1, or with HS2 (0.5%) for Exp. 2 and without HS, or with HS3 or HS4 (0.5%) for Exp. 3 (8 pens/treatment and 8 pigs/pen in each experiment). Pigs were fed diets, based on a 6-phase feeding program, from weaning (25.4 +/-0.2 and 23.6 +/-0.3 d of age for Exp. 2 and 3, respectively) to 110 kg of BW. In Exp. 4, 96 pigs were weaned at 22.1 +/-0.2 d of age and allotted to 2 treatments without or with HS1 at 0.5% (6 pens/treatment and 8 pigs/pen), and in Exp. 5 96 pigs were weaned at 20.9 +/-0.3 d of age and allotted to 3 treatments without HS, or with HS3 or HS4 (0.5%; 4 pens/treatment and 8 pigs/pen). Pigs were fed the diets for at least 2 wk before they were moved to an environmental chamber to measure aerial ammonia and hydrogen sulfide for 48 h at 5-min intervals. In Exp. 1, pigs fed diets with HS1 at 0.5% had greater (P < 0.05) ADG during phase 3 and greater (P < 0.05) G:F during phases 3 and 5 than control pigs. In Exp. 2, pigs fed diets with HS1 or HS2 at 0.5% had greater (P < 0.05) ADG and G:F than control pigs during the entire feeding period, whereas in Exp. 3 HS3 or HS4 did not improve pig growth performance. Ammonia emission from manure was reduced by 18 or 16% when pigs were fed diets with HS1 (P = 0.067) or HS4 (P = 0.054), respectively. The results of this study indicate that the effects of dietary HS are variable but may improve growth performance of pigs and reduce ammonia emission from manure. Further research is needed to clarify these effects and the mechanisms by which HS may cause them.     

Effects of stachyose on performance, diarrhoea incidence and intestinal bacteria in weanling pigs.

A three-week trial was conducted to evaluate the effects of the oligosaccharide stachyose on performance, diarrhoea incidence and intestinal bacterial populations in weaned pigs (7.96 +/- 0.2kg). A total of 144 crossbred (Landrace x Large White x Duroc) pigs weaned at 28 days were allotted to one of four treatments with six pens per treatment and six pigs per pen. The experimental diets were based on maize, dried whey and whole-fat milk and were supplemented with 0, 1 or 2% stachyose. A fourth diet contained no milk but instead contained 20% soybean meal to provide 0.78% stachyose and 0.21% raffinose. Inclusion of 1 or 2% stachyose in the diet depressed growth compared with pigs fed the control diet. Pigs fed the soybean meal diet gained weight at a rate similar to pigs fed the diet containing 1% added stachyose. Diarrhoea incidence was highest for pigs fed the soybean meal diet and lowest for pigs fed the control diet, with pigs fed the diets containing stachyose being intermediate. Pigs fed 1% stachyose had more lactobacilli in the ileum as well as more bifidobacteria in the caecum and colon than control pigs. They also had fewer enterobacteria in the colon. In contrast, pigs fed the diet containing 2% stachyose had fewer lactobacilli and bifidobacteria in the jejunum, ileum and caecum than did control pigs. Volatile fatty acids in the ileum, caecum and colon were highest for pigs fed 1% stachyose and lowest for pigs fed 2% stachyose. Volatile fatty acid concentrations were not significantly different between pigs fed the soybean meal diet and those fed the control. The overall results of this experiment indicate that the oligosaccharide stachyose had a negative effect on pig performance and its presence may partially explain the poorer performance observed when soybean meal is used as the sole source of supplemental protein in cereal-based diets fed to weaned pigs.     

Evaluating the antioxidant status of weanling pigs fed dietary vitamins A and E

Two experiments evaluated the relationship of vitamin E (source and level) and vitamin A (level) on the apparent absorption and retention of both vitamins in weaned pigs. Both experiments used a combined total of 460 crossbred pigs ([Yorkshire x Landrace] x Duroc), housed in elevated 1.2- x 1.2-m crates containing five pigs per pen. Experiment 1 was a 2 x 2 x 2 factorial arrangement of treatments in a randomized complete block design conducted in seven replicates. Levels of vitamin A (2,200 or 13,200 IU/kg), vitamin E (15 or 90 IU/kg), and two vitamin E sources (D-alpha-tocopheryl acetate [D-TAc] or DL-alpha-tocopheryl acetate [DL-TAc]) were evaluated over a 35-d period. Vitamin A or E levels and the two vitamin E sources did not affect pig performances to 20 kg BW. Serum retinol and alpha-tocopherol concentrations increased (P < 0.01) as the dietary level of each vitamin increased. Serum alpha-tocopherol declined as dietary vitamin E level increased when vitamin A level increased resulting in an interaction (P < 0.05). Serum alpha-tocopherol concentrations were higher (P < 0.05) at 35-d postweaning when D-TAc was the vitamin E source. Experiment 2 was a 3 x 2 factorial arrangement of treatments conducted in six replicates. Three levels of vitamin A (2,200, 13,200, or 26,400 IU/ kg) and two sources of vitamin E (D-TAc or DL-TAc) each provided at 40 IU/kg diet were evaluated over a 35-d period. Pig performances to 35-d postweaning were not affected by the dietary variables. Serum alpha-tocopherol (P < 0.01) and retinol (P < 0.05) concentrations increased as their respective vitamin level increased. Serum (P < 0.05) and liver (P < 0.01) alpha-tocopherol concentrations both declined as dietary vitamin A levels increased resulting in interaction responses. Serum alpha-tocopherol concentration was higher (P < 0.05) at 35-d postweaning when d-TAc was the vitamin E source. Dietary vitamin E sources had no effect on serum or liver retinol concentrations. These results demonstrated that both supplemental vitamin A and vitamin E increased in the blood as their dietary levels increased. However, as dietary vitamin A level increased, serum and liver alpha-tocopherol concentrations declined, suggesting a reduced absorption and retention of alpha-tocopherol when weaned pigs were fed high dietary vitamin A levels.     

Lack of a nocturnal rise of serum melatonin in prepubertal gilts.

Experiments were conducted to determine if a nocturnal rise in serum melatonin occurs in prepubertal gilts and whether acute exposure of gilts to light during the dark period abruptly reduces serum concentrations of melatonin. In experiment 1, 12 prepubertal crossbred gilts (Duroc x Hampshire x Chester White x Yorkshire) weighing 96.4 + 1.3 kg at 5.1 + .1 mo of age were housed in an LD cycle of 10:14. Following a 3-wk acclimation period, blood samples were drawn at 1-hr intervals from indwelling jugular catheters. Serum concentrations of melatonin were similar (P greater than .05) among blood samples collected during light and dark periods. In experiment 2, serum concentrations of melatonin did not change (P greater than .05) when gilts were abruptly exposed to light during the normal dark period. In experiment 3, serum concentrations of melatonin were similar (P greater than .05) in blood samples collected at 2-hr intervals under 700 lux of light or in total darkness from gilts maintained in either LD 9:15 or LD 24:0. Data from experiment 4 demonstrated that serum melatonin could be detected in nighttime samples if exogenous melatonin was ingested by gilts at night. Together, these experiments clearly indicate that prepubertal gilts do not exhibit a nocturnal rise in serum melatonin when maintained under short daylengths (10L:14D or 9L:15D), and serum melatonin concentrations are unaffected by abrupt changes in light/dark conditions.     

Growth performance,nutrient digestibility,and fecal microflora in weanling pigs fed live yeast

Two experiments were conducted to evaluate the effects of live yeast supplementation on nursery pig performance, nutrient digestibility, and fecal microflora and to determine whether live yeast could replace antibiotics and growth-promoting concentrations of Zn and Cu in nursery pigs. In Exp. 1, 156 pigs were weaned at 17 d of age (BW = 5.9 kg) and allotted to a 2 x 2 factorial randomized complete block design (six or seven pigs per pen with six pens per treatment). Factors consisted of 1) dietary supplementation with oat products (oat flour and steam-rolled oats; 0 or 27.7%) and 2) yeast supplementation at 0 or 1.6 x 10(7) cfu of Saccharomyces cerevisiae SC47/g of feed. In Exp. 2, 96 pigs were weaned at 17 d of age and allotted to a 2 x 2 factorial randomized complete block design (four pigs per pen with six pens per treatment) with factors of 1) diet type (positive control containing growth-promoting concentrations of Zn, Cu, and antibiotics or negative control) and 2) live yeast supplementation (0 or 2.4 x 10(7) cfu of Saccharomyces cerevisiae SC47/g of feed). The inclusion of oat products in Exp. 1 decreased (P < 0.10) overall ADG and final BW. Yeast supplementation did not affect growth performance of pigs in Exp. 1 (P = 0.65); however, ADG in Exp. 2 was 10.6% greater (P < 0.01) and ADFI was increased by 9.4% (P < 0.10) in pigs supplemented with yeast in the positive control diet. Addition of Zn, Cu, and antibiotics to the diet improved gain:feed ratio during the prestarter period (P < 0.02) and overall (P = 0.10). In Exp. 1, inclusion of oat products increased (P < 0.01) total bacteria in feces when measured on d 10. Fecal lactobacilli measured on d 28 were reduced (P < 0.05) in pigs fed diets with oat products and yeast (interaction, P < 0.05). In Exp. 2, yeast supplementation decreased (P < 0.05) total bacteria and lactobacilli. Dietary yeast resulted in a greater (P < 0.05) yeast count in feces of pigs during the starter phase of Exp. 1. Yeast decreased (P < 0.10) the digestibility of DM, fat, and GE in the prestarter phase and DM, fat, P, and GE in the starter phase, whereas oat products increased the digestibility of DM, CP, fat, and GE (P < 0.05) in the prestarter phase. Results indicate that live yeast supplementation had a positive effect on nursery pig performance when diets contained growth-promoting antimicrobials. Nonetheless, the response was variable, and the conditions under which a response might be expected need to be further defined.     

复方中草药“强普素”对断奶仔猪生长性能和免疫功能的影响

目的：本试验旨在研究复方中草药“强普素”对断奶仔猪生长性能和免疫功能的影响.方法：选用144头（28±1）日龄平均质量为（8.30±0.14） kg的杜×长×大断奶仔猪,按照单因素完全随机化原则分为4个处理组,每组设3个重复,每个重复12头.试验设1个空白对照组和3个复方中草药“强普素”添加组,添加量分别为0.05％、0.1％、0.2％.结果：与空白对照组相比,日粮中添加0.1％和0.2％复方中草药“强普素”组的平均日增重显著提高（P＜0.05）,料重比显著降低（P＜0.05）;IgG及补体C3、C4的含量均显著高于空白对照组（P＜0.05）.而日粮中添加0.05％复方中草药“强普素”组的平均日增重、料重比、IgG、补体C3及C4的含量与对照组相比差异不显著（P＞0.05）.结论：复方中草药“强普素”具有提高断奶仔猪生长性能和免疫功能的作用,以0.1％添加量效果最佳.     

甜菜碱对生长肥育猪体脂重分配的作用及机理研究

通过48头20～65　kg生长猪和60头60～95　kg肥育猪（Duroc×Landrace×Yorkshire）饲养、屠宰试验和有关生化指标分析，探讨了甜菜碱对生长肥育猪皮下脂肪沉积、胴体脂肪率和肌内脂肪含量的影响及其作用机理。48头生长猪和60头肥育猪分别分成对照和试验2个处理组，每个处理含3个重复，生长猪和肥育猪的试验组分别饲喂含1000　mg／kg和1500　mg／kg甜菜碱的饲粮。结果表明添加甜菜碱，提高了生长猪的日增重13.20％（P＜0.05），降低了料重比7.93％（P＜0.05）；分别降低生长猪和肥育猪的背膘厚14.82％（P＜0.05）和14.93％（P＜0.05）、脂肪率5.76％（P＞0.05）和11.51％（P＜0.05）；分别提高背最长肌肌内粗脂肪含量36.00％（P＜0.05）和17.66％（P＜0.05）。血清生化指标分析表明甜菜碱分别提高生长猪和肥育猪脂肪酶活性10.49％（P＜0.05）和7.50％（P＝0.06），分别提高了血清游离脂肪酸含量20.16％（P＜0.05）和13.43％（P＜0.05），显示甜菜碱加强了猪体脂动员。进一步研究表明，饲喂甜菜碱的生长猪和肥育猪肝脏游离肉碱含量分别提高了20.68％（P＜0.05）和23.53％（P＜0.05），肥育猪背最长肌中酸不溶肉碱含量以及酸不溶肉碱和游离肉碱比例分别提高了48.59％（P＜0.01）和38.24％（P＜0.01），结果揭示甜菜碱似通过提供肉碱合成所必需的甲基以提高生长肥育猪肝脏游离肉碱的含量，促进长链脂肪酸进入肌肉线粒体进行β-氧化，在减少体脂（主要是皮下脂肪）同时，适度增加肌肉脂肪含量，从而发挥着重新分配体脂的作用。     

Effect of lactoferrin on the growth performance, intestinal morphology, and expression of PR-39 and protegrin-1 genes in weaned piglets

A total of 90 weaned female pigs (Duroc x Landrace x Yorkshire) were used in a 15-d growth experiment to investigate the effect of lactoferrin on growth performance, intestinal morphology, and expression of PR-39 and protegrin-1 genes. The pigs were allocated on the basis of BW and litter to 3 dietary treatments in a randomized complete block design. There were 3 replicate pens per treatment, and the pigs were grouped with 10 pigs per pen. The dietary treatments were (1) basal diet; (2) basal diet + 20 mg of flavomycin/kg + 110 mg of aureomycin/kg; (3) basal diet + 1.0 g of lactoferrin/kg. Six pigs, randomly selected from each treatment (2 piglets/pen) were slaughtered for intestinal morphology and expression of PR-39 and protegrin-1 genes at the end of the experiment. Supplementation with lactoferrin improved growth performance; it increased ADG by 41.80% (P < 0.01) and efficiency of gain (G:F) by 17.20% (P < 0.05). Intestinal villus height was increased by 15.30% (P < 0.05), and crypt depth was decreased by 9.60% (P < 0.05). Supplemental lactoferrin increased the relative abundance of mRNA for PR-39 and protegrin-1 by 143% (P < 0.01) and 217% (P < 0.01), respectively. The use of lactoferrin as an additive to improve nonspecific immunity and strengthen host defenses would be good a method of defending weaned pigs from infections and weanling stress.     

Humoral and cell-mediated immune response and performance of weaned pigs fed four supplemental vitamin E levels and housed at two nursery temperatures

Three trials using 80 Yorkshire x Hampshire x Duroc crossbred pigs (avg initial wt, 6.9 kg) were conducted to determine the effects of four dietary vitamin E levels (11, 110, 220 and 550 IU/kg of feed) on the humoral and cell-mediated immune response and performance of 4-wk-old weanling pigs housed at two nursery temperatures (19 or 30 degrees C). Interactive effects of temperature and vitamin E were not observed for any measurements. Serum and liver vitamin E levels increased linearly with increasing level of dietary vitamin E, but performance, cortisol, antibody levels and mitogen-induced stimulation indices were not affected by supplemental levels of vitamin E. Average daily gain and feed intake were higher (P less than .01) for pigs housed at 19 degrees C than for pigs housed at 30 degrees C, but feed:gain ratios, mitogen stimulation index of white blood cells, plasma cortisol levels and antibody titers were not altered. Although supplemental vitamin E above the NRC estimated requirement increased serum and liver vitamin E concentrations, no differences were observed in humoral and cell-mediated immune response, cortisol levels or performance for weanling pigs housed at either 19 or 30 degrees C temperatures.     

Effects of timing and duration of dietary vitamin A reduction on carcass quality of finishing beef cattle

Two feedlot studies were conducted to investigate the timing and duration of supplemental vitamin A withdrawal from feedlot cattle (Bos taurus) diets to reduce intramuscular adipose tissue vitamin A concentration and improve carcass quality. In Exp. 1, Angus crossbred steers (n = 84, BW = 211 ± 4 kg) were allotted to 4 treatments: no supplemental vitamin A for 227 d, no supplemental vitamin A for 112 d followed by 115 d of supplemental vitamin A, supplemental vitamin A for 112 d followed by no supplemental vitamin A for 115 d, or supplemental vitamin A for 227 d. In Exp. 2, Angus crossbred steers (n = 80, BW = 210 ± 5 kg) were allotted to 4 treatments: early weaning with or without supplemental vitamin A, and traditional weaning with or without supplemental vitamin A. In both experiments, serum vitamin A concentrations were greatest (P < 0.05) 56 d after cattle were weaned and placed in the feedlot, regardless of feedlot dietary vitamin A concentration. Hepatic vitamin A stores were dramatically decreased (P < 0.05) in the first 56 d and remained depressed as long as steers were not supplemented with vitamin A. At the end of the finishing period, vitamin A concentrations were less in intramuscular than subcutaneous adipose tissue. Growth was not affected by finishing cattle without supplemental dietary vitamin A (P > 0.10). Dietary vitamin A supplementation did not affect USDA yield grades. However, in Exp. 2, cattle without supplemental vitamin A had greater (P < 0.001) ether extractable lipid in the LM. Ether extractable lipid in the LM or marbling scores were enhanced when intramuscular adipose tissue vitamin A concentration was reduced in response to feeding diets without supplemental vitamin A.     

啤酒酵母葡聚糖对断奶仔猪生产性能及淋巴细胞转化率的影响

为了探讨啤酒酵母葡聚糖在断奶仔猪日粮中的适宜添加剂量及其对断奶仔猪细胞免疫功能的影响,本研究进行了2个试验。试验1选用100头(28±2)d断奶的二元杂交断奶仔猪,按单因子试验设计随机分为5个处理,分别饲喂含葡聚糖0、25、50、100mg/kg和200mg/kg的日粮。结果表明:随葡聚糖添加剂量的增加,平均日增重在14￣28 d及0￣28 d呈二次曲线变化(P<0.05)。试验2选用80头(28±2)d断奶的二元杂交断奶仔猪,随机分为2个处理,分别饲喂含葡聚糖0mg/kg和50mg/kg的日粮。在试验的第14天和第28天,每重复取1头仔猪前腔静脉采血,测定外周血淋巴细胞转化率。结果显示,在断奶仔猪日粮中添加50mg/kg葡聚糖提高了仔猪在14￣28d及0￣28d的日增重(P<0.05)。而且,也提高了仔猪在0￣14 d、0￣28 d及28￣35 d的平均日采食量(P<0.05)。但是对淋巴细胞转化率没有影响。结果表明:在断奶仔猪日粮中添加50mg/kg啤酒酵母葡聚糖,可以提高断奶仔猪的生产性能,而且没有性别差异。     

五味子、柠檬酸对断奶仔猪血清生化指标和免疫功能的影响

选择28日龄断奶二元杂交(长白×大约克)仔猪48头,断奶体重(7.4±0.6)kg,平均分为4个组,每组3个重复,每重复4头(公、母各半),研究日粮中添加五味子(SC)、柠檬酸(CA)对断奶仔猪血清生化指标以及免疫功能的影响。试验组分别添加1%CA、0.5%SC、1%CA+0.5%SC,对照组为玉米-豆粕型基础日粮。结果表明:与对照组相比,CA+SC组血清尿素氮(BUN)水平和谷丙转氨酶(ALT)活性显著降低(P<0.05),SC组血清BUN水平和碱性磷酸酶(ALP)活性显著降低(P<0.05),ALT活性极显著降低(P<0.01)。CA+SC组T3水平显著提高(P<0.05)。与对照组相比,SC组血清中猪瘟抗体效价、IgG和IgA水平显著提高(P<0.05)。SC组、CA+SC组血清白细胞介素-2(IL-2)水平显著高于对照组(P<0.05)。     

Effect of vitamin E on improving fresh pork quality in Berkshire- and Hampshire-sired pigs

This study was designed to evaluate the effects of vitamin E supplementation on pork quality of two genotypes with distinct differences in pork quality traits. Pigs (n = 240; BW = 87 +/- 0.35 kg) were allotted by weight to one of 20 treatments (4 pens/treatment, 3 pigs/pen) in a 2 x 2 x 5 factorial randomized complete block design. Factors included 1) genotype (Berkshire or Hampshire sired), 2) sex (gilts or barrows), and 3) vitamin E level (12.1, 54.7, 98.8, 174.0, and 350.6 IU of vitamin E/kg diet). Hampshire-sired pigs had greater average daily gain (1.05 vs 0.98 kg) and gain:feed (0.30 vs 0.27) and less average daily feed intake (ADFI) (3.46 vs 3.62 kg) than Berkshire-sired pigs (P < 0.001) for the 6-wk study. Hampshire-sired barrows consumed more feed (3.54 vs 3.38 kg/d) and were less efficient (0.29 vs 0.31) than Hampshire-sired gilts (P < 0.05), but this sex difference was not observed in Berkshire-sired pigs (interaction, P < 0.05). Berkshire-sired pigs had greater backfat (34.1 vs 21.1 mm; P < 0.001), reduced longissimus muscle area (37.6 vs 46.3 cm2; P < 0.001), reduced lean percentage (53.0 vs 55.8; P < 0.001), and a greater head-on yield (79.8 vs 79.2; P < 0.05). Vitamin E increased (P < 0.05) ADFI linearly (P < 0.05), but had no effects on carcass composition. Loin chops from Hampshire-sired pigs had reduced ultimate pH (5.64 vs 5.91), greater drip loss (92.2 vs 66.3 mg), and increased Minolta L* (52.6 vs 48.6), a* (8.9 vs 7.5), and b* (6.9 vs 5.2) values compared to Berkshire-sired pigs (P < 0.001). Vitamin E had no effect on pH, temperature, drip loss, and L* or a* values, but tended (P < 0.07) to increase b* values linearly (P < 0.06). Oxidation as indicated by thiobarbituric acid reactive substances (TBARS) was greatest in Hampshire-sired gilts at the lowest level of vitamin E, and decreased linearly (P < 0.001) with additional vitamin E. However, TBARS responded in a cubic fashion (P < 0.05) to vitamin E in Hampshire-sired barrows and were not affected in Berkshire-sired gilts or barrows (three-way interaction, P < 0.02). Hampshire-sired pigs had greater TBARS than Berkshire-sired pigs (0.053 vs 0.047 mg malondialdehyde equivalents/kg). Vitamin E supplementation increased serum concentrations of vitamin E on d 21 (1.06 to 4.79 microg/mL) and d 42 (1.02 to 2.82 microg/mL) and increased tissue concentrations of vitamin E (1.99 to 4.83 microg/g) linearly (P < 0.001). Vitamin E supplementation was not effective in improving fresh meat quality in genotypes with poor or superior meat quality traits.     

Responses of weanling pigs to dietary supplementation with vitamin C or carbadox

A 2 X 2 factorial arrangement with two levels (0, 660 ppm) of vitamin C and two levels (0, 55 ppm) of carbadox supplementation was used in two experiments with 112 crossbred pigs weaned between 4 and 5 wk of age. An 18% protein corn-soybean meal-oats-dried whey starter diet was used as the basal diet. Each diet was fed ad libitum for a 4-wk period to three replicates of four pigs in Exp. 1 and to four replicates of four pigs in Exp. 2. Vitamin C supplementation produced a significantly higher plasma vitamin C concentration in weanling pigs, but, contrary to results of our previous study, failed to improve average daily gain of the pigs. Daily gain was, however, improved significantly by carbadox supplementation. Carbadox also produced a significantly higher plasma vitamin C concentration in pigs after a 7-d lag period. Plasma Fe concentration of pigs was not affected by supplemental vitamin C, but was significantly higher in those fed carbadox-supplemented diets. Plasma ceruloplasmin concentration increased significantly in all treatment groups from the initial sampling period (d 0) to subsequent periods. No interactions between supplemental vitamin C and carbadox were observed in daily gain, feed efficiency and the measured plasma constituents.     

Effects of ractopamine supplementation on growth performance and carcass characteristics of feedlot steers differing in biological type

Effects of ractopamine hydrochloride (RAC) supplementation on growth performance and carcass characteristics of feedlot steers differing in biological type were investigated using British, Continental crossbred, and Brahman crossbred calf-fed steers (n = 420). Steers of each type were weighed at reimplantation [British, mean BW = 375 kg (SD = 38 kg); Continental crossbred, mean BW = 379 kg (SD = 42 kg); Brahman crossbred, mean BW = 340 (SD = 32 kg)] and sorted into 7 BW blocks, each block consisting of 2 pens (10 steers per pen) per type. Pens within a block x type subclass were randomly assigned to RAC treatments (0 or 200 mg x steer(-1) x d(-1) fed during the final 28 d of the finishing period). The type x RAC interaction did not affect (P > 0.05) any of the traits evaluated in this study. Feeding RAC improved (P = 0.001) ADG (1.50 vs. 1.73 +/- 0.09 kg) and G:F (0.145 vs. 0.170 +/- 0.005), but did not affect (P = 0.48) DMI of steers. Dressing percentage, adjusted fat thickness, KPH percentage, and yield grade were not affected by RAC supplementation. Carcasses of steers fed RAC had heavier (P = 0.01) HCW (359 vs. 365 +/- 4.9 kg), larger (P = 0.046) LM areas (81.7 vs. 84.0 +/- 1.1 cm(2)), and tended (P = 0.07) to have lower mean marbling scores (487 vs. 477 +/- 5.2; Slight = 400, Small = 500) than did carcasses of control steers. Among the 3 biological types, Brahman crossbred steers had the lowest DMI and produced the lightest-weight carcasses that had the lowest mean marbling score (P < 0.05). Compared with Continental crossbred and Brahman crossbred steers, British steers produced carcasses with the greatest (P = 0.001) mean marbling scores. Continental crossbred steers had the heaviest BW and greatest dressing percentages and produced the heaviest carcasses with the largest LM areas (P < 0.05) compared with British and Brahman crossbred steers. In the present study, 28 d of supplementation with RAC at a dosage rate of 200 mg x steer(-1) x d(-1) elicited consistent responses in growth performance and carcass traits among 3 diverse biological cattle types.     

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.     

圆环病毒攻击下生物素添加水平对仔猪细胞免疫及生产性能的影响

将28d断奶、圆环病毒(PVC2)抗体阴性的(杜×长×大)三元杂交仔猪54头,平均分为6组,每组9头,单笼饲养。试验第1天全部猪口鼻接种圆环病毒,在玉米-豆粕型基础日粮中分别添加生物素0、0.10、0.20、0.30、0.40mg/kg和0.50mg/kg,以确定PCV2攻击下,仔猪饲粮生物素添加水平对细胞免疫及生产性能的影响。结果表明:饲粮中添加生物素0.30mg/kg,仔猪外周血E总花环形成率和T淋巴细胞转化率较高,并可促进外周淋巴器官维持正常形态、提高胸腺生长指数;添加0.50mg/kg提高生产性能的效果最佳。由本试验可得出,添加生物素可促进仔猪淋巴器官生长和细胞免疫反应并能提高生产性能,以添加0.30mg/kg的效果较好。