营养水平对鲁农2号配套系生长肥育猪生长性能以及养分消化率的影响

为探讨鲁农2号配套系生长肥育猪适宜的能量和粗蛋白质需要量,试验采用单因子随机区组设计,在保持消化能/粗蛋白质比不变的基础上,设为高能量粗蛋白质、中能量粗蛋白质和低能量粗蛋白质3个处理组。选取健康、初始体重（49.58±1.49）kg的鲁农2号配套系生长肥育猪108头（公母各半）随机分3个处理,每个处理4个重复,每个重复（圈）9头猪。试验分为50～80 kg和80～100 kg两个阶段。结果表明,试验全期饲粮营养水平的降低对猪日采食量、日增重和料重比影响不显著,但50～80 kg低营养水平组日增重和粗蛋白质日摄入量显著低于高、中营养水平组。养分表观消化率,50～80 kg以低营养水平组最高,与中营养水平组相比,其干物质、有机物、粗蛋白质和能量的表观消化率分别提高6.97%、8.53%、10.48%和6.45%,差异显著。饲粮营养水平对钙和磷的表观消化率均无显著影响（P〉0.05）。80～100 kg不同营养水平组养分表观消化率差异显著,其中,高营养水平组养分表观消化率最高,其干物质表观消化率分别比中、低营养组提高5.49%和7.17%（P〈0.05）;有机物的表观消化率分别提高4.48%和6.07%（P〈0.05）;钙的表观消化率分别提高32.76%和27.93%（P〈0.05）;磷的表观消化率分别提高38.77%（P〈0.05）和17.44%;粗蛋白质的表观消化率比中营养水平组提高8.56%（P〈0.05）。综合考虑,在50～80 kg阶段,鲁农2号配套系生长猪适宜的消化能为12.98 MJ/kg、粗蛋白质为14.56%;80～100 kg阶段,鲁农2号配套系肥育猪适宜的消化能为12.98 MJ/kg、粗蛋白质为12.40%。     

牛至提取物对生长育肥猪生长性能、胴体性状及肉品质的影响

本试验旨在研究牛至提取物对生长育肥猪生长性能、胴体性状及肉品质的影响。将126头体重为(41.64±1.63)kg的杜×长×大生长育肥猪随机分为3组,对照组饲喂基础日粮,试验组分别在基础日粮中添加300、500 mg/kg牛至提取物。每组设3个重复,每个重复14头。预试期5 d,正试期92 d。试验结束时,测定生长育肥猪生长性能、胴体性状和肉品质。结果表明:与对照组相比,300、500 mg/kg牛至提取物组平均日增重、平均日采食量显著提高,耗料增重比显著降低,肌肉中肌苷酸含量显著提高;500 mg/kg牛至提取物组肉色、屠宰后pH45min显著高于对照组和300 mg/kg牛至提取物组,滴水损失则显著降低;各组屠宰率、瘦肉率、平均背膘厚、眼肌面积以及肌肉的水分、粗脂肪、粗蛋白质和粗灰分含量差异不显著。以上结果表明,日粮添加500 mg/kg牛至提取物可提高生长育肥猪生长性能,改善肉品质和风味。     

体重对商品猪肥育性能及胴体肉品质的影响研究

选择体重35kg左右的杂交猪34头,采用饲养试验和屠宰试验,研究了育肥结束体重和屠宰体重对试验猪的肥育性能及胴体肉品质的影响。结果显示:育肥结束体重在85~110 kg阶段对试验猪的生长肥育性能没有显著的影响;屠宰体重除对屠宰率形成显著差异外,对试验猪的其它胴体性能及肉品质影响不明显;采用综合选择指数对试验猪肥育性能及胴体肉品质进行综合评定,结果显示,体重在95~100kg阶段结束育肥并屠宰的试验猪生长性能及胴体肉品质的综合选择指数最大。因此,在该试验日粮水平下杜莱商品猪的适宜育肥结束及屠宰体重为95~100kg。     

日粮组成和能量水平对乌金猪肉品质的影响

本文旨在研究不同日粮组成和能量水平对乌金猪肉品质的影响,确定最优肉品质所需的日粮适宜能量水平.选取体重(15.18±0.85)kg的乌金猪90头,公、母各占1/2,随机分为5组,每组18头,下设3个重复,每个重复6头.试验采用单因子随机分组设计,以中国肉脂型生长肥育猪饲养标准能量需要设计中能量水平(组Ⅲ,消化能12.98 MJ/kg),以NRC(1998)生长肥育猪饲养标准能量需要设计最高能量水平(组Ⅰ,消化能14.22 MJ/kg),此两个能量水平间设计中高能量水平(组Ⅱ,消化能13.60 MJ/kg),在中能量水平下依次分别设计中低能量水平(组Ⅳ,消化能12.36 MJ/kg)和最低能量水平(组Ⅴ,消化能11.74 MJ/kg),每个能量水平间的梯度为0.62 MJ/kg.各组在不同生长阶段日粮蛋白质、微量元素、氨基酸等水平基本固定.试验期至100 kg体重,分别在30、60和100 kg体重时屠宰,测定肉品质指标及肌肉营养成分,采用模糊综合评定系统分析并确定最优肉品质日粮适宜能量水平.结果表明,不同日粮组成和能量水平对乌金猪不同生长阶段肌肉pH、系水力、剪切力、烹煮损失和滴水损失有明显影响,组Ⅰ、Ⅲ、Ⅴ及其日粮的组间差异显著(P<0.05),大理石纹在60和100 kg体重时差异显著(P<0.05).随着日粮能量水平的降低,肌肉中粗蛋白质含量提高,在100 kg体重时达显著水平(P<0.05);粗脂肪、肌内脂肪和肌苷酸含量降低,不同生长阶段组Ⅰ、Ⅲ、Ⅴ及其日粮的组间差异显著或极显著(P<0.05或P<0.01).以大理石纹、剪切力、滴水损失为评定肉品质的代表指标,通过综合评定确定30、60和100 kg体重时最优肉品质适宜的日粮能量水平分别为13.10、13.08和13.11 MJ/kg.研究结果可为乌金猪的合理饲养和改善肉品质提供科学依据.     

中草药制剂在生长育肥猪中的应用研究

选择20kg左右,胎次、日龄相近的DLY生长育肥猪96头,按照体重相似的原则随机分为添加0.1%中草药制剂组和对照组,每组6个重复,每个重复8头猪,研究对DLY生长育肥猪生产性能、胴体性状及肉品品质的影响。通过饲养试验、消化试验及屠宰试验,并对背最长肌进行采样,测定分析其肉品品质。结果表明,生长育肥猪日粮中添加中草药制剂具有提高其生产性能、改善其胴体性状及肉品品质的趋势。     

体重对商品猪肥育性能及胴体肉品质的影响研究

选择体重35kg左右的杂交猪34头,采用饲养试验和屠宰试验,研究了育肥结束体重和屠宰体重对试验猪的肥育性能及胴体肉品质的影响.结果显示:育肥结束体重在85～110 kg阶段对试验猪的生长肥育性能没有显著的影响;屠宰体重除对屠宰率形成显著差异外,对试验猪的其它胴体性能及肉品质影响不明显;采用综合选择指数对试验猪肥育性能及胴体肉品质进行综合评定,结果显示,体重在95～100kg阶段结束育肥并屠宰的试验猪生长性能及胴体肉品质的综合选择指数最大.因此,在该试验日粮水平下社莱商品猪的适宜育肥结束及屠宰体重为95～100kga.     

饲粮能量水平对渝荣Ⅰ号猪肥育后期生产性能和胴体肉质的影响

试验选用体重80 kg左右的渝荣Ⅰ号肥育猪60头,随机分为5个处理组,分别饲喂消化能浓度为12.99、13.49、14.09、14.57和15.07 MJ/kg的饲粮,每组3个重复,每个重复4头猪(公母各半),研究不同能量水平对猪肥育后期生产性能和胴体肉质的影响.结果表明:渝荣Ⅰ号猪肥育后期(80～120 kg)消化能浓度为14.09 MJ/kg时生产性能最佳.随着饲粮消化能浓度的提高采食量下降、料肉比降低,日增重各组间差异不显著(P>0.05).平均背膘厚和屠宰率随着饲粮中消化能水平的提高有上升趋势,但在最高能量组(15.07 MJ/kg)出现了下降,瘦肉率的变化与背膘厚和屠宰率相反;饲粮消化能浓度对各肉质性状均无显著影响(P>0.05).     

木棉籽油对育肥猪生长性能、胴体性状、肉品质及经济优势的影响

文章旨在评估木棉籽油替代大豆油对育肥猪生长性能、胴体性状和肉品质的影响.试验将500头20?w平均体重为(84.40±0.18)kg的育肥猪随机分为2组,每组5个重复,每个重复50头.对照组饲喂含有1.5％大豆油的基础日粮,处理组饲喂含有0.8％木棉籽油的基础日粮,试验分为0～3?w和4～6?w共42?d.结果:对照组...     

饲粮粗蛋白质水平对“硒都黑”猪生长性能和血清生化指标的影响

为研究不同粗蛋白质水平饲粮对"硒都黑"猪生长性能和血清生化指标的影响,试验选取90头平均体重为31 kg左右的健康"硒都黑"猪,随机分为3组,每组3个重复,每个重复10头,公母比例一致,进行30~60 kg阶段试验,3个处理分别饲喂粗蛋白质水平为16.9%、15.4%和13.9%的能量相近的饲粮,试验期40 d。选择81头平均体重为55 kg左右的健康"硒都黑"猪,随机分为3组,每组3个重复,每个重复9头,公母比例一致,进行60~90 kg阶段试验,3个处理分别饲喂粗蛋白质水平为15.0%、13.5%和12.1%的能量相近的饲粮,试验期45 d。结果表明,"硒都黑"猪最佳生长性能所需的饲粮适宜粗蛋白质水平为30~60 kg阶段15.4%、60~90 kg阶段13.5%;该粗蛋白质水平组"硒都黑"猪血清中总蛋白和白蛋白含量高于其他两组,尿素氮低于其他两组,但均差异不显著(P0.05);每千克增重饲料成本低于其他两组,但差异不显著(P0.05)。     

不同膨化亚麻籽日粮饲喂程序对生长育肥猪生长性能、脂肪酸沉积和免疫功能的影响

试验旨在研究不同膨化亚麻籽日粮饲喂程序对生长育肥猪生长性能、屠宰性能、脂肪酸沉积及免疫功能的影响.选取初始体重为(36.76±0.49)kg的杜×巴×嘉生长育肥猪120头,随机分为4组,每组3个重复,每个重复10头,试验期90 d.对照组全程饲喂基础日粮,T30、T60和T90组先饲喂基础日粮并分别于屠宰前30、60、...     

四川黑猪适宜能量蛋白水平的研究

选择96头70日龄四川黑猪随机分成3个处理,每个处理4个重复,每个重复8头猪,饲养于同一个圈,在生长猪（25～60kg）和育肥猪（60～100kg）阶段分别随机饲喂3种日粮（3个能量水平、2个蛋白水平）,以便探明生长肥育阶段四川黑猪的适宜能量和蛋白水平。试验结果表明：四川黑猪在生长猪和育肥猪阶段,生产性能表现较好的日粮营养水平分别为消化能3.2Mcal/kg、粗蛋白15%和消化能3.3Mcal/kg、粗蛋白14%。     

Effect of dietary L-carnitine on growth performance and body composition in nursery and growing-finishing pigs.

Two experiments were conducted to determine the effect of dietary L-carnitine on growth performance and carcass composition of nursery and growing-finishing pigs. In Exp. 1,216 weanling pigs (initially 4.9 kg and 19 to 23 d of age) were used in a 35-d growth trial. Pigs were blocked by weight in a randomized complete block design (six pigs per pen and six pens per treatment). Four barrows and four gilts were used to determine initial carcass composition. L-Carnitine replaced ground corn in the control diets to provide 250, 500, 750, 1,000, or 1,250 ppm. On d 35, three barrows and three gilts per treatment (one pig/block) were killed to provide carcass compositions. L-Carnitine had no effect (P > 0.10) on growth, percentages of carcass CP and lipid, or daily protein accretion. However, daily lipid accretion tended to decrease and then return to values similar to those for control pigs (quadratic P < 0.10) with increasing dietary L-carnitine. In Exp. 2, 96 crossbred pigs (initially 34.0 kg BW) were used to investigate the effect of increasing dietary L-carnitine in growing-finishing pigs. Pigs (48 barrows and 48 gilts) were blocked by weight and sex in a randomized complete block design (two pigs/pen and eight pens/treatment). Dietary L-carnitine replaced cornstarch in the control diet to provide 25, 50, 75, 100, and 125 ppm in grower (34 to 56.7 kg; 1.0% lysine) and finisher (56.7 to 103 kg; 0.80% lysine) diets. At 103 kg, one pig/pen was slaughtered, and standard carcass measurements were obtained. Dietary L-carnitine did not influence growth performance (P > 0.10). However, increasing dietary carnitine decreased average and tenth-rib back-fat (quadratic, P < 0.10 and 0.05), and increased percentage lean and daily CP accretion rate (quadratic, P < 0.05). Break point analysis projected the optimal dosage to be between 49 and 64 ppm of L-carnitine for these carcass traits. It is concluded that dietary carnitine fed during the nursery or growing-finishing phase had no effect on growth performance; however, feeding 49 to 64 ppm of L-carnitine during the growing-finishing phase increased CP accretion and decreased tenth-rib backfat.     

诱食剂对育肥猪生产性能的影响

本试验旨在研究含有诱食剂的预混料对育肥猪生产性能的影响。试验选择60 kg左右的杜×大×长育肥猪108头,随机平均分到试验组和对照组中。试验组使用含有诱食剂的预混料,对照组使用不含有诱食剂的预混料。试验结果显示,添加含有诱食剂的预混料能够显著提高育肥猪的日增重15.4%(P<0.05),采食量极显著提高了15.8%(P<0.01),料肉比提高了0.1%,但差异不显著(P＞0.05),收入提高了15.3%。试验结果表明,使用含有诱食剂的预混料饲喂育肥猪,可以取得较为满意的经济效益。     

高温高湿环境下饲粮能量水平对生长肥育猪生长性能、血清生化指标和肉品质的影响

本试验旨在研究不同饲粮消化能水平在高温高湿饲养环境下对生长肥育猪生长性能、血清生化指标和肉品质的影响,以确定生长肥育猪适宜的消化能水平。选取平均初始体重为(40.0±2.0)kg的健康“杜×长×大”生长猪50头,随机分为5个组,每个组10个重复(7头公猪,3头母猪),每个重复1头猪。5个组试验猪分别饲喂消化能水平为13.68、13.88、14.09、14.30和14.51 MJ/kg的饲粮,试验期为90 d。结果表明:1)在高温高湿环境下,随着饲粮消化能水平的提高,试验猪生长期、育肥期及试验全期的平均日采食量呈下降趋势,而平均日增重(ADG)呈先升高后降低、料重比呈先降低后升高的趋势。猪生长期和全期的ADG与饲粮消化能水平的曲线方程分别为Y1=-878.02X^2+24708.94X-173289.53(R^2=0.69,P<0.01)和Y2=-436.56X^2+12276.96X-85600.33(R^2=0.54,P<0.05),当ADG达到最大时,对应的饲粮消化能水平分别为14.07和14.06 MJ/kg。2)饲粮消化能水平对生长肥育猪血清总蛋白、高密度脂蛋白胆固醇和免疫球蛋白G含量存在显著影响(P<0.05),并且以14.09 MJ/kg消化能组最高(P<0.05)。3)饲粮消化能水平对生长肥育猪血清脂蛋白脂肪酶、脂肪酶(LPS)活性分别有极显著(P<0.01)和显著性(P<0.05)影响,而对血清苹果酸脱氢酶活性以及脂联素和生长激素含量没有显著影响(P>0.05);猪血清LPS活性与饲粮消化能水平的曲线方程为Y3=133.00X^2-3761.26X+26664.78(R^2=0.83,P<0.05),当血清LPS活性最低时,对应饲粮消化能水平为14.14 MJ/kg。4)随着饲粮消化能水平的提高,生长育肥猪的皮脂率显著提高(P<0.05),肌肉滴水损失和剪切力显著降低(P<0.05),并以14.09 MJ/kg消化能组的肉品质最优,其滴水损失和剪切力显著低于13.68 MJ/kg消化能组(P<0.05);猪肉滴水损失和剪切力与饲粮消化能水平的曲线方程分别为Y4=0.70X^2-19.92X+143.25(R^2=0.96,P<0.05)和Y5=2.88X^2-82.20X+590.36(R^2=0.99,P<0.05),当肌肉滴水损失、剪切力达到最低时,对应的饲粮消化能水平分别为14.23和14.27 MJ/kg。     

Influence of increased feeding frequency on behavior and integument lesions in growing-finishing restricted-fed pigs

This study evaluated how feeding frequency affects behavior and the occurrence of skin lesions in growing-finishing pigs. One hundred eighty pigs (27 to 112 kg of BW) were reared in one environmentally controlled room (20 pens; 9 pigs/pen). Pigs in 10 pens were fed 3 times daily (reference group), whereas the others were fed 9 times daily (experimental group). Both groups received the same total amount of liquid feed. Rations were adjusted to the mean pen weights. Behavioral observations (scan sampling, as well as continuous focal pig observations) were made in wk 4, 10, and 14 of the growing-finishing period. After each observation, skin lesions were assessed individually for each pig. Pigs fed 9 times daily tended to lie laterally for less time (P = 0.083) and tended to be active (P = 0.054) during the day, especially in growing-finishing wk 4 (P = 0.007). With continuously observed focal pigs, no differences in time allocations for feeding were found between groups. During feeding in growing-finishing wk 4, focal pigs belonging to the experimental group displayed more aggressive actions (P = 0.019), tended to perform aggressive actions for a longer time (P = 0.076), and tended to be belly-nosed for a longer time (P = 0.083) compared with the reference group. In addition, in growing-finishing wk 14, pigs in the experimental group had greater scores for skin lesions (head, P = 0.001; belly, P < 0.001; caudal part, P < 0.001) and tended to be belly-nosed for a longer time (P = 0.084). In the case of pigs restricted-fed liquid feed, a greater frequency of feeding per day appears to be a condition that results in greater competitive feeding than with a lower feeding frequency.     

饲喂次数对育肥猪非采食期间行为规癖的影响

试验研究了不同饲喂次数对育肥猪行为的影响。选择平均初始体重(60.01±0.96)kg长大二元生长肥育母猪24头,分为3个处理,每个处理8个重复,每栏一头猪。3个处理分别为:①日饲喂2次;②日饲喂3次;③日饲喂4次。采用瞬时记录法,在非采食期间观察,试验期为2个月。结果表明:育肥猪在非采食期间,日饲喂2次比日饲喂3次、4次有更强的采食动机,与采食有关行为规癖的发生频率较大。     

Influence of dietary protein level, amino acid supplementation, and dietary energy levels on growing-finishing pig performance and carcass composition

Two experiments were conducted to determine the effects of feeding reduced-CP, AA-supplemented diets at two ambient temperatures (Exp. 1) or three levels of dietary NE (Exp. 2) on pig performance and carcass composition. In Exp. 1, 240 mixed-sex pigs were used to test whether projected differences in heat increment associated with diet composition affect pig performance. There were 10 replications of each treatment with four pigs per pen. For the 28-d trial, average initial and final BW were 28.7 kg and 47.5 kg, respectively. Pigs were maintained in a thermoneutral (23 degrees C) or heat-stressed (33 degrees C) environment and fed a 16% CP diet, a 12% CP diet, or a 12% CP diet supplemented with crystalline Lys, Trp, and Thr (on an as-fed basis). Pigs gained at similar rates when fed the 16% CP diet or the 12% CP diet supplemented with Lys, Trp, and Thr (P > 0.10). Pigs fed the 12% CP, AA-supplemented diet had a gain:feed similar to pigs fed the 16% CP diet when housed in the 23 degrees C environment but had a lower gain:feed in the 33 degrees C environment (diet x temperature, P < 0.01). In Exp. 2, 702 gilts were allotted to six treatments with nine replicates per treatment. Average initial and final BW were 25.3 and 109.7 kg, respectively. Gilts were fed two levels of CP (high CP with minimal crystalline AA supplementation or low CP with supplementation of Lys, Trp, Thr, and Met) and three levels of NE (high, medium, or low) in a 2 x 3 factorial arrangement. A four-phase feeding program was used, with diets containing apparent digestible Lys levels of 0.96, 0.75, 0.60, and 0.48% switched at a pig BW of 41.0, 58.8, and 82.3 kg, respectively. Pigs fed the low-CP, AA-supplemented diets had rates of growth and feed intake similar to pigs fed the high-CP diets. Dietary NE interacted with CP level for gain:feed (P < 0.06). A decrease in dietary NE from the highest NE level decreased gain:feed in pigs fed the high-CP diet; however, gain:feed declined in pigs fed the low-CP, AA-supplemented diet only when dietary NE was decreased to the lowest level. There was a slight reduction in longissimus area in pigs fed the low-CP diets (P < 0.08), but other estimates of carcass muscle did not differ (P > 0.10). These data suggest that pigs fed low-CP, AA-supplemented diets have performance and carcass characteristics similar to pigs fed higher levels of CP and that alterations in dietary NE do not have a discernible effect on pig performance or carcass composition.     

Deoxynivalenol-contaminated wheat in swine diets

Two studies were conducted using Fusarium graminearum-infected (scabby) wheat containing 6.8 ppm deoxynivalenol (DON), commonly called vomitoxin, substituted for normal wheat in starter pig diets to give varying levels of DON. After 3 wk on experimental treatments, one-half of the pigs in trial one were sacrificed to evaluate the effects of DON on heart, kidney, spleen and liver. Analyses for DON residues in these tissues were also performed. The remaining 16 pigs were placed on a conventional diet for 4 wk to evaluate effects of DON on subsequent animal performance. A different sample of scabby wheat containing 4.9 ppm of DON was substituted for sorghum grain in growing-finishing pig diets to give varying concentrations of DON. At the end of the 42-d feeding period, eight pigs were slaughtered to evaluate the effects of DON on selected tissues. Results of the three trials suggest that feed intake was reduced when DON concentrations in the swine diets neared or exceeded 1 ppm. No apparent signs of disease, including vomiting, were observed in experimental animals. Histological evaluation revealed no significant lesions or abnormalities related to DON ingestion in tissues examined. Traces of DON (8 to 28 ppb, wet weight) were found in kidney, liver, spleen and heart of starter pigs consuming the diets containing DON up to time of slaughter. No DON was found in tissues of growing-finishing pigs that were withdrawn from feed about 12 h before slaughter.     

Effect of dietary protein fluctuations and space allocation on performance and carcass quality of growing-finishing pigs

Two trials with growing-finishing pigs were conducted to evaluate the effects of fluctuating dietary CP levels and/or space allocation on performance and carcass traits. In Trial 1, three CP regimens were used with 216 growing-finishing pigs (mixed sex). Average initial and final weights of pigs were 31 and 103 kg, respectively. The CP regimens consisted of: 1) control (18% CP from wk 0 to 4; 15% CP from wk 4 to 12); 2) moderate CP variations (MCPV = 19.5% CP from wk 0 to 2, 16.5% CP from wk 2 to 6, 13.5% CP from wk 6 to 8, 16.5% CP from wk 8 to 10, 13.5% CP from wk 10 to 12); and 3) extreme CP variations (ECPV = 21% CP from wk 0 to 2, 15% CP from wk 2 to 4, 18% CP from wk 4 to 6, 12% CP from wk 6 to 8, 18% CP from wk 8 to 10, 12% CP from wk 10 to 12). Overall (wk 0 to 12), treatment differences were not observed (P > 0.05) for gain, feed intake, CP intake, gain:feed ratio, or gain/CP intake. Trial 2 involved 360 finishing pigs (mixed sex) in a 3 x 2 factorial arrangement (three dietary CP regimens, two floor space allowances). The diets consisted of: 1) control (16% CP from wk 0 to 4, 15% CP from wk 4 to 8; 14% CP from wk 8 to 12); 2) MCPV (17.5% CP from wk 0 to 2, 14.5% CP from wk 2 to 4, 16.5% CP from wk 4 to 6, 13.5% CP from wk 6 to 8, 15.5% CP from wk 8 to 10, 12.5% CP from wk 10 to 12); and 3) ECPV (19% CP from wk 0 to 2, 13% CP from wk 2 to 4, 18% CP from wk 4 to 6, 12% CP from wk 6 to 8, 17% CP from wk 8 to 10 wk, 11% CP from wk 10 to 12). Pigs were provided with either 1.12 m2 (uncrowded; five pigs/pen) or 0.56 m2 (crowded; 10 pigs/pen). Average initial weight was 49 kg and final weights were 126 kg (uncrowded) and 118 kg (crowded). Overall (0 to 12 wk), crowded pigs had lower (P < 0.05) ADG (822 vs. 916 g) and feed (as-fed) intakes (2,633 vs. 2,876 g) than uncrowded pigs. At the end of the 12-wk trial, a control vs. ECPV x space interaction (P < 0.05) occurred for weight gain, fat depth, and percentage of lean. Thus, uncrowded pigs fed ECPV gained faster (933 vs. 887 g) but had a lower percentage of lean (53.5 vs. 54.5) than controls, whereas crowded pigs on the ECPV regimen gained more slowly (812 vs. 842 g) but were leaner (54.8 vs. 54.6%) than those on the control CP regimen. Despite the wide dietary CP fluctuations, pigs in both trials consumed about the same quantity of CP during the 12-wk feeding periods. These data suggest that uncrowded pigs respond differently than crowded pigs to fluctuating levels of dietary CP.     

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.