前期高温育雏提高褐壳蛋鸡育雏成活率

褐壳蛋鸡按白壳蛋鸡温度育雏,雏鸡成活率明显低,为探讨育雏温度对褐壳蛋鸡育雏成活率的影响,笔者1988年进行了褐壳蛋鸡前期高温育雏试验.试验选择体重一致,健壮活泼的1日龄星杂579褐壳蛋雏400只,随机分成两组,每组200只,常规育雏温度(舍温33-32℃)为对照组,35-34℃高温育雏舍的一组为试验组.l-6用龄育雏温度(℃):试验组1-3日龄35-34,4-7日龄34-33,2周龄33-31,3周龄31-28,4周龄28-26,5周龄26-24,6周龄24-22;对照组1-3     

父母代海星101(公)×商品代海赛克斯(母)杂交鸡生产性能观测

用父母代海星101肉鸡公鸡与商品代海赛克斯蛋鸡母鸡杂交,其商品肉蛋杂交鸡30日龄育雏成活率96.7％:公鸡饲养70日龄体重3.14kg;母鸡56周龄产蛋量144枚。经效益分析,繁育、推广海星101肉鸡×海赛克斯蛋鸡杂交鸡,在农村专业户低档日粮条件下每只商品鸡刨毛利润10.41元,比同等条件下饲养红宝×罗曼杂交鸡多创收2.0元。     

父母代红宝肉用公鸡与商品代罗曼蛋用母鸡的杂交试验

本试验以1508只商品代罗曼蛋鸡（♀）与150只代红宝肉鸡（♂）间杂交。其生产母鸡（21周龄至淘汰的鸡）36周平均产蛋率76．43％；种蛋授精率92．6％，受精蛋孵化率74．42％；商品杂交鸡30日龄内育雏成活率93．7％；商品公鸡饲养70日龄体重2.85kg，商品母鸡56周龄产蛋量128枚。     

微胶囊包膜缓释植物精油在蛋鹌鹑上的应用效果及使用方案研究

本试验以蛋鹌鹑为研究对象,旨在探究不同梯度微胶囊包膜缓释植物精油在蛋鹌鹑中的应用效果,为微胶囊包膜缓释植物精油在蛋禽的使用剂量提供参考方案。试验选取4月龄的蛋鹌鹑6615只,分为7个处理,每个处理3个重复,每个重复315只鹌鹑。负对照组为基础日粮,对照组添加50ppm硫酸粘杆菌素,试验1-3组分别添加微胶囊包膜缓释植物精油50ppm、100ppm、200ppm,试验4组添加50ppm微胶囊包膜缓释植物精油+20ppm恩拉霉素,试验5组添加400ppm天然植物精油,预饲期为5d,试验期为40d。试验结果表明:试验3组(200ppm微胶囊包膜缓释植物精油)和试验4组(50ppm微胶囊包膜缓释植物精油+20ppm恩拉霉素)蛋鹌鹑的平均日产蛋重显著高于负对照组和对照组(50ppm硫酸粘杆菌素)(<0.05),平均日采食量、产蛋率、料蛋比和成活率均优于负对照组和对照组(50ppm硫酸粘杆菌素)(>0.05);试验2组(100ppm微胶囊包膜缓释植物精油)、试验3组(200ppm微胶囊包膜缓释植物精油)和试验4组(50ppm微胶囊包膜缓释植物精油+20ppm恩拉霉素)鹌鹑的正常粪便比例最高,高于负对照组和对照组(50ppm硫酸粘杆菌素)(>0.05);随着微胶囊包膜缓释植物精油添加剂量的增加,蛋鹌鹑的平均日采食量、平均日产蛋重和产蛋率有线性增加的趋势,利用回归方程计算,当微胶囊包膜缓释植物精油剂量为95ppm时,蛋鹌鹑的平均日采食量和平均日产蛋重可以达到50ppm硫酸粘杆菌素水平,当微胶囊包膜缓释植物精油剂量≥139ppm时,蛋鹌鹑产蛋性能和产蛋率可优于50ppm硫酸粘杆菌素。因此,蛋禽日粮中的微胶囊包膜缓释植物精油可以完全替代抗生素,推荐使用剂量为100ppm^150ppm。以30万只蛋鹌鹑场为例,饲粮中添加100ppm微胶囊包膜缓释植物精油与未添加组相比,每年可增加净利润8.395万元,经济效益非常可观。     

高温季节在日粮中添加杆菌肽锌对樱桃谷肉鸭生产性能的影响

将7月6日出壳的1530只商品代樱桃谷鸭雏分成3组进行饲养试验。试验Ⅰ组从21日龄开始在日粮中添加50×106杆菌肽锌,试验Ⅱ组从1日龄开始在日粮中添加50×106杆菌肽锌,对照组不添加杆菌肽锌。结果表明,在日粮中添加杆菌肽锌,育雏期樱桃谷小鸭的生长速度提高10.27%,饲料转化率提高8.26%,效果显著(P<0.01),但采食量没有显著变化;育成育肥期樱桃谷肉鸭的生长速度与育雏期日粮未添加与添加杆菌肽锌组相比,分别提高9.55%、7.25%,饲料转化率分别提高3.23%、4.23%,日均采食量分别提高5.98%、2.83%;成活率差异不显著(P>0.05)。     

硫酸亚铁脱毒棉籽饼对蛋鸡繁殖性能影响的研究

用含游离棉酚(FG)100ppm、150ppm、200ppm添加和不添加硫酸亚铁的棉籽饼日粮,与含FG50ppm、100ppm硫酸亚铁溶液浸泡脱毒棉籽饼日粮,先后两次进行了长期饲喂育成鸡和成年公母鸡的试验。结果表明,各试验日粮中的游离棉酚对育成鸡的生长发育和性成熟,对成年母鸡的产蛋和种蛋率受精率,以及对成年公鸡的精液品质和配种能力,均无不良影响;但对受精蛋出雏率影响显著,蛋中游离棉酚残毒含量与受精蛋出雏率呈强负相关(r=-0.79)。硫酸亚铁干拌棉籽饼较原饼具有提高孵化率的效果,但不理想。硫酸亚铁干拌棉籽饼脱毒效果不如硫酸亚铁溶液浸泡脱毒效果。硫酸亚铁中铁占日粮的220ppm时,母鸡500日龄产蛋量降低。     

饲粮不同硒水平对22～42日龄黄羽肉鸡生长性能、抗氧化指标的影响

试验旨在研究饲粮不同硒水平对22~42日龄黄羽肉鸡生长性能、抗氧化指标的影响,从而确定快大型黄羽肉鸡饲养中期的最适硒水平。选用22日龄健康、发育良好的快大型岭南黄羽肉公雏鸡1 200只,根据体重随机分为5个组,每组6个重复,每个重复40只,试验组1(对照组)为基础日粮组(硒含量0.037 mg/kg),试验组2、3、4、5饲粮则在基础日粮中分别添加0.075、0.15、0.225、0.30 mg/kg硒,试验期为21 d。结果表明:饲粮添加不同水平硒对试验鸡生长性能无显著影响(P0.05);各硒添加组血浆、红细胞和肝脏谷胱甘肽过氧化物酶(GSH-Px)活力显著高于对照组(P0.05),饲粮添加不同水平硒对试验鸡血浆和肝脏丙二醛(MDA)含量无显著影响(P0.05)。综合考虑,22~42日龄黄羽肉鸡饲粮硒适宜水平为0.337 mg/kg。     

绿壳蛋鸡的引种养殖与效益分析

引进绿壳蛋鸡AE型1日龄雏鸡5000羽，育雏期（1～50日龄）采用地面平养方式饲养，按常规方式育雏；育成期（51～150日龄）采用放牧补料方式饲养，适当降低日粮蛋白质的能量浓度，进行限制饲养；产蛋期采用放牧补料方式饲养，按常规免疫接种。经150d的育雏和育成期饲养，羽均重达1．45kg，料重比为2．785：1，成活率达95．28％；64周龄羽均产蛋191枚（8．977kg），料蛋比为2．76：1。经试验，饲养绿壳蛋鸡至64周龄出栏淘汰，每羽可盈利91．38元，比饲养安吉土鸡净利润提高143．03％。     

育雏期鸡病防治顺序排行榜

鸡的育雏期(蛋鸡0～6周龄、肉鸡0～4周龄)是其一生中最关键的时期。养殖者能否获得应有的经济效益,取决于育雏阶段的饲养管理和疾病防治水平。鸡在育雏期内因疾病造成的死亡,占整个饲养期的30％以上,稍有不慎,就会造成惨重的损失。就蛋鸡群而言,在整个饲养期内,如死亡率达到30％,那么无论其产蛋率多高,都将无利可图。 育雏期的鸡病多达数10种,常见的就有20余种,而在育雏期需要预防的疾病还远不止这些。 鸡白痢。1～3日龄即可发生并导致鸡只死亡,     

品种与日粮营养水平对鸡内脏器官质量及指数的影响

试验选取30日龄的云南茶花鸡、武定鸡、盐津乌鸡、AA肉鸡和土杂鸡等96只鸡,随机分为3组,分别饲喂3种不同的蛋白水平日粮,即16.5%、18%和19.5%,探讨日粮蛋白水平对30～60日龄的云南部分地方鸡、肉鸡及土杂鸡内脏器官指数的影响。试验结果表明:品种对各内脏质量及其指数均有显著的影响。肉鸡和土杂鸡的内脏器官质量显著高于云南地方鸡种,而地方鸡的总内脏指数、肠指数、胃指数、肝指数、心脏指数和肺指数均高于肉鸡和土杂鸡(P0.05)。品种间内脏指数随活质量的降低而增加。日粮蛋白水平对内脏质量及其指数的影响不显著。     

Effects of 4,4'-dimethyldiphenyliodonium chloride on performance of growing cattle

Two 112-d studies were conducted to evaluate effects of the deaminase inhibitor, 4,4'-dimethyldiphenyliodonium chloride, on performance of growing cattle. With diets containing low levels of crude protein (i.e., 11%), 25 ppm of chemical in the diet increased (P less than .05) gain and improved (P less than .05) feed efficiency. Feed intake was not affected. Higher levels of chemical (50 and 100 ppm) produced equivalent responses. With a higher level of dietary crude protein (i.e., 14%) gain and feed efficiency were not improved and some decreases in feed intake were observed. Performance responses resulting from adjustments in ruminal nitrogen transactions to provide more alpha-amino-N depend upon whether the animal needs additional amino acids for maintenance and production. Our data demonstrated that the supply of amino acids can be increased either by adjustment of ruminal nitrogen transactions with a chemical agent or by increasing concentration of dietary protein.     

Additional dietary zinc for weaning piglets is associated with elevated concentrations of serum IGF-I

Two experiments were performed in order to study how weaning and post-weaning dietary zinc level affect serum IGF-I. Further, whether the growth-enhancing effect of 2500 ppm of dietary zinc (Zn2500) and/or 175 ppm of dietary copper (Cu175) in post-weaning diets is associated with elevated serum IGF-I levels in piglets was studied. Experiment 1 included 54 piglets (six litters of nine piglets). One piglet from every litter was assigned to a control group (blood sampled 1 day before weaning). At weaning the remaining eight piglets from every litter were allocated randomly to four dietary treatments with increasing zinc inclusions (Zn100, Zn250, Zn1000, Zn2500). In exp. 2, 48 piglets (six litters of eight piglets) were allocated to four dietary treatments (Zn100, Zn100Cu175, Zn2500, Zn2500Cu175). All piglets in exp. 1 were blood sampled at -1, 1-2, 5-6 or 14-15 days after weaning and in exp. 2 blood samples were taken from all pigs 5-7 days after weaning. Feed intake was recorded per pen (two piglets) and weight gain was recorded for every piglet. Just after weaning feed intake was very low, piglets lost weight and serum IGF-I decreased in exp. 1. However, the piglets fed 2500 ppm of zinc reached pre-weaning levels of serum IGF-I at 14-15 days post-weaning, whereas piglets receiving lower zinc levels showed no changes in serum IGF-I. In exp. 2, additional dietary zinc in weaning diets for piglets was found to be associated with increased feed intake, improved growth rate and increased serum IGF-I. High levels of dietary copper did not affect any of these measurements. Zinc-induced rise in serum IGF-I was partly due to increased feed intake. After correcting for differences in feed intake, zinc significantly increased serum IGF-I. However, to completely separate effects of feed intake from effects of zinc status, pair-feeding should be considered in future studies.     

Effect of different dietary levels of Yucca schidigera powder on the performance,blood parameters and egg yolk cholesterol of laying quails

A total of 135 laying quails (Coturnix coturnix japonica), 9 weeks old, were divided into three dietary treatment groups. Three replicates were assigned to each treatment group consisting of 15 birds per cage. The diet was supplemented with 0, 100 and 200 ppm Yucca schidigera powder and given ad libitum to the quails for a period of 14 weeks. Body weight, egg production, feed consumption and feed efficiency were not different due to dietary treatments among the groups. Increased egg weight was determined in the control group. Yucca powder supplementation decreased serum glucose, cholesterol triglyceride level in laying quails. Serum total protein concentration was not changed by dietary treatments but albumin level was decreased in quails fed 100 ppm yucca powder. Egg yolk cholesterol concentration was not significantly different among the groups but tended to decline (11.5%) as a result of yucca supplementation. Red Blood Cell (RBC) and White Blood Cell (WBC) counts, packed cell volume (PCV), mean corpuscular volume (MCV) and mean corpuscular haemoglobin (MCH) were not affected by supplementation of yucca powder. However, haemoglobin (HB) concentration was slightly increased and mean corpuscular haemoglobin concentration (MCHC) was significantly increased by 200 ppm yucca powder supplementation to the diet.     

Interactive effects of dietary calcium, phosphorus and copper on performance and liver stores of pigs

Three experiments involving 304 pigs were conducted to determine the related effects of copper (Cu), calcium (Ca) and phosphorus (P) on the performance and liver Cu stores of growing-finishing pigs. Rate and efficiency of gain were improved by the addition of 250 ppm of Cu to the diets. Improvements in rate of gain averaged 6.6% (652 vs 696 g/d) to 60.5 kg body weight and 1.7% (713 vs 725 g/d) to 94.5 kg body weight. Feed:gain ratio was improved by 1.4% to 60.5 kg and 1.6% to 94.5 kg body weight when Cu was added to the diet. Increasing the dietary Ca and P levels from .65% Ca and .55% P to 1.2% Ca and .86 or 1.0% P resulted in increased (P less than .01) growth rate to 60 and 95 kg (649 vs 699 g/d and 700 vs 737 g/d, respectively), but feed efficiency was not affected (2.86 vs 2.84 and 3.18 vs 3.17 kg feed/kg gain, respectively.) Feeding the higher Ca and P levels resulted in increased liver Cu levels in pigs fed 250 ppm Cu (189 vs 323 ppm), but Ca and P did not affect liver Cu of pigs fed low Cu diets (29 vs 28 ppm). When dietary Ca and P were varied independently, the high Ca level increased liver Cu, but P had little effect on liver Cu. Increasing the dietary P level partially alleviated the effect of Ca on liver Cu.     

Effects of source and level of copper on performance and liver copper stores in weanling pigs

Five 28- to 33-d experiments involving 460 crossbred pigs weaned at 28 +/- 2 d of age (initial weight, 6.7 to 8.1 kg) were conducted to determine the effects of feeding high dietary levels of Cu sulfate (CuSO4) or Cu oxide (CuO) on rate and efficiency of gain and liver Cu stores of weanling pigs. The pigs were housed in groups of five to six/pen and fed a fortified, unmedicated, corn-soybean meal-dried whey basal diet (1.1% lysine, 30 ppm Cu). In Exp. 1 and 2, pigs (eight replicates) were fed the basal or the basal plus 125 or 250 ppm Cu from CuSO4 or CuO for 28 d. In Exp. 3 and 4, four replications were fed the same diets as in Exp. 1 and 2 plus two additional diets (500 ppm Cu from CuSO4 or CuO). In Exp. 5, dietary levels of 0, 125, 250, 375 or 500 ppm Cu from CuSO4 were evaluated using four replications. At the end of each experiment, the liver from one pig in each pen was collected for Cu analysis. Overall, rate and efficiency of gain were improved (P less than .01) by feeding 125 or 250 ppm Cu as CuSO4, with the 125 ppm dietary level being about 75% as effective in stimulating growth as 250 ppm. Performance of pigs was not different from controls when the highest (500 ppm) level of Cu (from CuSO4) was fed. Liver Cu increased 10- to 70-fold when 250 to 550 ppm Cu from CuSO4 was included in the feed.(ABSTRACT TRUNCATED AT 250 WORDS)     

Efficacy of Three Potential Alternatives to Antimicrobial Feed Additives for Weanling Pigs

Three 5-wk growth trials involving 288 weanling pigs were conducted to assess the efficacy of three feed additives as alternatives to antimicrobial feed additives. In Trial 1, a mannanoligosaccha-ride (MOS) source was evaluated with the antimicrobial feed additive carbadox. Treatments included 1) a control diet, 2) a diet containing MOS (0.3% during wk 1 and 0.2% for wk 2 through 5), 3) a diet containing carbadox (55 ppm), and 4) a diet containing both additives. For the 5-wk trial, ADG was 446, 450, 489, and 489 g, and ADFI was 770, 769, 840, and 826 g for Treatments 1 through 4, respectively. No effects of MOS supplementation and no interaction effects of MOS and carbadox were observed (P>0.40). Dietary addition of carbadox resulted in an 8% increase in feed consumption and a 9% improvement in growth rate (P<0.01). In Trial 2, a probiotic consisting of Bacillus licheniformis and subtilis was assessed. Treatments included 1) a control diet, 2) a diet containing Bacillus additive (0.1%), 3) a diet containing carbadox (55 ppm), and 4) a diet containing both additives. Overall ADG was 483, 458, 521, and 503 g, and ADFI was 779, 759, 818, and 795 for Treatments 1 through 4, respectively. Overall there was no Bacillus × carbadox interaction (P>0.40). A slight reduction in growth rate with Bacillus supplementation was observed (P<0.05). Carbadox improved growth rate by 9% and improved feed conversion efficiency by 4% (P<0.01). In Trial 3, increasing dietary levels of a polyaspartate biopolymer product (PAB) (0, 100, 200, and 400 ppm) were assessed. Overall ADG was 502, 491, 491, and 513 g, and ADFI was 889, 836, 823, and 866 for the 0, 100, 200, and 400 ppm PAB treatments, respectively. There was a quadratic change in ADFI with increasing PAB level (P<0.06), but no other effect of PAB was observed. Under the conditions of these trials, no improvements in growth performance with the alternative feed additive products were observed. The antimicrobial feed additive carbadox was effective in improving weanling pig growth performance.     

Optimum ratio of histidine in the piglet ideal protein model and its effects on the body metabolism. II. Optimum ratio of histidine in 10-20 KG piglet ideal protein and its effects on blood parameters.

Two growth trails were conducted to determine the optimum ratio of histidine in 10-20 kg piglet ideal protein model. Four diets containing 0.23%, 0.31%, 0.39% and 0.47% digestible histidine (0, 0.08%, 0.16%, 0.24% crystalline histidine supplemented into the basal diet) were fed to 96 piglets of mean initial body weight 10.3 +/- 1.08 kg for 18 d in Experiment 1. Average daily gain, average daily feed intake and feed conversion efficiency were inhibited (P < 0.05) with the diet containing 0.23% digestible histidine. Performance was maximized with 0.31% digestible histidine. As the dietary histidine increased, blood urea nitrogen and serum cholesterol concentration were influenced significantly. The concentrations of serum histamine and free histidine did not change with increase in digestible histidine from 0.23 to 0.31%, but higher supplementation resulted in a significant linear increase in both serum parameters. It was concluded that the dietary level of 0.23% digestible histidine does not meet the requirement of 10-20 kg piglets. Based on the results from Experiment 1, Experiment 2 was designed to determine the optimum ratio of lysine:histidine in the ideal protein model of 10-20 kg piglet. Ninety-six Large White x Landrace piglets weighing 10.2 +/- 0.88 kg were divided into 4 groups. They were fed four diets containing 0.26, 0.29, 0.32 or 0.35% digestible histidine, formulated by adding 0.03, 0.06, 0.09 or 0.12% crystalline histidine to the basal diet. The trial lasted for 21 days. Results showed that performance was significantly improved with 0.32 and 0.35% digestible histidine. As dietary histidine increased, blood urea nitrogen tended to decrease but not significant at P < 0.05. Serum cholesterol concentration increased with an increase in dietary histidine level and reached a maximum at 0.35%. Serum histamine increased with increasing dietary histidine. Free serum histidine increased linearly with increased dietary histidine. From both experiments it was concluded that the digestible histidine requirement for 10-20 kg piglets was 0.31% and that the optimum ratio of dietary lysine to histidine should be 100:30. The concentrations of cholesterol, histamine and free histidine in serum were sensitive parameters to measure changes in dietary histidine levels.     

Effects of copper supplementation on feedlot performance, carcass characteristics, and rumen sulfur metabolism of growing cattle fed diets containing 60% dried distillers grains

The effects of 3 supplemental Cu concentrations on feedlot performance, mineral absorption, carcass characteristics, and ruminal S metabolism of cattle fed diets containing 60% dried distillers grains with solubles (DDGS) were evaluated in 2 experiments. Experiment 1 was conducted with 84 Angus-cross yearling steers and heifers (initial BW = 238 ± 36 kg), which were blocked by gender and allocated to 12 pens. Supplemental dietary Cu (tribasic copper chloride) treatments were: 1) 0 mg Cu/kg diet DM, 2) 100 mg Cu/kg diet DM, 3) 200 mg Cu/kg diet DM. The remainder of the diet was DDGS (60%), grass hay (10%), pelleted soy hulls (15%), and a vitamin-mineral supplement (15%). Diets were offered ad libitum throughout the finishing phase (168 d). Three cattle from each pen (n = 36) were harvested on d 168 and carcass data and liver samples were collected. Copper supplementation did not affect ADG (P = 0.22). However, the nonsignificant trend for increased ADG and decreased DMI led to a linear increase (P = 0.02) feed efficiency (G:F = 0.167, 0.177, and 0.177 for 0, 100, and 200 mg Cu/kg diet DM, respectively). The apparent absorption of Cu decreased quadratically (P = 0.07) and the apparent absorption of Mn and Zn were decreased linearly (P = 0.03 and P = 0.05, respectively) with increased Cu supplementation. Cattle supplemented with 100 or 200 mg Cu/kg diet DM had greater liver Cu concentrations (P < 0.01) than cattle that were not supplemented with Cu. There were no treatment effects (P > 0.10) on HCW, LM area, USDA yield grade, backfat, or marbling score. Experiment 2 was conducted with 6 ruminally fistulated steers that were fed the same diets as in Exp 1 in a replicated 3 × 3 Latin Square design. Copper supplementation did not affect (P > 0.10) ruminal pH or liquid S(2-) concentrations in steers consuming 60% DDGS diets (total dietary S = 0.55%). From 3 to 9 h after feeding, H(2)S gas concentration was decreased in those cattle supplemented with 100 mg Cu/kg diet. Concentration of H(2)S gas did not differ among cattle supplemented with 0 or 200 mg Cu/kg diet DM on 60% DDGS diets. Supplemental Cu improved feed efficiency in cattle consuming diets containing 60% DDGS; however, effects of Cu on rumen S metabolism were minimal even when supplemented at twice the maximum tolerable limit for beef cattle (NRC, 2000).     

Effect of potassium diformate in combination with different amounts and sources of excessive dietary copper on production performance in weaning piglets.

Three studies with each 96 weaning piglets were conducted to evaluate the combinatory effect of potassium diformate and high dietary doses of Cu on production performance. In Exp. 1, increasing dietary Cu (25, 75, 125, 175 ppm Cu) were tested at either no or 1.8% potassium diformate. In Exp. 2, rising dietary levels of potassium diformate (0%, 0.6%, 1.2% and 1.8%) were tested at either 25 or 175 ppm Cu. In Exp. 3, a basal dietary Cu content of 15 ppm was compared with dietary Cu levels of 95 or 175 ppm, each of them added as either Cu sulphate or Cu amino acid chelate or Cu formate. Rising dietary additions of potassium diformate and Cu improved weight gain, feed intake and feed conversion rate of piglets. The combination of potassium diformate and Cu failed to act additively at highest dose levels of the two supplements. Cu sulphate was efficient as growth stimulating additive in all 3 experiments, Cu formate failed to stimulate production performance. Cu chelate tended to depress production performance and to increase blood plasma Cu compared to equivalent amounts of Cu from Cu sulphate.     

Effects of increasing dietary L-carnitine on growth performance of weanling pigs

Four experiments were conducted to evaluate the effects of supplementing graded levels (0 to 100 ppm) of L-carnitine to the diet of weanling pigs on growth performance during a 34- to 38-d experimental period. A fifth experiment was conducted to determine the effects of addition of L-carnitine to diets with or without added soybean oil (SBO) on growth performance. In Exp. 1, 128 pigs (initial BW = 5.5 kg) were allotted to four dietary treatments (six pens per treatment of four to six pigs per pen). Dietary treatments were a control diet containing no added L-carnitine and the control diet with 25, 50, or 100 ppm of added L-carnitine. In Exp. 2, 3, and 4, pigs (4.8 to 5.6 kg of BW) were allotted to five dietary treatments consisting of either a control diet containing no added L-carnitine or the control diet with 25, 50, 75, or 100 ppm of added L-carnitine. All diets in Exp. 1 to 4 contained added soybean oil (4 to 6%). There were seven pens per treatment (four to five pigs per pen) in Exp. 2, whereas Exp. 3 and 4 had five and six pens/treatment (eight pigs per pen), respectively. In general, dietary carnitine additions had only minor effects on growth performance during Phases 1 and 3; however, dietary L-carnitine increased (linear [Exp. 1], quadratic [Exp. 2 to 4], P < 0.03) ADG and gain:feed (G:F) during Phase 2. The improvements in growth performance during Phase 2 were of great enough magnitude that carnitine addition tended to increase ADG (linear, P < 0.10) and improve G:F (quadratic, P < 0.02) for the entire 38-d period. In Exp. 5, 216 weanling pigs (5.8 kg of BW) were allotted (12 pens/treatment of four to five pigs per pen) to four dietary treatments. The four dietary treatments were arranged in a 2 x 2 factorial with main effects of added SBO (0 or 5%) and added L-carnitine (0 or 50 ppm). Pigs fed SBO tended (P < 0.07) to grow more slowly and consumed less feed compared with those not fed SBO, but G:F was improved (P < 0.02). The addition of L-carnitine did not affect (P > 0.10) ADG or ADFI; however, it improved (P < 0.03) G:F. Also, the increase in G:F associated with L-carnitine tended to be more pronounced for pigs fed SBO than those not fed SBO (carnitine x SBO, P < 0.10). These results suggest that the addition of 50 to 100 ppm of added L-carnitine to the diet improved growth performance of weanling pigs. In addition, supplemental L-carnitine tended to be more effective when SBO was provided in the diet.