乳清粉含量对刚断奶仔猪生产性能的影响

研究不同水平的乳清粉 (5 %、10 %、20 % )对刚断奶仔猪生产性能的影响 ,结果表明 :随乳清粉水平的增加 ,仔猪生产性能随着增加 ,尤其是刚断奶后2周 ,各组间日增重差异显著 (P<0.05) ,日采食量20 %乳清粉组较5 %和10 %乳清粉组分别提高15.96 %和19.71 %,饲料增重比随乳清粉水平的增加呈现降低趋势。在整个试验期 ,各组间日增重达显著水平 (P=0.02) ,日采食量接近显著水平 (P=0.08) ,饲料增重比10 %和20 %乳清粉组较5 %乳清粉组分别降低15.71 %和22.82 %。从经济效益上分析 ,以20 %乳清粉组最佳。     

乳清粉对刚断奶仔猪消化机能的影响研究

本试验研究了不同水平的乳清粉对刚断奶仔猪消化性能的影响。试验根据乳清粉含量（5，10，20％），设3个处理。结果表明：营养物质消化率均随乳清粉水平的提高而提高，其中干物质和粗脂肪均达到显著水平（P＜0．05）；粗蛋白和无氮浸出物消化率均随乳清粉水平提高而呈上升趋势，但差异不显著（P＞0．05）；乳清粉含量由5％升至20％，腹泻率依次降低，但差异不显著（P＞0．05）；粪便大肠杆菌数随乳清粉水平的提高呈下降趋势，差异显著（P＜0．05），各组间乳酸直菌数差异显著（P＜0．05），以含20％乳清粉的处理组最高，与其他两个组比较，差异均达显著水平（P＜0．05）。     

谷氨酰胺在断奶仔猪饲料中的应用效果

选取108头28日龄杜大长三元杂交断奶仔猪,按饲养试验随机分成3组,每组设3个重复,每个重复12头。Ⅰ组为5%乳清粉日粮组、Ⅱ组为0.5%谷氨酰胺二肽日粮组、Ⅲ组为2%乳清粉+0.5%谷氨酰胺二肽日粮组。试验从28日龄开始至52日龄时结束,试验期为24d,进行断奶仔猪日粮中添加谷氨酰胺对提高断奶仔猪生长性能的试验研究。试验结果表明:Ⅱ组(0.5%谷氨酰胺二肽)比对照Ⅰ组(5%乳清粉)平均日增重提高了3.8%,差异不显著(P>0.05);Ⅲ组(0.5%谷氨酰胺二肽+2%乳清粉)比对照Ⅰ组(5%乳清粉)平均日增重提高了19.2%(P<0.05),增重效果显著。这表明断奶仔猪日粮中添加0.5%谷氨酰胺二肽可替代5%的乳清粉,谷氨酰胺和乳清粉联合使用(用0.5%的谷氨酰胺二肽替代3%的乳清粉)对断奶仔猪来说能取得更理想的饲养效果,并且显著降低了饲料成本。在饲料报酬和采食量方面,Ⅱ组(0.5%谷氨酰胺二肽)与对照Ⅰ组(5%乳清粉)相比饲料转化率降低了1.17%,差异不显著(P>0.05);Ⅲ组(0.5%谷氨酰胺二肽+2%乳清粉)与对照Ⅰ组(5%乳清粉)相比饲料转化率提高了9.25%,差异显著(P<0.05)。表明谷氨酰胺能改善仔猪肠道功能,增加营养物质的吸收,谷氨酰胺与乳清粉联合使用可显著提高饲料转化率,同时可促进仔猪的采食量。在仔猪腹泻方面,试验各组的断奶仔猪均保持在一较低水平的腹泻率,并且差异不显著(P>0.05)。     

日粮中添加甲酸钙和酸性蛋白酶对断奶仔猪生产性能的影响

本研究探讨玉米 豆粕 乳清粉型日粮中添加甲酸钙和酸性蛋白酶对断奶仔猪生产性能的影响 ,试验采用 2× 2完全随机设计 ,2 8d研究表明 :1%甲酸钙极显著提高日增重 (P <0 .0 1)、仔猪采食量 (P <0 .0 5 ) ,显著降低仔猪断奶后腹泻频率 (P <0 .0 5 )、结肠Coliform总数 (P <0 .0 5 ) ;0 .2 %酸性蛋白酶显著提高 (P <0 .0 5 )饲料转化率、显著降低仔猪断奶后腹泻频率 (P <0 .0 5 )、结肠Coliform总数 (P <0 .0 5 ) ;两者在提高仔猪采食量 (P <0 .0 5 )上存在协同效应 ;酸性蛋白酶和甲酸钙降低商品猪生产成本 ,提高猪肉生产经济效益     

日粮中添加亚麻籽对肉羊消化代谢的影响

16只体重相近,均值为(34.06±1.68)kg的杂交公羔羊按单因素随机设计原理被分成4组,每组4只,日粮中添加0%,5%,10%,15%亚麻籽进行消化代谢试验,研究不同水平的亚麻籽对绵羊消化代谢的影响。结果表明:随着亚麻籽添加水平的提高,干物质的采食量表现下降的趋势,但干物质的表观消化率各组间没有差异(P>0.05);亚麻籽的含量与可消化氮和沉积氮呈现负相关趋势,氮的表观消化率各组间差异显著(P<0.05),呈现逐渐递减的现象;有机物的表观消化率变化幅度不大,前3组差异不显著(P>0.05),添加15%亚麻籽的Ⅳ组与其他组比较差异显著;粗脂肪的表观消化率与亚麻籽的添加水平呈正相关,且各组间表现显著;纤维类物质中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)随着亚麻籽添加水平的增加而表现大幅度的下降,各组间差异显著(P<0.05)。     

大麦型日粮中添加非淀粉多糖酶对仔猪生长和消化性能的影响

以“杜长嘉”杂交仔猪为对象 ,研究大麦型饲粮中添加NSP酶制剂对仔猪生长性能和消化率的影响。结果表明 :与对照组相比 ,添加NSP酶使仔猪日增重提高 1 1 .54% (P <0 .0 1 ) ,饲料转化率提高5.33% (P <0 .0 5) ,日采食量提高 5.4 0 % (P <0 .0 5)。添加NSP酶可显著提高各种营养物质的消化率 ,与对照组相比 ,干物质、粗蛋白、粗脂肪、粗纤维、粗灰分和无氮浸出物的表观消化率分别提高 5.56% (P <0 .0 1 )、4 .79% (P <0 .0 1 )、2 8.79% (P <0 .0 1 )、1 5.0 5% (P <0 .0 1 )、32 .0 5% (P <0 .0 1 )和 4 .2 4 % (P <0 .0 1 )。     

谷氨酰胺与乳清粉对SEW仔猪生长性能影响的对比试验

试验选取72头25日龄断奶仔猪，按母猪胎次、窝别、体重随机分为2组：1％百做维 5％乳清粉、10％乳清粉。每组没3个重复，每重复12头。试验结果表明：仔猪在28.43日龄段的平均日增重1％百傲维 5％乳清粉组比10％乳清粉组提高了7．1％(P＞0.05)。1％百傲维 5％乳清粉组仟猪采食量比10％乳清粉组提高6.4％(P＞0．05)。43—51日龄平均日增重1％百傲维 5％乳清粉组比10％乳清粉组提高了14．4％(P＜0．05)。仟猪采食量比10%乳清粉组提高11．7％(P＜0．05)。28—51日龄平均日增重1％百傲维 5％乳清粉组比10％乳清粉组提高了9．8％(P＜0．05)。仔猪采食量比10%乳清粉组提高5．5％(P＞0．05)。各处理组的料重比基本一致(P＞0．05)，腹泻率各组均在较低水平(P＞0．05)。本次试验表明：以1％百傲维 5％乳清粉取代10％乳清粉是可行的。     

哺乳仔猪饲料中无乳清粉配方研究

1991年6～9月,用杜洛克×大约克的F_1177头仔猪,在同一营养水平的基础上,分别用4％葡萄糖、0％乳清粉(T1组);0％葡萄糖、4％乳清粉(T2组);2％葡萄糖、2％乳清粉(T3组),进行葡萄糖替代乳清粉试验。 结果:(1)各组5日龄全部采食。35日龄断奶。消化正常。(2)60日龄试验结束:a.个体重T1组18.85±0.31kg;T2组20.47±0.39kg;T3组18.61±0.24kg,各组差异不显著(P>0.05)。b.育成率:T1组100％;T2组95.65％;T3组93.75％。(3)试验证实:葡萄糖完全可以替代乳清粉。 葡萄糖国产资源广阔丰富,从而避免仔猪颗粒饲料生产局限依赖进口乳清粉,经济效益显著。     

乳清粉在断奶仔猪上的应用研究

乳清粉是生产奶酪及酪蛋白时所得的副产品,主要成分是乳糖、乳蛋白和矿物质.近年来,由于乳制品工业的发展以及我国养猪和奶牛生产水平的提高,乳清粉已成为幼畜生产必不可少的原料.本试验旨在评估乳清粉在保育期仔猪生产上的应用效果.将60头断奶仔猪日粮分为3个阶段,各处理组日粮分别为:1)对照组(不含乳糖)；2)低含量乳清粉；3)高含量乳清粉.在试验中,仔猪3个阶段日粮的乳清粉高低含量分别是阶段1 (25%和12.5%)、阶段2(20%和10%)、阶段3(12%和6%).结果显示,在阶段1的试验中,饲喂乳清粉组较对照组可明显增加仔猪的ADG和ADFI;在阶段2和阶段3中,各处理组仔猪的ADG、ADFI和G:F均没有显著差异(P＞0.10).综上所述,当给仔猪饲喂乳清粉日粮可较对照组明显改善断奶仔猪的生产性能.     

高产泌乳母猪饲粮蛋白质与赖氨酸参数的研究

以产活仔 1 2头以上的经产母猪为对象 ,研究蛋白质水平分别为 1 1 .5 %、1 3 .8%、1 5 .9%、1 8.0 %和2 0 .2 % ,相应的赖氨酸为 0 .61 %、0 .74 %、0 .87%、1 .0 %和 1 .1 2 %的 5种等能饲粮对母猪繁育、泌乳及血浆尿素氮和游离氨基酸含量的影响。结果表明 :随着蛋白质和赖氨酸摄入量的提高 ,母猪泌乳期失重减少 (P <0 .0 5 ) ,泌乳量则显著提高 (P <0 .0 5 )。仔猪 2 0和 3 5日龄的窝重均显著受母猪饲粮营养水平的影响 (P <0 .0 5或P <0 .0 1 )。血浆尿素N随蛋白质和赖氨酸水平的提高而提高 (P <0 .0 5 ) ,但血浆游离氨基酸总含量无显著差异。无论母猪繁育效果和泌乳性 ,均以第 4组饲粮即母猪日摄入蛋白质 868g,赖氨酸 4 8.3g时 ,获得了最佳效果     

Effect of protein and(or) carbohydrate fractions of dried whey on performance and nutrient digestibility of early weaned pigs

One hundred eighty 3-wk-old pigs (initial weight 4.8 kg) were utilized in a 35-d growth trial to determine the effects of the carbohydrate and(or) protein fraction of dried whey on pig performance. In addition, 30, 3-wk-old pigs (initial weight 4.9 kg) were used in two digestion trials to study the effects of the whey fraction on nutrient digestibility. Dietary treatments included a corn-soybean meal diet (control), control + 20% dried whey, control + 14.4% lactose, control + 2.1% lactalbumin, control + 14.4% lactose + 2.1% lactalbumin, and control + 8.4% whey protein concentrate. Pelleted diets containing equal lysine concentrations were fed. Lactose and lactalbumin were added at the same levels as provided by a 20% dried whey diet. Pigs fed diets containing milk products exhibited superior (P less than .05) ADG and efficiency of feed utilization and greater (P less than .05) apparent digestibilities for DM, energy and N compared with pigs fed the control diet. Including either lactose or lactalbumin in the diet for the early weaned pig resulted in similar gain, feed efficiency and nutrient digestibility. These results indicate that both the carbohydrate (lactose) and protein (lactalbumin) fractions of dried whey are important in explaining the beneficial response to dried whey elicited in the weanling pig.     

An evaluation of barley in starter diets for swine

Four growth trials and one digestibility trial were conducted to determine the effects of substituting barley for grain sorghum in weanling pig diets on pig performance and nutrient digestibility. Experiments 1 and 2 were 35-d growth trials in which barley was substituted for gain sorghum at levels of 0, 10, 20, 30 and 40% of the diet. Average daily gain (ADG), average daily feed intake (ADFI) and feed conversion (F/G) were not affected by dietary barley level (P greater than .50). Experiment 3 was a digestibility trial conducted to determine the apparent digestibility of dry matter (DMD), gross energy (GED), and N (ND) and percentage of N retained (%NRT) of pigs fed the 0, 20 and 40% barley diets. As dietary barley level increased, DMD and GED decreased linearly (P less than .05), whereas %NRT increased linearly (P less than .10). Apparent N digestibility was not affected by dietary treatment (P greater than .12). Experiments 4 and 5 were 35-d growth trials with treatments arranged in a 2 x 3 factorial design to determine the effects of barley particle size (fine, 635 microns or medium, 768 microns) and dried whey level (0, 10 or 20%) on pig performance. Average daily gain and ADFI increased linearly (P less than .01) as whey level increased. Pigs fed diets containing fine-ground barley grew faster and were more efficient (P less than .05) than those fed medium-ground barley diets.(ABSTRACT TRUNCATED AT 250 WORDS)     

Efficacy of dried whey and its lactalbumin and lactose components at two dietary lysine levels on postweaning pig performance and nitrogen balance.

Two experiments were conducted to determine the efficacy of lactalbumin and lactose components of dried whey on gain and feed performance responses and N retention of weanling swine. In Exp. 1, a 2 x 5 factorial arrangement of treatments in a randomized complete block design in seven replicates was used to evaluate the efficacy of two dietary lysine levels (.90 and 1.30%) in 1) a corn-soybean meal (C-SBM) mixture, 2) C-SBM and 20% dried whey (C-SBM-DW), or the dried whey component replaced with 3 lactalbumin and cornstarch, 4) lactose and an amino acid mixture, or 5) the combination of lactalbumin and lactose. A total of 420 pigs weaned at 23 +/- 2 d of age, weighing an average of 6.87 kg BW, were used in a 3-wk experiment. Experiment 2 was a balance trial conducted as a 3 x 2 x 3 factorial arrangement in a split-plot design in three replicates. The negative (i.e., C-SBM) and positive (i.e., C-SBM-DS) control diets and the C-SBM-lactalbumin-cornstarch diets at the two lysine levels of Exp. 1 were the main plots, each evaluated for a 3-wk postweaning period. Growth rate (P less than .05), feed intake (P less than .01), N retention (P less than .01), and apparent N digestibility (P less than .05) were increased when pigs were fed the C-SBM-DW compared with the C-SBM diet.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of nitrogen and energy source on nutrient digestibility in the young pig

Dried whole whey, lard or dried skim milk was added to a corn-soybean meal basal diet to determine the effect on apparent nitrogen (ND), energy (ED) and dry matter digestibility (DMD) in pigs weaned at 28 d. Four groups of four littermate barrows were allotted to the experimental diets and placed in individual metabolism pens for 12 d (3 d adjustment and three collection periods of 3 d each) after weaning. The study was a 4 X 3 factorial with diet and period as main effects. Addition of dried skim milk or dried whey to the diet resulted in higher values (P less than .05) for DMD and ED as compared with the basal or corn-soy and lard diet. Pigs fed added dried skim milk had improved (P less than .05) ND over pigs on other dietary treatments. All nutrient digestibility coefficients increased (P less than .05) from period 1 to period 2, and ND increased (P less than .05) from period 2 to 3. It was concluded that the young pig requires at least 6 to 9 d after weaning at 28 d to adjust to typical corn-soybean meal starter diets.     

Comparison of wheat or corn dried distillers grains with solubles on rumen fermentation and nutrient digestibility by feedlot heifers

A 5 × 5 Latin square design trial was conducted to evaluate rumen fermentation and apparent nutrient digestibility in 5 rumen-cannulated heifers (420 ± 6 kg) fed a barley-based finishing diet supplemented with 20 or 40% wheat or corn dried distillers grains with solubles (DDGS). The composition of the control diet was 88.7% rolled barley grain, 5.5% supplement, and 5.8% barley silage (DM basis). Increasing the quantity of corn DDGS in the ration resulted in a quadratic decrease in DMI (P = 0.04) and OM intake (P = 0.05). Rumen pH, pH duration, and area under rumen pH thresholds of 5.8 or 5.5 were not affected (P > 0.05) by treatment. Inclusion of wheat DDGS resulted in a quadratic increase (P = 0.05) in pH area below the cutoff value of 5.2, with the most pronounced effect at 20% inclusion. Wheat DDGS linearly increased (P = 0.01) rumen NH(3)-N concentrations. Increasing the inclusion rate of wheat and corn DDGS resulted in quadratic (P = 0.05) and linear (P = 0.04) decreases in rumen propionate, whereas butyrate increased quadratically (P < 0.01) and linearly (P < 0.01), respectively. Feeding wheat DDGS linearly decreased (P < 0.01) DM and OM digestibility values. Inclusion of corn DDGS increased the digestibility values of ether extract (P = 0.05; quadratic response) and CP (P < 0.01; linear response). Neutral detergent fiber digestibility increased in a linear fashion (P = 0.01) as both wheat and corn DDGS inclusion increased, whereas ADF digestibility increased linearly (P = 0.03) for wheat and quadratically (P = 0.02) for corn DDGS. Increased inclusion of wheat DDGS resulted in a linear decrease in GE digestibility (P = 0.01), whereas increasing corn DDGS inclusion linearly increased (P < 0.01) the DE content of the diet. Feeding both wheat and corn DDGS linearly increased (P = 0.01) the excretion of N and P. In summary, replacement of barley grain with up to 40% wheat or corn DDGS did not mitigate rumen pH conditions associated with mild to moderate acidosis in heifers fed a barley-based finishing diet. Supplementing corn DDGS increased nutrient digestibility of all nutrients and, as a result, led to greater DE content. Supplementation of wheat DDGS reduced DM and OM digestibility values, with no effect on DE content. Increased N and P excretion by heifers fed DDGS at 20 or 40% of dietary DM presents a challenge for cattle feeders with respect to nutrient management.     

Effects of feeding dried broccoli floret residues on performance,ileal and total digestive tract nutrient digestibility,and selected microbial populations in broiler chickens

A study was conducted to determine the effects of feeding dried broccoli floret residues on growth performance, apparent ileal digestibility (AID) and apparent total tract nutrient digestibility (ATTD) coefficients, and intestinal microbial populations in broiler chickens. One thousand two hundred day-old male Ross 508 broilers were randomly allotted to 4 dietary treatments and were grown over a 35-d experimental period. Dietary treatments included 4 levels of dried broccoli floret residues: 0, 3, 6, and 9%. Results showed that inclusion of dried broccoli floret residues increased body weight gain (quadratic effect, P = 0.004) and feed conversion ratio (quadratic effect, P = 0.002) with no effect on feed intake. Apparent ileal crude protein (CP, quadratic effect, P = 0.003) and dry matter (DM, quadratic effect, P = 0.002) digestibility for younger birds (25 d of age) increased as the level of dried broccoli floret residues in the diet increased. However, apparent ileal CP (linear effect, P = 0.022), DM (linear effect, P = <0.001) and gross energy (linear effect, P = 0.001) digestibility for older birds (35 d of age) decreased as a result of dried broccoli residue inclusion. Nitrogen (N) corrected apparent metabolizable energy decreased (linear effect, P < 0.001) as the level of dried broccoli floret residues in the diet increased. However, N retention was not influenced by dried broccoli floret residue inclusion. It was concluded that incorporation of dried broccoli floret residues in broiler diet at moderate levels (i.e., 3 to 6%) may improve the growth of broiler chickens with no detrimental effects on nutrient digestibility and retention. However, at high levels (i.e., 9%), dietary dried broccoli floret residues may compromise ileal and total tract nutrient digestibility.     

Effects of dietary dried whey and corn oil on weanling pig performance, fat digestibility and nitrogen utilization

Two experiments were conducted to evaluate the effects and interactions of dietary levels of corn oil (0 vs 6%) and dried whey (0 vs 25%) on performance of young pigs during a 4-wk postweaning period. The first experiment, conducted in five replicates as a 2 x 2 factorial in a randomized block design, evaluated gain and feed intakes of 172 pigs weaned at 21 d of age. Pigs were bled at weekly intervals, and samples were assayed for serum triglyceride and urea concentrations. In a second experiment, 36 barrows in three replicates were used to evaluate the same treatments on apparent digestibility and absorption of fat and N retention during each week of a 4-wk postweaning period. The dietary inclusion of dried whey resulted in greater gains and feed intakes and reduced feed-to-gain ratios during each week of the postweaning period, with the largest relative improvement occurring during wk 1. Supplemental corn oil did not enhance pig gains the first 3 wk postweaning, but response improved by wk 4. Feed intakes were slightly (P less than .10) lower when corn oil was provided. The inclusion of corn oil resulted in an improved feed-to-gain ratio (P less than .01), particularly evident during wk 3 and 4 postweaning. Neither gain nor feed utilization were improved by added corn oil during the initial 2-wk postweaning period regardless of dried whey addition. Apparent digestibilities of fat were unaffected at each weekly interval by dietary dried whey inclusion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of emulsification, fat encapsulation, and pelleting on weanling pig performance and nutrient digestibility

Two experiments were conducted to evaluate the effect of lysolecithin on performance and nutrient digestibility of nursery pigs and to determine the effects of fat encapsulation by spray drying in diets fed in either meal or pelleted form. In Exp. 1, 108 pigs (21 d of age; 5.96 +/- 0.16 kg BW) were allotted to one of four dietary treatments (as-fed basis): 1) control with no added lard, 2) control with 5% added lard, 3) treatment 2 with 0.02% lysolecithin, and 4) treatment 2 with 0.1% lysolecithin in a 35-d experiment. Added lard decreased ADG (P = 0.02) and ADFI (P < 0.06) during d 15 to 35 and overall. Lysolecithin improved ADG linearly (P = 0.04) during d 15 to 35 and overall, but did not affect ADFI or G:F. Addition of lard decreased the digestibility of DM (P = 0.10) and CP (P = 0.05) and increased (P = 0.001) fat digestibility when measured on d 10. Lysolecithin at 0.02%, but not 0.10%, tended to improve the digestibility of fat (P = 0.10). On d 28, digestibilities of DM, fat, CP, P, (P = 0.001), and GE (P = 0.03) were increased with the addition of lard, and lysolecithin supplementation linearly decreased digestibilities of DM (P = 0.003), GE (P = 0.007), CP, and P (P = 0.001). In Exp. 2, 144 pigs (21 d of age, 6.04 +/- 0.16 kg BW) were allotted to one of six treatments in a 3 x 2 factorial randomized complete block design. Factors included 1) level (as-fed basis) and source of fat (control diet with 1% lard; control diet with 5% additional lard; and control diet with 5% additional lard from encapsulated, spray-dried fat) and 2) diet form (pelleted or meal). Addition of lard decreased feed intake during d 0 to 14 (P = 0.04), d 15 to 35 (P = 0.01), and overall (P = 0.008), and improved G:F for d 15 to 35 (P = 0.04) and overall (P = 0.07). Encapsulated, spray-dried lard increased ADG (P = 0.004) and G:F (P = 0.003) during d 15 to 28 compared with the equivalent amount of fat as unprocessed lard. Pelleting increased ADG (P = 0.006) during d 0 to 14, decreased feed intake during d 15 to 35 (P = 0.01), and overall (P = 0.07), and increased G:F during all periods (P < 0.02). Fat digestibility was increased (P = 0.001) with supplementation of lard, and this effect was greater when diets were fed in meal form (interaction, P = 0.004). Pelleting increased the digestibility of DM, OM, and fat (P < 0.002). Results indicate that growth performance may be improved by lysolecithin supplementation to diets with added lard and by encapsulation of lard through spray drying.     

日粮磷水平对空怀期云南半细毛羊养分消化率的影响

为研究日粮磷（P）水平对空怀云南半细毛羊养分消化率的影响，选择25只空怀期云南半细毛羊随机分为5组，分别饲喂5种不同磷水平（0.19%、0.32%、0.45%、0.56%和0.64%）日粮，14 d预饲期后进行消化试验（5 d）。采样期每天采集各组精料200 g，粗料200 g。每只羊的鲜粪样混匀称重后取20%分成两份，一份按5%的比例加入10%的稀盐酸进行固氮。每天采集的饲料样和粪样经55℃风干后回潮24 h，粉碎过40目筛，进行相应指标的测定。结果表明：日粮磷水平对钙（Ca）的表观消化率无影响（P>0.05）。随着日粮磷水平的增加，干物质（DM）和粗蛋白质（CP）表观消化率逐渐降低，且0.19%、0.32%磷水平组极显著高于0.64%磷水平组（P<0.01）；能量（EG）、粗脂肪（EE）、粗灰分（Ash）、中性洗涤纤（NDF）和酸性洗涤纤维（ADF）表观消化率逐渐升高后降低再逐渐升高，拐点出现在0.45%磷水平组。随着日粮磷水平的增加，磷的表观消化率逐渐降低，0.19%磷水平组极显著高于0.45%、0.56%、0.64%磷水平组（P<0.01），其他组间差异不显著（P>0.05）。通过回归分析发现，日粮磷水平与干物质、粗蛋白质、磷的表观消化率之间呈显著的线性关系（R²分别为0.7823、0.8386、0.9976）。综上所述，在本试验条件下，日粮磷水平对空怀期云南半细毛羊钙的表观消化率无影响，随日粮磷水平的增加，干物质、粗蛋白质和磷的表观消化率逐渐降低。当日粮磷水平为0.32%时空怀期云南半细毛羊对主要营养成分的表观消化率最高。     

Effects of individual or combined xylanase and phytase supplementation on energy, amino acid, and phosphorus digestibility and growth performance of grower pigs fed wheat-based diets containing wheat millrun

The objective of these studies was to determine if dietary enzymes increase the digestibility of nutrients bound by nonstarch polysaccharides, such as arabinoxylans, or phytate in wheat millrun. Effects of millrun inclusion rates (20 or 40%), xylanase (0 or 4,375 units/kg of feed), and phytase (0 or 500 phytase units/kg of feed) on nutrient digestibility and growth performance were investigated in a 2 x 2 x 2 factorial arrangement with a wheat control diet (0% millrun). Diets were formulated to contain 3.34 Mcal of DE/kg and 3.0 g of true ileal digestible Lys/Mcal of DE and contained 0.4% chromic oxide. Each of 18 cannulated pigs (36.2 +/- 1.9 kg of BW) was fed 3 diets at 3x maintenance in successive 10-d periods for 6 observations per diet. Feces and ileal digesta were collected for 2 d. Ileal energy digestibility was reduced (P < 0.01) linearly by millrun and increased by xylanase (P < 0.01) and phytase (P < 0.05). Total tract energy digestibility was reduced linearly by millrun (P < 0.01) and increased by xylanase (P < 0.01). For 20% millrun, xylanase plus phytase improved DE content from 3.53 to 3.69 Mcal/kg of DM, a similar content to that of the wheat control diet (3.72 Mcal/kg of DM). Millrun linearly reduced (P < 0.01) ileal digestibility of Lys, Thr, Met, Ile, and Val. Xylanase improved (P < 0.05) ileal digestibility of Ile. Phytase improved ileal digestibility of Lys, Thr, Ile, and Val (P < 0.05). Millrun linearly reduced (P < 0.05) total tract P and Ca digestibility and retention. Phytase (P < 0.01) and xylanase (P < 0.05) improved total tract P digestibility, and phytase and xylanase tended to improve (P < 0.10) P retention. Phytase improved Ca digestibility (P < 0.05) and retention (P < 0.01). The 9 diets were also fed for 35 d to 8 individually housed pigs (36.2 +/- 3.4 kg of BW) per diet. Millrun reduced (P < 0.05) ADFI, ADG, and final BW. Xylanase increased (P < 0.05) G:F; phytase reduced (P < 0.05) ADFI; and xylanase tended to reduce (P = 0.07) ADFI. In summary, millrun reduced energy, AA, P, and Ca digestibility and growth performance compared with the wheat control diet. Xylanase and phytase improved energy, AA, and P digestibility, indicating that nonstarch polysaccharides and phytate limit nutrient digestibility in wheat byproducts. The improvement by xylanase of energy digestibility coincided with improved G:F but did not translate into improved ADG.