The Effects of a Natural Antibiotic Alternative and a Natural Growth Promoter Feed Additive on Broiler Performance and Carcass Quality

The use of subtherapeutic levels of antibiotics in poultry feed improves performance and morbidity in broiler chickens. However, consumer pressure related to the potential development of antibiotic-resistant bacteria has resulted in the development of nonantibiotic feed additives that may also improve broiler performance. Essential oils, organic acids, and phytogenic compounds enhance production of gastric secretions, stimulate blood circulation, and reduce levels of pathogenic bacteria. The objective of the current study was to assess the use of Biostrong 505+ and Biostrong 510 as natural growth promoters in broiler chickens. Assessment was based on the performance and carcass quality of broilers fed either a maximum-yield or a least-cost commercial broiler diet. The maximum-yield diet improved broiler performance and carcass quality. Biostrong 505+ can be used to improve feed conversion and breast yield when incorporated into diets devoid of antibiotics. This improvement in feed conversion and breast yield was accentuated when Biostrong 505+ was used in conjunction with a maximum-yield diet. Biostrong 510 improved feed conversion when used in poultry diets containing antibiotics.     

早期数量限饲对肉仔鸡生长性能和胴体特性的影响

试验研究了早期数量限饲对肉仔鸡生长性能和胴体品质的影响。200只8日龄艾维茵肉仔鸡被随机分成4组,每组五个重复,每重复10只鸡。对照组基础饲粮根据NRC营养水平配制,试验组肉仔鸡从8日龄开始喂料量分别为对照组的90%、80%和70%,限饲1周后各组恢复自由采食。试验结果表明:在第2周,限饲各组肉仔鸡的体重和日增重分别显著低于对照组(P<0.05);在第3周,限饲90%组完成补偿生长,体重与对照组差异不显著(P>0.05);在第4周,限饲80%和70%组完成补偿生长,体重与对照组差异不显著(P>0.05);5、6、7周及2～7周各组在体重、日增重、日采食量和饲料转化率等方面都无显著差异(P>0.05)。早期数量限饲对肉仔鸡胴体特性没有显著影响(P>0.05)。     

Effect of dietary digestible lysine level on growth performance,blood metabolites and meat quality of broilers 23–38 days of age

This study was done to evaluate the effects of different dietary digestible lysine (dig Lys) levels on growth performance, blood metabolites, carcass and breast yield, and breast meat quality of broilers 23–38 days of age. Three hundred 23-day-old Cobb-500 male broiler chickens were allocated to a completely randomized design with five treatments (finisher diet containing 0.88%, 0.94%, 1.00%, 1.06% and 1.12% dig Lys) and six replicates of 10 birds each. Feed intake (FI) was not affected by different dietary dig Lys levels. Weight gain (WG) linearly increased and feed conversion ratio (FCR) linearly decreased with an increasing dietary dig Lys levels. With increasing dietary dig Lys levels, carcass and breast yield and breast meat hue angle (h^*) linearly increased, but abdominal fat decreased quadratically, whereas breast meat lightness (L^*) and ether extract composition linearly decreased. Dietary dig Lys levels did not show any significant effect on serum metabolites, breast meat cooking loss and water holding capacity. Based on the linear broken-line regression models, the weight gain, feed conversion ratio and breast yield were optimized when dietary dig Lys levels were 0.95%, 1.01% and 1.02% respectively. It is concluded that Lys requirements vary according to what productive parameter is taken for optimization. A minimum of 1.02% dig Lys concentration in the finisher diet is suggested to optimize breast yield, feed efficiency and performance in broiler chickens.     

Effects of dietary amino acid density and metabolizable energy level on the growth and meat yield of summer-reared broilers

The effects of dietary amino acid (AA) density and AME on the growth and meat yield of summer-reared Cobb × Cobb 700 (CCB-700) broilers were evaluated. In addition, the responses of CCB-700 and Cobb × Cobb 500 (CCB-500) broilers to dietary AME levels (with low AA) were compared. All chicks were fed through a starter, grower, finisher, and withdrawal phase program. Grow-out performance, carcass traits, meat yield, and feed cost efficiency were evaluated using 2 separate 2-way ANOVA based on 2 separate 2 × 2 factorial arrangements of treatments. Each group includes 14 replicate pens with 14 chicks/replicate. Mortality was not affected by treatment; however, as compared with birds fed other diets, feeding CCB-700 broilers a low-AME and high-AA density diet decreased feed intake and BW on d 35, 42, and 54, and decreased carcass, breast, wing, front half, and back half weights on d 55. The CCB-500 broilers consumed more feed and gained more weight as compared with CCB-700 broilers at 14, 28, and 35 d of age. However, at 55 d of age, breast weight and wing yield were observed to be higher in the CCB-700 than in the CCB-500 broilers. However, the back half (drumstick and thigh) weights were lower in the CCB-700 than in the CCB-500 broilers. In conclusion, without affecting feed costs, broiler performance and carcass yield were affected by diet in both strains. More specifically, a higher AME diet and lower AA density increased the yield of all cut-up parts, except for legs, in summer-reared CCB-700 chicks.     

Genetic parameters for dry matter, energy and protein intake, and their relationships with performance and carcass traits in Japanese Black cattle

Genetic parameters for feed intake and performance traits of 514 bulls and carcass traits of 22 099 of their progeny, and the relationships of measures of feed intake with performance and carcass traits were estimated. Feed intake traits were dry matter intake (DMI), concentrate intake (CONI), roughage intake, ratio of roughage intake to DMI, metabolizable energy intake (MEI) and digestible crude protein intake (DCPI). Performance traits included daily gain, metabolic weight, live weight at the end of test, dry matter conversion ratio and residual feed intake. Progeny carcass traits were carcass weight, percentage of meat yield, rib eye area (REA), subcutaneous fat, marbling score, meat colour (MCS), fat colour (FCS) and meat quality grade. All the feed intake and performance traits were moderately heritable. The heritabilities for REA and MCS were moderate, and that for FCS was low, while those for the other carcass traits were high. Selection against DMI, CONI and DCPI would reduce excessive intake of feed, but would have undesirable effects on growth and most of the carcass traits. Selection against MEI would lead to improvements in feed efficiency and growth traits. Selection against DCPI would also improve feed efficiency; however, responses in growth traits would decrease. Results indicate that selection against MEI might be better than any other measures of feed intake to improve feed efficiency with simultaneous improvement in growth and most of the carcass traits.     

Effect of increasing supplemental phytase concentration in diets fed to Hubbard × Cobb 500 male broilers from 1 to 42 days of age

Phytase supplementation beyond the standard doses used for phosphorus release has been reported to result in extraphosphoric effects by enhancing nutrient digestibility resulting in improved performance of broilers. A study was conducted to examine the effects of the progressive addition of an enhancedEscherichia Coli phytase (400–1,600 phytase units; FTU) on growth performance and carcass characteristics from 1 to 42 d of age in male broilers. One thousand four hundred Hubbard × Cobb 500 1-d-old chicks were randomly distributed into 56 floor pens (0.08 m²/bird). Seven dietary treatments were provided in a 3-phase feeding program consisting of (1) a positive control (adequate Ca and nonphytate P; PC); (2) 1 negative control (Ca and nonphytate P reduced by 0.14% and 0.13%; NC); (3 to 6) the NC diet with 4 increasing supplemental phytase concentrations (NC + 400 FTU, NC + 800 FTU, NC + 1,200 FTU, and NC + 1,600 FTU, respectively); and (7) a low-energy NC diet without phytase and xylanase (reduced 66 kcal of AME_n/kg). Body weight gain, feed conversion, mortality, weight and yield of whole carcass, abdominal fat, and pectoralis major and minor muscles were evaluated. Progressive supplementation of phytase decreased cumulative FCR linearly. Broilers fed diets containing 1,600 FTU had heavier total breast meat by 49 g compared with birds receiving the PC diets. Broilers consuming the NC + 400 FTU or the low-energy NC diet had similar growth performance and meat yield compared with birds provided PC diet. These data indicated that phytase supplementation beyond the need for phosphorus enhances growth performance and carcass characteristics.     

日粮锌水平对4~6周龄肉仔鸡生长性能、胴体性能及肉品质的影响

研究日粮锌水平对4~6周龄肉仔鸡生长性能、胴体性能和肉品质的影响。360只1日龄Arbor Acres(AA)肉公雏,0~3周龄统一饲喂同种日粮(含锌86.25 mg/kg),于22日龄从中选取288只鸡按体重随机分成8个处理,每个处理分6个重复笼饲养,每个重复笼6只鸡。分别饲喂不添加锌的玉米-豆粕型基础日粮(对照组,含锌27.66 mg/kg)和在基础日粮中分别添加20、40、60、80、100、120和140 mg/kg锌(试剂级硫酸锌)日粮。试验期21 d。研究结果表明,日粮锌水平对4~6周龄肉仔鸡生长和胴体性能均无显著影响(P>0.10),但日粮中添加适宜水平的锌可显著降低肉仔鸡胸肌、腿肌的滴水损失和胸肌丙二醛含量,提高胸肌L^*值(P<0.10)。     

Free availability of high‐energy foods led to energy over‐ingestion and protein under‐ingestion in choice‐fed broilers

The objective of this study was to compare energy and protein content of the diet selected by choice‐fed broilers with that of broilers fed a balanced diet. One hundred and eighty 1‐day‐old male broilers were randomly assigned in groups of 10 to one of three experimental treatments (n = 6). Control broilers were fed a standard balanced diet, whereas choice‐fed broilers were fed three foods which were more concentrated (Choice C+ treatment) or less concentrated (Choice C– treatment) in protein, carbohydrate or fat. We evaluated food intake behavior, nutrient intake, and performance parameters of broilers from 2 to 7 weeks of age. Choice C+ broilers showed enhanced preference for the high‐fat food, which led to higher energy intake and lower protein intake than those of control broilers at 2 to 4 weeks of age. Body weight, weight gain and feed conversion efficiency were negatively affected by diet selection of Choice C+ broilers. Choice C– broilers selected a balanced diet, and showed performance parameters similar to those of control broilers. Our results supported the hypothesis that free availability of high‐energy foods bias ingestive behavior of choice‐fed broilers toward selecting a diet with higher energy and lower protein than needed for normal growth.     

日粮硒水平对22~42日龄肉仔鸡生长性能及肉品质的影响

为研究日粮硒水平对22~42日龄肉仔鸡生长性能和肉品质的影响,试验选用380只1日龄Arbor Acres（AA）肉公雏,1~21日龄统一饲喂同种正常添加无机硒的玉米-豆粕型日粮（含硒0.47 mg/kg）,于22日龄从中选取体重接近的336只鸡,随机分成6个处理组,每组7个重复,每个重复8只鸡。分别饲喂不添加硒的玉米-豆粕型基础日粮（对照组,含硒0.015 mg/kg）和在基础日粮中分别添加0.10、0.20、0.30、0.40和0.50 mg/kg硒（以亚硒酸钠形式添加）的试验日粮,试验期21 d。结果表明,日粮中添加不同硒水平对22~42日龄肉仔鸡平均日增重、平均日采食量和料重比均无显著影响（P>0.05）;对42日龄肉仔鸡屠宰率、全净膛率、胸肌率、腿肌率和腹脂率均无显著影响（P>0.05）;日粮中添加不同硒水平对42日龄肉仔鸡腿肌剪切力和胸肌肉色L^*值有显著影响（P<0.05）,其中添加0.50 mg/kg硒处理组肉鸡的腿肌剪切力最低,添加0.20和0.50 mg/kg硒处理组肉鸡的胸肌肉色L^*值最低,但其他肉质性状指标在各组间均无显著差异（P>0.05）。综上所述,玉米-豆粕型基础日粮中添加不同水平硒对22~42日龄肉仔鸡生长性能与42日龄肉仔鸡胴体性状均无显著影响,但日粮中添加0.50 mg/kg硒降低了腿肌剪切力和胸肌L^*值,对肉品质有一定的改善作用。     

Influences of wet feeding and supplementation with ascorbic acid on performance and carcass composition of broiler chicks exposed to a high ambient temperature.

In two experiments was investigated whether feeding with an air-dry feed mixed with different amounts of water and/or supplemental ascorbic acid affect performance and carcass compositions of broilers exposed to a high ambient temperature (35 to 37 degrees C for 8 h/d and thermoneutral for 16 h/d). In the first trial, 64 one-week-old male broiler chicks were fed ad libitum in four dietary treatment groups for a 6-week period. Experimental mash diets were prepared by mixing a maize-soybean based standard broiler starter or finisher with tap water in the ratios of 0.0:1.0, 0.5:1.0, 1.0:1.0 and 1.5:1.0 (water:air-dry feed, w/w). More water in the diet increased BWG, DMI, abdominal fat and carcass weight, carcass CP, crude fat, but it deteriorated DM conversion efficiency. In the second experiment, 64 one-week-old male broiler chicks were given air-dry or wet (water:feed, 1.5:1) starter or finisher diets without or with ascorbic acid supplementation (0 and 250 mg/kg air-dry feed, resp.) ad libitum for a 6-week period. Ascorbic acid supplementation increased BWG, carcass weight and carcass CP significantly, while reducing carcass crude fat content. However, feeding broilers with a diet mixed with water in a ratio of 1.5:1.0 increased BWG, DMI, carcass weight and carcass lipid markedly, but deteriorated DM conversion efficiency. There was also a significant interaction between ascorbic acid and wet feeding, whereby ascorbic acid supplementation induced a significant reduction in carcass lipid contents of broilers fed on air-dry diets but not on wet diets. It is concluded that wet feeding, especially an addition of 150% water to produce a porridge like consistency, improved growth performance by increasing fat, ash and protein deposition in the body, while reducing DM conversion efficiency. It is also concluded that under heat stress supplemental ascorbic acid in air-dry diets stimulates broiler performance but not in wet diets.     

饲粮锌对肉鸡生长性能、组织含锌酶活性以及金属硫蛋白含量的影响

选用720只1日龄商品代AA肉公鸡进行试验,研究饲粮中添加不同水平无机锌对肉仔鸡生长性能、肝脏铜锌超氧化物歧化酶(CuZnSOD)活性和肾脏金属硫蛋白(MT)含量的影响,以考核这些指标对评价肉仔鸡锌营养状况的意义。将肉鸡按平均体重随机分成8个处理组,分别饲喂不添加锌的玉米-豆粕型基础饲粮(对照组,含锌28.37mg/kg)和在对照组基础饲粮中以无机硫酸锌形式分别添加20、40、60、80、100、120mg/kg和140mg/kg锌的试验饲粮21d。结果表明:肉仔鸡的日增重、日采食量和肾脏MT含量均受到添加锌水平的显著影响(P<0.05),其中肾脏MT含量受锌水平影响极显著(P<0.01),而不同锌水平对肝脏CuZnSOD活性无显著影响(P>0.1)。这表明对于肉仔鸡,肾脏MT可能是评价机体锌营养状况的敏感指标。     

Cassava starch factory residues in the diet of slow-growing broilers

The objective of this study was to evaluate the effect of inclusion of dehydrated cassava starch residue (DCSR) on the performance, gastrointestinal tract characteristics and carcass traits of ISA Label JA57 slow-growing broilers. A total of 510 broilers at 21 were distributed in a randomized experimental design with 5 treatments (2, 4, 6, 8, and 10 % DCSR inclusion) and a control group, 5 replicates, and 17 birds per experimental unit. The DCSR inclusion from 21 to 49 days of age negatively influenced (P?P?>?0.05) feed conversion in the broilers with increasing of DCSR inclusion. From 21 to 79 days, DCSR inclusion impaired (P?P?P?P?>?0.05) the other parameters of carcass quality and yield, cuts, and percentage of abdominal fat. In conclusion, DCSR inclusion levels above 2 % compromised broiler performance.     

不同锰源与锰水平对肉仔鸡生产性能和组织矿物元素沉积的影响

为研究不同锰源与锰水平对肉仔鸡的生产性能与组织矿物元素沉积的影响,试验采用2×5完全随机试验设计,在玉米—豆粕型基础日粮(锰含量为37.66mg/kg)中添加0、45、90、130、180mg/kg(5个锰添加水平)的复合氨基酸锰和硫酸锰(2种锰源),构成10个日粮处理组,将540只1日龄健康艾维茵肉仔鸡随机分为10个处理组,开展肉仔鸡饲养试验(共42d)。于35日龄时测定其生产性能指标,计算料肉比;于42日龄时测定其胫骨、肝脏、肾脏组织中铜、铁、锌浓度以及胫骨灰分、钙及磷含量。结果表明,在上述日粮中,锰添加量在45~130mg/kg时,无论是添加复合氨基酸锰组还是添加硫酸锰组35日龄肉仔鸡体重和采食量较未添加组差异显著(P≤0.05),经分析,锰水平对其平均体重及采食量有极显著影响(P<0.01);不同锰源的35日龄肉仔鸡体重、采食量、料肉比差异不显著(P >0.05)。42日龄肉仔鸡胫骨、肝脏、肾脏组织中铜、锌、铁含量及胫骨灰分、钙磷含量未受锰源和锰水平及两者互作的显著影响(P >0.05)。由以上结果可以得出,锰水平对肉仔鸡生长性能有极显著影响(P<0.01);锰源对肉仔鸡生产性能无显著影响(P >0.05);锰源和锰水平及两者互作对肉仔鸡组织矿物元素沉积无显著影响(P >0.05)。     

生长早期不同能量、蛋白限饲水平对肉仔鸡补偿生长的影响

本试验研究肉仔鸡生长早期 (2～ 3周龄 )不同代谢能、蛋白质限饲水平对生产性能和胴体品质影响。结果表明 :(1 )早期低代谢能和低蛋白的限饲处理均可明显降低肉仔鸡生长速度 (P <0 .0 5) ,并在恢复阶段表现出完全补偿生长。 (2 )早期不同代谢能、蛋白限饲水平对饲料转化率没有影响 (P >0 .0 5)。 (3)早期不同代谢能、蛋白限饲水平均有提高胴体产量、胸肉和腿肉比例的趋势 (P >0 .0 5)。 (4)早期低代谢能限饲明显降低 42日龄腹脂重 (P <0 .0 5) ,低蛋白质限饲增加腹脂重 (P >0 .0 5)。     

Replacing corn with pearl millet (raw and sprouted) with and without enzyme in chickens' diet

An experiment was conducted to compare a commercial corn–soya bean meal diet with a pearl millet (raw and sprouted) diet containing less soya bean meal, alone or in combination with exogenous enzyme, on growth performance and ileal villus development of chicks. Two‐hundred‐and‐forty‐one‐day‐old male broilers (10/pen) were randomly allocated to one of the following dietary treatments: (i) a standard corn–soya bean meal control diet (CTL); (ii) a raw pearl millet‐soya bean meal diet (PM); (iii) a sprouted pearl millet‐soya bean meal diet (SPM); (iv) CTL + exogenous enzymes (CE); (v) PM + exogenous enzymes (PE); and (vi) SPM + exogenous enzymes (SPE) with four replicate pens/treatment. Body weight of birds at day 21 did not differ between those fed the CTL, and SPM and PE diets. In comparison with feeding broilers the CTL diet, feeding the PE and SPM diets caused significant decrease in feed intake, but with equivalent growth and feed efficiency. However, at day 21, feed conversion ratio did not differ between birds fed the CTL diet and those fed the PM, PE and SPM diets. At day 21, broilers fed the PM and PE diets had longer villi (p < 0.05) than those fed the CTL diet. At day 21, villi width was reduced (p < 0.05) by raw pearl millet supplementation than CTL diet. It is concluded that, in comparison with corn, broiler diets formulated with sprouted pearl millet or pearl millet with enzyme require less soya bean meal and can be used to improve growth performance traits and villus development.     

Effects of dietary level of lysine and of level and source of protein on feed intake, growth performance, and plasma amino acid pattern in the finishing pig.

The effects of dietary level of lysine and of level and source of CP on voluntary feed intake, growth performance, plasma free amino acids, and carcass characteristics were investigated in a study involving 60 female and 60 castrated male Large White finishing pigs (from 42 to 101 kg live weight) with ad libitum access to feed. Six treatments were compared according to a 2 x 3 factorial plan, with two levels of lysine (.55 and .65% selected below the recommended levels for both sexes) and three types of CP (N x 6.25) supply: a 13% CP diet based on wheat, peanut meal and soybean meal; a 15.6% CP diet providing the same amino acid pattern as that of the basal diet; and a 15.2% CP diet containing the same levels of essential amino acids as the 13% CP diet, with the addition of glutamic acid as a source of nonessential amino acids. By maintaining a constant amino acid pattern separate changes in dietary lysine and CP levels resulted in a relative independency of their effects on feed intake, growth performance, and body composition. Muscle gain increased with supplementary lysine, with a lower response at the lower CP level (13%). At the same level of lysine (.55 or .65%), increasing protein content from 13 to 15.6% did not affect feed intake, but growth rate was lower and feed/gain was increased, partly because of an additional energy cost resulting from catabolism of excess protein.(ABSTRACT TRUNCATED AT 250 WORDS)     

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

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

Effects of replacing pharmacological levels of dietary zinc oxide with lower dietary levels of various organic zinc sources for weanling pigs

Two 28-d randomized complete block design experiments were conducted to evaluate the effects of concentrations and sources of Zn on growth performance of nursery pigs. Seven stations participated in Exp. 1, which evaluated the efficacy of replacing 2,500 ppm of Zn from ZnO with 125, 250, or 500 ppm of Zn from Zn methionine. A control diet with 125 ppm of supplemental Zn was included at all stations. A total of 615 pigs were used in 26 replicates. Average weaning age was 20.6 d and the average initial BW was 6.3 kg. There were no differences in any growth response among the three supplemental Zn methionine levels fed in Exp. 1. Zinc supplementation from Zn methionine improved ADG compared with the control during all phases (P < 0.05), due primarily to an increase in ADFI. Pigs fed 2,500 ppm of Zn from ZnO gained faster (P < 0.01) than those fed the control diet during all phases, and faster (P < 0.05) than those fed supplemental Zn from Zn methionine for the 28-d experiment. Differences in gain were again due mainly to differences in feed intake. A second experiment compared five sources of supplemental organic Zn (500 ppm of Zn) with 500 and 2,000 ppm supplemental Zn from ZnO and a control (140 ppm total Zn). Six stations used a total of 624 pigs, with an average weaning age of 20.4 d and averaging 6.2 kg BW in 15 replicates. Pigs fed 2,000 ppm of Zn from ZnO gained faster (P < 0.05) than pigs fed the control or any of the 500 ppm of Zn treatments (ZnO or organic Zn). Pigs fed the 2,000 ppm of Zn from ZnO also consumed more feed than those receiving 500 ppm of Zn from ZnO or from any of the organic Zn sources (P < 0.05). Organic sources of Zn did not improve gain, feed intake, or feed efficiency beyond that achieved with the control diet. Supplemental Zn at a concentration of 500 ppm, whether in the form of the oxide or in an organic form, was not as efficacious for improved ADG as 2,000 to 2,500 ppm of Zn from ZnO.     

日粮磷水平对22~42日龄肉仔鸡胴体性能及肌肉品质的影响

为研究日粮磷水平对22~42日龄肉仔鸡胴体性能和肉品质的影响,选用500只1日龄爱拔益加肉鸡公雏,于1~21日龄统一饲喂相同的玉米—豆粕型配合日粮(含非植酸磷实测值为0.39%),于22日龄从中选取360只鸡,按体重相近原则随机分成10个处理组,每个处理组6个重复笼,每个重复笼6只鸡,分别饲喂不添加无机磷的玉米—豆粕型日粮(对照组,含非植酸磷0.09%)及在基础日粮中分别添加0.05%、0.10%、0.15%、0.20%、0.25%、0.30%、0.35%、0.40%和0.45%无机磷(饲料级CaHPO₄),饲养21 d。结果表明,日粮添加适宜水平的无机磷可显著提高42日龄肉仔鸡屠宰率和全净膛率(P<0.1),但日粮磷水平对42日龄肉仔鸡肉品质各指标及其他胴体性能指标均无显著影响(P>0.1)。     

Lysine requirements of Korean native ducklings for three weeks after hatch

Dietary lysine content in poultry diets is critical to improve feed utilization efficiency, body protein deposition rate, and carcass traits of growing and finishing poultry. The objective of the current study was to estimate the optimum digestible lysine requirements for maximum growth performance, efficient utilization of nitrogen, and carcass traits of male Korean native ducklings for 3 wk after hatch. A total of 720 one-day-old male Korean native ducklings were used in a completely randomized design having 8 dietary treatments to provide a range of digestible lysine content from 0.44 to 1.07%. Ducklings were randomly allotted to 24 floor pens (6 replicates per treatment and 15 ducklings per pen) and were offered the respective diets on an ad libitum basis for the period of study. Body weight and feed intake were measured weekly to calculate feed conversion ratio. At the termination of the experiment, 2 ducklings per pen were euthanized via cervical dislocation to weigh empty body and drumsticks. The digestible lysine requirement was determined by taking a mean value after fitting the data to both linear-plateau and quadratic-plateau models. Digestible lysine requirements for Korean native ducklings for 3 wk after hatch were estimated to be 0.71, 0.74, 0.65 and 1.01% for maximum body weight, daily gain, and daily feed intake, and for minimum feed conversion ratio, respectively.