แบบ b s t r c t4,800 หนึ่งวัน (d) เก่า 500 คดเพศออกทั้งหมดถูกใช้ในการศึกษามีวัตถุประสงค์ของการประเมินโปรแกรมอาหารที่สูตร มีองศาที่แตกต่างกันของข้อจำกัดของโปรตีนหยาบ(CP) และแห้งเสริม L isoleucine และ L-วาลีน โปรแกรมอาหารสี่ (PRG)กลยุทธ์ต่าง ๆ สะท้อนให้เห็นถึงการส่งกรดอะมิโน (AA) การออกใช้ ตามลำดับจาก d 1-7, 8-21, 22-35 และ 36 ถึง 42 ดังต่อไปนี้: PRG 1, CP จำกัด 224, 211198 และ 184 g/kg กับ AA digestible ต่ำไปแอล-ไลซีน (Lys) อัตราส่วนที่กำหนดเฉพาะ สำหรับกำมะถันรวมเอเอ (TSAA) (0.72) และทรีโอนีน (Thr) (0.65); PRG 2, PRG 1 โดยไม่จำกัด CP ด้วยอัตราส่วนเอเอไป Lys ขยายวาลีน (Val) (0.77) และ isoleucine (เมา) (0.67); PRG 3, PRG 2เสริม ด้วยค่า L และ PRG 4 เป็น PRG 3 เสริม ด้วย L-เมา ระยะของการPRG 4 ให้ 1 21 d ได้แบ่ง PRG ลำดับที่ 4 รับจากd 22-42 สำหรับผลรวมของการรักษา 16 การวิจัยเป็น randomized สมบูรณ์ออกแบบบล็อกกับบล็อกครั้งที่ 2 และระยะ 24 ต่อรักษาต่อบล็อก 1 กับ 21 dระยะ 12 จาก 22 ไป 42 และสวรรคตโดยรวม มีไม่มีผลในช่วงเวลาหรือโต้ตอบระหว่าง PRG เลี้ยง 1 21 และ 22-42 d อายุการ ประสิทธิภาพการทำงานและประมวลผลข้อมูลแสดงประโยชน์ของอาหารโดยใช้อัตราส่วนต่ำสุดของค่าและเมา formulating ร่างกายน้ำหนักได้สูงเมื่อมีทั้งเอเอเสริมกัน (PRG 4) อื่น ๆมือ อาหาร (FCR) อัตราการแปลงดีขึ้นเมื่อได้อัตราค่าและเมากับ Lysได้โดยไม่ต้องใช้แหล่งสังเคราะห์ ข้อมูลผลผลิตซากไม่ได้รับผลกระทบ โดย PRGยกเว้นสัดส่วนของไขมันหน้าท้องที่ถูกลดลง (P < 0.05) เมื่อออกได้รับอาหารที่ มีอัตราส่วนต่ำสุดของค่าและเมาโดยแหล่งสังเคราะห์ในสรุป กำหนดอาหารสำหรับไก่เนื้อโดย CP ระดับต่ำสุดแต่ใช้ AA ไปอัตราส่วน Lys ใน PRG 2, 3 และ 4 อนุญาตแข่งขันเติบและผลผลิตของซากผลลัพธ์ที่ ใช้ค่า L และ L-เมานำไปปรับปรุง FCR และ ดังนั้น นี้ความเป็นไปได้ควรอุดมการรักษาประสิทธิภาพการผลิตไก่เนื้อเนื้อ 1. IntroductionBroiler feeds are usually formulated using linear least cost software and frequently set at a minimum concentration ofcrude protein (CP) in a conservative strategy to have indispensable and dispensable amino acid (AA) intakes safeguarded.Providing AA using commercial available synthetic sources [L-Lysine (L-Lys), DL-Methionine (DL-Met) and L-Threonine (L-Thr) as well as Methionine analogue] allowed nutritionists to achieve competitive broiler field performance and meat yields(Hill and Kim, 2013; Kobayashi et al., 2013). Formulating diets with a reduction in CP level is possible with the utilization ofother AA if commercially available at competitive prices. Examples are L-valine (L-Val), the fourth limiting AA for broilersin maize-soybean diets, and L-isoleucine (L-Ile), in many situations the fifth limiting AA, followed by arginine (Corzo et al.,2007, 2010; Berres et al., 2010b; Tavernari et al., 2013). The ideal protein concept has become a worldwide used strategyto formulate broiler feeds. This approach targets to reduce the amount of absorbed AA that are in relative excess to lysine(Lys), thus avoiding excess oxidation, decreasing metabolic costs and improving AA balance (Lemme, 2003; Vieira and Angel,2012).Protein is a costly nutrient in commercial poultry diets. The increasing cost of feed ingredients and the competition withthe biofuel industry for some plant feedstuffs, such as maize and soy oil, indicates a scenario of increased costs for feedingredients in the coming years. Starting in 2007, the prices of the major crops used in animal production have increaseddramatically in real terms reaching a peak in 2008 and then declining in 2009 and 2010, followed by sharp increases againin 2011 (Rosegrant et al., 2012). Therefore, reducing CP through the increased use of synthetic AA can help to maintaincompetitive meat production while minimizing the impact of the increased cost and volatility of protein sources.Commercial implementation of L-Val and L-Ile in poultry feeds is limited because of insufficient information on the effectsof these synthetic AA supplements in feeding programs through the broilers life. Therefore, generating data on live broilerperformance and proportions of meat cuts using diets with or without synthetic L-Val and L-Ile is necessary if nutritionistsare to use them effectively in feed formulation. I the literature there are suggestions of ratios of digestible (dig.) valine (Val)and isoleucine (Ile) to dig. Lys that optimize growth in a range between 0.75 to 0.77 and 0.65 to 0.67, respectively (Corzo et al.,2009, 2010; Berres et al., 2010a,b; Corrent and Bartelt, 2011; Tavernari et al., 2013). However, the optimal ratios betweenthese AA for carcass optimization have not been clearly defined.The objective of the present study was to evaluate the effects of feeding programs using least cost linear formulation,restricting CP or not, and supplementing L-Val and L-Ile, on growth performance, processing yield and proportion of primalcommercial cuts. Effects of feeding the different diets were also investigated when they were provided separately in theperiods of 1 to 21 and 22 to 42 d of age.2. Material and methodsAll procedures used in this study were approved by the Ethics and Research Committee of the Universidade Federal doRio Grande do Sul, Porto Alegre, Brazil.2.1. General bird husbandryTwenty-five day-old male Cobb × Cobb 500 slow feathering broiler chickens were placed in 1.65 m × 1.65 m floor pens(9.2 birds per m2) with rice hulls as bedding. Each pen was equipped with one tube feeder and one bell drinker. Averagetemperature was 32◦C at placement, which was reduced by 1◦C every 2 d to provide comfort throughout the study usingthermostatically controlled heaters, fans and foggers. Lighting was continuous until 7 d of age, with a 14L:10D cycle usedafterwards. Birds had ad libitum access to water and mash feeds.2.2. Dietary treatmentsThe experimental feeds composition and calculated analysis by period are presented in Tables 1–4. Least cost linearprogram was used to formulate diets based on previously analyzed maize and soybean meal (SBM) for AA (method L257;Official Journal of the European Community, 1998). Feeds were formulated using digestible AA coefficient values for the AAof Rostagno et al. (2011).Four feeding phases were used: pre-starter (1–7 d), starter (8–21 d), grower (22–35 d), and finisher (36–42 d). Theminimum ratios of digestible AA to Lys of the diets were 0.72 total sulfur amino acids (TSAA), 0.65 threonine (Thr), 1.08arginine (Arg), 0.17 tryptophan (Trp) and 1.07 leucine (Leu). Experimental diets met or exceeded the recommendations ofRostagno et al. (2011) for all nutrients except CP and AA. Supplementation of AA was carried out using synthetic DL-Met(990 g/kg), L-Lys HCl (780 g/kg), L-Thr (985 g/kg), L-Val (965 g/kg) and L-Ile (985 g/kg). The experimental treatments werebased on different feeding programs (PRG) that resulted from the use of four CP and AA restriction strategies. In PRG 1, CP wasrestricted to 224, 211, 198 and 184 g/kg in the pre-starter, starter, grower, and finisher phases, respectively. The minimumsAA to Lys ratios, however, were set only for TSAA and Thr. In PRG 2, CP was not restricted while the minimum ratios of AAto Lys were extended to include Val (0.77) and Ile (0.67). In PRG 3, feed formulation was as for PRG 2 but with L-Val (0.67,0.55, 0.45, and 0.37 g/kg supplementation, in the pre-starter, starter, grower and finisher phases diets, respectively). In PRG4, feed formulation was as in PRG 3 but both with L-Val and L-Ile (1.15 and 0.48, 0.96 and 0.42, 0.82 and 0.37, and 0.69 and0.33 g/kg supplementation in the pre-starter, starter, grower, and finisher phases, respectively). Since concentrations of themain electrolytes varied as SBM changed in diets with different CP, the dietary electrolyte balance (DEB = total Na + K − ClmEq/kg) was used a restricted nutrient in the feed formulations (Mongin, 1981).Birds were placed in 192 floor pens of 2.8 m2in the number of 25 in each. Two time blocks were used in the presentstudy. Consequently, the 4 PRG were replicated 24 times per block from 1 to 21 d of age (pre-starter and starter phases).From day 22 to the end of the study, the 24 replicates were equally divided into 6 others, which were fed from 22 to 42 d ofage (grower and finisher phases) to one of the 4 previous PRG. Therefore, from 22 to 42 d, there were 16 treatments, eachof them with 6 replicates per block. The final design had 2 time blocks and 48 replicates per treatment from 1 to 21 d of ageand 12 replicates from 22 to 42 d of age.2.3. MeasurementsLive performance was evaluated using the pen broiler weight and feed intake (FI) at 7, 21, 35 and 42 d of age. Pens werechecked daily for any mortality. Feed conversion ratio (FCR) was corrected for the weight of dead birds. At 42 d of age, thebirds were fasted for 8 h and 6 birds per pen were randomly taken from each pen, weighed individually, electrically stunnedwith 45 V for 3 s, bled for 3 min through a jugular vein cut, followed by scalding at 60◦C for 45 s and plucked. Eviscerationas well the rest of processing was manually done by trained industry personnel. Carcasses were chilled in ice for 3 h, hungfor 3 min to draw off excess water and weighed and the abdominal fat was removed and weighed. Carcass cuts, includingdeboned breast meat (Pectoralis major plus Pectoralis minor) with skin, as well as bone-in thighs, drumsticks, wings andcages were also weighed. Carcass yield was expressed relative to live weight, whereas abdominal fat and carcass cuts wereexpressed as a proportion of carcass weight.2.4. Statistical analysesThe study was conducted as a completely randomized block design with time as block. There were 4 PRG with 48rep
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