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通过氮平衡试验和饲养试验,研究日粮不同蛋白水平(18.2%、16.5%、15.5%、14.5%和13.6%)对生长猪生产性能和氮平衡的影响。结果表明,粪氮、尿氮、总氮、氮吸收和氮沉积均随日粮蛋白水平的降低而降低(P<0.05);日粮蛋白水平显著影响了猪的生产性能、眼肌面积、血清尿素氮和血浆游离必需氨基酸浓度(P<0.05);在低蛋白日粮中添加赖氨酸、蛋氨酸和苏氨酸,可使生长猪日粮蛋白水平从18.2%降至14.5%,且大幅度降低氮排泄量而不影响其生产性能;当日粮蛋白水平降低4个百分点以上时,赖氨酸、蛋氨酸和苏氨酸均能够满足生长猪生长需要,但异亮氨酸、缬氨酸和精氨酸等必需氨基酸及酪氨酸和丝氨酸等非必需氨基酸则不能满足其生长需要。  相似文献   
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We studied the influence of pen uniformity at weaning (7.5 ± 0.6 kg vs. 7.5 ± 1.2 kg body weight (BW ± SD)) and sex on growth performance during the nursery (7.5 to 27.3 kg BW) and the fattening (27.1 to 130.5 kg BW) phases and carcass quality of barrows and castrated females (CF). During the nursery phase, pigs from the more uniform pens had lower feed efficiency (P = 0.05) than pigs from the less uniform pens. Also, barrows had higher average daily feed intake (ADFI) (P < 0.05) and average daily gain (P < 0.001) and better feed efficiency (P < 0.001) than CF. During the fattening phase, initial pen uniformity did not affect growth performance of the pigs but barrows tended (P = 0.08) to have higher ADFI and worse feed efficiency than CF. Trimmed primal cut yield tended to be higher for the more uniform pigs and better for barrows than for CF (P = 0.09). It is concluded that regrouping of the pigs at weaning according to uniformity of BW did not affect growth performance or carcass quality of the pigs at slaughter. Castrated females might be used as an alternative to barrows for the production of carcasses destined to the dry‐cured industry.  相似文献   
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研究去势公猪体内脱氢表雄酮(DHEA)及其硫酸盐(DHEA-S)随日龄增长的变化规律,以及外源添加DHEA对去势公猪DHEA与DHEA-S水平、血脂以及脂肪沉积的影响,通过测定杜×(长×大)三元杂交仔公猪、仔母猪(21日龄)及去势公猪(28~203日龄)血清DHEA、DHEA-S、血糖、总胆固醇和甘油三酯的生理水平。选用体重40 kg左右的杜×(长×大)三元杂交去势公猪45头,随机分成3组,分别在对照组、低剂量组和高剂量组的饲料中添加0、25和75 mg/kg DHEA,处理105 d。结果显示:21日龄仔公猪血清DHEA质量浓度为仔母猪的2.86倍,明显高于仔母猪(P<0.001);28~203日龄去势公猪血清DHEA质量浓度仅为21日龄仔公猪的5.37%~12.03%,皆明显降低(P<0.001),且呈U型变化;日粮中添加DHEA明显增加去势公猪血清DHEA浓度,显著降低血清胆固醇、甘油三酯浓度和脂肪沉积,而对体重及血清DHEA-S浓度影响不显著。猪血清DHEA生理水平变化以及添加DHEA对脂质代谢指标的影响,提示DHEA具有调节去势公猪脂质代谢的作用。  相似文献   
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Seventy-five individually fed barrows averaging 35 kg were used in a series of three experiments for 6-week growth assays (25 barrows each) to determine the effects of l -tryptophan (Trp) supplementation on growth performance and to establish the lower limits of dietary crude protein (CP) levels. Corn and soybean meal (SBM)-based diets containing 9% (Experiment 1), 10% (Experiment 2), and 11% CP (Experiment 3) fortified with deficient essential amino acids (AAs) except Trp were used as basal diets for each experiment. The experimental diets were supplemented with 0.00%, 0.02%, 0.04%, or 0.06% Trp. A 16% CP corn–SBM-based diet was set as a positive control in each experiment, and feed and water were provided ad libitum. Average daily gain and gain-to-feed ratio improved quadratically (P < 0.05) as supplemented Trp increased in the 9% and 10% CP group, although these positive effects were not observed in the 11% CP group. Because the maximum performance parameters in 9%, 10%, and 11% CP groups were not different from that of the 16% CP positive control group, the marginally reduced level of dietary CP without growth performance being affected appears to be around 9% at most. A potential reduction of nitrogen intake was clearly indicated.  相似文献   
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