Effects of a high-protein, low-energy diet in finishing lambs: 1. Feed intake, estimated nutrient uptake, and levels of plasma metabolites and metabolic hormones

Patterns of tissue mobilisation in ruminants are ill-understood. This hinders nutritional management to mitigate the effects of energy deprivation on protein mass, and nutritional regimens designed to change body composition. An experiment was conducted to comprehensively evaluate the effects of a low-energy high-protein diet in growing lambs. Three diets (CON = concentrate diet ad libitum, STR = straw ad libitum, SFM = straw ad libitum plus 150 g/d fish meal) were fed to growing white-face lambs. Analysis of feed intake and metabolite data provided evidence that greater available N did not have a synergistic effect on intake of low quality forage. Metabolite and hormone profiles of lambs in negative energy balance, supplemented with duodenally available protein, revealed that SFM animals did not respond with an accelerated rate of fat mobilization or maintain protein mass due to available N. This was particularly evident from the leptin profiles, which indicated higher circulating leptin levels for SFM compared to STR animals. Further, the data revealed that in sheep fed below requirements for maintenance, leptin levels did not correspond with acute ME intake, whereas the opposite was true for well-fed animals. Conversely, the response of the GH/IGF-1 axis to high protein–energy ratio (PER) diets was indicative of effects not explained by the difference in energy provided by the two experimental diets.

These results contrast with observations from intra-gastric infusion experiments testing similar PERs and previous conventional feeding trials and provide evidence of: (1) specific differences associated with PER in lambs fed via intra-gastric infusion vs. a conventional feeding approach, and (2) lack of usefulness of high PER diets in the post hoc modification of body composition of growing lambs. While positive N balance is known to occur in ruminants in negative energy balance, the determinants of relative proportions of muscle and adipose tissue catabolised under energy deprivation remain unknown.     

低蛋白质日粮对育肥绵羊生长性能、胴体性状及肌肉脂肪酸组成的影响

本研究旨在研究降低全混合日粮蛋白质水平对育肥期绵羊生长性能、胴体性状及肌肉脂肪酸组成的影响.试验将32只平均体重为(38.14±0.45)kg的育肥期绵羊随机分为2组,每组8个重复,每个重复2头.两组绵羊在为期10周的试验期中分别饲喂蛋白质水平为13.5％和8.5％的全混合日粮.结果:将全混合日粮蛋白质水平从13.5％...     

Growth performance,carcass traits,physiochemical characteristics and intramuscular fatty acid composition of finishing Japanese black steers fed soybean curd residue and soy sauce cake

This study was conducted to determine the effects of dietary soybean curd residue (SCR) and soy sauce cake (SSC) on the growth performance, carcass traits and physiochemical and intramuscular fatty acid (FA) characteristics in Japanese Black steers. Ten steers (29.7 ± 0.3 months old, 856.6 ± 24.4 kg body weight) were assigned to either treatment C, fed a conventional concentrate or T, fed the test diet including dried SCR and SSC for 3 months. In growth performance, dry matter (DM) intake and average daily gain, and carcass traits did not differ significantly between the treatments. Color of beef was affected by the dietary treatments and meat samples from T showed higher a^* value and chroma than those in C. On FA composition, there was no significant difference between the treatments in neutral lipids, whereas in polar lipids, meat samples from T had higher C16:1 (P < 0.05) and tended to have higher C16:0 (P = 0.05) and C18:1 (P = 0.08), but lower C17:0 (P = 0.098), C18:2 (P = 0.06) and C20:4 (P = 0.07) than those from C. The study suggested that SCR and SSC could be used as a substitute for conventional concentrate and would influence meat color and intramuscular FA composition of polar lipids.     

青贮艾草对肉牛生长性能、胴体品质及肌肉脂肪酸组成的影响

文章旨在研究育肥期肉牛日粮中添加不同水平的青贮艾草对生长性能、胴体品质及肌肉脂肪酸组成的影响。试验选择15月龄平均体重为(326±22)kg的肉牛24头,随机分为4组,每组6个重复,每个重复1头牛。试验分为育肥前期和育肥后期两个阶段,对照组饲喂基础日粮+水稻秸秆,试验组在基础日粮中分别补充5%、10%和15%的青贮艾草,两个阶段精料补充料干物质、粗蛋白质、粗脂肪、中性洗涤纤维、酸性洗涤纤维、脂肪酸组成及主要脂肪酸含量相近。结果 :精料摄入量随日粮青贮艾草添加水平的升高表现为显著二次曲线效应(P <0.05);随着日粮艾草添加水平的升高,肉牛末重和平均日增重表现为显著二次曲线效应(P <0.05),而料比线性降低(P <0.05)。牛的屠体重、眼肌面积和大理石纹评分随日粮青贮艾草添加水平的升高表现为显著二次曲线效应(P <0.05),而背膘厚度表现为显著二次曲线降低(P <0.05)。眼肌C18:0、C18:1和单不饱和脂肪酸含量显著线性降低(P <0.05),亚麻油酸、C18:3、C20:4、C22:0和C24:1脂肪酸含量显著线性降低(P <0.05),多不饱和脂肪酸和多不饱和脂肪酸与饱和脂肪酸比值表现为显著二次曲线增加(P <0.05)。结论 :日粮青贮艾草添加水平对肉牛生长性能、肌肉脂肪酸含量的影响表现为二次曲线效应,但高水平青贮艾草降低了肉牛生长性能、屠宰性能及肉品质。肉牛育肥期日粮中适宜的青贮艾草添加水平为10%。     

虾蛋白粉对鲈鱼生长性能、机体成分及肝脏脂肪酸组成的影响

文章旨在评估日粮添加不同水平虾蛋白粉对鲈鱼生长性能、机体成分及肝脏脂肪酸组成的影响.试验将456条初始体重为(22.11±0.25)g的鲈鱼随机分为3组,每组4个重复,每个重复38条.对照组饲喂基础日粮,处理组分别为基础日粮+5％和10％虾蛋白粉,试验为期12周.结果:5％和10％虾蛋白粉组鲈鱼的末重、增重、特定生长率...