Effects of limited concentrate feeding on growth and blood and serum variables, and on nutrient digestibility and gene expression of hepatic gluconeogenic enzymes in dairy calves

This study elucidated the effects of limited concentrate feeding on growth, nutrient digestibility, blood profile and gene expression of gluconeogenic enzymes in the liver of dairy calves. The study utilized 36 German Holstein dairy calves (5-7 days of age) divided into two groups of 18 calves each for 150 days. Control group calves received 2 kg/(calf × day) of concentrate, whereas calves in the restricted group received only 1 kg/(calf × day). Good quality forage (mixture of maize and grass silages) was available for ad libitum consumption to both groups. The intake of milk replacer before weaning, and of concentrate were recorded daily per calf; however, the consumption of forages was quantified as daily average of the group. Body weights (BW) were recorded at start and on days 35, 70, 112 and 150. Blood and serum samples and spot urinary and faecal samples were also collected at similar time points. On days 70 and 150, liver biopsies were collected from seven animals in each group. The BW was not different between the groups at all times. Total BW gain in the control group was 124 kg as opposed to 111 kg in restricted group that led to average BW gain of 827 g/day and 739 g/day in respective groups, and the differences were significant (p = 0.018). As planned, the control group had higher concentrate and lower forage intake than the restricted group. The blood haemoglobin, haematocrit and serum variables (glucose, total protein, albumin and urea) were within the normal range in both groups, but serum glucose was higher (p < 0.05) in control than in restricted group at 70 days. There was no difference between groups in organic matter (OM) digestibility which declined (p < 0.001) with increasing age in both groups. Microbial crude protein (MCP) synthesis estimated from urinary allantoin excretion increased (p < 0.001) in both groups with increasing age but was not different between groups. The mRNA expressions for the gluconeogenic enzymes, cytosolic and mitochondrial phosphoenol pyruvate carboxykinase (EC 4.1.1.32) and pyruvate carboxylase (EC 6.4.1.1) measured by quantitative real-time PCR in liver biopsies showed no differences between groups. Overall, restricting concentrate moderately reduced the growth intensity without affecting the normal serum and blood indices, and MCP synthesis and OM digestibility showed no differences between groups, indicating that both concentrate feeding schemes can be successfully applied.     

Effect of Fusarium toxin-contaminated triticale and forage-to-concentrate ratio on fermentation and microbial protein synthesis in the rumen

In this study, the effect of Fusarium toxin-contaminated triticale (FUS) at high (60%) and low (30%) concentrate proportion in ruminant rations on ruminal fermentation, microbial protein synthesis and digestibility was investigated, using in vivo and in vitro methods. Significant effects of the forage-to-concentrate ratio on ruminal degradation and digestibility of crude nutrients and detergent fibre fractions as well as on the pH value and the concentration of short chain fatty acids (SCFA) in rumen fluid were found. The production of SCFA was affected, and the degradation of crude fibre and neutral detergent fibre in the rumen was reduced by the inclusion of FUS at high concentrate proportion. The efficiency of microbial crude protein synthesis was higher in diets with 60% than in diets with 30% concentrates, but was impaired in the presence of FUS in vitro at the high concentrate level. Marginal effects of FUS on the amino acid pattern of microbial protein were detected. It was concluded that the use of FUS in high concentrate diets can influence ruminal fermentation and microbial protein synthesis at a dietary deoxynivalenol concentration below 5 mg/kg dry matter.     

A survey on the feeding of eventing horses during competition

Summary This study aims at the comparison of the actual feeding of horses with the recommendations from the literature, and it studies the effects of feeding and exercise on several blood metabolic parameters before and after exercise. Blood samples were collected from 25 horses during one‐star eventing competitions and evaluated for blood glucose, insulin, lactate, free fatty acids and triglyceride levels. Questionnaires on the feeding practices of the horses were evaluated. The questionnaires revealed that during training, and on tournament days, horses received on average 4.3 kg of concentrate per day (min. 1.54 kg, max. 8 kg). The statistical analysis showed no significant effect of the amount of concentrate fed before exercise on the measured blood values. Oil was supplied as a supplementary energy source to 30% of the horses, but most of them only received very small quantities (0.02–0.4 l/day). Five horses (20%) had no access to salt supplements at all, and eleven horses (45%) had no access to salt on tournament days. Fifteen horses (60%) were supplied with mineral feed. Twenty‐one horses (84%) had daily access to pasture during the training period. During competition, 55% of the horses received roughage ad libitum, compared with 37% during training. The majority of the horses received less roughage on days before the cross‐country competition. It could not be ascertained whether feeding a large amounts of roughage had a beneficial effect on performance, because only a few horses in this study were fed with very restrictive roughage. Feeding of most of the horses was in agreement with the recommendations from the literature, except the need for sodium and chloride. The sodium and chloride need for sport horses may be overestimated in literature and needs to be re‐evaluated.     

不同粗饲料品质（GI）与不同精料给量水平对奶牛生产性能影响的研究

为了完善二代GI技术标准体系,建立以粗饲料GI和产奶水平为参数的预测奶牛日粮科学精饲料给量模型。试验选取36头健康的泌乳中期中国荷斯坦奶牛,根据产奶量、泌乳天数、胎次相近的原则,随机分成3个大组,每个大组又分为3个小组,每个小组含4头奶牛。第1大组的粗饲料为黄贮,精、粗饲料比分别为55：45、57．5：42．5、60：40．标记为A1、A2、A3;第2大组为黄贮加羊草,精、粗饲料比分别为55：45、57．5：42．5、60：40,标记为B1、B2、B3;第3大组为全株玉米青贮加羊草,精、粗饲料比分别为55：45、57．5：42．5、60：40,标记为C1、C2、C3。研究不同粗饲料水平以及不同精料给量下,对泌乳奶牛生产性能的影响。结果表明,随着精料比例的增加,乳蛋白、乳糖和产奶量呈上升趋势．而乳脂呈下降趋势;精、粗饲料比对产奶量有显著影响（P〈0．05）,对乳成分有一定的影响（P〉0．05）;随着粗饲料品质（GI）的提高,乳脂和产奶量呈上升趋势,乳蛋白和乳糖呈下降趋势,但是对乳脂、乳蛋白和乳糖的影响不显著（P〉0．05）,对产奶量的影响显著（P〈0．05）。     

自配精料的原料成本比较与选择

通过市场上奶牛精料常规原料价格,计算出每单位奶牛能量单位(NND)和粗蛋白质(CP)的平均价格。根据饲料原料中的NND和CP含量,可计算出各种饲料的比较值,即精确得到精料原料的比较价格。在充分考虑原料适口性、可得性及有无毒性等前提因素下,选择低成本的原料配制奶牛精料补充料,可降低饲料配方成本,提高奶牛养殖效益。     

根轨迹法在控制车辆纵向角振动中的应用

为研究控制轻型车纵向用振动的作用机理,建立了二自由度车辆振动系统模型,利用控制理论的根轨迹法,分析了悬架刚度变化对系统瞬态性能的影响,确定了前、后悬架刚度的取值范围。     

Nutritive Value of Four Soybean Products in Diets for Atlantic Salmon (Salmo salar,L.)

Abstract

Four processed soybean products were evaluated as protein sources for Atlantic salmon: solvent-extracted soybean meal (SBM44), dehulled and solvent-extracted soybean meal (SBM50), dehulled full-fat soybean meal (FFSBM) and soybean concentrate (SBC). The soybean products replaced high-quality fish meal at levels corresponding to 0, 14, 28, 42 and 56% soybean protein of total protein.

Dietary inclusion of SBC, at the expense of fish meal, did not affect weight gain, carcass lipids, fecal excretion of nutrients or fecal dry matter content significantly. The nutritive value of the SBC protein appeared comparable to that of the fish meal. The three other soybean products impaired performance increasingly with increasing levels of inclusion, indicating lower nutritive value than for the fish meal. The favourable results seen with SBC indicated a great potential of soybean to become an important protein source for Atlantic salmon through improved processing.     

Feed consumption,diet digestibility and mineral utilization in captive blackbuck (Antelope cervicapra) fed different levels of concentrates

A feeding trial was conducted to know the level of concentrates in the diet of Antelope cervicapra at which diet digestibility and mineral utilization were optimum. Fifteen blackbucks (25–33 kg BW) were distributed into three groups of five each. Fresh oat (Avena sativa) and berseem (Trifolium alexandrinum) fodders were offered ad libitum to all the animals. In addition, animals in groups II and III received concentrate mixture at the rate of 0.5 and 1% of BW, whereas animals in group I received no concentrates. As the level of concentrates increased, consumption of fodder decreased resulting in decreased consumption of neutral detergent fibre (NDFom), acid detergent fibre (ADFom), hemicellulose and cellulose. However, overall total dry matter (DM) and organic matter (OM) intake was not significantly different between the groups. Digestibility of DM, OM and gross energy (GE) increased while that of NDFom and ADFom decreased with increased level of concentrates in the diet. Intake of P, Zn, Cu and Mn increased with increased level of concentrate supplementation; however, consumption of Ca and Fe followed the reverse trend. Absorption of P and Zn increased with increased level of concentrate supplementation. Serum concentration of Zn increased when concentrate was supplemented at the rate of 0.5% BW beyond which there was no further improvement. Increasing the level of concentrates in the diet was resulted in increased serum glucose and cholesterol levels. Forage‐only diet was inadequate in supply of energy, P and zinc. Supplementation of concentrates at the rate of 0.5% BW was able to meet the requirement of these nutrients. Supplementation at the rate of 1% BW supplied energy and P in excess of requirement. It was concluded that the feeding of concentrates to the captive blackbuck fed forage‐based diets should be restricted to 0.5% of BW.     

底栖硅藻悬浮培养条件及活性物质研究进展

底栖硅藻作为鲍鱼和海参的主要饵料,对鲍苗和海参的生长、变形和发育有极其重要的作用。从藻体中提取的活性成分具有独特的营养和药用价值,被广泛应用于许多领域。综述了悬浮培养条件对海洋底栖硅藻的生长和营养成分的影响,旨在为大规模悬浮培养底栖硅藻及其活性物质研究提供依据。     

肉羊精料可代谢蛋白质预测模型的建立

目的 在通过概略养分或可消化养分建立肉用绵羊常用精饲料可代谢蛋白质（metabolic protein, MP）的预测模型,为动物日粮的科学配置提供依据。方法 试验选用14月龄,平均体重为（49.27±3.12）kg的安装有永久性瘤胃瘘管的杜寒杂交1代肉用羯羊6只,采用尼龙袋法和改进三步体外法测定10种精饲料的瘤胃有效降解率、瘤胃非降解蛋白质（undegraded dietary protein, UDP）及UDP小肠消化率;另外选用10只体况健康、平均体重（47.43±4.41）kg的杜寒杂交成年公羊分11期进行消化代谢试验,设11个处理组,其中1个基础饲粮组和10个试验饲粮组,试验组饲粮分别由高粱、玉米、大麦、小麦、燕麦、菜籽粕、花生粕、棉籽粕、豆粕及玉米酒糟（distillers dried grains with solubles, DDGS）等替换基础饲粮中羊 草、玉米和豆粕,每个处理10个重复,每个重复1只羊,每期饲喂20 d,其中预试期15 d,正试期5 d。试验羊提前打好耳号,使用伊维菌素进行驱虫,单栏饲养。由于各组饲粮营养成分存在差异造成采食量不同,在预饲期观察并确定最低组的采食量作为限喂量,每天饲喂两次,分别于8:00、16:30饲喂,每次饲喂600 g,自由饮水。采用全收粪尿法测定养分表观消化率和尿嘌呤衍生物法（purine derivative,PD）测定微生物合成蛋白质（microbial synthetic protein, MCP）,通过养分含量或可消化养分建立MP的预测模型。试验数据采用SAS 9.1中的NLIN程序计算a、b、c值和直线回归与多元回归程序分析建立MP估测模型,单因素方差分析（one-way ANOVA, LSD）进行显著性检验结果 饲料的粗蛋白质（CP）瘤胃降解率和UDP小肠消化率均因饲料种类不同而异,高蛋白饲料的CP瘤胃降解率和UDP小肠消化率较高,10种精饲料的CP瘤胃有效降解率的范围在43.71%—60.87%之间,UDP小肠消化率的范围在80.10%—92.86%之间,其中燕麦饲料的瘤胃有效降解率显著高于其他9种饲料 (P＜0.001),而其UDP小肠消化率显著低于其他9种饲料 (P＜0.001);饲粮组成不同,各营养物质的表观消化率不同;瘤胃可降解蛋白质与瘤胃非降解蛋白质比例的变化,不会对全消化道养分的表观消化率产生显著影响;本研究中10种饲料的MP与DP的比例范围在50.96%—62.33%之间,基于饲粮CP（%）含量预测可消化蛋白质（DP,%）的模型是DP=0.895×CP-2.663（R ²=0.994,n=10,P＜0.001）;基于养分含量（%）和可消化养分（%）建立的MP（g·kg ^-1 DM）预测模型分别是：MP=5.323×CP-14.374 (R ²=0.994,n=10,P＜0.001)和MP=5.899×DP+2.077 (R ²=0.984,n=10,P＜0.001)。 结论 饲粮中的粗蛋白质含量与可消化蛋白质存在强相关性;饲粮中概略养分含量和可消化养分与MP存在相关性,可以通过饲粮概略养分含量或可消化养分比较准确地估测精饲料的MP值。