Impacts of animal science research on United States sheep production and predictions for the future

One hundred years ago, there were more than 48 million sheep in the United States. In 1910, they were valued at $4/head, with 43% of income coming from the sale of sheep, lambs, and meat and 57% coming from wool. Over the years, fluctuations in this ratio have challenged the breeder and researcher alike. By 2007, sheep numbers had declined to 6.2 million, with the average sheep shearing 3.4 kg of wool (representing <10% of income), 0.2 kg more than in 1909 but 0.5 kg less than fleeces in 1955. Sheep operations have declined by more than 170,000 in the past 40 yr. A cursory examination of this information might lead one to conclude that animal science research has made little impact on sheep production in the United States. On the contrary, lamb crops in the new millennium (range = 109 to 115%) are greater than those recorded in the 1920s (85 to 89%) and dressed lamb weights increased from 18 to 32 kg from 1940 to the present. In the past century, researchers conducted thousands of investigations, with progress reported in new, existing, and crossbreed evaluations, quantitative and molecular genetics, selection, nutrition, fiber, meat, hides, milk, growth, physiology, reproduction, endocrinology, management, behavior, the environment, disease, pharmacology, toxicology, and range, pasture, and forage utilization such that a vast amount of new information was accrued. Our understanding of sheep has benefited also from research conducted on other species, and vice versa. Many factors that have contributed to the decline in the sheep industry are not influenced easily by academic research (e.g., low per capita consumption of lamb meat, predation, reluctance to adopt new technologies, cost and availability of laborers with sheep-related skills, and fewer young people pursuing careers in agriculture). The size of the US sheep industry is expected to remain stable, with possible slow growth in the foreseeable future. To remain profitable, producers will take advantage of new (or previously unused) technologies, the desire of the public for things natural, domestic niche and international fiber markets, and the ability of the sheep to control noxious weeds and thrive in suboptimal ecosystems.     

营养物质对动物免疫功能的影响

营养物质是动物维持生命活动和进行生产的物质基础．而动物健康是高效生产的前提条件。在畜禽生产中，动物的健康不断地受到各种不同因素的威胁。动物抵御这些不良因素的机制是免疫系统段免疫反应。当动物受到不良因素侵袭时，免疫系统活化。产生免疫反应。消除入侵因子，维持机体健康。如果此过程失调，动物机体就出现代谢紊乱．表现出临床疾病。     

牛磺酸在动物营养中的作用

牛磺酸是具有简单化学结构的含硫氨基酸 ,它以游离形式大量存在于人和哺乳动物几乎所有的脏器中 ,其中以脑、心脏和肌肉组织中含量最高 ,是人及动物的重要营养物质。人和动物必须从外界摄取一定量的牛磺酸 ,但也能通过粒细胞代谢Ｌ -半胱氨酸或其他方式合成一定量的牛磺酸 ,但是合成的量很有限。因此 ,美国、日本等发达国家早已规定在全部婴幼儿乳制品中添加牛磺酸 ,目前我国牛磺酸的年生产量为 1 0 0 0 0ｔ左右 ,绝大部分用于出口。现就牛磺酸在动物营养中的作用研究作一综述。1　牛磺酸生产技术1 1　生物提取法　用生物原料生产牛磺酸是…     

功能性饲料--叶黄素、铬等对动物保健和生产性能的营养趋势

近年来“功能性食品”这个词语在食品工业引起了不小的轰动,这种食品号称可以通过食用添加了某种对人体健康状况有益的营养增强剂来提高人类的健康水平。遗憾的是,功能性食品对消费者的宣传,并没有相应的科研成果支持。然而,当“功能性食品”在向人类描述一个食品科学的重要领域时,这个词语显示出有助于描述一门有关畜产品前沿科学的作用。人类的食品和动物的饲料都包含着数以千计的直接或间接与基础代谢有关系的单独分子,动物饲料配方的难点和关键在于弄清楚如何测定和利用这些分子对食用动物的有益作用。1功能性饲料——将是下一个突破点…     

蛋白质营养对动物繁殖性能的影响

<正>营养物质对动物正常的生理机能是必需的,所有的营养物质对动物的繁殖总有着直接或间接的影响。临床上常见的营养缺乏导致的繁殖障碍有饲料量不     

Interaction of protein nutrition and laidlomycin on feedlot growth performance and digestive function in Holstein steers

Two isonitrogenous diets (12.5% CP) containing 20 (20% NPN) or 40% (40% NPN) of the N as nonprotein N were evaluated with 0 or 10 mg laidlomycin propionate (LP)/kg in a 2 x 2 factorial arrangement. Changes in dietary NPN:N ratio were developed by partial substitution of urea N for fish meal N. In Trial 1, four Holstein steers (349 kg) with cannulas in the rumen and proximal duodenum were used to evaluate treatment effects on digestive function. Total tract OM digestion was slightly greater (1.2%, P < .10) for diets containing 20% of N as NPN, due to greater (3.4%, P < .05) postruminal OM digestion. Supplemental LP decreased passage of microbial N to the small intestine (7.4%, P < .10) and ruminal degradation of dietary CP (DIP, 8.1%, P < .10). Decreasing the NPN:N ratio decreased microbial N flow to the small intestine (7.5%, P < .10) and DIP (15%, P < .01) and increased (6%; P < .05) the flow of indispensable amino acids to the small intestine. Supplemental LP increased (P < .10) ruminal pH. There were no treatment effects (P > .10) on ruminal molar proportions of acetate or propionate. In Trial 2, 120 Holstein steers (122 kg) were used to evaluate treatment effects on growth performance. Decreasing the NPN:N ratio increased ADG (P < .01) by 36, 40, and 16%, respectively, for the initial three 56-d periods of the trial. Overall, ADG was 17% greater (P < .01) for cattle consuming diets containing 20 vs 40% NPN. Decreasing the NPN:N ratio increased (P < .01) gain efficiency by 17 and 14%, respectively, for the initial two 56-d periods. Overall, gain efficiency was 6% greater (P < .01) for diets containing 20% NPN. Dietary NPN:N ratio did not influence (P > .10) the NE value of diets. Supplemental LP did not affect DMI (P > .10) but increased ADG (6%, P < .01) and gain efficiency (5%, P < .05) and decreased (11%, P < .05) the maintenance energy requirements. Protein nutrition limited growth performance of calves receiving the 20% NPN diets during the initial 112 d of the trial. With the 40% NPN diets, protein nutrition limited growth performance throughout most of the trial (d 1 to d 224). We conclude that LP will enhance daily weight gain and gain efficiency of calf-fed Holstein steers. Conventional urea-based diets will not diminish response to LP, although they may not meet the metabolizable amino acid requirements of calf-fed Holsteins during the first three-quarters of the feeding period.     

Influence of body condition at calving and postpartum nutrition on endocrine function and reproductive performance of primiparous beef cows

The influences of body condition score (BCS) at calving and postpartum nutrition on endocrine and ovarian functions, and reproductive performance, were determined by randomly allocating thin (mean BCS = 4.4 +/- 0.1) or moderate condition (mean BCS = 5.1 +/- 0.1) Angus x Hereford primiparous cows to receive one of two nutritional treatments after calving. Cows were fed to gain either 0.45 kg/d (M, n = 17) or 0.90 kg/d (H, n = 17) for the first 71 +/- 3 d postpartum. All cows were then fed the M diet until 21 d after the first estrus. A replication (yr 2; M, n = 25; H, n = 23) was also used to evaluate reproductive characteristics. Concentrations of IGF-I, leptin, insulin, glucose, NEFA, and thyroxine were quantified in plasma samples collected weekly during treatment and during 7 wk before the first estrus. Estrous behavior was detected by radiotelemetry, and luteal activity was determined based on concentrations of progesterone in plasma. All cows were bred by AI between 14 and 20 h after onset of estrus, and pregnancy was assessed at 35 to 55 d after AI by ultrasonography. Cows that calved with a BCS of 4 or 5 had similar endocrine function and reproductive performance at the first estrus. During treatment, H cows gained BW and increased BCS (P < 0.01), and had greater (P < 0.05) concentrations of IGF-I, leptin, insulin, glucose, and thyroxine in plasma than M cows. However, during the 7 wk before the first estrus, plasma concentrations of IGF-I, leptin, insulin, glucose, NEFA, and thyroxine were not affected by time. Cows previously on the H treatment had a shorter (P < 0.01) interval to first postpartum estrus and ovulation, and a larger dominant follicle (P < 0.01) at first estrus, than M cows, but duration of estrus and the number of mounts received were not influenced by nutrient intake. Pregnancy rate at the first estrus was greater (P < 0.03) for H (76%, n = 38) than for M (58%, n = 33) cows. Increased nutrient intake after calving stimulated secretion of anabolic hormones, promoted fat deposition, shortened the postpartum interval to estrus, and increased pregnancy rate at the first estrus. Concentrations of IGF-I and leptin in plasma were constant during 7 wk before the first estrus, indicating that acute changes in these hormones are not associated with the resumption of ovarian function in primiparous beef cows.     

Probiotics in animal nutrition: a review

The normal microflora colonizing the digestive tract in livestock species at five to six days after birth can be summarized as following: 400 to 500 different bacterial strains for a total count of 10(14) bacteriae. The role of the gut flora is multifarious: fermentation of feed compounds, induction of anatomical and physiological changes in the intestinal cell wall structure, increase in animal resistance against enteropathogenic bacteriae, etc. In the present review, the numerous hypotheses for explaining the beneficial effects of probiotics on zootechnical performances and also the healthy aspects for men and animals are summarized, and the possible mechanisms of bacterial attachment are enumerated. The different assumptions on mode of action and fixation mechanisms of probiotics in the gut are critically discussed, and the required characteristics of the ideal probiotic are listed. Finally, some zootechnical results obtained with lactic acid bacteria are shown for calves, piglets and broilers.     

大豆黄酮的营养功能及对动物生产性能的影响

1 大豆黄酮的概述大豆黄酮（Daidzein,DA）又称大豆甙元或葛根黄豆甙元．是异黄酮类植物雌激素中的一种．主要存在于大豆及其豆科植物中。其化学名称为4,7-二羟基异黄酮,在常温下为白色粉末,无味,无毒．不溶于水．在醇和酮类溶剂中具有一定的溶解度．极易溶于二甲基亚砜。大豆黄酮在体内的吸收和代谢速率与动物的种类有关．一般情况下单胃动物慢于复胃动物。不同个体与种类的动物吸收大豆黄酮的能力以及吸收后在体内的代谢程度存在显著差异。     

放牧率对绵羊体重及繁殖性能的影响

通过不同放牧率对内蒙古本地绵羊(母羊)连续2年(2008～2009)的体重和繁殖性能的影响的研究表明:(1)在试验期内,随着时间的推移,不同放牧率下的绵羊体重总体上都呈上升趋势;间隔1个放牧率或以上的处理间,存在不同程度的显著性差异;(2)绵羊的个体增重与放牧率之间存在负相关关系;而公顷增重与放牧率的关系符合二次曲线关系,在达到公顷最大增重前,随着放牧率的增大而增大,之后随着放牧率的增大减小;(3)单位家畜增重和单位面积增重的交点的生态学意义在于放牧率为1羊/hm2,公顷增重和家畜个体增重相同;单位家畜个体增重对应的畜产品最优放牧率为0.50羊/hm2,单位面积家畜最大增重对应的畜产品最优放牧率为2.38羊/hm2;(4)过高的放牧率导致绵羊出现空怀现象及产羔率下降;羔羊的初生重和个体增重均随着放牧率的增大而减小,但其显著性差异仅表现在较高的放牧率与较低的放牧率之间,而在相邻放牧率间差异不显著。     

加工工艺对饲料营养价值及动物生产性能的影响

饲料是畜禽生产上开支最大的一项，在我国饲料支出约占总成本的６５％～７０％，通过恰当的加工方法可以获得较好的经济效益。饲料加工的目的正是为了充分发挥饲料营养价值的潜力，提高产品质量和饲养效果。饲料加工对动物营养的影响一直是饲料加工工艺学家和动物营养学家关心的问题，将加工工艺学和动物营养学有机结合起来能够更大提高动物生产性能。１粉碎粉碎的主要目的是增加饲料接触消化酶的表面积，以使之更易于消化，这也是饲料搅拌、制粒和接受其它处理所必需的。目前许多研究结果表明：粉碎对饲料营养价值和畜禽的生产性能有明显的…     

Delayed feeding of first colostrum: are there prolonged effects on haematological, metabolic and endocrine parameters and on growth performance in calves?

To test the hypothesis that delaying first colostrum feeding of calves after birth exerts long-lasting effects on haematological, metabolic and endocrine traits and on growth performance, neonatal calves were fed first colostrum at 0–2 and 24–25 h after birth. Delayed feeding of first colostrum for 24–25 h after birth caused reduced plasma levels of total protein and globulin for up to 30 days and of insulin-like growth factor-I for up to 7 days, whereas concentrations of nonesterified fatty acids were elevated during the first day of life. There were no significant effects of delaying feeding for 24–25 h on leucocyte and erythrocyte number, packed cell volume and on haemoglobin levels and on plasma concentrations of albumin, urea, glucose, triglycerides, phospholipids, cholesterol, insulin, growth hormone, 3.5.3'-triiodothyronine and thyroxine and on growth performance. Thus, calves fed first colostrum with a delay of 24–25 h after birth were able to compensate rapidly for nutritional deficiencies on day 1 of life, i.e. there was no evidence for permanent imprinting of haematological, metabolic and of endocrine traits by starvation on the first day of life.     

肌肽对肉鸡生长性能及内分泌激素的影响

将1日龄AA肉鸡400只,随机分成4组.1～4组肌肽添加剂量分别为0、20、40和60 mg/L,于每周末测定周增重、料重比、小肠发育或血清激素水平.结果显示,肌肤各组的周增重均高于对照组.但4～6周差异不显著(P>0.05).肌肽各组的料重比均低于对照组(P<0.05或P<0.01).肌肽第1周各组不同程度提高小肠各段的相对重,之后出现相反的影响.肌肽处理没有影响生长激素(GH)组间的差异.肌肽各组T3水平除4周高于对照组外(P>0.05),其他均低于对照组,并且第6周差异显著(P<0.05).肌肽各组第4周T4水平低于对照组(P<0.01),而6周时组间没有差异.结果表明,肌肽能够提高肉鸡的生长性能;有效促进雏鸡的小肠生长发育;生长中期肌肤还可使血清T4向T3的转化明显加强.     

中草药对动物生长、内分泌和免疫功能的影响

作者综述了中草药添加剂对动物生长性能、内分泌、免疫功能、细胞因子活性和基因表达的影响.     

氨基酸对妊娠母猪繁殖性能的影响及其作用机理(续完)

<正>上期回顾:上期介绍了母猪窝产仔数受影响的因素、养猪生产中胎儿宫内发育迟缓问题、胎盘在胚胎发育中的作用主氨基酸在胎盘生长中的作用。5氨基酸对胎儿肌肉和脂肪组织生长发育的影响研究表明,妊娠期间母体的蛋白质营养会影响出生后仔猪的肌肉生长和肌内脂肪的含量(Rehfeldt等,2004)。肌细胞和脂肪细胞来源于普通的造血前体细胞     

Thyroid function, metabolic indices and growth performance in pigs fed 00-rapeseed meal

Thyroid function and morphology, liver morphology, some metabolic indices, haematological parameters and growth performance of fattening pigs fed 00-rapeseed meal (00-RPM) were examined. The control group was fed on a standard diet containing 6% sunflower seed meal (SM) during the growing period and 8% during the finishing period. The first experimental group was fed a diet in which SM was replaced by equal (6% and 8%) amounts of 00-RPM. The second experimental group was fed with a higher (8% and 10%) amount of 00-RPM. There were no significant differences between the control and experimental groups in the serum concentrations of triiodothyronine (T3) and thyroxine (T4). Thyroid gland and liver weights were significantly (P < 0.01) higher in both groups fed 00-RPM than in the group fed SM. The epithelium of the thyroid gland was cuboidal or columnar and the follicular area was moderately enlarged in pigs fed 00-RPM. Marked changes in liver histology were not observed. The 00-RPM diet increased (P < 0.01) the serum values of total proteins in the first fattening period. At the end of fattening both groups fed 00-RPM had higher (P < 0.05; P < 0.01) concentrations of plasma glucose than the control group. The inclusion of 10% of 00-RPM during the finishing period increased (P < 0.05) the serum values of insulin. Daily weight gain during the growing and the finishing period was higher (P < 0.05) in the experimental groups than in the control group. The results suggest that 6-10% 00-RPM can be used as a protein source in the diet of fattening pigs without poisonous side effects.     

日粮营养水平对育成滩母羊生长发育的影响

将20只健康、体重相近的7月龄滩母羊随机分为5组,进行单笼饲养,设计5种不同营养水平的日粮分别饲喂5组育成母羊,来探究日粮营养水平对育成期滩母羊生长发育的影响。结果表明:试验Ⅳ组的增重最快,其平均日增重最高达(127.22 g/d);育成羊随着年龄的增长,体重增长速度下降。在本试验条件下,随着日粮营养水平的提高,育成滩母羊的总增重、平均日增重、干物质采食量均显著增加(P0.05),而料重比不断下降。各试验组羊只的体长、体高和管围的变化无显著性差异(P0.05),而胸围的增长幅度有显著性差异(P0.05)。结合日增重、体尺指标、生产性能、经济效益等指标,可知试验Ⅳ组的营养水平(CP:15.94%,ME:10.18 MJ/kg)能显著改善羊只生长发育,提高生产性能,获得最高的经济效益。     

Organic additives used in beef cattle feedlot: Effects on metabolic parameters and animal performance

Organic additives are recently being used in animal diets owing to their ability to control metabolic issues and result in better animal performance. Specifically, the organic additive Fator P^® presents an additional advantage that is to cause a lesser greenhouse gas emission. This study evaluated whether Fator P^® intake changes ruminal parameters or animal performance of beef cattle. Evaluations were carried out in a feedlot experiment divided into growing (46 days; two diets [control mix—CM and standard mix—SM] and finishing (lasted 83 days; four diets: CM, SM, Fator P^® + virginiamycin, and Fator P^® alone [FP]) trials. Animal performance study involved 48 animals allocated to 12 collective pens in completely randomized experimental design. Ruminal parameters were evaluated in separate metabolism study developed carried out using individual pen with four steers. During growing trial, FP diet resulted in higher (p < 0.05) dry matter intake (DMI) and ruminating time. In the finishing trial, diets containing Fator P^® resulted in higher DMI than obtained with CM. Most of the ruminal parameters did not differ (p > 0.05) among dietary treatments. Therefore, Fator P^® represents a viable and safe strategy for supplementation to beef cattle finished using high‐concentrate diet in feedlot systems.     

Influence of feeding different amounts of first colostrum on metabolic, endocrine, and health status and on growth performance in neonatal calves

Colostrum intake is important for health and postnatal development of neonatal calves. We studied the effects of enhanced first colostrum feeding on growth, health status, and metabolic and endocrine traits in calves during their 1st wk of life. Calves of group CL (GrCL; n = 7) were fed colostrum of milkings 1 to 6 twice daily during the first 3 d of life, followed by milk replacer (MR) up to d 7. Calves of group CH (GrCH; n = 7) were fed colostrum of the first milking during the first 3 d and then colostrum (of the first milking) twice daily, which on d 4, 5, 6, and 7 was diluted with 25, 50, 75, and 75 parts of MR, respectively. Pre- and postprandial blood samples were taken on d 1, 2, 3, and 7 for the determination of various metabolic and endocrine traits, and on d 5 intestinal absorption capacity was measured using the xylose absorption test. Rectal temperatures and fecal scores were higher (P < .05) in GrCH than in GrCL. Plasma concentrations of total protein and albumin were higher (P < .05) on d 7, IgG on d 2 and 3, and urea on d 2, 3, and 7 in GrCH than in GrCL. Plasma concentrations of triglycerides were higher (P < .05) on d 2 and of phospholipids and cholesterol were higher (P < .01) on d 7 in GrCH than in GrCL. Plasma insulin and glucagon concentrations were higher (P < .05) in GrCH than in GrCL, whereas prolactin and growth hormone concentrations were higher (P < .05) in GrCL than in GrCH. Enhanced colostrum intake had no effects on xylose absorption on d 5. Higher plasma protein, urea, and lipid concentrations in GrCH partly mirrored higher protein and fat intake but additionally pointed to higher protein synthesis and lipid turnover.