Influence of dietary magnesium content on laying performance and egg shell magnesium content in the domestic hen

1. The effects of feeding diets containing various amounts of magnesium on laying performance in the domestic hen were investigated.

2. A reduction in egg number, egg mass, egg shell thickness and egg shell magnesium content occurred in birds receiving diets containing either 207 or 132 mg Mg²⁺/kg even though the duration of egg formation was unaffected.

3. The progressive increase in magnesium content normally observed towards the outer surface of the hen's egg shell was not present in birds receiving a diet containing 207 mg Mg²⁺/kg.     

Effect of erythromycin on L-threonine transport in rabbit jejunum in vitro

Several antibiotics characterized by different molecular structures are known to affect some intestinal activities. Some of them have been described as inhibitors of the intestinal sugar and amino acid transport with different mechanisms. Erythromycin (EM) is a macrolide antibiotic acting as a motilin agonist and thus stimulating the gastrointestinal motor activity. Since several substances which increase the motor activity of the gastrointestinal tract may produce effects on the intestinal absorption of nutrients, the present study has been carried out to determine whether erythromycin affects the L-threonine intestinal absorption. The results obtained indicate that erythromycin diminishes the L-threonine intestinal transport, probably at the mucosal border level. Two groups of experiments carried out, with Na(+)-deprived medium and ouabain-enriched medium, might indicate that erythromycin action could be due to either a direct or an indirect action on the Na(+)-dependent L-threonine transport located in the brush border.     

Effects of high dietary sodium chloride content on performance and sodium and potassium balance in growing pigs

Thirty castrated male Moo Lath pigs (6–8 weeks of age) were used in a 15-week growth trial to study the effect of high dietary sodium chloride (NaCl) content on feed and water intake, performance, sodium (Na) and potassium (K) balance, and plasma aldosterone concentration. The pigs were randomly allocated (ten per treatment) to diets containing 0.24 % Na (Na0.24), 0.28 % Na (Na0.28), and 0.32 % Na (Na0.32) per kg diet. Feed and water was provided ad libitum, and water consumption, feed offered, and feed residues were recorded daily. Every third week, the pigs were weighed, blood samples were collected, and a 3-day total collection of urine and feces was performed. Water intake was higher (P?=?0.001) in pigs fed with diets Na0.28 (3.7 L/day) and Na0.32 (3.9 L/day) than in pigs fed with diet Na0.24 (3.4 L/day), and dry matter (DM) intake was higher on diet Na0.32 (P?=?0.041) than on the other diets. The average daily body weight (BW) gain was higher on diet Na0.32 than on the other diets (P?=?0.031). The feed conversion ratio (in kilogram feed DM to kilogram BW gain) was 4.6, 4.6, and 4.1 on treatments Na0.24, Na0.28, and Na0.32, respectively (P?=?0.14). The highest Na balance was observed on diet Na0.32 followed by diets Na0.28 and Na0.24 (P?<?0.001), while there was no treatment-related pattern for the K balance. The Na/K ratio in feces and urine increased (P?<?0.001), and the K/Na ratio in feces (P?<?0.001) decreased with increasing Na content in the diet. Plasma aldosterone concentration decreased (P?<?0.001) with increasing dietary content of Na. These results indicate that high NaCl intake and free access to water will increase Na balance but do not negatively influence feed intake and performance of growing local pigs.     

Influence of variable content of dietary zinc on copper metabolism of weanling foals

The influence of variable zinc content (29.1, 250, 1,000 and 2,000 mg/kg of dry weight) in a basic diet containing 7.7 mg of copper/kg on the ability of weanling foals to maintain normal copper balance was investigated. Serum copper and zinc concentrations were monitored, and terminal hepatic copper and zinc contents were measured in 4 weanling foals fed the basic diet containing 29.1 mg of zinc/kg and in 2 foals each fed the higher-zinc diets. Foals fed the lower-zinc diets (29.1 and 250 mg/kg) maintained normal serum copper and zinc concentrations for 14 to 15 weeks, whereas those fed the 2 higher-zinc diets became hypocupremic within 5 to 6 weeks and were lame within 6 weeks, owing to cartilaginous disease characteristic of osteochondritis dissecans. Serum zinc concentration in the foals fed the 2 higher-zinc diets increased to greater than 2 micrograms/ml within 2 weeks. Foals fed the high-zinc diets became lame after serum copper concentration had remained at 0.3 micrograms/ml for greater than 1 week. Serum copper concentration in these arthritic foals was less than or equal to 0.2 micrograms/ml at the end of the study. In lame foals, fractures of the cartilage of the articular and growth physes occurred through the zone of hypertrophic cells, and varied from bilateral to unilateral and from small to large. Free masses and flaps of cartilage attached to one side were numerous.     

Effects of age and zinc supplementation on transport properties in the jejunum of piglets

Zinc is effective in the prevention and treatment of post‐weaning diarrhoea and in promoting piglet growth. Its effects on the absorption of nutrients and the secretory capacity of the intestinal epithelium are controversial. We investigated the effects of age, dietary pharmacological zinc supplementation and acute zinc exposure in vitro on small‐intestinal transport properties of weaned piglets. We further examined whether the effect of zinc on secretory responses depended on the pathway by which chloride secretion is activated. A total of 96 piglets were weaned at 26 days of age and allocated to diets containing three different levels of zinc oxide (50, 150 and 2500 ppm). At the age of 32, 39, 46 and 53 days, piglets were killed, and isolated epithelia from the mid‐jejunum were used for intestinal transport studies in conventional Ussing chambers, with 23 μm ZnSO₄ being added to the serosal side for testing acute effects. Absorptive transport was stimulated by mucosal addition of d ‐glucose or l ‐glutamine. Secretion was activated by serosal addition of prostaglandin E₂, carbachol or by mucosal application of Escherichia coli heat‐stable enterotoxin (St_p). Jejunal transport properties showed significant age‐dependent alterations (p < 0.03). Both absorptive and secretory responses were highest in the youngest piglets (32 d). The dietary zinc supplementation had no significant influence on jejunal absorptive and secretory responses. However, the pre‐treatment of epithelia with ZnSO₄ in vitro led to a small but significant decrease in both absorptive and secretory capacities (p < 0.05), with an exception for carbachol (p = 0.07). The results showed that, in piglets, chronic supplementation with zinc did not sustainably influence the jejunal transport properties in the post‐weaning phase. Because transport properties are influenced by the addition of zinc in vitro, we suggest that possible epithelial effects of zinc depend on the acute presence of this ion.     

Influence of maternal dietary fat upon rat pups.

Mother rats were fed purified rations containing different fats during gestation and lactation and at 1 day after parturition. Litter sizes were reduced to 2 male and 2 female pups. The behavior and the brain chemical composition of these selected pups were compared with similarly selected pups from dams fed a commercial ration. All offspring were fed a commercial ration after weaning. Pups from dams fed 20% safflower oil were similar to controls. Feeding 20% cocoa butter to dams resulted in pups with reduced exploratory activity and with a rapid learning performance in a T-maze, employing the aversive stimulation of an electrical shock. Feeding dams a fat-free ration produced pups which had reduced rates of growth, small brains at 2 months of age, and low brain concentrations of cholesterol, DNA, and RNA.     

日粮钾水平对乳牛红细胞钾含量的影响

随机选择14头奶牛,作日粮中不同钾水平对红细胞钾水平影响的试验。试验期在基础日粮中分别添加氯化钾60,100,160g/·头,测定各添加阶段奶牛红细胞钾,血浆钾和全血钾含量。结果表明,日粮钾水平对红细胞钾含量无显著影响(P>0．05),但使血浆钾及全血钾含量升高     

Influence of pre-fast dietary roughage content on recovery from feed and water deprivation in beef steers

Sixty steer calves of mixed British breeding averaging 268 kg were randomly assigned to four treatment groups of 15 calves each to determine the influence of pre-fast dietary roughage content on recovery from feed and water deprivation. Three groups were fed diets containing either 84 (HR), 60 (MR) or 35% (LR) roughage at 1.75% of body weight for 3 d. Calves in these three groups were deprived of feed and water for 24 h, limit-refed and watered for 24 h, and deprived of feed and water for 48 h (deprivation). Calves were then fed the MR diet ad libitum for 2 wk. The fourth group of control steers was continuously fed the MR diet throughout the experiment. Realimentation weight gains and feed intakes were not affected by pre-fast diet roughage content. Blood packed cell volume increased (P less than .05) during deprivation. Blood potassium was not affected by deprivation but declined (P less than .05) upon refeeding. Plasma urea-N increased (P less than .05) during deprivation but returned to pre-fast concentrations by d 3 of realimentation. Ruminal volume was not significantly affected by deprivation but increased (P less than .05) by 50 to 100% upon refeeding. Ruminal fluid total volatile fatty acid (VFA) concentrations declined (P less than .05) during deprivation. On d 3 of realimentation, a linear contrast (P less than .05) was observed between total VFA concentrations and the pre-fast diet roughage content.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of dietary electrolyte balance, source of added potassium and anticoccidial agents on the performance of male broilers

1. The performance of 1680 male broiler chickens was measured from one to 42 d of age. They were given diets with three (125, 165 and 205 mEq/kg) electrolyte balances (sodium + potassium - chloride), two sources of added potassium (carbonate or sulphate) and two anticoccidial agents (90 mg/kg of either monensin or lasalocid). 2. The dietary treatments had no significant effects on the growth performance of broiler chickens in the starter phase. 3. In the finisher phase, the chickens given the diets containing lasalocid utilised food less efficiently that those given the diets containing monensin. 4. There were significant interactions between dietary electrolyte balance and source of added potassium on body weight gains and food:gain ratios in the finisher phase. In diets with an electrolyte balance of 205 mEq/kg, the inclusion of potassium sulphate instead of potassium carbonate increased body weight gains by 3.4% and reduced food:gain ratios by 4.6%. 5. The body weight gains of chickens given the finisher diets containing lasalocid and added potassium carbonate were reduced by 2.6% compared to those of chickens given the diets containing monensin or added potassium sulphate. 6. The litter moisture content was higher in pens with chickens on the diets with an electrolyte balance of 205 mEq/kg than on the diets with either 125 or 165 mEq/kg. Both lasalocid and potassium sulphate tended to increase the litter moisture content. 7. It may be concluded that the inclusion of 90 mg/kg of either monensin or lasalocid in broiler diets does not alter the balance of electrolytes required for optimum growth performance of broiler chickens.     

Influence of dietary crude protein content on fattening performance and nitrogen excretion of Holstein steers

The objective was to investigate the influence of crude protein (CP) content in a fattening diet on feed intake, body weight gain, nitrogen excretion, and carcass traits in Holstein steers. Steers (initial body weight 241 ± 26 kg) consumed feed with the following CP content: (a) 17.7% during the early period (from 7 to 10 months of age) and 13.9% during the late period (from 11 to 18 months of age) (HIGH, n = 3), and (b) 16.2% during the early period and 12.2% during the late period (LOW, n = 4). The CP intake was lower in the LOW than the HIGH group. Urinary and total nitrogen excretion in the late period tended to be lower (p < .10) in the LOW than the HIGH group. However, growth performance and carcass traits were not affected by dietary CP content. Free histidine and total amino acid contents in the longissimus thoracis muscle tended to be higher (p < .10) in the HIGH than the LOW group, however, the CP contents were not affected by dietary CP content. The results of this experiment suggest that decreasing dietary CP to 16% (early period) or 12% (late period) of dry matter would reduce nitrogen excretion from Holstein fattening farms without affecting productivity.     

Influence of a xylanase feed additive on Lactobacillus species in the jejunum of piglets

rRNA extracts from the jejunum of rearing piglets fed a wheat/rye based diet with or without a xylanase feed additive were hybridized against eight Lactobacillus spp. specific digoxigenin labelled oligonucleotide probes. Known concentrations of sample- or culture RNA extracts were used to calibrate and quantify hybridization signals from different sample extracts and hybridizations. The xylanase feed additive tended to increase total eubacterial rRNA in the terminal jejunum, probably a result of increased Lactobacillus spp. rRNA in the central and terminal jejunum. However, individual animal variations were high. L. reuteri was the major Lactobacillus species followed by L. acidophilus and L. mucosae. L. amylophilus and L. crispatus were not detected in all RNA extracts.The results of this study show that the xylanase feed additive modifies Lactobacillus spp. populations on the species level in piglets in addition to their well known effects on digesta viscosity and nutrient digestibility.The implications of these effects for the intestinal microbiota require further analysis.     

Influence of dietary calcium and phosphorus content in a fixed ratio on growth and development in Great Danes

OBJECTIVE: To study the musculoskeletal development of Great Dane puppies fed various dietary concentrations of calcium (Ca) and phosphorus (P) in fixed ratio by use of dual energy x-ray absorptiometry (DEXA), determination of serum insulin-like growth factor 1 and parathyroid hormone concentrations, radiography, and blood chemistry analysis results. ANIMALS: 32 purebred Great Dane puppies from 4 litters. PROCEDURE: At weaning, puppies were assigned randomly to 1 of 3 diets. Blood was collected for biochemical analyses and hormone assays, and radiography and DEXA were performed through 18 months of age. Changes in body weight, bone mineral content, fat tissue weight, lean mass, result of serum biochemical analyses, hormonal concentrations, and radius lengths were analyzed through 18 months of age. RESULTS: Bone mineral content of puppies correlated positively with Ca and P content of the diets fed. Significant differences between groups in bone mineral content, lean mass, and body fat were apparent early. The disparity among groups increased until 6 months of age and then declined until body composition was no longer different at 12 months of age. Accretion rates for skeletal mineral content, fat, and lean tissue differed from each other and by diet group. CONCLUSIONS AND CLINICAL RELEVANCE: Ca and P concentrations in the diet of young Great Dane puppies are rapidly reflected in the bone mineral content of the puppies until 5 to 6 months of age, after which hormonal regulation adjusts absorption and excretion of these minerals. Appropriate Ca and P concentrations in diets are important in young puppies < 6 months of age.     

Effects of dietary potassium and sodium on magnesium utilization in sheep

Two metabolism trials were conducted to determine the effect of altering dietary Na and K on Mg availability. Three dietary treatments (normal K-normal Na, high K-normal Na and high K-high Na) were imposed upon nine crossbred wether lambs in a randomized block design. Each trial consisted of a 5-d diet adjustment, a 10-d preliminary period and a 5-d collection of feed, feces and urine. Increasing K and Na intake increased the percentage of Mg excreted in feces. Both elevated K and K-Na depressed (P less than .10) urinary Mg excretion, primarily a reflection of depressed Mg absorption in animals fed these diets. Apparent K absorption and retention increased when animals were supplemented with K. Addition of Na to the diet did not alter absorption or retention of K. Apparent K and Na availability increased when K and Na supplements were included in the diet. This increased availability resulted from increased total absorbed K and Na compared with a fixed endogenous excretion. Calcium balance in lambs was not affected by addition of K or Na. Lambs were able to absorb enough Mg from their respective diet to maintain normal serum Mg levels. Addition of Na to a diet high in K did not enhance Mg absorption in lambs.     

施钾水平对甘肃烤烟钾含量及经济效益的影响

针对甘肃烤烟生产中存在的烟叶钾含量低和种植效益不高等问题,于2007年在庆阳市正宁县布置大田试验,在等氮磷用量基础上,研究了施钾水平(0,90,180,270K₂Okg/hm²)对烤烟钾含量及经济效益的影响。结果表明,烟叶钾含量随施钾水平的提高而增加,以施钾量为270K₂Okg/hm²时最高,中部叶片钾含量可达2.11%,接近云南和贵州烟区的烟叶钾含量;不同叶位叶片钾含量对施钾水平的反应不同,以中部叶最为敏感;施用钾肥后,烟株上、中、下部叶片钾含量的高低顺序发生改变。烟叶产量、均价、中上等烟比例和产值等经济效益参数均随施钾水平的提高而持续增加,说明增施钾肥可通过提高产量和改善品质提高烤烟种植的经济效益。在本试验条件下,最佳施钾量可能在270K₂Okg/hm²以上。     

The effect of dietary potassium and chloride on cation-anion balance in swine

The apparent retention and excretion of cations and anions were evaluated in 20 growing pigs to study the mechanisms by which an interaction between dietary K and Cl levels affected growth. All pigs maintained a positive retention of K+ and Cl- regardless of the dietary levels. The K x Cl interaction observed in growth studies previously but not in this study could not be explained by a simple interaction of one ion on the retention of the other. When pooled across dietary Cl levels, an increase in dietary K levels from .10 to .60% resulted in a calculated increase in daily K+ intake of 4.86 meq/kg of BW. Sixty percent (2.99 meq) of the increased K+ intake was excreted in the urine and counterbalanced by a decrease in urine NH4+ (3.06 meq). This decrease in NH4+ excretion could account for essentially all of the increase in N retention (3.51 mmol) observed when dietary K levels were increased from .10 to .60%. Thirty-three percent of the increased K+ intake (1.62 meq) was retained, but the counter ion could not be determined. Retention of Cl- was not changed as dietary K levels were changed. When dietary Cl levels were increased from .03 to .57%, 69% (4.06 meq) of the calculated difference in Cl- intake (5.90 meq) was excreted in the urine, which must have been counterbalanced by a decrease in undetermined organic anions (1.77 meq) and HPO4 = (1.50 meq) excretion, with a tendency for an increased NH4+ (.82 meq) excretion. The counter ions required to balance the increased Cl- retention (1.82 meq) as dietary Cl levels were increased from .03 to .57% could not be identified. Shifts in the retention and urinary excretion of Ca++, Na+, HCO3-, and SO4= did not seem to be quantitatively important in identifying the mechanisms by which dietary K and Cl levels alter growth. Based on these results, we conclude that alterations in growth caused by changes in dietary K and possibly Cl levels are mediated via mechanisms involving renal NH4+ metabolism.     

Effect of water restriction and dietary potassium on nutrient metabolism in lambs

Twenty-four Hampshire X Suffolk wether lambs (40 kg) were used in a 2 X 2 factorial arrangement of treatments to study the influence of water restriction and high levels of dietary K on nutrient utilization. Lambs were offered either a normal K diet (1.86% K) or a high K diet (3.66% K). Additionally, the lambs were offered either a normal quantity of water (previously determined voluntary intake of lambs fed normal K levels) or were restricted to a water intake 80% of normal. Each lamb received 800 g/d of a fescue hay-corn diet (77.5% fescue hay) with an additional 20 g of KCl offered to lambs on high K treatments. The experiment consisted of 14 d of adjustment and 7 d of total collection with blood and ruminal parameters measured on the last day of collection. Both acid detergent fiber digestibility and N balance were reduced (P less than .05) by high K intake. Urinary Mg excretion tended (P greater than .05) to be decreased by water restriction. Plasma Mg concentrations at 2 h post-feeding (PF) tended (P greater than .05) to be reduced by a high K intake at a normal level of water consumption but increased at high K intake when water intake was restricted. A similar pattern was observed for plasma K concentrations. Although high K intake resulted in elevated (P less than .05) ruminal K concentrations both at 2 and 6 h PF, ruminal concentrations of ammonia-N and volatile fatty acids were not affected (P greater than .05) by treatment. These data suggest that nutrient utilization in both the digestive tract and tissues is altered by level of K and modest water restriction.     

中国黑白花奶牛红细胞钾含量遗传性的研究

为了研究中国黑白花奶牛红细胞钾含量的遗传性,在广州、江西和黑龙江采集测定了829头黑白花奶牛的红细胞钾含量.结果表明黑白花奶牛红细胞钾含量呈正态分布,平均值为72.7±11.0mg/dl(33.1mg/dl-182.9mg/dl).同时据18头种公牛及其440头女儿的红细胞钾含量,采用公牛内半同胞资料得红细胞钾含量的遗传力为0.75;据53个母女对细红胞钾含量采用母女回归法得红细胞钾含量的遗传力为0.60.     

Influence of dietary protein content and source on colonic fermentative activity in dogs differing in body size and digestive tolerance

Low-consistency, high-moisture feces have been observed in large dogs (Canis lupus familiaris), compared with small dogs, and particularly in sensitive breeds (e.g., German Shepherd dogs). The aim of this work was to determine if greater colonic protein fermentation is responsible for poorer fecal quality in large sensitive dogs. Twenty-seven bitches were allotted to 4 groups based on size and digestive sensitivity: small, medium, large tolerant, and large sensitive. Five experimental diets varying in protein source [highly digestible wheat gluten (WG) vs. medium digestible poultry meal (PM), and protein concentration from 21.4 to 21.6 (LP) to 38.2 to 39.2% CP (HP)] were tested. Diets were fed for 14 d and followed by a 12-d transition period. Digestive fermentation by-products were investigated in fresh stools [ammonia, phenol, indole, and short chain fatty acids including acetate, propionate, and butyrate (C2 to C4 SCFA), branched-chain fatty acids (BCFA), and valerate] and in urine (phenol and indole). Bacterial populations in feces were identified. The PM diets resulted in greater fecal concentrations of ammonia, BCFA, valerate, indole, and C2 to C4 SCFA than WG diets (P = 0.002, P < 0.001, P = 0.039, P = 0.003, and P = 0.012, respectively). Greater concentrations of ammonia, BCFA, and valerate were found in the feces of dogs fed HP compared with LP diets (P < 0.001, P < 0.001, and P = 0.012, respectively). The concentrations of ammonia, valerate, phenol, and indole in feces of large sensitive dogs were greater (P < 0.001, P < 0.001, P = 0.002, and P = 0.019, respectively) compared with the other groups. The Enterococcus populations were greater in feces of dogs fed with PMHP rather than WGLP diets (P = 0.006). Urinary phenol and indole excretion was greater when dogs were fed PM than WG diets (P < 0.001 and P = 0.038, respectively) and HP than LP diets (P = 0.001 and P = 0.087, respectively). Large sensitive dogs were prone to excrete a greater quantity of phenol in urine (P < 0.001). A diet formulated with highly digestible protein, such as WG, led to reduced concentrations of protein-based fermentation products in feces together with improved fecal quality in dogs, especially in large sensitive ones. Poor fecal quality in large sensitive dogs could be partly related to the pattern of protein fermentation in the hindgut.     

饲粮不同氮硫比对藏羔羊空肠组织形态和空肠微生物区系的影响

肠道是动物重要的消化和吸收的器官.为探究饲粮中不同氮硫比对藏羔羊空肠组织形态和空肠微生物区系的影响,试验选择初始条件相似的60日龄藏羔羊150只,随机分为5组,分别用氮硫质量比为10.5?1(A)、9?1(B)、7.5?1(C)、6?1(D)、4.5?1(E)的饲粮饲养至180日龄,试验期结束每组随机屠宰6只,采集空肠组织和内容物分析饲粮氮硫比对空肠组织形态和空肠微生物菌群结构及功能的影响.结果显示:1)B组和E组的空肠绒毛长度和绒毛宽度显著高于其余3组(P<0.05),并且A、D组的绒毛长度显著高于C组(P<0.05);D组的隐窝深度显著高于其他4组(P<0.05);B、E组的绒毛长度/隐窝深度显著高于A、C、D组(P<0.05);B组和E组的黏膜层厚度显著高于C、D组(P<0.05);B组的肌肉层厚度均显著高于其他组(P<0.05).2)B、E两组的操作分类单元数(operational taxonomic units,OTU)、Chao1指数显著高于A、C组(P<0.05);B、E组的Shannon指数显著高于其他组(P<0.05);C、D两组的Simpson指数显著高于B、E组(P<0.05);B、D、E组的Ace指数显著高于A、C组(P<0.05).3)从门和属水平上分析空肠微生物菌群结构:在门水平下5组的优势菌门均为厚壁菌门(Firmicutes)、放线菌门(Actinobacteria)、拟杆菌门(Bacteroidetes)和变形菌门(Proteobacteria).其中B组厚壁菌门的丰度显著高于C组(P<0.05);A、C组的放线菌门丰度显著高于B、E组(P<0.05);B组和E组拟杆菌门的丰度显著高于A、C两组(P<0.05);E组的变形菌门丰度显著高于B组和D组(P<0.05).在属水平下:5组的优势菌属均为红球菌属(Rhodococcus)、短杆菌属(Brevibacterium)、克里斯滕森氏菌R7菌群(Christensenellaceae-R-7-group)、Quinella属和理研菌科RC9肠道菌群(Rikenellaceae-RC9-gut-group).A、C、D组红球菌属的丰度显著高于B、E组(P<0.05),B组的克里斯滕森氏菌R7菌群丰度显著高于其他组(P<0.05),A、B组的Quinella丰度显著高于D、E组(P<0.05).4)16S rRNA基因组的PICRUSt功能预测结果显示,空肠微生物菌群功能主要集中在转录、碳水化合物运输与代谢、氨基酸的运输与代谢等方面,表明藏羔羊空肠细菌在提高宿主碳水化合物和蛋白质的代谢与吸收方面至关重要.综上,氮硫比在B和D水平下均有利于藏羔羊空肠组织形态的发育,并且可提高空肠微生物菌群多样性和丰富度,从经济效益上考虑,氮硫质量比为9?1时更符合藏羔羊的高效养殖.