Low quality roughages for steers grazing wheat pasture. I. Effect on weight gains and bloat

The effect of feeding low quality roughages (LQR) on live and carcass weight gains and the incidence and severity of bloat of stocker cattle grazed on wheat pasture was evaluated in a 3 yr study. One hundred eighty-five steer calves (172 kg mean initial weight) grazed clean-tilled wheat pasture and were either fed no LQR or had ad libitum access to wheat straw (WS) or sorghum-Sudan hay (SS). Grazing periods were (I) fall grazing, (II) winter grazing, (III) period of lush spring growth of wheat forage and (IV) period of advancing forage maturity and declining quality. Mean dry matter (DM), crude protein and acid detergent fiber (ADF) content (percentage of DM) of wheat forage averaged across years ranged, respectively, from 23.8 to 33.0, 19.8 to 26.4 and 21.5 to 27.7. Mean daily consumption (kg DM/head) of WS and SS by steers ranged from .076 to .100 and .199 to .248, respectively. Live and carcass weight gains of steers during Periods I through III (i.e., the usual wheat pasture grazing period) were not influenced (P greater than .05) by treatments. Carcass weight gains were about 74% of live weight gains. Bloat was observed only during the last 2 wk of Period III of the first year. The incidence (steer days of bloat) and severity (bloat score) of control, WS- and SS-fed steers were 9.5 and 1.2, .5 and .5 and 2.0 and 1.0, and were not different (P greater than .05) among treatments. Intake of WS and SS [g/body weight (BW).75kg] during Periods I to III was, respectively, only about 5 and 12% of roughage intakes (i.e., 37.5 g/BW.75kg) reported in the literature to "effectively control" or aid the prevention of bloat. It seems unlikely that LQR consumed to amounts similar to those of this study would control bloat of stocker cattle on wheat pasture.     

Effects of dietary fat and sire breed on puberty, weight, and reproductive traits of F1 beef heifers

Prepubertal F1 heifers (n = 246; from crossbred dams bred to either Hereford [H], Limousin [L], or Piedmontese [P] sires) were fed 1.9% (LF) or 4.4% (HF) dietary fat from 254+/-4 d of age until they reached puberty or the breeding season started. Safflower seeds (37% oil with 79% linoleic acid) were the added fat source. Blood samples and backfat thickness measurements were obtained from 60 randomly selected heifers representing the sire breeds and diets studied. In addition, five H-sired heifers from both diets were serially bled at 28-d intervals. Total gain, ADG, body condition score, and backfat thickness were affected by sire breed (P < 0.001) but not diet. Backfat thickness was affected (P < 0.01) by the diet x time on feed interaction. Diet did not affect pubertal age (P > 0.10) but tended (P = 0.08) to affect the percentage of heifers pubertal by the beginning of breeding (June 4). Sire breed effects on puberty age at beginning of breeding, percentage pubertal at the beginning of breeding, and puberty age during the entire study were all highly significant. The effect of the diet x sire breed interaction on percentage of heifers pubertal at beginning of breeding (P < 0.05) was 74.4 vs 76.3% in H-sired, 69.8 vs 60.5% in L-sired, and 76.2 vs 97.6% in P-sired heifers (LF vs HF, respectively). Number of AI services per pregnancy and final pregnancy percentage were not affected by diet or the diet x sire breed interaction. Diet affected progesterone (P < 0.05) and cholesterol (P < 0.001) concentrations, and sire breed tended to affect (P = 0.06) cholesterol concentrations. The effect of the diet x time on feed interaction on cholesterol concentrations was highly significant. There were no effects of diet or sample period on insulin or growth hormone concentrations in serially collected blood samples. We conclude that effects of supplemental dietary fat may be breed-dependent and hypothesize that a feeding period of approximately 60 d duration may be more appropriate than the 162 d used in this study.     

饲料来源对育肥湖羊生产性能、养分消化及瘤胃微生物组成的影响

为评价日粮粗饲料来源对育肥湖羊生产性能、养分消化及瘤胃微生物组成的影响。选择60日龄健康湖羊公羔(22.9±1.2) kg 120只,根据体重相近原则随机分成4组,每组5个重复,每个重复6只羊,分别以玉米秸秆(CS)、玉米芯(CC)、葵花籽壳(SH)和油菜秸秆(RS)作为粗饲料来源,添加比例均为20%,4组精料配比一致,预试期7 d,正试期70 d。在饲喂的49~55 d,每组选择5只羊采用全收粪法进行消化代谢试验,测定干物质(DM)、有机物质(OM)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)和氮(N)的表观消化率。试验结束后,每组选择15只羊进行屠宰,采集瘤胃内容物,提取瘤胃微生物DNA,对瘤胃细菌进行绝对定量。结果显示:1)CS组湖羊干物质采食量显著高于其他3组(P<0.05),且末体重和平均日增重显著高于RS组(P<0.05),其他组间差异不显著(P>0.05)。2)CS和CC组湖羊DM和ADF消化率显著高于RS组(P<0.05),且其OM和NDF消化率显著高于SH组和RS组(P<0.05);SH组湖羊N消化率显著高于RS组,其ADF消化率与其他3组湖羊差异均不显著(P>0.05)。3)CS组和CC组湖羊瘤胃中白色瘤胃球菌和普雷沃氏菌数量均显著高于RS组(P<0.05),而SH组湖羊瘤胃中两种细菌的数量与其他3组湖羊均无显著差异(P>0.05),CS组和CC组湖羊瘤胃中黄色瘤胃球菌和产琥珀酸丝状杆菌数量均显著高于SH组和RS组(P<0.05),4组湖羊瘤胃中反刍兽新月单胞菌数量差异不显著(P>0.05)。结果表明:相较于葵花籽壳组日粮和油菜秸秆组日粮,玉米秸秆组和玉米芯组日粮不仅可以确保育肥湖羊的生产性能,并且有利于纤维分解菌的生存,可促进纤维素在瘤胃中的降解。     

饲料来源对育肥湖羊生产性能、养分消化及瘤胃微生物组成的影响

为评价日粮粗饲料来源对育肥湖羊生产性能、养分消化及瘤胃微生物组成的影响。选择60日龄健康湖羊公羔(22.9±1.2) kg 120只,根据体重相近原则随机分成4组,每组5个重复,每个重复6只羊,分别以玉米秸秆(CS)、玉米芯(CC)、葵花籽壳(SH)和油菜秸秆(RS)作为粗饲料来源,添加比例均为20%,4组精料配比一致,预试期7 d,正试期70 d。在饲喂的49～55 d,每组选择5只羊采用全收粪法进行消化代谢试验,测定干物质(DM)、有机物质(OM)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)和氮(N)的表观消化率。试验结束后,每组选择15只羊进行屠宰,采集瘤胃内容物,提取瘤胃微生物DNA,对瘤胃细菌进行绝对定量。结果显示:1)CS组湖羊干物质采食量显著高于其他3组(P<0.05),且末体重和平均日增重显著高于RS组(P<0.05),其他组间差异不显著(P>0.05)。2)CS和CC组湖羊DM和ADF消化率显著高于RS组(P<0.05),且其OM和NDF消化率显著高于SH组和RS组(P<0.05);SH组湖羊N消化率显著高于RS组,其ADF消化率与其他3组湖羊差异均不显著(P>0.05)。3)CS组和CC组湖羊瘤胃中白色瘤胃球菌和普雷沃氏菌数量均显著高于RS组(P<0.05),而SH组湖羊瘤胃中两种细菌的数量与其他3组湖羊均无显著差异(P>0.05),CS组和CC组湖羊瘤胃中黄色瘤胃球菌和产琥珀酸丝状杆菌数量均显著高于SH组和RS组(P<0.05),4组湖羊瘤胃中反刍兽新月单胞菌数量差异不显著(P>0.05)。结果表明:相较于葵花籽壳组日粮和油菜秸秆组日粮,玉米秸秆组和玉米芯组日粮不仅可以确保育肥湖羊的生产性能,并且有利于纤维分解菌的生存,可促进纤维素在瘤胃中的降解。     

The influence of various degrees of confinement and supervision on the incidence of dystokia and stillbirths in Hereford heifers

Confinement of Hereford heifers in a pen during parturition resulted in a marked increase in the incidence of dystokia and stillbirths when cqmpared with animals left to calve in either the paddock or a large yard. The continuous presence of an observer during second-stage labour also was associated with an increase in both calving problems and assisted parturitions among penned cattle but the stillbirth rate was reduced in those animals undergoing a dystokia.

In most cases, death of the foetus or new-born calf was due to a difficult delivery. The cause of death, however, was not determined for about one-third of all stillborn foetuses found in the paddock or yard. In a few instances, the loss of new-born animals in the paddock was due to prematurity whereas in the pen, death occasionally occurred through misadventure or from suffocation by the amnion.

An increase in the degree of confinement and supervision of parturient animals was also accompanied by an alteration in the main types of calving problems encountered. Stillbirths of unknown aetiology and dystokia due to a posteriorly presented foetus constituted the 2 most important problems seen under paddock conditions. Cattle maintained in a yard prior to and during parturition were found to suffer most frequently from retained foetal membranes and dystokia involving a posteriorly presented foetus. Confinement of cattle in a pen usually resulted in a dystokia caused by vulval constriction.     

Effect of excess dietary sodium, potassium, calcium and phosphorus on excreta moisture of laying hens

1. Four experiments were conducted to investigate the effects of dietary concentrations of sodium, potassium, calcium or phosphate on the water intake and excreta moisture of laying hens. A fifth experiment examined the effect on these variables of increasing amounts of 2 different sodium salts (chloride or bicarbonate) and the interactions with 2 levels of dietary phosphorus. 2. All experiments involved individually caged laying hens fed on diets varying in 1 or 2 minerals in replacement for washed sand. The experimental diets contained mineral concentrations that either met or exceeded the expected requirement of the hens. The diets were given for a 7 or 8 d feeding period and food and water intakes were measured and excreta were collected for the last 48 h of each feeding period. These data were corrected for evaporative water loss to the environment during the collection period. 3. Increasing dietary concentrations of sodium, potassium or phosphorus gave linear increases (P<0.001) in the water intake of the laying hens and linear increases (P<0.01) in the moisture content of their excreta. Each 1 g/kg increase in dietary mineral increased the moisture content of the excreta by 9.04 (+/- 1.57), 11.95 (+/- 2.02) and 5.59 (+/- 0.31) g/kg (+/- standard error) for sodium, potassium and phosphorus, respectively. Increasing concentrations of dietary calcium did not significantly affect the water intakes or excreta moisture levels of the laying hens. 4. The fifth experiment showed that, although there was a sodium x phosphorus interaction (P<0.05), the effects of the 2 mineral additions were approximately additive. There were no significant differences (P>0.05) in water intakes or excreta moisture contents due to the 2 different sodium salts (chloride or bicarbonate).     

不同水分吸附材料对象草青贮发酵品质及好氧稳定性的影响

象草收获时往往具有较高水分,单独青贮发酵品质不佳。为提高象草青贮品质,研究了不同水分吸附材料对象草青贮发酵品质和好氧稳定性的影响。处理设为对照、分别添加象草鲜重10%的米糠、小麦粉、干豆腐渣和麦麸。青贮60 d后分析发酵品质和好氧稳定性。结果表明:所有添加处理均比对照显著增加了青贮原材料的干物质(DM,P<0.01),降低了缓冲能(P<0.05);青贮后,所有添加处理均显著提高了乳酸含量(P<0.01)。添加小麦粉显著增加了丁酸(0.81%DM)和氨态氮(NH₃-N,14.40%TN)含量(P<0.05),而其他添加处理无显著影响(P>0.05),添加干豆腐渣的处理丁酸和氨态氮含量最低,分别只有0.04%DM和9.75%TN。添加小麦粉和干豆腐渣对青贮饲料好氧稳定性改善效果最佳。综合比较分析营养特性、青贮发酵品质和好氧稳定性,添加干豆腐渣的处理青贮效果最优。     

有机微量元素对生长猪生长性能及微量元素排出量的影响

选用96头平均体重为（19.13±1.18）kg生长猪,分为处理1组（高剂量无机微量元素组）、处理2组（高剂量有机元素组）、处理3组（低剂量无机元素组）、处理4组（高剂量有机元素组）,每个处理3个重复,每个重复8头仔猪,试验期50 d,研究有机微量元素对生长猪生长性能及微量元素排出量的影响力。结果表明：处理1、2、4组的日增重分别比处理3组提高5.83%、7.03%、7.70%,均显著高于处理3组（P＜0.05）,其他处理组之间的日增重差异不显著。处理1、2、4组的料重比分别比处理3组降低5.28%、6.79%、7.92%,均达差异显著（P＜0.05）,处理1、2、4组之间的料重比差异不显著,处理4组的料重比最低。处理1组和处理2组粪中铜、铁、锌、锰的排泄量差异均不显著,处理3组和处理4组粪中铜、铁、锌、锰的排泄量差异均不显著,处理3组和处理4组粪中铜、铁、锌、锰的排泄量比处理1组和处理2组显著降低（P＜0.05）。     

Effects of induced hypothyroidism on weight gains, lactation, and reproductive performance of primiparous Brahman cows.

Primiparous, spring-calving Brahman cows (BW = 425.0 +/- 13.8 kg, body condition score [BCS] = 5.0 +/- .2 units; SEM) were used to study the effects of thyroid manipulation on weight gain, milk production, and reproduction. Nine cows served as controls. Nine cows were induced to become hypothyroid by daily ingestion of 4 mg/kg BW of 6-n-propyl-2-thiouracil (PTU). Cows were stratified to treatment 1 d after calving based on season of birth, BW, BCS, calf sex, and calf sire. The treatment period lasted for 84 d and was followed by a 56-d posttreatment period. Cow BW, BCS, and calf weight were recorded twice weekly. Milk production was estimated at 14, 28, 56, 84, 98, 112, and 140 d after calving. Weekly blood samples were obtained for analysis of triiodothyronine (T3), thyroxine (T4), and progesterone (P4). Estrus was monitored twice daily with the aid of a fertile bull equipped with a chin ball marker. Hypothyroidism was effectively induced in all PTU cows during the treatment period. The PTU cows gained more (P = .002) weight (54.6 +/- 7.6 kg) and tended (P = .06) to increase body condition (.61 +/- .17 units) more than control cows (15.7 +/- 7.6 kg; .11 +/- .17 units) during the treatment period. Control calves gained at a faster rate (.85 +/- .04 kg/d; P < .01) than PTU calves (.70 +/- .04 kg/d) during the treatment period. Milk production was lower (P < .05) in PTU cows on d 56 and 84. During posttreatment all trends were reversed, and BW, BCS, calf weight, and milk production were similar between the two groups by d 140. Reproductive performance was not affected by induction of hypothyroidism. In conclusion, induction of hypothyroidism was successful in increasing cow weight and BCS gains and suppressing milk production during the treatment period, but these changes were not successful in improving reproductive performance of primiparous Brahman cows.     

Effects of experimentally induced Isospora suis infection on morbidity, mortality, and weight gains in nursing pigs

Forty-nine pigs from 6 litters were inoculated at 3 days of age with 300,000 sporulated oocysts of Isospora suis to determine the effects of neonatal coccidiosis on morbidity, mortality, and weight gain in nursing pigs. Fifty-one control pigs from 6 litters were not inoculated. Three to 5 days after inoculation, the inoculated pigs developed a nonhemorrhagic diarrhea, generally lasting 6 to 10 days, that lead to visible dehydration, loss of condition, and 20.4% mortality. Control pigs did not die or develop coccidiosis during the 3-week study and had significantly (P less than 0.05) greater body weights at 7, 14, and 21 days of age than did the inoculated pigs.     

Performance by feedlot steers and heifers: daily gain, mature body weight, dry matter intake, and dietary energetics

Performance, DMI, diet composition, and slaughter data from 9,683 pens of steers and 5,009 pens of heifers that were fed high-concentrate diets for 90 d or more were obtained from 15 feedlots from the western United States and Canada. The data set included pen means for more than 3.1 million cattle fed between 1998 and 2004. Performance measurements assessed included ADG, DMI, dietary NE, shrunk initial weight (SIW), and shrunk final weight. Mature final weight (MFW) for cattle in each pen was estimated based on regression of slaughter weight against SIW and ADG across all pens. Equations were developed to standardize performance projections (ADG, MFW, and break-even values) and analyze feedlot cattle close-outs. Generally, as diet NE concentration increased, DMI was decreased but G:F, dressing percentage, and yield grade all increased. Pens of cattle with greater SIW had greater ADG, DMI, and shrunk final weight but a lower G:F and dressing percentage. Dressing percentage and yield grade were correlated positively. Equations of the NRC relating gain to NE intake explained 85 and 80% of the variation in DMI of steers and heifers, respectively, with mean ratios of predicted to observed DMI (DMIratio) at 1.000 +/- 0.0506 and 0.974 +/- 0.0490. However, a significant (P < 0.001) bias in the NRC estimate of DMI was detected (r(2) = 0.10 and 0.05, for steers and heifers) between the DMIratio and ADG in which DMIratio increased as ADG increased. This was due to inherent confounding of ADG and MFW in the original NE equation of Lofgreen and Garrett. Based on iterative optimization to minimize the difference between expected and observed DMI, revised equations for retained energy (RE, Mcal/kg) were developed for steers and for heifers: RE(steer) = 0.0606 x (LW x 478/MFW(steer))(0.75)ADG(0.905); RE(heifer) = 0.0618 x (LW x 478/MFW(heifer))(0.75)ADG(0.905), where LW = mean shrunk live weight. The revised equations decreased the SD of the DMIratio by 5.4% (from 0.0496 to 0.0469) and eliminated the bias in DMIratio that was related to ADG (r(2) = 0.0006). The similarity between the 2 equations derived for steers and for heifers for estimation of RE from ADG supports the concept that scaling by MFW accounts for energy utilization differences between sexes.     

The effect of dietary yeast and protected methionine on performance and trace minerals status of growing Awassi lambs

Eighteen growing Awassi lambs were used in this study to determine the effect of supplementing two levels of yeast and methionine (cyc-methionine) on the trace elements bioavailability, growth rate, and general performance. The lambs were divided to three groups. The dietary treatments were the control diet (C), control diet plus 2 g cyc-methionine/lamb/day (T₁) and control diet plus 4 g cyc-methionine/lamb/day (T₂).

Lambs fed 2 g/day of cyc-methionine (T₁) showed a significantly higher (P < 0.05) copper, zinc, and cobalt concentrations in liver and meat tissues, but not the same trend in kidney. No significant (P > 0.05) effect of time and time × treatment interaction on copper, zinc, cobalt, and manganese concentrations in blood serum, but cobalt and manganese concentration showed significant (P < 0.05) change by time. Moreover, a significantly (P < 0.05) higher total body gain, average daily gain, dressing percentage, and lower feed conversion were detected in lambs from T₁ compared with the control and T₂ groups.

Feeding 2 g of cyc-methionine to growing lambs increased the net profit by $6.017/lamb and only $3.52/lamb fed 4 g cyc-methionine/day when compared with the control group.

In conclusion, feeding growing Awassi lambs yeast and methionine in a form of cyc-methionine, with a low level of 2 g/day, improve the bioavailability of copper, zinc, and cobalt by growing lambs and their growth performance.     

Effects of defaunation and dietary coconut oil distillate on fermentation,digesta kinetics and methane production of Brahman heifers

A 2 × 2 factorial experiment was conducted to assess the effects of presence or absence of rumen protozoa and of dietary coconut oil distillate (COD) supplementation on rumen fermentation characteristics, digesta kinetics and methane production in Brahman heifers. Twelve Brahman heifers were selected to defaunate, with 6 being subsequently refaunated. After defaunation and refaunation, heifers were randomly allocated to COD supplement or no supplement treatments while fed an oaten chaff‐based diet. Methane production (MP; 94.17 v 104.72 g CH₄/d) and methane yield [MY; 19.45 v 21.64 g CH₄/kg dry matter intake (DMI)] were reduced in defaunated heifers compared with refaunated heifers when measured at 5 weeks after refaunation treatment (p < 0.01). Supplement of COD similarly reduced MP and MY (89.36 v 109.53 g/d and 18.46 v 22.63 g/kg DMI, respectively; p < 0.01), and there were no significant interactions of defaunation and COD effects on rumen fermentation or methane emissions. Concentration of total volatile fatty acid (VFA) and molar proportions of acetate, propionate and butyrate was not affected by defaunation or by COD. Microbial crude protein (MCP; g/d) outflow was increased by defaunation (p < 0.01) in the absence of COD but was unaffected by defaunation in COD‐supplemented heifers. There was a tendency towards a greater average daily gain (ADG) in defaunated heifers (p = 0.09), but COD did not increase ADG (p > 0.05). The results confirmed that defaunation and COD independently reduced enteric MP even though the reduced emissions were achieved without altering rumen fermentation VFA levels or gut digesta kinetics.     

饲粮钙磷水平对蛋鸡血清生化指标和血浆矿物质含量的影响

血液中的几种血清蛋白、碱性磷酸酶活性及矿物质含量同蛋鸡骨骼的代谢和蛋壳的形成相关。饲粮中钙、磷水平直接影响血液生化指标和矿物质含量 ,进而影响骨骼代谢和蛋壳形成。本试验旨在以不同的钙、磷水平饲粮饲喂 2 0周龄的蛋鸡 ,测定其血液生化指标和矿物质含量的变化 ,分析其原因 ,为蛋鸡饲粮适宜钙、磷水平的研究积累数据。1　材料与方法1 1　动物与饲粮　从北京华都集团蛋鸡场购进30 0只健康 1 8周龄商品代北京红鸡 ,预饲两周后按体重随机分为 1 0组 ,每组 30只 ,分 6个重复单元饲养 ,每单元 5只鸡饲养于 2个相邻的镀塑蛋鸡笼内。试验…