Effect of fat supplementation and wheat pasture maturity on forage intake and digestion characteristics of steers grazing wheat pasture

Nine ruminally cannulated mixed-breed steers were used in a split-plot design to evaluate effects of fat supplementation and forage maturity on intake, digestibility, and ruminal fermentation. Treatment was the main plot, and stage of forage maturity was the subplot. Treatments were supplements containing mineral pack (M) offered at 114 g/d; M plus fiber as soybean hulls-wheat middlings (MF) offered at 0.50% BW; and MF plus tallow (MFT) offered at 0.625% BW. Stages of wheat maturity were mid-March (MAR) and early April (APR). Steers grazed in a single wheat pasture with supplements offered individually at 0700 h daily. There were supplement type x forage maturity interactions (P < 0.05) for forage OM, CP, and NDF intakes. During MAR, forage OM, CP, and NDF intakes were not affected (P > 0.05) by supplementation. During APR, forage OM, CP, and NDF intakes differed (MF = M > MFT, P < 0.05). There was also supplement type x forage maturity interaction (P = 0.04) for forage OM digestibility. The OM digestibility differed during MAR (M = MF > MFT, P < 0.05) and during APR (MF > M > MFT, P < 0.05). Crude protein digestibility was affected by supplement type (M > MF > MFT, P < 0.05) and stage of forage maturity (MAR > APR, P < 0.01). Rates of DM and NDF ruminal disappearance were not affected (P > 0.05) by supplement or forage maturity. Supplementation increased (P < 0.05) ruminal propionate concentration (19.7, 21.4, and 25.1 +/- 0.49 mol/100 mol for M, MF, and MFT, respectively). Tallow can be used in supplements for cattle grazing wheat pasture to increase energy intake without negatively affecting forage intake or ruminal fermentation, particularly if used in the early stage of wheat maturity.     

Utilization of dried distillers grains for developing beef heifers

A 2-yr study was conducted at 2 locations to determine if supplementing beef heifers with dried distillers grains (DDG) as an energy source affected growth or reproduction. Spring-born crossbred heifers (n = 316) were blocked by age or sire and age and assigned randomly to DDG or control (dried corn gluten feed, whole corn germ, urea) supplement. Heifers received prairie hay in amounts sufficient for ad libitum intake and 0.59% of BW DDG or 0.78% of BW control supplement (DM basis). Supplements were formulated to be isocaloric, but protein degradability differed. Supplemental undegradable intake protein intake from DDG averaged 267 g/animal daily and reached 318 g/animal daily; control supplemental undegradable intake protein intake averaged 90 g/animal daily and peaked at 107 g/animal daily. Initial pubertal status was determined by 2 blood samples collected 10 d apart, and monthly BW were collected from November through January; then biweekly BW and blood samples were collected from February until May yearly. Heifers were synchronized with 2 injections of PGF2alpha 14 d apart; estrus was detected and heifers were artificially inseminated for 5 d and placed with bulls 10 d later. Conception and pregnancy rates were determined via transrectal ultrasonography. Initial age, BW, and BCS did not differ (P > 0.92) for control and DDG heifers. Final BW, ADG, and final BCS also were not affected (P > 0.31) by supplementation. Estimated age and BW at puberty did not differ (P > 0.23) between treatments, and the proportions of pubertal heifers did not differ at the initiation of the experiment (P > 0.82), at the beginning of the 14-d sampling intervals, or before synchronization. Estrus synchronization rate (75.9%), time of estrus, and overall pregnancy rate (89.5%) were not affected (P > 0.14) by treatment. However, a greater proportion (P = 0.008) of DDG than control heifers conceived to AI (75.0 vs. 52.9%), resulting in greater (P = 0.07) AI pregnancy rates for DDG heifers (57.0 vs. 40.1%). Body weight or BCS at pregnancy diagnosis did not differ (P > 0.52) between DDG and control heifers. Supplementing beef heifers with DDG during development did not affect age at puberty but improved AI conception and pregnancy rates compared with an isocaloric control supplement.     

Effects of dried distillers grains and equivalent undegradable intake protein or ether extract on performance and forage intake of heifers grazing smooth bromegrass pastures

Crossbred heifers (n = 120; BW = 368 kg, SD = 39 kg) were used to determine effects of dried distillers grains (DDG) and relative contributions of undegradable intake protein (UIP) and fat (ether extract, EE) in DDG on ADG and forage intake (FI). Heifers rotationally grazed six 3.5-ha, smooth bromegrass paddocks (IVDMD = 65.7%, CP = 20.8%, UIP = 2.17%, DM basis). Heifers were blocked by previous ADG and allotted to treatments in a 3 x 3 + 1 factorial design. Factors were source and level of supplementation. Supplements were as follows: 1) DDG (UIP = 15.8%, EE = 9.67%), 2) corn gluten meal (CGM; UIP = 31.6%, EE = 0.83%), or 3) corn oil (OIL; UIP = 0.74%, EE = 19.3%). Amounts of DDG were 750, 1,500, or 2,250 g/d, whereas amounts of CGM and OIL were 375, 750, or 1,125 g/ d. Supplements containing CGM and OIL were fed in amounts that provided UIP and EE, respectively, equivalent to those of the DDG. Contrasts of interest were DDG vs. CGM and DDG vs. OIL. Control heifers were fed 250 g/d of a supplement containing corn bran and molasses (UIP = 0.92%, EE = 1.13%). Heifers were supplemented individually. Treatments were separated by regressing the response variables on grams of nutrient (DM, UIP, or EE) intake per kilogram of BW, because not all heifers consumed their allotment of supplement. Supplemental DDG resulted in a linear increase in ADG (P < 0.01), whereas CGM tended to increase ADG (P = 0.14) but at a rate that was 39% of that for DDG, representing a response to MP. Supplementation of OIL did not affect ADG (P = 0.25) and tended to result in ADG less than that of DDG (P = 0.09). Supplementation with DDG had no effect (P = 0.63) on FI when predicted by the use of chromic oxide but tended (P = 0.07) to decrease FI when it was predicted from ADG using NE equations. Despite the differences between methods in the significance of the effect of DDG, the rates of substitution agreed (-0.50 and -0.45 for chromic oxide and NE equations, respectively), suggesting that the chromic oxide method was less sensitive in assessing FI. Supplementation with CGM decreased FI (P < 0.01), but FI for CGM did not differ from that of DDG when the chromic oxide method was used (P = 0.19). Corn oil had no effect on FI (P = 0.42). Increased ADG and decreased FI observed from DDG supplementation is not independently explained by UIP or EE contained in DDG.     

Supplementation of dried distillers grains with solubles to beef cows consuming low-quality forage during late gestation and early lactation

Three experiments were conducted to evaluate supplementation of dried distillers grains with solubles (DGS) to spring-calving beef cows (n = 120; 541 kg of initial BW; 5.1 initial BCS) consuming low-quality forage during late gestation and early lactation. Supplemental treatments included (DM basis) 1) 0.77 kg/d DGS (DGSL); 2) 1.54 kg/d DGS (DGSI); 3) 2.31 kg/d DGS (DGSH); 4) 1.54 kg/d of a blend of 49% wheat middlings and 51% cottonseed meal (POS); and 5) 0.23 kg/d of a cottonseed hull-based pellet (NEG). Feeding rate and CP intake were similar for DGSI and POS. In Exp. 1, cows were individually fed 3 d/wk until calving and 4 d/wk during lactation; total supplementation period was 119 d, encompassing 106 d of gestation and 13 d of lactation. Tall-grass prairie hay (5.6% CP, 50% TDN, 73% NDF; DM basis) was fed for ad libitum intake throughout the supplementation period. Change in cow BW and BCS during gestation was similar for DGSI and POS (-5.0 kg, P = 0.61 and -0.13, P = 0.25, respectively) and linearly increased with increasing DGS level (P < 0.01). Likewise, during the 119-d supplementation period, BW and BCS change were similar for DGSI and POS (-72 kg, P = 0.22 and -0.60, P = 0.10) and increased linearly with respect to increasing DGS (P < 0.01). The percentage of cows exhibiting luteal activity at the beginning of breeding season (56%, P = 0.31), AI conception rate (57%, P = 0.62), or pregnancy rate at weaning (88%, P = 0.74) were not influenced by supplementation. In Exp. 2, 30 cows from a separate herd were used to evaluate the effect of DGS on hay intake and digestion. Supplementation improved all digestibility measures compared with NEG. Hay intake was not influenced by DGS (P > 0.10); digestibility of NDF, ADF, CP, and fat linearly increased with increasing DGS. In Exp. 3, milk production and composition were determined for cows (n = 16/treatment) of similar days postpartum from Exp. 1. Daily milk production was not influenced by supplementation (6.3 kg/d, P = 0.25). Milk fat (2.1%) and lactose (5.0%) were not different (P > 0.10). Milk protein linearly increased as DGS increased (P < 0.05) and was greater for DGSI compared with POS. Similar cow performance was achieved when cows were fed DGS at the same rate and level of CP as a traditional cottonseed meal-based supplement. Increasing amounts of DGS did not negatively influence forage intake or diet digestibility.     

Effect of distillers grains or corn supplementation frequency on forage intake and digestibility

Ten ruminally cannulated heifers (BW = 416 kg; SD = 24) were used to test the effect of the form and frequency of supplemental energy on forage DMI and digestibility. Five treatments were arranged in a replicated, 5 x 4 Latin rectangle (n = 8), and included no supplement (control), dry-rolled corn (DRC) fed daily, DRC fed on alternate days (DRC-A), dried distillers grains plus solubles (DDGS) fed daily, and DDGS fed on alternate days (DDGS-A). Supplements fed daily were fed at 0.40% of BW, whereas alternate day-fed supplements were fed at 0.80% of BW every other day. Chopped grass hay (8.2% CP) was fed to allow ad libitum DMI, and the intake pattern was measured. Control heifers had greater (P < 0.01) hay DMI than supplemented heifers (1.88 vs. 1.66% of BW daily, respectively), although total DMI was lower (P < 0.01) for control. Hay DMI did not differ (P = 0.45) between DRC and DDGS, and tended to be lower (P = 0.08) by heifers on DDGS-A and DRC-A than by heifers supplemented daily. Hay intake was lower (P < 0.01) on supplementation days for DDGS-A and DRC-A than on nonsupplemented days. Heifers in alternate-day treatments had fewer (P < 0.01) and larger (P < 0.01) meals and spent less (P < 0.01) time eating than those supplemented daily. Average rumen pH was greater (P = 0.05) for control than supplemented heifers (6.30 vs. 6.19). Control heifers had greater (P = 0.04) rates and extents of NDF disappearance than supplemented heifers. Rate of hay NDF disappearance was lower (P = 0.02) for DRC than for DDGS. Supplementation decreased hay DMI and changed digestion kinetics. Supplementation frequency affected amount and pattern of DMI. Rate of hay NDF disappearance was greater for DDGS than DRC.     

玉米DDGS在生长育肥猪生产中的应用研究进展

文章综述了玉米DDGS对生长育肥猪的营养价值,不同添加量对生长育肥猪生产性能的影响,以及玉米DDGS中高含量多不饱和脂肪酸对猪胴体脂肪酸组成以及碘值的影响。     

Comparison of wheat or corn dried distillers grains with solubles on rumen fermentation and nutrient digestibility by feedlot heifers

A 5 × 5 Latin square design trial was conducted to evaluate rumen fermentation and apparent nutrient digestibility in 5 rumen-cannulated heifers (420 ± 6 kg) fed a barley-based finishing diet supplemented with 20 or 40% wheat or corn dried distillers grains with solubles (DDGS). The composition of the control diet was 88.7% rolled barley grain, 5.5% supplement, and 5.8% barley silage (DM basis). Increasing the quantity of corn DDGS in the ration resulted in a quadratic decrease in DMI (P = 0.04) and OM intake (P = 0.05). Rumen pH, pH duration, and area under rumen pH thresholds of 5.8 or 5.5 were not affected (P > 0.05) by treatment. Inclusion of wheat DDGS resulted in a quadratic increase (P = 0.05) in pH area below the cutoff value of 5.2, with the most pronounced effect at 20% inclusion. Wheat DDGS linearly increased (P = 0.01) rumen NH(3)-N concentrations. Increasing the inclusion rate of wheat and corn DDGS resulted in quadratic (P = 0.05) and linear (P = 0.04) decreases in rumen propionate, whereas butyrate increased quadratically (P < 0.01) and linearly (P < 0.01), respectively. Feeding wheat DDGS linearly decreased (P < 0.01) DM and OM digestibility values. Inclusion of corn DDGS increased the digestibility values of ether extract (P = 0.05; quadratic response) and CP (P < 0.01; linear response). Neutral detergent fiber digestibility increased in a linear fashion (P = 0.01) as both wheat and corn DDGS inclusion increased, whereas ADF digestibility increased linearly (P = 0.03) for wheat and quadratically (P = 0.02) for corn DDGS. Increased inclusion of wheat DDGS resulted in a linear decrease in GE digestibility (P = 0.01), whereas increasing corn DDGS inclusion linearly increased (P < 0.01) the DE content of the diet. Feeding both wheat and corn DDGS linearly increased (P = 0.01) the excretion of N and P. In summary, replacement of barley grain with up to 40% wheat or corn DDGS did not mitigate rumen pH conditions associated with mild to moderate acidosis in heifers fed a barley-based finishing diet. Supplementing corn DDGS increased nutrient digestibility of all nutrients and, as a result, led to greater DE content. Supplementation of wheat DDGS reduced DM and OM digestibility values, with no effect on DE content. Increased N and P excretion by heifers fed DDGS at 20 or 40% of dietary DM presents a challenge for cattle feeders with respect to nutrient management.     

Effects of distillers dried grains with solubles and mineral sources on gaseous emissions

Distillers dried grains with solubles (DDGS), an important ethanol industry co-product, has been used as a high-protein feed in poultry production. Limited studies exist on their effect on air emissions, however. In the current study, 4 diets (2 × 2 factorial design: 0 or 20% DDGS + inorganic or organic mineral sources) were fed to Hy-line W36 hens from 50 to 53 wk of age and the effects of DDGS level and mineral sources on air emissions were monitored continuously for a 23-d period in environmentally controlled chambers. The NH₃, H₂ S, CH₄, nonmethane hydrocarbons, N₂ O, CO₂, and CO₂-equivalent emissions ranged from 0.51 to 0.64 g/day-hen, 0.71 to 0.84 mg/day-hen, 33.9 to 46.0 mg/day-hen, 54.1 to 60.0 mg/day-hen, 66.0 g to 72.2 g/day-hen, and 83.1 to 92.1 g/day-hen, respectively. Feeding DDGS to laying hens resulted in 14% decreased NH₃ emissions but a 19% increase in CH₄ emissions without affecting other gaseous emissions. More than 30% of N, 80% of P, 80% of K, and 50% of Ca was retained in the manure. In conclusion, feeding laying hens a diet containing 20% DDGS may be beneficial for the environment. Substitution for organic trace minerals did not affect hen performance or air emissions.     

日粮添加干玉米酒糟对泌乳奶牛干物质采食量、泌乳性能和瘤胃发酵的影响

文章旨在研究日粮中添加不同比例的干玉米酒糟对泌乳奶牛干物质采食量、泌乳性能和瘤胃发酵的影响。试验选择45头健康的中国荷斯坦奶牛,按照胎次、泌乳天数和产奶量进行区组设计,随机分配到3个处理组中,每组15头牛。对照组奶牛饲喂以玉米和豆粕为基础的日粮,不含有干玉米酒糟,试验1组和试验2组奶牛饲喂的日粮均以干玉米酒糟替代部分玉米和豆粕,替代比例分别为10%和20%(干物质基础)。预试期为2周,正试期为10周。试验结果表明,日粮添加干玉米酒糟显著提高了泌乳奶牛干物质采食量(P<0.05),而不同干玉米酒糟添加比例对奶牛的干物质采食量无显著影响(P>0.05)。日粮添加干玉米酒糟显著提高了泌乳奶牛的产奶量,且呈剂量依赖效应(P<0.05)。日粮添加干玉米酒糟对乳成分无显著影响(P>0.05),但由于产奶量的增加显著增加了乳中营养成分含量(P<0.05)。日粮添加干玉米酒糟改变了瘤胃发酵模式,降低了瘤胃液乙酸摩尔比值(P<0.05),增加了丙酸和丁酸摩尔比值(P<0.05),降低了瘤胃液NH3-N浓度。因此,可以使用干玉米酒糟替代部分玉米和豆粕来配合奶牛日粮,本试验中以20%的添加量较为合适。     

DDGS对鸡肉品质影响的研究

随机设置2个处理组(对照组和添加8%DDGS的试验组,n=144)来评估在肉鸡日粮中添加DDGS对鸡胸肉和鸡腿肉质量的影响。首先利用电击瞬间致昏动物,然后作放血、浸烫、打毛等处理。肉鸡死亡4h之后将胸肉和腿肉从鸡胴体上在低温条件下剥离。右侧鸡胸肉用来测定肉色、pH值、蒸煮损失、剪切力值,左侧胸肉用于感官评定;腿肉用于评估总胆汁酸(TBA)和脂肪酸组成。结果显示:添加了DDGS的试验组在肉色、pH值、蒸煮损失、剪切力值上与对照组差异不显著(P0.05)。另外,对照组和试验组在鸡肉质地上没有显著差异(P0.05),但对照组的鸡肉风味更容易被多数人所接受。一般喜欢和非常喜欢鸡肉的消费者不在这两个处理组之内,两组的试验成员属于一般可接受鸡肉的消费者。另外在感官评定的试验中,消费者对添加DDGS和对照组的鸡肉评价没有明显差异(P0.5),各组间的脂肪酸结构变化不大(P0.05),但添加DDGS处理组的鸡肉在亚油酸、多不饱和脂肪酸含量上和对照组有很大差异(P0.05),这表明试验组的鸡肉更容易被氧化。总的来说,这两种喂养方式都可以生产出高质量的鸡胸肉和鸡腿肉。     

猪日粮中干酒糟及其可溶物的价值测定

客户经常向我们咨询,他们应该如何评估猪日粮中干酒糟及其可溶物(Dried Distillers Grains with Solubles,DDGS)的价值。虽然这似乎是一个简单的问题,但实际上我们需要考虑数个因素才能准确地确定其价值。     

Vitamin E supplementation in beef finishing diets containing 35% wet distillers grains with solubles: feedlot performance and carcass characteristics

Supplementation of vitamin E has indications for improving cattle health, performance, and retail characteristics when included in grain-based diets. This experiment was conducted to determine performance and carcass characteristics of steers fed diets containing wet distillers grains with solubles (WDGS) and supplemented with vitamin E. Steers of mixed Bos indicus and Bos taurus breeding (n = 199; BW = 363 ± 32 kg) were blocked by BW and assigned to 1 of 4 supplemental vitamin E (VITE) treatments [0 (control), 125, 250, and 500 IU·steer(-1)·d(-1)], which were fed for the last 97 d of the feeding period. Two blocks were on feed 129 d, and 3 blocks were fed for 150 d. Steers were fed a dry-rolled corn-based finishing diet with 35% WDGS (DM basis). Individual BW were measured initially, the initial day of vitamin E supplementation, and the day of slaughter. Carcass weights were collected at slaughter, and carcass data were collected after a 36-h chill. Body weight and ADG were not affected by VITE (P ≥ 0.34). There was a tendency for a linear (P = 0.08) increase in carcass-adjusted BW with increasing VITE. Use of carcass-adjusted final BW resulted in a linear increase (P = 0.04) in ADG with increasing VITE. Pre-vitamin E and vitamin E feeding period DMI were not affected (P ≥ 0.24) by VITE, but there was a tendency (P = 0.08) for a linear increase in overall DMI with increasing VITE. No difference (P ≥ 0.29) occurred in G:F measures using BW gains, but G:F using carcass-adjusted BW gains resulted in a trend (P = 0.11) for G:F to increase linearly with increasing VITE. Hot carcass weights tended (P = 0.08) to increase linearly with increasing dietary vitamin E. Vitamin E supplementation resulted in no effects (P ≥ 0.13) on measured carcass characteristics. Calculated yield grades (YG) were also not affected (P ≥ 0.37). However, the distribution of calculated YG resulted in a quadratic effect (P = 0.02) for YG 3 with the control and 500 VITE being greater than the 2 intermediate amounts. However, the percentage of carcasses grading YG 3 or less were not affected by vitamin E supplementation (P = 0.64). No differences were observed in the distribution of quality grades based on marbling scores (P ≥ 0.57). Data from this study suggest that vitamin E supplemented above basal requirements during the last 97 d of the feeding period in finishing diets containing 35% WDGS results in slight to no effect on animal performance or carcass characteristics.     

DDGS在猪日粮中的应用研究

<正>自20世纪70年代以来,大规模的酒精副产物DDGS被生产出来,这使得众多学者加大研究力度将其添加到动物日粮中(Wahlstrom等,1970;Smelski和Stothers,1972;Cromwell等,     

日粮添加酒糟对后备奶牛生长性能和营养物质消化率的影响

文章旨在研究不同比例的酒糟对后备奶牛生长性能和营养物质消化率的影响。试验选择日龄、体重和体况近似的健康荷斯坦育成牛30头,按照日龄和体重进行分组设计,将其随机分为3组,每组10头。对照组饲粮精料成分为玉米和大豆榨油副产物,试验组Ⅰ饲粮精料成分中添加15%的酒糟,试验组Ⅱ饲粮精料成分中添加30%的酒糟。预试期为2周,正试期为24周。试验期间限饲。试验期间每天记录育成牛的采食量。分别于试验开始和结束时测定育成牛的生长性能指标。于正试期第24周进行消化试验,测定营养物质消化率。试验结果表明,日粮中添加不同比例的酒糟替代玉米和大豆榨油副产物对育成牛干物质采食量和生长性能无显著影响(P>0.05)。日粮中添加不同比例的酒糟替代玉米和大豆榨油副产物对育成牛日粮干物质和有机物的表观消化率无显著影响(P>0.05),但显著提高了粗蛋白质和纤维的表观消化率(P<0.05)。30%酒糟添加组育成牛日粮粗蛋白质表观消化率分别比15%酒糟添加组和对照组育成牛高4.55%和6.82%(P<0.05),而15%酒糟添加组和对照组育成牛日粮粗蛋白质表观消化率差异不显著(P>0.05)。30%酒糟添加组育成牛日粮中性洗涤纤维表观消化率分别比15%酒糟添加组和对照组育成牛高6.70%和7.44%(P<0.05),而15%酒糟添加组和对照组育成牛日粮中性洗涤纤维表观消化率差异不显著(P>0.05)。30%酒糟添加组育成牛日粮酸性洗涤纤维表观消化率分别比15%酒糟添加组和对照组育成牛高6.64%和8.04%(P<0.05),而15%酒糟添加组和对照组育成牛日粮酸性洗涤纤维表观消化率差异不显著(P>0.05)。因此,育成牛日粮中可以添加酒糟替代部分玉米和大豆榨油副产物,本试验中最高添加比例为30%。     

Supplemental soybean oil or corn for beef heifers grazing summer pasture: effects on forage intake, ruminal fermentation, and site and extent of digestion.

Nine Angus x Gelbvieh heifers (average BW = 347 +/- 2.8 kg) with ruminal and duodenal cannulas were used in a split-plot designed experiment to determine the effects of soybean oil or corn supplementation on intake, OM, NDF, and N digestibility. Beginning June 8, 1998, heifers continually grazed a 6.5-ha predominantly bromegrass pasture and received one of three treatments: no supplementation (Control); daily supplementation of cracked corn (Corn) at 0.345% of BW; or daily supplementation (0.3% of BW) of a supplement containing cracked corn, corn gluten meal, and soybean oil (12.5% of supplemental DM; Oil). Soybean oil replaced corn on a TDN basis and corn gluten meal was included to provide equal quantities of supplemental TDN and N. Three 23-d periods consisted of 14 d of adaptation followed by 9 d of sample collections. Treatment and sampling period effects were evaluated using orthogonal contrasts. Other than crude fat being greater (P = 0.01) for supplemented heifers, chemical and nutrient composition of masticate samples collected via ruminal evacuation did not differ (P = 0.23 to 0.56) among treatments. Masticate NDF and ADF increased quadratically (P < or = 0.003) and N decreased linearly (P = 0.0001) as the grazing season progressed. Supplementation did not influence (P = 0.37 to 0.83) forage OM intake, total and lower tract OM digestibility, ruminal and total tract NDF digestibility, or total ruminal VFA; however, supplemented heifers had lower ruminal molar proportions of acetate (P = 0.01), higher ruminal molar proportions of butyrate (P = 0.007), and greater quantities of OM digested in the rumen (P = 0.10) and total tract (P = 0.02). As the grazing season progressed, total tract OM and N and ruminal NH3 concentrations and NDF digestibility decreased quadratically (P < or = 0.04). Microbial N flow (P = 0.09) and efficiency (P = 0.04) and postruminal N disappearance (P = 0.02) were greater for Control heifers and declined linearly (P < or = 0.02) as the grazing season advanced. Depressed microbial N flow seemed to be more pronounced for Oil than for the Corn treatment. Although total digestible OM intake increased with supplementation, metabolizable protein supply was reduced in supplemented heifers. Therefore, feeding low levels of supplemental grain with or without soybean oil is an effective strategy to increase dietary energy for cattle grazing high-quality forages, but consideration should be given to reduced supply of metabolizable protein.     

Effects of increasing dried distillers grains with solubles on performance, carcass characteristics, and digestibility of feedlot lambs

The objectives of this study were to determine the effects of 0, 20, 40, or 60% dietary dried distillers grains with solubles (DDGS) on 1) growing lamb performance, carcass characteristics, and tissue minerals, and 2) nutrient digestibility and retention in growing lambs. In Exp. 1, ninety-six lambs were blocked by sex (ewes, n = 48; wethers, n = 48) and BW, housed in 24 pens (4 lambs per pen), and used in a 92-d feedlot trial (initial BW = 26.4 ± 9.3 kg). Lambs were fed 1 of 4 dietary treatments 1) 0% DDGS, 2) 20% DDGS, 3) 40% DDGS, or 4) 60% DDGS. The DDGS replaced primarily corn, and diets were fed as a complete pellet. There was a quadratic effect of DDGS inclusion on ADG; lambs fed the 20% DDGS diet had the greatest (P = 0.04) gains at 0.358 kg/d. This effect on ADG led to a quadratic (P = 0.03) effect of DDGS on final BW. Increasing dietary DDGS did not affect (P > 0.13) DMI and resulted in a linear (P = 0.02) decrease in G:F. In the liver, S increased linearly (P = 0.05), whereas Cu decreased linearly (P < 0.01) with increasing dietary DDGS; other liver minerals were not affected (P > 0.05). Carcass backfat, yield grade, and marbling score were not affected (P > 0.05) by dietary DDGS. In Exp. 2, twenty-four lambs (initial BW = 43.0 ± 4.4 kg) were used in a metabolism study. Lambs were adapted to the same diets described above for 17 d before a 5-d sampling period during which total feces and urine were collected. Apparent digestibility of dietary DM decreased linearly (P < 0.01) with increasing dietary inclusion of DDGS. Digestibility of fat followed a similar pattern, whereas N, S, and P absorption increased linearly (P < 0.03) with increasing dietary DDGS. The digestibility of NDF was not affected (P > 0.05) by dietary treatment. Apparent retentions (as a percentage of intake) of N, K, Mg, Cu, Fe, and Zn were not affected (P > 0.05) by dietary DDGS inclusion, whereas the retention of S and P decreased (P < 0.04). Daily urine output increased linearly (P < 0.01) and urine pH decreased linearly (P < 0.01) with increasing DDGS (urine pH was 7.46, 5.86, 5.52, and 5.32 for treatments 1 to 4, respectively). These data suggest urine is a major route for excretion of acid when high-S diets containing DDGS are fed. Increases in dietary DDGS resulted in decreased digestion of DM and fat, which may be partially responsible for decreased lamb feedlot performance for 40 and 60% dietary DDGS when compared with 20% DDGS.