氨化小麦秸在阉牛生长育肥期的利用与效益分析

选用24头乌珠穆沁品种生长期阉牛,进行连续90天的饲喂氨化与未氨化小麦秸的对比生长试验,结果表明。在阉牛生长育肥阶段,采用精料比例连续递进(40％→60％→80％)的饲养制度时,饲喂氨化麦秸较未氨化麦秸可使阉牛日粮干物质进食量(DMI)平均提高18％,日增重(ADG)平均提高34％,日粮精料转化效率(C/G)平均提高12.8％,每公斤增重的饲料费用(FC/G)平均降低0.16元.其中,在40％、60％和和80％精料比例下,饲喂氨化麦秸可使阉牛日粮DMI分别提高45.3％、19.1％和2.3％;ADG分别提高111.1％、39.1％和5.8％;C/G分别改进30.2％、11.4％和2.9％FC/G分别降低0.41、0.19和0.03元。在40％—80％精料比例范围内,给阉牛饲喂氨化秸可以提高动物的生产性能,但其提高幅度随日粮精料水平提高而下降。     

精料水平与秸秆氨化对绵羊瘤胃纤维降解的影响

采用6×6拉丁方设计方法,研究了日粮精料水平与秸秆氨化对绵羊瘤胃纤维降解的影响。以氨化与未氨化小麦秸样本瘤胃培养48小时的尼龙袋干物质消失率(ISDMD)作为瘤胃纤维降解程度的度量指标。对瘤胃 PH、VFA 与 NH_3—N浓度等瘤胃参数进行了测定。结果表明,随日粮精料水平的提高,绵羊瘤胃纤维降解程度下降。其中,精料水平由30％提高到50％没有明显下降(P>0.05),而精料水平由50％提高到70％显著下降(P<0.05)。在同一瘤胃环境中培养的氨化麦秸样本 ISDMD 总是明显高于未氨化麦秸样本。在相同精料水平下,饲喂氨化麦秸日粮的绵羊瘤胃纤维降解程度低于饲喂未氨化麦秸粮的动物。对瘤胃纤维降解与瘤胃参数变化的关系进行了讨论。     

日粮中尿素氨化稻草水平对体外培养发酵总产气量、氨态氮和pH值的影响

本试验旨在研究日粮中添加不同比例的氨化稻草及精组比例对体外发酵产气规律的影响。以2头安装有永久性瘤胃瘘管的西门塔尔牛作为瘤胃液供体,以未氨化、4%尿素和6%尿素氨化的稻草为粗饲料,分别与精料混合料配制成6种比例日粮,其中精料与粗饲料的比例为0∶100、20∶80、40∶60、60∶40、80∶20、100∶0。采用体外产气法测定各种日粮体外发酵的产气规律。结果表明:同一尿素氨化水平下,随着精料比例增加,产气量显著增加(P<0.05),并且精料∶粗料为100∶0组极显著高于0∶100组(P<0.01);不同尿素氨化水平下,精料∶粗料为40∶60时,4%尿素氨化组48 h产气量显著高于未氨化组(P<0.05),并且高于6%氨化组,而精料∶粗料为0∶100、20∶80、60∶40、80∶20、100∶0时,3种尿素氨化水平产气量之间差异不显著(P>0.05)。表明使用4%尿素对稻草进行氨化处理、日粮精料∶粗料为40∶60时,日粮的可消化性最好。     

半胱胺对藏绵羊断奶羔羊增重及饲料转化效率的影响

试验研究了半胱胺(Cs)对藏绵羊断奶羔羊增重、饲料转化效率的影响。将40只(公母各半)80日龄左右且体重平均为(16.00±0.31)kg的藏绵羊断奶羔羊随机分为2组(试验组和对照组),在日粮精料中添加300 mg/(kg·BW)的Cs,隔日添加1次,试验期42 d。分别于开始用药后的第0、7、14、21、28、35天称重,并记录各组所采食的精料量。试验结果表明,试验组精料中添加Cs使藏绵羊断奶羔羊35 d增重提高43.25%(P0.01),开始用药后的前7 d差异不显著,但8~35 d最为明显,以后随时间延长促生长效果逐渐减弱;精料/增重比下降43.33%。     

用氨化麦秸低精料育肥早胜牛试验

使用氨化麦秸配合基础日粮育肥早胜牛，比使用普通麦秸能增加采食量13.1％，提高日增重77.7%。单位增重可节约精饲料43.8%，降低饲料费用32.3％。以氨化秸杆作为粗饲料，每头牛日初混合精料2kg。说明，在我省广农区，充分利用农作物秸杆，实行低精料育肥肉牛是完全可行的。     

日粮中氨化稻草水平对体外培养发酵甲烷和挥发性脂肪酸产量的影响

本试验旨在研究日粮中不同氨化稻草水平对瘤胃甲烷(CH4)和挥发性脂肪酸(VFA)产量的影响。以2头安装有永久性瘤胃瘘管的成年西门塔尔牛作为瘤胃液供体,以未处理稻草、4%尿素氨化稻草和6%尿素氨化稻草为粗料,分别与精料混合料以6种比例配合日粮,其中精料与粗料的混合比例分别为0∶100、20∶80、40∶60、60∶40、80∶20、100∶0。应用Menke等(1979)的体外培养发酵技术进行培养发酵并测定日粮48 h的总产气量、CH4和VFA产量。结果表明:日粮精料/粗料为0∶100时,4%尿素氨化稻草组和6%尿素氨化稻草组总VFA(TVFA)产量显著高于未氨化稻草组(P<0.05);随着日粮精料比例增加,乙酸、丙酸和TVFA产量显著增加(P<0.05),乙酸/TVFA和乙酸/丙酸显著下降(P<0.05);当日粮精料/粗料为40∶60时,4%尿素氨化稻草组和6%尿素氨化稻草组48 h CH4产量显著高于未氨化稻草组(P<0.05),并且4%尿素氨化稻草组48 h总产气量显著高于未氨化稻草组(P<0.05),在一定程度上高于6%尿素氨化稻草组(P>0.05);随着日粮精料比例增加,CH4产量和总产气量显著增加(P<0.05);48 h总产气量和CH4产量的组合效应值最高的组为日粮精料/粗料40∶60的4%尿素氨化稻草组;各组48 h总产气量均产生正组合效应,4%尿素氨化稻草组中CH4/TVFA均产生负组合效应。由此可知,CH4产量与日粮精料/粗料和日粮中粗料的品质有关。当日粮精料/粗料为40∶60时,4%尿素氨化稻草组48 h总产气量和CH4产量最高,但CH4/TVFA最低。     

麦秸不同调制方法对肉牛育肥效果的比较分析

为了充分利用农作物秸秆资源发展草食家畜，降低饲料成本，在麻城市种群畜场利用氨化，微贮麦秸对舍饲条件下的西杂一代公牛进行育肥试验，试验结果表明，试验１组（微贮麦秸＋混合精料）平均日增重为１．１１６ｋｇ，试验Ⅱ组（氨化麦秸＋混合精料）平均日增重为１．０９２ｋｇ，对照组（麦秸＋混合精料）平均日增重为０．８１５ｋｇ，试验线平均增重与对照线比较差异极显著（Ｐ〈０．０１）。     

陕北白绒山羊断奶羔羊钙磷需要量的研究

旨在研究日粮中不同钙磷水平对陕北白绒山羊断奶羔羊生产性能、养分消化代谢的影响,为制订陕北白绒山羊钙磷需要量标准提供参考依据。试验选取36只((16.48±2.37)kg)日龄、体况相近的陕北白绒山羊断奶羔羊,采用2×2试验设计,随机分为4组,每组设3个重复,每个重复3只羊,分别饲喂不同钙磷水平的日粮,Ⅰ组(0.60%钙、0.45%磷)、Ⅱ组(0.60%钙、0.65%磷)、Ⅲ组(0.80%钙、0.45%磷)和Ⅳ组(0.80%钙、0.65%磷)。试验共65d。在试验第30天,从每个重复中随机挑选1只羊,共12只,分别放入单独的代谢笼中进行消化代谢试验。结果表明:1)日粮不同钙磷水平对陕北白绒山羊断奶羔羊的干物质采食量没有显著的影响(P0.05),高钙、高磷水平日粮能够显著的提高日增重(P0.05)。2)日粮不同钙水平显著影响陕北白绒山羊断奶羔羊的总能消化率和代谢率(P0.05)。3)日粮不同钙磷水平分别显著影响陕北白绒山羊断奶羔羊的进食钙、磷量,排泄钙、磷量,沉积钙、磷量(P0.05)。排泄钙、磷与进食钙、磷之间的线性关系分别为Y=0.662X+0.929(R~2=0.993),Y=0.776X+0.506(R~2=0.996),根据进食钙、磷与排泄钙、磷之间的相关关系可以外推出陕北白绒山羊断奶羔羊的内源损失钙、磷分别为0.929、0.506g·d~(-1)。沉积钙、磷与日增重之间的线性关系分别为Y=47.737 X-21.622(R~2=0.649),Y=53.770 X+18.973(R2=0.448)。结果显示,陕北白绒山羊断奶羔羊沉积钙、磷与日增重之间存在着线性关系。在本试验条件下,钙的最适添加水平为0.80%,磷的最适添加水平为0.45%。     

中草药添加剂"羊壮宝"饲喂羔羊增重效果的研究

在羊的日粮配合精料中添加中草药添加剂"羊壮宝",饲喂7月龄的萨福克羔羊,研究其对羔羊增重性能的影响。经过40 d的饲养试验,结果表明:添加"羊壮宝"的试验组与未加添加剂的对照组相比差异显著,试验组羔羊的日增重提高了92%,试验组每只羊比对照组羊只每天多收入1.57元。     

氨化麦秸对羔羊生产性能和生理生化指标影响的研究

选24只甘肃高山细毛羊当年羯羔,随机分成3组,分别饲喂基础日粮+氨化麦秸(Ⅰ组)、基础日粮+尿素+未处理麦秸(Ⅱ组)和基础日粮+未处理麦秸(Ⅲ组),饲喂50 d。测定羔羊的生产性能和16项生理生化指标。结果表明,Ⅰ组日增重和羊毛产量都显著高于Ⅱ组和Ⅲ组,日增重分别比Ⅱ、Ⅲ组提高44.95%(P<0.05)和181.46%(P<0.01),羊毛产量分别比Ⅱ、Ⅲ组提高31.16%(P<0.01)和115.27%(P<0.01)。羔羊体温、心率、呼吸及血液生化指标均无显著差异(P>0.05)。表明用氨化麦秸或直接添加尿素饲喂羔羊对其生理代谢无不良影响。     

Growth performance and meat characteristics of hair lambs grazing stargrass pasture without supplementation or supplemented with concentrate containing different levels of crude protein

Abstract

Forty crossbreed hair lambs (19.1 kg body weight; 8 months of age) grazing on a Cynodon plestoctachyus pasture without supplementation or supplemented with 300 g of concentrate containing different levels of crude protein (CP) were randomly assigned to treatments defined as follows: control (without supplementation); CP130 (concentrate 130 g CP/kg), CP150 (concentrate 150 g/kg), CP170 (concentrate 170 g/kg), and CP190 (concentrate 190 g CP/kg). Lambs fed supplements had higher final body weight (BW), total gain, average daily gain (ADG), total dry matter intake (DMI), total tract digestion, and carcass dressing than lambs in control treatment. Final BW, total gain, ADG, total DMI, feed conversion, and total tract digestion were improved linearly as protein level in concentrate increased. Meat of lambs fed supplements was lighter, redder, and less yellow than meat of lambs in control treatment. It is concluded that supplementation improved ADG, feed conversion, carcass dressing, and meat color.     

大豆皮替代羔羊饲粮中玉米或纤维成分对瘤胃消化率和生长性能的影响

通过瘤胃尼龙袋消化试验 (试验 1)和生长性能试验 (试验 2 )评价大豆皮替代羔羊饲粮中玉米或纤维饲料(玉米秸 )对瘤胃消化和生长性能的影响。饲粮处理为大豆皮替代饲粮中全部玉米 (SH C)、饲粮中 5 0 %纤维饲料(SH F)和对照饲粮 (CK)。试验 1结果表明 ,以大豆皮替代羔羊饲粮中全部玉米对于 2 4h和 4 8h干物质消化率(DMD)没有显著影响 (P >0 .0 5 ) ,但极显著降低了 2 4h和 4 8h细胞壁消化率 (NDFD) (P <0 .0 1) ;以大豆皮替代饲粮中 5 0 %纤维饲料显著提高了羔羊饲粮 2 4h和 4 8hDMD(P <0 .0 1)以及 4 8hNDFD(P <0 .0 5 )。试验 2结果表明 ,与对照组相比 ,SH C处理不影响羔羊日粮干物质采食量 (P >0 .0 5 )、日增重 (P >0 .0 5 )和饲料转化效率 (P >0 .0 5 ) ,但可以降低单位增重的饲料成本 ;SH F处理可以显著提高羔羊日粮干物质采食量 (P <0 .0 5 )、增重速度 (P <0 .0 1)和饲料转化效率 (P <0 .0 5 )。     

Effect of refined soy oil or whole soybeans on intake, methane output, and performance of young bulls

An experiment was conducted to establish the effects of feeding refined soy oil (RSO) or whole soybeans (WSB) containing soy oil on DMI, animal performance, and enteric methane (CH4) emissions in young bulls. Thirty-six Charolais and Limousin cross-bred, young beef bulls (338 +/- 27 kg of BW, 218 +/- 17 d of age at the beginning of the experiment) were blocked by BW, age, and breed before being assigned in a randomized complete block design to 1 of 3 experimental treatments (n = 12). The experimental period lasted for 103 d, with enteric CH4 output recorded for 2 periods of 5 consecutive days on d 37 to 41 and d 79 to 83. The 3 dietary treatments consisted of a barley/soybean meal-based concentrate with 0 g/d of RSO; oil from WSB as 6% of DMI (WSB treatment); and oil from RSO as 6% of DMI (RSO treatment). Each diet had a 10:90 forage:concentrate ratio, using barley straw as the forage source. Diet affected DMI (P < or = 0.001) and GE intake (P < 0.05 during the CH4 measurement periods), with the WSB treatment producing the lowest values. The addition of WSB decreased ADG (P < 0.05) compared with the RSO treatment. The WSB treatment also decreased (P < 0.05) average daily carcass gain (ADCG). Both the RSO and WSB concentrates decreased (P < 0.05 to P < 0.001) daily enteric CH4 output when expressed in terms of liters per day, liters per kilogram of DMI, percentage of GE intake, liters per kilogram of ADG, and liters per kilogram of ADCG. Diet had no effect (P = 0.557) on ruminal protozoal numbers. The reductions in enteric CH4 were achieved at relatively high oil inclusion levels. Such oil levels have previously been reported to decrease DMI of high-forage diets, although no effect on DMI was noted with the low-forage diets fed in this experiment. This impact on DMI of high-forage diets may limit the range of diets for which this CH4 reduction strategy may be applicable. The inclusion level of WSB in the current experiment (27%) was beyond the palatability threshold of the bulls used and resulted in a marked decline in intake and performance. Therefore, WSB may have a role to play in ruminant diets, but only at a reduced inclusion rate.     

Combinations of alfalfa hay and wet corn gluten feed in limit-fed growing diets for beef cattle

Two experiments were conducted to evaluate the effects of alfalfa hay (AH) and wet corn gluten feed (WCGF) combinations on ADG and gain efficiency of cattle limit-fed growing diets. In Exp. 1, crossbred beef steers (n = 220; initial BW = 262 kg) were limit-fed diets consisting of steam-flaked corn and 40% WCGF (DM basis) with 0, 10, or 20% ground AH (0AH, 10AH, and 20AH, respectively). A fourth diet containing 20% ground AH and steam-flaked corn served as a control. All diets were fed once daily at 1.8% of BW (DM basis). Growing period ADG, gain efficiency, and dietary NE calculated from performance data decreased linearly (P < 0.01) with addition of AH to diets containing WCGF. Rate of DMI increased linearly (P < 0.05) with AH addition to diets containing WCGF. Following the growing period, steers were finished on a common diet offered ad libitum. Gain efficiencies during the finishing period were higher (P < 0.05) for steers fed the 20AH diet than for steers fed the control diet. In Exp. 2, crossbred beef heifers (n = 339; initial BW = 277 kg) were limit-fed diets containing steam-flaked corn with 10, 20, or 30% ground AH and 0, 40, or 68% WCGF in a 3 x 3 factorial arrangement, fed once daily at 1.6% of BW (DM basis). An AH x WCGF interaction occurred (P < 0.05) for growing period ADG and gain efficiency. Increasing AH or WCGF decreased cattle ADG, gain efficiency, and dietary NE with the exception of heifers fed 30AH/40WCGF, which had ADG that did not differ (P > 0.10) from that of heifers fed 20AH/0WCGF or 30AH/0WCGF, and which had greater gain efficiencies (P < 0.05) than heifers fed 30AH/0WCGF. Rate of DMI increased linearly (P < 0.01) with increasing AH and decreased linearly (P < 0.01) with increasing WCGF. Heifers were finished on diets containing 33% WCGF with 0 or 0.5% added urea (DM basis) offered ad libitum. Increasing WCGF in growing diets tended (linear, P < 0.10) to increase finishing ADG and gain efficiency, whereas increasing AH decreased (linear, P < 0.05) kidney, pelvic, and heart fat, and the percentage of carcasses grading USDA Prime. Urea tended to increase ADG (P < 0.10), but decreased (P < 0.04) the percentage of carcasses grading USDA Choice. Results suggest that the value of WCGF relative to steam-flaked corn in limit-fed growing diets might be improved in diets containing 30% AH relative to diets containing 10 or 20% AH.     

Partial or total replacement of commercial concentrate with on-farm-grown mulberry forage: effects on lamb growth and feeding costs

Replacing commercial concentrate with mulberry foliage was evaluated in a feeding trial lasting 126 days. Forty-eight weaned male Pelibuey lambs (20.6?±?0.80 kg of BW) were randomly allocated to four groups: (1) supplementing the basal diet with mulberry at 1% (DM basis; M-1), (2) mulberry at 0.75% plus 0.1 kg concentrate fresh matter basis (M-0.75), (3) mulberry at 0.50% plus 0.2 kg concentrate (M-0.50) and (4) basal diet plus 0.3 kg concentrate (control; M-0). During the first 90 days, the basal diet was Pennisetum purpureum forage which was substituted by a mixture of guinea grass and sugarcane from 90 days. Average daily gain (ADG, g/day), dry matter intake (DMI) and feed conversion rate (FCR; DMI/ADG) were determined. The ADG was affected (P?<?0.01) by the diet, with the lowest obtained in M-1 lambs (71?±?6.4 g/day), whereas no differences among the other groups were observed (94?±?6.4 g DM/lamb). The DMI was higher (P?<?0.01) in M-0 (937 g DM/lamb) which concomitantly affected differences in FCR (11.9, 9.9, 10.5 and 9.7 kg DMI/kg BW gain for M-1, M-0.75, M-0.50 and M-0 lambs, respectively). Final BW at slaughtering and hot or cold carcass yields were coherent with growth rate findings. Biological yield (cold carcass weight/empty BW) was higher (P?<?0.01) in M-0.75. Without compromising animal productivity, replacing imported concentrate with mulberry reduced the feeding cost. Optimum results were obtained with M-75 diet. Further studies must be conducted for optimizing energy/protein ratios with different ingredients while increasing DMI and lamb growth rates in this tropical genotype.     

Effects of a dietary Aspergillus oryzae extract containing alpha-amylase activity on performance and carcass characteristics of finishing beef cattle

Three experiments were conducted to examine the effects of an Aspergillus oryzae extract containing alpha-amylase activity on performance and carcass characteristics of finishing beef cattle. In Exp. 1, 120 crossbred steers were used in a randomized complete block design to evaluate the effects of roughage source (alfalfa hay vs. cottonseed hulls) and supplemental alpha-amylase at 950 dextrinizing units (DU)/kg of DM. Significant roughage source x alpha-amylase interactions (P < 0.05) were observed for performance. In steers fed cottonseed hulls, supplemental alpha-amylase increased ADG through d 28 and 112 and tended (P < 0.15) to increase ADG in all other periods. The increases in ADG were related to increased DMI and efficiency of gain during the initial 28-d period but were primarily related to increased DMI as the feeding period progressed. Supplemental alpha-amylase increased (P = 0.02) the LM area across both roughage sources. In Exp. 2, 96 crossbred heifers were used in a randomized complete block design with a 2 x 3 factorial arrangement of treatments to evaluate the effects of corn processing (dry cracked vs. high moisture) and supplemental alpha-amylase concentration (0, 580, or 1,160 DU/kg of DM). Alpha-amylase supplementation increased DMI (P = 0.05) and ADG (P = 0.03) during the initial 28 d on feed and carcass-adjusted ADG (P = 0.04) across corn processing methods. Longissimus muscle area was greatest (quadratic effect, P = 0.04), and yield grade was least (quadratic effect, P = 0.02) in heifers fed 580 DU of alpha-amylase/kg of DM across corn processing methods. In Exp. 3, 56 crossbred steers were used in a randomized complete block design to evaluate the effects of supplemental alpha-amylase (930 DU/kg of DM) on performance when DMI was restricted to yield a programmed ADG. Alpha-amylase supplementation did not affect performance when DMI was restricted. We conclude that dietary alpha-amylase supplementation of finishing beef diets may result in increased ADG through increased DMI under certain dietary conditions and that further research is warranted to explain its mode of action and interactions with dietary ingredients.     

稻草加酶青贮饲喂育成牛的效果研究

本研究以新鲜晚稻草为原料，探讨了添加Ｓｔｒａｗｚｙｍｅ酶制剂对青贮晚稻草发酵品质和育成牛生产性能的影响。试验设３个处理，试验１组每吨稻草（ＤＭ）加酶８００克和麸皮５０千克；试验２组每吨稻草加酶８００克；对照组只加水调制。各处理和２组的采食量分别对照组高５８．６％，３２．２％；日增重分别比对照组高３４．３％和１１．８％。青贮晚稻草中添加Ｓｔｒａｗｚｙｍｅ可以改善青贮晚稻草的发酵品质，提高营养价值。     

Influence of S. babylonica extract on feed intake, growth performance and diet in vitro gas production profile in young lambs

An experiment was completed to determine the effect of Salix babylonica (SB) extract supplementation to the diet of growing lambs. Eighteen Katahdin × Pelibuey male lambs (14?±?2 kg live body weight) were divided randomly in individual cages into three groups and fed three diets varying in SB: a control group was fed on total mixed ration (TMR) without SB (SB0), an SB25 group was fed on TMR plus SB extract at 25 mL/lamb/day, and an SB50 group was fed on TMR plus SB extract at 50 mL/lamb/day on dry matter intake (DMI), average daily gain (ADG), feed efficiency, and in vitro gas production (GP) in lambs fed on TMR. In vitro GP of the TMR fed to lambs was recorded at 2, 4, 6, 8, 10, 12, 24, 48, and 72 h of incubation with 0, 0.6, 1.2, and 1.8 mL extract per gram of DM. Addition of SB extract at low and high doses improved the DMI of lambs by 59.9 and 33.2 %, respectively. Relative to the control, low and high extract doses achieved greater lamb ADG during the experimental period. The asymptotic GP increased (P?<?0.05) with increasing dose of SB extract without affecting the rate of GP or the initial delay before GP begins. Linear increases for in vitro GP with advancing time with different SB extract doses were observed. It is suggested that the use of S. babylonica extract with the rate of 25 mL/lamb/day is beneficial to young lamb’s performance growth and thus can be safely used as a feed additive in diets without any negative effects on animal health.     

Effects of supplemental zinc concentration and source on performance, carcass characteristics, and serum values in finishing beef steers

Three studies were conducted to examine the effects of zinc concentration or source in diets of finishing beef steers. In Exp. 1, 108 (British x Continental) beef steers were supplemented with concentrations of added zinc (as ZnSO4) at 20, 100, or 200 mg/kg of dietary DM. No differences (P > 0.10) were noted among treatments for ADG or gain:feed for the 112-d finishing period. However, a linear (P < 0.10) decrease was noted in daily DMI with increasing zinc concentrations for the overall finishing period. No differences (P > 0.10) were noted in hot carcass weight; dressing percentage; longissimus muscle area; percentage of kidney, pelvic, and heart fat; or marbling score. There were, however, quadratic increases in s.c. fat thickness (P < 0.05) and yield grade (P < 0.01) with added zinc. In Exp. 2, 12 beef steers were used to examine effects of added dietary zinc on serum concentrations of cholesterol and fatty acid profiles. No differences (P > 0.10) were observed in cholesterol or fatty acids among the supplemental zinc levels. In Exp. 3, 84 Brangus- and Angus-sired steers were fed a steam-flaked corn-based diet containing 30 mg of supplemental zinc per kilogram of dietary DM from one of the following sources: 1) ZnSO4, 2) Zn amino acid complex, or 3) a zinc polysaccharide complex. No differences (P > 0.10) were noted for the overall 126-d trial for ADG, DMI, or gain:feed ratio. Percentage kidney, pelvic, and heart fat was increased (P < 0.10) in steers supplemented with ZnSO4 vs the average of Zn amino acid and Zn polysaccharide complexes. However, s.c. fat thickness was greater (P < 0.10) in steers supplemented with Zn amino acid and Zn polysaccharide complexes vs ZnSO4. Serum zinc concentration did not differ (P > 0.10) among zinc sources. Supplemental zinc concentration in finishing diets did not seem to influence feedlot performance and had a minimal impact on carcass quality. Either the organic or inorganic source can be included in finishing diets without affecting feedlot performance.