Effects of Maize Silage Harvest Stage on Growth Performance and Economic Benefits of Beef Cattle

[Objectives]This study aimed to investigate the effects of whole-crop maize silage harvested at different stages on growth and economic benefits of beef cattle.[Methods]A total of 30 Simmental crossbred cattle weighing about 378 kg were randomly divided into three groups,respectively fed for 70 days with whole-crop maize silage harvested at milk stage(GroupⅠ),dough stage(GroupⅡ)and physiological maturity stage(GroupⅢ).Moreover,the cattle in all groups were given the same concentrate diet.[Results]There were significant differences in dry matter,crude protein and neutral detergent fiber between whole-crop maize silages harvested at different stages(P<0.05).The dry matter in GroupⅡandⅢwas significantly higher than that in GroupⅠ(P<0.05).The crude protein content peaked in GroupⅡ,up to 6.37%,which was significantly higher than that in GroupⅠ(by 12.74%,P<0.05)and GroupⅢ(by 9.26%,P<0.05).Starch content significantly increased with the postponing of maize harvest(P<0.05).The content of neutral detergent fiber in Group I was significantly higher than that in GroupⅡ(P<0.05)and GroupⅢ(P<0.05).The average daily weight gain in GroupⅡwas 8.53%higher than that in GroupⅠ(P<0.05)and 3.70%higher than that in GroupⅢ(P>0.05).The dry matter intake in GroupⅡwas significantly higher than that in GroupⅠ(P<0.05)and GroupⅢ(P<0.05).There was no significant difference in feed/gain ratio between the groups(P>0.05).The economic benefit in GroupⅡwas the highest,up to 9.99 yuan/day per capita.,followed by that in GroupⅢ,9.79 yuan/day per capita,and that in GroupⅠwas the lowest,only 8.03 yuan/day per capita.[Conclusions]The whole-crop maize silage harvested at dough stage has the best quality and produces the highest economic returns for beef cattle.

EFFECTS OF HARVEST STAGE ON THE TOTAL LIPID AND FATTY ACID COMPOSITION OF FOUR CYLINDROTHECA STRAINS

Four strains of Cylindrotheca (B156, B164, B196, and B200) were harvested at three phases in the growth curve and their total lipid and fatty acid composition were determined. Total lipid reached highest values in the late stationary phase in B156 (24.0%), B164 (26.6%) and B200 (17.3%), in the exponential phase in B196 (15.5%). Saturated fatty acids increased with the development of the culture in B156 and B196, and reached their highest values in the late stationary phase in B156 (41.7%) and B196 (45.1%), in the early stationary phase in B164 (45.4%) and B200 (37.6%). Monounsaturated fatty acids increased with the development of the culture in B196 and B200, and reached their highest values in the late stationary phase in B196 (32.4%) and B200 (32.8%), in the early stationary phase in B164 (31.0%) and in the exponential phase in B156 (29.3%). Polyunsaturated fatty acids decreased in the later phases of the culture in B164, B196 and B200, and peaked in the exponential phase in B164 (29.5%), B196 (42.9%) and B200 (37.3%), and in the early stationary phase in B156 (32.0%).

Growth Dynamics and Optimal Harvesting Stage of Two Forage Maize Varieties

SAUMZ 1 and SAUMZ 2 are two forage maize varieties reproduced by distant hybridization.In a randomized block experiment,their fresh forage yield and dry matter yield were investigated on the basis of growth period,leaf stage,and effective accumulated temperature.The nutritional components were measured in a near infrared diffuse reflectance spectroscopy.Referring to the concept of forage grading index,a formula was constructed to calculate the total digestible energy.The investigated characters and indexes were adapted to suitable models of growth dynamics.The results showed that these two varieties have strong heterosis in fresh forage yield,dry matter yield,and total digestible energy.Their growth dynamics were adapted to Logistic models described by general equation y=k/（1＋ae-bx）.The forage grading indexes of these two varieties were decreased linearly along with the increasing of their leaf stage.The stopping point of fast growing period of total digestible energy estimated on the basis of leaf stage was suggested to be used as optimal harvesting stage of forage maize.The optimal harvesting stage was estimated to be tasseling stage for SAUMZ 1 and 19.50-leaf stage for SAUMZ 2.

OPTIMAL HARVESTING AND STABILITY FOR FISHING MODELS WITH STAGE STRUCTURE IN INSHORE-OFFSHORE AREAS

A fishing model with stage structure in inshore and offshore areas is considered.Steady states of the dynamical system representing fishery are derived and their local,as well as global,stability is discussed.The optimal harvest policy is formulated and solved as an optimal control problem.A numerical example is given to illustrate the solution procedure.

Permanence and global attractivity of stage-structured predator-prey model with continuous harvesting on predator and impulsive stocking on prey

We investigate a stage-structured delayed predator-prey model with impulsive stocking on prey and continuous harvesting on predator. According to the fact of biological resource management, we improve the assumption of a predator-prey model with stage structure for predator population that each individual predator has the same ability to capture prey. It is assumed that the immature and mature individuals of the predator population are divided by a fixed age, and immature predator population does not have the ability to attach prey. Sufficient conditions are obtained, which guarantee the global attractivity of predator-extinction periodic solution and the permanence of the system. Our results show that the behavior of impulsive stocking on prey plays an important role for the permanence of the system, and provide tactical basis for the biological resource management. Numerical analysis is presented to illuminate the dynamics of the system.

不同成熟期对花椰菜种子活力及相关生理生化指标的影响

花椰菜种子收获时常依据经验进行,易导致采收时期不当,对种子质量造成较大的影响。为研究花椰菜杂交种子成熟期与种子活力的关系,确定适宜的种子收获期,本研究以花椰菜品种瓯松60天为材料,分析了授粉后40、45、50、55、60、65 d不同成熟期种子物理性状、种子活力和抗氧化酶活性等指标变化。结果表明,随着种子成熟期延长,种子含水量、鲜种子千粒重呈降低趋势,种子浸泡液电导率和丙二醛(MDA)含量先降低后趋于稳定,规定水分千粒重、超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性、发芽率、发芽势、活力指数、苗高、根长先增加后趋于稳定。不同授粉后天数之间比较结果表明,授粉后55、60、65 d,活力指数、苗高和根长差异不显著,但均显著高于50 d;规定水分千粒重、SOD活性、POD活性、MDA含量、电导率在授粉后55 d趋于稳定。回归分析结果表明,活力指数与鲜种子千粒重、种子含水量、MDA含量、电导率显著(P<0.05)或极显著(P<0.01)线性负相关,与SOD和POD活性极显著线性正相关(P<0.01)。活力指数、SOD活性、POD活性、MDA含量、电导率与种子发育天数符合二项式函数变化:y_(活力指数)=-0.131x2+16.957x-344.480,y_(SOD活性)=-0.020x2+2.668x-10.420,y_(POD活性)=-0.112x2+14.417x-368.610,y_(MDA含量)=0.113x2-13.771x+433.780,y_(电导率)=0.088x2-10.319x+338.680,达显著或极显著水平,可用来预测不同发育天数种子的活力、保护酶清除活性氧自由基能力和细胞膜结构的完整性。综上,授粉后55 d,瓯松60天种子已达可采收程度,发芽率98%,规定水分千粒重4.364 g,种子活力和种子生理也趋于稳定,且对幼苗生长没有影响,还可降低种子易落粒损失风险。本研究结果为花椰菜杂交种子适时采收提供了理论依据。

不同采收期枇杷叶中氨基酸的组成与分析

目的 对12个月份采收期枇杷叶的氨基酸成分组成及含量变化进行分析,为确定枇杷叶采收期及资源利用提供理论依据。方法 采用异硫氰酸苯酯柱前衍生化高效液相色谱法测定不同月份枇杷叶氨基酸组成及含量;采用SPSS22.0版软件进行数据统计学差异及相关性分析;根据世界卫生组织(WHO)和联合国粮农组织(FAO)提出的理想模式及朱圣陶提出的氨基酸比值系数法,对不同采收期的枇杷叶氨基酸进行评分。结果 不同采收期枇杷叶中均含有17种氨基酸,7种人体必需氨基酸(EAA)、9种儿童必需氨基酸(CEAA)及9种药用氨基酸。17种氨基酸分别是天门冬氨酸、谷氨酸、丝氨酸、甘氨酸、组氨酸、精氨酸、苏氨酸、丙氨酸、脯氨酸、酪氨酸、缬氨酸、甲硫氨酸、胱氨酸、异亮氨酸、亮氨酸、苯丙氨酸、赖氨酸,它们的平均含量分别为3.41~7.23、4.64~9.66、2.05~3.75、2.99~4.95、0.01~1.56、2.33~4.85、2.10~4.03、2.67~5.48、5.37~7.64、1.45~3.49、2.70~5.53、0.01~0.48、3.64~4.78、1.91~4.15、3.96~7.83、2.39~4.60、1.85~3.65 mg·g^(-1)。不同采收期枇杷叶中17种氨基酸、总氨基酸(TFAA)、EAA总量、CEAA总量、药用氨基酸、苦味氨基酸的含量间差异有统计学意义(P<0.05);苦味氨基酸在总氨基酸中的百分含量较稳定。不同采收期枇杷叶的EAA含量为44.26%~50.33%,明显高于WHO/FAO模式值(35.00%);EAA/非必需氨基酸(NEAA)均值(55.67%)和EAA/TFAA均值(35.74%)分别接近WHO/FAO模式值的60%、40%;不同采收期枇杷叶的17种氨基酸含量峰值前2位是7月和11月;氨基酸比值系数分(SRC)值为62.53~76.17,前3位为11月、8月及7月。赖氨酸为枇杷叶的第一限制氨基酸。苦味氨基酸与药用氨基酸、TFAA呈正相关(P<0.01)。结论 枇杷叶中氨基酸种类齐全,组成合理,具有较佳开发利用价值;不同月份氨基酸的含量差异大,7月和11月是枇杷叶氨基酸合理开发利用的较佳时期。

鲜食玉米收获机械发展阶段判定研究——基于收获效率与果穗损失视角

为促进鲜食玉米的高效低损收获,对鲜食玉米收获机械的发展进行阶段划分,并结合收获效率与果穗损失2个方面构建特征模式,基于模糊数学理论提出一种阶段划分方法,并结合4YZ-6型鲜食玉米收获机田间试验对该方法进行检验与可行性分析。结果表明该收获机收获效率与果穗损失率均低于2470型收获机,与判定的低效低损阶段相符。该阶段划即判定方法的提出,有助于加快我国鲜食玉米收获机械的高效低损发展,补全国内鲜食玉米机械化收获的短板问题。

不同采收期和冷藏期对四川“清见”杂柑品质特性的影响

采收期影响果实在贮藏期间的果实质量。为进一步延长四川“清见”杂柑的货架期,研究了4个采收期(1月29、2月26、3月26和4月25)和(4±0.5)℃下5个冷藏期(30、60、90、120和150 d)对其品质的影响。结果显示,柑橘颜色指数、总可溶性固形物(Total Soluble Solid,TSS)、固酸比、蔗糖、葡萄糖、果糖、奎尼酸和苹果酸含量随采收期的延长显著增加(P<0.05),分别从采收Ⅰ期到Ⅳ期增加了21.81%、17.99%、33.33%、41.56%、51.22%、54.38%、82.59%、34.74%;而b*值、硬度、可滴定酸(TitratableAcid,TA)、柠檬酸和丁二酸含量随采收期的延长显著下降(P<0.05),分别下降了15.57%、39.85%、32.61%、30.95%和33.04%。同时,采收期的延长可使冷藏期果实的TSS、固酸比和蔗糖含量提前30 d达到峰值,TA含量提前30 d降到最低值。果实综合品质主成分分析(Principal Component Analysis,PCA)结果表明,现采果在采收Ⅳ期、冷藏果在采收Ⅰ期放置60 d和150 d时综合品质最佳。综上,采收期和冷藏期对四川“清见”杂柑品质影响显著且存在交互作用,采收Ⅳ期最适鲜销,采收Ⅰ期在单纯实验理想状态下(未进行经济方面考量)最适长期低温贮藏后销售。

云南瑞丽4个主栽柑橘品种成熟期果实品质变化规律

【目的】探究云南瑞丽地区主栽柑橘品种成熟期果实品质变化规律,为确定果实适时采收期提供理论依据。【方法】以云南主栽的4个柑橘品种(沃柑、冰糖橙、茂谷柑、W·默科特)为试材,分别从花后150~330 d(2020年8月12日—2021年2月8日)和花后240~405 d(2021年11月8日—2022年4月28日)开始采果,每隔15 d定期采样并测定果实品质。【结果】随着柑橘果实的成熟,4个品种果实单果质量及横、纵径呈先上升后平缓的趋势,沃柑在花后270 d前、冰糖橙在花后255 d前、茂谷柑在花后300 d前、W·默科特在花后285 d前其果实结束快速生长膨大期;2年内,除茂谷柑转色期一致外,W·默科特果皮转色期早于第1年,沃柑和冰糖橙转色期晚于第1年。冰糖橙、沃柑、茂谷柑和W·默科特的可溶性固形物(TSS)质量分数分别在其花后240、315、300、270 d后基本稳定,可滴定酸(TA)质量分数分别在花后180、210、240、240 d后无显著变化。【结论】综合考虑单果质量、横纵径、果皮颜色和内含物质量分数等指标,沃柑在花后315 d、冰糖橙在花后255 d、茂谷柑在花后300 d、W·默科特在花后285 d时果实达到采收成熟度,适宜开始采收。

不同生长年限子洲黄芪休眠期的质量差异

目的:比较不同生长年限子洲黄芪休眠前期和休眠后期的有效成分含量,揭示子洲黄芪在休眠期各有效成分的变化规律,确定子洲黄芪的最适采收期。方法:采用随机取样法收集8批不同生长年限休眠前期及休眠后期的子洲黄芪,以黄芪甲苷、毛蕊异黄酮葡萄糖苷和水溶性浸出物质量分数为指标,结合聚类分析法分析其质量差异。结果:各指标含量测定结果显示,随生长年限的增加,各成分含量呈规律性动态变化。黄芪甲苷与毛蕊异黄酮葡萄糖苷质量分数均在生长5年时达到最高值,分别为0.166%、0.079%;水溶性浸出物质量分数在生长7年时达到最高值,为21.290%。对不同生长年限休眠前期和休眠后期的各成分含量进行对比发现,休眠后期黄芪甲苷质量分数显著下降,且下降幅度逐年增大,生长7年时下降幅度最大,为54.09%;毛蕊异黄酮葡萄糖苷质量分数增加,生长5年时增幅最大,为145.83%;水溶性浸出物质量分数生长7年时增幅最大,为18.40%。结论:子洲黄芪有效成分积累受生长年限及采收时间的影响,且变化趋势不一致,如以毛蕊异黄酮葡萄糖苷为指标,宜在生长5年休眠后期采收;如以黄芪甲苷为指标,宜在生长5年休眠前期采收;若综合考虑黄芪甲苷及毛蕊异黄酮葡萄糖苷含量,宜在生长6年休眠前期采收。

基于湿法收获苜蓿草捆阶段式热风干燥试验与工艺优化

通过苜蓿干燥加工工艺的分析,依据湿法收获加工工艺研究内强制式苜蓿草捆的热风干燥特性。为提高内强制式苜蓿草捆的干燥效率,优化干燥工艺流程,依据苜蓿草捆干燥特性试验数据,确定苜蓿草捆的内强制阶段式干燥工艺和工艺控制参数。试验在干燥热风量为2 500 m3/h、3 000 m^(3)/h、3 600 m^(3)/h保持不变时,测试不同干燥温度对苜蓿草捆含水率和干燥速率的影响。试验结果表明,草捆干燥工艺优化前,在干燥风量为3 600 m3/h,干燥温度为120℃时,草捆的干燥时间是37.5 min,耗电量为160 kWh/t,草捆干燥品质达到一级标准;工艺优化后,采用阶段式干燥工艺,在干燥风量为3 600 m^(3)/h,干燥温度设为120℃时,草捆的干燥效率提高近20%,能耗节省12.5%,草捆品质无显著差异。因此,采用优化后的干燥工艺,有效地保持苜蓿的营养品质,显著提高苜蓿草捆的干燥效率和内强制式热风干燥的热效率,为苜蓿干燥的规模化生产提供技术支持。

高粱机械化收获效果影响因素分析研究

针对高粱收获过程中的籽粒损失、破碎和含杂等问题,研究成熟时期和机收速率等因素对联合收获作业效果的影响规律。以晋杂22号高粱为研究对象,采用小区作业试验方案,分别在乳熟期、蜡熟期和完熟期设置3个机收速率水平进行高粱联合收获作业,机收速率设置为0.5 m/s,1.0 m/s,1.5 m/s,并测定破碎率、含杂率、总损失率与含水率等指标,获得成熟时期与机收速率对收获效果的影响规律。结果表明:成熟时期和机收速率对高粱籽粒含杂率、破碎率、总损失率等收获指标影响均极显著,对3项收获指标影响最大的因素均为成熟时期;在蜡熟期和机收速率为1.0 m/s时进行高粱联合收获作业能取得最佳效果,此时籽粒含水率为14.756%~15.746%,含杂率为0.14%,破碎率为0.29%,总损失率为5.48%。该研究获得了成熟时期和机收速率对高粱收获效果的影响规律,可为高粱机械化收获成熟时期合理选择与收获技术推广提供理论依据。

玉米收获机械化技术推广应用探讨

随着农业现代化发展步伐的加快,玉米作为北方地区常见的粮食作物之一,其种植和收获的机械化水平也得到了显著提高。玉米机械化收获技术可以显著提高作业效率,降低劳动强度,并且可以使玉米的生产成本不断降低,有利于玉米种植效益的增加。结合玉米生长特点,对其收获阶段机械化技术的应用进行分析,并指出了当前常见的玉米收获机械及其特征,提出了推广应用玉米机械化收获技术的建议,为此项技术的推广应用提供参考。

余甘子果实不同发育阶段品质比较

为了解余甘子果实品质随果实发育的动态变化规律,以‘高黎贡山’和‘保山2号’两个余甘子品种为研究材料,于4个不同发育阶段(7月16日、9月1日、10月15日、11月30日)分别采集两个品种的果实测定其水分、可溶性固形物、可食率、总酸、总糖、维生素C、单宁酸、多酚和没食子酸含量等指标,分析其动态变化规律;基于各品质指标间的相关性进行分析,并利用主成分分析对各发育阶段果实品质指标进行综合评价,以确定适宜采收期。结果表明,同品种余甘子所测定的品质指标在不同发育阶段差异极显著(P<0.01)。各个指标在果实发育趋向成熟的过程中的变化趋势因指标而异,总酸、总糖、维生素C和多酚含量随着果实不断发育呈先升高后降低的趋势,可溶性固形物含量则先降低后升高。‘高黎贡山’和‘保山2号’余甘子的总糖和多酚相关系数最高,均在0.9以上。基于所有品质指标测定及分析结果,认为10月15日左右为两个品种余甘子果实的最佳采收期,此时采摘的‘高黎贡山’和‘保山2号’余甘子总酸、维生素C、总糖、单宁酸、多酚含量均最高,‘高黎贡山’的可溶性固形物和‘保山2号’的没食子酸含量亦最高。

Optimum harvesting time of herbaceous peony buds for cutting flowers

The herbaceous peony is one of the cut flowers that has become increasingly popular in the international market in recent years. In the study, 11 cultivars of herbaceous peonies suitable for cutting flowers were selected; different harvesting stages （three or four stages） were identified according to bud development observation （bud firmness, bud diameter, sepal angle, petal angle, and color showing）. Moreover, flower development and vase life were also recorded in the experiment of vase. Bud development observation shows that there are great differences in optimum harvesting stage between the culti- vars, especially between the hybrid peony group and lactiflora group. This implies that bud diameter could not be the only indicator for optimum harvesting stage. Bud description, including sepal opening angle, sepal color, petal color showing, and degree of firmness, is necessary for the determination of the harvesting stage. Among the 11 cultivars,‘Pink Hawaiian Coral＇, ‘Red Charm＇, ‘Edulis Superba＇, ‘Red Magic＇, and ‘Sarah Bernhardt＇ should be harvested at stage 1. ‘Duchesse de Nemours＇, ‘Taff＇, ‘Sorbet＇ and ‘Monsieur Jules Elie＇ should be harvested at stage 2. ‘Kansas＇ should be at stage 3 and ‘Karl Rosenfield＇ at stage 4. The determination of optimum harvesting stage for each cultivar is an important element in cut flower production.

Dry Matter Partitioning and Harvest Index Differ in Rice Genotypes with Variable Rates of Phosphorus and Zinc Nutrition

Phosphorus （P） and zinc （Zn） deficiencies are the major problems that decrease crop productivity under rice-wheat cropping system. Field experiments were conducted to investigate impacts of P （0, 40, 80 and 120 kg/hm^2） and Zn levels （0, 5, 10 and 15 kg/hm^2） on dry matter （DM） accumulation and partitioning, and harvest index of three rice genotypes ＇fine （Bamati-385） vs. coarse （F-Malakand and Pukhraj）＇ at various growth stages （tiliering, heading and physiological maturity）. The experiments were conducted at farmers＇ field at Batkhela in Northwestern Pakistan for two years in summer 2011 and 2012. The two year pooled data reveled that there were no differences in percent of DM partitioning into leaves and culms with application of different P and Zn levels, and genotypes at tillering. The highest P level （120 kg/hm^2） partitioned more DM into panicles than leaves and culms at heading and physiological maturity stages. The highest Zn level （15 kg/hm^2） accumulated more DM and partitioned more DM into panicles than leaves and culms at heading and physiological maturity stages. The hybrid rice （Pukhraj） produced and partitioned more DM into panicles than F-Malakand and Bamati-385 at heading and physiological maturity stages. Higher DM accumulation and greater amounts of partitioning into panicles at heading and physiological maturity stages was noticed with increase in P and Zn levels, and the increase was significantly higher in the coarse rice genotypes than fine. We concluded that the growing hybrid rice with application of 120 kg/hm^2 P ＋ 15 kg/hm^2 Zn not only increases total DM accumulation and partitioned greater amounts into the reproductive plant parts （panicles） but also results in higher harvest index.

Effects of harvesting method and date on yield loss and seed quality of rapeseed

China is one of the major rapeseed production countries in the world,but harvesting mechanization was still backward,and high harvest loss was a key inhibiting factor for rapeseed production.To obtain optimum harvesting date for winter rape in the Yangtze River Valley of China,artificial simulated combine harvesting and artificial two-stage harvesting were adopted to find correlations between harvesting date,rape variety,seed oil content,protein content,grain moisture rate,rapeseed straw moisture content,rapeseed unthreshing rate,grain drop loss rate,thousand seeds weight(TSW),and harvesting economic coefficient(HEC).Analysis of variance showed that rapeseed oil content,protein content and TSW were correlated with rape variety;HEC was correlated with harvesting method and rape variety.Rape variety was the dominant factor of rapeseed oil content,protein content,TSW and HEC.Grain moisture rate,un-threshing rate,grain drop loss rate and straw moisture content were correlated with harvesting method and date.Harvesting date was the dominant factor of rapeseed moisture rate,un-threshing rate,grain drop loss rate and straw moisture rate.Single factor tests further proved that harvesting date had less impact on rapeseed oil content,protein content,TSW and HEC.It showed little correlation with rapeseed quality except grain moisture rate.The optimum harvesting date could be known by change in straw moisture content.The combined harvesting should be carried out during the grain moisture content of 15%-20%with TSW stabilized in the highest level.The twostage harvesting cutting should be carried out at the grain moisture content of 35%-40%.This research offered a reference to harvesting method and date for rape cultivated in the Yangtze River Valley.

Harvest Time and Fertility Effects on Yield and Quality of Forage from Alfalfa, Hybrid Bromegrass and Their Mixture

A field experiment with 24 treatments consisting of three perennial forage crops [alfalfa (Medicago sativa L. cv. AC Longview), hybrid bromegrass (Bromus riparius Rehm & Bromus inermis Leyss. cv. AC Success) and their mixture], four Cut 1 dates (approximately June 20, July 10, July 30 or August 20), and two fertilizer levels (unfertilized and fertilized) was established in late May 2014, on a Black Chernozem [Udic Boroll] silty clay soil. Forage dry matter yield [DMY], and concentration (g·kg−1 DM) of crude protein [CP], total digestible nutrients [TDN] and acid detergent fiber [ADF] data were collected over 3 years from 2015 to 2017. The fertilizer treatments were imposed in 2016 and 2017. Forage crops were initially cut at four Cut 1 dates, and again cut [Cut 2] in autumn (September 2 in 2015, November 7 in 2016 and October 5 in 2017). For all three forage crops, forage DMY usually increased when Cut 1 was delayed. Delaying Cut 1 reduced forage DMY for Cut 2. Total DMY (Cut 1 + Cut 2) for all three forage crops was highest from the combination of July 10 and late Autumn cuts. Alfalfa-bromegrass mixture produced higher DMY than bromegrass or alfalfa alone. Fertilizer application resulted in a significant increase in Cut 1 and total DMY for bromegrass. The CP concentration in Cut 1 forage usually declined as the forage crops matured. The CP concentration was highest for alfalfa, followed by alfalfa-bromegrass mixture, and much lower for bromegrass. There was little or no effect of forage crop maturity on the TDN and ADF concentrations in forage. The TDN concentration was higher and ADF concentration was lower in forage from alfalfa or alfalfa-bromegrass mixture than bromegrass. Fertilizer application significantly increased CP concentration for alfalfa-bromegrass mixture. Delaying harvesting for Cut 1 increased ADF yield and TDN yield until Late July, but CP yield generally decreased with crop maturity. The ADF yield and TDN yield were higher for alfalfa-bromegrass mixture than bromegrass or alfalfa alone, and CP yield was similar for alfalfa and alfalfa-bromegrass mixture but considerably higher than bromegrass. Fertilizer application increased CP yield and ADF yield for bromegrass and alfalfa-bromegrass mixture, and TDN yield only for bromegrass. In conclusion, total DMY (Cut 1 + Cut 2) was highest for a combination of Early July and Autumn cuts. Forage yield was highest for alfalfa-bromegrass mixture, followed by alfalfa and lowest for bromegrass. The CP and TDN concentrations were higher, and ADF concentrations were lower in forage from alfalfa or alfalfa-bromegrass mixture than bromegrass.

品种和生育期对玉米青贮发酵品质的影响

为阐明品种和生育期对青贮玉米(Zea mays)发酵品质的影响,本研究以3个青贮玉米品种‘曲辰9号’‘宣宏18号’‘桥单6号’为材料,在抽穗期、乳熟期、蜡熟期收获加工调制成青贮饲料,并分析青贮发酵品质。结果表明:1)随着生育期的延长,青贮饲料感官评分均呈增加趋势。各品种青贮后,干物质含量、淀粉含量均随着生育期延长而增加,中性洗涤纤维、酸性洗涤纤维含量和pH均以抽穗期较高,乳熟期和蜡熟期较低。2)不同时期收获,‘曲辰9号’3个生育期青贮饲料平均青贮发酵品质评分为0.50分,‘宣宏18号’为0.43分,‘桥单6号’为0.51分,‘曲辰9号’和‘桥单6号’青贮饲料营养价值较高,表现较好。3)隶属函数分析表明,玉米青贮最佳生育期为蜡熟期。在蜡熟期收获,‘曲辰9号’综合评分为0.67,高于‘宣宏18号’(0.62)和‘桥单6号’(0.61)。故本研究推荐‘曲辰9号’在蜡熟期收获作为调制青贮饲料的原料使用。