肉牛宰后成熟阶段与食用品质相关指标的分析

通过测定宰后牛肉在不同时间内不同部位小片化指数、剪切力的变化数值,采用相关的方法得出:成熟时间对超微结构的改变起重要作用,肉牛宰后成熟时间应在5～6 d,肉牛胴体各部位间剪切力存在显著差异。     

全混合日粮营养水平对肉牛育肥效果的影响

采用完全随机单位组设计方法,设计并开展试验,评价TMR营养水平对肉牛增重效果、产肉性能和经济效益的影响,结果表明:提高TMR营养水平可以提高肉牛日增重8.79%、采食速度、降低采食量0.65%;可以改善屠宰性能,提高肉牛屠宰率0.47%、净肉率1.28%、胴体产肉率1.46%及优质切块肉的比重;可以提高饲料报酬;两种经济效益分别提高159.53元、385.79元。综合以上结果得出,提高TMR营养水平可以提高肉牛增重效果、产肉性能及经济效益。     

赤峰市优质肉牛饲养管理技术规程的应用

优质肉牛产业化在内蒙古赤峰市畜牧业发展中占有重要地位。肉牛业的发展对于调整优化畜牧业结构、增加农牧民收入、振兴国民经济等都有着非常重要的现实意义。《赤峰市优质肉牛饲养管理技术规程》是指导农牧民进行肉牛养殖的科学性、规范性、可操作性的技术规程,该规程有利于肉牛业可持续、健康、稳定发展,可以更好地推广应用肉牛饲养管理、繁殖改良、饲料调制、育肥等技术,可加快肉牛产业化、规模化、集约化、现代化发展的进程。     

Sustainable Management of Nutrients in Forage-Based Pasture Soils: Effect of Animal Congregation Sites (5 pp)

Background, Aim and Scope   Grazing animals have a dominant effect on the movement and utilization of nutrients through the soil and plant system, and thus on the fertility of pasture soils. Grazing can accelerate and alter the timing of nutrient transfers, and increase the amount of nutrients cycled from plant to soil. Long periods, position of shade, and water resources for grazing cattle can influence the spatial distribution of soil biochemical properties including soil organic carbon (C), total extractable inorganic nitrogen (TEIN), and Melich 1 extractable total phosphorus (TP). The objective of this study is to test whether cattle congregation sites typical on most Florida ranches, such as mineral feeders, water troughs, and shade areas are more nutrient-rich and may contribute more nutrients to surface and groundwater supply than in other pasture locations under Florida conditions. Materials and Methods: Baseline soil samples around and beneath three congregations sites in established (>10 yr) grazed beef cattle pastures at the United States Department of Agriculture (USDA), Agricultural Research Service (ARS), Subtropical Agricultural Research Station (STARS), Brooksville, FL, were collected in 2003, 2004, and 2005. Results: The levels of soil TEIN and TP were significantly (p ≤ 0.001) affected by the interaction of congregation sites and distance away from the center of the sites. Mineral feeders had the highest concentration of TP followed by shades and water troughs. The concentrations of soil TP decreased almost linearly with distance (x = meter) away from the center of the mineral feeders (-5.24x + 55.10; R2 = 0.92; p ≤ 0.001) and the shades (-6.25x + 57.21; R2 = 0.85; p ≤ 0.001). However, the level of TP around the water troughs (-0.25x + 16.91; R2 = 0.09) does not appear to change significantly with distance, staying close to about 13-18 mg kg-1. The levels of TEIN decreased linearly with distance away from the mineral feeders from the center of the shades. A linear model can describe the relationship between TEIN and distance away from the center of shades: -11.3x + 78.2; R2 = 0.95; p ≤ 0.001. The shaded sites (34.25 ± 1.7 mg kg-1) had higher levels than the mineral feeders (7.22 ± 0.60 mg kg-1) or water troughs (10.06 ± 0.8 mg kg-1) sites. Discussion: The higher soil TP near and around the mineral feeders can be attributed to the presence of phosphorus in the supplemental feeds. The average level of soil TP in the mineral feeders of 34.05 ± 0.44 mg kg-1 was not high enough to be of environmental concern. Losses of soil phosphorus by overland flow are becoming a big concern when the concentrations for soil phosphorus exceeded 150 mg kg-1 in the upper 20 cm of soils. With TN, the shaded sites (34.25 ± 1.7 mg kg-1) had either higher levels than the mineral feeders (7.22 ± 0.60 mg kg-1) or water trough (10.06 ± 0.80 mg kg-1) sites. Higher TEIN content at the shade sites may have been more likely due to frequent urination of animals and lack of vegetation immediately adjacent to shades. The lack of vegetation within and/or near the shades then had no uptake mechanism for removal of inorganic nitrogen, unlike the heavy demand for inorganic nitrogen by bahiagrass in other areas of the pasture. An accumulation of TEIN immediately adjacent to shades could lead to a potential point source that would be susceptible to leaching or gaseous losses to the environment. Conclusions: Early results of the study are suggesting that cattle congregation sites in beef cattle operations in Florida are not nutrient-rich, therefore may not contribute more nutrients to surface and groundwater supply under Florida conditions. Recommendations and Perspectives: Since there is no apparent vertical build up or horizontal movement of TEIN and TP in the landscape, we can then surmise that cattle congregation sites may be considered not a potential source of nutrients at the watershed level, at least on the sand ridge soils in Florida. Further research is continuing, including sampling at cattle congregation sites at other locations in north and south Florida, which started in July 2004.     

花生壳和麦秸用于饲养肉牛的营养价值和化学处理

为了评定花生壳、麦秸和花生壳-麦秸型典型肉牛日粮的营养价值，分析了粗饲料和日粮的营养成分，以3只瘤胃瘘管山羊和尼龙袋技术评价了粗饲料和日粮中干物质和粗蛋白质的瘤胃降解率，以5头肉牛进行了日粮消化率测定；对花生壳和麦秸分别进行氨化处理和综合化学处理，以不同组的肉牛进行60 d的饲养试验，比较氨化处理以及综合化学处理对粗饲料饲养效果的影响。结果表明，花生壳中粗纤维含量高于麦秸，花生壳和麦秸中粗蛋白质含量低、干物质降解率高而粗蛋白质降解率低；以花生壳和麦秸为主要成分的典型肉牛日粮，干物质和粗蛋白质的降解率高且稳定，其干物质、粗蛋白质和粗纤维的消化率分别为44.60%, 61.88% 和30.41%。以3.5%的尿素氨化处理花生壳及麦秸对肉牛具有良好的饲养育肥效果；对花生壳以3.5%的尿素和4%的Ca(OH)₂进行综合化学处理，其效果优于单纯的氨化处理。     

牛类胰岛素生长因子结合蛋白3基因PCR-SSCP分析

采用PCR-SSCP技术分析了牛类胰岛素生长因子结合蛋白3(IGFBP3)基因在南阳牛、鲁西牛和中国西门塔尔牛3个牛品种中的遗传多态性。结果表明:IGFBP3的第3外显子不存在遗传多态性;第2外显子在3个牛品种中检测到了AA、AB和BB基因型,而且A等位基因为3个牛群体的优势等位基因,分布较高。3个品种中,中国西门塔尔牛AA基因型频率最高,达到0.6615,而鲁西牛和南阳牛则相对较低,分别为0.4043和0.3095。对第2外显子的多态片段测序分析表明:位于IGFBP3基因第8069bp处发生单碱基突变T→C,并导致了苯丙氨酸变为亮氨酸。     

基于水温对肉牛生长性能影响的冬季恒温饮水系统优选

为缓解西北地区拴系肉牛在冬季产生的冷应激,提高肉牛生长性能,研究根据连通器原理设计恒温饮水系统,为牛只提供温水。试验选取西门塔尔牛作为试验牛,对饮水器内水温、肉牛的饮水行为、生理以及日增质量进行测定。试验结果表明:恒温饮水系统能为处理组牛只提供17.69℃的温水,处理组牛的日增质量为1.53 kg/(d·头),较对照组提高0.36 kg/(d·头),差异极显著(P0.01)。在处理组中,牛只饮用16~18℃的温水表现出更多的饮水次数和更好的增重效果(日增质量达到(1.69±0.44)kg/(d·头))。饮水后牛只瘤胃处体表温度处理组比对照组高3.29℃,差异极显著(P0.01)。结果表明,在拴系肉牛舍中采用这种恒温饮水系统能够有效改善肉牛因冬季饮用冷水造成的冷应激,并能显著提高肉牛生长性能,具有技术和经济可行性。     

用基于遗传算法的BP神经网络识别牛肉肌肉与脂肪

利用遗传算法的全局搜索能力,改进标准BP算法随机选取初始权重的不足,并构建了3-12-1的三层遗传BP神经网络,进行了3次牛肉肌肉与脂肪像素的分类试验,研究用BP网络对牛肉肌肉与脂肪两类像素点进行识别的可行性。以像素点的RGB值作为BP网络输入向量,每次训练集样本数62,测试集样本数43。测试的最终结果为：训练集的样本识别率分别为100%、100%、98.3871%;对应测试集的样本识别率分别为97.6744%、97.6744%、100%。试验结果表明,尽管基于遗传算法的BP神经网络对训练样本集以及测试样本集的肌肉和脂肪的识别率均在97%以上,但由于牛肉图像像素值在颜色空间中比较分散,有利于聚类的规律性不明显,因而是否可用BP网络来完成肌肉与脂肪的识别,还需要在网络拓扑结构、训练样本集等方面进一步研究。     

泌阳县肉牛养殖常用饲料原料中微量元素及重金属含量分析

[目的]饲料原料中微量元素和重金属的含量对肉牛的生长发育及生态环境均有重要影响,通过对肉牛养殖中常用饲料原料中的微量元素及重金属含量进行分析,为肉牛养殖提供参考.[方法]研究对泌阳县境内24份肉牛养殖常用的饲料原料样品进行分析,采用硼氢化钾还原原子荧光光谱法测定了饲料原料中4种微量元素(铜、铁、锌、硒)及2种重金属(砷...     

Change of plasma insulin-like growth factor-1 (IGF-1) concentration with early growth in Japanese beef cattle

The aim of the present study was to examine the change in plasma insulin‐like growth factor‐1 (IGF‐1) concentration with early growth, changes of bodyweight (BW) and relative dairy gain (RDG) in the pre‐ (PRW) and postweaning periods (POW) in Japanese beef cattle, and relationships with metabolites. A total of 33 calves, 22 Japanese black, 6 Japanese shorthorn and 5 of their crossbreed were studied. Insulin‐like growth factor‐1 and metabolite (glucose, triacylglycerol, nonesterified fatty acid) levels in the plasma, from jugular vein blood taken every month, were measured along with BW. Insulin‐like growth factor‐1 in POW increased dramatically with increase of BW (P < 0.05), and the correlation was positive at 0.52 (P < 0.01). Glucose levels correlated significantly with BW, RDG and IGF‐1 (P < 0.01). Metabolic required calorie correlated positively with IGF‐1 (P < 0.01). Also, correlations of BW in POW, with BW and RDG in PRW were positive (P < 0.01). Growth in PRW would be influenced by maternal effects, while active self‐secretion of IGF‐1 in POW might contribute to POW growth. These factors suggested that to increase growth in PRW, maintaining enough maternal effect and IGF‐1 level in POW, was important for establishing better growth after weaning.