储藏环境对菜籽油酸值和过氧化值的影响研究

通过模拟储藏,研究了水分、温度和光照对菜籽油酸值和过氧化值的影响。结果表明,同一温度时,随着储藏时间的延长,水分含量基本不变,但酸值和过氧化值逐渐升高,水分含量越高,升高越明显;同一水分时,随着储藏时间的增加,其酸值和过氧化值不断增加,温度越高,增加越明显。方差分析表明,菜籽油的酸值和过氧化值与水分、温度和储藏时间具有显著的线性关系。光照与避光保藏相比,菜籽油的酸值和过氧化值增加明显。菜籽油适宜低温、干燥和避光储藏。     

小桐子毛油储藏中品质变化研究

将水分为0.1%、0.5%、1.0%的小桐子毛油,以棕色塑料瓶、白色塑料瓶和透明玻璃瓶密封包装后在20、30、40℃的条件下储藏160 d,每20 d测定1次酸值和过氧化值,研究小桐子毛油在不同储藏条件下品质变化情况。结果表明:随着储藏温度的升高、小桐子毛油水分的增加以及储藏时间的延长,小桐子毛油的酸值和过氧化值均增加。采用正交实验得到小桐子毛油适宜的储藏条件为:棕色塑料瓶密封包装,水分0.1%,储藏温度15℃;在此条件下,小桐子毛油储藏180 d后,其过氧化值上升,酸值未发生明显变化。     

不同储藏条件下糙米脂肪酸值变化研究

对不同水分、温度、氧气浓度条件下储藏的糙米定期进行脂肪酸值测定,糙米的水分分别为13.5%、14.5%、15.5%、16.5%,放入温度分别设定为30、25、20、15℃的恒温箱中储藏,氧气的体积分数为2%、5%、8%、21%,储藏时间为180天,每30天检测1次.结果表明,随着储藏时间的延长,糙米样品中脂肪酸值呈先增加继而又下降的趋势;经方差分析得出,储藏时间、温度、水分、氧气浓度对糙米脂肪酸值影响极显著(P<0.01),温度、水分越高,糙米的脂肪酸值上升越快;低浓度氧气可延缓脂肪酸值变化.经过多重差异比较得出,用4种不同温度储藏糙米,其脂肪酸值差异极显著(P<0.01);在温度为20～30℃及不同水分条件下储藏糙米,其脂肪酸值差异均极显著(P<0.01);在15～C条件下,15.5%与14.5%差异显著(P<0.05),其他水分梯度差异极显著(P<0.01);水分16.5%的糙米储藏在25℃,氧气体积分数分别为8%、21%条件下,其脂肪酸值差异不显著,其他浓度氧气差异极显著(P<0.01);水分14.5%的糙米储藏在15℃,不同体积分数的氧气条件下,其脂肪酸值差异均极显著(P<0.01).实验证明,低温、低水分储藏糙米可以抑制脂肪酸值的上升,低浓度氧气可以延缓脂肪酸值的下降.     

葵花籽油的氧化稳定性研究

以葵花籽油的酸值和过氧化值为评价指标,考察了温度、光照、金属离子、氧气、水分对葵花籽油氧化稳定性的影响。结果表明：温度、光照、金属离子、氧气、水分均会引起储藏过程中葵花籽油的酸值和过氧化值的升高,且温度和水分影响较明显;40℃下试样放置24 d后的酸值和过氧化值分别达到1.03 mgKOH/g和19.2 meq/kg;Cu2＋对于葵花籽油过氧化值的影响大于Fe2＋;氧气短期内不会促进葵花籽油酸值的上升;添加了1%和2%水分的葵花籽油的酸值相差不大,均大于未加水样品,且水分含量越高,过氧化值增加越快。     

不同储藏方式对薏仁米储藏保鲜效果的影响

以兴仁薏仁米为实验材料,对其进行温度梯度、真空包装、降低水分含量及添加抗氧化剂处理,研究不同储藏方式对薏仁米水分含量、脂肪酸值和过氧化值的影响。结果表明:低水分含量储藏能显著抑制薏仁米脂肪酸值的升高,但对过氧化值的变化影响不大。抗氧化剂的添加提高了脂肪酸的含量,一定程度上抑制了过氧化值的升高,但对水分含量无显著影响,其中TBHQ效果最好,能将过氧化值控制在6.3 meq/kg以下。低于15℃的低温储藏和低温真空包装储藏是储藏薏仁米的有效方式,能在储藏过程中显著抑制脂肪酸值和过氧化值的升高并保持水分含量的稳定,可将薏仁米的储藏保鲜期由2个月延长为6个月或6个月以上。     

温度与水分对薏仁米贮藏过程中脂肪氧化的影响

以兴仁薏仁米为试验材料,探讨不同温度(15, 25和35℃)和水分(10.5%, 12.0%和13.5%)对薏仁米储藏过程中脂肪氧化的影响。结果表明,薏仁米的储藏温度和水分越高,其油脂氧化速率越快。180 d时,不同温度下薏仁米的脂肪酸值、过氧化值、电导率增加范围分别为182.84%～233.46%, 167.09%～314.01%和33.13%～74.02%,肪酶活动度下降范围为22.49%～47.69%,不同水分下其增加范围分别为87.60%～259.31%, 109.76%～254.66%和0.97%～15.15%。脂肪酸值和过氧化值受温度与水分的影响最显著;温度对电导率的影响大;温度与水分对丙二醛含量影响差异显著,与样品调节水分的前处理密切相关;与温度的影响相比,含水量高低对脂肪酶活性影响更大。低温与低水分能有效延缓薏仁米贮藏过程中的脂肪氧化。     

储藏温度对四川腊肉品质的影响

以常温(20℃)、冷藏(4℃)和冷冻(-18℃)3个不同储藏温度条件下储藏30天的腊肉为研究对象,分析储藏温度对pH、水分含量、脂质氧化、亚硝酸钠残留量以及组胺积累等的影响。结果表明:腊肉pH值随着贮藏温度的升高而降低,储藏温度20℃时,pH值降至5.48;水分的含量均下降,且储藏温度越高,水分含量降低幅度越大,20℃时水分含量减少30%;储藏温度越高,腊肉中的脂肪氧化程度越高;储藏温度对腊肉中亚硝酸盐的含量影响不显著(p0.05);20℃储藏时,腊肉中的组胺含量显著增加(p0.05),比低温储藏增加150%。     

干热处理对米糠储藏期脂肪酸、过氧化值及丙二醛变化的影响

米糠经不同干热处理后于25℃条件下储藏,研究不同储藏期米糠脂肪酸、过氧化值和丙二醛的变化。结果表明:随着储藏时间的延长,对照组和处理组脂肪酸值和丙二醛含量均显著增加;对照组过氧化值显著增加,而处理组过氧化值呈现先减小后增加的趋势。处理时间的延长和温度的增加有利于控制米糠的脂肪酸值,但处理时间过长会引起米糠储藏期过氧化值和丙二醛含量显著升高。     

初始水分含量与温度对油炸香蕉片贮藏稳定性的影响

为研究油炸香蕉片在不同贮藏条件下的贮藏特性,采用静态平衡将样品水分稳定到高、低两种初始水分含量,分别贮藏于0、25、37 ℃的避光环境,通过测定过氧化值、酸值、茴香胺值和介电常数等指标评价油炸香蕉片贮藏期间的氧化状况。结果表明,相同的贮藏温度和时间条件下,高初始水分含量油炸香蕉片的过氧化值、酸值、茴香胺值、介电常数均高于低初始水分含量的样品,降低油炸香蕉片的初始水分含量可以提高其贮藏稳定性。高初始水分含量油炸香蕉片的过氧化值随贮藏时间的延长而升高,低初始水分含量样品达到峰值后逐步降低;样品的酸值、茴香胺值在贮藏期间均升高;高初始水分含量样品介电常数在贮藏期间变化不大,低初始水分含量样品介电常数随贮藏时间的延长,整体呈上升趋势。     

氮气气调对不同水分含量大豆保鲜效果研究

研究了26 ℃条件下,不同水分含量（10%、12%、14%）大豆充氮气调（氮气浓度96%～98%）与常规贮藏60 d大豆品质指标和霉菌的变化情况。试验表明：充氮气调对抑制大豆发芽率下降,油脂酸值、过氧化值升高有一定效果。当大豆水分含量为10%,充氮对发芽率影响显著;当大豆水分含量为12%,充氮对发芽率、油脂过氧化值影响显著;当水分含量为14%,充氮对油脂过氧化值影响显著,对发芽率、油脂酸值影响极显著。充氮对大豆粗脂肪含量、霉菌菌落总数影响不显著。     

Characterization of the microbial community and its changes in liquid piglet feed formulations

The stability of the microbial populations in liquid piglet feed formulations was studied over a period of 3 months. Total aerobic bacteria, lactic acid bacteria, proteolytic bacteria, amylolytic bacteria, lipolytic bacteria, Bacillus cereus group and yeasts and moulds were monitored using selective media. The results demonstrated a tendency for slight increases in the numbers of total aerobic bacteria (p = 0.002), lactic acid bacteria (p = 0.014), proteolytic bacteria (p = 0.006) and lipolytic bacteria (p = 0.003). The numbers of amylolytic bacteria (p = 0.791) and yeasts and moulds (p = 0.620) were more variable, and Bacillus cereus‐like bacteria were nearly absent. Lactic acid bacteria, especially lactobacilli and leuconostocs, were the predominant population, indicating that a natural fermentation occurred, reducing the pH of the feeds to 4.7. The presence of proteolytic, lipolytic and amylolytic bacteria could theoretically lead to an improvement in the digestibility of the feeds. Copyright © 2004 Society of Chemical Industry     

Dietary restriction improved feed efficiency of inefficient lactating cows

The aim of this study was to reduce voluntary dry matter intake (DMI) to increase feeding efficiency of preclassified inefficient (INE) dairy cows through restricted feeding. We studied the effects of dietary restriction on eating behavior, milk and energy-corrected milk (ECM) production, in vivo digestibility, energy balance, and measures of feed efficiency [residual feed intake (RFI) and ECM/DMI]. Before the experiment, 12 pairs of cows were classified as INE. The 2 dietary treatments consisted of ad libitum feeding versus restricted feeding of the same total mixed ration containing 36.5% roughage. Inefficient cows fed the restricted total mixed ration had a shorter eating time and lower meal and visit frequency, but a similar rate of eating, meal size, and meal duration compared with INE cows fed ad libitum. Compared with the INE cows fed ad libitum, restricted INE cows had 12.8% lower intake, their dry matter and neutral detergent fiber digestibility remained similar, and their ECM yield was 5.3% lower. Feed efficiency, measured as RFI, ECM/DMI, and net energy retained divided by digestible energy intake, was improved in the restricted INE cows as compared with the ad libitum cows. Our results show that moderate DMI restriction has the potential to improve feed efficiency of preclassified INE cows.     

高速分件供送螺杆全程单函数运动规律及特性分析

根据分件供送工艺要求，用一种新方法推出了变螺距供送螺杆全程单函数运动规律。在计算机上分析了该运动规律的各特性函数及其图象，证明它是一种全程统一、自然连续、惯性冲击小、动力特性好且应用方便的优良运动规律。此外，还探讨了螺杆基本参数的变化规律。为变螺距供送螺杆理论和设计的发展，提供了新的途径。     

Breeding goal traits accounting for feed intake capacity and roughage or concentrate intake separately

Current breeding tools aiming to improve feed efficiency use definitions based on total dry matter intake (DMI); for example, residual feed intake or feed saved. This research aimed to define alternative traits using existing data that differentiate between feed intake capacity and roughage or concentrate intake, and to investigate the phenotypic and genetic relationships among these traits. The data set contained 39,017 weekly milk yield, live weight, and DMI records of 3,164 cows. The 4 defined traits were as follows: (1) Feed intake capacity (FIC), defined as the difference between how much a cow ate and how much she was expected to eat based on diet satiety value and status of the cow (parity and lactation stage); (2) feed saved (FS), defined as the difference between the measured and the predicted DMI, based on the regression of DMI on milk components within experiment; (3) residual roughage intake (RRI), defined as the difference between the measured and the predicted roughage intake, based on the regression of roughage intake on milk components and concentrate intake within experiment; and (4) residual concentrate intake (RCI), defined as the difference between the measured and the predicted concentrate intake, based on the regression of concentrate intake on milk components and roughage intake within experiment. The phenotypic correlations were ?0.72 between FIC and FS, ?0.84 between FS and RRI, and ?0.53 between FS and RCI. Heritability of FIC, FS, RRI, and RCI were estimated to be 0.21, 0.12, 0.15, and 0.03, respectively. The genetic correlations were ?0.81 between FS and FIC, ?0.96 between FS and RRI, and ?0.25 between FS and RCI. Concentrate intake and RCI had low heritability. Genetic correlation between DMI and FIC was 0.98. Although the defined traits had moderate phenotypic correlations, the genetic correlations between DMI, FS, FIC, and RRI were above 0.79 (in absolute terms), suggesting that these traits are genetically similar. Therefore, selecting for FIC is expected to simply increase DMI and RRI, and there seems to be little advantage in separating concentrate and roughage intake in the genetic evaluation, because measured concentrate intake was determined by the feeding system in our data and not by the genetics of the cow.     

微生物与酶制剂在秸秆发酵饲料生产中的应用

利用微生物的自身代谢活动与酶制剂而生产的发酵饲料正逐渐成为解决饲料紧张和环境问题的重要手段。微生物与酶制剂将难以直接消化吸收的农作物秸秆等原料转化成易被牲畜采食消化吸收的、营养价值更高且无毒害的发酵饲料。该文对发酵饲料的定义、在发酵饲料中应用的微生物与酶制剂和生产中存在的问题进行了阐述,并对微生物与酶制剂发酵饲料的进一步发展做了展望。     

Effects of forage presentation and addition of molasses-based liquid feed on dairy calf dietary selection and feed sorting of mixed diets

The objective of this study was to examine the effects of including a molasses-based liquid feed on sorting of a mixed diet of starter and hay, and to compare the nutrient composition of the ration consumed by calves offered hay and starter according to different feed presentations. Holstein bull and heifer calves were exposed for the first 8 wk of life to 1 of 3 feed presentation treatments: (1) starter and hay provided in separate buckets (n = 15), (2) a mixed diet of 80% starter and 20% hay (n = 16), or (3) a mixed diet containing the same ratio of starter and hay, with inclusion of 10% (as-is basis) liquid molasses (n = 14). Calves received 8 L/d of pasteurized waste milk and were weaned over a 10-d period beginning at 42 d of age. Intake was recorded daily and calves were weighed weekly. Fresh and refused feed were sampled on 3 consecutive days during wk 4 and 6 of the preweaning period and wk 8 immediately postweaning. Sorting was assessed through nutrient analysis of the feed samples, with additional sorting indices reflective of sorting for starter and hay components calculated based on weighted averages of individual nutrient intakes as a percent of predicated intakes. Dry matter intake and average daily gain did not differ among treatments. During the preweaning period, addition of molasses to the mixed diet did not affect the extent of feed sorting, with calves provided both mixed diets sorting, on average, in favor of starter and against hay. Postweaning, addition of molasses tended to reduce the extent of feed sorting, although calves on both treatments persisted in sorting for starter and against hay. Across treatments, there was an association between the pre- and postweaning extent of feed sorting, suggesting a degree of individual consistency in sorting behavior. Calves provided starter and hay separately consumed a diet consisting of approximately 18 to 19% hay preweaning and 14% hay postweaning, and generally had greater fiber intake and lower intake of nonfiber carbohydrates compared with calves provided a mixed diet. These results indicate that addition of molasses slightly reduced sorting during the postweaning period only. On average, calves provided both mixed diets sorted their feed in favor of starter and against hay, which mirrored dietary selection exhibited by calves offered hay and starter separately.     

Blood plasma traits associated with genetic merit for feed utilization in Holstein cows

The objective of this study was to evaluate the potential of selection for feed utilization on associated blood plasma metabolite and hormone traits. Dry matter intake (DMI) was recorded in 970 Holsteins from 11 commercial farms in Pennsylvania and used to derive dry matter efficiency (DME; fat-corrected milk yield/DMI), crude protein efficiency (CPE; protein yield/crude protein intake), and residual feed intake (RFI, defined as actual feed intake minus expected feed intake for maintenance and milk production, based on calculation of DMI adjusted for yield, body weight, and body condition score). Estimated breeding values for the 4 feed utilization traits (DMI, DME, CPE, and RFI), yield traits, body traits, and days open were standardized according to their respective genetic standard deviations. Up to 631 blood samples from 393 cows from 0 to 60 d in milk (DIM) were evaluated for blood plasma concentrations of glucose, nonesterified fatty acids (NEFA), β-hydroxybutyrate (BHB), creatinine, urea, growth hormone (GH), 3,5,3′-triiodothyronine (T3), and other parameters. Blood plasma traits were regressed on DIM, lactation number, herd, and standardized genetic merit. Cows with higher genetic merit for yield had significantly higher concentrations of GH, NEFA (milk and protein yield), and BHB (fat yield) from 31 to 60 DIM, but lower concentrations of glucose from 0 to 30 DIM, and T3 (milk yield, 0–60 DIM). The high GH–low glucose–low T3 concentration pattern was further accentuated for cows with genetic merit for enhanced feed efficiency (higher DME and lower RFI). Cows with a genetic tendency to be thin (low body condition score) also had elevated GH concentrations, but lower blood glucose, creatinine, and T3 concentrations. Those characteristics associated with enhanced feed efficiency (higher GH and lower glucose and T3 concentrations) were unfavorably associated with fertility, as indicated by elevated days open. Elevated NEFA and BHB concentrations were also associated with extended days open. Consideration of metabolic profiles when evaluating feed efficiency might be a method of maintaining high levels of health and reproductive fitness when selecting for feed efficiency.     

不同诱食剂对异育银鲫、奥尼罗非鱼作用效果的研究

以平均体重为84、6g的异育银鲫及27g奥尼罗非鱼鱼种为试验对象,进行了3个试验,考察DMPT、鱼溶肽蛋白、甜菜碱、甘氨酸、L-丙氨酸等的诱食效果。结果表明:在饲料中添加0.05%DMPT、0.1%DMPT、0.1%鱼溶肽蛋白、0.3%甜菜碱、1%甘氨酸、0.5%L-丙氨酸以及2%五味子汁对异育银鲫、奥尼罗非鱼均具有极显著的诱食效果(P<0.01)。     

Effect of feed delivery method on the behavior and growth of dairy heifers

The objective of this study was to determine the effects of feed delivery method on growth, feeding competition, feeding, and sorting behavior of dairy heifers. Thirty-two Holstein heifers (146.2 ± 21.9 d of age) were divided into 8 groups of 4 and exposed to 1 of 2 feed delivery treatments for 13 wk. The treatment rations contained 65% grass/alfalfa haylage and 35% textured concentrate (on a dry matter basis) fed as a 1) total mixed ration (TMR) or 2) top-dressed ration (TDR). Group dry matter intakes were recorded daily throughout the experiment. Feeding behavior, recorded using time-lapse video, and sorting behavior were measured for 7 d during each of wk 1, 5, 9, and 13. Sorting activity was determined through particle size analysis of the fresh feed and orts. The particle size separator separated feed into 4 fractions (long, medium, short, and fine). Sorting of each fraction was calculated as actual intake expressed as a percentage of predicted intake. Heifers were fecal scored for consistency of stool twice weekly using a scale from 1 (liquid) to 4 (solid); heifers were weighed every 2 wk. Neither dry matter intake (7.3 kg/d) nor average daily gain (1.3 kg/d) differed between treatments. Heifers fed the TDR tended to consume less neutral detergent fiber than heifers fed the TMR (4.77 vs. 4.91 kg/d). Heifers fed the TDR sorted against long particles (98.9 vs. 96.0%) and consumed short particles (100.3 vs. 101.1%) to a greater extent than did heifers fed the TMR. Daily feeding time did not differ between treatments (201.0 min/d), but heifers on the TDR did spend more time at the bunk in the 2 h following feed delivery (50.1 vs. 32.0 min/d). Heifers fed the TDR were displaced from the feed bunk more frequently than heifers fed the TMR (17.6 vs. 8.6 times/d), particularly during the 2-h period following feed delivery. Fecal scores were lower for heifers on the TDR (2.7 vs. 3.4). These results suggest that feeding a TMR to replacement dairy heifers may promote a more even diurnal feeding pattern, minimize feed sorting and feed bunk competition, and promote more solid fecal consistency.