猪肌肉糖原酵解潜力的影响因素及其营养调控研究进展

肌肉糖原酵解是屠宰后肌肉向肉转变过程中的主要能量代谢途径,产生的乳酸和H+会降低肉的pH、改变蛋白质变性程度,与肉色、系水力、嫩度密切相关,对肉品质形成有重要作用。肌肉糖原酵解潜力可反映糖酵解的程度与速率,是肉品质评价的重要指标之一。本文综述了猪肌肉糖原酵解潜力的影响因素及其营养调控途径,为肉品质调控提供理论依据。     

2种盐生植物饲用价值的研究

为探讨狐米草(Spartina patens)和北美海蓬子(Salicornia bigelovii)的养分含量动态变化趋势,从2009年6月到10月分别取样后,测定了二者的干物质(DM)、粗蛋白(CP)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)、干物质体外消化率(IVDMD),以及钙、磷、钠含量。结果表明:狐米草在6月份的营养价值最高,矿质元素含量合理,以后有所下降,因此可在6月时对其进行合理的开发应用,而从6月到10月海蓬子的营养价值逐渐下降,但是在10月海蓬子干物质含量相对较高,同时钠含量较低,钙磷比较合理,所以从牧草利用的角度建议在10月对其进行开发利用。     

Fecal pH and Microbial Populations in Thoroughbred Horses During Transition from Pasture to Concentrate Feeding

Abrupt dietary transitions and feeding of rapidly fermentable diets are common practices in the horse industry and have been associated with digestive and metabolic disorders that can impair the performance of horses. The present study investigated the effect of dietary transition from pasture grazing to confinement with concentrate feeding, and back, on fecal pH and bacterial populations of Streptococcus spp and Lactobacillus spp. Six Thoroughbred fillies, previously grazing perennial ryegrass and white clover-based pasture, were housed in individual stalls and fed an increasing ratio of concentrate to conserved forages for 13 days (days 1-13), followed by an abrupt transition back to only pasture-grazing for 3 days (days 14-16). The concentrate was initially offered at 0.83 kg dry matter (DM)/d and increased to 5 kg DM/d, whereas ensiled alfalfa was initially offered at 0.61 kg DM/d, increasing to 1.22 kg DM/d. Meadow hay was initially offered at 6.73 kg DM/d, decreasing to 1.6 kg DM/d. Fecal specimens were collected daily for determination of pH, and every 2 days for quantitative analysis of Streptococcus spp and Lactobacillus spp. Mean fecal pH increased significantly from pasture baseline values (pH 6.18) during the initial confinement and supplementation on day 1 (6.37), day 2 (6.52), day 3 (6.58), and day 4 (6.43) (standard error of mean [SEM]: 0.056; P < .001). By day 5, mean fecal pH values had decreased to, and remained at, baseline values until the horses returned to pasture, when another increase occurred at day 15 (6.45). Fecal colony forming units (cfu) of Streptococcus spp and Lactobacillus spp increased linearly (r = 0.94; P < .001) from 6.0 and 6.1 log₁₀ cfu/g on day -4, to 7.8 log₁₀ cfu/g on day 14 (SEM: 0.2 P < .001), respectively. Fecal cfu decreased on return to a pasture-only diet (P < .001). In this study, the increment of bacterial populations was associated with a relatively stable fecal pH and highlights the difficulty in identifying the effects of dietary transition on the equine hindgut health, without microbial culture.     

Effect of different dietary ratios of sunflower and linseed oils on growth and carcass traits of rabbits

As part of an experiment aiming to modify the meat fatty acid profile, this work studied the growth and carcass traits as affected by various dietary ratios of sunflower oil and linseed oil. A diet without added oil served as a control (C). Four other diets were equally 4% oil-enriched but they differed in the incorporation ratios of sunflower oil (S) to linseed oil (L), i.e. 4% S to 0% L (diet 4%S), 3% S to 1% L (diet 3:1%SL), 2% S to 2% L (diet 2:2%SL) and 0% S to 4% L (diet 4%L). The oil-rich diets had slightly higher digestible energy contents (11.4 vs 10.6 MJ/kg) than the C feed. In each group 10 litters of 7 to 9 Pannon White kits per litter were studied in the pre-weaning period from 21 to 35 days old. Growth and slaughter traits were assessed with 50 and 30 rabbits per group, respectively. No significant effects of diets were found on litter and doe performances. The only significant differences in growth performance of the C, 4%S, 3:1%SL, 2:2%SL and 4%L rabbits were for the 35–49 day feed intake (88, 86, 84, 84 and 83 g per day, respectively, P = 0.046), the 35–84 day growth rate (36, 38, 37, 35 and 37 g/day, P = 0.034) and the 84-day body weight (2608, 2703, 2664, 2565 and 2628 g, respectively, P = 0.022). There were several significant differences in carcass traits including the weight of reference carcass (1357, 1391, 1388, 1380 and 1369 g, respectively, P = 0.004) and left longisimus dorsi meat (78, 79, 81, 81 and 76 g, respectively, P = 0.046) of rabbits. The diets had major effects on the L*, a* and b* colour values (lightness, redness and yellowness) of meat and fat. Carcass colour of the C and 4%S rabbits was closer and the 4%L rabbits was further from the European consumer's preference of light coloured, less red and slightly yellow rabbit meat. Our result reveals the importance of age and body weight at slaughter. Taking the growth and slaughter performances and, the recent belief of human health benefits from lower n− 6/n− 3 FAs dietary ratios into account, the 2:2%SL diet seems most appropriate if the interests of the raisers, meat processors and buyers are considered equally.     

自由放养下绵羊的营养参数

根据绵羊的营养参数和饲养标准,结合日增重水平,计算了不同日增重水平对应的体重月平均动态及其所对应的粗蛋白日需要量和代谢能日需要量。不同日增重水平,达到生长期望所需要的日数不同,日增重水平越高,达到生长期望总所需要的粗蛋白和代谢能越少,但月平均的日需要量越多。自由放养的东北细毛羊当年生羔羊的日增重水平仅相当于舍饲饲养日增重的100g水平,根据代谢能计算,年总需干草340kg,可以作为计算载畜量的基本参数。自由放养情况下,即使能量满足需要,粗蛋白也短缺。当年生羔羊日增重在150￣200g,9￣10月龄内体重达到46￣50kg是北方草地家畜生产的理想目标,通过补饲可以实现。     

Effect of nutrition during calfhood and peripubertal period on serum metabolic hormones, gonadotropins and testosterone concentrations, and on sexual development in bulls

The objective of the present study was to characterize the effects of nutrition on circulating concentrations of metabolic hormones, gonadotropins, and testosterone during sexual development in bulls. Nutrition regulated the hypothalamus-pituitary-testes axis through effects on the GnRH pulse generator in the hypothalamus and through direct effects on the testes. Pituitary function (gonadotropin secretion after GnRH challenge) was not affected by nutrition. However, nutrition affected LH pulse frequency and basal LH concentration during the early gonadotropin rise (10-26 weeks of age). There were close temporal associations between changes in insulin-like growth factor-I (IGF-I) concentrations and changes in LH pulse frequency, suggesting a role for IGF-I in regulating the early gonadotropin rise in bulls. The peripubertal increase in testosterone concentration was delayed in bulls with lesser serum IGF-I concentrations (low nutrition), suggesting a role for IGF-I in regulating Leydig cell function. Serum IGF-I concentrations accounted for 72 and 67% of the variation in scrotal circumference and paired-testes volume, respectively (at any given age), indicating that IGF-I may regulate testicular growth. Bulls with a more sustained elevated LH pulse frequency during the early gonadotropin rise (high nutrition) had greater testicular mass at 70 weeks of age relative to the control group (medium nutrition), despite no differences in metabolic hormone concentrations after 26 weeks of age. Therefore, gonadotropin-independent mechanism regulating testicular growth might be dependent on previous gonadotropin milieu.     

解决夏季母猪“饥而不饿”的营养招数

夏季来临,温度是影响猪群健康的第一要素,尤其对于母猪,在高温下其对营养的吸收利用及代谢均会发生改变,导致母猪代谢不畅而不愿采食,这将严重影响猪群健康及繁殖成绩。文章将从营养调节角度分析,并结合生产实践来解决这一问题,以期为猪场夏季母猪健康养殖提供借鉴和参考。     

Experimental studies on the impact of an increased dose of anionic salts on the metabolism of dairy cows

Summary

This study was initiated to investigate the influence of a daily dose of anionic salts (AS) above the valid upper limit at present on metabolism of dairy cows. Eleven non‐pregnant and non‐lactating Holstein‐Friesian crossbred cows with a permanent rumen cannula were used in a study with a controlled feeding design. The initial daily dose was 2500 meq/day, which resulted in a Dietary Cation Anion Difference (DCAD) of ‐211 meq/kg dry matter. Every seven days, the daily dose was raised by 500 meq. If a cow stopped eating, the application of AS was stopped and these cows were monitored over the next seven days. On day 30 another batch of hay, having the same DCAD but higher concentrations of minerals and energy, was fed. Blood and urine samples were taken to monitor acid‐base balance and calcium concentrations. Acid‐base balance was strongly influenced by AS. Blood pH dropped steadily and reached values around 7.23. Urine pH dropped quickly below 6 and remained at that level regardless of the increased dosage of AS. Net acid base excretion (NABE) fell continuously with the increase of the dosage of AS and reached values below ‐200 mmol/l. Calcium concentrations in the serum were nearly stable, but those in urine increased sharply and remained on an elevated level with increasing doses of AS. A few days before the individual cow's refusal of feed intake, calcium excretion in urine decreased. The majority of cows stopped eating while consuming a diet containing 3500 to 4000 meq AS except two animals who consumed up to 6000 meq/day AS but they received the better hay in the second half of the treatment period. In this time pH in blood increased slowly. NABE remained stable on a low level at ‐100 mmol/l. The results showed that with an increasing amount of AS fed the risk of clinical acidosis increased. The decreasing urine concentrations of calcium indicate a breakdown of the compensation capability of the single cow. Besides the dose of AS fed, the quality of the feed stuff might be another factor concerning the tolerance of cows against AS.     

青刈黑麦产草量与营养动态分析

青刈黑麦在黄淮海地区具有广阔的发展前景。本文针对棉花冬闲田,对青刈黑麦在不同生育阶段的产草量、营养成分含量、刈割时间及刈割次数进行研究。结果表明,一次利用时,刈割时间不能超过抽穗后期。两次利用时,头茬刈割时间不能超过拔节期,二茬应在抽穗后期刈割。后者草的质量优于前者,但产草量较低,因此在实践中可根据需要决定刈割次数。     

20份紫花苜蓿在上海崇明地区的综合适应性研究

对20份紫花苜蓿(Medicago sativa)品种(系)在上海崇明地区的综合适应性进行评价比较,测定并分析了生育周期和株高、生长速度、草产量4项田间生长特性,并研究了裹包青贮苜蓿产品的粗蛋白、ADF、NDF等营养指标。结果表明:20份供试材料在上海崇明的生育期为185~191d;不同供试材料的田间生长特性存在差异(P0.05),株高表现为第二茬第三茬第一茬第四茬第五茬,生长速度表现为第二茬第三茬第五茬第四茬第一茬,草产量表现为第一茬第二茬第四茬第三茬第五茬;品种Super7的株高和生长速度在5次刈割时都明显高于其他试验材料,其累计株高为325.23cm,累计生长速度为每天6.36cm,丰宝累计草产量最高为61100.37kg·hm-2;20份供试材料随着刈割时间的变化,不同品种间的粗蛋白、ADF和NDF存在显著性差异(P0.05),猎人河平均蛋白含量最高达到18.82%,赛迪的RFV高达139.58%。综合评价结果显示,WL903、游客和Super7在上海地区的适应性和饲用价值较优,有推广的潜力。