VARIATIONS IN ALFALFA JUICE SOLUTE CONCENTRATIONS AS WATER IS EVAPORATED

Alfalfa juice was extracted from plants during the graving phases of the first and second crops. The alfalfa juice was dried and solute concentrations were measured periodically during the process using freezing point depression (FPD) as an indicator. Solute/solvent weight ratios were calculated from the freezing point depression of fresh unconcentrated 'uice extracted from both firsc and second crops. At the time of harvest, tie FPD was a function of this ratio. The first and second crops behaved distinctively different during the drying process, with the second having a larger soluce concentration and a greater FPD at a given moisture content. The appearance of preci itate during the drying process and the general1 large FPD makes this materiay a questionable product for drying vitg low temperature processes.     

Effect of excess boron fertilization on status and availability of boron in calcareous soils

Field experiments were conducted at Al-Qatif area in the eastern region of Saudi Arabia to study the status and availability of B under B fertilization regime in three types of calcareous soils and to evaluate the response of two alfalfa varieties, Hassawi (local variety) and Hyden (american variety), to increasing levels of added B.Boron was applied at 7 rates as Na₂B₄O₇.10H₂O. Four cuttings were taken from each site at different intervals. Data showed that extractable B by hot-water and NH₄HCO₃-DTPA (8 days after borax application) was significantly (p <0.001) affected by soil type and B applications. The amount of B recovered by hot-water from the three soils, 200 days after borax application, was in the following order: sandy loam > sandy clay loam > clay loam.Total dry matter of alfalfa (4 cuttings) was significantly (p <0.05) affected by soil type, borax application rates and alfalfa variety.The critical level of B in plant as determined by Cate and Nelson analysis, ranged from 148 to 652 mg kg^–1 dry matter for Hassawi cultivar and 138 to 521 mg kg^–1 for Hyden cultivar in the first harvest. However, the upper critical levels for the 2nd, 3rd and 4th harvests were 800, 875 and 935 mg B kg^–1 dry matter for Hassawi and 603, 723 and 812 mg B kg^–1 for Hyden varieties, respectively. Nevertheless, the lower critical levels for 2nd, 3rd and 4th harvests ranged from 148 to 153 mg B kg^–1 dry matter for Hassawi and 138 to 142 mg B kg^–1 for Hyden.     

苜蓿田杂草茎口叶处理药剂筛选试验报告

对5％普施特AS、25％苯达松AS、50％高特克SE、15％精稳匀得EC、6．9％威霸EW等10种除草剂及其混用在苜缩中进行了药效试验。除草效果达到80．7％－98．2％，增产效果显著。     

热处理工艺对45＃钢抗苜蓿草粉的磨损性能影响

苜蓿草粉对环模系统的磨粒磨损是造成饲料制粒机关键部件失效的主要原因。为提高环模系统关键部件材料的抗磨粒磨损性能,采用不同热处理工艺对45#钢热处理,在磨粒磨损试验机上考察其抗苜蓿草粉的磨损行为,用金相显微镜对试样的金相组织进行分析研究,用扫描电镜对试样摩擦表面的磨损形貌进行观察研究。结果表明：经淬火处理后45#钢的磨损主要表现为显微切削和机械抛光,未见明显的塑性疲劳;当材料的硬度提升至一定值时,通过硬度与韧度的合理配合可获得较好的抗植物磨料磨损性能;相对于常温淬火,45#钢亚温淬火后抗植物磨料磨损性能明显提升。     

Use of exogenous fibrolytic enzymes to enhance in vitro fermentation of alfalfa hay and corn silage

Two in vitro experiments were performed to identify promising exogenous fibrolytic enzyme products (EFE) and optimum dose rates (DR) for improving the degradation of alfalfa hay and corn silage. The relationship between enzymatic activity and fermentation responses was examined to identify optimum formulations. In experiment 1, 5 EFE containing mainly endoglucanase and xylanase activities, with different ratios between the 2 activities, were assessed at a DR of 0.7, 1.4, and 2.1 mg/g of DM forage. Milled alfalfa hay or corn silage was incubated in an in vitro batch culture with buffer, ruminal fluid, and EFE. Gas production (GP) was measured during 24 h of incubation, and degradabilities of DM and fiber were measured after terminating the incubation at 24 h. Two (E1 and E3) EFE substantially improved GP and degradation of alfalfa hay and corn silage fiber. The optimum DR of these EFE was 1.4 mg/g of DM for both forages with improvements in NDF degradability up to 20.6% for alfalfa hay and up to 60.3% for corn silage. Whereas added activities of endoglucanase and exoglucanase were positively correlated with improvement in NDF degradability for alfalfa hay and corn silage, there was no relationship between added xylanase activity and NDF degradability. The 2 most promising EFE from experiment 1 were reevaluated in experiment 2, alone and in combination with a high xylanase EFE, to determine whether their effectiveness could be enhanced by decreasing the endoglucanase to xylanase ratio. The 2 EFE improved GP and fiber degradation in a manner similar to that observed in experiment 1, but the combination treatments resulted in no further beneficial effects. Exogenous fibrolytic enzyme products can greatly improve forage utilization, but DR and the activities supplied are critical for achieving this response. Products used with alfalfa hay and corn silage should contain high endoglucanase activity, with an ideal ratio of endoglucanse to xylanase.     

Efficacy of carbohydrate sources for milk production by cows fed diets based on alfalfa silage

The effectiveness of three carbohydrate sources, high-moisture ear corn (HMEC), cracked shelled corn (CSC), and a 50:50 mixture of HMEC plus dried citrus pulp (DCP), fed with or without supplemental rumen-undegraded protein as expeller soybean meal (ESBM), was assessed in 48 multiparous dairy cows. All diets contained (dry mater [DM] basis) 50% alfalfa silage, 10% ryegrass silage, 28% NDF, and one of six concentrates: A) 38% HMEC; B) 38% CSC; C) 19% DCP plus 19% HMEC; D) 27% HMEC plus 12% ESBM; E) 27% CSC plus 12% ESBM; or F) 13% DCP, 13% HMEC, and 12% ESBM. Diets A, B, and C averaged 19% crude protein, of which 53% was nonprotein nitrogen (NPN), and diets D, E, and F averaged 22% crude protein, of which 40% was NPN. Cows were fed a high-energy covariate diet for 2 wk, blocked into eight groups of six, based on covariate protein yield, then randomly assigned to diets that were fed for 12 wk. Feeding ESBM increased DM intake, yields of milk, fat-corrected milk, fat, protein, SNF, and milk and blood urea concentration and decreased weight loss. There were no production differences between HMEC and CSC. However, DM intake, yields of milk, fat-corrected milk, fat, protein, lactose, SNF, and milk SNF content all were lower on the diets containing DCP versus HMEC and CSC. A 6 x 6 Latin square trial conducted at the same time with six ruminally cannulated cows showed similar effects of diet on DM intake and milk production. Ruminal ammonia was elevated by ESBM but not ruminal total amino acids and branched-chain volatile fatty acids. Ruminal propionate was highest on HMEC diets and lowest on DCP diets; acetate, butyrate and acetate-to-propionate ratio were lowest on HMEC diets and highest on DCP diets. These results indicated that, compared to HMEC and CSC, feeding the pectin-rich carbohydrate source DCP altered ruminal fermentation but depressed intake and milk production in lactating cows.     

Glandular Trichome Extracts from Medicago sativa Deter Settling by the Potato Leafhopper Empoasca fabae

Extracts of glandular trichomes from Medicago sativa were tested for their ability to disrupt the settling behavior of the potato leafhopper, Empoasca fabae. Erect and procumbent glandular trichomes were mechanically isolated from stem sections of resistant genotype "G98A," and nonglandular trichomes were collected from susceptible cultivar "Ranger." Isolated trichomes were extracted with chloroform, acetone, and ethanol, and the resulting crude extracts were applied to the surface of a sachet containing an artificial diet. Leafhoppers were offered a two-way choice between crude trichome extracts from G98A and Ranger. All three of G98A solvent extracts caused various degrees of diet rejection, resulting in the crude Ranger trichome extracts being preferred over G98A extracts. Overall, the fewest leafhoppers settled on the ethanolic extracts. Additional bioassays documented a dose response associated with G98A ethanolic extracts when compared with Ranger trichome extracts and a solvent control. No difference in preference behavior was detected between Ranger trichome extracts and a solvent control. Gas chromatography-mass spectrometry analysis revealed a homologous series of nonvolatile fatty acid amides C(n)H(2n+1)NO (n = 19-23) unique to G98A glandular trichome extracts.     

Effect of quantity,quality, and length of alfalfa hay on selective consumption by dairy cows

Twenty-four lactating Holstein cows were used in a replicated 6 x 6 Latin square design. Experimental periods were 6 or 7 d. Cows were housed in tie-stalls, and diets were fed ad libitum twice daily at 1100 and 1600 h. Diets contained 60% concentrate and either 40% alfalfa hay or 20% alfalfa hay and 20% alfalfa silage (dry matter basis). The effect of quantity, quality, and length of hay on sorting behavior was determined. Treatments consisted of 20% lower or higher quality long alfalfa hay, 20% lower or higher quality chopped alfalfa hay, and 40% lower or higher quality chopped alfalfa hay. Variation of sorting among cows was also determined. Particle size distribution of samples of as-fed total mixed rations and orts were determined using the Wisconsin particle size separator. Screens have square holes with diagonals of 26.9, 18, 8.98, 5.61, and 1.65 mm (screens Y1 to Y5, respectively). Sorting was calculated as the actual intake of each fraction expressed as a percentage ofthe predicted intake. Increasing the proportion of dry hay increased sorting. Quality of alfalfa hays that were offered did not affect sorting activity. Feeding long alfalfa hay increased selective consumption of fine particles. However, feeding long alfalfa hay also increased intake of longer particles because a higher percentage of long particles was offered. Across treatments, animals consistently sorted against longer particles in favor of finer particles. In particular, intake of Y1 as a percentage of the predicted intake was the most variable. Average Y1 intake, across the six treatments for each cow, was between 60 and 70% of predicted intake for four cows, 71 to 80% for 11 cows, 81 to 90% for five cows, 91 to 100% for two cows, and 101 to 110% for two cows. On one diet a cow failed to consume any of the Y1 portion of the total mixed ration. This variation among animals in sorting of very long feed particles may have practical significance.