The current study was undertaken to evaluate the effects of feeding timothy (Phleum pratense L.) hay differing in dietary cation-anion difference (DCAD) on the capability of cows to maintain calcium homeostasis around parturition. We hypothesized that feeding low-DCAD timothy hay during the prepartum period would induce a mild metabolic acidosis prepartum and improve calcium homeostasis postpartum with no effect on dry matter intake. Forty-one dry pregnant Holstein cows entering their second lactation or greater were used in a randomized complete block design. Timothy hay was obtained from an established timothy stand under a pivot irrigation system. Low-DCAD timothy hay was produced by fertilizing the area between the second and third pivot towers at a rate of 224 kg of CaCl(2)/ha, and control timothy hay (high DCAD) was grown on the area between the fourth and fifth pivot towers of the same field. The chloride concentration was 1.07 and 0.15% on a dry matter (DM) basis, and the DCAD was 1.2 and 21.6 mEq/100 g of DM for the low- and high-DCAD timothy hay, respectively. Experimental diets, containing timothy hay at 63% of dietary DM, were fed ad libitum starting 30 d before the expected calving date. The DCAD values were 1.6 vs. 14.5 mEq/100 g of DM for the low- and high-DCAD timothy-based diets, respectively. At the beginning of the study, urine pH and blood bicarbonate concentration averaged 8.22 +/- 0.06 and 28.5 +/- 0.3 mM, respectively. The low-DCAD timothy diet decreased urine pH compared with the high-DCAD timothy diet on d 21 (7.75 vs. 8.31), d 14 (7.69 vs. 8.22), and d 7 (7.50 vs. 8.19) before calving, and it also decreased the prepartum blood bicarbonate concentration by 2 mM. In addition, cows fed the low-DCAD timothy diet had greater blood ionized calcium concentration prepartum (1.22 vs. 1.19 mM), greater blood ionized calcium concentration at 0 and 8 h after calving, and similar prepartum dry matter intake. These results indicate that timothy hay differing in DCAD affects the acid-base balance of periparturient dairy cows, and that low-DCAD timothy hay improves calcium homeostasis postpartum with no negative effect on dry matter intake.
. 2009. Effect of irrigation management on yield, and water use efficiency of timothy hay in southern Alberta. Can. J. Plant Sci. 89: 1075Á1088. Timothy hay production for export markets has recently expanded on the Canadian prairies. Irrigation management information for timothy production is limited; therefore, irrigation practices to achieve optimum dry matter (DM) yield and water use efficiency (WUE) of timothy hay were investigated from 2005 to 2007 near Bow Island and Picture Butte, Alberta. Treatments were defined by managing irrigation using 0.25-m, 0.50-m, 0.75-m, and 1.00-m root zone depths with an allowable moisture depletion of 50% of available soil moisture. The 0.25-m root zone treatment resulted in greater first-cut timothy DM yield than the 1.00-m root zone treatment at Bow Island. The 0.50-m root zone treatment resulted in greater first-cut timothy DM yield than the 0.25-m root zone treatment at Picture Butte. Treatment effect on the second-cut DM yield was not significant. Water use for the first-cut crop was significantly greater for the 0.25-m root zone treatment at Bow Island and for the 0.50-m root zone treatment at Picture Butte than the other treatments in 2006 and 2007. There was no consistent treatment effect with the second-cut crop water use. The treatment effect with the first-cut WUE was not significant and there was no consistent treatment effect with the second-cut WUE. Use of a shallow root zone depth (0.25Á0.50 m) for irrigation management could optimize first-cut timothy production for export, but producers may need to avoid irrigating the second-cut crop to conserve water for other efficient uses in southern Alberta.
R. 2009. Yield and quality responses of irrigated timothy to fertilizer application in southern Alberta. Can. J. Plant Sci. 89: 247Á255. Timothy (Phleum pratense L.) hay production for export markets has expanded considerably in western Canada during the past decade. Fertilization practices for optimum yield and quality of irrigated timothy were investigated for 4 yr at two locations in southern Alberta. The efficacy of spring-broadcast urea and ammonium nitrate (AN) were similar and greater than that of controlled-release urea. The optimum N rate for dry matter yield was approximately 130 kg N ha(1 for the first cut and 110 kg N ha(1 for the second cut, depending on crop and fertilizer prices. Both green colour and brown leaf ratings increased with N rate, with optimum colour for the first cut obtained with 100 to 150 kg N ha (1 . Digestibility was unaffected by N rate except when crops were very deficient in N. At the location where timothy was responsive to P fertilization, yields were similar with annual broadcast applications of 13 kg P ha(1 or one pre-seeding application of 86 kg P ha (1 . Timothy yield and quality were not responsive to K fertilization, although high K removal rates may shorten the period until K deficiencies develop. High yields of timothy hay (average 11 Mg ha(1 yr(1 ) were consistently obtained with adequate N and P fertilization.
Project IICE was a multi-disciplinary learning experience designed for students at Southern New Hampshire University. Students worked together in teams to communicate scientific data that was initially collected by an Introductory Botany class. Students in this course measured trees and recorded variables, including tree height, diameter, species, and canopy cover. They shared the data with students in freshman Statistics courses, who analyzed mathematically for trends. Finally, students in Graphic Design used the data to create visual representations and icons. Students collaborated in groups that were randomly assigned across all of the courses to include members of each discipline. During the process, each student was required to help others in the group understand the meaning of the data, through the collection, analysis, and design phases. In the final group poster presentations, students explained the meaning and value of each part. The emphasis was on their ability to communicate the significance of each part of the process, which helped them appreciate how the discipline they were working in contributed to the overall success of the project. The real-world data provided a context for students to experience working in cross-discipline teams, and sharpened communication skills.
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