Three experiments carried out in the southeast of Mexico (Yucatan) are reported. In the first, yield of P. purpureum increased from 3,760 to 14,526 kgDM/ha with age 6 weeks (young) and 28 weeks (mature). Maturity increased lignin from 43 to 108g/kgDM. Potential degradabilities of leaf and stem were 788g & 782g/kgDM with young, and 725 & 403g/kgDM with mature. Young yielded more potentially degradable DM (70 & 35kgDM/ha/d) than mature. In the second, molasses urea block (MUB) supplementation of bulls grazing during the dry season, did not improve the potential degradability of pasture (525g/kgDM). Estimated pasture intake was 68gDM/kgW0.75 /d, and measured rumen pool size of grazing bulls was 79 gDM/kgW 0.75. Intake of MUB was low (236gDM/d) and only increased rumen NH 3-N from 100 to 128mg/l. Availability of pasture was 255kg DM/animal. It is suggested that need of supplementation could be low if there is sufficient pasture to allow selective grazing. In the third, hay diets of young or mature P. purpureum were studied in six zebu (Bos indicus) bulls fed ad libitum. Intakes were, 91 and 44gDM/kgW0.75/d, digestibilities, 591 and 453g/kgDM, estimated energy intakes 768 and 307kJME/kgW0.75/d and Metabolizable Protein, 4.1 and 1.3g/kgW0.75/d with young and mature forages respectively. Forage maturity resulted in negative N balance (352 vs -113mgN/kgW0.75/d), decreased potential (756 vs 568g/kgDM) and fractional rate (0.07 vs 0.03%) of rumen DM degradation, but gave higher DM degradabilities of the non-soluble fraction (378 vs 283g/kgDM). Forage maturity reduced rumen outflow rates of liquid (0.09 vs 0.05%), and solid (0.038 vs 0.015%) phases, increasing mean retention times of digesta (22 vs 65h), and the rumen pool size (84 vs 120gDM/kgW0.75) and reduced the eating (380 vs 273min) and rumination daily times (433 vs 398min). The Purine Derivatives (PD) excretion in urine reflected differences between diets (651 vs 354mMol/kgW0.75/d). However, rumen Microbial N Supply estimated by the PD method was very low in comparison with estimates from digestibility and N balance measurements. It is suggested this effect could be explained by greater recycling of PD to the rumen and a lower endogenous excretion by zebu cattle.

Thesis (MTech (Agriculture))--Cape Technikon, 1998. / The drymatter - and animal production of nine lucerne cultivars were evaluated under dryland conditions with SA Mutton Merino sheep at Outeniqua Experimental Farm (George). The nine lucerne cultivars that were chosen for this experiment, were already evaluated in cutting trials for their drymatter production. They consist of one winterdormant cultivar (Alfagraze), two semi-winterdormant cultivars (WL 320 and Meteor), five intermediate-winterdormant cultivars (SA Standard, Standard Tygerhoek, Aurora, Diamond and WL Southern Special) and one winteractive cultivar (Cuf 101). The mild climate of this area resulted mainly in a difference in drymatter production between the most winterdormant cultivar (Alfagraze) and winteractive cultivar (Cuf 101). The only difference in the rate of production of winterdormant types appear in winter and spring. The production rate of the winterdormant and semi-winterdormant cultivars was lower in the winter than that of the intermediate winterdormant (WL Southern Special) and the winteractive cultivar (Cuf 101). The drymatter production of the semi-winterdormant cultivar (WL 320) was higher than that of the winteractive cultivar (Cuf 101) in spring. There is a seasonal difference in the drymatter production of lucerne cultivars from the same winterdormancy class. Some of the more winterdormant cultivars also achieve a comparable and even higher dry matter production than that of the more winteractive cultivars. This tendancy is prominant between the semi-winterdormant cultivars (WL 320 and Meteor). WL 320 has a higher dry matter production than Meteor. It also has a higher or equal production rate, dependant on the seasons, than the winteractive cultivar (Cuf 101). A similar tendancy appears in the intermediatewinterdormant cultivar (WL Southern Special). The seasonal drymatter production and production rate of this cultivar are the same as that of Cuf 101. The appearance of annual grasses and weeds had a seasonal influence on the availability of dry matter and animal production. The grass production increases over the years resulting in up to 20% increase of the green matter during winter and spring. The grazing capacity of the winterdormant cultivar (Alfagraze) has increased during this seasonal grass production. The lucerne cultivar with the highest drymatter production rate and the highest seasonal dry matter production, also had the highest grazing capacity. The yearly and seasonal grazing capacity of WL 320, Aurora, WL Southern Special and Cuf 101 was generally higher than most of the other cultivars. This was also the most important reason for the high live mass increase with these cultivars.

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Thesis (M.S. in environmental science)--Washington State University, December 2009. / Title from PDF title page (viewed on Jan. 22, 2010). "School of Earth and Environmental Science." Includes bibliographical references (p. 18-23).

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