PART I. EVALUATION OF FOUR CULTIVATED TROPICAL PASTURES AND THREE BREEDS OF CATTLE FOR INCREASED BEEF PRODUCTION AND PART II. DIGESTIBILITY OF ALFALFA HAYLAGE, SODIUM-HYDROXIDE-TREATED AND UNTREATED WHEAT SILAGES BY LAMBS.

摘要

Part I. A put-and-take grazing trial was conducted at Pichilingue/INIAP, Ecuador (March, 1980 to February, 1981), with yearling Brahman, 1/2 Brahman x 1/2 Holstein, and Criollo bulls grazing Common Guinea (Panicum maximum Jacq.), Improved Guinea (Panicum maximum, cv. Pichilingue), Improved Guinea + Glycine wightii, and Brachiaria humidicola pastures.;The phases in cattle weight changes were: Gain (March to October), maintenance (early November), loss (November to early January), and gain (January to February). The mean maximum values for these phases were 700, 18, -398, and 1,070 g/day, respectively. The ranges in beef production (kg/ha) and carrying capacity (animal days/ha) were 179 to 247 and 509 to 557, respectively. The lowest values were from the mixture, the highest, from Improved Guinea. Average daily gain (g/day) were: Brahman, 411; 1/2 Brahman x 1/2 Holstein, 432; and Criollo, 314. Nutrient composition of seven weed species was determined. Two weeds, Alternanthera guellensis and Amaranthus spinosus, were grazed by cattle during the DS.;Part II. Two digestion trials using lambs compared five forage treatments: (1) untreated wheat silage (WS), (2) NaOH-treated WS, (3) alfalfa haylage, (4) 1/2 untreated WS + 1/2 haylage, and (5) 1/2 NaOH-treated WS + 1/2 haylage. Forage ratios were on a DM basis. Diets were 12% CP and about 88% forage and 12% supplement, DM basis. NaOH-treated WS underwent clostridial fermentation; untreated WS, lactic acid fermentation.;In vivo DM digestibilities (DMD) of diets containing forage treatments 1 to 5 were 61.5, 65.9, 60.6, 60.3 and 60.5% (Trial I); and 69.1, 69.9, 66.3, 66.5 and 67.5% (Trial II). In Trial II, NaOH increased in vitro DMD of WS by 3.15% and in vivo DMD by only .8%. Lambs fed NaOH WS consumed more DM, but had lower CP and energy digestibilities and N retention than those fed untreated WS. Improvements from NaOH treatment did not justify the cost of the alkali and hazards involved in its application to WS.;From the wet season (WS) to the dry season (DS), a dry matter (DM) yields, crude protein (CP), and in vitro DM digestibility (IVDMD) declined while cell wall contents, except cellulose, increased. Mineral contents did not change seasonally. Ranges in mean values were: DM yield (Brachiaria, 2,033 to the mixture, 2,994 kg/ha); CP (Brachiaria, 9.8 to the mixture, 12.8%); and IVDMD (Common Guinea, 54.7 to Brachiaria, 57.5%).