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|Title:||A Critical Analysis of Tropical Savanna Forage Consumption and Utilization by Goats|
|Author(s):||Mccammon Feldman, Beth|
|Department / Program:||Animal Science|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Subject(s):||Agriculture, Animal Culture and Nutrition|
|Abstract:||Goats are important producers of meat, milk and fiber in many tropical countries, yet little is known about their adaptation to the utilization of the dry, scrubby vegetation found in these areas. This study was designed to evaluate goats' ability to use this type of vegetation and their productive capacity in tropical environments. Field experiments were carried out in Managua, Nicaragua from January to December, 1976. The study site was located at latitude 12 6' 23 N and longitude 86 8' 25 W. The climate consists of distinct wet and dry seasons with an average temperature of 28 C, varying little throughout the year. Rainfall averages 1180 mm per year and falls between May and October. Observed forage choice by the goats was not directly related to availability; browse species were extensively utilized. Results of stall-fed trials, esophageal fistula samples and total fecal collections of free-ranging animals gave an average dry matter intake estimate of 2.2% of body weight. At this intake level, true digestible organic matter of forage consumed must be 75% to achieve maintenance. Average in vitro true digestibility of hand-plucked samples of Jaragua grass was higher than the combined browses in the wet season (79.3% vs. 77.4%) but lower in the dry season (69.4% vs. 75%). In dry season feeding trials, apparent organic matter digestibilities of two representative browse species were greater than Jaragua grass (48.2% and 52.5% vs. 43.1%). Protein level limited intake of dry season Jaragua grass to 1.3% of body weight. Year-round low cell wall and adequate protein content of the browse species are the basis of their feeding value. Goats ate grass in the wet season when its cell wall digestibility was high but switched to browses when their over-all digestibility was superior. The goat is an opportunist feeder with the ability to utilize a broad range of plant materials.
Free-ranging goats under the conditions of this study without feed supplementation maintained a constant body weight throughout the year. Kidding percent was 222 for Nubian crossbreds and 154 for local goats. Kiddings occurred throughout the year although birth weight was lower at the end of the dry season. Average age at first kidding was 66.4 weeks. Kidding interval was 318 days for Nubian crosses and 331 days for local goats. Average daily gain for kids between 2 and 20 months of age was highest in June and July averaging 102 grams. The average dropped to 46 grams per day for the periods August through December and April through May. Gains were lowest, 19 grams per day, in February and March, which corresponds to the middle of the dry season. These rates of gain are equal to rates of gain on very high, high and very low levels of feeding in Indian experiments.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1980.
|Date Available in IDEALS:||2014-12-13|