Energetics and Weight Changes of Northern Bobwhites Fed 6 Different Foods

Abstract

Northern bobwhites (Colinus virginianus) fed 6 individual foods were able to metabolize a greater portion of the energy in common sorghum, Maximilian sunflower (Helianthus maximilianii), and a prepared mash than in ox-eye heliopsis (Heliopsis helianthoides), common soybean, and smooth sumac (Rhus glabra). Bobwhites gained weight when provided sorghum or the prepared mash but lost weight when fed sunflower, soybean, heliopsis, and sumac. J. WILDL. MANAGE. 50(2):236-238 Bobwhite populations are limited by various environmental factors, primarily food and cover (Rosene 1969). Habitat enhancement programs of most state agencies and private interests concentrate on these 2 habitat parameters in their attempt to increase quail populations. Dietary stress in northern portions of the bobwhite's winter range often results in weight loss and reduced fat reserves (Robel 1972, Robel et al. 1974), both of which reflect constrained metabolizable energy intake. Kendeigh and West (1965) have documented the gross energy content of many important foods of granivores. Robel et al. (1979a) have reported the metabolizable energy content of important foods of bobwhites. Robel et al. (1979b) conducted comparative energetic studies of bobwhites on 6 foods. This paper reports energetic responses and weight changes of bobwhites fed 5 foods (seeds) and a commercially pelletized mash prepared by the Kansas State University Department of Grain Science and Industry. The study was supported by the Kans. Agric. Exp. Stn. and the Natl. Skeet Shooting Assoc. Charities Found., Inc. This paper is Contribution 85-202-J, Div. Biol., Kans. Agric. Exp. Stn., Kansas State Univ., Manhattan. MATERIALS AND METHODS Twenty-five adult male bobwhites were confined individually in 48 x 25 x 13-cm polypropylene cages with 1.3-cm hardward cloth tops and removable floors (Case and Robel 1974). The caged birds were housed in an environmental chamber at 9L-15D photoperiod and 5 C temperature to simulate Kansas winter conditions. A balanced maintenance diet, P-18, and water were provided ad libitum prior to and between feeding trials, which were conducted during late summer 1980. This diet contained 20.5% protein, 2.7% fat, and 3.6% crude fiber; the major ingredients by weight were ground sorghum (46%) and ground corn (15%). Bird were weighed daily to 0.1 g during the last 2 hours of the dark period to ensure minimal weight variation (West 1960). After bird weights stabilized (varied <2% [t] of the : wt over the preceding 15 days), the birds were ranked from light to heavy and then separated into 5 equal-sized blocks, after which 5-bird, weight-stratified experimental groups were formed by randomly selecting 1 bird from each of the weight blocks. Birds were weight stabilized and rerandomized into 5-bird, weightst fi d blocks between feeding trials. Birds that d ed during feeding trials were replaced ith randomly selected weight-stabilized birds from the weight-stratified blocks. Weights of experimental birds ranged from 136 to 155 g and averaged 143 g. These weight-stable birds were provided seeds of sorghum, sunflower, sumac, heliopsis, and soybean and the balanced pelletized ration (P-18) during 2 consecutive 3-day feeding trials. Body weight and food intake were monitored daily during the feeding trials; spilled feed and excreta were collected at the end of each 3-day period. Because data from the 1st of 2 consecutive 3-day feeding trials vary widely (Clement 1970), only data collected during each of the 2nd 3-day feeding periods were analyzed. Methodology followed Case and Robel (1974) d is detailed in Middendorf (1981). Energy content of oven dried feed and excreta was determined in a Parr Series 1200 adiabatic calorimeter using a Parr 1101 oxygen b mb under 30 atmospheres of pressure. Three