Optimum duration of performance testing for growth rate, feed intake, and feed efficiency in growing Boer bucks

Abstract

Central performance testing of meat goats has increased in popularity recently, but minimum test duration has not been ascertained to assess accurately performance traits. This study was conducted to determine the minimum length of time required for accurate evaluation of growing Boer bucks for ADG, dry matter intake (DMI), DMI/BW0.75, and feed efficiency as assessed by ADG:feed intake and residual feed intake. Data were collected from 425 bucks enrolled in Langston University tests lasting 84 days from 2000 to 2009. Bucks averaged 111±25 days of age and 27±8kg BW at the beginning of the test, consumed a pelletized 50% concentrate diet ad libitum, and were weighed weekly. Daily feed intake was determined with Calan gates (American Calan, Inc., Northwood, NH) or automated MK3 FIRE feeders (Feed Intake Recording Equipment, Osborne Industries Inc., Osborne, KS). Weekly data of five performance traits were analyzed using the MIXED procedure of SAS with a repeated-measures model. Residual variance relative to that at 84 days (%) for the goats fed with Calan gates was 358, 293, 235, 193, 153, 127, 116, and 107% for ADG, 184, 173, 161, 149, 136, 123, 113, and 106% for DMI, 374, 317, 256, 203, 161, 137, 118, and 107% for DMI/BW0.75, 445, 320, 225, 162, 135, 124, 111, and 105% for ADG:feed intake, and 174, 154, 143, 128, 113, 107, 103, and 102% for residual feed intake at 28, 35, 42, 49, 56, 63, 70, and 77d, respectively. Residual variance relative to that at 84 days (%) for the goats fed with FIRE was 286, 221, 192, 174, 154, 134, 125, and 110% for ADG, 111, 113, 111, 112, 111, 107, 106, and 105% for DMI, 176, 155, 144, 130, 120, 110, 110, and 110% for DMI/BW0.75, 373, 258, 216, 171, 134, 119, 114, and 106% for ADG:feed intake, and 114, 101, 103, 95, 94, 92, 98, and 103% for residual feed intake at 28, 35, 42, 49, 56, 63, 70, and 77d, respectively. Under either Calan gates or FIRE feeding conditions, the duration of Boer buck performance tests could be decreased from the standard 84 to 63 days with little loss in accuracy.