SELECTING ANGORA GOATS TO CONSUME MORE JUNIPER

Abstract

This research project was initiated in 2003 to develop a more effective tool for biological management of invading juniper species on rangelands through herbivory by Angora goats.  After we had established that juniper consumption in free-ranging goats has a genetic component (heritability = 13%), male and female goats were bred selectively for above- (high) and below-average (low) juniper consumption that was estimated by fecal near-infrared reflectance spectroscopy. Divergent lines are being produced to facilitate the identification of physiological mechanisms that permit some goats to consume considerably more juniper than others as a regular component of their diet.  Because diet is known to affect growth and fiber production, another objective of the project is to establish the effects of the selection protocol on body weights, fleece weights, and fiber characteristics.  Mature females (age > 1.5 yr) and kids were maintained on rangeland and shorn twice a year.  Extreme high- and low-consuming yearling males (10 of each per year) were evaluated annually in a central performance test.  The selection protocol resulted in average EBV for percentage juniper consumption of 3.9 and -0.4 (P < 0.0001) respectively for the 2006-born high- and low-consuming yearlings.  A physiological difference in bioavailability of monoterpenes between high and low consumers was recently detected.  Fiber data for 2006-born 12-mo-old kid goats indicated no significant differences (P > 0.1) in body weight, mohair production and properties between high and low consumers.  However, the adult data for the extreme males indicated that high consuming males have lower body weights than low consumers (53.8 vs. 57.9 kg, P = 0.01). Differences in body weight and several mohair production and quality traits have also been detected in the mature females but at this early stage of the selection program, no substantial differences have been observed and certainly none that would have an economic impact for producers.  Ultimately, we expect to demonstrate that the high-consuming line controls juniper more effectively than either the low-consuming line or unselected Angora goats.  Subsequently, we plan to release high juniper-consuming genetics to commercial breeders for use in range management.