Establishment and early growth characteristics of six Paulownia genotypes for goat browse in Raleigh, NC, USA

Meat goat production in the eastern USA is increasing as a result of growin g demand from various ethnic groups. Because goats naturally prefer a high proportion of browse in their diets, research was initiated to investigate various silvopastoral production systems. The genus Paulownia contains seve ral species which exhibit rapid juvenile growth and other characteristics t hat justify research into their potential use in meat goat feeding systems. In May 1997, six Paulownia genotypes were planted in a randomized complete block experiment with six replications. Trees were between 6 and 12 cm in height at planting. Genotypes included: P. fortunei seedlings, P. tomentosa seedlings, P. elongata seedlings and three P. elongata clones. Each 4-m wi de plot contained a single row of 12 trees with an intra-row spacing of 1 m . Plant measurements included height, root collar diameter (RCD) at 3 cm ab ove soil surface, and the number of main branches. Leaf samples were collec ted from all six replications for estimates of herbage quality. During 1998 , trees were browsed with goats on two occasions to assess palatability of the herbage and to determine any preference for specific genotypes by the a nimals. Compared with seedling trees of all three species, the three P. elo ngata clones were taller (clones: 79.7 cm, seedlings: 55.9 cm; P < 0.01), h ad larger RCDs (clones: 18.4 mm, seedlings: 13.9 mm; P < 0.01) and had a hi gher branching frequency (clones: 4.9, seedlings: 1.5; P < 0.01) by the end of the first growing season. Mortality averaged 4.8% across all treatments and ranged between 0 and 8%. Early in the 1998 growing season before trees were browsed, P. elongata clones grew more rapidly than seedlings (clones: 116.4 cm, seedlings: 84.1 cm; P < 0.01). Estimates of herbage quality indi cated favorable concentrations of energy and protein for lamina. In vitro t rue dry matter disappearance ranged from 85.4 (blades) to 71.5% (petioles) and crude protein from 25.1 (blades) to 4.9% (petioles). Animals readily br owsed the lamina during two separate sessions, but no clear preference tren ds were observed among the different Paulownia genotypes.