Growth and cashmere production by Spanish goats consuming ad libitum dietsdiffering in protein and energy levels

Thirty-six Spanish goat wethers (196 +/- 12.9 days of age and 17.5 +/- 4.60 kg BW at experiment initiation) from a herd previously selected for cashme re growth were used to determine effects and interactions of ad libitum con sumption of diets differing in concentrations of CP (10% and 15%) and ME (2 .00, 2.35 and 2.70 Mcal/kg; DM basis) on growth and cashmere fiber producti on in an 84-day, fall-season experiment. DM intake was greater (P < 0.05) f or diets with 15% vs. 10% CP (736 vs. 655 g/day) but similar among ME conce ntrations (P > 0.10). ADG was greater (P < 0.02) for 15% vs. 10% CP (79 vs. 53 g/ day) and increased linearly (P < 0.10) as dietary ME level increased (58, 62 and 78 g/day for 2.00, 2.35 and 2.70 Mcal/kg ME, respectively). To tal fleece weight at the end of the experiment was similar (P > 0.10) betwe en CP levels but increased linearly (P < 0.03) as ME concentration in the d iet increased (197, 239 and 227 g/day). Guard hair weight was not affected by dietary treatments (P > 0.10); cashmere length was similar among treatme nts (P > 0.10); and cashmere fiber diameter was not altered by dietary ME l evel (P > 0.10) but was greater (P < 0.05) for 15% vs. 10% CP (16.92 vs. 16 .06 mu m). Cashmere weight was influenced by an interaction between CP and ME levels (P < 0.05); cashmere fiber weight with 10% CP was 92, 82 and 95 g , and with 15% CP was 63, 115 and 99 g for 2.00, 2.35 and 2.70 Meal ME/kg d iets, respectively (SE = 10.2). However, the ranking of treatment means for initial cashmere fiber weight was similar to that at the end of the experi ment, although differences at the beginning were non-significant and of les ser magnitude than at the end. In conclusion, further research with influen ces of concentrations of CP and ME in diets consumed ad libitum on cashmere fiber growth of growing US Spanish wether goats is required, and animal nu mbers and allocation to treatments deserve careful consideration in studies of cashmere fiber production. (C) 2000 Elsevier Science B.V. All rights re served.