| Abstract | Boer, Kiko, and Spanish male kids from farms in the south-central US were tested for response to artificial infection with Haemonchus contortus larvae (categorized as resistant [R], of moderate resistance [M], and susceptible [S]) and growth performance in a central test at Langston University. There were 16, 13, and 16 Boer (initial age 3.8 mo and 20 kg), 16, 14, and 20 Kiko (3.7 mo and 19 kg), and 14, 17, and 18 Spanish goats (3.9 mo and 19 kg) in yr 1, 2, and 3, respectively. Males were randomly selected in yr 1, whereas offspring of R and M sires were tested in yr 2 and 3. The test entailed 2 wk of adjustment and 8 wk of data collection, with free access to a 15% CP and 50% concentrate diet in automated feeders. During adaptation, anthelmintic treatment resulted in low fecal egg count (FEC; < 600/g), after which 10,000 infective larvae were administered orally. BW and packed cell volume (PCV) were measured weekly, and FEC was determined 4 to 5 times in wk 6-8. Data were analyzed by the GLM procedure with use of covariates and logarithmic transformation of FEC. DM intake was greatest for M in yr 2 (P < 0.01) but similar among resistance groups in yr 3 (P > 0.05). There was a resistance group by breed interaction in ADG (P = 0.03), with values highest for R and(or) M (236, 267, and 212 g for Boer, 140, 174, and 134 g for Kiko, and 167, 131, and 130 g for Spanish of R, M, and S, respectively; SE = 13.2). There were interactions in FEC of breed × and resistance group (P < 0.01; 962, 1492, and 2774 eggs/g for Boer, 1258, 1968, and 3338 for Kiko, and 276, 1149, and 2373 for Spanish of R, M, and S, respectively), breed × year (P < 0.01; 1102, 1436, and 2690 for Boer, 3577, 1664, and 1323 for Kiko, and 1328, 952, and 1518 for Spanish in yr 1, 2, and 3, respectively), and resistance group × year (P < 0.01; 1164, 746, and 585 for R, 1878, 1261, and 1470 for M, 2965, 2045, and 3476 for S in yr 1, 2, and 3, respectively). PCV was greatest (P < 0.01) for R (27.2, 25.3, and 24.7% for R, M, and S, respectively). In conclusion, selection of meat goat sires through a central performance test improved resistance to internal parasitism without negative influence on growth performance, although change varied among breeds and years. |
