Effects of bovine somatotropin and ruminally undegraded protein on feed intake, live weight gain, and mohair production by yearling Angora wethers.

Yearling Angora wethers (n = 24; 24+/-1.0 kg BW) were used in an experiment with a 2 x 2 factorial arrangement of treatments to investigate effects of bovine somatotropin (bST) treatment and dietary level of ruminally undegraded protein on DMI, ADG, and mohair production. Untreated casein (UC) or casein treated with formaldehyde (TC) was included at 7% DM of a diet containing 11% CP and 46% concentrate. A slow-release bST form was administered weekly to deliver 0 (Control) or 100 microg/ (kg BW.d) of bST. Plasma concentrations of bST and IGF-I were increased (P < .05) during the 7-d period following bST injection. Ruminal fluid ammonia N concentration was lower (P < .01) for TC than for UC before feeding (6.6 vs 7.5 mg/dL) and 4 h later (8.2 vs 12.2 mg/dL), and total VFA concentration was lower (P < .01) for TC than for UC. Treatment with bST decreased (P = .08) DMI with UC (1.15 vs .91 kg/d) and increased (P = .08) DMI with TC (.95 vs 1.06 kg/d). Formaldehyde treatment of casein increased ADG (65, 74, 55, and 91 g/d; P = .03) and clean fleece production (P < .01; 14.1, 17.3, 15.0, and 18.4 g/d for UC-Control, TC-Control, UC-bST, and TC-bST, respectively), with no effect of bST during the 8-wk period of treatment or for the 8 wk thereafter (P > .10). In conclusion, with yearling Angora wethers, bST does not seem useful to enhance mohair production and may not alter effects of dietary level of ruminally undegradable protein on mohair production.

Validation of antibiotic residue tests for dairy goats.

The SNAP test, LacTek test (B-L and CEF), Charm Bacillus sterothermophilus var. calidolactis disk assay (BsDA), and Charm II Tablet Beta-lactam sequential test were validated using antibiotic-fortified and -incurred goat milk following the protocol for test kit validations of the U.S. Food and Drug Administration Center for Veterinary Medicine. SNAP, Charm BsDA, and Charm II Tablet Sequential tests were sensitive and reliable in detecting antibiotic residues in goat milk. All three assays showed greater than 90% sensitivity and specificity at tolerance and detection levels. However, caution should be taken in interpreting test results at detection levels. Because of the high sensitivity of these three tests, false-violative results could be obtained in goat milk containing antibiotic residues below the tolerance level. Goat milk testing positive by these tests must be confirmed using a more sophisticated methodology, such as high-performance liquid chromatography, before the milk is condemned. LacTek B-L test did not detect several antibiotics, including penicillin G, in goat milk at tolerance levels. However, LacTek CEF was excellent in detecting ceftiofur residue in goat milk.