| Autor: |
Dalke, B. S., Roeder, R. A., Kasser, T. R., Veenhuizen, J. J., Hunt, C. W., Hinman, D. D., Schelling, G. T. |
| Zdroj: |
Journal of Animal Science; July 1992, Vol. 70 Issue: 7 p2130-2137, 8p |
| Abstrakt: |
One hundred twenty crossbred beef steers averaging 377 kg were used in a 2 × 4 factorial experiment to determine the dose-response effects of recombinant bovine somatotropin (rbST) implants on growth performance and carcass characteristics. The implant dosages were 0 (sham), 40, 80, or 160 mg/wk administered s.c. in the tailhead region on a weekly basis throughout the experiment. The steers were fed a high-concentrate diet, which contained either a degrad-able (DP; soybean meal) or an escape (EP; corn gluten and blood meal) protein source. No dietary protein effect or dietary protein × rbST level interactions were detected. Recombinant bST decreased both DMI (P< .10) and feed/gain (P< .05) in a linear dose-dependent manner. Dosage of rbST did not significantly affect (P> .10) ADG or final weight of the steers. Recombinant bST decreased backfat depth (P< .10), marbling score (P< .05), and quality grade (P< .10) and increased yield grade (P< .10) in a linear dose-dependent manner. Soft tissue composition of the 9-10-11th rib section was altered (P< .01) by rbST administration in a linear dose-dependent manner. The percentage of protein in the rib section was increased by 9.4% and fat was decreased by 11.8% at the 160 mg/wk rbST level compared with the sham-implanted steers. Recombinant bST did not affect (P> .10) dressing percentage, hot carcass weight, kidney, pelvic, and heart fat, or longissimus muscle area.(ABSTRACT TRUNCATED AT 250 WORDS) |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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