| Popis: |
The objectives were to determine if the augmented growth performance of gilts administered anti-gonadotropin-releasing factor (GnRF) would require additional lysine and if anti-GnRF-treated gilts would require additional lysine to enhance carcass characteristics. The study treatments were arranged as a 2×3 factorial: control vs anti-GnRF (day 7 and 84; day 0 = 11 wk of age) and lysine at 100, 110, or 120% of requirement of the control gilts. Pen (n = 60) was the experimental unit (10 pens per treatment with 18 or 19 pigs per pen). There was no lysine × anti-GnRF interactions (P ≥ 0.2). Immunized gilts grew 3.7% faster and consumed 3.9% more feed with similar gain:feed from day 0 to market with increases occurring after the administration of the 2nd anti-GnRF dose. Immunized gilts weighed 3.4-kg more at marketing. The timing of marketing (4- or 6-week post 2nd dose) influenced the effects of anti-GnRF. Hot carcass weight, loin depth, and belly weight and thickness in anti-GnRF treated gilts were similar to control gilts at 4-weeks post 2nd dose but were greater in anti-GnRF vs. control (P ≤ 0.05) when harvested 6-weeks post 2nd dose. Backfat was greater, and lean was less, in immunized gilts vs. controls regardless of time to harvest. In conclusion, gilts immunized against GnRF had heavier carcass weights and required no additional lysine compared to controls. |
