|Yen, Jong Tseng|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/22/2005
Publication Date: 11/1/2005
Citation: Yen, J., Klindt, J.M., Kerr, B.J., Buonomo, F.C. 2005. Lysine requirement of finishing pigs administered porcine somatotropin by sustained-release implant. Journal of Animal Science. 83:2789-2797. Interpretive Summary: A sustained-release implant (pST-SR) has been developed to deliver continuously a daily dose of 2 mg of pST to pigs for 42 d. The present study establishes that administration of 4 mg pST/d via pST-SR implant is effective in improving the efficiency of feed utilization, and increasing carcass leanness and quantity of lean pork in finishing barrows. The present study further confirms that increased dietary lysine concentration and thus daily lysine intake is required to fully exploit the benefits of pST in finishing pigs. With 4 mg pST/d via pST-SR implant, finishing barrows need 0.88% total lysine and 0.75% apparent ileal digestible lysine in the diet. Based on daily feed intake, these concentrations correspond to daily intake of 26.1 g total lysine and 22.4 g apparent ileal digestible lysine. Additionally, the present study also indicates that pST-SR implant decreases daily feed intake and plasma urea N concentration, and thus has a potential in reducing manure N excretion and environmental pollution in swine operations. All these results demonstrate clearly that the benefits of pST for finishing pigs can be realized by pST-sustained release implant rather than laborious daily injection.
Technical Abstract: To alleviate laborious daily injection of porcine somatotropin (pST), a sustained-release implant (pST-SR) has been developed to deliver continuously a daily dose of 2 mg of pST to pigs for 42 d. In the present study, 96 white composite (Large White x Landrace) finishing barrows (83.6 +/- 1.2 kg BW) were assigned to receive 0 or 2 pST-SR implants (4 mg pST/d) and to consume one of six diets differing in total lysine concentration (0.29, 0.52, 0.75, 0.98, 1.21, and 1.44). Diets were formulated to be isocaloric and based on ideal protein concept. Pigs were housed individually, allowed ad libitum access to feed and water, and slaughtered at 112 kg BW. The pST-SR affected neither ADG (P = 0.88), nor 10th rib longissimus muscle area (LMA, P = 0.51), but decreased (P < 0.01) ADFI, average backfat thickness, 10th rib fat depth, leaf fat, and ham fat, improved (P < 0.05) gain/feed (G/F), and increased (P < 0.01) weights of four trimmed lean cuts (T-cuts), and ham lean and bone percentages. Increasing total lysine increased ADG (linear, P < 0.01; quadratic, P < 0.05) and ADFI (linear, P < 0.01). The G/F, plasma urea N (PUN) and T-cuts were affected by pST-SR x dietary lysine interactions (P < 0.01). Without pST-SR, the G/F of was not different (P = 0.37) between pigs fed 0.52% and higher total lysine. With pST-SR, the G/F was lower (P < 0.05) for pigs fed 0.52% than 0.98 and 1.44% total lysine. Without pST-SR, increasing total lysine increased PUN linearly (P < 0.01). With pST-SR, no PUN differences (P = 0.19) occurred between 0.29 and 0.52%, 0.98 and 1.21%, or 1.21 and 1.44% total lysine feedings. The T-cuts of pigs without pST-SR were not different (P = 0.30) among those fed 0.29, 1.21, and 1.44% total lysine. With pST-SR, the T-cuts were lower (P < 0.01) for those fed 0.29% than 1.21 and 1.44% total lysine. Estimates of total lysine requirements of pigs without and with pST-SR, respectively, were 0.52 and 0.86% for growth (ADG and G/F) and 0.173 and 0.88% for lean production (LMA and T-cuts). Equivalent apparent ileal digestible lysine requirements of pigs without and with pST-SR, respectively, were 0.44 and 0.68% for growth, and 0.62 and 0.75% for lean production. A daily intake approximately 26.1 g of total lysine or 22.4 g of apparent ileal digestible lysine is needed to maximize lean production in finishing barrows receiving 4 mg pST/d via sustained-release implant.