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Keywords

Finishing pig, growth rate, late finishing, lysine, slow-down program

Abstract

A total of 356 finishing pigs (DNA; 241 × 600; initially 196.3 ± 2.43 lb) were used in a 44-d growth trial to evaluate nutritional strategies to reduce growth rate of pigs beyond 200 lb body weight. A total of 3 diets were manufactured (control, Lys-deficient, and corn) and arranged into 4 nutritional strategies. In stage 1 (d 0 to 28), pens received one of two dietary treatments (control or Lys-deficient). Then on d 28, pens of pigs previously fed the control diet were separated into 2 groups, one fed the control diet and the other the corn diet. Pens of pigs previously fed the Lys-deficient diet were separated into 2 groups, one fed the Lys-deficient diet and the other the corn diet. The control diet contained 13.0% CP and 0.70% standardized ileal digestible (SID) Lys; the Lys-deficient diet contained 10.3% CP and 0.50% SID Lys; and the corn diet contained 8.1% CP and 0.18% SID Lys. There were 9 to 10 pigs per pen and 9 pens per treatment. Pens were assigned to 1 of the 4 nutritional strategies in a randomized complete block design with initial weight as a blocking factor. In stage one (d 0 to 28), pigs fed the Lys-deficient diet had decreased (P < 0.001) ADG, F/G, and d 28 BW compared to pigs fed the control diet. There was no evidence of difference in ADFI between control and Lys-deficient diet. In stage 2 (d 28 to 44), pigs fed the corn diet had decreased (P < 0.05) ADG and poorer (P < 0.05) F/G compared to pigs fed the control or Lys-deficient diets. Pigs fed the Lys-deficient diet in both stages had decreased (P < 0.05) ADG and poorer (P < 0.05) F/G compared to pigs fed the control diet in both stages. For the overall period (d 0 to 44), pigs fed the Lys-deficient diet (stage 1) then corn diet (stage 2) had decreased (P < 0.05) ADG and final BW, and poorer (P < 0.05) F/G compared to the three other treatments. There was no evidence of difference for ADG, F/G, and final BW between pigs fed the Lys-deficient diet in both stages and pigs fed the control diet (stage 1) then corn diet (stage 2). Pigs of these two treatments had decreased (P < 0.05) ADG, F/G, and final BW, compared to pigs fed the control diet in both stages. For carcass characteristics, there was no evidence of difference in carcass yield between treatments. Pigs fed the Lys-deficient diet (stage 1) then corn diet (stage 2) had decreased (P < 0.05) HCW, percentage lean, and loin depth, and increased (P < 0.05) backfat compared to pigs fed the control diet in both stages. There was no evidence of difference in backfat, loin depth and percentage lean between pigs fed the Lys-deficient and corn diet in stage 2. In summary, low dietary Lys levels reduced the growth rate of pigs beyond 200 lb, which resulted in up to 26 lb difference in final BW. These results allow producers to have flexible strategies to slow growth rate and try to maintain ideal marketing weights to cope with the reduced capacity of processing plants.

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

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