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2025 Vol.52, Issue 4 Preview Page

Animal

Effects of dietary crude protein levels with lysine supplementation on growth performance, meat quality, nitrogen excretion, and hematological parameters in finishing pigs
Su Hyun An1
,
Hwan-Ku Kang1
,
Jin Young Jeong1
,
Min Ji Kim1
,
Pil-Nam Seong2
,
Dong-Gyun Kim2
,
Seong-Hun Shim1*
1Precision Animal Nutrition Division, National Institute of Animal Science, Wanju 55365, Korea
2Animal Resources Food Tech Division, National Institute of Animal Science, Wanju 55365, Korea
*Corresponding Author
1 December 2025. pp. 663-675
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Abstract

This study aimed to evaluate the effects of reducing dietary crude protein (CP) by 1%-unit and supplementing with three graded levels of lysine (Lys) on growth performance, carcass characteristics, meat quality, nitrogen utilization, and blood parameters in finishing pigs. Four dietary treatments were used, consisting of a control diet containing 14% CP and 0.91% Lys and three different diets containing 13% CP with graded Lys levels of 0.91, 0.98, and 1.06%, respectively. Two experiments were conducted using the same dietary treatments. In the feeding trial, 48 pigs (initial body weight [BW]: 85 ± 5 kg) were assigned to four treatments in a 35-day trial (3 pigs/pen). In the metabolic trial, 12 pigs were allocated to four metabolic cages (3 pigs/treatment) for a 7-days trial. In the feeding trial, reducing dietary CP improved gain-to-feed ratio (p < 0.001), with the best results observed in pigs fed 13% CP diets containing 0.98% and 1.06% Lys. However, dressing rate decreased as dietary Lys concentration increased (p = 0.011). In the metabolic trial, weight gain improved linearly with increasing dietary Lys (p = 0.044). Meanwhile, reducing dietary CP by 1%-unit significantly decreased retained nitrogen (p = 0.038) and absorbed nitrogen (p = 0.005). The blood glucose concentration increased linearly (p = 0.018) as dietary Lys concentration increased, whereas the number of neutrophils showed a quadratic increase in response to dietary Lys levels (p = 0.029). These findings suggest that reducing dietary CP by 1%-unit, when accompanied by appropriate Lys supplementation, can maintain or even improve growth performance and nitrogen utilization in finishing pigs without negatively affecting carcass weight and meat quality.

Keywords
crude protein
growth performance
meat quality
nitrogen excretion
pig
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Information
  • Publisher :Institute of Agricultural Science, Chungnam National University
  • Publisher(Ko) :충남대학교 농업과학연구소
  • Journal Title :Korean Journal of Agricultural Science
  • Journal Title(Ko) :농업과학연구
  • Volume : 52
  • No :4
  • Pages :663-675
  • Received Date : 2025-09-28
  • Revised Date : 2025-11-17
  • Accepted Date : 2025-11-18
  • DOI :https://doi.org/10.7744/kjoas.520421
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