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Optimal Threonine:Lysine Ratio for Growing Pigs of Different Sexes

  • Chang, W.H. (Department of Animal Science and Technology, College of Agriculture and Life Sciences Seoul National University) ;
  • Lee, J.H. (Department of Animal Science and Technology, College of Agriculture and Life Sciences Seoul National University) ;
  • Heo, K.N. (Department of Animal Science and Technology, College of Agriculture and Life Sciences Seoul National University) ;
  • Paik, I.K. (Department of Animal Science, Chung-Ang University) ;
  • Han, In K. (Department of Animal Science and Technology, College of Agriculture and Life Sciences Seoul National University)
  • Received : 2000.01.27
  • Accepted : 2000.04.11
  • Published : 2000.12.01

Abstract

This study was conducted to investigate the effects of threonine:lysine ratios on growth performance, apparent nutrient digestibility and blood urea nitrogen (BUN) concentration, and to estimate the optimal threonine:lysine ratios for growing barrows and gilts. A total of 150 pigs (Landrace${\times}$Yorkshire${\times}$Duroc, $16.75{\pm}0.42kg$ average body weight, 75 barrows and 75 gilts) was randomly allotted into six treatments in a $2{\times}3$ factorial design. Six diets were formulated to contain 1.12% lysine for barrows and 1.33% lysine for gilts with three threonine:lysine ratios (50, 60 and 70%) for both barrows and gilts. Throughout the whole experimental period (16 to 56 kg body weight), there was no interaction between sex and dietary threonine:lysine ratio in average daily gain (ADG), average daily feed intake (ADFI) and feed conversion rate (FCR). Between sexes, there was a clear sex-effect showing better growth performance of barrows. Barrows consumed more feed (p<0.01) and grew faster (p<0.01) than gilts. For barrows, there was a trend to improved ADG and FCR with increasing threonine:lysine ratio. For gilts, there was a trend to improved ADG and FCR up to threonine:lysine ratio of 60%, but not significant. There was no interaction between sex and threonine:lysine ratio in nutrient digestibilities of growing pigs except for crude ash (CA). Between sexes, there were differences in nutrient digestibilities, except for calcium for which gilts showed higher a digestibility (p<0.01). Among dietary threonine:lysine ratios, there were no differences in nutrient digestibilities. Mean values of essential amino acids (EAA), non-essential amino acids (NEAA) and total amino acids (TAA) digestibilities were not affected by sex and dietary threonine:lysine ratio. There was no evidence of an interaction between sexes and dietary threonine:lysine ratio. Between sexes, total BUN concentration was lower in gilts than barrows (p<0.05). It was concluded that a 70 and 60% dietary threonine:lysine ratio for barrows (1.12% lysine) and gilts (1.33% lysine) tended to result in better growth performances and nutrient utilization and lower BUN concentration than other threonine:lysine ratios.

Keywords

Sexes;BUN;Growing Pig;Growth Performance;Amino Acid Digestibility;Threonine:Lysine Ratio

Acknowledgement

Supported by : MAF-SGRP(Ministry of Agriculture and Forestry-Special Grants Research Program)

Cited by

  1. Effects of dietary fiber on the ideal standardized ileal digestible threonine:lysine ratio for twenty-five to fifty kilogram growing gilts1 vol.94, pp.10, 2016, https://doi.org/10.2527/jas.2016-0680