Response of growing pigs to different levels of ileal standardised digestible lysine using diets balanced in threonine, methionine and tryptophan
2003
Warnants, N. | Oeckel, M.J Van | Paepe, M De
The aim of the trial was to determine the response from 10–15 weeks of Piétrain×Seghers Hybrid barrows and gilts to increased levels of lysine in cereals and soybean meal-based diets balanced in threonine, methionine and tryptophan. Six experimental diets differed in their lysine content from 0.69 to 1.07% standardised ileal digestible lysine. All diets were supplemented with l-threonine, dl-methionine and l-tryptophan in order to satisfy the ideal protein concept. Dietary lysine:crude protein was 0.07 and net energy content was 9.41 MJ/kg feed (based on CVB Veevoedertabel, 2000; Centraal Veevoederbureau, Lelystad, The Netherlands). Pigs were housed in groups of five, per treatment and per sex, corresponding to a total of 45 pigs per treatment that entered the trial at an average weight of 30.5 kg and finished at 48.6 kg. The dietary standardised ileal amino acid content of the feeds was determined in a digestibility trial with four 14-week-old gilts, using a protein-free feed to estimate the basal endogenous N-losses. Feed intake and ADG increased with lysine levels in barrows and gilts, but results suggest that the maximum response was above the highest lysine level tested (1.07% in feed). A requirement for barrows of 1.09% standardised ileal digestible lysine was estimated based on the ADG data, whereas for gilts the ADG data indicated a requirement far beyond 1.07% standardised ileal digestible lysine. The FCR data led to an estimated requirement of 1.06 and 1.14% standardised ileal digestible lysine for, respectively, barrows and gilts. The limited feed intake capacity of the Piétrain×Seghers Hybrid pigs with high lean gain necessitates a feed concentrated in essential amino acids to meet the daily requirement.
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