Feed intake and body weights of suckling sows and piglets in dependence of dietary threonine supplementation. 1. Contribution about the threonine requirement of suckling sows

To determine the requirement. of suckling sows for threonine (Thr) the effects of graded threonine supplementation on feed intake and changes of body weight of sows and piglets were examined using 49 multiparous sows (German Landrace) over a total of 72 lactation periods lasting 35 days each. The sows were equally distributed to six treatments (I-VI). Each group was fed with the same basic diet covering the requirements of energy and nutrients except threonine which was supplemented using L-Thr to concentrations of 0.31 g (I), 0.38 g (II), 0.45 g (III), 0.61 g (IV), 0.75 g (V) and 0.89 g Thr (VI) per 100 g fresh matter. Feed intake of the sows was determined daily, their body weights at day 110 of gravidity and at day 1, 22, and 35 of lactation. The piglets were weighed at day 1, 21, and 35. The intake of piglet feed, which was offered from day 21, was determined at day 35 for each litter. The daily feed intake of the sows as well as their protein and energy intakes were not affected by the Thr concentration of the diet and amounted in the average of all groups to 4300 g fresh matter, 422 g crude protein and 59.0 MJ ME during the whole lactation period. The daily Thr intake differed significantly between the treatment groups I-VI with 13.9/16.3/21.2/27.6/34.2/42.0 g. The mean body weight of the sows was 263 kg at day 110 of gravidity and 255 kg after farrowing and was similiar for all groups. During the whole lactation daily body weight losses were distinctively higher for groups I and II with 1200 g than for groups III-VI with 880 g on the average. The mean body weight of the piglets was 1536 g. Their daily weight gains were 188 g in the average of the first 21 days and 205 g for the next 14 days resulting in a mean body weight of 8350 g at weaning. Nevertheless the piglets of groups I-III with 5360 g body weight were distinctively lighter than those of groups IV-VI with 5600 g. At weaning the piglets of groups I and II weighing 7800 g were significantly inferior to the others with 8700 g body weight. The consumption of piglet feed averaging 17g/piglet and day was not affected by the treatment. With regard to the body weight changes of sows and piglets using regressional equations a concentration of 0.71% Thr in the diet of lactating sows might be necessary. This means a daily intake of about 31 g Thr in the average of the whole lactation.