Studies on the tryptophan requirement of lactating sows. Part 1: Estimation of the tryptophan requirement by performance

Abstract

Mature sows were evenly assigned to six dietary treatments, which differed only in the concentration of total (apparent ileal digestible, AID) tryptophan (Trp) amounting per kg feed to 1.2 g (0.8 g) to 4.2 g (3.8 g) in diets 1-6. For a total of 72 lactations (28 days) sows' feed intake was measured daily and body weight was measured on day 110 of pregnancy and on days 1 and 28 of lactation. Litter size was standardized to 10-12 piglets within 1 week after farrowing. The piglets were weighed at days 1, 21 and 28. Milk yield was recorded by the weigh-suckle-weigh method on days 20 and 21. Concentrations of milk fat and protein were measured in manually drawn samples (days 20 and 21) by infrared spectroscopy. Average daily feed intake of the sows was 3.4, 4.7, 4.7, 6.1, 5.1 and 4.7 kg (diets 1-6 respectively, p < 0.001). Body weight losses of the sows during lactation were 30.8, 16.9, 19.2, 9.5, 14.1 and 13.1 kg (diets 1-6 respectively, p < 0.05). Milk output in the average of days 20 and 21 was 6840, 8192, 8362, 9035, 8618 and 8140 g/day, respectively (p < 0.01). There were no differences in milk fat or protein contents. Daily weight gain of the piglets in the average of lactation was 157, 184, 184, 187, 185 and 177 g, respectively (p < 0.10). Based on the results of this study the estimated Trp requirement of lactating sows for optimal performance was calculated with 1.9 g AID Trp/kg in the lactation diet (according to 2.0 g true ileal digestible Trp and approximately 2.6 g Trp on total basis).

Reduced feed intake of lactating primiparous sows is associated with increased insulin resistance during the peripartum period and is not modified through supplementation with dietary tryptophan1

“…Sows were fed 2.9 kg/d provided in 2 equal meals at 0900 and 1400 h. Then, sows were allotted to 1 of the 2 lactation diets (differing in their Trp content) according to their BW and backfat depth measured at 1 mo after insemination to have similar body conditions in the 2 groups. Lactation diets were formulated to provide 25% more (Trp+) or 25% less (Trp−) of total Trp:Lys than the value that maximizes the ADFI of multiparous sows in Paulicks et al (2006). The Trp+ diet was obtained through addition of 0.12% l-Trp in the Trp− diet.…”

“…However, it is not known whether the degree of insulin resistance could vary within sows having similar body conditions and be related to ADFI. A deficient as well as an excessive dietary supply of Trp impairs the appetite of lactating sows (Lewis and Speer, 1974;Paulicks et al, 2006). The actual recommendation for the Trp:Lys ratio in the lactation diet is 18% (Dourmad et al, 1991;NRC, 1998) but was recently estimated at 24% on the basis of feed intake and uremia (Pampuch et al, 2006;Paulicks et al, 2006).…”

“…A deficient as well as an excessive dietary supply of Trp impairs the appetite of lactating sows (Lewis and Speer, 1974;Paulicks et al, 2006). The actual recommendation for the Trp:Lys ratio in the lactation diet is 18% (Dourmad et al, 1991;NRC, 1998) but was recently estimated at 24% on the basis of feed intake and uremia (Pampuch et al, 2006;Paulicks et al, 2006). However, these authors studied multiparous sows only, and the effect of such a dietary Trp concentration on the performance of lactating primiparous sows remains to be investigated.…”

Tryptophan metabolism and related B vitamins in the multiparous sow fedad libitumafter farrowing

“…Both diets were provided in pellets and their compositions are presented in Table 1. Tryptophan concentration in the lactation diet was close to the recommendation of Paulicks et al (2006) to prevent any 468 E. Mosnier et al…”

“…Among factors controlling the voluntary feed intake of the lactating sow, some nutrients can be suspected to interfere with appetite when inadequately supplied. For example, Paulicks et al (2006) reported that sows fed a lactation diet supplying 2.4 g/kg of tryptophan (Trp) consumed more feed, had attenuated body weight loss and weaned heavier piglets than sows fed a diet containing 1.9 g/kg of Trp, as recommended by the National Research Council (NRC 1998). However, these authors observed a decreased feed intake and an increased body weight loss in lactating sows when the dietary supply of Trp exceeded 2.4 g/kg, probably because of impairment in Trp homeostasis.…”