Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/2004
Publication Date: 11/1/2004
Citation: Yen, J., Wells, J., Miller, D.N. 2004. Dried skim milk as a replacement for soybean meal in growing-finishing diets: Effects on growth performance, apparent total-tract nitrogen digestibility, urinary and fecal nitrogen excretion, and carcass traits in pigs. Journal of Animal Science. 82:3338-3345. Interpretive Summary: The present study demonstrates clearly that growing-finishing pigs fed diets containing 5% or 10% dried skim milk had growth performance, carcass characteristics, fresh pork quality, N utilization, the excretion of urinary urea and manure N, the emission of volatile odor compounds, and the shedding of E. coli O157:H7 similar to those fed typical, fortified corn-soybean meal diets. Generally, dried skim milk is too expensive to be used in diets for growing-finishing pigs. Yet, there are times that dietary inclusion of dried skim milk in growing-finishing diets is economically feasible. For example, if USDA can release at low price the surplus dried skim milk purchased by its Commodity Credit Corporation to assist growing-finishing pig producers suffering economic hardship created by recent drought, then, the government-released dried skim milk will be cost-effective for replacing a portion of soybean meal in growing-finishing diets for pigs.
Technical Abstract: Two trials were conducted to determine the replacement nutritive value of dried skim milk for growing-finishing pigs. In a 3-phase feeding trial, 180 growing composite barrows (40.8 ± 2.9 kg BW) were allotted to three dietary treatments. Each phase lasted 28 d. Treatment 1 was the basal corn-soybean meal diets supplemented with crystalline AA to contain true ileal digestible concentrations of 0.83, 0.66, and 0.52% Lys; 0.53%, 0.45%, and 0.40% Thr; 0.51%, 0.45%, and 0.42% SAA (Met + Cys) in phases 1, 2, and 3, respectively. Treatments 2 and 3 were the basal diets with 5 and 10% dried skim milk added. The three diets at each phase were formulated to consist of same quantities of DE, true ileal digestible Lys, Thr, Trp, SAA, Ca, and available P. Pigs were housed 10 per pen (6 pens/treatment), allowed ad libitum access to feed, and slaughtered at 121.6 ± 9.3 kg BW. No differences were detected between pigs fed the basal diet and the dried skim milk diets or between pigs fed the 5% and the 10% dried skim milk diets, respectively, in 84-d ADG (P = 0.84 or P = 0.71), ADFI (P = 0.54 or P = 0.91), and gain/feed (P = 0.80 or P = 0.97) in hot carcass weight (P = 0.66 or P = 0.74), 45-min postmortem longissimus muscle pH (P = 0.90 or P = 0.53), the 10th rib backfat thickness (P = 0.24 or P = 0.77), and longissimus muscle area (P = 0.13 or P = 0.63), and weights of belly (P = 0.43 or P = 0.70), trimmed wholesale cuts (P = 0.43 to 0.80 or P = 0.06 to 0.53), and ham components (P = 0.25 to 0.98 or P = 0.32 to 0.63). In the N balance trial, four littermate pairs of finishing gilts (82.9 ± 2.0 kg BW) were assigned within pair to the basal or the 10% dried skim milk finishing diet. Daily feed allowance was 2.6 × maintenance DE requirement and given in two equal meals. Total fecal collection from eight meals and a 96-h urine collection began on d 14 when gilts weighed 92.1 ± 2.2 kg BW. No differences were found between dietary treatments in gilt's daily N intake (P = 0.33), and the daily output of urinary urea (P = 0.88), urinary N (P = 0.97), fecal N (P = 0.69), and total manure (P = 0.64), as well as apparent total tract N digestibility (P = 0.84), and N retention (P = 0.84). It is concluded that growing-finishing pigs fed diets containing 10% dried skim milk would have growth performance, carcass traits, and N digestibility and utilization similar to those fed typical corn-soybean meal diets.