TRIBASIC COPPER CHLORIDE AND COPPER-SULFATE AS COPPER SOURCES FOR WEANLING PIGS

We conducted three 28-d experiments involving a total of 915 pigs to a ssess the relative efficacy of tribasic Cu chloride (Cu-2[OH](3)Cl) an d Cu sulfate-pentahydrate (CuSO4 . 5H(2)O) in diets for weanling pigs. Experiments 1 and 2 were conducted at an experiment station (Universi ty of Kentucky), and Exp. 3 was conducted at a commercial feed company 's swine research facilities (United Feeds, Inc.). The basal diet was a fortified corn-soybean meal-dried whey diet (1.25% lysine) with no a ntimicrobials in Exp. 1 or with carbadox (55 mg/kg) in Exp. 2 and 3. I n Exp. 1, 135 pigs were weaned at 27 to 31 d and fed the basal diet wi thout or with 100 or 200 ppm Cu from Cu chloride, or 100 or 200 ppm Cu from Cu sulfate from 7.9 to 17.7 kg BW. The 200 ppm level of Cu from Cu sulfate improved ADG (P <.10), and both levels of Cu from Cu chlori de tended to improve feed:gain. In Exp. 2, 150 pigs were weaned at 27 to 31 d and fed the basal diet without or with 100, 150, or 200 ppm Cu from Cu chloride, or 200 ppm Cu from Cu sulfate from 8.9 to 20.8 kg B W. Addition of 200 ppm Cu improved. ADG (P <.08) and ADFI (P <.01), bu t not feed:gain. Source of Cu did not affect performance. In Exp. 3, 6 30 pigs were weaned at 16 to 20 d and fed a common diet for 10 to 12 d until the start of the experimental period. The same experimental die ts as used in Exp. 2 were fed from 9.1 to 25.5 kg BW. Both Cu sources improved ADG (P <.01), and sources and levels of Cu did not differ. Li ver Cu increased in pigs fed 200 ppm Cu, and Cu sulfate tended to incr ease liver Cu more than did Cu chloride in one experiment, but not in another experiment. The results indicate that tribasic Cu chloride is as effective as Cu sulfate in improving growth in weanling pigs.