The effects of ractopamine hydrochloride (RAC) in a three-phase marketing strategy were reported by G.D. Gerlemann of the University of Missouri and co-authors with the University of Illinois and Elanco Animal Health in a paper in the current issue of Journal of Animal Science.

A total of 1,740 pigs were used in 80 single-sex pens in two blocks. Each pen housed approximately 22 pigs.

Sixteen per cent of the total population of pigs was sold during the first marketing period, 18 per cent was sold during the second marketing period, and the remaining 66 per cent was sold during the third marketing period.

Data were analysed as a randomised complete block design of two treatments.

Pigs in the second marketing group had greater growth performance indicators than pigs in the first marketing group.

Over the entire feeding period, pigs fed RAC were 2.73kg heavier (P<0.0001), had 0.11kg greater average daily gain (P<0.0001) and had a gain:feed ratio 0.04 greater (P<0.0001) than pigs not fed RAC.

Hot carcass weights were 3.3 per cent greater (P<0.0001), carcass yields were 0.68 percentage units) greater (P<0.0001), fat depth was 7.2 per cent less (P<0.0001), loin depth was 5.6 per cent greater (P<0.0001), and estimated carcass lean was 0.97 per cent units greater (P<0.0001) in RAC-fed pigs than those not fed RAC.

By the end of the first marketing period, carcasses from pigs fed RAC (89.73kg) were 2.1 per cent heavier (P=0.04) and gained 0.19kg per day more (P=0.03) carcass weight than those of pigs not fed RAC (87.89kg).

By the end of the second marketing period, carcasses from pigs fed RAC (99.00kg) were 3.1 per cent heavier (P<0.001) and gained 0.14kg per day more (P<0.001) carcass weight than those from pigs not fed RAC (96.02kg).

By the end of the third marketing period, carcasses from pigs fed RAC (102.75kg) were 3.7 per cent heavier (P<0.0001) and gained 0.10kg per day more (P<0.0001) carcass weight than those of pigs not fed RAC (99.06kg).

Although carcass gain per day decreased with extended RAC feeding duration, advantages in hot carcass weight continued to increase as feeding duration was increased from seven to 35 days.

Growth benefits were evident during the initial marketing period but as duration increased, differences diminished.

Gerlemann and co-authors concluded that RAC can provide the expected growth performance benefits when included in the diet for up to 21 days but advantages in hot carcass weight continue to increase throughout the entire 35-day feeding period.

Even though carcass benefits were not as evident in pigs sold during the first marketing period, advantages (particularly in hot carcass weight) continued to increase with each marketing period, the researchers added.

Reference

Gerlemann G.D., G.L. Allee, P.J. Rincker, M.J. Ritter, D.D. Boler and S.N. Carr. 2014. Impact of ractopamine hydrochloride on growth, efficiency, and carcass traits of finishing pigs in a three-phase marketing strategy. J. Anim. Sci. 92:1200-1207. doi: 10.2527/jas.2013-6548

March 2014