Effects of Immunological Castration and DDGS on Carcass Cutability and Commercial Bacon Slicing Yields of Barrows

Bacon slicing yield was lower in immunologically castrated male pigs the control diet (without distiller’s dried grains with solubles; DDGS) and 30 per cent DDGS than their counterparts that had been physically castrated, according to a recent study at the University of Illinois. Withdrawal of DDGS improved bacon slicing yields only in the immunologically castrated pigs.
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In a paper in Journal of Animal Science recently, first-named author M.A. Tavárez of the University of Illinois at Urbana-Champaign and others from Ohio State University, Kansas State University, Zoetis and Sugar Creek Packing Co. describe a study in which male pigs were randomly assigned to a castration method at birth and allotted to 48 pens (28 pigs per pen).

Physically castrated (PC) barrows were castrated at two days of age; immunologically castrated (IC) barrows were administered Improvest (GnRF analog diphtheria toxoid conjugate; Zoetis, Kalamazoo, Michigan) at 16 and 20 weeks of age.

DDGS feeding strategies included either 0 DDGS (control), 30 per cent DDGS (30% DDGS) fed from six weeks of age to slaughter or 30 per cent DDGS fed from six weeks of age to second dose of Improvest and then fed 0% DDGS until slaughter (withdrawal).

Four barrows closest to the median pen weight at 4.5 weeks after second dose were selected for evaluation; two were randomly selected and slaughtered at five weeks and the other two at seven weeks after second dose.

Data from each slaughter time were analyzed independently as a 2×3 factorial design with pen as the experimental unit.

At five weeks after second dose, bone-in lean cutting yields were 2.63 per cent units greater (P<0.01) in IC when compared to PC.

Bellies were thicker (P<0.01) and tended to have greater belly flop distances (P=0.07) in PC than IC, however iodine values (IV) were not altered (P=0.84).

Carcass traits (P≥0.10), cutting yields (P≥0.43), and fresh belly characteristics (P≥0.08) were minimally affected by DDGS feeding strategy.

Bacon slicing yields (percentage of green weight) were 6.10 percentage units less (P<0.01) in IC than PC.

At seven weeks after second dose, bone-in lean cutting yields were 1.57 percentage units greater (P=0.03) in IC than PC.

DDGS feeding strategy had no effect (P≥0.83) on boneless carcass cutting yields in IC; while in PC, these yields were 2.32 percentage units less (P<0.02) in control-fed barrows than other feeding strategies (castration method × feeding strategy; P=0.03).

Bellies from PC tended to be thicker (P=0.07) and have similar flop distances (P=0.44) and IV (P=0.54) as IC.

Iodine value was greater (P=0.03) in 30% DDGS-fed barrows than control-fed barrows.

Bacon slicing yields (percentage of green weight) were 4.27 percentage units less (P=0.05) in IC than PC.

These data suggested that while bacon slicing yield was reduced in IC barrows fed control and 30 per cent DDGS than their PC barrow counterparts, withdrawal of DDGS improved bacon slicing yields of IC barrows.


Tavárez M.A., B.M. Bohrer, M.D. Asmus, A.L. Schroeder, R.J. Matulis, D.D. Boler and A.C. Dilger. 2014. Effects of immunological castration and distiller’s dried grains with solubles on carcass cutability and commercial bacon slicing yields of barrows slaughtered at two time points. J. Anim. Sci. 92(7):3149-3160. doi: 10.2527/jas.2013-7522

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August 2014

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