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Title:Evaluating fat quality and bacon slicing yields in immunologically castrated barrows
Author(s):Tavarez, Marcos
Director of Research:Dilger, Anna C.
Doctoral Committee Chair(s):Dilger, Anna C.
Doctoral Committee Member(s):Boler, Dustin D.; McKeith, Floyd K.; Ellis, Michael; Schroeder, Aubrey
Department / Program:Animal Sciences
Discipline:Animal Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Fat quality
Immunological castration
Abstract:The objective of this dissertation was to determine the effects of immunological castration (Improvest; Zoetis, Kalamazoo, MI) on lipid deposition, fresh belly quality and bacon slicing yields. Immunological castration allows producers to capitalize on the increased feed efficiency and leanness associated with intact males while controlling boar taint. One disadvantage of leaner pigs, however, is that their adipose tissue has increased amounts of unsaturated fatty acids (UFA). This is a cause for concern to packers and processors because it increased issues with fat quality (increased soft and oily fat), especially that of the belly. Bellies with soft and oily fat produce bacon that is difficult to slice. In general, immunological castrated (IC) barrows were leaner, had thinner bellies with greater concentrations of UFA, greater iodine values (IV), and inferior bacon slicing yields compared to physically castrated (PC) barrows. However, lipid composition may be altered and consequently belly firmness improved in IC barrows with increasing time after second Improvest dose. The underlying cause for this improvement is thought to be increased de novo synthesis of fat as a consequence of increase in feed intake. This de novo synthesis was reflected in the first study by increased lipid content (71.6% at 4 wk to 77.2% at 8 wk after second dose in IC) and reduced IV of belly adipose tissue (64.0 at 4 wk to 60.9 g/100g at 8 wk after second Improvest dose in IC). In PC barrows, lipid content was also increased (81.7% at 4 wk to 84.9% at 8 wk), but IV of the belly adipose tissue unchanged (61.5 at 4 weeks to 61.6 g/100g at 8 wk). Therefore, from this first study it was concluded that, as time after second Improvest dose progressed, IV of the belly was reduced with a concomitant increased in lipid deposition. In the second study, the effects of feeding distillers dried grains with solubles (DDGS) to IC barrows were evaluated. Inclusion of 30% DDGS in swine diets increased concentrations of UFA in pork fat. This effect may be magnified in the leaner IC barrows, but potentially improved with increased time after second dose. At 5 wk after second dose, bellies were thicker (P < 0.01) and tended to have greater belly flop distances (P = 0.07) in PC compared to IC barrows, however IV were not different (P = 0.84). Bacon slicing yields (percentage of green weight) were 6.1 percentage units less (P < 0.01) in IC compared with PC. At 7 wk after second dose, bellies from PC tended to be thicker (P = 0.07), have similar flop distances (P = 0.44) and IV (P = 0.54) when compared with IC. Iodine value was greater (P = 0.03) in 30% DDGS fed barrows compared with control fed barrows. Bacon slicing yields (percentage of green weight) were 4.3 percentage units less (P = 0.05) in IC compared with PC barrows. From this second study, it was concluded that while bacon slicing yield was reduced in IC barrows fed control and 30% DDGS diets compared with PC barrow counterparts, withdrawal of DDGS improved bacon slicing yields of IC barrows. For the third study, both the effects of age at slaughter and time after second Improvest dose were quantified on fresh belly characteristics and commercial bacon production in IC barrows compared with PC barrows and gilts. For pigs slaughtered at 24 wk, administration of the second Improvest dose was staggered so that IC barrows were slaughtered at 4, 6, 8, and 10 wk after second dose. In pigs slaughtered at 26 and 28 wk, IC barrows were slaughtered at 6 and 8 weeks after second dose, respectively. In pigs slaughtered at 24 wk of age, belly thickness, flop distance, and bacon lipid content were increased linearly (P < 0.04) and iodine value (IV) tended to decrease (P = 0.08) with time after second dose in IC barrows. Bacon slicing yields (as percent of green and cooked weight) were curvilinearly increased with time after second dose (P < 0.05), but were similar (P > 0.14) between sex classes. In pigs slaughtered from 24 to 28 wk of age, fatness (last rib and bacon) was increased (P < 0.01) and IV reduced (P < 0.01) in IC barrows with age at slaughter, but not (P > 0.11) in PC barrows and gilt combined. Slicing yields (green and cooked weight) were increased (P < 0.01) with age at slaughter in IC barrows. Both yields were superior (P < 0.01) in IC barrows compared to PC and gilts at 28 wk. Increasing both, age at slaughter and the time after second Improvest dose improved fresh and cured belly characteristics in IC barrows, however age at slaughter seemed to have a greater marginal effect on the belly. Conclusions from these studies indicate that, in general, increasing age at slaughter coupled with time after second Improvest dose allow IC barrows to become heavier and to increase fat deposition, as a result fresh belly quality and bacon slicing yields are improved while becoming more similar to PC barrows.
Issue Date:2014-05-30
Rights Information:Copyright 2014 Marcos Tavarez
Date Available in IDEALS:2014-05-30
Date Deposited:2014-05

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