Effects of Kemtrace Cr Level and Feeding Regimen on Finishing Pig Growth Performance and Carcass Characteristics

A study was conducted to determine the effects of increasing Cr (KemTRACE Chromium propionate, Kemin Industries Inc., Des Moines, IA) and feeding regimen on growth and carcass performance of finishing pigs housed in a commercial environment. A total of 1,206 pigs (PIC 337×1050; initial BW=28.67 kg) with 27 pigs/pen and 9 pens/treatment were used in a 125 d study. Pigs were split by gender upon arrival at the facility, with 4 blocks of each gender and a final mixed gender block. Gender blocks were randomly allotted to groups of 5 pen locations within the barn. Block was included in the generalized linear mixed model (PROC GLIMMIX; SAS Institute Inc., Cary, NC) as a random effect and accounted for gender, initial BW, and barn location. Diets were corn-soybean meal-dried distiller grains with solubles-based and were fed in 5 phases. All nutrient concentrations met or exceed NRC (2012) requirement estimates. Treatments were arranged as a 2×2+1 factorial with two levels of Cr supplementation (100 or 200 µg/kg) fed during two growth phases (grower = 63-139 kg; finisher = 63-139 kg) and a control diet containing no added Cr. There was no effect of changing Cr supplementation during the finishing period. Therefore, only linear and quadratic effects of increasing Cr within period were considered using all treatments, as well as linear and quadratic effects of increasing Cr for the full duration using the 3 treatments which maintained a constant Cr concentration throughout. Increasing Cr during the grower period reduced (quadratic, P<0.001) ADG and G:F. During the finisher period, increasing Cr tended (quadratic, P<0.058) to increase G:F with the best G:F observed in pigs fed 100 µg/kg Cr. Overall, increasing Cr had no impact on ADG or ADFI; however, G:F was maximized (quadratic, P<0.020) when pigs were fed 100 µg/kg of Cr. Carcass characteristics were not influenced (P>0.10) by added Cr or feeding regimen. In summary, increasing Cr supplementation up to 100 µg/kg elicited improvement in G:F with no impact on ADG, ADFI, or carcass characteristics.

Table 1. Effect of added Cr on pig performance, d 0 to 125
Grower added Cr, µg/kg:	0	100	200	100	200		Probability, P<
Finisher added Cr, µg/kg:	0	100	200	200	100	SEM	Linear	Quadratic
ADG, kg	0.89	0.90	0.89	0.90	0.89	0.009	0.796	0.136
ADFI, kg	2.23	2.21	2.21	2.23	2.23	0.037	0.472	0.651
G:F	0.400	0.408	0.402	0.404	0.402	0.004	0.463	0.020