Effects of dietary level of dried citrus pulp on growth, feed efficiency, carcass merit, and lean quality of finishing pigs
As feed costs continue to be the largest expense for producers, fibrous feedstuffs such as dried citrus pulp (DCP), previously thought to be of marginal quality, are now being explored for use in swine diets because of their availability and low cost. Previous research has focused on DCP as an energy supplement in cattle diets in Florida, but there have been limited studies investigating the effects of differing dietary levels of DCP on the growth, efficiency, carcass merit, and lean quality of finishing pigs. Pigs (n=40) were fed one of four diets for 49 d: a corn soybean meal control diet (CON; n=10), or the same diet with DCP replacing 15% (15DCP; n=10), 22.5% (22.5DCP; n=10), or 30% (30DCP; n=10) of the total diet DM. Overall, Gain:Feed over 49 d was greater in CON and 22.5DCP than 30DCP (P<0.02).Pigs were slaughtered at the University of Florida Meat Laboratory abattoir. Initial pH was taken 60 minutes post exsanguination from the longissimus muscle (LM) and the semimembranosus (SM). Carcasses were fabricated at 24h postmortem where initial meat quality measurements were made at the 10th and 11th rib interface of the LM and the gluteus medius (GM) of the ham face. Fat measurements taken at the blade region of the LM received higher L* values (P<0.04) in CON animals compared to 22.5DCP and 30DCP. When evaluated objectively, bellies from CON pigs were firmer (P<0.0001) than all other treatment groups, but both CON and 15DCP garnered higher subjective firmness scores than 22.5DCP and 30DCP (P≤0.04). Belly thickness at both the blade and flank ends decreased as DCP percentage increased, with CON exhibiting the thickest (P<0.03) and 30DCP having the thinnest (P≤0.02) measurements. LM chops from 30DCP pigs received higher juiciness scores from panelists than 22.5DCP and CON (P≤0.03), while 15DCP chops only earned higher values than CON chops (P=0.03). There was no effect of dietary DCP inclusion on muscle pH, lightness, redness, and yellowness values, chroma, or hue angle, drip or purge loss, live or hot carcass weight, dressing percentage, back fat, loin eye area, percent lean, shear force, cook loss, retail evaluation, or retail lightness, redness, or yellowness values. Though sensory panelists reported increased palatability (juiciness) of chops from pigs receiving 30% DCP, increasing DCP percentage of the total diet DM appeared to be economically detrimental to overall production because of negative impacts on growth performance and pork belly quality.