Effects of the Plane of Nutrition on Physicochemical Characteristics and Sensory Quality Traits of the Muscle in Finishing Pigs

Abstract

This study was performed to examine the feasibility of using the low plane of nutrition (LPN) as a means of improving the meat quality of crossbred finishing pigs with a medium weight gain potential. Twenty-four barrows and 24 gilts weighing approximately 48 kg were placed on LPN [a finisher (2.86 Mcal ME/kg and 0.67% lysine) for 91 d] or on a high plane of nutrition [HPN; a commercial grower for 38 d and a finisher (3.35 Mcal ME/kg and 0.9% lysine) for 46 d]. Five barrows and five gilts per treatment weighing approximately 125 kg were slaughtered after the indicated days on the respective diets, followed by physicochemical analysis and sensory evaluation on their muscles. Overall average daily gain was 12.6% less in the LPN group vs. the HPN group (p<0.05). The redness (a*) of fresh longissimus muscle (LM) from the loin as well as from Boston butt was greater in the LPN group vs. HPN whereas the shear force for fresh LM from these primals and semimembranosus muscle was lower in the former. In sensory evaluation for cooked LM, no treatment effect was detected in any of the quality traits examined, except for a lower color score in the LPN vs. HPN group. Results suggest that meat quality of the finishing pigs can be improved to some extent by using LPN. However, the present pigs, whose backfat thickness was 24 mm at 125 kg, are thought not to be lean enough to be fattened over 120 kg.

Assessment of growth performance and meat quality of finishing pigs raised on the low plane of nutrition

“…Notably, the a* value of the muscle, which is known to increase with increasing muscular myoglobin content with age [ 2 ], did not change in response to the low plane of nutrition although the age of LPN at the time of slaughter was 7 d greater than that of MPN. This was partially different from the results of our previous studies [ 13 , 17 ] in which this color value increased or did not change in response to the low plane of nutrition in the ham and/or loin. Collectively, it seems plausible that a 7-d difference in slaughter age is marginal to influence the a* value.…”

“…The loin, ham, Boston butt, and belly were taken for laboratory analyses from 6 carcasses of as many animals per experimental group which had been selected within the animals weighing approximately 120 kg at the end of the feeding trial. Physicochemical characteristics including the color, pH, drip loss, cooking loss, water holding capacity, Warner-Bratzler shear force, firmness, chewiness, and chemical composition of fresh and/or cooked meat were determined as previously described [ 15 , 17 , 21 ].…”

“…Sensory quality traits of fresh and cooked meat were scored according to a 9-ladder whole number scale by 7 trained panelists as previously described [ 6 , 17 , 21 ]. Each trait was scored in such a way that a greater score indicates a better quality, vice versa, regardless of the positive or negative nature or the trait.…”

“…It is generally known that concentrations of favor-enriching substances in meat increase with age in the pig as well as other farm animal species [ 16 ]. It was under this rationale that we investigated the effects of the low plane of nutrition for finishing pigs on physicochemical and sensory characteristics of their meat with a hypothesis that pork quality would be improved if finishing pigs are raised on a low plane of nutrition to increase their age at a predetermined slaughter weight [ 13 , 14 , 17 ]. In our first study using a high lean-gain line, fresh loin and/or ham from finishing pigs fed a low-energy diet containing 3.00 Mcal DE/kg from 80 kg to 110, 125, or 138 kg of body weight exhibited increased redness and marbling score than those from the animals fed a ‘medium’-energy diet containing 3.20 Mcal DE/kg [ 13 ].…”

“…The effect of the plane of nutrition on sensory attributes of cooked meat was not consistent among the primal cuts in that study. In a second trial using a medium lean-gain line, the redness and scores of some sensory quality traits of fresh loin, Boston butt, and ham from the pigs fed a diet containing 3.06 Mcal DE/kg and 0.67 % lysine throughout the finishing period beginning from 48 kg were greater than those from the animals finished on a high plane of nutrition [ 17 ]. Production efficiency, however, was not examined in that study, nor investigated were the effects of the low plane of nutrition relative to those of a medium plane of nutrition, which is retrospectively thought to be optimal for the line of animals used in that study.…”