Effects of Lower Dietary Lysine and Energy Content on Carcass Characteristics and Meat Quality in Growing-finishing Pigs

Jinxiao Zhang,Xuan Zhou,Jingdong Yin,Fengna Li,Jianjun Ni,Bing Dong

doi:10.5713/ajas.2008.80191

Abstract

Fifty-four PIC barrows were used to evaluate the effects of lower dietary lysine content and energy level on carcass characteristics and meat quality in slaughter pigs. Pigs were allotted to one of three treatments by body weight with six replicate pens in each treatment. The dietary treatments for body weights of 20-50 kg, 50-80 kg and 80-90 kg were as follows, respectively: control diet (digestible energy 14.22 MJ/kg, lysine/DE 0.67 g/MJ, 0.53 g/MJ and 0.42 g/MJ); a low lysine group (digestible energy 14.22 MJ/kg, lysine/DE 0.49, 0.38 and 0.30 g/MJ); and a low lysine-low energy group or low nutrient group (digestible energy 13.11 MJ/kg, lysine/DE 0.49, 0.38 and 0.30 g/MJ). The daily weight gain, daily feed intake and feed efficiency were calculated in the overall growth period (nearly 12 weeks). Meanwhile, carcass characteristics and meat quality were evaluated at 60 and 90 kg body weight respectively. During the overall growth trial, lowering dietary lysine and nutrient level both decreased weight gain (p<0.05) and feed efficiency (p<0.01). At 60 kg body weight, decreasing dietary lysine and nutrient level noticeably decreased dressing percentage (p<0.01) and back fat depth at last rib of PIC pigs (p<0.01), but enhanced marbling scores (p<0.10), intramuscular fat content (p<0.10) and water loss rate (p<0.01) of the longissimus dorsi muscle. At 90 kg body weight, lean percentage (p<0.01) was evidently reduced by both lowering lysine content and nutrient level in the diet. However, the shoulder back fat depth (p<0.05) and marbling scores of the loin eye muscle (p<0.05) were increased; Lowering dietary nutrient level could improve back fat depth of 10th rib (p<0.01) and last rib (p<0.01), intramuscular fat content (p<0.10), redness (p<0.01) and water loss rate of the loin eye muscle (p<0.05), but decrease loin area (p<0.05). Finally, when comparing the 60 kg and 90 kg slaughter weights, it was found that the shoulder back fat depth (p<0.01, p<0.10), 6th-7th rib (p<0.01, p<0.01), 10th-rib (p<0.01, p<0.01) and last rib back fat depth (p<0.01, p<0.01) of the low lysine and low nutrient group were all obviously increased comparing with the control group. Taken together, the results showed that decreasing dietary lysine content and nutrient level increased intramuscular fat content and water loss rate of longissimus dorsi muscle; On the other hand, both lowering dietary lysine and nutrient level markedly compensated to increase back fat deposition in the later finishing period (body weight from 60

Highlights

In recent years, the carcass lean content of pigs has been increased tremendously by intense selection, consumer acceptance for pork have decreased because of poor meat quality (Witte et al, 2000; Edwards et al, 2003; Schwab et al, 2006)
When previous experimental diets were summarized, most studies that tested the effect of dietary lysine content and energy density were mostly higher than NRC recommendation levels and it is rare to find studies that focused on the effects of lower dietary lysine content and energy density on pork quality
Pigs fed the low lysine diet gained insulin levels are low during energy restriction in most weight 10.3% slower than the control group while pigs fed species (Grey et al, 1970; Trenkle, 1972); Besides, Young low lysine-low energy diets gained weight 19.6% slower et al (1973) certified that plasma insulin levels were than the control

Summary

Introduction

The carcass lean content of pigs has been increased tremendously by intense selection, consumer acceptance for pork have decreased because of poor meat quality (Witte et al, 2000; Edwards et al, 2003; Schwab et al, 2006).

Results

Conclusion