title: Effect of dietary lysine level and environmental temperature during the finishing phase on the intramuscular fat content of pork.
abstract: This study was designed to investigate the effects of dietary lysine level on the intramuscular fat content of the longissimus in finishing pigs reared at two environmental temperatures. Seventy-two hybrid gilts were individually penned and given ad libitum access to either a diet formulated to meet their lysine requirement (6.4 g/kg lysine) or a lysine-deficient diet (4.8 g/kg). Pigs were held at one of two environmental temperatures (thermoneutral [18 degrees C] or hot [32 degrees C]). The study was carried out between approximately 90 and 126 kg live weight; pigs in the thermoneutral and hot environments were on test for 5 and 7 wk, respectively. There were no interactions between dietary lysine level and environmental temperature. Dietary lysine content did not influence feed intake or average daily gain; however, pigs on the lysine-deficient diet had a poorer gain:feed ratio than those fed to requirement (P < .01). High environmental temperature decreased feed intake (P < .001) and average daily gain (P < .01) but improved gain:feed ratio (P < .01). Backfat at the 10th rib was increased and loin eye area and estimated percentage lean in the carcass were decreased for pigs on the lysine-deficient diet. The higher environmental temperature resulted in an increase in carcass length but had no effect on other carcass measurements or intramuscular fat. Feeding the lysine-deficient diet resulted in an increase of .55 percentage unit in longissimus intramuscular fat content (P < .01); however, there was no difference in subjective marbling scores between the diets. Warner-Bratzler shear force values were not affected by dietary lysine level or environmental temperature. Results from this study suggest that feeding of lysine-deficient diets at the end of the finishing period can increase intramuscular fat deposition under thermoneutral and hot conditions.
authors.affiliation: Department of Animal Sciences, University of Illinois, Urbana, 61801, USA.
authors.forename: D P
authors.initials: DP
authors.lastname: Witte
authors.forename: M
authors.initials: M
authors.lastname: Ellis
authors.forename: F K
authors.initials: FK
authors.lastname: McKeith
authors.forename: E R
authors.initials: ER
authors.lastname: Wilson
mesh_terms: D000273:Adipose Tissue; D000818:Animals; D004032:Diet; D008239:Lysine / Q000378:metabolism*; D008460:Meat / Q000592:standards*; D009132:Muscles; D011897:Random Allocation; D013552:Swine / Q000378:metabolism*; D013696:Temperature
chemical_list: D008239:Lysine