title: Diet modifications to improve finishing pig growth performance and pork quality attributes during periods of heat stress.
abstract: A total of 196 barrows (88 kg) were used in a 2 x 2 factorial arrangement of treatments and housed in a facility (seven pigs per pen) where temperatures cycled between 27 and 35 degrees C. Treatments consisted of (as-fed basis) two CP levels (13.6 or 11.3%) and two levels of added fat (1 or 8%). Diets were formulated to the same true digestible lysine:ME ratio (1.68 g of lysine/Mcal of ME). Diets were fed and growth variables were measured until pigs reached 114 kg of BW. Ham and LM (loin) 24-h pH (PH24), and light reflectance (CIE L*, and a*, and b*, and hue angle) were taken after slaughter. Additionally, loins were removed and measured for i.m. fat, moisture, glycolytic potential, and subjected to a 7-d retail display evaluation that measured pH, light reflectance, and subjective color and odor score. The remaining boneless lumbar loin segment was vacuum-sealed for 14 d and subsequently measured for pH, light reflectance, and color. Pigs fed the high-CP, low-fat diet had a lower ADG than all other treatments (P = 0.06). High-fat feeding resulted in improved ADG (CP x Fat; P = 0.06) and G:F (Fat effect; P < 0.01). Higher fat and lower protein levels both increased final BF (P = 0.07). Pigs fed the low-CP diets had lower ham PH24 (P < 0.01). Loin PH24 was higher with high fat feeding (P = 0.10). Additionally, pigs fed high fat diets had lower L* values on the ham face and cut loin 24 h after slaughter (Fat effect; P <or= 0.02). These loin color differences were maintained through the 7-d retail display and 14-d storage period. There were no differences in loin i.m. fat or moisture content; however, high-fat feeding tended to decrease loin glycolytic potential (P = 0.11). These results suggest that in a hot environment, decreased CP content improved finishing pig ADG when dietary fat supplementation was low. High dietary fat inclusion during heat stress improved ADG and G:F, especially when CP level was elevated. High-fat diets fed in a hot environment increased pork color intensity by decreasing the glycolytic potential at slaughter and elevating muscle pH.
authors.affiliation: Department of Animal Sciences, University of Missouri, Columbia 65211, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Spencer
authors.forename: A M
authors.initials: AM
authors.lastname: Gaines
authors.forename: E P
authors.initials: EP
authors.lastname: Berg
authors.forename: G L
authors.initials: GL
authors.lastname: Allee
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging; D000821:Animal Feed / Q000032:analysis*; D000818:Animals; D003296:Cooking; D004041:Dietary Fats / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D005247:Feeding Behavior / Q000502:physiology*; D005947:Glucose / Q000032:analysis; D018882:Heat Stress Disorders / Q000503:physiopathology / Q000662:veterinary*; D006358:Hot Temperature; D006813:Humidity; D006863:Hydrogen-Ion Concentration; D008297:Male; D008460:Meat / Q000592:standards*; D018482:Muscle, Skeletal / Q000737:chemistry; D013552:Swine / Q000502:physiology*; D014463:Ultrasonography; D015430:Weight Gain / Q000502:physiology
chemical_list: D004041:Dietary Fats; D004044:Dietary Proteins; D005947:Glucose