Assessment of growth, performance, and end-product value when high oleic soybean oil is fed to market hogs, broiler chickens and laying hens
Authors:   , Schnurbusch Teagan 
Published: August 2021

For the past decade consumers have become more aware of the food they are eating and demand healthier animal products. The use of dietary oils has allowed the livestock industry to manipulate the fatty acid profiles of various animal products, allowing these products to provide consumers with healthier fats. Recent efforts have been placed on increasing monounsaturated fatty acids in human diets. Thus, research has been conducted by manipulating dietary oils to include higher levels of monounsaturated fats in the diet, in turn monogastric tissues alter their fatty acid profiles, providing a healthier product. Little to no research has been done thus far that includes the use of high oleic soybean oil and the effects it can have in the monogastric diet. Therefore, the objective of this project was to evaluate the effects of high oleic soybean oil on growth, performance, and end-product value of market hogs, broiler chickens and laying hens. Barrows (n [equals] 40) were individually housed in pens, stratified by body weight and randomly assigned to one of five treatments: 0 [percent], 2 [percent], 4 [percent], 6 [percent], and 8 [percent] of added high oleic (HO) soybean oil. Pigs were fed ad libitum for 38 d prior to harvest (94.3 kg [plus-minus] 15.38). Feed refusal and individual pig weights were collected every 7 d and used to calculate average daily gain (ADG), gain-to-feed (G:F), and average daily feed intake (ADFi). Following harvest, carcass quality was determined by loin objective color (L*, a* and b*), fat composition and marbling percentages. Fat samples were removed from multiple fat depots (jowl, loin subcutaneous layer 1 and 2, and belly) and analyzed for fatty acid composition. Sample chops were removed between the 10th and 11th rib of the left side of each carcass and analyzed for fatty acid composition, moisture and fat content. Growth performance, carcass characteristics, and fatty acid composition were analyzed using GLM procedure of SAS. Significance was determined at P-value [less than] 0.05. No differences were detected for ADG across treatments (P [equals] 0.3431). Barrows fed 0 [percent] added oil had a higher ADFi compared to barrows fed 4 [percent] added oil (P [equals] 0.0251). Inclusion of dietary oil at 4, 6, and 8 [percent] increased feed efficiency compared to 0 and 2 [percent] (P [equals] 0.033). Dietary treatments did not impact carcass characteristics or carcass quality (P [greater than] 0.05). Dietary treatments did not impact total polyunsaturated fatty acids (PUFA) (P [greater than] 0.05). Increasing levels of HO oil lead to a linear decrease in total saturated fatty acids (SFA) (P [less than] 0.05). There was a linear increase across dietary treatments for total monounsaturated fatty acids (MUFA) and iodine value (IV) for the five fat depots. For subcutaneous layer 1 and 2, the ratio of PUFA to SFA increased across dietary treatments; however, the ratio was not impacted in the jowl fat depot (P [greater than] 0.05). Male Ross 308 broiler chicks (n [equals] 300) were sorted by weight and randomly assigned to one of five treatments containing five replicate pens with 12 broilers each. Treatment groups consisted of corn-soy mash diets that included 0 [percent], 2 [percent], 4 [percent], 6 [percent], and 8 [percent] of added HO soybean oil. Broilers received, ad libitum, a two-phase diet consisting of a starter (d0-21) and a grower (d21-41) phase. Body weight (BW) and feed intake (FI) were recorded weekly and used to calculate feed to gain ratio (F:G). Broilers were slaughtered over a three day kill schedule on d41, d42, d43, after which carcasses were weighed and fabricated. Hot carcass weights were recorded to obtain dressing percentage (DP). Samples of abdominal fat pads were taken for fatty acid profile analysis. Thigh and boneless, skinless breast meat were removed, packaged by pen and frozen for further analysis. Approximately three pounds of thigh and boneless, skinless breast meat were ground, seasoned and linked into five, approximately 114-gram, bratwurst links. Bratwursts were placed on Styrofoam trays and overwrapped with polyvinyl chloride (PVC), then placed into retail display cases (4 [degrees] C) and used for collection of thiobarbituric acid reactive substances (TBARS) on day 0, 1, 3, 5, and 7 of storage. Data were analyzed using PROC GLM procedure in SAS, with level of significance set at P [less than or eual to] 0.05. ADFi significantly decreased across treatments as the percent of added HO oil increased (P [equals] 0.0002). F:G ratio significantly decreased as the percent of added HO oil increased (P [equals] 0.0063). Abdominal fat pads significantly increased in weight as the percent of included HO oil increased (P [greater than] 0.0001). Diet changed (P [less than] 0.001) the proportion of SFA, MUFA, and PUFA in abdominal fat pads. Percent of C18:0 was lower in broilers fed 0 [percent] and 2 [percent] compared to 4 [percent], 6 [percent], and 8 [percent] added HO oil (P [less than] 0.0001). Total SFA decreased as the amount of added HO oil increased (P [less than] 0.0001). Percent of C16:1 decreased as the level of HO oil added increased (P [less than] 0.0001). Percent of C18:1n9 increased significantly as the level of HO oil increased (P [less than] 0.0001). Broilers fed 0 [percent] and 2 [percent] added HO oil had higher amounts of C18:1n7 compared to broilers fed 4 [percent], 6 [percent], and 8 [percent] added HO oil (P [equals] 0.0003). Total MUFA increased significantly as the amount of added HO oil increased (P [less than] 0.0001). Percent of C18:2n6 was higher in broilers fed 0 [percent] and 2 [percent] compared to 4 [percent], 6 [percent], and 8 [percent] added HO oil (P [less than] 0.0001). Percent of C18:3n3 increased across treatments as level of added HO oil increased (P [less than] 0.0001). PUFA:SFA ratio increased as the level of added HO oil increased (P [less than] 0.0001). Results of lipid oxidation showed on day 7 of retail display bratwurst from broilers fed the 0 [percent] and 2 [percent] added HO oil had lower values of malonaldehyde formed compared to the higher fat diets 4 [percent], 6 [percent], and 8 [percent] (P [less than] 0.0001). White Leghorn laying hens (n [equals] 192) were randomly sorted into 24 pens and randomly assigned to one of three treatments: 0.6 [percent] added conventional soybean oil (CON), 3 [percent] added high oleic soybean oil (HO), and 3 [percent] conventional soybean oil (SOY). Hens were fed ad libitum access for 32-weeks, force molted and then returned to treatment for laying cycle two. Feed refusal and pen weights were collected monthly and used to calculate average hen body weight (BW) and feed intake (FI). Eggs were collected daily to calculate average lay rate per hen. Eggs were sampled weekly to measure egg weight size. Eggs were sampled monthly, placed into cold storage for 0, 8, or 12 weeks, and then analyzed for color and fatty acid composition. Data were analyzed using PROC GLM procedure of SAS and significance was set at P-value [less than] 0.05. Hens on the HO diet weighed more than hens on the CON and SOY diet (P [equals] 0.0002). No differences were observed between treatments for feed intake (P [equals] 0.6941). Hens consuming the HO diet had a higher average daily lay rate compared to hens on the CON and SOY diets (P [less than] 0.0001). Egg weights were heavier for HO treatment compared to the CON and SOY treatments during the first laying cycle (P [equals] 0.0002). Diet changed the proportion of SFA, MUFA, and PUFA in egg yolk fat (P [ [percent]less than] 0.001). The HO treatment decreased in total SFA, while the CON and SOY treatments resulted in no changes (P [less than] 0.0001). Total MUFA for HO treatment increased, while the SOY treatment decreased in total MUFA, and the CON treatment resulted in no change (P [less than] 0.0001). The HO treatment decreased in total PUFA, SOY treatment had a significant increase, and the CON treatment resulted in no change in total PUFA (P [less than] 0.0001). HO eggs had a significant increase in C18:1n9 (P [less than] 0.0001). SOY eggs had a significant increase in C18:2n6 and C18:3n3 (P [less than] 0.0001). Eggs from hens fed the HO diet resulted in higher b* values (more yellow) and higher a* values (more red) compared to eggs from SOY treatment (P [less than] 0.05). Subjective color measures recorded using the Roche yolk color fan found HO eggs had higher (more intense yellow-orange) Roche color fan scores compared to CON and SOY treatment eggs (P [less than] 0.0001) throughout time in cold storage. Red Sex Link laying hens (n [equals] 192) were randomly sorted into 24 pens and randomly assigned to one of three treatments: 0.6 [percent] added conventional soybean oil (CON), 3 [percent] added high oleic soybean oil (HO), and 3 [percent] conventional soybean oil (SOY). Hens were fed ad libitum access for 34-weeks, force molted and then returned to treatment for laying cycle two. Feed refusal and pen weights were collected monthly and used to calculate average hen body weight (BW) and feed intake (FI). Eggs were collected daily to calculate average lay rate per hen. Eggs were sampled weekly to measure egg weight size. Eggs were sampled monthly, placed into cold storage for 0, 8, or 12 weeks, and then analyzed for color and fatty acid composition. Data were analyzed using PROC GLM procedure of SAS and significance was set at P-value [less than] 0.05. Hens on the SOY diet weighed more than hens on the CON diet ((P [equals] 0.0481). Hens consuming the HO diet consumed a lower amount of feed compared to the CON and SOY treatments (P [equals] 0.0245). Hens consuming the HO diet had a lower average daily lay rate compared to hens on the CON and SOY diets (P [equals] 0.0325). No differences were detected in egg weight size between treatments during the first or second laying cycle (P [equals] 0.1377, P [equals] 0.7826). Diet changed the proportion of SFA, MUFA, and PUFA in egg yolk fat (P [less than] 0.001). The HO treatment decreased in total SFA, while the CON and SOY treatments resulted in no changes (P [less than] 0.0001). Total MUFA for HO treatment increased, while the SOY treatment decreased in total MUFA, and the CON treatment resulted in no change (P [less than] 0.0001). The HO treatment decreased in total PUFA, SOY treatment resulted in a significant increase, and the CON treatment resulted in no change in total PUFA (P [less than] 0.0001). HO eggs had a significant increase in C18:1n9 (P [less than] 0.0001). SOY eggs had a significant increase in C18:2n6 and C18:3n3 (P [less than] 0.0001). Objective egg color measures resulted in an effect of weeks in storage (P [less than or equal to] 0.05), but no treatment effects were observed. Subjective color measures recorded using the Roche Yolk color score fan found SOY eggs were a lighter yellow compared to CON and HO treatment eggs (P [less than] 0.0001) throughout time in cold storage.