D. L. Galloway

Interactive effects of dietary fat source and slaughter weight in growing-finishing swine: I. Growth performance and longissimus muscle fatty acid composition.

Crossbred pigs (n=288) were used to test the interactive effects of dietary fat source and slaughter weight on live performance, carcass traits, and fatty acid composition of the LM. Pigs were blocked by initial BW, and, within each of 9 blocks, pens (8 pigs/pen) were randomly assigned to either control corn-soybean meal grower and finisher diets devoid of added fat (Ctrl) or diets formulated with 5% beef tallow (BT), poultry fat (PF), or soybean oil (SBO). Immediately after treatment allotment, as well as at mean block BW of 45.5, 68.1, 90.9, and 113.6 kg, 1 pig was randomly selected from each pen, slaughtered, and allowed to chill for 48 h at 1 degrees C. Backfat was measured on the right sides, and a sample of the LM was removed for fatty acid composition analysis. Regardless of source, inclusion of fat in swine diets did not (P >or= 0.349) affect ADG, ADFI, or G:F. Furthermore, carcasses from pigs fed diets formulated with 5% fat had greater (P=0.013) average backfat depths than those from pigs fed the Ctrl diet. Body weight, carcass weight, and backfat depths increased (P<0.001) as slaughter weight increased from 28.1 to 113.6 kg. The proportion of SFA in the LM increased (P<0.001) with increasing slaughter weight from 28.1 to 68.1 kg, but SFA percentages were similar between 68.1 and 113.6 kg, and pigs fed the Ctrl diet had greater (P=0.032) proportions of SFA than pigs fed the SBO and PF diets. Moreover, the proportion of all MUFA increased (P<0.001) by 9.4 percentage units from 28.1 to 113.6 kg; however, only pigs fed the SBO diet had reduced (P=0.004) MUFA percentages than those fed the Ctrl, BT, and PF diets. Even though the proportion of PUFA in the LM decreased with increasing slaughter weight, pigs fed SBO had greater PUFA percentages, a greater PUFA-to-SFA ratio, and greater iodine values than pigs fed all other dietary treatments when slaughtered at BW of 45.5 kg or greater (fat source x slaughter weight, P < 0.001). Results of this study indicate that fat source had little to no impact on live pig performance, but feeding a polyunsaturated fat source altered the fatty acid profile of the LM within the first 17.4 kg of BW gain; more specifically, including 5% SBO in swine diets could lead to economical ramifications associated with soft pork or fat.

Interactive effects of dietary fat source and slaughter weight in growing-finishing swine: II. Fatty acid composition of subcutaneous fat.

Crossbred pigs (n=288) were used to test the interactive effects of dietary fat source and slaughter weight on the fatty acid composition of subcutaneous fat. Pigs were blocked by initial BW (28.1 kg), and, within blocks, pens (8 pigs/pen) were randomly assigned to either grower and finisher diets devoid of added fat (Ctrl) or diets formulated with 5% beef tallow (BT), poultry fat (PF), or soybean oil (SBO). Immediately after treatment allotment, as well as at mean block BW of 45.5, 68.1, 90.9, and 113.6 kg, 1 pig was randomly selected from each pen, slaughtered, and, within 1 h postmortem, samples of backfat were removed from each carcass between the 4th and 8th thoracic vertebra and separated into the inner, middle, and outer layers for fatty acid composition analysis. During the first 17.4 kg of BW gain, percentages of all SFA increased by more than 4% in subcutaneous fat of pigs fed the Ctrl and BT diets, but decreased by 4.4 and 7.7% in pigs fed the PF and SBO diets, respectively (fat source x slaughter weight, P<0.001). Proportions of all MUFA in subcutaneous fat from BT-fed pigs increased by 6.1% during the first 17.4 kg of BW gain, but MUFA percentages in SBO-fed pigs decreased by 9.1% between 28.1 and 45.5 kg (fat source x slaughter weight, P<0.001). Conversely, percentages of all PUFA from SBO-fed pigs increased by 39.9%, whereas PUFA concentrations in BT-fed pigs decreased by 12.6% as slaughter weight increased from 28.1 to 45.5 kg (fat source x slaughter weight, P<0.001). Resultant iodine values (IV) of subcutaneous fat from SBO-fed pigs increased (P<0.05) from 73.5 to 85.2 within the first 17.4 kg of BW gain, and remained elevated above those of their contemporaries fed the Ctrl, BT, or PF diets at each subsequent slaughter weight (fat source x slaughter weight, P<0.001). The inner backfat layer had the greatest (P<0.05) proportions of all SFA and the least (P<0.05) proportions of all PUFA, whereas the outer layer had the least (P<0.05) percentages of all SFA but the greatest (P<0.05) percentages of all MUFA. Even though the middle and outer subcutaneous fat layers had similar (P>0.05) PUFA percentages, the greatest (P<0.05) and least (P<0.05) IV were in the outer and middle layers, respectively. As expected, the fat source included in swine diets was responsible for the fatty acid compositional changes in subcutaneous fat, yet the results of this study indicate that feeding 5% SBO dramatically increased the polyunsaturation of subcutaneous fat within the first 17.4 kg of BW gain, with backfat IV exceeding 80 thereafter.

Interactive effects of dietary fat source and slaughter weight in growing-finishing swine: III. Carcass and fatty acid compositions

Crossbred pigs (n=288) were used to test the interactive effects of dietary fat source and slaughter weight on dissected carcass composition and fatty acid composition of composite carcass samples. Pigs were blocked by initial BW, and within each of 9 blocks, pens (8 pigs/pen) were randomly assigned to either control corn-soybean meal grower and finisher diets (Ctrl) or diets formulated with 5% beef tallow (BT), poultry fat (PF), or soybean oil (SBO). Immediately after treatment allotment, as well as at mean block BW of 45.5, 68.1, 90.9, and 113.6 kg, 1 pig was randomly selected from each pen and slaughtered, and primal cuts from right carcass sides were dissected into muscle, fat, bone, and skin components. Muscle and fat tissues were then ground, and random composite samples were collected from each carcass for fatty acid composition analysis. Fat source did not alter pork primal cut yields (P >or= 0.294), nor were the percentages of carcass muscle (P=0.213), fat (P=0.502), and bone (P=0.551) affected by dietary fat source. Conversely, percentages of the whole shoulder and ham decreased linearly (P<0.001), and the percentages of loin and belly increased (P<0.001) linearly with increasing slaughter weight. Moreover, linear decreases (P<0.001) in carcass muscle, bone, and skin, as well as a linear increase (P<0.05) in carcass fat, were observed as slaughter weight increased from 28.1 to 113.6 kg. Composite samples from pigs fed the BT or Ctrl diets had greater (P<0.05) proportions of SFA, particularly oleic and stearic acids, than those from pigs fed the PF and SBO diets when slaughtered at 45.5, 68.1, and 90.9 kg (fat source x slaughter weight, P<0.001). Percentages of MUFA (including palmitoleic, oleic, and cis-vaccenic acids) decreased (P<0.05), and percentages of all PUFA, especially linoleic and linolenic acids, and iodine values increased (P<0.05) in samples from SBO-fed pigs as slaughter weight increased from 28.1 to 113.6 kg (fat source x slaughter weight, P<0.001). Dietary fat source did not affect carcass composition; however, including 5% SBO in swine diets increased the polyunsaturation of pork, which could lead to economic ramifications associated with soft pork and pork fat.

Injection of conjugated linoleic acid into beef strip loins

Beef strip loins (IMPS 180; n=15) were sectioned in thirds and sections (n=45) were left untreated (CNT) or injected with either a commercial powder conjugated linoleic acid (CLA) source (Powder) or a commercial oil CLA source (Oil), whose major isomers were 18:2cis-9, trans-11 and 18:2trans-10, cis-12 CLA isomers. Fresh Oil steaks had 3.20 and 3.15, Powder steaks had 4.67 and 4.62, and CNT steaks had 0.19 and 0.02mg/g muscle tissue (wet basis) of the cis-9, trans-11 and trans-10, cis-12 CLA isomers, respectively. TBARS were similar (Oil) and lower (Powder), compared to CNT. Powder steaks had similar instrumental color, and beef and off flavor characteristics as CNT. Artificial marbling was created with Oil steaks having USDA Small(79) and Powder steaks having USDA Modest(86) marbling scores, while CNT steaks had USDA Slight(94) marbling scores. Injection of CLA can be effective in significantly increasing CLA and potentially creating artificial marbling.

The Immune Response and Performance of Calves Supplemented with Zinc from an Organic and an Inorganic Source1

Abstract Two experiments were conducted to determine the effects of supplemental zinc (Zn) from an organic and an inorganic source on growth performance, serum Zn concentrations, and immune response of beef calves. Treatments consisted of: i) control (no supplemental Zn), ii) Zn sulfate, or iii) Zn-amino acid complex. Zinc sources were supplemented to provide 360 mg of Zn/d. Experiment 1 was a 28-d study using 84 steers (240 ± 1.5 kg) fed bermudagrass hay (21 mg Zn/kg DM) with 1.8 kg/d of the appropriate corn-based supplement. In Exp. 2, 75 heifers (176 ± 2.5 kg) were fed bermudagrass hay (38 mg Zn/kg DM) and the supplements for 140 d. In Exp. 1, ADG was greater (P 0.10) among treatments for the entire 28-d study. In Exp. 2, there was no effect (P>0.10) on ADG as a result of Zn supplementation. In Exp. 2, Zn-supplemented heifers had a greater response (P=0.06) tophytohemagglutinin 24 h after an intradermal injection. In Exp. 2, calves supplemented with Zn-amino acid complex had a greater antibody response to a second vaccination for bovine respiratory syncytial virus than did control or Zn sulfate-supplemented calves (treatment by day interaction, P=0.06). There was not a consistent benefit of supplemental Zn on growth of calves, but there was a positive impact of supplemental Zn on some immune response measurements.

Alternating dietary fat sources for growing-finishing pigs fed dried distillers grains with solubles: II. Fresh belly and bacon quality characteristics.

Crossbred pigs (n = 216) were used to test the effects of phase-feeding beef tallow (BT) and yellow grease (YGr) on fresh belly and bacon quality characteristics of growing-finishing swine fed dried distillers grains with solubles (DDGS). Pigs were blocked by initial BW (26.0 ± 5.3 kg) before allotment to pens (6 pigs/pen), and pens (6 pens/block) were assigned randomly to 1 of 6 dietary treatments: 1) corn-soybean meal-based grower and finisher diets formulated with 4.7% YGr fed during all 5 feeding phases (YG15); 2) corn-soybean meal-based diets formulated with 5.0% BT fed during all 5 phases (BT15); 3) diets containing 5.0% BT fed during the first 2 phases and diets with 4.7% YGr fed the last 3 phases (YG345); 4) diets formulated with 5.0% BT fed during first 3 phases and diets containing 4.7% YGr fed during the last 2 phases (YG45); 5) diets containing 4.7% YGr fed during the first 3 phases and diets with 5.0% BT fed during the last 2 feeding phases (BT45); or 6) diets formulated with 4.7% YGr fed during the first 2 phases and diets with 5.0% BT fed during the last 3 phases (BT345). All dietary treatments were formulated with 30% dried distillers grains with solubles (DDGS) during the first 3 phases, 15% DDGS in the fourth phase, and no DDGS during the last phase. Fresh belly quality data were collected on the left-side bellies, whereas bacon from the right-side bellies was prepared under commercial processing conditions. Additionally, USDA-certified No. 1 slices were collected for cooking characteristics and sensory panel evaluations. Bellies from the YG15-fed pigs were softer (P ≤ 0.05) than bellies from BT15-fed pigs; however, instrumentally measured belly firmness was not (P ≥ 0.06) different among treatments. Concentrations of palmitic, stearic, and oleic acids, as well as all SFA and all MUFA, were greater (P < 0.01) in bellies from BT15- than YG15-fed pigs. In contrast, proportions of linoleic acid, all PUFA, and iodine value were greater (P < 0.01) in belly fat from YG15-fed pigs in comparison with BT15-fed pigs. Yield of commercially processed bacon (P ≥ 0.06), mechanical bacon tenderness (P ≥ 0.69), and bacon palatability attributes (P ≥ 0.55) were not affected by the dietary treatments. Thus, results of this study indicated that phase-feeding BT to pigs fed diets formulated with DDGS produced minor improvements in fresh belly firmness due to greater proportions of SFA but had no effect on yields of commercially processed bacon or bacon quality characteristics.

Effects of Conjugated Linoleic Acid, Salt, and Sodium Tripolyphosphate on Physical, Sensory, and Instrumental Color Characteristics of Beef Striploins

USDA Select striploins (IMPS 180; n= 24) were cut into thirds (anterior, medial, and posterior) and assigned to 1 of 8 treatments utilizing a randomized incomplete block design. Treatments included (1) control (C); (2) 1.5% conjugated linoleic acid (conjugated linoleic acid = CLA) (CGA); (3) 0.4% sodium tripolyphosphate (PHO); (4) 0.5% salt (SAL); (5) 0.4% sodium tripolyphosphate, 0.5% salt (SPH); (6) 0.4% sodium tripolyphosphate, 1.5% CLA (PCL); (7) 0.5% salt, 1.5% CLA (SCL); and (8) 0.4% sodium tripolyphosphate, 0.5% salt, 1.5% CLA (SPC). Treatments were injected with solutions to 110% (10% pump) of their original weight. Treatments with CLA had higher (P < 0.05) marbling scores than treatments that did not. Not including SAL, treatments with salt, or phosphate or a combination of the two had higher tenderness values when sampled by panelists. Fresh steaks with inclusion of CLA had greater amounts (P < 0.05) of the CLA isomers than steaks not having CLA. Cooked steaks having CLA also had greater amounts (P < 0.05) of CLA, except for SCL, which were not different (P > 0.05) from the non-CLA treatments. Day was a significant source of variability for a*, b*, and saturation index. Treatment x day interactions were significant (P < 0.05) for hue angle and L* values. These data suggest that inclusion of CLA can increase amounts of CLA isomers without major deleterious effects to instrumental, physical, and quality characteristics of beef striploin steaks.

Effects of Diet Fed During Backgrounding in Drylot on Ruminal Function of Cattle During Adaptation to Pasture1

This experiment was conducted to determine the effects of type of diet fed in drylot on the changes in the ruminal environment and in situ forage DM disappearance during adaptation from drylot diet to vegetative pasture. Sixteen ruminally cannulated steers were used in a randomized complete block experiment (BW = 535 ± 3.6 kg in Block 1 and 333 ± 3.2 kg in Block 2). Eight steers were assigned to four treatments in each block: ad libitum bermudagrass hay with either a dry supplement (DS) or a molasses-based supplement (MBS) or limit-fed a high-concentrate diet with either a dryprotein supplement (LFDS) or molassesbased protein supplement (LFMBS). Ken

Apparent Magnesium Absorption and Retention and Serum Mineral Concentrations in Lambs Fed Different Sources of Magnesium1,2

This study was conducted to determine apparent Mg absorption and retention and serum mineral concentrations in lambs fed diets containing different dietary sources of Mg. Rambouillet wether lambs (n = 20; 39 ± 0.6 kg) were weighed, bled via jugular puncture, randomized to dietary treatments, and housed in metabolism crates for a 7-d adaptation period followed by 5 d of total urine and fecal collection. Lambs were offered 908 g/d of a basal cottonseed hull, corn-based diet with no supplemental Mg source (control) or the basal diet with MgO, weathered Mg-mica (WMM), or unweathered Mg-mica (UMM) to provide 0.1% of supplemental dietary Mg. Digestibilities of DM, OM, and NDF, as well as serum concentrations of Mg, Ca, Cu, and Zn, did not differ (P>0.10) among diets. Similarly, apparent N absorption and retention (g/d and intake percentage) did not differ (P>0.10) among diets. Apparent Mg absorption (%) by lambs fed MgO and the control (X¯=33.56%) was 52% higher (P<0.05) than that by lambs fed WMM (22.05%), and apparent Mg absorption (%) by lambs fed WMM was 4.24 × greater (P<0.05) than that by lambs fed UMM (5.20%). Lambs fed UMM had lower K and Fe retention (intake percentage) than lambs fed the other diets. Based on these results, MgO seems to be a more available Mg source than the two other sources evaluated, and UMM seems to have negative impacts on Mg, K, and Fe utilization.

Effects of Diet Fed in Drylot on Subsequent Grazing Performance of Growing Cattle1

Two experiments were conducted to determine the effects of diet and rate of BW gain in drylot before grazing on subsequent grazing performance. In Experiment 1, 154 calves (initial BW ± SE = 181 ± 1.98 kg) were fed bermudagrass (Cynodon dactylon (L.) Pers.) hay or were program-fed for an ADG of 0.23, 0.57, or 0.91 kg/d. In Experiment 2, 96 calves (initial BW ± SE = 211 ± 1.63 kg) were fed bermudagrass hay with either a dry (DS) or a molasses-based supplement (MBS) or were program-fed a diet containing either a dry (PFD) or molasses- based (PFM) supplement (2 × 2 factorial). Regression analysis of grazing performance during Experiment 1 suggested that pasture ADG was reduced by 0.10 kg for every kilogram increase in gain during the feeding period (P<0.01; r2 = 0.13). During the first 41 d of grazing small grains or tall fescue, calves program fed in drylot gained 0.31 kg/d (P<0.01) or tended (P=0.07) to gain 0.26 kg/d, respectively, more than calves fed hay in drylot. In Experiment 2, during the first 14 d of the grazing period, program-fed calves (PFD and PFM) gained 0.74 kg/d more (P<0.01) than calves fed hay-based diets (DS or MBS), and calves on the MBS and PMBS treatments gained 0.23 kg/d more (P=0.01) than calves on the DS and PFD treatments. Program feeding is an economical alternative to feeding calves hay and supplement, and diet fed in drylot can influence performance of calves adapting to high quality pasture.