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A total of 1,034 pigs produced by breeding PIC sows to 2 different PIC terminal sires were used to create 3 distinct weaning weight populations so that postweaning growth to 125 kg could be studied. The rearing strategies resulted in BW that ranged from 4.1 to 11.5 kg by 20 d of age. Sows and corresponding litters were allocated to 3 treatments: sow reared (SR; n = 367) for 20 d, sow reared for 14 d (14W; n = 330), and sow reared for 2 d (2W; n = 337). Sows were removed from 2W and 14W groups, but progeny remained in the crates and received milk replacer ad libitum (for 18 and 6 d, respectively) until the contemporary SR pigs were weaned at 20 d of age. The SR pigs (6.49 [+ or -] 0.15 kg) weighed 1.01 kg less than 14W pigs (7.5 [+ or -] 0.14 kg) and 2.26 kg less than 2W pigs (8.75 [+ or -] 0.14 kg; P < 0.05). The 14W pigs weighed 1.25 kg less than 2W pigs (P < 0.05). Nursery ADG for the 2W group (547 g/d) was 35 g/d less (P < 0.05) than 14W pigs. The 14W pigs (165 d) required 3 fewer (P < 0.05) days to reach 125 kg of BW compared with SR pigs. The SR and 14W pigs gained BW 24 and 20 g/d faster (P < 0.05) in the postnursery period when compared with 2W pigs. The SR and 2W pigs consumed 0.10 and 0.12 kg/d less (P < 0.05) during this period when compared with 14W pigs (2.32 kg/d). Gain:feed of SR was improved (P < 0.05) when compared with the 14W and 2W pigs over 167 d of age (0.44 vs. 0.42 and 0.42, respectively). Lean percentage was 0.7% greater (P < 0.05) in carcasses from SR pigs (55.0%) compared with carcasses from 2W pigs (54.3%) when adjusted to a constant HCW. A study of the effect of weaning weight on days to 125 kg was limited to SR and 14W groups because maternal deprivation compromised the 2W group postweaning growth. Six weaning-weight groups were defined using a normal distribution: 4.6, 5.5, 6.4, 7.3, 8.2, and 9.5 kg. Pigs weighing 5.5 kg at 20 d of age were able to reach 125 kg 8 d sooner (168.8 d) than those weighing 4.6 kg (176.8 d). There was a linear relationship (P < 0.05) between weaning weight and ADG in the postnursery phase of growth. We conclude that 1) a weaning weight of less than 5.0 kg imposes the greatest marginal loss in production output for a 20-d weaning and 2) lactation length influences long-term growth, composition of growth, and viability of progeny. Key words: lifetime growth, swine lactation, weaning weight doi: 10.2527/jas.2009-2121

This study evaluated the combined effects of dietary CLA and supplemental fat (SF) source on organoleptic characteristics of bacon and pork loin samples in lean-genotype gilts (n = 144). Gilts (49.3 kg of BW) were randomly assigned to a 3 x 2 factorial design, consisting of SF [0% SF, 4% yellow grease (YG), or 4% tallow] and linoleic acid (LA; 1% corn oil or 1% CLA). Animals were slaughtered (113 kg) after a feeding period of 47 d. A trained sensory panel (n = 6 members) developed a flavor profile on commercially cured bacon samples (12 descriptors) and center-cut, boneless, pork loin chops (18 descriptors, using a 14-point, universal intensity scale). Bacon samples from pigs fed 4% SF were considered to have a sweeter flavor (4.07 [+ or -] 0.07) than those fed 0% SF (3.89 [+ or -] 0.07; P < 0.04). The intensity of salty flavor was greater in bacon samples from pigs fed LA (6.18 [+ or -] 0.09) compared with those fed CLA (5.86 [+ or -] 0.10; P < 0.04). The intensity of salty aftertaste of bacon was greater when LA was combined with YG (5.21 [+ or -] 0.14; P < 0.07) or tallow (5.44 [+ or -] 0.14; P < 0.01) than for LA alone (4.85 [+ or -] 0.14, but SF combined with CLA was not different from CLA alone (fat x LA; P < 0.02). Sour flavor intensity tended to be lower in loin samples from pigs fed CLA than for those fed LA (1.60 vs. 1.73 [+ or -] 0.06; P < 0.09). Samples from animals fed 4% tallow tended to have lower (P < 0.09) notes of astringent aftertaste (1.42 [+ or -] 0.08) compared with those fed 0% SF (1.62 [+ or -] 0.09) or 4% YG (1.66 [+ or -] 0.09). Overall, the flavor differences for bacon and loin samples were minimal, with most means differing by 1 point or less on the 14-point intensity scale. The sensory panel results indicate consumer acceptance of bacon and pork products from pigs fed CLA will not likely differ from commodity pork products. Key words: pork quality, conjugated linoleic acid, sensory analysis, supplemental fat, taste panel

Ontogeny and fatty acid chain-length specificity of gastrointestinal lipases in neonatal piglets were examined to explore the basis for variations in postnatal use of medium-chain triacylglycerols (MCT). Twenty-four newborn pigs were studied at 4 ages: 0, 6, 18, and 48 h postpartum (n = 6 pigs/age). Piglets were gastrically intubated and given 3.0 mmol/kg of B[W.sup.0.75] each of emulsified tri-C6:0 and tri-C8:0. One hour after intubation, the plasma concentration of C6:0 was 7.5-fold greater than that of C8:0 (P < 0.001), with total plasma medium-chain fatty acid concentrations 3.7-fold greater at 48 h than at 6 h of age (P < 0.05). Pancreatic, gastric, and lingual tissues were analyzed for lipase activity using an equimolar mixture of tri-C6:0 and triC8:0 as substrate. Pancreatic lipase activity averaged 7.0 [+ or -] 0.8 [micro]mol of fatty acid released/min per mg of protein for the medium-chain fatty acid substrates. Hexanoate (C6:0) release was greater at 0 h than at 6, 18, or 48 h (P < 0.05); however, age did not affect C8:0 release (P > 0.05). The lowest lipase activity was observed at 18 h for both tri-C6:0 and tri-C8:0. Chain-length specificity of pancreatic lipase was measured with tri-C4:0, tri-C6:0, tri-C8:0, and tri-C10:0 as combined or separate substrates. As separate substrates, the lipase activity decreased progressively as chain length increased from tri-C4:0 to tri-C10:0. As combined substrates, tri-C6:0 was hydrolyzed fastest (P < 0.05), followed by C4:0, C8:0, and C10:0. Gastric and lingual lipase activities averaged 2.7 nmol/min per mg of protein for the medium-chain fatty acid substrates, with hydrolysis of C6:0 being 7-fold greater than that of C8:0. In conclusion, pancreatic lipase dominates the preduodenal lipases in the neonatal pig, and greater activity of the gastrointestinal lipases toward tri-C6:0 underlies its increased rate of use. Key words: fat digestion, lipase, medium-chain triacylglycerol, ontogeny, pig

Four experiments were conducted to evaluate lipid digestibility in finishing swine fed chemically hydrogenated fats. Dietary chromic oxide was used as an inert marker to measure the apparent digestibility of supplemental fat (SF) that consisted of fully hydrogenated (FH), partially hydrogenated (PH), or PH products blended with other fat sources. In Exp. I, diets containing 5% SF (as-fed basis) comprising I00, 66.7, 33.3, or 0% FH animal fat (iodine value = 2.5), with the balance contributed by soy oil, were fed to gilts (n = 24). Apparent digestibility increased linearly (-12.0, 26.0, 61.2, and 72.6%; P < 0.001) as the amount of FH fat in the diet decreased, suggesting the digestibility of FH to be near zero. Experiment 2 (2 x 4 factorial; n = 48) evaluated diets containing 5% (as-fed basis) blended fat (FH tallow and yellow grease) to achieve iodine values of 20, 30, 40, or 50 compared with PH tallow with identical iodine values. Digestibility of diets formulated with PH tallow was greater than those containing blended fat (73.4 vs. 67.2%; P < 0.01), especially at lower iodine values (interaction; P < 0.10). In Exp. 3, digestibility was measured in pigs (n = 96) fed 5% (as-fed basis) PH choice white grease with iodine values of 20, 40, 60, or 80. Increasing iodine value did not alter digestibility (66.2, 69.2, 68.2, and 69.7%). Experiment 4 investigated digestibility (n = 32) of diets formulated with 8% (as-fed basis) PH fat (iodine value 20 or 50) with 0.10% lysolecithin as an emulsifier. Lipid digestibility was 14.5% greater in the 8% SF diet with an iodine value of 50 compared with the diet with an iodine value of 20 (79.15 vs. 69.12%; P < 0.001), but lysolecithin was without effect. These experiments indicate that partial hydrogenation is superior to blending unsaturated fat with saturated fat sources and that digestibility is not greatly affected by decreasing the iodine value via partial hydrogenation. Key Words: Digestibility, Supplemental Fat, Swine, Triglyceride

Previous research indicates that the neonatal pig does not alter feed intake in response to changes in the energy density of manufactured liquid diets. Also, the limited response of IGF-I to exogenous porcine ST (pST) previously observed in young pigs may be influenced by the source of dietary energy. Our objectives were to 1) determine the effect of a high-fat (HF; 25% fat and 4,639 kcal/kg ME; DM basis) or low-fat (LF; 2% fat and 3,481 kcal/kg ME; DM basis) manufactured liquid diet on pig performance; and 2) determine whether the limited response to exogenous pST in young pigs depends on the source of dietary energy. Two replicates of 60 pigs (n = 120; barrows and gilts distributed evenly), with an initial BW of 4,207 [+ or -] 51 g, were weaned from the sow at 10 d of age and used in a randomized complete block design. Pigs were assigned by BW to one of six pens. Diets were formulated to provide a constant lysine:ME ratio and were fed on a pen basis for a duration of 9 d. On d 5, barrows and gilts within a pen were assigned randomly to receive either 0 or 120 [micro]g of pST*kg [BW.sup.-1]*[d.sup.-1] for 4 d. Pigs gained 336 [+ or -] 9 g/d, which resulted in an ending BW of 7,228 [+ or -] 120 g, regardless of dietary treatment (P > 0.15). Pigs fed the LF diet consumed 17% more DM per pen daily than pigs fed the HF diet (2,777 [+ or -] 67 vs. 2,376 [+ or -] 67 g/d, P < 0.01), but calculated ME intake did not differ between dietary treatments (P > 0.20). The G:F was 24% greater in HF- than in LF-fed pigs (P < 0.01). Plasma urea N concentrations were higher in the HF-fed pigs (11.0 [+ or -] 0.6 mg/dL) than in pigs fed the LF diet (6.2 [+ or -] 0.6 mg/dL; P < 0.05). Treatment with pST increased circulating IGF-I (P < 0.01) and decreased PUN (P < 0.01) concentration 32 and 25%, respectively, regardless of dietary treatment (P > 0.30). Circulating leptin averaged 1.8 [+ or -] 0.1 ng/mL and was not affected by dietary treatment (P > 0.35) or pST (P > 0.40). These results suggest that the ST/IGF axis is responsive in the young pig and the increase in circulating IGF-I and growth is independent of the source of dietary energy. Also, young pigs respond to a lower energy density liquid diet with increased feed intake, without altering growth performance, apparently utilizing a mechanism other than circulating leptin. Key Words: Energy Source, Insulin-Like Growth Factor-I, Leptin, Somatotropin, Swine

Two experiments were conducted to evaluate the effect of lysolecithin on performance and nutrient digestibility of nursery pigs and to determine the effects of fat encapsulation by spray drying in diets fed in either meal or pelleted form. In Exp. 1, 108 pigs (21 d of age; 5.96 [+ or -] 0.16 kg BW) were allotted to one of four dietary treatments (as-fed basis): 1) control with no added lard, 2) control with 5% added lard, 3) treatment 2 with 0.02% lysolecithin, and 4) treatment 2 with 0.1% lysolecithin in a 35-d experiment. Added lard decreased ADG (P = 0.02) and ADFI (P < 0.06) during d 15 to 35 and overall. Lysolecithin improved ADG linearly (P = 0.04) during d 15 to 35 and overall, but did not affect ADFI or G:F. Addition of lard decreased the digestibility of DM (P = 0.10) and CP (P = 0.05) and increased (P = 0.001) fat digestibility when measured on d 10. Lysolecithin at 0.02%, but not 0.10%, tended to improve the digestibility of fat (P = 0.10). On d 28, digestibilities of DM, fat, CP, P, (P = 0.001), and GE (P = 0.03) were increased with the addition of lard, and lysolecithin supplementation linearly decreased digestibilities of DM (P = 0.003), GE (P = 0.007), CP, and P (P = 0.001). In Exp. 2, 144 pigs (21 d of age, 6.04 [+ or -] 0.16 kg BW) were allotted to one of six treatments in a 3 x 2 factorial randomized complete block design. Factors included 1) level (as-fed basis) and source of fat (control diet with 1% lard; control diet with 5% additional lard; and control diet with 5% additional lard from encapsulated, spray-dried fat) and 2) diet form (pelleted or meal). Addition of lard decreased feed intake during d 0 to 14 (P = 0.04), d 15 to 35 (P = 0.01), and overall (P = 0.008), and improved G:F for d 15 to 35 (P = 0.04) and overall (P = 0.07). Encapsulated, spray-dried lard increased ADG (P = 0.004) and G:F (P = 0.003) during d 15 to 28 compared with the equivalent amount of fat as unprocessed lard. Pelleting increased ADG (P = 0.006) during d 0 to 14, decreased feed intake during d 15 to 35 (P = 0.01), and overall (P = 0.07), and increased G:F during all periods (P < 0.02). Fat digestibility was increased (P = 0.001) with supplementation of lard, and this effect was greater when diets were fed in meal form (interaction, P = 0.004). Pelleting increased the digestibility of DM, OM, and fat (P < 0.002). Results indicate that growth performance may be improved by lysolecithin supplementation to diets with added lard and by encapsulation of lard through spray drying. Key Words: Digestibility, Emulsifier, Encapsulated Fat, Lysolecithin, Spray Drying, Swine

Typically, in vitro methods used for estimating the amount of ileal digestible AA do not exhaustively digest samples, and arbitrary methods for separating digestible from indigestible protein are used. This may lead to over- or underestimation of digestibility coefficients. A method that exhaustively digests proteins using pepsin and pancreatin was developed, and the first objective of this research was to confirm that exhaustive digestion was indeed appropriate and to determine the fractionation method for separating digestible from indigestible proteins. For this, three homoarginine-labeled animal proteins were prepared. Samples were subsequently digested in vivo and in vitro to determine which fraction should be considered indigestible, and in vitro followed by in vivo to determine whether the extent of digestion in vivo was improved by predigestion. In vivo, soluble but unabsorbed peptides were smaller than 1 kDa, suggesting that the size of soluble peptides is not what prevents their absorption. Thus, all in vitro-soluble proteins should be considered digestible. In vitro, 88 [+ or -] 3% of the soluble peptides were smaller than 1 kDa, with the remainder between 1 and 5 kDa, suggesting that in vitro digestion is less complete. Predigested samples were digested in vivo to the same size distribution as the nonpredigested samples. The second objective was to test whether in vitro digestibility assays based on these principles equaled in vivo digestibility. For this, digestibility data for 25 animal proteins were compared. Results showed a lack of correlation between lysine digestibility coefficients; however, across samples, the extent of digestion did not differ for lysine (P = 0.71), threonine (P = 0.26), methionine (P = 0.18), or valine (P = 0.66), whereas in vitro digestibility coefficients were lower for (the less water-soluble) histidine (P = 0.05), isoleucine (P < 0.01), leucine (P < 0.01), and phenylalanine (P = 0.05). In conclusion, in vitro digestibility assays should exhaustively digest proteins to mimic in vivo digestibility. All in vitro-soluble peptides could be considered digestible, because in vivo, no large soluble peptides were observed whose size prevented them from being absorbed. However, an in vitro assay based on these principles lacked precision for highly water-soluble AA, and underestimated digestibility for other AA. Better solubilization of the digesta and more replicates may improve the in vitro assay further. Key Words: Amino Acid Digestibility, Animal Protein, In Vitro, In Vivo

Pork quality is influenced by nutrition, genetics, management, and pork-processing procedures. Pigs of lean genotype fed diets high in unsaturated fat may have thinner, lower-quality bellies with a soft fat composition. Therefore, we investigated the effects of supplementing 5% choice white grease that had been chemically hydrogenated to iodine values of 80, 60, 40, or 20 on pork quality. Diets were fed to barrows and gilts of two genotypes (NPD [Ham-line x Manor hybrid] and PIC [406, 419, or 420 x C22]; n = 240) in a 4 x 2 x 2 factorial design. Pigs (76.8 kg of mean initial weight) were placed on test at a common age and were fed dietary treatments for 52 d. Pigs of PIC genotype were heavier at trial initiation, had higher feed intake and feed conversion ratio (F/G; P < 0.05), and greater backfat (26.3 vs. 24.0 mm; P < 0.001) and loin depth (59.0 vs. 55.3 mm; P < 0.001) compared with the NPD genotype pigs. As the iodine value of dietary fat was reduced, belly thickness increased (P < 0.05) and length decreased linearly (P < 0.05). Congruently, belly fat iodine value decreased from 73.9 to 67.4 (linear effect; P < 0.001) and belly fat C18:2 concentration declined from 20.6 to 16.3% (linear and quadratic effect; P < 0.001). The belly mono- and polyunsaturated fat ratio increased 29% as diet iodine value declined from 80 to 20 (linear and quadratic effect; P < 0.001). Further, there was a linear increase (P < 0.001) in saturated fatty acid concentration of belly fat (C14:0, C16:0, and C18:0) as dietary fat iodine value declined. Quadratic (P < 0.005) effects were detected in the level of C18:1trans as iodine value decreased from 80 to 20, paralleling dietary content. Dietary fat iodine value did not affect fat digestibility, ADFI, or F/G. Pork belly quality was improved as defined by reduced iodine value, C18:2 content, increased saturated fatty acid content, increased thickness, and decreased length as dietary iodine value decreased. Results indicate that reduction of dietary fat iodine value by chemical hydrogenation has the desirable effect of improving pork quality and does not alter growth performance. Key Words: Fatty Acids, Hydrogenated Fats, Meat Quality, Pork, Pigs

Interest in fortification of human foods, including pork, with conjugated linoleic acid (CLA) is growing and may provide benefits as a neutraceutical based on research evaluating CIA as an anticarcinogen, immune modulator, antiatherogenic agent and a body composition modulator. This study evaluated the combined effects of dietary CIA and supplemental fat source on growth, fatty acid composition and belly quality of lean genotype gilts (n = 144). Pigs (49.3 kg) were randomly assigned to six diets (3 x 2 factorial) varying in supplemental fat (none, 4 g/100 g yellow grease or 4 g/100 g tallow) and linoleic acid [1 g/100 g corn oil (CO) or 1 g/100 g CLA (CLA-60)] for 47 d. Both the cis-9, trans-11 and the trans-10, cis-12 isomers of CIA were increased in belly and longissimus fat depots from pigs fed CLA, and that increase was up to 92% greater when CIA was fed with 4 g/100 g supplemental fat (fat source x linoleic acid interaction, P < 0.05). Pigs fed CIA had a greater concentration of 18:0 and less 18:1 cis-9 (P < 0.01) in various fat depots, suggesting a reduction in [[DELTA].sup.9] desaturase activity. The iodine value of belly fat from pigs consuming tallow and CIA combined was reduced to 62.0 from an initial value of 70.4. CLA supplementation also increased belly weights (P < 0.05). CIA did not affect longissimus muscle area, backfat depth and the percentage of fat-free lean (P > 0.10), but it increased the subjective intramuscular fat score by 18.8% (P < 0.01). In conclusion, CLA enrichment of pork products may be enhanced when combined with additional supplemental dietary fat, and together with tallow can be used to increase the saturated fatty acid content of pork. KEY WORDS: * conjugated linoleic acid * fatty acid composition * pork * supplemental fat * swine

Two experiments investigated the quantitative relationship between dietary fat and fatty acid composition of pork. Experiment 1 was designed to establish the rate of decline for linoleic acid and iodine value of pork fat during the late fattening phase following a dietary reduction. Gilts (n = 288) were fed diets varying in linoleic acid content from 4.11 to 1.56% for 4, 6, or 8 wk prior to slaughter. The maximum rate of decline was 2% 18:2 per week and 2.5 iodine value units per week. Experiment 2 evaluated the effects of dietary fat source and level on carcass fatty acid composition and on pork quality characteristics. Barrows (n = 147) and gilts (n = 147) were allocated to seven dietary treatments for the last 6 wk of the finishing phase. Diets contained 0, 2.5, or 5% dietary fat comprised of 100, 50, or 0% beef tallow. The balance was provided by animal-vegetable blended fat. As the level of tallow increased there was a linear decrease (P < 0.05) in 18:2 content and iodine value of carcass fat. Conversely, 16:1 and 18:1 increased linearly (P < 0.05) as tallow increased. However, 16:1 decreased linearly (P < 0.05) as level of fat increased. As the level of tallow was increased a greater reduction in 18:2 and iodine value was observed in diets with 5% dietary fat compared to diets with 2.5% fat (P < 0.05). These results indicate that reduction of dietary PUFA content had the desired effect of lowering 18:2 content and iodine value of pork fat and that significant alterations could be elicited in as little as 6 to 8 wk of feeding. Key Words: Pigs, Carcass Quality, Fatty Acids, Supplemental Fat, Linoleic Acid

The purpose of this study was to examine the effect of 0-50 [micro]mol/L trans-10, cis-12 conjugated linoleic acid (CLA) and cis-9, trans-11 CLA isomers on lipid and glucose metabolism in cultures of differentiating 3T3-L1 preadipocytes. Specifically, we investigated the effects of 6 d of CLA treatment on the following: 1) [sup.14]C-glucose and [sup.14]C-oleic acid incorporation and esterification into lipid; 2) [sup.14]C-glucose and [sup.14]C-fatty acid oxidation; and 3) basal and isoproterenol-stimulated lipolysis. Trans-10, cis-12 CLA supplementation (25 and 50 [micro]mol/L) increased both [sup.14]C-glucose and [sup.14]C-oleic acid incorporation into the cellular lipid fraction, which was primarily triglyceride (TG), compared with bovine serum albumin (BSA) controls. Although glucose oxidation ([sup.14]C-glucose to [sup.14]C-C[O.sub.2]) was unaffected by CLA supplementation, oleic acid oxidation ([sup.14]C-oleic acid to [sup.14]C-C[O.sub.2]) was increased by ~55% in the presence of 50 [micro]mol/L trans-10, cis-12 CLA compared with BSA controls. In contrast, 50 [micro]mol/L linoleic acid (LA) and cis-9, trans-11 CLA-treated cultures had ~50% lower C[O.sub.2] production from [sup.14]C-oleic acid compared with control cultures after 6 d of fatty acid exposure. Finally, 50 [micro]mol/L trans-10, cis-12 CLA modestly increased basal, but not isoproterenol-stimulated lipolysis compared with control cultures. Thus, the TG-lowering actions of trans-10, cis-12 CLA in cultures of 3T3-L1 preadipocytes may be via increased fatty acid oxidation, which exceeded its stimulatory effects on glucose and oleic acid incorporation into lipid. KEY WORDS: * conjugated linoleic acid * preadipocytes * glucose and fatty acid oxidation * glucose and fatty acid incorporation * lipolysis

Feeding manufactured liquid diets to early-weaned pigs improves growth performance and reduces days to market weight compared with pigs receiving pelleted dry feed. Few alternative dietary ingredients are utilized in manufactured liquid diets other than byproducts of the dairy industry, especially for sources of carbohydrates. This experiment was designed to evaluate the efficacy of starch from partially hydrolyzed corn syrup solids (CSS), at two different levels of hydrolyzation, as a replacement for lactose in manufactured liquid diets. Forty-eight pigs were removed from sows at 1 d of age and randomly assigned to one of three treatments: 1) control with lactose as the carbohydrate source, 2) lactose replaced (gram for gram) with CSS (dextrose equivalent [DE]-20), and 3) lactose replaced with DE-42. In addition, 10 pigs were randomly removed from several litters to provide estimates of initial body composition and small intestinal variables. Twenty-four pigs were removed from the study on d 10 of treatment, and the remaining 24 pigs were removed on d 20 of treatment. Pigs averaged 9,845 [+ or -] 191 g at d 20 of treatment regardless of dietary treatment (P > 0.20). No differences in ADG, ADFI, or feed efficiency were detected between treatment groups from d 0 to 20 (P > 0.19). Whole-body water, protein, lipid, and ash accretion rates were unaffected by dietary treatment from d 0 to 10 or from d 0 to 20 (P > 0.20). The replacement of lactose with CSS did not affect intestinal villi height or width, or crypt depth (P > 0.10). Pigs fed lactose tended to have greater lactase activity on d 10 than pigs fed CSS (P < 0.07). Also, pigs fed lactose tended to have lower oligosaccharidase activity than pigs fed the DE-20 diet on d 20 (P < 0.07). No other differences in lactase, maltase, or long oligosaccharidase specific activity on d 10 or 20 of treatment were detected (P > 0.12). Plasma urea nitrogen concentrations were unaffected by diet on d 10 and 20 of treatment. In addition, dry matter digestibility of the diets averaged approximately 85.6 [+ or -] 0.8% and was unaffected by dietary treatment or day of treatment. These results suggest that partially hydrolyzed CSS can be used as a replacement for lactose in manufactured liquid diets for neonatal pigs. Key Words: Carbohydrates, Newborn Animals, Nutrient Physiology, Pigs, Small Intestine

In a field trial conducted on a commercial swine farm, lean-genotype sows (n = 485) were fed diets containing 0 or 10% supplemental fat as either medium-chain triglyceride or choice white grease from d 90 of gestation until weaning (15.5 d). Effects on standard sow and litter production traits were examined together with assessment of sow body condition using live ultrasound. Daily feed intake during lactation was 10% higher in sows consuming diets without added fat (7.2 vs 6.5 kg; P < 0.01); however, lactation ME (23.9 Mcal/d) and digestible lysine (54 g/d) intakes were unaffected (P > 0.10). Sows supplemented with fat were 4 kg heavier on d 109 of gestation (220 vs 224 kg; P [less than or equal to] 0.01), 1 d after farrowing (210 vs 214 kg; P [less than or equal to] 0.01), and at weaning (210 vs 214 kg; P [less than or equal to] 0.01). Expressed as overall gain, this amounted to a 23% increase (0.66 vs 0.86 kg/d; P [less than or equal to] 0.01) and was accompanied by a 49% increase in backfat (0.82 vs 1.68 mm; P [less than or equal to] 0.03) from d 90 to farrowing. Changes in sow weight (-0.01 kg/d) and backfat (+4.2 mm) over lactation were minimal and were not affected by fat supplementation (P [greater than or equal to] 0.10). Longissimus muscle area at weaning was slightly greater (44.96 vs 46.2 [cm.sup.2]) in sows consuming fat than in control sows (P [less than or equal to] 0.05), but changes in longissimus muscle area were not significant from d 90 to weaning (P [greater than or equal to] 0.10). Gestation length, pigs born alive, average birth weight, survival (d 3 to weaning), and days to estrus were not affected by diet (P > 0.10). However, supplemental fat increased pig ADG (192 vs 203 g/d; P < 0.01) and average pig weaning weight (4.3 vs 4.5 kg) at 15.5 d (P [less than or equal to] 0.02). No differences between the two fat sources were detected. This large-scale study demonstrated that supplemental fat during gestation and lactation effectively improved sow condition and improved suckling pig performance without affecting energy intake during lactation, implying improved efficiency of sow energy utilization. Key Words: Growth, Lactation, Medium-Chain Triacylglycerols, Pigs, Reproductive Efficiency

We conducted an experiment to determine the effects of dietary copper (Cu) source and level on carcass characteristics, longissimus muscle fatty acid composition, and serum and muscle cholesterol concentrations in steers. Sixty Angus and Angus x Hereford steers were stratified by weight and initial liver Cu concentration within a breed and randomly assigned to treatments. Treatments consisted of: 1) control (no supplemental Cu); 2) 20 mg Cu/kg DM from Cu sulfate (CuSO(sub 4)); 3) 40 mg Cu/kg DM from CuSO(sub4); 4) 20 mg Cu/kg DM from Cu citrate; 5) 20 mg Cu/kg DM from Cu proteinate; and 6) 20 mg Cu/kg DM from tribasic Cu chloride. A corn silage-soybean meal-based diet was fed for 56 d. Steers were then switched to a high-concentrate diet. Equal numbers (n = 5) of steers per treatment were slaughtered after receiving the finishing diets for either 101 or 121 d. Serum cholesterol was not affected by treatment during the growing phase but was decreased (P < .05) in steers supplemented with Cu by d 84 of the finishing period and remained lower (P Key Words: Copper, Steers, Cholesterol, Fatty Acids

Hepatocytes isolated from sheep were incubated in the presence of reduced phenolics and glycine to determine the effects of these compounds on hepatic propionate metabolism in vitro. 3-Phenylpropionic (PPA) or t-cinnamic (CA) acids, but not benzoic (BA) or 3-(4-hydroxyphenyl)propionic (4OHPPA) acids, decreased conversion of propionate to glucose at .05 mM in the absence of supplemental glycine. At 1.2 mM, all reduced phenolics decreased conversion of propionate to glucose in the absence of supplemental glycine. Addition of glycine to the incubation medium linearly alleviated the inhibition by BA, PPA, or CA, suggesting that physiological glycine concentrations limited alleviation of inhibition of propionate metabolism. Hippuric acid production increased as glycine concentration increased in the presence of PPA, CA, or 4OHPPA. Bovine serum albumin did not alleviate inhibition of conversion of propionate to glucose caused by BA, PPA, or CA and slightly alleviated inhibition caused by 4OHPPA (.4 mM). Of the reduced phenolics tested, PPA is the most likely to inhibit gluconeogenesis from propionate in ovine liver in vivo. Key Words: Propionates, Phenolic Acids, Liver Cells, Sheep, Gluconeogenesis

Two experiments were conducted to evaluate the effects of inducing premature parturition on the composition of colostrum and milk and the effects of dietary fat supplementation on colostrum and milk composition from premature and delayed farrowing sows. In Trial 1, eight sows were allowed to farrow naturally (d 114, NF sows) and eight sows were induced to farrow (IF sows) prematurely by injection of prostaglandin [F.sub.2[Alpha]] on d 112 of gestation. Average fat content of sow's milk during the first 12 h postpartum was lower for IF than for NF sows (P < .05), as was overall mean fat percentage (P < .05). In Trial 2, 53 sows were randomly assigned in a 2 (diets) x 5 (parturition treatments) factorial experiment. Dietary treatments fed during the last 2 wk of gestation and throughout lactation were control diet and added fat diet (control diet plus 10% corn oil). Parturition treatments included 1) natural farrowing (d 114), induction of parturition with prostaglandin [F.sub.[Alpha]] on 2) d 110, 3) d 111, or 4) d 112 of gestation, and 5) delay of parturition with progesterone followed by injection of prostaglandin on d 115. The added fat diet increased milk fat percentage compared with the control diet (P < .01). Colostral fat percentage was reduced by induction of premature farrowing (d 110 or 111) in sows fed the control diet but was unaffected in sows fed added dietary fat (interaction, P < .05). Mean fat content of colostrum was not reduced in groups receiving the added fat diet that were induced to farrow prematurely. In sows with delayed parturition, colostral immunoglobulin G concentrations were lower for the group fed the added fat diet than for the group fed the control diet (P < .05). Addition of fat to sow diets during late gestation and lactation may help maintain high colostral energy for newborn pigs when sows are induced to farrow prematurely. Key Words: Sows, Colostrum, Milk, Parturition, Dietary Fat, Reproduction

In vitro measurements of metabolism were made in subcutaneous and perirenal adipose tissue (AT) and liver from prenatally androgenized ewe lambs (TE), control ewe lambs (CE), and control wether lambs (CW). In adipose tissue slices, release of glycerol or fatty acids into the medium was not different among treatments, but glycerol release was greater (P < .01) from subcutaneous AT than from perirenal AT. Basal fatty acid release and the free fatty acid pool were greater (P < .05) for perirenal AT than for subcutaneous AT; fatty acid release and the fatty acid response (increased NEFA in media and tissue) were increased more by lipolytic stimuli in subcutaneous AT than in perirenal AT. Adipose tissue from CW had the greatest (P < .05) fatty acid response under conditions of near-maximal stimulation; rates from TE were intermediate to those from CW and CE. Incorporation of glucose into fatty acids and glycerol in subcutaneous AT was lowest (P < .05) for TE. Oxidation of glucose and acetate to C[O.sub.2] and incorporation of acetate into fatty acids or glycerol in subcutaneous AT, glucose and acetate metabolism inperirenal AT, and cellularity measurements for both AT did not differ among treatments. In liver slices, oxidation of [1-14C]propionate to C[O.sub.2] was greater (P < .05) for CE than for TE or CW, and gluconeogenic capacity from [1-14C]propionate tended to be greater (P < .10) for CE than for TE. Glucose and C[O.sub.2] production from [2-14C]propionate, [U-14C]alanine, or [U-14C]glycerol and total and peroxisomal first cycle of [Beta]-oxidation of [1-14C]palmitate were not altered by prenatal androgenization or sex. There were no effects (P > .1) of prenatal exposure to testosterone on mitochondrial protein content of liver, rates of mitochondrial state 3 or state 4 respiration, the ratio of ADP:oxygen in the presence of respiratory substrates, or hepatic contents of lipid, triglyceride, or glycogen. Protein content of liver was greater (P < .05) for CW than for CE; TE were intermediate. Collectively, there were minimal modifications of in vitro metabolism in AT or liver attributable to prenatal androgenization or sex that would directly influence ADG and carcass composition. Key Words: Pregnancy, Testosterone, Lambs, Adipose Tissue, Liver, Metabolism

Piglets (n = 240, 11.0 [+ or -] 0.1 d old, 3.93 [+ or -] 0.05 kg) were allotted to one of four treatments in a 2 x 2 factorial arrangement to examine the effects of diet physical form and nursery environment during the first 14 d after weaning on growth to market weight. During the treatment period, pigs were housed (10 pigs/ pen) in either a conventional hot nursery (30[degrees]C) or a segregated-temperature nursery (cool ambient temp. of 24[degrees]C, with enclosed hot-box hovers at 32[degrees]C). Pigs in each environment were fed nutritionally identical diets in either liquid or dry-pellet form for 14 d. Subsequently, all pigs were fed identical dry diets and were housed in common grower-finisher facilities (penned by sex, five pigs/pen). At the end of the treatment period (d 14), pigs fed the liquid diet were 21% heavier than pigs fed the dry pellet diet (9.22 vs 7.60 kg; P [is less than] 0.001). Similarly, gain, feed intake, and gain/feed of liquid-fed pigs were 44%, 18%, and 22% greater, respectively, than observed for pigs fed the dry pellet diet. No main effect of environment was observed (P [is greater than] 0.10); however, an interaction with diet physical form occurred during the early-nursery period (P [is less than] 0.01). Pigs fed the liquid diet showed better performance in the conventional nursery, whereas pigs fed the dry pellet diet were favored in the segregated-temperature nursery. No major differences in growth performance or in ultrasound carcass measurements were detected during the growing-finishing period; however, the advantage in body weight of liquid-fed pigs gained during the first 2 wk postweaning was maintained to the end of the trial (113.9 vs 110.6 kg; P [is less than] 0.05). Pigs that were fed the early-nursery diet in liquid form reached market weight (110 kg) 3.7 d sooner than the dry-fed controls (P [is less than] 0.01). Estimates of lean gain (calculated from live ultrasound data) were unaffected, suggesting that composition of growth was not altered. Collectively, these results show that liquid feeding during early life can markedly accelerate piglet growth performance and that the growth advantage is maintained to market weight, with no evidence of compensatory gain in the dry-fed control pigs. Key Words: Environment, Growth, Liquid Diets, Pigs

An experiment was conducted to determine the effects of Cu and soybean oil (SBO) supplementation on ruminal and tissue lipid metabolism and carcass characteristics in finishing steers. Sixty Angus steers (369.0 [+ or -] 10.1 kg) were stratified by weight and randomly assigned to treatments in a 2 x 2 factorial arrangement, with factors being 0 or 20 mg of supplemental Cu/kg DM from Cu sulfate and 0 or 4% SBO. Steers were fed a high-concentrate basal diet that contained 5.3 mg Cu/kg DM. Average daily gain and feed intake were reduced (P [is less than] 0.01) by SBO but were not affected by Cu. Gain:feed ratio was not affected by treatment. Liver Cu concentrations were higher (P [is less than] 0.01) in steers receiving supplemental Cu and lower (P [is less than] 0.04) in SBO-supplemented steers. Copper supplementation tended to reduce (P [is less than] 0.12) and SBO supplementation tended to increase (P [is less than] 0.11) serum cholesterol concentrations. Backfat depth was reduced (P [is less than] 0.10) by Cu and SBO supplementation. Marbling scores and longissimus muscle lipid content were not affected by Cu supplementation; however, SBO supplementation reduced (P [is less than] 0.01) marbling scores. Longissimus muscle polyunsaturated fatty acids tended to be increased (P [is less than] 0.14) in Cu-supplemented steers. Longissimus muscle C 18-conjugated dienes and the 18:1 trans isomer were increased (P [is less than] 0.05) in SBO-supplemented steers. Ruminal fluid 18:3 was increased (P [is less than] 0.05) and the 18:1 trans isomer was decreased (P [is less than] 0.05) in Cu-supplemented steers. These results indicate that as little as 20 mg of supplemental Cu/kg DM can reduce backfat and may alter lipid metabolism in steers fed high-concentrate diets. Key Words: Cholesterol, Copper, Fatty Acids, Steers