Animal-vegetable Fat Research Articles

The effects of adding fat to diets of lactating dairy cows on total-tract neutral detergent fiber digestibility: A meta-analysis

The objective of this meta-analysis was to determine the effects of supplemental fat on fiber digestibility in lactating dairy cattle. Published papers that evaluated the effects of adding fat to the diets of lactating dairy cattle on total-tract neutral detergent fiber digestibility (ttNDFd) and dry matter intake (DMI) were compiled. The final data set included 108 fat-supplemented treatment means, not including low-fat controls, from 38 publications. The fat-supplemented treatment means exhibited a wide range of ttNDFd (49.4% ± 9.3, mean ± standard deviation) and DMI (21.3 kg/d ± 3.5). Observations were summarized as the difference between the treatment means for fat-supplemented diets minus their respective low-fat control means. Additionally, those differences were divided by the difference in diet fatty acid (FA) concentration between the treatment and control diets. Treatment means were categorized by the type of fat supplement. Supplementing 3% FA in the diet as medium-chain fats (containing predominately 12- and 14-carbon saturated FA) or unsaturated vegetable oil decreased ttNDFd by 8.0 and 1.2 percentage units, respectively. Adding 3% calcium salts of long-chain FA or saturated fats increased ttNDFd by 3.2 and 1.3 percentage units, respectively. No other fat supplement type affected ttNDFd. Except for saturated fats and animal-vegetable fats, supplementing dietary fat decreased DMI. When the values for changes in ttNDFd are regressed on changes in DMI there was a positive relationship, though the coefficient of determination is only 0.20. When changes in ttNDFd were regressed on changes in DMI, within individual fat supplement types, there was no relationship within calcium salt supplements. There was a positive relationship between changes in ttNDFd and changes in DMI for saturated fats. Neither relationship suggested that the increased ttNDFd with calcium salts or saturated FA was due to decreased DMI for these fat sources. A subset of the means included measured ruminal neutral detergent fiber digestion. Analysis of this smaller data set did not suggest that ruminal neutral detergent fiber digestibility is depressed by fat supplementation more than ttNDFd. Adding fats, other than those with medium-chain FA, consistently increased digestible energy density of the diet. However, due to reduced DMI, this increased energy density may not result in increased digestible nutrient intake.

Interaction of unsaturated fat or coconut oil with monensin in lactating dairy cows fed 12 times daily. I. Protozoal abundance, nutrient digestibility, and microbial protein flow to the omasum

Monensin (tradename: Rumensin) should reduce the extent of amino acid deamination in the rumen, and supplemental fat should decrease protozoal abundance and intraruminal N recycling. Because animal-vegetable (AV) fat can be biohydrogenated in the rumen and decrease its effectiveness as an anti-protozoal agent, we included diets supplemented with coconut oil (CNO) to inhibit protozoa. In a 6 × 6 Latin square design with a 2 × 3 factorial arrangement of treatments, 6 rumen-cannulated cows were fed diets without or with Rumensin (12g/909kg) and either no fat (control), 5% AV fat, or 5% CNO. The log10 concentrations (cells/mL) of total protozoa were not different between control (5.97) and AV fat (5.95) but were decreased by CNO (4.79; main effect of fat source). Entodinium and Dasytricha decreased as a proportion of total cells from feeding CNO, whereas Epidinium was unchanged in total abundance and thus increased proportionately. Total volatile fatty acid concentration was not affected by diet, but the acetate:propionate ratio decreased for CNO (1.85) versus control (2.95) or AV fat (2.58). Feeding CNO (23.8%) decreased ruminal neutral detergent fiber digestibility compared with control (31.1%) and AV fat (30.5%). The total-tract digestibility of NDF was lower for CNO (45.8%) versus control (57.0%) and AV fat (54.6%), with no difference in apparent organic matter digestibility (averaging 69.8%). The omasal flows of microbial N and non-ammonia N were lower for CNO versus control and AV fat, but efficiency of microbial protein synthesis was not affected. The dry matter intake was 4.5kg/d lower with CNO, which decreased milk production by 3.1kg/d. Main effect means of dry matter intake and milk yield tended to decrease by 0.7 and 1.2kg/d, respectively, when Rumensin was added. Both percentage and production of milk fat decreased for CNO (main effect of fat source). An interaction was observed such that AV decreased milk fat yield more when combined with Rumensin. Using large amounts of supplemental fat, especially CNO, to decrease abundance of protozoa requires further research to characterize benefits versus risks, especiallywhen combined with Rumensin.

Interaction of unsaturated fat or coconut oil with monensin in lactating dairy cows fed 12 times daily. II. Fatty acid flow to the omasum and milk fatty acid profile

Feeding animal-vegetable (AV) fat or medium-chain fatty acids (FA) to dairy cows can decrease ruminal protozoal counts. However, combining moderate to large amounts of AV fat with monensin (tradename: Rumensin, R) could increase the risk for milk fat depression (MFD), whereas it is not known if diets supplemented with coconut oil (CNO; rich in medium-chain FA) with R would cause MFD. In a 6 × 6 Latin square design with a 2 × 3 factorial arrangement of treatments, 6 rumen-cannulated cows were fed diets without or with R (12 g/909kg) and either control (no fat), 5% AV fat, or 5% CNO. Diets were balanced to have 21.5% forage neutral detergent fiber, 16.8% crude protein, and 42% nonfiber carbohydrates. Omasal flows of FA were characterized by an increased percentage of trans 18:1 for AV fat and CNO diets compared with the control, a higher percentage of 12:0 and 14:0 for CNO, and higher cis 18:1 for AV fat. Milk FA composition reflected the changes observed for omasal FA digesta flow. The de novo FA synthesis in the mammary gland was decreased by the main effects of R compared without R (averaged over fat treatments) and for added fat (AV fat and CNO) versus control (averaged over R). The percentages of 6:0, 8:0, and 10:0 in milk fat were lower for R and for AV fat and CNO compared with the control. The percentage of trans 18:1 FA in milk fat also higher for AV fat and CNO compared with the control. Against our hypotheses, the feeding of CNO did not prevent MFD, and few interactions between R and fat source were detected. The feeding of CNO did compromise ruminal biohydrogenation, with accumulation of trans 18:1 in the rumen and in milk fat.

Sow and litter response to supplemental dietary fat in lactation diets during high ambient temperatures1

The objective of this experiment was to determine the impact of supplemental dietary fat on total lactation energy intake and sow and litter performance during high ambient temperatures (27 ± 3°C). Data were collected from 337 mixed-parity sows from July to September in a 2,600-sow commercial unit in Oklahoma. Diets were corn-soybean meal-based with 7.5% corn distillers dried grains with solubles and 6.0% wheat middlings and contained 3.24 g of standardized ileal digestible Lys/Mcal of ME. Animal-vegetable fat blend (A-V) was supplemented at 0, 2, 4, or 6%. Sows were balanced by parity, with 113, 109, and 115 sows representing parity 1, 2, and 3 to 7 (P3+), respectively. Feed disappearance (subset of 190 sows; 4.08, 4.18, 4.44, and 4.34 kg/d, for 0, 2, 4, and 6%, respectively; P < 0.05) and apparent caloric intake (12.83, 13.54, 14.78, and 14.89 Mcal of ME/d, respectively; P < 0.001) increased linearly with increasing dietary fat. Gain:feed (sow and litter BW gain relative to feed intake) was not affected (P = 0.56), but gain:Mcal ME declined linearly with the addition of A-V (0.16, 0.15, 0.15, and 0.14 for 0, 2, 4, and 6%, respectively; P < 0.01). Parity 1 sows (3.95 kg/d) had less (P < 0.05) feed disappearance than P2 (4.48 kg/d) and P3+ (4.34 kg/d) sows. Body weight change in P1 sows was greater (P < 0.01) than either P2 or P3+ sows (-0.32 vs. -0.07 and 0.12 kg/d), whereas backfat loss was less (P < 0.05) and loin depth gain was greater (P < 0.05) in P3+ sows compared with P1 and P2 sows. Dietary A-V improved litter ADG (P < 0.05; 1.95, 2.13, 2.07, and 2.31 kg/d for 0, 2, 4, and 6% fat, respectively) only in P3+ sows. Sows bred within 8 d after weaning (58.3, 72.0, 70.2, and 74.7% for 0, 2, 4, and 6%, respectively); conception rate (78.5, 89.5, 89.2, and 85.7%) and farrowing rate (71.4, 81.4, 85.5, and 78.6%) were improved (P < 0.01) by additional A-V, but weaning-to-breeding interval was not affected. Rectal and skin temperature and respiration rate of sows were greater (P < 0.002) when measured at wk 3 compared with wk 1 of lactation, but were not affected by A-V addition. Parity 3+ sows had lower (P < 0.05) rectal temperature than P1 and P2 sows, and respiration rate was reduced (P < 0.001) in P1 sows compared with P2 and P3+ sows. In conclusion, A-V improved feed disappearance and caloric intake, resulting in improved litter weight gain and subsequent reproductive performance of sows; however, feed and caloric efficiency were negatively affected.

Investigating unsaturated fat, monensin, or bromoethanesulfonate in continuous cultures retaining ruminal protozoa. I. Fermentation, biohydrogenation, and microbial protein synthesis

Methane is an end product of ruminal fermentation that is energetically wasteful and contributes to global climate change. Bromoethanesulfonate, animal-vegetable fat, and monensin were compared with a control treatment to suppress different functional groups of ruminal prokaryotes in the presence or absence of protozoa to evaluate changes in fermentation, digestibility, and microbial N outflow. Four dual-flow continuous culture fermenter systems were used in 4 periods in a 4×4 Latin square design split into 2 subperiods. In subperiod 1, a multistage filter system (50-μm smallest pore size) retained most protozoa. At the start of subperiod 2, conventional filters (300-μm pore size) were substituted to efflux protozoa via filtrate pumps over 3 d; after a further 7 d of adaptation, the fermenters were sampled for 3 d. Treatments were retained during both subperiods. Flow of total N and digestibilities of NDF and OM were 18, 16, and 9% higher, respectively, for the defaunated subperiod but were not different among treatments. Ammonia concentration was 33% higher in the faunated fermenters but was not affected by treatment. Defaunation increased the flow of nonammonia N and bacterial N from the fermenters. Protozoal counts were not different among treatments, but bromoethanesulfonate increased the generation time from 43.2 to 55.6h. Methanogenesis was unaffected by defaunation but tended to be increased by unsaturated fat. Defaunation did not affect total volatile fatty acid production but decreased the acetate:propionate ratio; monensin increased production of isovalerate and valerate. Biohydrogenation of unsaturated fatty acids was impaired in the defaunated fermenters because effluent flows of oleic, linoleic, and linolenic acids were 60, 77, and 69% higher, and the ratio of vaccenic acid:unsaturated FA ratio was decreased by 34% in the effluent. This ratio was increased in both subperiods with the added fat diet, indicating an accumulation of intermediates of biohydrogenation. However, the flow of 18:2 conjugated linoleic acid was unaffected by defaunation or by treatments other than added fat. The flows of trans-10, trans-11, and total trans-18:1 fatty acids were not affected by monensin or faunation status.

Potato Chip Scraps in Diets for Broiler Chicks

Rahnema, S., Lilburn, M. and Nixon, J. 2004. Potato chip scraps in diets for broiler chicks. J. Appl. Anim. Res., 25: 1–4. A 21-d preliminary experiment was conducted to study the effect of including different amounts of potato chip scraps (PCS, 0, 5, 7.5%) in broiler chicks (n=100; 37g) allocated to 18 pens. In treatment 1 (control),' chicks were fed a corn and soybean meal-based diet supplemented to meet NRC (1994) requirements. In treatments 2 and 3, 5% and 7.5% of PCS was substituted for corn, salt and animal-vegetable fat keeping all diets isocaloric and isonitrogenous. At 21-d, there was increased feed intake with each level of supplemental PCS and this was reflected in a linear increase in average daily gain. There were no significant differences in feed efficiency suggesting that the positive effect associated with PCS was due to increased feed consumption. This experiment demonstrated that PCS up to 7.5% of the diet might safely be fed to day-old broiler chicks to 3 weeks of age.

Compartmental modeling with nitrogen-15 to determine effects of degree of fat saturation on intraruminal N recycling.

Two- and three-compartment models were developed to describe N kinetics within the rumen using three Holstein heifers and one nonlactating Holstein cow fitted with ruminal and duodenal cannulas. A 4 x 4 Latin square design included a control diet containing no supplemental fat and diets containing 4.85% of diet dry matter as partially hydrogenated tallow (iodine value = 13), tallow (iodine value = 51), or animal-vegetable fat (iodine value = 110). Effects of fat on intraruminal N recycling and relationships between intraruminal N recycling and ruminal protozoa concentration or the efficiency of microbial protein synthesis were determined. A pulse dose of 15(NH4)2SO4 was introduced into the ruminal NH3 N pool, and samples were taken over time from the ruminal NH3 N and nonammonia N pools. For the three-compartment model, precipitates of nonammonia N after trichloroacetic acid and ethanol extraction were defined as slowly turning over nonammonia N; rapidly turning over nonammonia N was determined by difference. Curves of 15N enrichment were fit to models with two (NH3 N and nonammonia N) or three (NH3 N, rapidly turning over nonammonia N, and slowly turning over nonammonia N) compartments using the software SAAM II. Because the three-compartment model did not remove a small systematic bias or improve the fit of the data, the two-compartment model was used to provide measurements of intraruminal N recycling. Intraruminal NH3 N recycling (45% for control) decreased linearly as fat unsaturation increased (50.2, 43.0, and 41.7% for partially hydrogenated tallow, tallow, and animal-vegetable fat, respectively). Intraruminal nitrogen recycling was not correlated with efficiency of microbial protein synthesis or ruminal protozoa counts.

Effects of degree of fat saturation on fiber digestion and microbial protein synthesis when diets are fed twelve times daily.

Three Holstein heifers and one nonlactating cow, fitted with ruminal and duodenal cannulas, were arranged in a 4 x 4 Latin square design to determine the effects of degree of fat saturation on ruminal neutral detergent fiber digestion and microbial protein synthesis and to determine whether changes in the efficiency of microbial protein synthesis were related to protozoal populations in the rumen. Corn silage-based diets contained no added fat or 4.85% of diet dry matter as partially hydrogenated tallow, tallow, or animal-vegetable fat. Iodine values of fat sources were 12.8, 50.6, and 109.7 for partially hydrogenated tallow, tallow, and animal-vegetable fat, respectively. Cattle were fed every 2 h and consumed 1.5% of body weight as dry matter daily. Ruminal neutral detergent fiber digestibility was decreased by added fat but was not affected by increasing iodine value. Flows of microbial N and non-NH3-nonmicrobial N to the duodenum were not affected by treatment. Ruminal protozoa concentration decreased linearly as the iodine value of fats increased. The efficiency of microbial protein synthesis was increased and protozoa concentrations tended to decrease when fat was fed. Decreased ruminal protozoa concentration may have decreased intraruminal N recycling. Biohydrogenation of added fat may result in a low ruminal concentration of unsaturated fatty acids when cows are fed frequently, reducing the negative effects of unsaturated fat sources on ruminal neutral detergent fiber digestibility. Protozoa were inhibited by unsaturated fat, but it is not clear if biohydrogenation and frequent feeding lessened inhibition.

Effects of feeding high carbohydrate or high fat diets. 1. Growth and metabolic status of the posthatch poult following immediate or delayed access to feed

Three experiments were conducted with turkey poults to determine the effects of diet and delayed placement on growth and selected aspects of carbohydrate metabolism. Immediately after hatch, poults were placed in batteries and allowed either immediate access to feed and water (FED) or feed and water withdrawal for 48 h (WH). In the first two experiments, diets contained a high proportion of carbohydrate from corn (CHO; 60% of diet) or a lower proportion of corn (26%) and 10% supplemental animal-vegetable fat (FAT). The WH poults weighed less than FED poults at 5 d postfeeding (DPF; P < or = 0.05) but not at 13 DPF. Similarly, poults fed the CHO diet were heavier 5 DPF, whereas poults fed the FAT diet were heavier at 13 DPF (P < or = 0.05). Regardless of feeding regimen (WH vs FED), all poults were nearly depleted of hepatic glycogen prior to feeding. At 2 DPF, poults fed the CHO diet had more hepatic glycogen concentrations compared with those fed the FAT diet (P < or = 0.002). In addition, one-half of the WH poults fed the CHO diet had plasma glucose concentrations in excess of 500 mg/dL at 2 DPF. In Experiment 3, similar feeding regimens and diets were used with the addition of a third diet containing a synthetic medium-chain triglyceride emulsion (MCT) as the supplemental fat source. Poults fed the FAT and MCT diets were 41 g heavier than poults fed the CHO diet at 13 DPF (P < or = 0.05). Similar to the results of Experiment 2, poults fed the CHO diet had increased hepatic glycogen concentrations at 2 DPF, and within the WH treatment at 2 DPF, 30% of the poults had plasma glucose concentrations in excess of 500 mg/dL. Metabolic consequences of delayed placement were also found. At both 4 and 7 DPF, WH poults had a reduced capacity for glucose clearance 60 min after a glucose load (250 mg; P < or = 0.05). The current experiments demonstrate that supplemental fat may ease the metabolic shift toward glycolysis after hatching, thereby improving growth through 2 wk of age.

Effects of Various Added Dietary Fat Sources, Anatomical Location, and Sex on Intramuscular Fatty Acid Profiles of Growing-Finishing Swine1,2

Intramuscular (i.m.) adipose tissue samples were taken from the deep pectoral (DP), Longissimus (ML), and Gluteus medius (GM) of 96 barrows (n = 48) and gilts (n = 48) in four replications to evaluate the effects of various dietary fat sources, anatomical location and sex on fatty acid profiles of growing-finishing pigs. Dietary treatments were: 1) control (C); 2) 40% rice bran (RB); 3) 10% poultry fat (PF); 4) 10% lard (L); 5) 10% restaurant grease (RG); and 6) 10% animal-vegetable fat blend (A). Water and diets were provided for ad libitum consumption from 25kg to slaughter (105kg BW). Pigs were humanely slaughtered, chilled, and i.m. samples collected at 24h post-mortem. Then i.m. samples were extracted and methylated and total myristic, palmitic, palmitoleic, stearic, oleic, linoleic, linolenic, saturated fatty acids (SFA), monounsaturated fatty acids (MFA), and monounsaturated:saturated ratios (M:S) and sex differences were determined. Feeding PF or L increased (P<0.01) the i.m. adipose tissue M:S 11 and 22%, respectively, when compared with pigs fed C diet. Pigs fed C diet were highest (P<0.01) in i.m. SFA when compared with pigs fed RB, PF, L, RG, or A. Samples taken from the ML were highest (P<0.002) in SFA when compared with i.m. adipose tissue taken from DP or GM. Additionally, GM was higher (P<0.04) in MFA and M:S than ML. Thus, this study shows although there are differences among locations within a pig, feeding diets with added PF or L provides a means of alleviating human health concerns associated with high intake of saturated fat.

Influence of dietary levels of fat, fiber, and copper sulfate and fat rancidity on cecal activity in the growing turkey

Two experiments were conducted with 6- to 10-wk-old turkeys. In Experiment 1, 6-wk-old turkeys were fed diets varying in level of fat (4.4 to 10%) or fiber (2.5 to 9.0%). The diets also contained extra copper as copper sulfate at either 0.1 or 0.2% of the diet. At 8 wk of age, 15 replicate birds were housed in individual cages and all excreta was collected. Excreta was separated as being “regular” or “cecal” in origin based on appearance. At 10 wk of age, 10 birds per treatment were killed and cecal contents removed under anaerobic conditions. Cecal contents were assayed for various nutrients and viscosity was measured. In a second comparable study, turkeys were fed animal-vegetable fat or regular or rancid canola oil (60.25 vs 120.24 ng/g malonaldehyde, respectively). In Experiment 1, feeding copper sulfate had the most noticeable effect on various cecal parameters. There was an increase (P < 0.01) in dry matter cecal droppings produced and the cecal contents were of increased viscosity (P < 0.05). Copper had no effect on pH or microbial colony count of the cecal contents. Feeding copper resulted in a significant increase in the high molecular weight (> 300,000) fraction of cecal contents and this fraction was of higher viscosity. Feeding copper sulfate resulted in a dramatic increase in copper content of cecal contents (280 to 11,848 ppm), although the copper content of regular excreta was also increased (17 to 1,008 ppm). The various levels of fiber and fat generally had no effect on cecal parameters. Feeding rancid canola oil did result in increased viscosity of cecal contents, compared to the situation seen with fresh canola oil. Fat rancidity per se, however, failed to influence other parameters such as total mass of cecal material produced and composition of cecal material. Feeding copper sulfate or rancid fat will increase the viscosity of cecal material, which may contribute to litter management problems.

Fatty Acid Digestion in Lactating Dairy Cows Fed Fats Varying in Degree of Saturation and Different Fiber Sources

Six cannulated cows were assigned to six treatments in a 6 × 6 Latin square design to evaluate the effects of fat saturation and amount and source of effective fiber on fatty acid metabolism. Cows were fed a control diet with no added fat or diets with 5% added fat from saturated tallow, tallow, or animal-vegetable fat; the diets with animal-vegetable fat had three percentages of effective fiber: 40% forage, 40% forage plus 20% soyhulls, or 60% forage. Cows fed diets supplemented with fat tended to have more disappearance of total fatty acids in the rumen than did those fed the control diet. Disappearance of fatty acids from the rumen, especially C16 and C18, was higher for cows fed the low fiber diet. The apparent digestibility of fatty acids in the small intestine was higher for cows fed the control diet than for those fed supplemental fat. Apparent digestibility also was reduced as fat saturation increased, primarily because of saturated tallow. Digestibility of C18:1 in saturated tallow was reduced, apparently in association with other saturated fatty acids. Fiber source had no effects on apparent intestinal digestibility of fatty acids. Concentrations of C18:0 and C18:1 in milk fat increased as the degree of fat saturation decreased, reflecting higher unsaturated C18 intake and ruminal biohydrogenation of polyunsaturated C18 fatty acids.

Effects of Supplemental Dietary Fat on Growth and Carcass Characteristics of Growing-Finishing Swine

AbstractAn experiment consisting of six dietary treatments in four replications: 1) control (C); 2) 40% rice bran (RB); 3) 10% poultry fat (PF); 4) 10% lard (L); 5) 10% restaurant grease; and 6) 10% animal-vegetable fat blend (AV), was conducted to evaluate the effects of dietary energy on growth and carcass characteristics of growing-finishing pigs. Ninety-six crossbred pigs (48 barrows and 48 gilts) weighing approximately 25kg were blocked on sex, weight, and litter, then assigned to treatments and fed their respective diets until slaughter at 105kg. Pigs fed added dietary fat had improved ADG, FE, and lower ADFI (p<0.05) compared to those fed C or RB.Barrows grew faster (p<0.05) than gilts regardless of treatment. Pigs fed added fat had more backfat, lower percentage lean cuts, and a higher dressing percentage (p<0.05) than those fed C or RB. Pigs fed RB had a higher (p<0.05) 15min post-mortem pH than those fed PF, RG, or AV, but pH taken at 30 and 45min and 1.0, 1.5, 2.0, and 24.0h was not different (p>0.05). No differences were observed for ham or loin color, ham or loin firmness, loin marbling, or water holding capacity. Added dietary fat will improve performance without affecting pork quality; however, a decrease in percentage lean can be expected.

Utilization of Hydrolyzed Sucrose Polyester (Olestra) in Broiler Diets

Three experiments were conducted in which hydrolyzed olestra (HO) and hydrolyzed olestra manufacturing by-product (HBP) were compared with corn oil (CO) and a feed-grade hydrolyzed animal-vegetable fat blend (AVF) as fat supplements in diets for broilers. Various blends of HO and HBP with AVF and other fat sources were also evaluated. Results of these experiments indicate that HO or HBP may be used as energy sources in broiler diets. Use of these materials as the sole source of supplemental fat often reduced body weight gain and impaired feed utilization as compared with CO or AVF; however, when used as a component of a blended fat product typical of industry supplements, there was little if any adverse effect on live performance. Carcass fatty acid content was a reflection of dietary fat content. If the blend of fats containing HO or HBP contains a suitable ratio of unsaturated and saturated fatty acids, the product should be an acceptable source of supplemental energy in broiler diets.

Comparison of Two Blended Animal-Vegetable Fats Having Low or High Free Fatty Acid Content

A study was conducted to compare the feeding value of two blended animal-vegetable fats having different levels of free fatty acids (FFA) but similar fatty acid profiles and unsaturated:saturated (U:S) fatty acid ratios. One contained 29.8% FFA (AV-LO), while the other contained 44.7% FFA (AV-HI). Poultry oil (PO) and corn oil (CO) were fed as reference standards. Diets had 4, 6, or 8% supplemental CO, adjusting nutrient levels to dietary energy. Other fat sources were substituted for CO on a wt/wt basis. Each treatment was fed to four replicate pens of fifty male broilers from day-old to 42 days of age.There were no significant differences between the two blended fat sources in body weight, feed utilization, calorie:gain ratio, or mortality at 21 or 42 days of age. Body weight of birds fed the two blended fat sources was significantly less than that of birds fed PO at 21 days, but did not differ significantly at 42 days of age. Results of this study indicate that blended animal-vegetable fats with fatty acid profiles and U:S ratios similar to PO resulted in similar performance; the FFA level of these blended fats did not adversely influence performance of the broilers.

Influence of Supplemental Dietary Fat on Changes in Vitamin E Concentration in Livers of Poults

An experiment was conducted to determine the influence of supplemental dietary fat on α-tocopherol (TOC) stored in the livers of young turkeys during the first 21 d after hatching. The four dietary treatments were obtained by supplementing a corn-soybean meal diet with 8% sucrose (SUC), 8% animal-vegetable fat (AVF), 8% tallow (TAL), or 8% coconut oil (COC). All diets were supplemented with 12 IU of dl-α-tocopheryl acetate (vitamin E)/kg of diet. Body weight at 21 d of age was not affected by dietary fat, whereas feed efficiency was improved (P < .05) by added fat, irrespective of source. Liver TOC (micrograms per gram of liver and micrograms per total liver weight) decreased markedly between 1 to 14 d of age, irrespective of fat source. Average TOC concentration in liver was 78.9 μg/g at 1 d, but was only .5 μg/g at 14 d. Between 14 and 21 d of age, total liver TOC increased slightly in all treatment groups. No diet effect was observed on the liver TOC concentration until 21 d of age. At this time, poults fed TAL had less (P < .05) TOC in liver than those fed COC and AVF. The data show that neither the presence of supplemental dietary fat nor fat source changed the pattern of marked decrease in liver TOC during the first 14 d after hatching.

Effects of Fat Saturation and Source of Fiber on Site of Nutrient Digestion and Milk Production by Lactating Dairy Cows1,2

Six primiparous cannulated cows were assigned to six treatments in a 6×6 Latin square design to evaluate the effects of degree of fat saturation and amount and source of effective fiber on site of nutrient digestion and milk production. Cows were fed for ad libitum intake a control diet with no added fat or diets with 5% added fat from saturated tallow, tallow, or animal-vegetable fat; the diets with animal-vegetable fat had 40% forage, 40% forage plus 20% soyhulls, or 60% forage. Ruminal acetate:propionate was higher when soyhulls replaced forage NDF because of the higher digestibility of soyhulls in the rumen and total tract. Ruminal digestion of NDF was decreased as unsaturation of fat increased. True and apparent efficiencies of bacterial protein synthesis were increased as fat unsaturation increased, probably because of reduced recycling of microbial N in the rumen. The digestibility of fatty acids in the small intestine was higher in cows fed no fat than in those fed fat and was reduced as fat unsaturation decreased, primarily because of the saturated tallow. Dry matter intake was decreased 14% by increased fat unsaturation. All fat supplements depressed milk protein percentage. Production of 4% FCM tended to decrease linearly as unsaturation of fat increased. In diets with 5% added fat, a degree of saturation between saturated tallow and tallow (iodine values of 18 and 62) appears to be optimum for fatty acid digestibility and DMI.

Assessment of the Effects of Iodine Value on Fatty Acid Digestibility, Feed Intake, and Milk Production

Data were pooled from 11 studies evaluating supplemental fat sources differing primarily in degree of saturation (tallow, animal-vegetable fat, vegetable oil. and hydrogenated fats). Data were standardized as proportions of the respective controls to reduce variation among individual studies and were subjected to stepwise multiple regression against the iodine value of fats, the percentage increases of total fatty acids in diets above the respective controls, or the ratio of total C16 to C18 fatty acids in fats (only for hydrogenated fats). Increased iodine value (increasing unsaturation) of fats increased apparent fatty acid digestibility, especially as iodine value increased from 11 to 27. For partially hydrogenated fat sources, as the ratio of C16 to Cl8 fatty acids increased, digestibility also increased, especially with increasing iodine value (positive interaction). Beneficial effects of higher C16:C18 ratio were reduced as amount of added fat increased (negative interaction). Dry matter intake and FCM production decreased as iodine value increased, perhaps because of inhibition of fiber digestion or metabolic regulation of DMI. Milk protein percentage depression averaged .2 percentage units for most fats. However, as partially hydrogenated fat sources became more saturated, milk protein depression appeared to be less evident; increased ratio of C16:C18 of fatty acids appeared to increase milk protein percentage. Despite the lower apparent digestibility of fatty acids of hydrogenated fats, increased milk production and percentages of fat and protein appeared to make them more economical than more unsaturated fats.

Dietary Carnitine Did Not Influence Performance and Carcass Composition of Broiler Chickens and Young Turkeys Fed Low- or High-Fat Diets

Two experiments were conducted to determine the influence of supplemental dietary carnitine on performance and carcass composition of young turkeys and broiler chickens. Experiments 1 and 2 were done with poults to 21 d of age and broilers to 45 d of age, respectively. Three dietary concentrations of L-carnitine (0, 50, or 100 mg/kg) were fed in a factorial arrangement with two concentrations of animal-vegetable fat (A-V fat), 2.25 or 8% in Experiment 1 and 1 or 5% in Experiment 2. L-Carnitine did not affect (P > .05) BW gain or feed efficiency in either experiment, irrespective of concentration of dietary fat. Similarly, proximate composition of 21-d-old poults and 45-d-old broilers was not changed by L-carnitine. Increasing levels of fat supplementation improved feed efficiency of poults and improved 45-d BW and feed efficiency of broilers. Carcass fat of poults and broilers was increased (P ≤ .05) by supplemental fat at the expense of carcass water and protein.

Site of mineral absorption in lactating cows fed high-fat diets.

Five lactating Holstein cows with ruminal and duodenal cannulas were used in a 5 x 5 Latin square to determine the site of mineral absorption and effects of sources and amount of dietary fat on apparent absorption. Cows were fed (DM, 17.4 +/- .8 kg/d) chopped alfalfa hay, alfalfa haylage, corn silage, and concentrate at 1:1:1:2 (DM) at 12-h intervals. Calcium salts of palm fatty acid distillate (CS) or animal-vegetable (AV) fat were 0% (control), 2.5% (low, L), or 5.0% (high, H) of the diet DM. After 2 wk of adaptation, duodenal and fecal grab samples were collected at 7-h intervals for 5 d and composited by animal. Calcium intake increased (P < .05) with high-fat diets (195 vs 170 g/d), whereas Mg intake remained unchanged (54.3 +/- 9.0 g/d). Apparent absorption, estimated by Cr2O3, was regressed on Ca or Mg intake (grams/day) and fatty acid (FA) intake (grams/day). Total absorption of Ca (grams/day) = -37.4 + .264 Ca (P = .07, R2 = .14). Ruminal absorption of Mg was independent of FA intake, and magnesium was secreted posterior to the duodenum. Total tract Mg absorption (grams/day) was described by -7.685 + .464 Mg -.0044 FA (P < .0005, R2 = .46). Fat intake decreased (P < .05) total tract Mg absorption, and Ca absorption was decreased by high fat compared with low fat intake (P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)