G. Cherian

Dietary CLA alters yolk and tissue FA composition and hepatic histopathology of laying hens.

The effect of dietary CLA along with n-3 PUFA on yolk FA profile and hepatic lipid accumulation was investigated. Laying hens (n=40) were randomly assigned to four experimental diets containing 0, 0.5, 1.0, or 2.0% CLA. Menhaden oil was used as the source of n-3 PUFA. Dietary CLA did not affect the total lipid content of egg yolk (P>0.05). The amounts of CLA isomers (cis-9 trans-11, trans-10 cis-12) in the egg yolk were proportional to the levels of CLA in the diet (P<0.05). The total CLA content in the egg yolk was 0, 0.97, 2.4, and 5.3 wt%, respectively (P<0.05). Addition of CLA resulted in an increase in saturated FA (P<0.05) with a concomitant reduction in monounsaturated FA (P<0.05) in the yolk, liver, abdominal fat, breast, and thigh muscle. No difference in saturated and monounsaturated FA content in heart and spleen tissue was noted. Dietary CLA at all concentrations resulted in an increase (P<0.05) in the total number of fat vacuoles and lipid infiltration in hepatocytes. The number of cells with 75% or higher lipid vacuolation in the cytoplasm was also increased (P<0.05) by 2.0% CLA. Dietary CLA at 0.5% levels resulted in an increase (P<0.05) in the total lipid content of hepatic tissue. The total lipid content in leg muscle was lower (P<0.05) in CLA-fed birds. However, no effect of CLA on lipid content of breast muscle, heart, spleen and adipose tissue was observed (P>0.05). The current study used CLA in a FFA form. The effects of using CLA in other form such as TG on avian hepatic tissue need to be investigated.

Egg Quality and Yolk Polyunsaturated Fatty Acid Status in Relation to Broiler Breeder Hen Age and Dietary n-3 Oils

The effects of broiler breeder hen age and dietary n-3 oils on yolk n-3 and n-6 fatty acid composition, egg quality, fertility, and hatchability were investigated. A total of 2,200 eggs were collected from wk 26 through 62 from Cobb breeder hens fed diets containing 1.75% fish oil + 1.75% yellow grease (low n-3) or 3.5% fish oil (high n-3). Eggs obtained from a commercial source were used as the control for n-6 and n-3 fatty acid composition and hatchability studies. A significant decrease in egg weight, yolk weight, shell weight, and yolk color was observed for high n-3 when compared with low n-3 eggs (P < 0.05). No difference was noted in egg total fat content due to dietary treatments. However, egg fat was highest at 42 wk for high and low n-3 eggs when compared with other weeks (P < 0.05). Total n-3 fatty acids, docosahexaenoic acid (DHA, 22:6 n-3), and the DHA:arachidonic acid (AA, 20:4 n-6) ratios were higher in high n-3 eggs when compared with low n-3 eggs. The incorporation of DHA was lowest at wk 26 and highest at wk 38 for low and high n-3 eggs (P < 0.05). Low n-3 and high n-3 eggs at the oldest age had the highest level of AA (P < 0.05). A positive correlation between hen age and egg yolk AA content was observed. The r(2) values for AA in low n-3 and high n-3 eggs were 0.91 and 0.90, respectively (P < 0.05). The total content of long-chain (>18-C) n-6 PUFA (AA+ 22:4 n-6+22:5 n-6) constituted over 0.3 g per commercial egg when compared with 0.09 and 0.07 g in low and high n-3 eggs, respectively. The content of DHA in commercial eggs was negligible (<0.5%) when compared with low and high n-3 (P < 0.05). The overall fertility was 98.6 and 97.4%, and hatchability of fertile eggs was 80 and 83.8% for low and high n-3 eggs, respectively (P > 0.05). The overall fertility was 96%, and hatchability of fertile eggs was 80% for commercial eggs.

Oxidative stability and lipid components of eggs from flax-fed hens: Effect of dietary antioxidants and storage

An experiment was conducted to investigate the effect of dietary antioxidants and storage on fatty acid profile, oxidative stability, and vitamin E concentration of n-3 fatty acid-enriched eggs. Eggs (384, 48/diet) were collected from ISA Brown layers fed diets containing corn-soy (control) with 100 g/kg of flax seed and 2 types of antioxidants [alpha-tocopherols (alpha-TOC) and butylated hydroxytoluene (BHT)] at 0, 50, 100, or 150 IU or mg/kg. Eggs were stored at 4 degrees C. On d 0, 20, 40, and 60 of storage, 2 eggs were selected randomly from each replicate (totaling 12 eggs per treatment) and analyzed. Eggs from hens fed flax had increased alpha-linolenic (18:3n-3), eicosapentaenoic (20:5n-3), and docosahexaenoic acids (DHA, 22:6n-3) and decreased arachidonic acid (20:4n-6) and total n-6:n-3 ratio when compared with control eggs (P<0.05). The n-6:n-3 fatty acid ratio was lowest in the flax+50 IU of alpha-TOC, flax+100 IU of alpha-TOC, and flax+BHT supplemented group when compared with the flax group (P<0.05). With the exception of flax+100 mg of BHT, addition of antioxidants led to a reduction in palmitic acid in fresh eggs (P<0.05). During the first 20 d of storage, over a 17% reduction in total n-3 fatty acids was observed in eggs from flax+50 mg of BHT supplemented groups (P<0.05). Docosahexaenoic acid was the predominant long-chain n-3 fatty acid in egg and was stable during storage in the control, flax, flax+100 IU of alpha-TOC, flax+150 IU of alpha-TOC, and flax+150 mg of BHT groups. However, antioxidant supplementation had no effect on DHA upon storage in flax+50 IU of alpha-TOC and flax+50 mg of BHT eggs where over 13 to 17% reduction in DHA content was observed during 20 to 60 d of storage (P<0.05). Inclusion of alpha-TOC led to over 4.5- to 12-fold increases in alpha-TOC in eggs. Egg storage for 40 d or longer led to over 50% reduction in egg alpha-TOC (P<0.05). Feeding flax seeds led to an increase in TBA reactive substances in eggs (P<0.05). alpha-Tocopherol was better in preventing lipid oxidation than BHT at d 0 of storage. However, neither had a significant effect on egg TBA reactive substances upon 60 d of storage (P>0.05). These studies demonstrate that the level and type of antioxidants and duration of egg storage significantly affected the fatty acid profile, alpha-TOC status, and oxidative stability of chicken eggs.

Hepatic lipid characteristics and histopathology of laying hens fed CLA or n−3 fatty acids

The effect of dietary CLA and n−3 PUFA on hepatic TAG accumulation, histopathology, and FA incorporation in lipid classes by laying chickens was investigated. One hundred twenty 30-wk-old single-comb white leghorn laying hens were distributed randomly to four treatments (3 replications of 10 birds) and were fed diets containing CLA and animal fat (Diet I), 18∶3n−3 (Diet II), or long-chain n−3 FA (Diet III). A sunflower oil (n−6 FA)-based diet was the control. Feeding Diet I resulted in an increase in hepatic total lipids (P<0.05). The liver TAG content was 32.2, 18.9, 29.4, and 18.7 mg/g for hens fed Diet I, Diet II, Diet III, and the control diet, respectively (P<0.05). The serum TAG was lowest in bilds fed Diet II (P<0.05). Diet I resulted in an increase in the total number of fat vacuoles and lipid infiltration in hepatocytes (P<0.05). The number of cells with 75% or higher lipid vacuolation was observed only in birds fed Diet I. Feeding diets containing CLA resulted in an increase in the content of the c9,t11 CLA isomer in liver TAG and PC (P<0.05). No difference was observed in the CLA concentration of hepatic PE fractions. The content of DHA (22∶6n−3) was higher in the TAG, PC, and PE of hens fed Diet II and Diet III than Diet I and the control (P<0.05). Feeding CLA resulted in an increase in total saturated FA in the TAG and PC fractions (P<0.05). Long-term feeding of CLA in laying birds leads to an increase in liver TAG and may predispose birds to fatty liver hemorrhagic syndrome.

Effect of flaxseed supplementation rate and processing on the production, fatty acid profile, and texture of milk, butter, and cheese

Health and nutrition professionals advise consumers to limit consumption of saturated fatty acids and increase the consumption of foods rich in n-3 fatty acids. Researchers have previously reported that feeding extruded flaxseed, which is high in C18:3n-3, improves the fatty acid profile of milk and dairy products to less saturated fatty acids and to more C18:3n-3. Fat concentrations in milk and butter decreased when cows were fed higher concentrations of extruded flaxseed. The objective of this study was to determine the optimal rate of flaxseed supplementation for improving the fatty acid profile without decreasing production characteristics of milk and dairy products. By using a double 5 × 5 Latin square design, 10 mid- to late-lactation Holstein cows were fed extruded (0, 0.91, 1.81, and 2.72 kg/d) and ground (1.81 kg/d) flaxseed as a top dressing for 2-wk periods each. At the end of each 2-wk treatment period, milk and serum samples were taken. Milk was subsequently manufactured into butter and fresh Mozzarella cheese. Increasing supplementation rates of extruded flaxseed improved the fatty acid profile of milk, butter, and cheese gradually to less saturated and atherogenic fatty acids and to more C18:3n-3 by increasing concentrations of C18:3n-3 in serum. The less saturated fatty acid profile was associated with decreased hardness and adhesiveness of refrigerated butter, which likely cause improved spreadability. Supplementation rates of extruded flaxseed did not affect dry matter intake of the total mixed ration, milk composition, and production of milk, butter, or cheese. Flaxseed processing did not affect production, fatty acid profile of milk, or texture of butter and cheese. Feeding up to 2.72 kg/d of extruded flaxseed to mid- to late-lactation Holstein cows may improve nutritional and functional properties of milk fat without compromising production parameters.

Long-term effects of feeding flaxseeds on hepatic lipid characteristics and histopathology of laying hens

The long-term effects of dietary flaxseed and tocopherols on hepatic and blood plasma lipids, fatty acids, tocopherols, hepatic TBA reactive substances, and histopathology of Brown Leghorn hens were investigated. Thirty-two-week-old ISA Brown Leghorn hens (n = 120) were kept in cages and were fed 1 of the 3 corn-soybean meal-based diets, a control diet (no flax) or a 10% flax diet with or without 100 IU of tocopherols, until the hens were 64 wk of age. Feeding diets with 10% flaxseed reduced hepatic and plasma fat content, hepatic triglycerides, total number of fat vacuoles, and number of cells with 75% or higher lipid infiltration in hepatocytes (P < 0.05). Addition of tocopherols to the 10% flax diet increased hepatic and plasma tocopherol content. A significant reduction in hepatic TBA reactive substances was observed in the hens supplemented with the basal diet with 10% flax and 100 IU of tocopherols (P < 0.05). Feeding diets containing flaxseed resulted in an increase in the content of alpha-linolenic (18: n-3) and docosahexaenoic acids (22:6n-3), with a concomitant reduction in monounsaturated and saturated fatty acids in the hen liver and plasma. Overall, long-term feeding of hens with flax led to a reduction in liver and plasma lipids and reduced hepatocellular infiltration. Inclusion of tocopherols may be needed to reduce lipid oxidation products in the liver of flax-fed hens. However, tocopherol supplementation had no effect on hepatocellular lipid infiltration or liver total lipid or triglyceride content.

Hatching egg and newly hatched chick yolk sac total IgY content at 3 broiler breeder flock ages

During the first week of the posthatching period, before the immune system is mature enough to produce its own B lymphocytes, a chicks humoral immunity depends on maternal antibodies (IgY) received from the egg yolk. During incubation and after hatching, the yolk sac (YS) membrane transfers nutrients (including IgY) from the egg yolk to the developing embryo or newly hatched chick. The objective of this study was to determine the effects of breeder flock age on the total IgY content of egg yolks and chick YS from a commercial broiler breeder strain. Hatching eggs from the same broiler breeder flock were collected at 32, 40, and 55 wk of age. One group of eggs per flock age was used to determine the egg yolk total IgY content. Another group of eggs was incubated for 21.5 d, and upon hatching, the YS of newly hatched chicks were collected to determine the total IgY content. Egg and egg yolk weight increased with flock age, but YS weights did not reflect egg yolk weight. The total IgY content per gram of egg yolk increased with flock age; this fact plus the observed yolk weight increase with flock age notably increased the total IgY contained in yolks of eggs laid by 55-wk-old breeders. However, chicks hatching from 55-wk-old breeders had less IgY per gram of YS than chicks from 32- and 40-wk-old breeders. Whether there are differences in the rates of YS absorption between chicks of different breeder ages is unknown. This research provided total IgY values for broiler breeder egg yolk and chick YS of a commonly used meat-type chicken strain. Differences in egg yolk and YS total IgY contents due to flock age in this type of bird had not been previously reported. Research on the physiological consequences of YS absorption rates in chicks from different breeder ages is advised.

Maternal dietary n-3 fatty acids alter cardiac ventricle fatty acid composition, prostaglandin and thromboxane production in growing chicks

The effects of feeding n-6 and n-3 fatty acids to broiler hens on cardiac ventricle fatty acid composition, and prostaglandin E2 (PGE2) and thromboxane A2 (TXA2) production of hatched chicks were investigated. Fertile eggs obtained from hens fed diets supplemented with 3.5% sunflower oil (Low n-3), 1.75% sunflower+1.75% fish oil (Medium n-3), or 3.5% fish oil (High n-3) were incubated. The hatched chicks were fed a diet containing 18:3 n-3, but devoid of longer chain n-6 and n-3 fatty acids for 42 days. Arachidonic acid content was lower in the cardiac ventricle of High n-3 and Medium n-3 compared to Low n-3 birds for up to 2 weeks (P<0.002). Long chain n-3 fatty acids were higher in the cardiac ventricle of chicks from hens fed High and Medium n-3 diets when compared to chicks from hens fed the Low n-3 diet. Differences in long chain n-3 fatty acids persisted up to four weeks of age (P<0.001). Peripheral blood mononuclear cells (PBMNC) of 7-day-old High n-3 broilers produced significantly lower PGE2 and TXA2 than PBMNC from Low n-3 and Medium n-3 birds. These results indicate that maternal dietary n-3 fatty acids increases cardiac ventricle n-3 fatty acids while reducing arachidonic acid and ex vivo PGE2 and TXA2 production during growth in broiler chickens.

Egg yolk omega-6 and omega-3 fatty acids modify tissue lipid components, antioxidant status, and ex vivo eicosanoid production in chick cardiac tissue

The effects of maternal n-6 and n-3 fatty acid (FA) supplementation on hatched chick tissue FA profile, antioxidant status, and ex vivo eicosanoid production by the cardiac tissue were investigated. Eggs with low, medium, and high levels of n-3 FA were obtained by feeding Cobb breeder hens were fed a corn-soybean meal-based diet containing 3.5% sunflower oil (low n-3), 1.75% sunflower oil plus 1.75% fish oil (medium n-3), or 3.5% fish oil (high n-3). Total n-3 FA in the yolk ranged from 1.8, 10.3, and 13.3% for low, medium, and high n-3 eggs, respectively (P < 0.001). Total long-chain (>20 C) n-6 FA in the egg yolk were 7.4, 2.1, and 1.3 for low n-3, medium n-3, and high n-3 eggs, respectively (P < 0.001). No differences were observed in total fat content of the eggs, which was 33.3, 31.6, and 31.9% for low n-3, medium n-3, and high n-3 eggs, respectively (P > 0.05). Hatchability for the low, medium, and high n-3 eggs was 89, 85, and 83%, respectively (P > 0.05). The total lipid content of chick liver, heart, brain, and lungs can be placed in the following descending order: liver > brain > heart > lung and was not affected by egg FA (P > 0.05). Total n-3 FA were higher in the tissues of medium and high n-3 chicks than in the tissue of low n-3 chicks (P < 0.05). There was no effect of egg FA on docosahexaenoic acid (22:6n-3) in the heart of low, medium, and high n-3 chicks (P > 0.05). There were no differences in total glutathione, glutathione peroxidase, glutathione reductase, or superoxide dismutase activities in the tissues of chicks from low n-3, medium n-3, and high n-3 eggs (P > 0.05). The medium n-3 and high n-3 chicks had lower catalase activity in the heart than did the low n-3 chicks (P = 0.013). The TBA reactive substances were significantly lower in the liver of high n-3 chicks than in that of low and medium n-3 chicks (P < 0.05). Heart tissue prostaglandin E(2) concentration was higher in low n-3 chicks than in those hatched from medium or high n-3 eggs (P < 0.05). Heart tissue thromboxane A(3) was lowest in low n-3 chicks (P < 0.05). There was no effect of yolk FA on ex vivo prostaglandin E(3) or thromboxane A(2) production in cardiac tissue (P > 0.05). These results indicate that modulating egg yolk n-3 FA enhances tissue n-3 FA and reduces proinflammatory cardiac eicosanoid production without affecting hatchability.

Maternal dietary conjugated linoleic acid alters hepatic triacylglycerol and tissue fatty acids in hatched chicks

The effects of feeding CLA to hens on newly hatched chick hepatic and carcass lipid content, liver TAG accumulation, and FA incorporation in chick tissues such as liver, heart, brain, and adipose were studied. These tissues were selected owing to their respective roles in lipid assimilation (liver), as a major oxidation site (heart), as a site enriched with long-chain polyunsaturates for function (brain), and as a storage depot (adipose). Eggs with no, low, or high levels of CLA were produced by feeding hens a corn-soybean meal-basal diet containing 3% (w/w) corn oil (Control), 2.5% corn oil +0.5% CLA oil (CLA1), or 2% corn oil +1.0% CLA oil (CLA2). The egg yolk content of total CLA was 0.0, 1.0, and 2.6% for Control, CLA1, and CLA2, respectively (P<0.05). Maternal dietary CLA resulted in a decrease in chick carcass total fat (P<0.05). Liver tissue of CLA2 chicks had the lowest fat content (P<0.05). The liver TAG content was 8.2, 5.8, and 5.1 mg/g for Control, CLA1, and CLA2 chicks, respectively (P<0.05). The chicks hatched from CLA1 and CLA2 incorporated higher levels of cis-9,trans-11 CLA in the liver, plasma, adipose, and brain than Control (P<0.05). The content of 18∶0 was higher in the liver, plasma adipose, and brain of CLA1 and CLA2 than Control (P<0.05), but no difference was observed in the 18∶0 content of heart tissue. A significant reduction in 18∶1 was observed in the liver, plasma, adipose, heart, and brain of CLA1 and CLA2 chicks (P<0.05). DHA (22∶6n−3) was reduced in the heart and brain of CLA1 and CLA2 chicks (P<0.05). No difference was observed in carcass weight, dry matter, or ash content of chicks (P>0.05). The hatchabilities of fertile eggs were 78, 34, and 38% for Control, CLA1, and CLA2, respectively (P<0.05). The early dead chicks were higher in CLA1 and CLA2 than Control (18 and 32% compared with 9% for Control), and alive but not hatched chicks were 15 and 19% for CLA1 and CLA2, compared with 8% for Control (P<0.05). Maternal supplementation with CLA leads to a reduction in hatchability, liver TAG, and carcass total fat in newly hatched chicks.