M. Jing

Effect of feeding hemp seed and hemp seed oil on laying hen performance and egg yolk fatty acid content: Evidence of their safety and efficacy for laying hen diets

Forty-eight 19-wk-old Bovan White laying hens were fed 1 of 5 diets containing either hemp seed (HS) or hemp seed oil (HO). The level of HO was 4, 8, or 12%, whereas the level was 10 or 20% for the HS. A set of 8 birds fed wheat-, barley-, and corn oil-based diets served as the control. Performance was monitored over 12 wk. Average hen-day egg production was not affected upon feeding of either HS or HO diets. Egg weight was higher than that of the controls for hens consuming the 20% HS diet (P < 0.05). Feed intake was lower than that of the controls for birds consuming the 4% HO diet but similar across other treatments. Final BW were not affected by diet, with the exception of being lower than that of the controls (P < 0.05) in hens consuming the 12% HO diet. The total egg yolk n-3 fatty acid content increased linearly (P < 0.05) with increasing dietary α-linolenic acid provision with the HS- or HO-based diets. A quadratic response (P < 0.05) was observed for docosahexaenoic acid levels in egg yolk in response to increasing dietary α-linolenic acid supply. The expression of hepatic fatty acid desaturase 1 and 2, key genes for the desaturation of long-chain polyunsaturated fatty acids, was significantly decreased (50-60% of controls; P < 0.05) as a result of feeding HS or HO diets. Based on the results from the current study, the inclusion of the hemp products HS or HO in the diets of laying hens up to a maximum level of 20 and 12%, respectively, does not adversely effect the performance of laying hens and leads to the enrichment of the n-3 fatty acid content of eggs.

Molecular cloning and tissue distribution of reduced folate carrier and effect of dietary folate supplementation on the expression of reduced folate carrier in laying hens

The reduced folate carrier (RFC) has been postulated to be a major entity for folate transport activity in humans and other mammals. However, there are limited reports of the importance of RFC in an avian system. In the current study, therefore, the molecular cloning and tissue distribution of RFC, as well as the effect of dietary folate supplementation on the expression of this transporter, were investigated in the chicken. Shaver White laying hens (n=8 per diet) received 3 wheat-based diets containing the following: 1) no supplemental folate, 2) folic acid (10.00 mg/kg), or 3) 5-methyltetrahydrofolate (11.30 mg/kg) for 21 d. The mRNA expression levels were analyzed by quantitative real-time PCR. The results showed that the cloned partial RFC cDNA containing the full coding region from duodenum was 99% homologous to the reference gene available in GenBank. A broad expression profile of RFC transcripts was observed, with RFC mRNA detected in the brain, liver, kidney, spleen, lung, intestine, ovary, and testis, as well as other tissues. Real-time PCR analysis revealed that no significant differences (P>0.05) due to diet were found in the mRNA levels of RFC in the duodenum and cecum. However, compared with the basal diet, jejunal mRNA levels of RFC were decreased (P<0.05) in hens fed with the 5-methyltetrahydrofolate diet, but the reduction did not reach significance (P=0.077) in the hens fed the folic acid diet. Overall, the current study demonstrated that the RFC cDNA containing the full coding region was successfully cloned from the duodenum of laying hens. The wide tissue distribution of RFC transcripts is suggestive of an important role of RFC in the process of folate transport in the chicken. Moreover, dietary folate supplementation could downregulate the jejunal mRNA expression of RFC. Such findings will lay the foundation of future work involving the RFC in avian systems, including laying hens.

Dietary and ontogenic regulation of fatty acid desaturase and elongase expression in broiler chickens

Effects of diet and ontogeny on the expression of fatty acid desaturases and elongases were examined in broiler chickens. In Study 1, 120 day-old male chicks received one of six diets with LA:ALA ranging from 46:4 to 16:34, for 33 days. Total n-6 PUFA decreased, and n-3 PUFA increased in response to a decrease in the dietary LA:ALA. FADS1, FADS2, ELOVL2 and ELOVL5 mRNAs were highest (P<0.05) in birds fed lower LA:ALA diets. In Study 2, 60 day-old male chicks were fed a basal diet, and liver samples were collected on day of hatch, and on days 2, 7, 14, 21 and 35 post-hatch. Total n-6 and n-3 PUFA increased (P<0.01) from days 7 to days 21. FADS1, FADS2 and ELOVL2 mRNAs generally increased (P<0.01) with age. These findings provide evidence for the dietary and developmental regulation of PUFA metabolism in broiler chickens.

Performance, serum biochemical responses, and gene expression of intestinal folate transporters of young and older laying hens in response to dietary folic acid supplementation and challenge with Escherichia coli lipopolysaccharide

The present study was conducted to investigate the effects of dietary folic acid (FA) supplementation on performance, serum biochemical indices, and mRNA abundance of intestinal folate transporters in young and older laying hens after acute lipopolysaccharide (LPS) challenge. Two experiments were conducted separately involving 48 Shaver White young laying hens (24 wk of age) in experiment 1 and 48 Shaver White older laying hens (58 wk of age) in experiment 2. Birds were fed 2 diets in a complete randomized design. The diets were wheat-soybean meal based, with or without supplemental 4 mg of FA/kg of diet. Birds were fed for 8 wk, during which time feed consumption and egg production were monitored. At the end of each feeding experiment, 6 hens from each dietary treatment were injected intravenously with 8 mg/kg of BW of either Escherichia coli LPS or sterile saline. Four hours after injection, blood and intestinal samples were collected for further analysis. Compared with the control, dietary FA supplementation increased egg weight and egg mass and decreased serum glucose levels in the young laying hens, and reduced serum uric acid in the older laying hens (P < 0.05). Relative to saline injection, plasma homocysteine, serum calcium, and phosphorus levels were found to be lower in both young and older laying hens after LPS challenge (P < 0.05). Other serum biochemical variables and the mRNA expression of 2 folate transport genes in the small and large intestine were differentially affected by LPS challenge, and some of those responses varied with the age of the birds. Additionally, interactions between diet and LPS challenge were specifically found in the older laying hens. In summary, in addition to improving production performance, there were effects of dietary FA supplementation and its interaction with LPS challenge on biochemical constituents, and age played a role in the development of responses to diet and bacterial LPS infections.

Effects of zinc deficiency and zinc supplementation on homocysteine levels and related enzyme expression in rats

Methionine synthase (MS) and betaine-homocysteine methyltransferase (BHMT) are both zinc (Zn)-dependent methyltransferases and involved in the methylation of homocysteine. The objective of this study was to investigate the effects of dietary Zn supply on homocysteine levels and expression of the two enzymes in growing rats. Male weanling Sprague-Dawley rats were assigned randomly to four dietary groups (n=8/group) for 3 weeks: Zn deficient (ZD; <1mg Zn/kg); Zn control (ZC; 30mg Zn/kg); Zn supplemented (ZS; 300mg Zn/kg); pair fed (PF; 30mg Zn/kg) to the ZD group. Serum and femur Zn concentrations were 83% and 58% lower in ZD, and 49% and 62% higher in ZS compared to ZC (P<0.001), respectively. The ZD rats had lower feed intake (37%), body weight gains (45%), liver (43%) and kidney (31%) weights than those of ZC (P<0.001), but these parameters in ZD were not significantly different from the PF controls. Serum homocysteine concentrations were 65% higher in ZD compared to PF (P<0.05), and there was no significant difference in serum folate levels between ZD and PF groups. The mRNA expression of liver and kidney MS was 57% and 38% lower in ZD than PF (P<0.001), respectively. Hepatic and renal BHMT mRNA levels were not altered in ZD compared to controls. The aforementioned measurements were not significantly different between ZS and ZC groups, except Zn levels. These results demonstrated that homocysteine homeostasis appeared to be disturbed by Zn deficiency but not Zn supplementation, and elevated serum homocysteine might be due to reduced expression of MS during Zn deficiency.

Characterization of folate-dependent enzymes and indices of folate status in laying hens supplemented with folic acid or 5-methyltetrahydrofolate

The conversion of folic acid (FA) to the biologically active 5-methyltetrahydrofolate (5-MTHF) is necessary for the deposition of folate in the egg. A study was conducted to compare egg folate concentrations, indices of folate status, and activities of folate-dependent enzymes in response to equimolar intake of either FA or 5-MTHF in laying hens. Forty-eight laying hens, 24 wk of age, from 2 different strains (Shaver White and Shaver Brown) were randomly assigned to receive 1 of 3 (n = 8 per strain) dietary treatments: 1) basal diet with no supplemental folate, 2) basal diet + 10 mg/kg of FA, or 3) basal diet + 11.3 mg/kg of 5-MTHF for 3 wk. A completely randomized design with 3 dietary treatments and 2 laying hen strains in a 3 x 2 factorial arrangement was used. Data were subjected to ANOVA, using the PROC GLM procedure of SAS. Plasma homocysteine, serum, and egg folate concentrations; hepatic serine hydroxymethyltransferase; and methionine synthase activity were affected by dietary folate supplementation but not by its form (FA and 5-MTHF). Relative to control hens, plasma homocysteine was decreased (P < 0.05) by 14.2%, whereas serum and egg folate were increased (P < 0.05) by 78.3 and 61.8%, respectively, in hens consuming either folate compound. Hepatic serine hydroxymethyltransferase and methionine synthase activity were increased and decreased (P < 0.05), respectively, in folate-fed birds compared with control-fed birds. Hepatic dihydrofolate reductase was influenced by both the addition and form of dietary folate, being higher (P < 0.05) in FA-fed birds than in 5-MTHF and control-fed birds. Feed efficiency was improved (P < 0.05) in 5-MTHF-fed birds relative to FA-fed birds. Strain of hen influenced serum folate and plasma homocysteine concentrations but not other indices of folate metabolism. Overall, FA and 5-MTHF have equivalent effects in enhancing egg folate concentrations and improving folate status in laying hens. Also, supplementation and form of folate may modulate the activity of folate-dependent enzymes.

Response of older laying hens to an Escherichia coli lipopolysaccharide challenge when fed diets with or without supplemental folic acid

Folic acid plays a key role in nucleic acids and protein synthesis, and has been associated with anti-inflammatory effects in LPS-induced infections. To this end, a study was conducted to investigate the effects of dietary folic acid (FA) supplementation in older laying hens (58 to 66 wk of age) challenged with Escherichia coli lipopolysaccharide (LPS). A total of 24 Shaver White laying hens at 58 wk were fed 2 diets. The diets were wheat-soybean-based, with either 0 or 4 mg of supplemental FA per kg of diet. After 8 wk of feeding and at 66 wk, the hens were injected intravenously with 8 mg of LPS or saline per kg of BW. Four hours after injection, blood was collected and hens were euthanized to obtain spleen and cecal tonsils. The T cell subsets in the blood and the spleen (CD4+ and CD8+), total IgG, and biochemical constituents (total protein, albumin, globulin, and fibrinogen) were not influenced (P > 0.05) by dietary FA supplementation. However, LPS injection decreased (P < 0.05) biochemical constituents, CD4+, and CD8+ cells in the blood, whereas CD4+:CD8+ ratio and total IgG increased (P < 0.05), and fibrinogen was not influenced. Gene expression in the spleen and cecal tonsils was not influenced by dietary FA supplementation except a diet × challenge interaction for interleukin (IL)-8 in the spleen; IL-8 decreased in FA-fed hens that were treated with LPS. Also, FA supplementation decreased the expression of IL-8 in cecal tonsils. Relative to saline-injected hens, expression of IL-1β, interferon-γ, and IL-10 increased in the LPS-injected hens in the spleen and cecal tonsils, IL-8 increased in LPS-injected hens only in the cecal tonsils, whereas Toll-like receptor 4, IL-4, IL-17, and IL-18 increased in the LPS-injected hens only in the spleen; however, LPS decreased expression of IL-13 in the cecal tonsils. In conclusion, FA did not affect inflammatory responses in older laying hens; more studies are required to investigate possible protective effects of FA in laying hens.

Proton-coupled folate transporter (PCFT): molecular cloning, tissue expression patterns and the effects of dietary folate supplementation on mRNA expression in laying hens.

1. The aim was to investigate the molecular characterisation and effects of dietary folate supplementation on mRNA concentrations of the proton-coupled folate transporter (PCFT) in chicken. 2. Twenty-four (n = 8/treatment) laying hens were allocated at random to one of three dietary treatments: a basal diet without supplemental folate, or the same diet with either 10·00 mg/kg folic acid or 11·30 (equimolar) mg/kg 5-methyltetrahydrofolate (5-MTHF) for 21 d. The PCFT cDNA was cloned using the TA cloning system, and mRNA concentrations were determined by real-time polymerase chain reaction (PCR). 3. The PCFT cDNA (1643 bp) was cloned from the duodenum and its transcripts were widely distributed in chicken tissues. Duodenal and caecal PCFT mRNA was not affected by dietary treatments; however, jejunal PCFT mRNA was significantly reduced in hens fed the 5-MTHF diet versus the basal diet. 4. A broad tissue distribution of PCFT transcripts is indicative of a vital role of PCFT in the folate transport in chicken. The expression of jejunal PCFT mRNA was down-regulated by dietary 5-MTHF supplementation. These findings contribute to an understanding of the development of folate transport and the PCFT system in avian systems involving laying hens.

Performance and tissue fatty acid profile of broiler chickens and laying hens fed hemp oil and HempOmegaTM

&NA; This study was conducted to determine the effects of hemp oil (HO) and HempOmega (H&OHgr;), an equivalent product to HO, on performance and tissue fatty acid profile of layers and broiler chickens in two separate experiments. In the first experiment, forty 19‐wk old Lohmann white laying hens were randomized to 1 of 5 dietary treatments, either a control diet or a control diet supplemented with 4 or 8% hemp oil provided by HO or H&OHgr;, for a period of 6 wk (n = 8/diet). In experiment 2, 150‐day‐old mixed‐sex (75 male; 75 female) Ross 308 chicks were randomly allocated into 5 dietary treatments, a control diet or a control diet supplemented with either 3 or 6% hemp oil provided by HO or H&OHgr;, each with six replicates of 5 chicks for a 21‐d feeding period. Performance of layers and broilers was not affected by dietary treatments. Animals provided with either HO or H&OHgr; diets had greater total n‐3 polyunsaturated fatty acids (PUFAs), alpha‐linolenic acid (ALA), eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA) in egg yolks, thighs, and breasts compared to the control diet (P < 0.01), and monounsaturated fatty acids (MUFAs) content of egg yolks and thighs decreased (P < 0.05). The levels of total n‐6 PUFAs, linoleic acid (LA), or arachidonic acid (ARA) of the egg yolk and meat were generally not affected by dietary supplementation with HO or H&OHgr;, but gamma‐linolenic acid (GLA) was notably increased (P < 0.01). The current data show that inclusion of hemp oil up to 8% in layer diets and 6% in broiler diets provided by HO or H&OHgr; does not negatively affect overall performance of birds and results in the enrichment of n‐3 PUFAs and GLA in eggs and meat.

Assessment of the minimal available phosphorus needs of pullets during the pre-laying period

Abstract Dietary phosphorus (P) oversupply is costly to the poultry industry and represents a point source of excessive P discharge to the environment via manure application to soils. The current study was conducted to investigate the effects of dietary available P (AP) level on growth performance, plasma biochemistry, bone characteristics, and P flow in order to assess minimal AP needs of pullets during the pre‐lay period. A total of 192 Lohmann pullet chicks were randomly allocated to one of 4 treatments with 8 replicate cages of 6 birds per cage. The pullets of Low (L; the lowest AP regimen) were fed diets in a sequence of 0.200, 0.175, and 0.150% AP for the age period of 0 to 4 wk, 4 to 8 wk, and 8 to 16 wk, respectively. The AP level was increased by an increment of 0.1% in each phase in Low‐Medium (LM), Medium‐High (MH) and High (H), thus making H (control) consisting of 0.500, 0.475, and 0.450% AP. Overall, there were no main effects of treatment on body weight gain (BWG), feed intake (FI) and feed conversion ratio (FCR). However, compared with the H treatment, BWG or FI of the L treatment was lower during the first 8 wk post‐hatch, but became comparable or higher over the last 8 wk (P < 0.05); FCR of L birds was greater over wk 0 to 4 but became smaller over wk 8 to 16 (P < 0.05). Plasma P was lower in L than H treatments at wk 8 but turned comparable at wk 16 (P < 0.001). Bone characteristics were not different for pullets fed various AP regimens. Total P intake and excretion were reduced with lowering dietary AP (P < 0.001), but its retention percent was not affected. The results indicated that the lowest AP regimen (0.200‐0.175‐0.150%) in the current study was adequate to support healthy growth and development of pre‐lay pullets, while reducing P excretion in manure.