Productive performance of broiler chicks fed diets containing irradiated meat-bone meal

Experiments were carried out to study the changes in the values of feed efficiency (FE), total protein efficiency (TPE) and metabolizable energy efficiency (MEE) of broiler chicks fed during four age periods (14–21, 21–28, 28–35 and 35–42 days). Five experimental diets were similar in composition but different in the irradiation dose (0, 5, 10, 25 or 50 kGy) applied to the meat–bone meal content of each diet. The results indicated that feeding of broiler chicks on irradiated meat–bone meal (5–50 kGy) had no significant (P>0.05) effects on FE, TPE, MEE and body weight gain during the four experimental age periods. The average values of the FE (feed consumption/weight gain), TPE (weight gain/total protein consumption) and MEE (metabolizable energy consumption in MJ/kg gain) were 1.96, 2.59 and 23.13, respectively. The values of FE and MEE increased while TPE decreased significantly (P<0.05) with age. The pooled FE value was 1.60 during the 14–21 days of age and increased to 2.66 from 35–42 days of age. However, the TPE value was 3.01 during the 14–21-day age period and decreased to 1.82 over the 35–42-day age period. The energy consumption value to produce one kg of body weight increased during the 35–42-day period by 7.71–12.72 MJ/kg gain in comparison with that from the other experimental age periods. Weight gain rate decreased significantly (P<0.05) during the 35–42-day period (66 g/week/bird) when compared with the rate observed during the 14 through 35-day age period.     

Effects of dietary chromium and zinc on egg production, egg quality, and some blood metabolites of laying hens reared under low ambient temperature

This experiment was conducted to evaluate the effects of chromium (chromium picolinate, CrPic) and zinc (ZnSO₄·H₂O) on egg production, egg quality, and serum insulin, corticosterone, glucose, cholesterol, and total protein concentrations of laying hens reared under a low ambient temperature (6.8°C). One hundred twenty laying hens (Hy-Line; 32 wk old) were divided into 4 groups, 30 hens per group. The laying hens were fed the control diet (T1) or the control diet supplemented with either 400 μg of Cr/kg of diet (T2), 30 mg of Zn/kg of diet (T3), or 400 μg of Cr plus 30 mg of Zn/kg of diet (T4). Although the dry matter intake (DMI) was similar (p>0.05) for all treatment groups, supplemental chromium and zinc either individually or together increased live-weight change, egg production, and improved feed efficiency (p<0.05). However, no significant differences were observed between T4 and T2 or T3. Compared to T1, supplemental chromium and zinc increased egg weight, eggshell weight, eggshell thickness, egg specific gravity, and Haugh unit (p<0.05) in T2, T3, and T4 groups, among which there was no significant difference. Serum insulin concentration increased (p<0.05) and corticosterone concentration decreased (p<0.05) with dietary chromium and zinc supplementation. Serum glucose and cholesterol concentrations decreased (p<0.05) and protein concentrations increased (p<0.001) with dietary chromium and zinc supplementation in all treatment groups. The results of this study indicated that either supplemental dietary chromium or zinc increased plasma insulin and decreased corticosterone concentrations and that had a positive effect on performance of laying hens under low ambient temperature.     

海藻粉和抗菌肽对肉鸡生长性能、免疫器官指数和肠道菌群的影响

为探讨海藻粉和抗菌肽不同添加水平对肉鸡生长性能、免疫器官指数和肠道菌群的影响。选取1日龄体重相近的AA肉鸡504羽,随机分为7个处理,每处理6个重复,每重复12羽。对照组饲喂基础日粮,试验组在基础日粮中添加不同水平(1.0%、3.0%、5.0%)的海藻粉和抗菌肽(300 mg/kg、600 mg/kg)。试验分前期(1~21 d)和后期(22~42 d)共42 d。结果表明:(1)添加不同水平的海藻粉对前期、后期和全期肉鸡的料重比有显著影响(P0.05);对21日龄肉鸡的脾脏指数和胸腺指数及对42日龄肉鸡的法氏囊指数差异显著(P0.05);降低了21日龄和42日龄肉鸡盲肠大肠杆菌的数量(P0.05),增加了盲肠乳酸菌的数量(P0.05)。(2)添加不同水平的抗菌肽对后期和全期肉鸡的料重比有显著差异(P0.05);对21日龄肉鸡的脾脏指数和胸腺指数及对42日龄肉鸡的法氏囊指数差异显著(P0.05);降低了21日龄和42日龄肉鸡盲肠大肠杆菌的数量(P0.05),增加了盲肠乳酸菌的数量(P0.05)。(3)海藻粉和抗菌肽交互作用对前期、后期和全期肉鸡的料重比有明显影响(P0.05);对21日龄肉鸡的脾脏指数和胸腺指数及对42日龄肉鸡的法氏囊指数差异显著(P0.05);降低了21日龄和42日龄肉鸡盲肠大肠杆菌的数量(P0.05),增加了盲肠乳酸菌的数量(P0.05)。本研究得出以下结论,海藻粉和抗菌肽能促进肉鸡生长,提高肉鸡免疫器官指数和改善肠道菌群,且二者间存在协同效应,添加5%的海藻粉和300 mg/kg抗菌肽综合效果最佳。     

Effects of dietary supplementation of keratinase on growth performance, nitrogen retention and intestinal morphology of broiler chickens fed diets with soybean and cottonseed meals

A preparation of keratinase (KE, 400,000 enzyme units/g) was evaluated as a feed additive for its effects on growth performance, nutrient digestibility and intestinal development in broiler chickens. Four experimental diets were arranged as a 2 × 2 factorial with two sources of protein, either soybean meal (SBM) alone or a combination of SBM and cottonseed meal (1:1 on crude protein basis) and with or without 1.0 g KE/kg diet. Dietary supplementation of KE increased body weight gain from 1 to 21 days of age and improved feed conversion ratio from 1 to 42 days of age. Also, KE supplementation enhanced nitrogen retention (P<0.001) and starch digestibility (P<0.001), reflecting the high level of KE and some amylase activities in the enzyme preparation. Microscopic examination of the small intestine on day 21 indicated that KE increased the ratio of villus height to crypt depth (P<0.05). The results suggest that KE has positive effects on growth performance, dietary component digestibility and intestinal development of broilers.     

Effect of superovulation on maternal serum progesterone concentration, uterine and fetal weights at weeks 7 and 15 of pregnancy in Javanese Thin-Tail ewes

Twenty-one pregnant ewe lambs (nine superovulated and 12 non-superovulated) were used to study the effects of superovulation (injecting 700 IU PMSG at the end of diestrus) on maternal serum progesterone concentrations, uterine and fetal weights at weeks 7 and 15 of pregnancy. In the ewes sacrificed at week 7 of pregnancy, superovulation increased the mean number of corpora lutea (P<0.01), fetuses (P<0.01), maternal mean serum progesterone concentration (P<0.01), mean uterine weight (P<0.05), total fetal weight (P<0.01), and average fetal weight (P<0.01) by 133%, 69%, 354%, 66%, 150% and 40%, respectively, when compared to non-superovulated ewes. In the ewes sacrificed at week 15 of pregnancy, superovulation increased the number of corpora lutea (P<0.01), fetuses (P<0.05), maternal serum progesterone concentration (P<0.01), uterine weight (P<0.05), total fetal weight (P>0.05), and average fetal weight (P<0.05) by 207%, 20%, 84%, 37%, 29% and 24%, respectively, compared to those non-superovulated ewes. It was concluded that the increased number of corpora lutea and, therefore, their hormonal secretions by superovulation could increase uterine and fetal growth and development.     

Effect of Dietary Supplementation of Organic Chromium on Performance, Carcass Traits, Oxidative Parameters, and Immune Responses in Commercial Broiler Chickens

An experiment was conducted to study effect of supplementing graded concentrations (0, 100, 200, 300, or 400 μg/kg diet) of organic chromium (Cr) on performance, carcass traits, oxidative stress, and immune responses in commercial broiler chickens reared in open-sided poultry house under tropical climatic conditions. Each diet was fed ad libitum to eight replicates consisting of six birds in each pen from 1 to 42 days of age. Body mass gain and feed efficiency at 21 and 42 days of age and relative mass of liver, abdominal fat, and ready to cook yields at 42 days of age were not affected (P > 0.05) by supplementing organic Cr in broiler diet. Body mass loss during pre-slaughter holding period (12 h) reduced and relative breast mass increased nonlinearly (P < 0.01) with concentration of Cr in diet. Lipid peroxidation decreased, while activities of glutathione peroxidase and glutathione reductase in plasma increased nonlinearly with Cr supplementation. The ratio between heterophyl and lymphocyte was not affected (P > 0.05) with Cr supplementation in broiler diet. Relative mass of lymphoid organs (bursa, spleen, and thymus) and antibody production to Newcastle disease vaccination were not affected (P > 0.05) by the treatments employed. The cell-mediated immunity (lymphocyte proliferation ratio) increased nonlinearly with dietary Cr concentration. The results of the present study indicated that supplementation of organic Cr did not influence body mass and feed efficiency. However, supplementation of the Cr reduced pre-slaughter holding losses, increased the relative mass of breast, and increased antioxidant status and lymphocyte proliferation in broilers reared in tropics.     

Effect of dietary supplementation of Ligustrum lucidum on performance,egg quality and blood biochemical parameters of Hy-Line Brown hens during the late laying period

The fruit of Ligustrum lucidum (FLL, Nuzhenzi in Chinese) is an important traditional medicine, and have attracted significant research attention because of their various biological activities. However, there are few research reports available on the use of FLL as a feed additive in livestock nutrition, particularly in layers. This study was conducted to determine the effects of supplementation of the diet of laying hens with FLL on laying performance, egg quality and blood metabolites. A total of 360 72-week-old hens were allocated to three dietary treatments (eight replications of 15 hens/treatment group) and were fed either a control diet or a diet supplemented with an inclusion level of 0.25% or 0.50% of FLL powder in the final feed, until 78 weeks of age. Hens were housed in a three-tier cage system. Feed and water were provided ad libitum. Blood samples and eggs were collected at the end of the experiment. The results showed that dietary supplementation with FLL did not affect egg weight, feed conversion ratio, eggshell thickness, albumen height, egg yolk color, eggshell breaking strength or egg shape index. However, FLL supplementation significantly decreased (P<0.001) mortality, cracked-egg rate and blood serum levels of cholesterol, low-density lipoprotein cholesterol, triglycerides and alanine aminotransferase, and increased (P<0.001) blood serum levels of high-density lipoprotein cholesterol. No differences in serum levels of total protein, albumin, glucose, calcium, aspartate aminotransferase or alkaline phosphatase were observed in hens fed FLL compared with the control group. It can be concluded that FLL, at a supplementation level of 0.25% final feed, can be used as an effective feed additive to improve the performance of laying hens during the late laying period.     

Palm kernel meal as a feed for poultry. 4. Use of palm kernel meal by laying birds

In each of 2 experiments, 200 laying birds of the Harco strain were used to determine the effects of increasing amounts of dietary palm kernel meal (PKM) on egg production rate and egg quality. The results show that up to 40% of PKM can be included in diets for layers without any adverse effects on performance or egg quality. As the proportion of PKM increased beyond 40%, there was a significant drop in egg production (P < 0.05), egg weight (P < 0.01), feed intake (P < 0.01) and feed conversion efficiency (P < 0.01). The cost of feed required to produce 1 kg of eggs was reduced by feeding with PKM. Diets containing 50–70% of PKM caused the production of very watery faeces. It is recommended that the maximum level of inclusion of PKM in the diet of laying birds should be 40%.     

The effect of site of starch digestion on performance of broiler chickens

A growth trial with 420 broiler chickens (35 per experimental unit) was conducted in order to evaluate whether bird performance (Days 0–38) is affected by site of starch digestion. Two diets were formulated with the same calculated apparent metabolisable energy, digestible lysine, and digestible starch content. The diets contained starch sources with known amounts of rapidly digestible starch (RDS, starch digested until the posterior jejunum) and slowly digestible starch (SDS, starch digested in the ileum). Diets were either high (H) or low (L) in SDS content. RDS and SDS contents were 298 and 52 g/kg for the H diet and 345 and 7 g/kg for the L diet, respectively. Starch in the H diet was supplied by waxy maize, peas and sorghum and starch in the L diet was supplied by tapioca and common maize. Birds receiving the H diet consumed more feed (P<0.10), grew faster (P<0.01) and had a lower feed conversion ratio (P<0.01) than birds receiving the L diet. The results suggest that broiler chickens perform better on diets containing a minimal amount of slowly digestible starch. Future experiments are necessary to investigate the relation between amount of slowly digestible starch and performance of broiler chickens.     

Whole inedible date in the grower-finisher broiler diets and the impact on productive performance, nutrient digestibility and meat quality

The growth performance, carcass characteristics and meat quality measurements were evaluated on broiler chicks fed different dietary levels of whole inedible dates (WID). WID used in this study were consisted of date fruits (～850 g/kg) and date pits (～150 g/kg). Three hundred unsexed Lohman broiler chicks were randomly and equally distributed into six groups. Each was formed of 50 chicks (five replicates, 10 chicks per replicate), and was assigned to a dietary treatment. Six dietary treatments of WID (0, 30, 60, 90, 120 and 150 g/kg feed) were included in the formation of isocaloric (metabolizable energy of ～3060 kcal/kg feed) and isonitrogenous (CP of ～192 g/kg feed) broiler rations. The treated rations were fed to the group chicks between 15 and 42 days of age (the experimental period). A straight-run design was considered. At 42 days of age, five males from each treatment were randomly chosen and slaughtered to determine carcass characteristics, internal organs and meat quality measurements. Digestibility of nutrients was measured at the end of the experimental period using five caged-individual males per treatment. The inclusion of broiler rations on WID for up to 150 g/kg feed, over the experimental period, did not significantly influence body weight gain (1452 to 1521 g/chick), feed intake (3268 to 3621 g/chick), feed conversion ratio (2.26 to 2.36 kg/kg) and dressed carcass (63.4% to 67.3%). In addition, levels of WID for up to 150 g/kg feed did not significantly influence the digestibility of nutrients and meat quality measurements. Such results suggest the possible inclusion of broiler rations on WID for up to 150 g/kg feed, during the period of 15 to 42 days of age without adverse effects on growth performance and meat quality.     

Effects of time and dietary iron on tissue iron concentration as an estimate of relative bioavailability of supplemental iron sources for ruminants

Two experiments were conducted to investigate the effects of time and dietary Fe on tissue Fe concentrations following short-term, high level supplementation for use as a bioassay procedure for supplemental Fe sources for ruminants. In Experiment 1, 28 wethers were allotted randomly to four experimental diets which were fed for 15 or 30 days. The basal maize–soyabean meal–cottonseed hulls diet (193 mg kg⁻¹ Fe) was supplemented with 0, 400, 800 or1200 mg kg⁻¹ added Fe from reagent grade ferrous sulfate (FeSO₄·7H₂O). Iron concentrations in liver, kidney, and spleen increased (P<0.05) as dietary Fe increased; however, muscle, heart, and bone Fe concentrations were unaffected. A logarithmic transformation of liver or kidney Fe concentrations at 30 days regressed on added dietary Fe produced the best fits to a linear model. In Experiment 2, bioavailability of Fe from three feed grade ferrous carbonates known to differ (carbonates A, B, and C) was compared to that from reagent grade ferrous sulfate. The dietary treatments fed for 30 days included the above basal diet (90 mg kg⁻¹ Fe) supplemented with 0, 300, 600 or 900 mg kg⁻¹ added Fe from ferrous sulfate or 600 mg kg⁻¹ Fe from ferrous carbonates A, B, or C. Liver Fe concentrations from sheep fed ferrous sulfate were numerically greater than those of animals fed the carbonate sources or control diet. Kidney Fe concentrations from lambs fed ferrous sulfate at 600 mg kg⁻¹ Fe or carbonate-A were greater (P<0.05) than those fed carbonates B or C. Iron concentrations in spleen were lower (P<0.05) in lambs fed carbonate-B than for those fed 600 mg kg⁻¹ Fe as ferrous sulfate, but were similar to other carbonates. Overall average bioavailability estimates based on multiple regression slope ratios for the three tissues were ferrous sulfate 1.00, carbonate-A 0.55, carbonate-B 0.00, and carbonate-C 0.20. Estimates for carbonates A and C were similar to those based on hemoglobin concentrations reported previously for young swine supplemented at dietary concentrations near the requirement.     

The Influence of Naringin or Hesperidin Dietary Supplementation on Broiler Meat Quality and Oxidative Stability

An experiment was conducted to examine the effects of supplementing broiler feed with hesperidin or naringin, on growth performance, carcass characteristics, breast meat quality and the oxidative stability of breast and thigh meat. Two hundred and forty 1-day-old Ross 308 broiler chickens were randomly assigned to 6 groups. One of the groups served as a control (C) and was given commercial basal diets, whereas the other five groups were given the same diets further supplemented with naringin at 0.75 g/kg (N1), naringin at 1.5 g/kg (N2), hesperidin at 0.75 g/kg (E1), hesperidin at 1.5 g/kg (E2) and a-tocopheryl acetate at 0.2 g/kg (E). At 42 days of age, 10 chickens per treatment group were slaughtered for meat quality and oxidative stability assessment. No significant differences were observed among groups in final body weight, carcass weight and internal organs weights (P>0.05) apart from liver that decreased linearly with increased levels of naringin (P-linear<0.05). Regarding the breast meat quality parameters, only redness (a*) value was higher in E1 and N1 group compared to VE group (P<0.05), while all the others i.e. shear values (N/mm²), pH₂₄, cooking loss (%) and L* and b* color parameters were not significantly different among groups (P>0.05). Measurement of lipid oxidation values showed that after hesperidin and naringin dietary supplementation, malondialdehyde values decreased in tissue samples in a dose depended manner (P-linear<0.05). In conclusion, hesperidin and naringin, positively influence meat antioxidative properties without negative implications on growth performance and meat quality characteristics in poultry, thus appearing as important additives for both the consumer and the industry.     

Optimal dietary concentration of chromium for alleviating the effect of heat stress on growth,carcass qualities,and some serum metabolites of broiler chickens

This study was conducted to determine the effects of chromium (chromium picolinate, CrPic) supplementation at various levels (0, 200, 400, 800, or 1200 microg/kg of diet) on performance, carcass characteristics, and some serum metabolites of broiler chickens (Ross) reared under heat stress (32.8 degrees C). One hundred fifty old male broilers were randomly assigned to 5 treatment groups, 3 replicates of 10 birds each. The birds were fed either a control diet or the control diet supplemented with either 200, 400, 800, or 1200 microg Cr/kg of diet. Increased supplemental chromium resulted in an increase in body weight (p = 0.01, linear), feed intake (p < or = 0.05, linear), and carcass characteristics (p < or = 0.05, linear) and improved feed efficiency (p = 0.01, linear). Increased supplemental chromium decreased serum corticosterone concentration (p = 0.01, linear), whereas it increased serum insulin and T3 and T4 concentrations (p = 0.01). Serum glucose and cholesterol concentrations decreased (p = 0.01), whereas protein concentrations increased linearly (p = 0.001) with higher dietary chromium supplementation. Results of the present study conclude that a supplementation of diet with chromium at 1200 ppb can alleviate the detrimental effects of heat stress in broiler.     

Effects of β-glucanase supplementation of barley diets on growth performance of broilers

A trial was performed to examine the effects of levels of barley substitution and supplementation with β-glucanase in a corn-soybean diet on growth performance and intestinal characteristics of broiler chickens. The experiment involved five levels of barley substituted for corn (0, 125, 250, 500, and 1000 g/kg) and two levels of β-glucanase supplement (with 0.5 g/kg and without) in a factorial arrangement with two replicates. Four hundred day-old commercial strain Harber broiler chickens were randomly allocated into twenty groups of ten dietary treatments for a six-week feeding trial, growing (0-3 week) and finishing period (4-6 week). Unless supplemented with β-glucanase, broilers receiving the diet with more than 250 g/kg of the barley substitute gained slower during the growth period. Conversely, supplementing β-glucanase did not improve total weight gain (0-6 weeks) with a diet of 500 g/kg barley substitution. As the level of barley substitution increased, feed intake in the growing period decreased significantly and viscosity of the intestinal contents increased. However, such an increase did not significantly influence feed conversion (P > 0.05). Supplementation with β-glucanase on diet up to 250 g/kg of barley substitute not only enhanced body weight gains of growing broilers, but also improved the live-weight of six-week-old broilers (P < 0.05).     

The impacts of fermented feed on laying performance,egg quality,immune function,intestinal morphology and microbiota of laying hens in the late laying cycle

Fermented feed has the potential to improve poultry gastrointestinal microecological environment, health condition and production performance. Thus, the present study was undertaken to explore the effects of fermented feed on the laying performance, egg quality, immune function, intestinal morphology and microbiota of laying hens in the late laying cycle. A total of 360 healthy Hy-Line Brown laying hens aged 80 weeks were used to conduct a 56-day study. All hens were randomly separated into two treatment groups, with five replicates of 36 hens each as follows: basal diet containing 0.0% fermented feed (CON) and 20% fermented feed (FF). Subsequent analyses revealed that fermented feed supplementation was associated with significant increases in laying rates together with reduced broken egg rates and feed conversion ratio for hens in FF group (P < 0.05). There were additionally significant increases in both albumen height and Haugh unit values in hens following fermented feed supplementation (P < 0.05). Fermented feed was also associated with increases in duodenal, jejunal and ileac villus height (P < 0.05). Laying hens fed fermented feed had higher immune globulin (Ig)A, IgG, IgM levels (P < 0.01,) and higher interleukin 2, interleukin 6, tumour necrosis factor α and interferon γ (P < 0.05) concentrations than CON. Analysis of the microbiota in these laying hens revealed the alpha diversity was not significantly affected by fermented feed supplementation. Firmicutes abundance was reduced in caecal samples from FF hens relative to those from CON hens (30.61 vs 35.12%, P < 0.05). At the genus level, fermented feed was associated with improvements in relative Lactobacillus, Megasphaera and Peptococcus abundance and decreased Campylobacter abundance in laying hens. These results suggest that fermented feed supplementation may be beneficial to the laying performance, egg quality, immunological function, intestinal villus growth and caecal microecological environment of laying hens at the end of the laying cycle.     

Effects of l-carnitine and niacin supplied by drinking water on fattening performance,carcass quality and plasma l-carnitine concentration of broiler chicks

The present study was initiated to determine whether dietary supplemental L-carnitine and niacin affect growth performance, carcass yield, abdominal fat and plasma L-carnitine concentration of broiler chicks. One-day-old broiler chicks (COB500) were used in the experiment. A two by two factorial arrangement was employed with two levels (0 and 50 mg/l) of supplemental L-carnitine and two levels (0 or 50 mg/l) of supplemental niacin in drinking water as main effects. Body weight gain was significantly improved by L-carnitine, or L-carnitine + niacin supplementation during the first 3 weeks. However, supplemental L-carnitine and niacin did not change body weight gain during the last 3 weeks of the experimental period. Supplemental L-carnitine significantly improved feed intake during the first 3 weeks. Supplemental L-carnitine or niacin did not influence carcass weight, carcass yield and abdominal fat weight. L-carnitine content in the plasma was significantly higher in the groups receiving supplemental L-carnitine and L-carnitine + niacin. It is concluded that dietary supplemental L-carnitine or L-carnitine + niacin could have positive effects on body weight gain and feed intake during the early stages of growing. However, supplemental L-carnitine or L-carnitine + niacin were not of benefit regarding the complete growth period.     

Evaluation of Florina (Pelagonia) sheep breed for growth and carcass traits

Two experiments were conducted to evaluate the performance of growing Florina (Pelagonia) lambs fed a high concentrate diet, as well as the effect of slaughter weight on carcass characteristics. The assessment of the growth used 12 male and 12 female individually penned weaned lambs until they reached 60% of their mature body weight (BW), while assessment of the effect of slaughter weight at weaning (42 days of age), and at 30%, 45% and 60% of the mature BW, on carcass characteristics used 40 male and 40 female weaned lambs. In experiment 1, results showed that Florina lambs have good growth. Male lambs grew faster (P < 0.001) than female lambs, resulting in a lower (P < 0.001) feed conversion ratio (FCR) for males. Rate of gain, feed consumption and FCR increased (P < 0.001) as the experiment progressed. In experiment 2, results showed that degree of maturity affected (P < 0.001) fasted body weight and carcass weight, as well as all carcass characteristics and commercial cuts, except the steaks cut which did not differ. Florina lambs can be slaughtered in heavier carcass weights, heavier than the 15 kg as the present practice. The heavier carcasses can appeal to wider range of consumers due to the excellent muscle development and the reduced visible fat cover. Florina sheep raised for heavy carcass meat production may be more economically beneficial for the breeders and the increased meat produced locally can help reduce need for importing meat from abroad.     

Effect of Dietary Vitamin A on Reproductive Performance and Immune Response of Broiler Breeders

The effects of dietary vitamin A supplementation on reproductive performance, liver function, fat-soluble vitamin retention, and immune response were studied in laying broiler breeders. In the first phase of the experiment, 1,120 Ross-308 broiler breeder hens were fed a diet of corn and soybean meal supplemented with 5,000 to 35,000 IU/kg vitamin A (retinyl acetate) for 20 weeks. In the second phase, 384 Ross-308 broiler breeder hens were fed the same diet supplemented with 5,000 to 135,000 IU/kg vitamin A (retinyl acetate) for 24 weeks. The hens'' reproductive performance, the concentrations of vitamins A and E in liver and egg yolk, liver function, mRNA expression of vitamin D receptor in duodenal mucosa, antibody titers against Newcastle disease virus vaccine, and T-cell proliferation responses were evaluated. Supplementation of vitamin A at levels up to and including 35,000 IU/kg did not affect reproductive performance and quadratically affected antibody titer to Newcastle disease virus vaccine (p<0.05). Dietary addition of vitamin A linearly increased vitamin A concentration in liver and yolk and linearly decreased α-, γ-, and total tocopherol concentration in yolk (p<0.01) and α-tocopherol in liver (p<0.05). Supplementation of vitamin A at doses of 45,000 IU/kg and above significantly decreased egg weight, yolk color, eggshell thickness and strength, and reproductive performance. Dietary vitamin A significantly increased mRNA expression of vitamin D receptor in duodenal mucosa (p<0.05), increased aspartate amino transferase activity, and decreased total bilirubin concentration in serum. Supplementation of vitamin A at 135,000 IU/kg decreased the proliferation of peripheral blood lymphocytes (p<0.05). Therefore, the maximum tolerable dose of vitamin A for broiler breeders appears to be 35,000 IU/kg, as excessive supplementation has been shown to impair liver function, reproductive performance, and immune response.     

The influence of dietary vitamin E, fat, and methionine on blood cholesterol profile, homocysteine levels, and oxidizability of low density lipoprotein in the gerbil

A 90-day feeding study with gerbils was conducted to evaluate the influence of dietary vitamin E levels (25 mg/kg diet, 75 mg/kg, 300 mg/kg, and 900 mg/kg), two levels of dietary methionione (casein or casein+L-methionine (1% w/w)) and two sources of lipid (soybean oil [20%] or soybean oil [4%]+coconut oil [16%, 1:4 w/w]) upon serum lipids (total cholesterol, HDL-cholesterol, LDL-cholesterol). In addition, this study examined the effects of diet-induced hyperhomocysteinemia and supplemental dietary vitamin E on the oxidation of low density lipoproteins. Tissue vitamin E (heart, liver, and plasma) demonstrated a dose response (P≤0.001) following the supplementation with increasing dietary vitamin E (25, 75, 300, and 900 mg/kg). In addition, tissue vitamin E levels were found to be higher (P≤0.001) in those animals receiving a combination of coconut oil+soybean oil as compared to the group receiving soybean oil solely. Blood cholesterol profiles indicated an increase (P≤0.001) in total cholesterol and LDL cholesterol by the influence of saturated fat and supplemental methionine. Low-density lipoprotein cholesterol profile demonstrated a reduction (P≤0.001) at the higher dietary vitamin E levels (300 and 900 mg/kg) as compared to the 25 mg/kg and 75 mg/kg dietary vitamin E. Plasma protein carbonyls were not influenced by dietary vitamin E nor by supplemental methionine intake. In vitro oxidation of LDL showed that vitamin E delayed the lag time of the oxidation phase (P≤0.001) and reduced total diene production (P≤0.001). On the contrary, supplemental methionine decreased (P≤0.001) the delay time of the lag phase, whereas total diene production was increased (P≤0.001). Plasma lipid hydroperoxides were significantly reduced (P≤0.05) with supplemental dietary vitamin E, whereas supplemental L-methionine (1%) resulted in a significant (P≤0.05) increase in lipid plasma hydroperoxide formation. Plasma homocysteine was elevated (P≤0.001) with supplemental dietary L-methionine (1%) as well as the inclusion of dietary saturated fat. The present data showed that 1) a combination of dietary lipids (saturated and unsaturated fatty acids) as well as vitamin E and methionine supplementation altered blood cholesterol lipoprotein profiles; 2) in vitro oxidation parameters including LDL (lag time and diene production) and plasma hydroperoxide formations were affected by vitamin E and methionine supplementation; and 3) plasma homocysteine concentrations were influenced by supplemental methionine and the inclusion of dietary saturated fat.