Wk Of Experiment Research Articles

MicroRNAs Expression Induces Apoptosis of Macrophages in Response to Leishmania major (MRHO/IR/75/ER): An In-Vitro and In-Vivo Study.

Background:We aimed to investigate the effect of miR-15a mimic and inhibitor of miR-155 expression on apoptosis induction in macrophages infected with Iranian strain of Leishmania major in-vitro and in-vivo.Methods:RAW 264.7 cells were infected with L. major promastigotes (MRHO/IR/75/ER), and then were treated with miRNAs. For in-vivo experiment, BALB/c mice were inoculated with L. major promastigotes, and then they were treated with miRNAs. For evaluation of miRNA therapeutic effect, in-vitro and in-vivo studies were performed using quantitative Real-time PCR, Flow cytometry, lesion size measurement, and Limiting Dilution Assay (LDA). This study was performed in Shahid Beheshti University of Medical Sciences in 2019.Results:In-vitro results of flow cytometry showed that using miR-15a mimic, miR-155 inhibitor or both of them increased apoptosis of macrophages. In in-vivo, size of lesion increased during experiment in control groups (P<0.05) while application of both miR-155 inhibitor and miR-15a mimic inhibited the increase in the size of lesions within 6 wk of experiment (P=0.85). LDA results showed that microRNA therapy could significantly decrease parasite load in mimic or inhibitor receiving groups compared to the control group (P<0.05).Conclusion:miR-155 inhibitor and miR-15a mimic in L. major infected macrophages can induce apoptosis and reduce parasite burden. Therefore, miRNA-based therapy can be proposed as new treatment for cutaneous leishmaniasis.

Short communication: Relationships between physical form of oats in starter, rumen pH, and volatile fatty acids on hepatic expression of genes involved in metabolism and inflammation in dairy calves

In early-weaning programs, dietary effects on calf rumen development have been studied extensively, but very little information is available about the effects of a solid diet on hepatic metabolism in preweaned dairy calves. The objective of this experiment was to determine the effect of physical form of oats in calf starter on the expression of key hepatic gluconeogenic, β-oxidation, and acute phase protein genes in preweaned dairy calves. Samples were analyzed from 3 experiments that fed either ground or whole oats in calf starters. Briefly, 7 calves were slaughtered at 5 wk of age in experiment 1, 6 were slaughtered at 6 wk in experiment 2, and 7 were slaughtered at 7 wk in experiment 3, and liver tissue was collected for gene expression analysis. Calves from experiments 1 and 2 were cannulated, and their rumen pH and volatile fatty acids were measured during treatment periods. The mRNA expression of gluconeogenic enzymes pyruvate carboxylase (PC), cytosolic and mitochondrial phosphoenolpyruvate carboxykinase (PCK1 and PCK2), fatty acid oxidation enzyme carnitine palmitoyltransferase I (CPT1), and positive acute phase protein haptoglobin (HPT) was measured by real-time quantitative reverse-transcriptase PCR. Expression of HPT was greater in calves fed whole oats than in calves fed ground oats; however, PC, PCK1, PCK2, and CPT1 were not affected by the physical form of oats. All enzymes (PCK1, PCK2, HPT, and CPT1) except PC were affected by experiment; PCK1 and CPT1 had greater expression in experiment 2 than in experiments 1 and 3. Expression of PCK2 was similar in experiments 2 and 3 but greater than experiment 1. Expression of HPT was similar in experiments 1 and 2 but greater than experiment 3. The mRNA expression of enzymes PCK1, PCK2, and CPT1 differed between experiments 1 and 2 and was negatively correlated with rumen propionate and butyrate but had a positive relationship with rumen acetate. Similarly, rumen pH was different in experiments 1 and 2, averaging 5.69 in experiment 1 and 4.81 in experiment 2, and there was a negative correlation between mRNA expression of rate-limiting gluconeogenic PCK1, PCK2, and β-oxidation CPT1 enzymes and rumen pH of calves in experiments 1 and 2. We concluded that the physical form of oats in calf starter did not affect gene expression of gluconeogenic and β-oxidation enzymes in preweaned dairy calves. However, lower rumen pH may be related to the upregulation of these enzymes.

Excess calcium increases bone zinc concentration without affecting zinc absorption in rats

We examined zinc (Zn) metabolism in rats given diets containing excess calcium (Ca). Rats were given phytate-free diet containing 5 g Ca/kg (control), 12.5 g Ca/kg, or 25 g Ca/kg for 4 wk in Experiment 1. The dietary treatment did not affect Zn concentration in the plasma, testis, kidney, spleen and liver; however, Zn concentration in the femur and its cortex was significantly higher in rats given diet containing 25 g Ca/kg than in other rats. Rats were given phytate-free diet containing 5 g Ca /kg or 25 g Ca /kg for 4 wk in Experiment 2. After 12-h food deprivation, rats were given a diet extrinsically labeled by 67Zn with dysprosium as a fecal marker for 4 h. Feces were collected from 1 d before administration of the labeled diet to 5 d after administration. Excess Ca did not affect the true absorption of Zn and its endogenous excretion but increased femoral Zn. These results suggest that excess Ca improves Zn bioavailability without affecting Zn absorption when diets do not contain phytate.

Effects of nandrolone decanoate on VO2max, running economy, and endurance in rats.

The aim of the present study was to determine the effects of treatment with an anabolic androgenic steroid (AAS), nandrolone decanoate, on the submaximal running endurance (SRE), maximum oxygen consumption (VO2max), running economy (VO2submax), and blood oxygen carrying capacity of endurance trained rats. Forty male Wistar rats were randomly allocated into two groups: a sedentary group and an exercising group training on treadmill for 8 wk. Half of the trained and half of the sedentary rats received weekly either nandrolone decanoate (10 mg x kg(-1)) or placebo (Pl) for the last 6 wk of experiment. SRE and VO2max tests were performed several times for all four groups (N = 10 each).Red blood cells parameters were measured at the end of the experiment. The trained rats had increased their SRE compared with sedentary rats throughout the experiment. At the end of the trial, the trained rats receiving nandrolone decanoate ran 46% longer than trained rats receiving Pl during the SRE test (P < 0.05). At the end of the experiment, trained rats had greater maximal time to exhaustion and higher VO2max than those of the sedentary rats but there were no differences in VO2max, VO2submax, and red blood cells parameters between the trained rats receiving nandrolone decanoate and those receiving Pl. Nandrolone decanoate has no effect on the SRE, VO2max and VO2submax of untrained rats. AAS treatment combined with submaximal training enhances SRE more than training alone but exerts no additive effects on VO2max, running economy, and oxygen carrying capacity of blood. The results suggest that this improvement in SRE of trained rats is due to the impact of AAS on other factors involved in exercise adaptation.

Nickel deficiency diminishes sperm quantity and movement in rats.

Early studies on nickel essentiality with rats and goats indicated that nickel deprivation impaired reproductive performance. Nickel also has been found to influence cyclic nucleotide gated channels (CNG); these types of channels are important in sperm physiology. Thus, two experiments were conducted to test the hypothesis that nickel deficiency affects sperm physiology in a manner consistent with nickel having an essential function related to CNG channel functions. The experiments were factorially arranged with four treatment groups of eight weanling rats in each. In experiment 1, the treatments were supplemental dietary nickel of 0 and 1 mg/kg and N(omega)-nitro-L-arginine methyl ester (L-NAME, a nitric oxide synthase inhibitor) added to the drinking water (50 mg/100 mL) the last 3 wk of an 8-wk experiment. In experiment 2, the treatments were supplemental dietary nickel at 0 and 1 mg/kg and supplemental dietary sodium chloride (NaCl) at 0 and 80 g/kg. The NaCl and L-NAME variables were included to act as stressors affecting CNG channel activity. The basal diet contained per kilogram about 27 microg of nickel and 1 g of sodium. After 8 wk in experiment 1 and 16 wk in experiment 2, urine while fasting and testes and epididymis in both experiments, and seminal vesicles and prostates in experiment 2 were harvested for analysis. Nickel deprivation significantly decreased spermatozoa motility and density in the epididymides, epididymal transit time of spermatozoa, and testes sperm production rate. Nickel deficiency also significantly decreased the weights of the seminal vesicles and prostate glands. Excessive NaCl had no effect on sperm physiology; however, it decreased prostate gland weights. The findings support the hypothesis that nickel has an essential function that possibly could affect reproductive performance in higher animals, perhaps through affecting a CNG channel function.

Low-dose dexamethasone in the rat: a model to study insulin resistance.

The main aim of this study was to set up a new animal model to study insulin resistance. Wistar rats (6 or 7 per group) received the following for 4 wk in experiment 1: 1) vehicle, 2) 2 microg/day subcutaneous dexamethasone, 3) metformin (400 mg x kg(-1) x day(-1) os), and 4) dexamethasone plus metformin. In experiment 2 the rats received the following: 1) vehicle, 2) dexamethasone, 3) dexamethasone plus arginine (2%; as substrate of the nitric oxide synthase for nitric oxide production) in tap water, and 4) dexamethasone plus isosorbide dinitrate (70 mg/kg; as direct nitric oxide donor) in tap water. Insulin sensitivity was significantly reduced by dexamethasone already at week 1, before the increase in blood pressure (day 15) and without significant changes in body weight compared with vehicle. Dexamethasone-treated rats had significantly higher triglycerides, hematocrit, and insulin, whereas serum total nitrates/ nitrites were lower compared with vehicle. The concomitant treatment with metformin minimized all the described effects of dexamethasone. In experiment 2, only isosorbide dinitrate was able to prevent the observed dexamethasone-induced metabolic, hemodynamic, and insulin sensitivity changes. Chronic low-dose subcutaneous dexamethasone (2 microg/day) is a useful model to study the relationships between insulin resistance and blood pressure in the rat, and dexamethasone might decrease insulin sensitivity and increase blood pressure through an endothelium-mediated mechanism.

Influence of Dietary Phosphorus on Performance of Hy-Line W36 Hens

Two experiments were conducted to determine the effect of nonphytate phosphorus (NPP) on hen performance in an environmentally controlled house. In Experiment 1, 21-wk-old Hy-Line W36 hens (n = 1,248) were randomly assigned to 13 dietary treatments (0.1 to 0.7% NPP, at graded increments of 0.05%) for 17 wk. In Experiment 2, 45-wk-old Hy-Line W36 hens (n = 960) were randomly allocated to eight diets in a 2 × 4 factorial arrangement of treatments. Two levels of Ca (3 and 4%) and four levels of NPP (0.1, 0.2, 0.3, and 0.4%) were fed for 8 wk. Feed consumption (FC), egg production (EP), egg weight (EW), egg specific gravity (ESG), bone density (BD), bone mineral content (BMC), bone breaking strength (BBS), BW and mortality were evaluated to determine performance. Results of Experiment 1 indicated that FC, EP, and BW increased as NPP was increased from 0.1 to 0.7% (77 to 588 mg/hen/d). During Week 12, a sharp decrease in FC and EP was observed in hens fed the most deficient level of 0.1% NPP. Egg weight and ESG decreased linearly (P < 0.05) as dietary NPP was increased from 0.1 to 0.7%. However, after 14 wk, ESG decreased (P < 0.05) in hens fed 0.1% NPP. Bone breaking strength was higher (P < 0.05) in hens fed 0.3 to 0.4% NPP, indicating maximum bone quality. Mortality was higher (P < 0.05) in hens fed 0.01% NPP, followed by hens fed 0.15% NPP. In Experiment 2, a pronounced adverse effect of P deficiency was observed on FC and EP within 2 wk compared with 12 wk in Experiment 1. Reduction of NPP to 0.1% reduced BD, BMC, BBS and increased hen mortality (P < 0.05). Reducing dietary Ca from 4 to 3% decreased ESG (P < 0.05). A wide variation in response time to P deficiency indicated that P requirement varied for different performance criteria with age.

Effects of malnutrition during early lactation on development and feeding behavior under the self-selection paradigm

Selection of food can be affected by several factors, and with the method of self-selection, qualitative changes in nutritional balance may be detected. The goal of the present study was to evaluate feeding preferences in weaning rats using three macronutrients (protein, carbohydrate, and fat), through a free-choice method, evaluating the alteration in their feeding patterns as compared with the previous nutritional status during the early lactation period. We analyzed the effects of protein restriction during lactation over the nitrogen balance after the weaning. The dams were assigned to one of two diet conditions (nourished or malnourished). At weaning, two pups from each litter were housed individually in metabolic cages, and they were maintained on self-selection under a free-choice paradigm and were provided with separate sources of macronutrients. The parameter for evaluating the nutritional effectiveness of the diets was nitrogen balance. We observed that protein intake tended to increase and consumption of carbohydrate and fat tended to decrease progressively during the 3 wk of experiment. In selecting their own food, growing rats and malnourished rats consumed a larger amount of protein than the other rats. Nourished rats selecting their diet had a larger nitrogen balance than nourished rats receiving a composed diet; no nitrogen balance difference was found between the self-selecting groups. Rats can choose an adaptive form when recovering from protein malnutrition.

The effects of dietary available phosphorus levels and phytase on performance of young and older laying hens

In the first of two experiments (20 to 70 wk of age), eight treatments consisted of corn-soybean meal diets (0.34% total P, 3.8% Ca, 17% CP, 2,758 kcal ME/kg) containing 0.10, 0.15, 0.20, 0.25, or 0.45% available P (AP), with the three lowest AP diets supplemented with 300 units of phytase/kg of diet. A second experiment evaluated the effect of feeding the 0.10% AP diet with and without phytase on performance and time required for onset of P deficiency in older hens (70 to 76 wk of age). In Experiment 1, the 0.10% AP diet with no supplemental phytase depressed performance by 28 wk of age. No other significant differences in performance were observed among treatments for the entire 20- to 70-wk period except that the 0.15% AP diet with no phytase resulted in body weights and tibia ash that were lower (P < 0.05) than those of hens fed the 0.45% AP diet during the last 30 wk. The mean daily AP intake of hens fed the 0.10% AP, 0.15% AP, 0.45% AP, or 0.10% AP + phytase diets was 94,159, 499, or 108 mg, respectively. Excreta P concentration was decreased by approximately 50% in birds consuming 0.10% AP + 300 U/kg phytase compared with those consuming 0.45% AP. In the second experiment, P deficiency signs occurred within 3 wk of consuming the unsupplemented corn-soybean meal diet (0.10% AP) compared with 8 wk in Experiment 1. The results of this study indicate that phytase improves P utilization in corn-soybean meal diets for laying hens and that a corn-soybean meal diet containing 0.15% AP (159 mg AP/d) or containing 0.10% AP + 300 units of phytase/kg (108 mg AP/d) supported optimal egg production from 20 to 70 wk of age. Additionally, results suggested that older hens may exhibit P deficiency symptoms sooner than younger hens.

Liver α-Tocopherol Transfer Protein and Its mRNA Are Differentially Altered by Dietary Vitamin E Deficiency and Protein Insufficiency in Rats

To study how the expression of α-tocopherol transfer protein (α-TTP) and its mRNA are affected by protein and vitamin E status, Long-Evans male weanling rats were fed a vitamin E-deficient (DE), high vitamin E (HE, 5 g/kg diet of all-rac-α-tocopheryl acetate) or control (C) diet for 12 wk in Experiment 1; and fed a low-protein (LP) or control (C) diet for 6 wk in Experiment 2. The high and deficient vitamin E status of HE and DE groups in Experiment 1 were confirmed by changes in plasma pyruvate kinase activity as well as the concentrations of α-tocopherol in plasma and liver. As shown by the Northern and Western Blot Analysis, the expression of α-TTP in the liver of the DE group was significantly lower than, while that of the HE group was not different from, that of the controls. In contrast, the α-TTP mRNA levels did not differ among the C, DE and HE groups. α-Tocopherol in most peripheral tissues of rats fed the LP diet in Experiment 2 was significantly lower than that of the C. Both the α-TTP and its mRNA were significantly lower in the LP group than in the C. The results suggested that dietary vitamin E does not affect α-TTP gene expression except that the protein levels in the liver were lowered by vitamin E deficiency. On the other hand, protein inadequacy appeared to down-regulate the expression of the α-TTP gene.

Eimeria tenella Infection Induces Recrudescence of Previous Salmonella enteritidis Infection in Chickens

Four experiments were conducted to examine the effect of Eimeria tenella infection on the recrudescence of Salmonella enteritidis in previously infected chickens. Significant recrudescence of cecal colonization in the birds challenged with E. tenella was observed at 3 wk after S. enteritidis infection in Experiment 1, at 3 and 4 wk in Experiment 2, and at 3, 4, and 5 wk in Experiments 3 and 4. The recrudescence was indicated by .81 to 6.31 logs increase in cecal S. enteritidis counts and by higher percentages of ceca that were culture-positive. The possible prolonged cecal S. enteritidis shedding from chickens infected with coccidia into the environment might be important for the perpetuation of S. enteritidis infectious cycle. Except for Experiment 1, in which a significant higher culture-positive rate of the liver was detected in the coccidia-infected group, no significant difference of culture-positive rate of liver and spleen between the treatments was observed. The recrudescence of previous S. enteritidis infection caused by E. tenella infection was obviously related to the initial S. enteritidis dose size and time of exposure to coccidia.

Effects of Dietary Calcium and 1,25-Dihydroxycholecalciferol on the Development of Tibial Dyschondroplasia in Broilers During the Starter and Grower Periods

Two experiments were conducted to determine whether dietary 1,25-dihydroxycholecalciferol [1,25-(OH)2 D3] can prevent tibial dyschon-droplasia in broiler chickens throughout the growing period when withdrawn from the grower diet. The birds were reared in floor pens with pine shavings to 6 wk in Experiment 1 and 5 wk of age in Experiment 2. Calcium was fed at .65 or 1.00% and 1,25-(OH)2 D3 was fed at 0 or 5 μ g/kg to 3 wk of age. Half the birds consuming 1,25-(OH)2 D3 were then fed 0 μ g/kg until the end of the experiments. The higher level of calcium decreased the incidences of tibial dyschon-droplasia and severe lesions and increased bone ash. Dietary 1,25-(OH)2 D3 increased bone ash at both levels of calcium at 3 wk and the end of the experiments when supplemented for the duration of the studies. When 1,25-(OH)2 D3 was fed, tibial dyschondroplasia was reduced in Experiment 2 only at 3 wk. Tibial dyschondroplasia was decreased at 5 wk in Experiment 2 when .65% calcium was fed with or without 1,25-(OH)2 D3 from 3 to 5 wk of age. There were no treatment effects on plasma calcium, dialyzable phosphorus, or 25-hydroxycholecalciferol. Plasma 1,25-(OH)2 D3 was decreased at 3 and 5 wk in Experiment 2 when 1.00% calcium was fed. The results of Experiment 2 suggest that 1,25-(OH)2 D3 can prevent tibial dyschondroplasia caused by inadequate calcium when fed for only 3 wk. The bone ash observed when 1.00% dietary calcium is fed is equal to that obtained when 5 μg/kg l,25-(OH)2 D3 is fed with .65% calcium for the entire growout period.

Daily Energy Allotments and Performance of Broiler Breeders.: 1. Males

The effects of daily energy intake on reproductive performance of Arbor Acres males and on growth of their offspring was studied. In Experiment 1, 21 males were placed in individual pens with 12 females. Three rations, differing in energy, were fed from 24 to 57 wk of age with seven males receiving either 300, 340, or 380 kcal ME/d. In Experiment 2, 32 individually caged males were given daily allotments of 280, 320, 360, or 360 kcal ME/d from 26 to 32 wk of age and 300, 340, 380, or 380 kcal ME/d from 32 to 38 wk. Rations of the two groups of males fed the highest energy level differed in formulation, one being the same wheat shorts-based basal ration as fed to the two lower energy groups, only with additional fat, and the other being a corn-soybean-based ration. Body weight and testes weight were increased with increased energy allotment in both experiments but carcass composition was unaltered. There were no significant effects of energy intake on fertility or hatchability in either experiment. Even though mean differences were not significant, fertility in two pens dropped to near zero at 38 wk in Experiment 1. Semen characteristics and plasma testosterone concentrations were unaffected by energy intake in Experiment 2. There was a significant linear increase in 6-wk BW of broilers associated with the increase in sire energy intake in each of three batches of broilers grown in Experiment 1 and in one of two batches of broilers grown in Experiment 2.

Dietary Choline Requirement of Juvenile Hybrid Striped Bass

Two experiments were conducted to estimate the dietary choline requirement and to determine the effects of dietary choline on liver lipid deposition in juvenile hybrid striped bass (Monrone saxatilis x M. chrysops). Experimental diets contained 0.73 g total sulfur amino acids/100 g diet (0.47 g methionine + 0.26 g cyst(e)ine/100 g diet), thus meeting, but not exceeding, the requirement. Graded levels of choline bitartrate in Experiment 1 and choline chloride in Experiment 2 were added to the basal diet, resulting in eight dietary treatments in each experiment. Dietary treatments were 0, 250, 500, 1000, 2000, 4000, 6000 and 8000 mg choline/kg dry diet. Diets were fed for 12 and 10 wk in Experiments 1 and 2, respectively. Dietary choline concentrations significantly affected weight gain, feed efficiency, survival and total liver lipid concentrations in each experiment. Weight gain and feed efficiency were greatest in fish fed 500 mg choline/kg dry diet as choline bitartrate. Total liver lipid concentrations were variable but tended to be lowest in fish fed diets containing at least 2000 mg choline/kg diet. Survival was significantly lower in the group of fish fed 8000 mg choline/kg diet supplied by choline bitartrate. Weight gain and feed efficiency were greatest and total liver lipid concentration was lowest in groups of fish fed at least 500 mg choline/kg diet as choline chloride; survival was unaffected by dietary treatment. Therefore, choline chloride seems to be a better source of dietary choline than choline bitartrate and 500 mg choline/kg diet is adequate for maximum weight gain and prevention of increased liver lipid concentration in juvenile hybrid striped bass.

Pearl Millet in Diets of White Pekin Ducks

In two 21-d experiments, the performance, nutrient utilization, and carcass composition of ducks fed diets containing pearl millet were compared with those fed diets containing corn. Corn, in diets at two protein levels (22 vs 18% in Experiment 1 and 22 vs 16% in Experiment 2), was replaced by pearl millet either on an equal-weight or isonitrogenous basis. During the first 2 wk of the first experiment, corn diets compared on an isonitrogenous basis were superior (P < .05) to the millet diets in promoting weight gain (666 vs 633 g per duck) and feed consumption (965 vs 914 g per duck); but when compared on an equal-weight basis, the millet diets were similar to the corn diets in promoting growth. No significant differences were observed for weight gain, feed consumption, or feed efficiency at the end of 3 wk. Over the 21-d study, the higher protein diets were more efficiently (P < .05) converted to weight gain than the lower protein diets (.63 vs .60 g gain:g feed). Carcass protein in ducks fed the corn diets was greater (P < .05) than in those fed the pearl millet diets. In Experiment 2, growth performance differences across dietary protein levels were similar to those in Experiment 1. However in contrast to Experiment 1, feed consumption was similar for corn and pearl millet diets (776 vs 786 g per duck, respectively), and ducks fed the corn diets gained less (P < .05) than those fed the pearl millet diets (590 vs 622 g per duck) during the first 2 wk of Experiment 2. Results of the nutrient utilization trial conducted at the end of Experiment 2 revealed that diets containing pearl millet were higher (P < .05) in AME than those containing corn (3,300 vs 3,100 kcal/kg). These results indicate that pearl millet has a higher energy value and appears to be at least equal to corn in promoting weight gains in ducks.

Effects of In Ovo Hormone Administration at Day Eighteen of Embryogenesis on Posthatch Growth of Broilers

The effect of in ovo administration of hormones on broiler growth were investigated. In Experiment 1, fertile eggs were injected on day 18 of incubation with bovine growth hormone (pGH), porcine growth hormone (pGH), thyrotropin-releasing hormone (TRH), or vehicle. Hormone administration increased the body weights of males at 1 and 3 wk posthatch. In Experiment 2, fertile eggs were injected with pGH, TRH, or vehicle. A 27% protein diet was fed to 4 wk, and a 22% protein diet was fed from 4 to 8 wk. In Experiment 3, fertile eggs were injected with ovine growth hormone (oGH), TRH, or vehicle. The body weights of females increased at wk 6 following pGH treatments in Experiment 2 and at wk 4, 6 and 8 for oGH-treated birds fed a 22% protein diet from 0-8 wk in Experiment 3. Day 18 of in ovo administration of hormones did not persistently increase body weights except in oGH-treated females fed a 22% protein diet throughout the study.

Differential Age Response of Turkeys to Protein and Sorghum Tannin Levels

Three experiments were conducted to determine the effect of protein and dietary sorghum tannin levels on weight gain (WG), feed conversion (FC), and pancreas weight (PW) of female turkeys from Day 1 to 12 wk of age. Two protein levels (100 and 85% of NRC, 1984) and five tannin levels (0, .49, .98, 1.47, and 1.96%, expressed as percentage catechin equivalents) in a factorial arrangement of treatments were used in all experiments. Turkeys were fed the dietary treatments from Day 1 to 4 wk, 4 to 8 wk, and 8 to 12 wk in Experiments 1, 2, and 3, respectively. No significant (P > .05) interaction between protein and tannin level was observed for WG, FC, or PW in all experiments. Neither protein nor tannin level had an effect on PW expressed as a percentage of body weight. In all experiments, feeding the suboptimal protein level significantly (P < .05) depressed WG and FC of turkeys compared with the diet that was adequate in protein. Increasing tannin level linearly depressed WG and increased FC in Experiments 1 and 2. However, tannin level did not affect WG or FC of turkeys 8 to 12 wk of age (Experiment 3). It is possible that the presumably more fully developed digestive processes of 8-wk-old turkeys were able to overcome the antinutritional effects of tannins. Results of the present study suggest that if high tannin grains are to be utilized in turkey diets, they should be fed to birds older than 8 wk.

Effects of Lighting and Dietary Energy Source on Male Market Turkeys.: 1. Growth Performance Data

Two experiments were conducted with 528 and 500 Large White male turkeys to determine the effects of feeding either wheat or corn as the energy source and the effects of four different lighting treatments on growth, feed consumption, and feed conversion in a factorial arrangement. Wheat and corn diets were freely provided during the experiments and the lighting treatments began at 8 wk of age. The lighting treatments included: continuous light [C, 24 h light (L):0 h dark (D)], light decreasing 1 h/day per week until it reached 16L:8D (D1), light decreasing 2 h/day per week until it reached 16L:8D (D2), and intermittent light (I, 4L:2D). All birds were processed when the C birds were estimated to weigh 11.36 kg. No differences in body weight, feed consumption, or feed efficiency were found from 0 to 8 wk of age between turkeys fed diets with either wheat or corn as the energy source. For the period of 8 to 18 wk in Experiment 1 and 8 to 16 wk in Experiment 2, turkeys fed wheat diets were, respectively, .75 and 4.09% (P < .05) heavier than birds fed corn diets. Experiments 1 and 2 indicated decreased growth performance when decreasing day length treatments (Dl and D2) were used.

Beak Trimming Effects on Beak Length and Feed Usage for Growth and Egg Production ,

Two experiments were conducted to compare beak treatment effects on pullets of three genetic stocks. Within each stock, equal numbers were assigned to three treatments: no beak trimming (IN), beak trimming once (1X), and beak trimming twice (2X). Beak treatment, genetic stock, and age effects along with interactions among main effects were examined for production-associated traits during rearing and brief periods of early egg production.Beaks of 1X and 2X pullets remained shorter than those of IN pullets through final measurements at 36 and 32 wk of age in Experiments 1 and 2, respectively. However, differences in beak length decreased as age increased. Upper beaks of 2X pullets remained shorter than those of 1X pullets, but lower beaks of 1X and 2X pullets did not differ by 20 wk in Experiment 2.Weight gains, feed usage, and efficiency of growth were affected by beak treatments. Beak trimming reduced gains, feed eaten, feed wasted, and total feed used, and 2X pullets used their feed more efficiently for weight gain and egg production. A general decrease occurred in differences among beak treatments for weight gains, feed eaten, feed wasted, and efficiency of gains with increasing age during rearing. Nevertheless, significant differences in feed consumed, feed wasted, and efficiency of feed used for egg production indicated an economic advantage in favor of beak trimming.

Influence of Increasing Photoperiod and Toe Clipping on Breast Buttons of Turkeys

Two 17-wk experiments compared the effects of an increasing photoperiod treatment (INC) versus a constant photoperiod treatment (23H), and intact toes versus clipped toes, on the breast button incidence and performance of heavy torn turkeys. Under INC, the photoperiod was increased gradually from 8 to 23 h between 4 and 16 wk. Under 23H, the photoperiod remained constant at 23 h. Use of INC versus 23H resulted in a significant reduction in breast button incidence at 17 wk in both experiments (P < .05). Toe clipping had no effect on breast button incidence. The presence of breast buttons was positively correlated with body weight at 12 wk, and area of unfeathered skin over the keel at 17 wk. In Experiment 1, the photoperiod treatments had no significant effect on 17-wk body weight or mortality, but the INC treatment had an adverse effect on feed efficiency (P < .05). In Experiment 2, turkeys reared under INC were heavier at 17 wk (P < .05), with similar feed efficiencies. Mortality was significantly lower on INC than 23H up to 12 wk in Experiment 2 (P < .05). Turkeys with intact toes were .44 kg heavier than turkeys with clipped toes at 17 wk in both experiments (P < .05) and had similar feed efficiencies. Mortality to 4 wk was lower for turkeys with intact than clipped toes in Experiment 2 (P < .05). Increasing photoperiod treatments have potential for improving turkey performance, survival, and carcass quality. The adverse impact of toe clipping on growth and early survival stresses the need for alternatives to toe clipping for prevention of downgrading due to scratches.