Effects of sulfur amino acid supplementation on broiler chickens exposed to acute and chronic cyclic heat stress.

Chronic heat stress can result in oxidative damage from increased reactive oxygen species. One proposed method to alleviate the chronic effects of HS is the supplementation of sulfur amino acids (SAA) which can be metabolized to glutathione, an important antioxidant. Therefore, the objective of this experiment was to determine the effects of dietary SAA content on broiler chickens exposed to HS from 28 to 35 d on broiler performance, body temperature, intestinal permeability, and oxidative status. Four experimental treatments were arranged as a 2 × 2 factorial consisting of HS (6 h at 33.3°C followed by 18 h at 27.8°C from 28 to 35 d of age) and Thermoneutral (TN- 22.2°C continuously from 28 to 35 d) and 2 dietary concentrations of SAA formulated at 100% (0.95, 0.87, and 0.80% for starter, grower, and finisher diets) or 130% SAA (1.24, 1.13, and 1.04% for starter, grower, and finisher diets). A total of 648-day-old, male Ross 708 chicks were placed in 36 pens with 18 chicks/pen and 9 replicates per treatment. Data were analyzed as a 2 × 2 factorial in JMP 14 (P ≤ 0.05). No interaction effects were observed on broiler live performance (P > 0.05). As expected, HS reduced BWG by 92 g and increased FCR by 11 points from 28 to 35 d of age compared to TN, respectively (P ≤ 0.05). The supplementation of SAA had no effect on live performance (P > 0.05). Cloacal temperatures were increased by 1.7, 1.4, and 1.2°C with HS at 28, 31, and 35 d compared to TN, respectively (P ≤ 0.05) and dietary SAA did not alter cloacal temperatures. At 28 d of age, supplementation of SAA to birds exposed to HS interacted as serum FITC-dextran (an indicator of intestinal permeability) was reduced to that of the TN group (P ≤ 0.05). The interaction was lost at 31 d, but HS still increased intestinal permeability (P ≤ 0.05). By 35 d, broilers were able to adapt to the HS conditions and intestinal permeability was unaffected (P > 0.05). Potential oxidative damage was reduced by increased SAA supplementation as indicated by an improvement in the reduced glutathione to oxidized glutathione ratio of 5 and 45 % at 28 (P = 0.08) and 35 d (P ≤ 0.05). These data suggest that intestinal permeability is compromised initially and to at least three d of heat exposure before the bird can adjust. However, oxidative damage in the liver of broilers exposed to HS is more chronic, building over the entire 7 d HS period and increased dietary SAA might have some protective effects on both broiler intestinal permeability and oxidative stress responses to HS.

Effects of a direct fed microbial (DFM) on broiler chickens exposed to acute and chronic cyclic heat stress in two consecutive experiments.

Two consecutive 35 d experiments were conducted to investigate the effects of a multistrain DFM fed continuously to broiler chickens exposed to HS from 28 to 35 d on broiler performance, body composition, ileal digestibility, and intestinal permeability using serum Fluorescein Isothiocyanate Dextran (FITC-d) concentration. The treatments were arranged as a 2 × 2 factorial with temperature: Elevated (HS: 33 ± 2°C for 6 h and 27.7°C for the remaining 18 h from 28 to 35 days of age) and Thermoneutral (TN: 22 to 24°C over the entire 24-h day from 28 to 35 days of age) and diet: corn-soybean meal based with and without DFM (3-strain Bacillus; Enviva PRO) fed over the entire 35-d period as the two factors. Experimental diets were formulated to meet all nutrient recommendations based on breed standards using a starter (0-10 d), grower (10-21 d), and finisher (21-35 d) period. For each of the 2 experiments, 648 Ross 708 broiler chicks were allotted among the treatments with 9 replicate pens of 18 broilers. Data were analyzed as a 2 × 2 factorial within each experiment in JMP 14. In both experiments, cloacal temperatures were increased (P ≤ 0.05) in the broilers subjected to the HS treatment at both 28 d (acute) and 35 d (chronic). Supplementing birds with DFM reduced cloacal temperatures in the Experiment 1 at 28 d, but not at the other time periods. The HS treatment reduced body weight gain and lean tissue accretion from 0 to 35 d in both experiments (P ≤ 0.05). In Experiment 2, when the litter was reused BWG was increased by 36 g/bird with supplementation of DFM (P ≤ 0.05). Ileal digestibility at 28 d (2 h post HS) was improved with DFM supplementation in both experiments (P ≤ 0.05). Serum FITC-d increased with HS at both 28 and 35 d. Serum FITC-d was generally decreased with DFM at 28 d but the response was inconsistent at 35 d. Overall, the results suggest that HS reduced broiler performance and DFM treatment improved intestinal permeability and nutrient digestibility responses to HS in both experiments but did not improve performance until built up litter was used in Experiment 2.

Effects of available phosphorus source and concentration on performance and expression of sodium phosphate type IIb cotransporter, vitamin D-1α-hydroxylase, and vitamin D-24-hydroxylase mRNA in broiler chicks.

This experiment was conducted to examine the effect of 2 phosphorus (P) sources on broiler performance to day 14. The P bioavailability was estimated using bird performance and tibia ash measurements, whereas P digestibility, intestinal P transporter, kidney vitamin D-1α-hydroxylase, and vitamin D-24-hydroxylase mRNA abundances were also determined. Slope regression analysis was used to determine the bioavailability of dicalcium phosphate (Dical P) and nanocalcium phosphate (Nano P) with dietary available P (AvP) set to 0.20% P (control) using AvP from the major ingredients and Dical P. The experimental treatments were achieved by supplementation with either Dical P or Nano P to generate 0.24, 0.28, 0.32, and 0.36% AvP. A total of 648-day-old unsexed broiler chicks were divided into 72 birds per treatment (8 replicate cages of 9 birds). Slope regression analysis showed positive linear relationships between BW, feed intake (FI), tibia ash weight (TAW), and tibia ash percentage (TAP) with dietary Dical P and Nano P levels. Comparisons between regression slopes for Dical P and Nano P fed birds were not significantly different for BW, feed intake, tibia ash weight, and tibia ash percentage, indicating similar P bioavailability from Dical P and Nano P. There were interactions between P source and AvP for feed efficiency (FE) and apparent ileal P digestibility (AIPD). Dicalcium phosphate had greater FE than Nano P at 0.28% AvP and greater AIPD than Nano P at 0.24% AvP. The addition of AvP from Dical P and Nano P resulted in reduced sodium phosphate cotransporter mRNA abundance in the duodenum in a dose-dependent response. In the kidney, vitamin D-1α-hydroxylase mRNA abundance was greater at 0.36% Nano P compared with control, but there was no difference with Dical P. There was no difference in vitamin D-24-hydroxylase mRNA abundance between control and supplementation with Nano P or Dical P. In conclusion, Nano P and Dical P had the same bioavailability but had different effects on gene expression.

Effect of high concentrations of dietary vitamin D3 on pullet and laying hen performance, skeleton health, eggshell quality, and yolk vitamin D3 content when fed to W36 laying hens from day of hatch until 68 wk of age.

The objective of this experiment was to investigate the effects of various dietary concentrations of vitamin D3 (D3) on pullet and laying hen performance, eggshell quality, bone health, and yolk D3 content from day of hatch until 68 wk of age. Initially, 440 Hy-line W36-day-old chicks were randomly assigned to 5 dietary treatments: 1,681 (control); 8,348; 18,348; 35,014; 68,348 IU D3/kg. At 17 wk of age, pullets were assigned to experimental diets with 12 replicate groups of 6 birds. At 17 wk of age, pullets fed diets containing 8,348 and 35,014 IU D3/kg had an increased bone mineral density in comparison to the control fed birds (P ≤ 0.01). Body weights of pullets fed the diet with 68,348 IU D3/kg were lower than other treatments (P ≤ 0.01). Hen-housed egg production (HHEP) of hens fed the 35,014 IU D3/kg diet was increased in comparison to control-fed hens (P ≤ 0.01), whereas HHEP of those fed 68,348 IU D3/kg diet was reduced in comparison to all other treatments (P ≤ 0.01). Shell breaking strength of eggs from hens fed 8,348, 35,014 and 68,348 IU D3/kg was increased in comparison to eggs from control-fed birds (P ≤ 0.01). Fat-free tibia ash content of hens fed any of the diets supplemented with D3 (8,348 to 68,348 IU D3/kg) was increased in comparison to control-fed hens (P ≤ 0.05). Yolk D3 content increased linearly with dietary D3 and the D3 transfer efficiency for the control, 8,348 IU, 18,348 IU, 35,014 IU, and 68,348 IU D3 treatments were 8.24, 10.29, 11.27, 12.42, and 12.06%, respectively. These data suggest that supplementation of dietary D3 up to 35,014 IU D3/kg feed maintained if not increased laying hen performance and enhanced pullet and laying hen skeletal quality as well as yolk D3 content and eggshell quality. Feeding pullets at a higher level 68,348 IU of D3 resulted in reduced growth and ultimately decreased performance of laying hens.

The impact of ß-glucans on performance and response of broiler chickens during a coccidiosis challenge.

Coccidiosis is a costly parasitic disease to the poultry industry with multiple prevention methods being explored to control its impact. This study evaluated the feeding effects of ß-glucans on performance and responses of chickens during a coccidiosis challenge. Cobb 500 male broilers (n = 1280) were assigned to 1 of 8 treatment groups (8 replicate pens; 20 birds/pen) in a 2 × 4 factorial arrangement, including non-infected and Eimeria-infected birds fed for 28 d a control diet, control + BG (150 g/MT Algamune 50), control + BGZn (100 g/MT Algamune 50 Zn), and control + 0.01% Salinomycin (Sal). On d15, birds in the challenge groups received a mixed Eimeria inoculum. Birds and feed were weighed weekly on a per pen basis to evaluate body weight gain (BWG), feed intake (FI), and feed conversion ratios (FCR). Lesion scores were assessed 6 d post infection (d21) on 3 birds per pen. Performance data were subjected to ANOVA and differences were established using the LS-MEANS statement with significance reported at P ≤ 0.05. There were minor differences in lesion scores among the dietary treatments in the infected groups with reduced duodenal and cecal scores in the Sal group compared to the BGZn and BG groups, respectively. The coccidiosis challenge main effect resulted in a significant reduction in 0-28 d BW and FI. Dietary treatment resulted in non-significant effect on BWG, but Sal addition resulted in increased FI. A significant diet X challenge interaction resulted in higher FCR in the Eimeria-challenged birds supplemented with Sal and BGZn in comparison to the other challenged groups, likely due to reduced mortality in the challenged Sal and BGZn groups. Body composition analysis at d28 revealed that the Eimeria challenge reduced both fat and lean tissue contents, where the ß-glucans and Sal birds had lower fat percent than control birds.

Comparative omega-3 fatty acid enrichment of egg yolks from first-cycle laying hens fed flaxseed oil or ground flaxseed.

When laying hen diets are enriched with omega-3 polyunsaturated fatty acids to generate value-added eggs for human consumption markets, concentrations of alpha-linolenic (ALA), eicosapentaenoic (EPA), and docosahexaenoic acids (DHA) in the yolk can reach 250 mg/50 g whole egg. Flaxseed, a rich source of ALA, is commonly used for omega-3 enrichment; however, the impact of dietary flaxseed source (extracted oil vs. milled seed) on fatty acid transfer to egg yolk in laying hens is unknown. Therefore, transfer of ALA, EPA, and DHA into egg yolk from extracted flaxseed oil or milled flaxseed was evaluated in Hy-Line W-36 laying hens over an 8-week feeding period (25 to 33 wk old). Hens (n = 132) were randomly housed with 3 birds/cage (4 replicates/treatment) for each of the 11 treatment groups. Diets were isocaloric and consisted of a control diet, 5 flaxseed oil diets (0.5, 1.0, 2.0, 3.0, or 5.0% flaxseed oil), and 5 milled flaxseed diets (calculated flaxseed oil concentration from milled flaxseed 0.5, 1.0, 2.0, 3.0, 5.0%). Increasing dietary concentrations of flaxseed oil and milled flaxseed resulted in increased ALA, EPA, and DHA concentration in egg yolk, and fatty acid deposition from flaxseed oil was 2 times greater compared to milled flaxseed when fed at the same dietary inclusions (P < 0.01). Egg yolk EPA and DHA concentrations were not different due to oil or milled source (P = 0.21); however, increasing dietary inclusion rates of flaxseed oil from either source increased yolk EPA and DHA (P < 0.01). Hens fed either flaxseed oil or milled flaxseed resulted in reduced BW change as dietary concentrations increased (P = 0.02). Feed efficiency increased as flaxseed oil increased in concentration, while feeding milled flaxseed decreased feed efficiency (P = 0.01). Analysis of the nitrogen corrected apparent metabolizable energy of flaxseed oil resulted in 7,488 kcal/kg on an as-fed basis. Dietary flaxseed oil improved feed efficiency and increased ALA deposition into yolk compared to a milled source, demonstrating flaxseed oil to be a viable alternative for ALA egg enrichment.

Effects of peroxidized corn oil on performance, AMEn, and abdominal fat pad weight in broiler chicks.

There is a trend to use more alternative lipids in poultry diets, either through animal-vegetable blends, distillers corn oil, or yellow grease. This has resulted in the use of lipids in poultry diets with a higher concentration of unsaturated fatty acids, which have a greater potential for peroxidation. The objective of this experiment was to determine the effects of peroxidized corn oil on broiler performance, dietary AMEn, and abdominal fat pad weight. The same refined corn oil sample was divided into 3 subsamples, 2 of which were exposed to different peroxidative processes. The 3 diets contained the unperoxidized corn oil (UO), a slowly peroxidized corn oil (SO; heated for 72 h at 95°C with compressed air flow rate of 12 L/min), or a rapidly peroxidized corn oil (RO; heated for 12 h at 185°C with compressed air flow rate of 12 L/min). Diets were fed from 0 to 14 d of age with each lipid fed at a 5% inclusion rate, continuing on from 15 to 27 d of age with each lipid fed at a 10% inclusion rate. There were 6 Ross 708 broiler chicks per cage with 10 replicates for each of the 3 dietary treatments. Abdominal fat pad and excreta collection was performed on d 27. Body weight gain, feed intake and feed efficiency were measured for the 0 to 14 and 0 to 27 d periods. The increased level of peroxidation reduced AMEn in broiler diets (UO = 3,490 kcal/kg; SO = 3,402 kcal/kg; RO = 3,344 kcal/kg on an as-is basis; SEM = 12.9, P ≤ 0.01). No significant treatment differences were observed among oil supplemented birds for BW gain, feed intake, feed efficiency, or abdominal fat pad weight. In conclusion, corn oil peroxidation status resulted in a decrease in dietary AMEn, but had minimal effects on broiler performance or fat pad weights.

Effects of long-term supplementation of laying hens with high concentrations of cholecalciferol on performance and egg quality.

There is current interest in increasing human vitamin D dietary intake without having to modify human eating habits. One method to increase human dietary vitamin D intake is to generate eggs with increased concentrations of vitamin D through high-concentration vitamin D feeding in the diets of laying hens. Although eggs can be produced with high concentrations of vitamin D, the consequences of these diets on hen performance and egg quality have not been validated. The objective of this research is to quantify the effects of high concentrations of cholecalciferol (D3) on laying hen performance and egg quality. Hy-Line W36 laying hens were placed on 1 of 5 experimental diets for 40 wk: 1) control (contained 2,200 IU of D3/kg of diet), 2) control + 7,500 IU of D3/kg of diet (9,700 IU of D3/kg of diet total), 3) control + 15,000 IU of D3/kg of diet (17,200 IU of D3/kg of diet total), 4) control + 22,500 IU of D3/kg of diet (24,700 IU of D3/kg of diet total), and 5) control + 100,000 IU of D3/kg of diet (102,200 IU of D3/kg of diet total). Egg production and hen mortality were monitored daily. Feed intake was determined weekly. Eggs were collected at predetermined points throughout the 40-wk period (19 to 58 wk of bird age) for assessment of egg weight, egg component weights, Haugh unit, yolk color score, specific gravity, egg mass, and feed efficiency. There were no consistent differences among the dietary treatments over the experimental period. Hens supplemented with up to 102,200 IU of D3/kg of diet resulted in no significant reductions in egg production, feed intake, feed efficiency, egg component weights, yolk color, Haugh units, and specific gravity in comparison with the control-fed hens (P > 0.05). These data suggest the addition of cholecalciferol to the diet of the laying hen at concentrations up to 102,200 IU of D3/kg of diet had no consistent negative effects on laying hen performance or egg quality.

Tolerance for excess basic zinc chloride and basic copper chloride in chicks.

(1) Four chick experiments were conducted to determine toxicity estimates for basic zinc chloride (BZC) and basic copper chloride (BCC), now being used as sources for these minerals. (2) In experiment 1, New Hampshire x Columbian crossbred chicks were fed 0, 500, 1000, 1500, 3000 and 5000 mg Zn/kg from BZC (Zn5Cl2(OH)8). Broken-line regression analysis showed that the minimal toxic break points for chick weight gain and gain:food were 1720 and 2115 mg Zn/kg, respectively. (3) Crossbred chicks were fed 0, 150, 250, 500, 750 and 1000 mg Cu/kg from BCC (Cu2(OH)3C) in experiment 2. Regression analysis indicated that the minimal toxic break points for chick weight gain and gain:food were 642 and 781 mg Cu/kg, respectively. (4) In experiment 3, commercial broiler chicks were fed 0, 1500, 2000 and 2500 mg supplemental Zn/kg from BZC or 0, 500, 650 and 800 mg supplemental Cu/kg from BCC. Broiler chicks fed those high inclusion rates of Zn did not show reduced weight gain in comparison to chicks fed no supplemental Zn. All high concentrations of supplemental Cu depressed chick weight gain in comparison to control chicks. (5) Experiment 4 involved two separate 4 x 2 factorial designs with supplemental Zn (0, 2500, 3500 and 4500 mg/kg) or Cu (0, 500, 750 and 1000 mg/kg) and two breeds of chicks (crossbred and commercial). Significant interactions for weight gain, food intake, gain:food and liver Cu suggested that the crossbred and commercial chicks responded differently to high concentrations of supplementary dietary Cu.

1alpha-hydroxycholecalciferol has little effect on phytate phosphorus utilization in laying hen diets.

Previous research in our laboratory demonstrated marked increases in phytate P utilization when P-deficient corn-soybean meal diets were supplemented with 1a-hydroxycholecalciferol [1alpha-(OH) D3] and fed to chicks. Our objective was to determine if 1alpha-(OH) D3 would improve phytate P utilization when supplemented to vitamin D-adequate laying hen diets. The five experimental treatments were 1) P-deficient corn-soybean basal diet [17% CP, 3.8% Ca, and 0.10% nonphytate NPP)], 2) basal with 2.5 microg/kg 1alpha-(OH) D3, 3) basal with 5 microg/kg 1alpha-(OH) D3, 4) basal with 10 microg/kg 1alpha-(OH) D3, and 5) basal with 0.35% supplemental inorganic P (0.45% NPP, positive control). Diets were fed to six replicate groups of 12 HyLine W-98 White Leghorn laying hens from 44 to 52 wk of age. Hen-day egg production was significantly depressed by 47 wk of age for the basal diet treatment and by 47, 49, and 48 wk of age, respectively, for the 2.5, 5, and 10 microg/kg of 1alpha-(OH) D3 treatments compared to the positive control diet. Supplementation with 5 or 10 microg/kg 1alpha-(OH) D3 did improve (P < 0.05) egg production, but egg production for those treatments was much lower than that for the 0.45% NPP treatment. Our results indicate that 1alpha-(OH) D3 did not substantially improve P utilization in laying hens fed corn-soybean meal diets.

Interrelationship between environmental temperature and dietary nonphytate phosphorus in chicks.

Four levels of nonphytate P (NPP; 0.2, 0.3, 0.4, and 0.5%; total P = 0.46, 0.56, 0.66, and 0.76%) and two temperatures (25 and 37 degrees C) were evaluated in chicks from 8 to 22 d. In experiment 1, crossbred male chicks (New Hampshire x Columbian) housed at 25 degrees C increased weight gain at all increasing NPP levels, but chicks exposed to 37 degrees C did not show increased weight gain beyond 0.3% NPP. In experiment 2, environmental temperature was not increased until d 15. Weight gain of crossbred male chicks fed the 0.2% NPP diet was similar at both temperatures, but chicks exposed to 37 degrees C had lower weight gains than chicks housed at 25 degrees C for all other NPP levels. On d 22 to 24, chicks that had been housed at 25 degrees C and fed 0.2, 0.3, and 0.5% NPP were moved to the 37 degrees C chamber to evaluate heat stress on older chicks. Chicks fed the 0.2% NPP diet showed 35% mortality within 6 h. In experiment 3, both male commercial (Ross x Ross) and crossbred chicks that had been housed at 25 degrees C and fed 0.2% NPP from 8 to 22 d showed increased signs of severe heat distress when exposed to 37 degrees C on d 22. Our results suggest that the NPP requirement for growth of 8-to-22-d-old chicks may be reduced by high temperature. However, a NPP deficiency may result in increased mortality or severe heat distress in older chicks that are exposed to an acute increase in temperature.

Efficacy of high available phosphorus corn in laying hen diets.

Our objective was to determine if high available phosphorus corn would provide sufficient available phosphorus (AP) to laying hens fed corn-soybean meal diets from 57 to 69 wk of age. Six replications of 12 Dekalb Sigma Leghorn hens were fed a normal yellow dent (YD) corn-soybean meal diet or high available phosphorus (HAP) corn-soybean meal diet without and with 0.04% supplemental inorganic P. The unsupplemented YD diet was calculated to contain 17% CP, 3.8% Ca, and 0.10% AP, and the unsupplemented HAP diet contained 17% CP, 3.8% Ca, and 0.16% AP. In addition, a positive control, YD diet (17% CP, 3.8% Ca, 0.45% AP) was also fed. The HAP corn was directly substituted for YD on a weight basis, and the amount of soybean meal was kept constant in all diets. Egg production, hen body weight, egg weight, egg mass, feed consumption, and feed efficiency were measured. The YD and the YD + 0.04% P treatments were terminated at 61 and 65 wk of age, respectively, due to severe depressions in egg production. Egg production and egg mass for hens fed HAP diets were not different (P > 0.05) from those of hens fed the 0.45% AP diet; however, hens fed the unsupplemented HAP diet did have lower hen body weights and feed intake (P < 0.05) compared to hens fed the positive control diet. Our results indicate that HAP corn contains more available P than normal YD corn and that hens can be fed HAP corn-soybean meal diets containing little or no P supplementation with only minimal effects on production performance.

Nutritional evaluation of dried tomato seeds.

Two samples of tomato seeds, a by-product of the tomato canning industry were evaluated to determine proximate analysis, amino acid content, and digestibility, TMEn, and protein efficiency ratio. Tomato seeds were also used to replace corn and soybean meal (SBM) in a chick diet on an equal true amino acid digestibility and TMEn basis. Tomato seeds were found to contain 8.5% moisture, 25% CP, 20.0% fat, 3.1% ash, 35.1% total dietary fiber, 0.12% Ca, 0.58% P, and 3,204 kcal/kg of TMEn. The total amounts of methionine, cystine, and lysine in the tomato seeds were 0.39, 0.40, and 1.34%, respectively, and their true digestibility coefficients, determined in cecectomized roosters, were 75, 70, and 54%, respectively. The protein efficiency ratio (weight gain per unit of protein intake) value when fed to chicks at 9% CP was 2.5 compared to 3.6 for SBM (P < or = 0.05). When corn-SBM diets were formulated on an equal true amino acid digestibility and TMEn basis, up to 15% tomato seeds could replace corn and SBM without any adverse affects on chick weight gain, feed intake, or gain:feed ratio from 8 to 21 d posthatch. Tomato seeds at any level in the diet did not significantly affect skin pigmentation. Although the protein quality of tomato seeds may not be as high as SBM, tomato seeds do contain substantial amounts of digestible amino acids and TMEn. When formulating diets on a true digestible amino acid and TMEn basis, tomato seeds can be supplemented into chick rations at up to 15% without any adverse affects on growth performance.