Effects of replacing a dietary antibacterial agent (zinc bacitracin) with copper salts in Cherry Valley Pekin meat ducks.

1. A study was conducted to investigate the effectiveness of high dietary copper concentrations obtained from tribasic copper chloride (TBCC, 58% copper) and copper sulphate pentahydrate (CuSO4, 25% copper) in replacing antibiotic growth promoters (AGP) in duck diets. 2. A total of 960 one-day-old Cherry Valley meat-strain ducks were divided into 3 treatment groups, with 8 replicates per treatment, in a 6-week feeding trial. The ducks were fed a basal diet supplemented with AGP (40 mg zinc bacitracin/kg and 40 mg garlicin/kg of diet) or 150 mg of Cu/kg of diet, given as either CuSO4 or TBCC. 3. The body weight, average daily gain, average daily feed intake and mortality of ducks were not affected by the dietary treatments. However, the feed/gain ratio of ducks that were fed TBCC diets was significantly lower than those of ducks that were fed CuSO4 diets and were similar to those in the AGP group. 4. TBCC increased the Cu content in the liver tissue of ducks compared with the content in those that were fed the diet supplemented with AGP. TBCC also increased the Fe and Zn content in breast muscles compared with that in ducks that were fed the diet supplemented with CuSO4. 5. The activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were significantly higher in the serum of ducks that received the diet supplemented with TBCC than AGP or CuSO4. TBCC treatment decreased the malondialdehyde (MDA) content in serum of ducks compared with groups supplemented with CuSO4. 6. No significant difference was observed in liver or muscle fat content among the different dietary treatment groups. The serum low-density lipoprotein cholesterol concentration was lower in ducks fed AGP diets than those fed CuSO4 diets. 7. It was concluded that the replacement of AGP with 150 mg of Cu/kg of feed from TBCC improved the feed efficiency, trace mineral deposition and antioxidant status more than when the source of copper was CuSO4.

Dietary thyroxine induces molt in chickens (Gallus gallus domesticus).

Thyroxine increases during a molt in wild and captive birds, and thyroidectomy prevents induction of molt. This trial examined the effect of dietary thyroxine on molt induction molt in chickens (laying hens, 59 weeks of age). In a completely randomized design (n=15 hens/replication; 6 replications/treatment), hens were randomly assigned to either a traditional molting program consisting of feed withdrawal (FWD), or to diets containing 40 mg thyroxine/kg diet (HT), 20 mg thyroxine/kg diet (LT), or 40 mg thyroxine from thyroactive iodinated casein/kg diet (TIC). The molting treatment lasted 7-13 d, until egg production reached 0%. After molt induction, birds had ad libitum access to the same diet, until egg production was re-initiated and maximized ( approximately 56 d). All treatments induced molt, based upon cessation of egg laying and regression of ovary and oviduct. Birds on FWD treatment lost more body weight during the molting period, but gained more after molt compared to thyroxine treatments (P<0.01 for each), although all body weights were similar when egg production was maximized. Data demonstrate that oral thyroxine, in purified or non-purified form, induces a molt and may enhance animal well-being by reducing the need for FWD.

Effect of different non-chloride sodium sources on the performance of heat-stressed broiler chickens.

1. One hundred and eighty 1-d-old broiler chicks were used to evaluate the effect upon broiler performance during severely hot summer months of three different sodium salts: sodium bicarbonate (NaHCO3), sodium carbonate (Na2CO3) and sodium sulphate (Na2SO4), in starter and finisher diets having an identical electrolyte balance (DEB) of 250 mEq/kg. 2. The non-chloride sodium salts were added to contribute the same amount of sodium and were substituted at the expense of builder's sand in the basal diets containing common salt (NaCl) as Na and Cl source. 3. Each diet was fed to three experimental units having 15 chicks each until 42 d of age. Severe heat-stress conditions, maintained in the rearing room, were indicated by high average weekly room temperature (minimum 29.3 degrees C; maximum 38.0 degrees C). 4. Diets containing sodium salts gave better body weight gain, feed intake and feed to gain ratio than the control diet. Sodium salts also enhanced water intake as well as water to feed intake ratio. This effect was more pronounced in broilers fed NaHCO3 supplement (with NaCl in the basal diets). 5. The increased water intake resulted in lower body temperature in heat-stressed birds fed NaHCO3 supplemented diet than in birds fed other sodium salts. A lower mortality rate was noted with NaHCO3 (15.15%), Na2CO3 (13.64%) and Na2SO4 (15.15%) supplements than with the control (33.33%) treatment. 6. Better carcase and parts yield were observed in sodium supplemented broilers. Sodium salts reduced the alkalotic pH and enhanced the blood sodium content, which ultimately improved the blood electrolyte balance and overall performance of heat-stressed broilers. 7. Supplementing broiler diets with sodium salts improved the live performance of heat-stressed broilers and better productive performance was noted with NaHCO3 than other sodium supplements.

Physiological responses of broiler chickens to heat stress and dietary electrolyte balance (sodium plus potassium minus chloride, milliequivalents per kilogram).

Individually caged male Cobb broilers (24), 44 d of age, were used to evaluate effects of heat stress (1 d of data collection) and dietary electrolyte balance (DEB; Na + K - Cl, mEq/kg from 1 d of age). During summer rearing, mortality was variable, but DEB 240 improved growth, feed conversion ratio, water intake, and water:feed ratio vs. DEB 0. The temperature sequence for heat stress was 24 to 32 degrees C in 30 min, 32 to 36 degrees C in 30 min, 36 to 37 degrees C in 15 min, and 37 to 41 degrees C in 45 min. Maximum temperature was held for 15, 60, 90, or 360 min for data collection (relative humidity averaged 42 +/- 7%). Results from the same room before and after heat stress were analyzed by DEB (1-factor ANOVA) and before vs. after heat stress compared across DEB (2-sample t-test). Heat stress decreased blood Na, K, and pCO2, and lymphocytes but increased heterophils. Blood HCO3 rose, Cl declined, and hematocrit gave a concave pattern (lowest at DEB 120) as DEB increased. After heat stress, DEB 0 decreased blood Na and K, and DEB 0 and 120 levels decreased blood HCO3. After heat stress blood pCO2 and hemoglobin decreased with DEB 240, but it had highest pCO2, a key factor. The DEB 120 gave longest times to panting and prostration with DEB 0 and 240 results lower but similar statistically. In heat stress, DEB 360 was excessive, DEB 120 and 240 were favorable, and DEB 0 was intermediate based on hematology, panting, and prostration responses.

Dietary sodium bicarbonate, cool temperatures, and feed withdrawal: impact on arterial and venous blood-gas values in broilers.

Sodium bicarbonate (NaHCO3) has been used successfully in mammals and birds to alleviate pulmonary hypertension. Experiment 1 was designed to provide measurements of arterial and venous blood-gas values from unanesthetized male broilers subjected to a cool temperature (16 degrees C) challenge and fed either a control diet or the same diet alkalinized by dilution with 1% NaHCO3. The incidences of pulmonary hypertension syndrome (PHS, ascites) for broilers fed the control or bicarbonate diets were 15.5 and 10.5%, respectively (P = 0.36, NS). Non-ascitic broilers fed the control diet were heavier than those fed the bicarbonate diet on d 49 (2,671 vs. 2,484 g, respectively); however, other comparisons failed to reveal diet-related differences in heart weight, pulse oximetry values, electrocardiogram amplitudes, or blood-gas values (P > 0.05). When the data were resorted into categories based on right:total ventricular weight ratios (RV:TV) indicative of normal (RV:TV < 0.28) or elevated (RV:TV > or = 0.28) pulmonary arterial pressures, broilers with elevated RV:TV ratios had poorly oxygenated arterial blood that was more acidic, had high partial pressure of CO2 (PCO2), and had higher HCO3 concentrations when compared with broilers with normal RV:TV ratios. Experiment 2 was conducted to determine if metabolic variations associated with differences in feed intake or environmental temperature potentially could mask an impact of diet composition on blood-gas values. Male broilers maintained at thermoneutral temperature (24 degrees C) either received feed ad libitum or had the feed withdrawn > or = 12 h prior to blood sampling. Broilers fed ad libitum had lower venous saturation of hemoglobin with O2, higher venous PCO2, and higher arterial HCO3 concentrations than broilers subjected to feed withdrawal. Broilers in experiment 2 fed ad libitum and exposed to cool temperatures (16 degrees C) had lower arterial partial pressure of O2 and higher venous PCO2 than broilers fed ad libitum and maintained at 24 degrees C. Overall, these results demonstrate that changes in diet composition (control vs. 1% NaHCO3 diets) had minimal impact on arterial and venous blood-gas variables when compared with the more dramatic differences associated with feed intake (ad libitum vs. > or = 12 h withdrawal), environmental temperature (24 vs. 16 degrees C), and the pathogenesis associated with PHS (RV:TV < 0.28 vs. > or = 0.28).

Dietary electrolyte balance for broiler chickens exposed to thermoneutral or heat-stress environments.

Ross male broiler chicks (n = 480) on new litter were used in a randomized block design with two blocks (environmental rooms) and four treatments having four replicate pens (1.0 x 2.5 m; 15 chicks) each to evaluate dietary electrolyte balance (DEB; P < 0.05). Two rooms were 1) thermoneutral (Weeks 1 through 6, with decreasing maximum from 32 to 25 degrees C and minimum from 28 to 19 degrees C; relative humidity 49 to 58%) and 2) cyclic daily heat stress (Weeks 1 and 2, thermoneutral; Weeks 2 through 6, maximum temperatures 35, 35, 33, and 33 degrees C, respectively; and minimum temperatures 23, 20, 19, and 19 degrees C, respectively; relative humidity 51 to 54%). The DEB treatments (0, 140, 240, or 340 mEq Na + K - Cl/kg) had NaHCO3 plus NH4Cl, or KHCO3, or both added to corn-soybean meal mash basal diets with 0.30% salt (NaCl). In the thermoneutral room, DEB 240 increased 42-d weight gain and 44-d lymphocyte percentage and decreased heterophil percentage and heterophil to lymphocyte ratio compared to the DEB 40 treatment. The DEB 240 diets had 0.35 and 0.35% Na and 0.37% and 0.29% Cl in starter (0.75% K) and grower (0.67% K) diets, respectively. No DEB treatment differences were found in the heat stress room. For combined rooms, 42-d feed intake was higher for DEB 240 than for DEB 40. The 21-d weight gain was higher for DEB 240 than for DEB 40 or 140; and 21-d feed/gain was lower for DEB 40 than for DEB 340. The predicted maximum point of inflection for 21- and 42-d weight gains were DEB 250 and 201, with highest 42-d feed intake at 220.

Dietary electrolyte balance for broiler chickens under moderately high ambient temperatures and relative humidities.

Cobb male broiler chicks (1,000) on new litter were used to evaluate effects of dietary electrolyte balance [DEB; Na+K-Cl, milliequivalents (mEq) per kilogram] under tropical summer conditions. Corn-soybean meal-based mash diets had salt (NaCl) alone or in combination with one or more supplements: sodium bicarbonate (NaHCO3), ammonium chloride (NH4Cl), or potassium bicarbonate (KHCO3). A completely randomized design, with five starter and grower feed treatments (control: 145, then 130 mEq/kg; or 0, 120, 240, or 360 mEq/kg throughout) and four replicate pens (1.5 x 3.2 m) per treatment (50 chicks per pen), was used. Diets were analyzed for Na, K, and Cl for confirmation. There were no significant (P < 0.05) effects of treatments on mortality or processing parameters. Water intake increased linearly with increasing DEB, giving higher litter moistures and lower rectal temperatures. Blood HCO3 and pH increased with the highest DEB (360 mEq/kg) causing respiratory alkalosis. The DEB of 240 mEg/kg gave best weight gain and feed conversion ratio, and ideal DEB predicted by regression analyses were 186 and 197 mEq/kg from 0 to 21 d of age and 236 and 207 mEq/kg of feed from 0 to 42 d, respectively. These DEB corresponded to estimated (interpolated) values in predicted optimal 186 to 197 mEq/kg starter of Na 0.38 to 0.40% and Cl 0.405 to 0.39% (K = 0.52%), in 207 to 236 mEq/kg starter, Na 0.409 to 0.445% and Cl 0.326 to 0.372% Cl (K = 0.52%), and in grower Na 0.41 to 0.445%, Cl 0.315 to 0.267% (K = 0.47%).

Interactive effects of dietary sodium and chloride on the incidence of spontaneous cardiomyopathy (round heart) in turkeys.

Two pen trials were conducted in Utah, altitude 1,630 m, with Large White female turkey poults to evaluate effects of dietary Na and chloride (Cl) concentrations on live performance and deaths caused by spontaneous cardiomyopathy (STC, "round heart") from 0 to 35 d of age. A randomized block 2 x 2 factorial arrangement with four replicate pens per treatment was used. Pen size was 3.8 x 5.6 m. In each trial, four starter diets were formulated from a common basal diet (corn-soy-meat) to obtain the following sodium and chloride concentrations: High Na (0.24%):High Cl (0.40%); High Na (0.24%):Low Cl (0.16%); Low Na (0.14%):High Cl (0.40%); and Low Na (0.14%):Low Cl (0.16%). Supplements were NaCl, NaHCO3, NH4Cl, or combinations. After laboratory analysis, true values of Na were slightly lower than expected, Cl was near expected values to slightly low, and K was 1.145%. Body weight and feed conversion ratio at 35 d of age were unaffected in both trials. In both experiments, STC mortality was significantly reduced by the Low Na:High Cl treatment compared to the other treatments. In conclusion, a diet containing 0.10 to 0.12% Na and 0.38 to 0.40% Cl, significantly improved poult livability by reducing STC mortality without adverse effects on poult weight or feed conversion ratio.

Evaluation of sodium bicarbonate, chloride, or sulfate with a coccidiostat in corn-soy or corn-soy-meat diets for broiler chickens.

During the period from January to June, combined-sex broiler chickens were inoculated with coccidia via drinking water at 14 d of age. In a completely randomized design (eight replicate pens; 88 chicks per pen) using built-up litter, experimental diets contained monensin plus 0.20% dietary sodium bicarbonate (SBC), which provided 0.054% sodium and 0.144% bicarbonate. Treatment with SBC significantly improved coccidial lesion score, 45-d body weight, and feed efficiency compared with monensin alone. In a 2 x 5 factorial trial using built-up litter pens (eight replicate pens; 88 chicks per pen) vs. each ionophore alone, 0.20% dietary SBC with monensin significantly improved body weight, uniformity, and feed efficiency; 0.20% SBC with halifuginone, lasalocid, monensin, or salinomycin significantly reduced mortality; and 0.20% SBC with lasalocid, monensin, or salinomycin significantly increased breast meat yield. In a 2x4 factorial trial (12 replicate pens; 88 chicks per pen) on built-up litter, corn-soy and corn-soy-meat diets (higher potassium, lower chloride) with monensin were evaluated using 0.054% sodium from SBC, NaCl, or sodium sulfate decahydrate (SSD). With both diet types, SBC (0.20%) or NaCl (0.139% extra) significantly improved weight uniformity, feed efficiency, mortality, and breast meat yield; however, the SSD results were closer to controls. In a 21-d battery brooder test using similar diets and design (2x4 factorial; 4 replicate pens; 10 chicks per pen), SBC and NaCl significantly reduced coccidial lesion scores; SSD produced a significant, but weaker effect. Extra NaCl significantly increased water intake (approximately 37%), water excretion (approximately 27%), and litter moisture (approximately 22%) with both diet types. The SSD did not affect water intake.