Evaluation of a Feed-Grade Enzyme in Broiler Diets to Reduce Pododermatitis

Nutritional and management interventions are needed to reduce the incidence of pododermatitis in poultry. In this study, enzyme (Allzyme Vegpro) supplementation of corn-soybean meal-based broiler diets was evaluated in an effort to reduce total N and NH₃ production and its effect on pododermatitis in broiler chickens. A total of 1,600 mixed-sex chicks were raised on floor pens in a design involving 2 × 2 × 2 arrangement of protein level [high or low], protein source [all vegetable (Veg) or vegetable plus animal (Veg + Ani)], and enzyme [with or without enzyme supplementation (0.06%)], on a 4-stage feeding program (4 replicate pens/treatment; 50 birds/pen). In addition to live performance, the feet were scored for incidence of lesions on all birds on 28, 42, and 57 d of age, and the severity was recorded as none, mild, and severe. Pooled gut samples were collected at 57 d of age to determine viscosities of fore- and hindgut contents. Pooled litter samples were analyzed for moisture, total N, and NH₃ production at 14, 28, 42, and 57 d of age. Live performance of birds did not vary among the treatments (P > 0.05). The incidence of pododermatitis was significantly affected by protein source at 42 d (P < 0.05), with birds fed all-vegetable diets showing higher incidence and severity than those fed vegetable plus animal diets. At 57 d of age, birds reared on all-vegetable diets with enzyme supplementation showed a lower incidence of mild footpad lesions compared with other treatments. Enzyme supplementation reduced viscosity of the gut contents irrespective of the protein level or protein source. Higher levels of litter NH₃ were observed with high-protein diets (28 and 42 d), all-vegetable diets (28 d), and with enzyme supplementation (28 and 42 d). In this study, enzyme supplementation had little effect on litter total N and NH₃ production levels, but reduced viscosity of the gut contents and severity of pododermatitis in older birds.     

Effect of High-Protein and All-Vegetable Diets on the Incidence and Severity of Pododermatitis in Broiler Chickens

The incidence and severity of pododermatitis in broiler chickens is of great concern to the broiler industry, both from product quality and animal welfare standpoints. A total of 1,600 birds were raised in floor pens in a design involving a 2 × 2 × 2 arrangement of protein level [high or low], protein source [all vegetable (VEG) or vegetable plus animal (VEG + ANI)], and sex (male and female) on a 4-stage feeding program (50 birds per pen; 4 pens of males and 4 pens of females per treatment). In addition to live performance, the feet were scored on all birds on 29, 43, and 54 d of age, and the severity of lesions was recorded as none, mild, or severe. A subsample of birds was processed at the end of the experiment to evaluate carcass yields. Pooled litter samples were collected on 29, 43, and 54 d of age for total and NH₃-N analysis. Protein level had a significant (P < 0.05) effect on BW on 14, 29, and 43 d of age. At 43 and 54 d of age, BW was significantly influenced by protein source and sex. Chilled carcass yields did not differ between the treatments (P > 0.05). Footpad lesions were significantly affected by protein level, protein source, and sex. At 29 d of age, all lesions were mild in severity and varied significantly in incidence by protein source (31% for VEG vs. 41% for VEG + ANI). At 54 d of age, both protein level and protein source significantly increased the incidence and severity of footpad lesions. Incidence of pododermatitis was higher for males (61%) than females (55%). Litter total N was significantly affected by protein level and protein source. The litter NH₃-N content, although not significant, except for 29 d of age, showed an increasing trend for each feeding period. The incidence and severity of pododermatitis was significantly affected by protein level, protein source, sex, and age. Hence, nutritional factors play a significant role in the etiology of pododermatitis in broilers.     

Windrowing poultry litter after a broiler house has been sprinkled with water

In-house windrowing of poultry litter between broiler flocks has been promoted as a management practice to improve the litter condition upon chick placement. Before the onset of the current study, low-pressure sprinklers were used during the grow-out period in a broiler house. Different methods of windrowing were then utilized to determine the effect each had on litter composition. Covered, turned, and static 9 d windrow treatments, and one non-windrowed control were applied to a broiler house containing litter used over multiple flock grow-outs. The house was divided into 16 6 × 6 m plots with each treatment being applied to 4 blocks within the house. Litter from each plot was analyzed for particle size, moisture, N, NH₃, P, K, pH, and temperature over a 20-day period, with d 20 representing 7 d after chick placement. All variables except particle size were statistically different. Of all the treatments, the covered treatment showed the greatest reduction in moisture over the 20-day period. Nitrogen content was lowest in the turned treatment. Ammonia decreased from d 9 to 20. Both the covered and static treatments were able to reach recommended temperatures in both the core and the periphery of the windrows. Conclusively, in-house windrowing after utilizing low-pressure sprinklers did not improve N retention, reduce NH₃ volatilization, or decrease P or K in the litter compared to the control. However, the temperatures obtained in the periphery and core of the covered and static treatments show potential for eliminating pathogens present in the litter.     

Precipitation and Nitrogen Deposition Alter Litter Decomposition Dynamics in Semiarid Temperate Steppe in Inner Mongolia,China

Plant litter decomposition is one of the most important links connecting plants to the soil through the carbon (C) and nitrogen (N) cycles. Climate change scenarios predict changes in precipitation and N deposition, and previous studies have demonstrated that increases in the availability of water and N affect the litter decomposition rate and nutrient release. We studied the effects of increased N deposition and precipitation on changes in the remaining mass and the C and N contents of shoot litter after decomposition in a typical steppe in Inner Mongolia, China. The treatments included the addition of NH₄NO₃ at rates equivalent to 0, 25, 50, and 100 kg ? N ? ha^? 2yr^? 1 with and without added water. The addition of water proved to be a more effective practice than amendment with NH₄NO₃ for improving the litter decomposition rate; the addition of water significantly increased the rate of litter decomposition (P < 0.001), whereas the addition of N alone had no apparent effect on litter mass loss. However, a repeated measures analysis of variance (ANOVA) showed that the interaction of water and N significantly affected both mass loss and litter N content (P < 0.05), and a linear relationship was identified between litter mass loss and litter decomposition time (P < 0.001). No correlation was found between litter mass loss and organic C content, but a significant positive correlation was found between residual litter mass and N content (P < 0.01). Although the study was conducted over a relatively short period, our results indicate that increased precipitation could potentially promote litter decomposition, whereas increased N input has little effect. The effects of time on litter mass loss and residual C and N concentrations indicate the need for long-term trials that measure the complete process of litter decomposition and the peaks of C and N release.     

Effect of dietary supplementation of medium-chain fatty acids on growth performance and prevalence of carcass defects in broiler chickens raised in different stocking densities

A 3 × 3 factorial experiment was conducted to examine the effect of medium-chain fatty acids (MCFA) on performance and occurrence of carcass defects in broiler chickens raised in stocking densities of 14, 16, and 18 birds/m². A total number of 720 Ross 308 broiler chicks that were 1 d old were reared up to 49 d of age. Corn- and soybean meal (SBM)–based starter and grower diets were supplemented with 0, 1.5, and 2 g/kg Aromabiotic and provided to the birds ad libitum. Inclusion of 2 g/kg Aromabiotic in the diet significantly improved weight gain of the birds during 1 to 21 d of age compared with control birds (P< 0.001). A significant reduction in mortality (P= 0.004) and a significant increase in European performance efficiency index (EPEI;P= 0.036) were noted in the birds that received diets containing 2 g/kg Aromabiotic compared with control birds at 49 d of age. The birds grown in a placement density of 18 birds/m²had significantly improved FCR along with reduced feed intake (FI) during 1 to 49 d of age compared with those reared in a density of 14 birds/m². The mean EPEI was significantly greater in the birds raised in a density of 16 birds/m²(P< 0.001). At 48 d of age, litter caking was significantly increased in the birds raised in a density of 18 birds/m²and decreased in the birds that received dietary supplementation of Aromabiotic (P< 0.05). The influence of dietary Aromabiotic was significant related to reduced incidence and severity of footpad lesions and hock burns (P< 0.01). Frequency of lesions with a score of 2 to 5 on footpad and hock significantly increased for the birds raised in densities higher than 14 birds/m². It was concluded that dietary supplementation of 2 g/kg Aromabiotic improved early productive performance of broiler chickens and enhanced the PEI mainly due to decreased mortality. Dietary Aromabiotic improved broiler welfare as indicated by reduced foot defects in the birds raised in placement densities of 16 and 18 birds/m².     

Effect of a Metabolic Stimulant on Ammonia Volatilization from Broiler Litter

High NH₃ concentrations in broiler and turkey houses can adversely affect bird performance and the environment when exhausted into the atmosphere. Acidifying amendments have been used in poultry houses to reduce NH₃ levels, but the acidifiers are caustic and may not be effective for the entire growout of 8 to 9 wk. In this 45-d study, the effect of a metabolic stimulant (biostimulant), Bio-Kat, on exhaust NH₃ concentrations from chambers containing broiler litter (supplemented daily with layer manure slurry) was evaluated. Average NH₃ concentration in the exhaust air from the chambers containing Bio-Kat-treated litter was reduced by 61% compared with untreated litter. Also, ammoniacal-N concentration in the Bio-Kat-treated litter was double that of untreated litter at the end of the study. The Bio-Kat amendment was most effective during the first 10 to 12 d, and its efficacy decreased over time. Additional work is required to evaluate the more concentrated formulation (for duration of effectiveness and application rate) and identify the proper method of application (i.e., incorporation vs. broadcasting on the surface).     

Impact of manganese amino acid complex on tissue-specific trace mineral distribution and corpus luteum function in gilts

Functional corpora lutea (CL) are required for pregnancy establishment and gestational maintenance in swine, and CL function is susceptible to environmental influences. Manganese (Mn) could be critical in regulating CL function since it is a component of the antioxidant enzyme Mn superoxide dismutase (MnSOD) as well as enzymes involved in cholesterol and steroid hormone synthesis. We hypothesized that a more bioavailable dietary Mn source would increase Mn content in the CL thereby influencing luteal function during the mid-luteal phase of the estrous cycle. Postpubertal gilts (n = 32) were assigned to one of four gestation diets. The control diet (CON) met or exceeded National Research Council (2012) requirements and was formulated to contain 20 parts per million (ppm) of added Mn in the form of Mn sulfate. Three additional diets included 20 (treatment [TRT]1), 40 (TRT2), or 60 (TRT3) ppm of added Mn from a Mn–amino acid complex (Availa-Mn; Zinpro Corporation) instead of Mn sulfate. Dietary treatment began at estrus synchronization onset and continued through 12 days post estrus (dpe) of the ensuing estrous cycle. Blood samples were collected at estrus onset, which was assigned as 0 dpe, as well as 4, 8, and 12 dpe. Gilts were euthanized and tissues were collected at 12 dpe. Serum progesterone (P₄) increased (P < 0.01) from 0 to 12 dpe but was unaffected by dietary treatment (P = 0.15) and there was no effect of the interaction between day and treatment (P = 0.85). Luteal Mn content increased (P ≤ 0.05) by 19%, 21%, and 24% in gilts fed TRT1, TRT2, and TRT3, respectively, compared to CON. Luteal P₄ concentrations decreased (P = 0.03) 25%, 26%, and 32% in gilts fed TRT1, TRT2, and TRT3, respectively, compared to CON. Relative to CON gilts, CL calcium content decreased (P = 0.02) by 36%, 24%, and 34% for TRT1, TRT2, and TRT3 gilts, respectively. Collectively, these data support the hypothesis that feeding a more bioavailable Mn source increases Mn accumulation in CL tissue. If and how this influences CL function may be related to altered luteal P₄ concentrations.     

The effect of dietary lysozyme with EDTA on growth performance and intestinal microbiota of broiler chickens in each period of the growth cycle

Lysozyme is a potential replacement for antibiotics in the poultry industry. Two trials were conducted using new or used litter to determine the effect of 100 ppm lysozyme in feed on growth performance and intestinal microbiota of broiler chickens in each period of the growth cycle. The new litter trial and used litter trial were each analyzed as a one-way analysis of variance with length of time in which 100 ppm lysozyme was fed to the birds as the main factor (no lysozyme d zero to 35; positive lysozyme d zero to 4; positive lysozyme d 5 to 14; positive lysozyme d 15 to 24; positive lysozyme d 25 to 35; positive lysozyme d zero to 35; positive virginiamycin d zero to 35). Effects of lysozyme were not detected under clean conditions (P > 0.05). When used litter was provided, growth performance was not improved by lysozyme (P > 0.05). However, feeding lysozyme to birds from d 5 to 14 and throughout the trial reduced the number of E. coli in the ileum compared with feeding virginiamycin (positive lysozyme d 5 to 14 and zero to 35, and virginiamycin d zero to 35: 1.7 × 10⁴ cfu g⁻¹, 1.9 × 10⁴ cfu g⁻¹ and 9.3 × 10⁴ cfu g⁻¹, respectively) to birds (P < 0.05). Dietary lysozyme at 100 ppm can change intestinal microbiota of broiler chickens.     

Evaluation of a Competitive Exclusion Culture and Megan Vac 1 on Salmonella Typhimurium Colonization in Neonatal Broiler Chickens

The present study was designed to evaluate the effect of individual or simultaneous application of 2 products, a competitive exclusion culture (CEC) or Megan Vac 1 (MV), for bioefficacy in reducing Salmonella Typhimurium (ST) cecal colonization in broiler chicks following experimental challenge. In experiment 1, CEC and MV were applied to day-of-hatch broiler chicks, and chicks were experimentally challenged with ST approximately 48 h later. In control chicks, ST was recovered at a level of 3.84 log₁₀ cfu/g following direct plating of cecal contents, and 12 of 19 (63.15%) cultured individual ceca were positive following selective enrichment. In chicks receiving CEC by spray application on day of hatch, a numerical reduction in ST recovered from cecal contents (2.63 log₁₀ cfu/g) and a significant reduction (P < 0.05) in recovery of ST from cultured ceca following selective enrichment (4 of 18, or 22.2%) was observed when compared with controls. Significant reductions in ST cecal colonization in chicks treated with MV alone were not observed in experiment 1. In experiment 2, chicks received day-of-hatch spray application of CEC alone, MV alone, or CEC and MV as a combined application immediately prior to or within 24 h of chick placement. When chicks were experimentally challenged with ST 48 h posthatch, significant reductions (P < 0.05) in cecal colonization by ST were observed with each experimental group when compared with nontreated controls. These data suggest that both commercially available products, alone or in combination, are efficacious in reducing cecal colonization in broiler chicks challenged with ST.     

Effect of Various Litter Amendments on Ammonia Volatilization and Nitrogen Content of Poultry Litter

Ammonia volatilization from poultry manure contributes to atmospheric N pollution, negatively affects poultry performance, and decreases the fertilizer value of manure. The objective of this study was to evaluate the effects of alum [Al₂(SO₄)₃·14H₂ O], liquid alum, high acid alum (A7), aluminum chloride (AlCl₃·6H₂ O), fly ash, Poultry Litter Treatment (PLT), and Poultry Guard (PG) litter amendments on NH₃ volatilization and N contents in litter. Two laboratory studies were conducted for 42 d each. The treatments in experiment 1, which were mixed in the upper 1 cm of litter, were 4 g of alum, 8 g of alum, 8.66 g of liquid alum, 17.3 g of liquid alum, 11.2 g of A7, 22.4 g of A7, 4 g of PG, 4 g of PLT, 4 g of fly ash, and 4 g of AlCl₃/100 g of litter. The treatments for experiment 2 were identical to experiment 1, except the fly ash treatment was dropped and an additional 4 g of alum/100 g of litter treatment was added, which was incorporated totally within the litter. The various rates of dry alum, liquid alum, and A7 significantly decreased NH₃ volatilization compared with the controls, with reductions ranging from 77 to 96% for experiment 1 and from 78 to 96% for experiment 2, respectively. Poultry Litter Treatment decreased NH₃ volatilization by 76 and 87% for experiment 1 and 2, respectively. Aluminum chloride decreased NH₃ volatilization by 48 and 92% for experiment 1 and 2, respectively. Litter treated with alum, liquid alum, A7, PLT, and AlCl₃ had a lower pH and a greater N content than the controls in experiment 1 and 2. In contrast, PG and fly ash resulted in a greater pH and were ineffective in decreasing NH₃ volatilization and increasing N contents in experiment 1. However, in experiment 2, PG was effective in reducting NH₃ loss. In this study, the decreased NH₃ volatilization was chiefly associated with reduction in litter pH.     

Characteristics of Gas Generation (NH3, CH4, N2O, CO2, H2O) From Horse Manure Added to Different Bedding Materials Used in Deep Litter Bedding Systems

The aim of this study was to analyze the influence of horse manure added to different bedding materials on the generation of gases (ammonia (NH₃), nitrous oxide, carbon dioxide, methane, water vapor) from deep litter bedding under standardized laboratory conditions. Two different types of straw (wheat and rye) and wood shavings were analyzed. The deep litter (substrate) was made of 25 kg of the respective bedding material, 60 kg horse feces, and 60 L ammonium chloride solution (urea), and spread out in identical chambers over 19 days (n = 3). On days 1, 8, 15, and 19, total nitrogen, total carbon, and dry matter content of the substrate, as well as the pH in 500-g samples, were measured along with. At the end of each test period, the nitrite nitrogen, nitrate nitrogen, and ammonium nitrogen contents of the leachate were analyzed. The wheat straw substrate emitted the highest concentration of NH₃ (4.31 mg/m³; P < .0001) and the wood shavings substrate emitted the lowest (1.73 mg/m³; P < .0001); the rye straw substrate generated 3.05 mg/m³. In addition, significant differences occurred during days 1 to 3 with respect to the generation of the gases NH₃, methane, nitrous oxide, carbon dioxide, and water vapor, and after the opening of the chamber on day 15. The nitrogen losses through the leachate occurred mainly in the form of nitrate, where the leachate from the wheat straw substrate had a significantly higher amount of nitrate nitrogen (44.56 mg) as compared with the leachates of the rye straw (14.49 mg; P ≤ .0001) and the wood shaving substrates (22.62 mg; P = .0010).     

Alternative bedding materials and litter depth impact litter moisture and footpad dermatitis

A function of bedding material in poultry houses is to absorb and release moisture. New bedding is commonly placed at inadequate depths in houses. Pine shavings are the industry standard for bedding material in the majority of the United States, but can be hard to obtain or costly. Alternative materials were tested for moisture absorption and retention. Peat moss and chopped wheat straw were found to absorb nearly 8× and 7× their own weight in moisture, respectively. Peat moss was then used in a broiler study and compared to fresh and used pine shavings for 6 weeks. Body weight was lower at d 7 for the used litter and peat moss treatment compared to fresh shavings with no differences at d 42. No differences in ammonia generation or litter pH were observed. Litter moisture was higher for peat moss through d 14. Paws were better in the fresh shaving and peat moss pens than used shaving pens at both d 21 and 42. Next, different depths of used and fresh shavings on footpad dermatitis (FPD) were examined. Trials 1 and 2 compared 2.5, 7.6, and 12.7 cm of fresh shavings or used litter, respectively. In Trial 1, 2.5 cm had higher litter moisture than 7.6 and 12.7 cm at d 21, 28, and 35 (P < 0.05). The 12.7 cm had better paw scores than 2.5 cm at d 21 and 35 (P < 0.05). In Trial 2, 12.7 cm had lower litter moisture than 2.5 cm at d 28, 35, and 42 (P < 0.05). The paws in 12.7 cm were better than those in 2.5 cm at d 35 and 42 (P < 0.05). There was little difference in paw quality and litter moisture between 7.6 and 12.7 cm litter depth in both trials. Peat moss may be an acceptable alternative bedding material and should be evaluated on a commercial scale in areas where it can be obtained economically. These findings suggest that broiler houses should have at least 7.6 cm of litter to control litter moisture levels and reduce FPD.     

The influence of extended supplementation of quebracho extract to beef steers consuming a hay diet on digestion,ruminal, and blood parameters

The addition of natural plant secondary compounds to ruminant feed has been extensively studied because of their ability to modify digestive and metabolic functions, resulting in a potential reduction in greenhouse gas emissions, among other benefits. Condensed tannin (CT) supplementation may alter ruminal fermentation and mitigate methane (CH₄) emissions. This study’s objective was to determine the effect of quebracho CT extract [QT; Schinopsis quebracho-colorado (Schltdl.) F.A. Barkley & T. Meyer] within a roughage-based diet on ruminal digestibility and kinetic parameters by using the in situ and in vitro gas production techniques, in addition to blood urea nitrogen (BUN) and ruminal (volatile fatty acid [VFA], NH₃-N, and protozoa count) parameters. Twenty rumen-cannulated steers were randomly assigned to four dietary treatments: QT at 0%, 1%, 2%, and 3% of dry matter (DM; QT0: 0% CT, QT1: 0.70% CT, QT2: 1.41% CT, and QT3: 2.13% CT). The in situ DM digestibility increased linearly (P = 0.048) as QT inclusion increased, whereas in situ neutral detergent fiber digestibility (NDFD) was not altered among treatments (P = 0.980). Neither total VFA concentration nor acetate-to-propionate ratio differed among dietary treatments (P = 0.470 and P = 0.873, respectively). However, QT3 had lower isovalerate and isobutyrate concentrations compared with QT0 (P ≤ 0.025). Ruminal NH₃ and BUN tended to decline (P ≤ 0.075) in a linear fashion as QT inclusion increased, suggesting decreased deamination of feed protein. Ruminal protozoa count was reduced in quadratic fashion (P = 0.005) as QT inclusion increased, where QT1 and QT2 were lower compared with QT0 and QT3. Urinary N excretion tended to reduce in a linear fashion (P = 0.080) as QT increased. There was a treatment (TRT) × Day interaction for in vitro total gas production and fractional rate of gas production (P = 0.013 and P = 0.007, respectively), and in vitro NDFD tended to be greater for QT treatments compared with no QT inclusion (P = 0.077). There was a TRT × Day interaction (P = 0.001) on CH₄ production, with QT3 having less CH₄ production relative to QT0 on day 0 and QT2 on days 7 and 28. Feeding QT up to 3% of the dietary DM in a roughage-based diet did not sacrifice the overall DM digestibility and ruminal parameters over time. Still, it is unclear why QT2 did not follow the same pattern as in vitro gas parameters. Detailed evaluations of amino acid degradation might be required to fully define CT influences on ruminal fermentation parameters and CH₄ production.     

Instrumentation for Evaluating Differences in Ammonia Volatilization from Broiler Litter and Cake

Greater understanding of the mechanisms affecting NH₃ volatilization from reused broiler bedding is needed to determine pathways for mitigating NH₃ emissions. A chamber acid trap (CAT) system was developed to provide an improved laboratory method for determining NH₃ volatilization from litter or cake samples and for assessing treatment technologies to decrease NH₃ losses from poultry litter. The CAT system offers precision control of air flow rate through sample chambers as well as straightforward, precise determination of the amount of N volatilized. This article outlines the basic setup of the CAT system. The system can be utilized and modified for researching specific mechanisms involving physical, chemical, or biological treatments affecting NH₃ volatilization from litter or cake.     

Effects of an Aluminum Sulfate and Ferric Chloride Blend on Poultry Litter Characteristics in Vitro

Previous studies have applied various concentrations of aluminum sulfate and ferric chloride separately to poultry litter to reduce environmental pollution and increase chicken productivity. In the present study, we investigated the effect of using a blend of these 2 chemicals under 5 different treatments: control (no addition), 50 + 50, 25 + 50, 50 + 25, and 25 + 25 g/kg of litter, which consisted of fresh chicken manure (1 kg) and sawdust (4 kg) thoroughly mixed in a 70 × 47 × 43 cm box. NH₃ and CO₂ volatilizations, pH, electrical conductivity (EC) and moisture content of the poultry litter were assessed weekly up to 6 wk and in the case of total and water-soluble nutrients they were assessed after 1 and 42 d. The control treatment had higher NH₃ and CO₂ volatilizations than the treated litter throughout the experiment. EC and pH showed an inverse relationship, whereby the control treatment had high pH and low EC values and the treated litter had low pH and high EC values. After 42 d, nitrogen levels were significantly reduced in the control treatment, whereas the 50 + 50 g/kg treatment had the highest content. Conversely, water-soluble phosphorus levels were much lower in the treated poultry litter after 1 and 42 d. A higher ferric chloride concentration (25 + 50 g/kg) in the blend was more effective than a higher aluminum sulfate concentration (50 + 25 g/kg). These findings demonstrate that a combination of aluminum sulfate and ferric chloride may be a useful amendment for reducing NH₃ and CO₂ volatilizations, pH, and moisture content of poultry litter, which will help in improving poultry productivity, pollution control, and poultry litter fertilizer usage.     

Heterosis and combining ability for body weight in a diallel cross of three chicken genotypes

The aim of the study was to evaluate heterotic and combining ability effects for growth in nine chicken genotypes. A 3?×?3 complete diallel mating system involving two indigenous breeds named Venda (V) and Naked Neck (N) and one commercial broiler breed named Ross 308 (R) were used. The nine genetic groups of crosses were reared up from hatch to 13 weeks of age in deep litter open house. Body weights of 180 chicks (20 chicks per genetic group), recorded at 0, 3, 5, 7, 9, 11, and 13 weeks of age, were used to estimate heterosis, general combining ability (GCA), and specific combining ability (SCA). Results showed that the Ross 308 had the heaviest body weight at all weeks of measurement except for hatch. With respect to crosses, the V × R and its reciprocal cross, R × V had the heaviest body weights at 13 weeks. Heterosis estimates for body weight were higher in the Venda male × Ross 308 female and Venda male and Naked Neck female crosses. GCA was significant (P?≤?0.01) for body weight from hatch to 13 weeks of age while SCA and reciprocal effects were both significant (P?≤?0.05) for body weight at all ages of measurement except for hatch. The Ross 308 gave the highest positive effect of GCA for body weight except for hatch. V × N gave the highest and positive effects of SCA for body weight.     

Effect of cereal type and Xylanase supplementation on nutrient retention and growth performance of broilers

An experiment was conducted to study the effect of cereal (corn, wheat, barley and sorghum) and supplemental enzyme (a mono-component xylanase) in a 4 × 2 factorial arrangement. A 2-phase feeding program (0 to 21 and 21 to 42 d) was used and 4 iso-caloric, iso-nitrogenous diets were formulated containing corn, wheat, barley, or sorghum as the sole cereal. Diets based on each cereal were fed without or with supplemental xylanase (16,000 BXU/kg) to 8 replicate pens of 10 chicks (5 male : 5 female, Cobb 500) each. Growth performance was recorded at 21 or 42 d posthatch. Excreta was quantitatively collected from 18 to 21 and 38 to 41 d for the measurement of the total tract retention of dry matter (DM), nitrogen (N) and neutral detergent fiber (NDF) and apparent metabolizable energy (AME). Ileal digestible energy (IDE) was measured at the end of the study (42 d posthatch) using titanium dioxide as an indigestible marker. For the overall 42 d period, birds fed barley-based diets had lower feed intake (P < 0.05), lower body weight (P < 0.05) and converted feed into gain less efficiently (P < 0.05) compared with the diets based on corn, wheat or sorghum. Xylanase supplementation improved weight gain in diets based on corn, wheat, and sorghum with the exception of barley-based diets (cereal × xylanase interaction, P < 0.05). Xylanase improved the overall feed conversion ratio (1.885 vs. 1.939; P < 0.05) with the effect being independent of the cereal type. The N retention of barley-based diets was lower (P < 0.05) compared with the other cereals, while xylanase improved N retention (P < 0.05) regardless of the cereal type. NDF digestibility differed (P < 0.05) across cereal (barley > wheat > corn > sorghum) and was improved (P < 0.05) by xylanase supplementation. A significant cereal × xylanase interaction (P < 0.05) was observed for energy measurements, where xylanase improved IDE of the corn-based diet, and AME of corn- and wheat-based diets. Results of the current study demonstrate potential of xylanase in improving nutrient retention and growth performance of broilers fed diets based on variety of cereal grains.     

Volatile basic nitrogen measurement in digesta using a Berthelot reaction in automated Skalar instrumentation

The undigested nitrogenous fraction entering the hindgut of chickens is further metabolized by microbiota present producing volatile basic metabolites including amines and ammonia (NH₃). Ammonia increases pH and may result in overgrowth of Clostridium perfringens further producing toxic metabolites that cause dysbacteriosis or necrotic enteritis (NE). There are few reports in chickens examining the production and concentration of nitrogenous metabolites in the hindgut. A Berthelot reaction using an automated flow, reaction and spectrophotometric instrumentation to detect volatile basic nitrogen in the form of NH₃ from cecal contents was carried out. In the Berthelot reaction, NH₃ in the sample is chlorinated to monochloramine using dichloroisocyanuric acid that then reacts with salicylate to form 5-aminosalicylate which is stable under alkaline conditions (pH 12 to 13). After oxidation and oxidative coupling, a coloured complex is formed that can be measured at 660 nm. Cecal contents were collected and pooled from 2 birds per pen with 48 pens total in each of 3 experiments and stored in sealed containers at −20 °C prior to analysis. Experiment 1 compared samples collected from birds fed either no meat and bone meal (MBM) or 6% MBM from d 0 to 14, and samples collected from birds fed either no MBM or 5% MBM from d 14 to 42. All birds were challenged with Eimeria on d 9 and C. perfringens on d 14 and 15. Experiment 2 compared cecal contents from birds fed either 0.5% or 0.9% calcium (Ca), and Exp. 3 compared unchallenged with NE challenge on d 16 and 29. Results demonstrated an increase (P < 0.05) in cecal NH₃ as a result of feeding MBM or high dietary Ca with a corresponding increase in pH. Birds experimentally challenged with NE had lower cecal NH₃ and lower pH on d 16 but not d 29 compared to unchallenged controls. It was concluded that the Berthelot method using Skalar instrumentation equipment is suitable to measure the concentration of volatile nitrogen as NH₃ in cecal contents of chickens.     

Effect of Gender on Factors Affecting Excreta Dry Matter Content of Broiler Chickens

The purpose of this experiment was to investigate the factors affecting water intake in modern genetic lines of broilers that might contribute to problems of wet litter. A total of 128 Ross 308 one-day-old chicks (equal numbers of males and females) were fed commercial grower and finisher rations ad libitum from 10 to 39 d of age, containing 0.2% Ti₂ O₃ as an inert marker. Birds were housed in groups of 4 in metabolism cages. Body weight and feed consumption were recorded weekly from d 10, and water intake was recorded daily. Excreta from each cage were collected daily and, at the end of each week, the DM content of a sample of pooled excreta from each cage was measured. The results showed that male broilers consumed more water (P < 0.001) and produced excreta that had a lower mean DM content (P < 0.05) compared with females. Males grew significantly faster (P < 0.05) compared with females. There was a significant correlation between feed intake, and hence the intake of N and the major minerals, and water intake (r = 0.623, P = 0.001). Despite a higher apparent retention of DM, CP, and feed efficiency in favor of males, variation among cages was high, and differences between gender were not statistically significant. Water intake tended to be correlated to mean live weight gain of the cage (r = 0.301, P = 0.06), and when live weight gain was used as a covariate in the analysis, the gender difference in water intake was no longer significant. In conclusion, it appears that the higher water intake and lower excreta DM content for males is related to their higher feed and water intake. Mineral excretion was similar for males and females; however, males retained significantly more P compared with females. Male broilers had greater tibia bone size and strength parameters, which indicate higher bone mineral deposition compared with females.