Effect of dietary treatments on performance, oocysts shedding and lesion scores in broiler chickens experimentally challenged with Eimeria infection.

Although anticoccidials effectively control coccidiosis, a needed reduction in the reliance on antimicrobials in animal production leads to the exploration of alternative compounds. The present study aimed to test five different dietary treatments to counteract the negative impact of coccidiosis on broiler chickens' health and performance. 1-day-old male Ross 308 broilers (n = 960) were randomly assigned to one of eight treatments, with six cages per treatment (20 birds/cage). To the diet of the broiler chickens of treatments (Trt) 1-5, a synbiotic was added from d0-10. From d10-28, birds of Trt1 and Trt2 were fed synbiotics, whereas birds of Trt3 were fed diets with glutamine, and birds of Trt4 and Trt5 were fed diets with a combination of ß-glucans and betaine. From d28-35 onwards, birds of Trt1 were fed a diet with a synbiotic, whereas birds of Trt2-4 received diets with glutamine, and birds of Trt5 were fed a non-supplemented diet. Birds of the positive control group (PC; Trt6) were fed a standard diet supplemented with an anticoccidial (Decoquinate). The challenged negative control (NCchall; Trt7) and non-challenged negative control (NC) Trt8 were fed a standard diet without anticoccidial or other dietary treatment. At 7 days (d) of age, all birds were inoculated with 1 023, 115, and 512 sporulated oocysts of E. acervulina, E. maxima, and E. tenella, respectively, except for Trt8. Body weight gain (BWG), feed intake, and feed conversion ratio were assessed for each feeding phase (d0-10, d10-28 and d28-35) and overall experimental period (d0-35). Oocyst shedding, Eimeria lesion scores, cecal length, and relative weight were assessed at d13, d22, d28 and d35. Additionally, oocyst shedding was determined at d9 and d17. Litter quality was evaluated at d27 and d34, and footpad lesions at d34. During the starter (d0-10) and finisher (d28-35) periods, performance did not differ between the treatments. During the grower period (d10-28), Trt6 (PC) and Trt8 (NC) chickens had the highest BWG of all treatments (P < 0.001). Dietary treatment had no effect on litter quality and severity of footpad lesions. In the PC group (Trt6), low oocyst excretion and lesion scores were found. When comparing Trt1-5 with NCchall (Trt7), none of the treatments significantly reduced oocyst output or lesion scores. In conclusion, in this experiment, none of the dietary treatments performed similar or better compared to the PC group (Trt6) regarding performance or reducing Eimeria oocyst shedding or lesion scores.

Effects of season, catching method, and thinning on carcass quality and production parameters in 4 different broiler production systems in the Netherlands.

In the Netherlands, poultry meat production has been evolving in recent years toward broiler production systems with slow-growing broilers. In this study the effects of season, catching method, and thinning on carcass quality and production parameters in four different broiler production systems in the Netherlands was evaluated. The data for this study were collected from slaughterhouse data in 2018, 2019, and 2020 and contained information about four different broiler production systems: conventional (fast growing) broilers (CONV), 2 different indoor slow-growing broilers (SGB1 and SGB2), and Better Life 1 Star (BLS) concept with slow-growing broilers. The data set consisted of 14,976, 1,730, 3,713, and 1,121 records (flocks) for CONV, SGB1, SGB2, and BLS, respectively. All three production systems with slow-growing broilers had a lower slaughter weight, average daily gain (ADG), first-week mortality, and total mortality than CONV (no-thinning). ADG of SGB2 and BLS was lower than that of SGB1. Slaughter weight and ADG were the lowest when day-old chicks were placed in March/April and the highest when they were placed in September/October. All slow-growing broiler production systems had a lower footpad lesion score and a lower incidence of hock burns, leg hematomas, breast hematomas, dead-on-arrival chickens (DOA), and total rejects than CONV. Autumn flocks had more hock burns, a higher footpad lesion score, and more wing hematomas than spring flocks. More scabby hips and fewer total rejects were found during the summer months than during the winter months. Thinning flocks had more scabby hips, ammonia burns, and DOAs and fewer hock burns, footpad lesions, wing hematomas, leg hematomas, breast hematomas, and total rejects than no-thinning flocks. Mechanically caught flocks had more ammonia burns, DOAs, and total rejects than manually caught flocks. In conclusion, this study showed that all three production systems with slow-growing broilers had a lower first-week mortality and total mortality and better scores on most carcass quality parameters and welfare indicators than CONV.

The impact of changing toward higher welfare broiler production systems on greenhouse gas emissions: a Dutch case study using life cycle assessment.

In the Netherlands, the Dutch Retail Broiler (DRB) and Better Life one Star (BLS) production systems have been introduced with the aim to improve broiler welfare. Simultaneously, retailers set targets for reduction of greenhouse gas (GHG) emissions in the whole broiler production chain. The GHG emissions of DRB and BLS may differ from conventional systems because of differences in slaughter age, feed intake, and diet composition. The aim of this study was to estimate GHG emissions of the conventional, DRB, and BLS production systems. A deterministic, spreadsheet based model was developed that included the breeder, hatchery, and broiler farm stages. First, the model calculates feed intake of different diets and energy use, based on performance objectives and literature. Selection of feed ingredients for the different types of diets was based on least cost formulation with nutritional constraints for each diet. Second, GHG emissions were estimated from cradle to broiler farm gate for processes along the broiler production chain by using life cycle assessment, and expressed as kg CO2-equivalents per kg live weight (kg CO2-eq/kg LW). Results showed that BLS (3.55 kg CO2-eq/kg LW) had lower GHG emissions compared to conventional (3.65 kg CO2-eq/kg LW) and DRB (3.98 kg CO2-eq/kg LW) at the broiler farm gate. Emissions from land use change (LUC) from feed production, mainly from soybean products, had highest impact on total GHG emissions (>50%) for the systems and these soybean products had the lowest inclusion in the diets of the BLS production system. Sensitivity analyses showed that variation in slaughter weight and feed intake could result in overlap of GHG emissions between systems. When soybean products were sourced from a country with low LUC emissions, conventional (1.37 kg CO2-eq/ kg LW) had the lowest GHG emissions and BLS (1.79 kg CO2-eq/kg LW) the highest. This study showed that origin of and including or excluding LUC emissions from soybean production results in different conclusions for achieving the GHG emissions reduction targets set by retailers.

Nutritional interventions to support broiler chickens during Eimeria infection.

Different combinations of gut health-promoting dietary interventions were tested to support broilers during different stages of Eimeria infection. One-day-old male Ross 308 broilers (n = 720) were randomly assigned to one of 6 dietary treatments, with 6 pens per treatment and 20 birds per pen, for 35 d. At 7 d of age (d7), all birds were inoculated with 1000, 100, and 500 sporulated oocysts of E. acervulina, E. maxima, and E. tenella, respectively. A 4-phase feeding schedule was provided. The dietary treatments (TRT) 1 to 4 included the basal diet supplemented with multispecies probiotics from d0 to 9 and coated butyrate and threonine from d28 to 35 but received four different combinations of prebiotics and phytochemicals from d9 to 18 and d18 to 28. The basal diet for the positive control (PC, TRT5) included diclazuril as a anticoccidial. The negative control (NC, TRT6) contained no anticoccidial. Performance was assessed for each feeding phase, and oocyst output, Eimeria lesion scores, cecal weight, litter quality, and footpad lesions were assessed at d14, d22, d28, and d35. Body weight gain (BWG) and feed intake (FI) were not affected by dietary treatment. PC broilers had the best feed conversion ratio (FCR) of all treatments from d0 to 35 (P < 0.001). None of the dietary treatments resulted in better litter quality or reduced footpad lesions compared to the PC. Moreover, the PC was most effective in reducing oocyst output and lesion scores compared to all other treatments. However, broilers that received the multispecies probiotics (d0 to 9), saponins (d9 to 18), saponins, artemisin, and curcumin (d18 to 28), and coated butyrate and threonine (d28 to 35) had the best FCR (P < 0.001) and lowest oocyst output and lesion scores compared to other dietary treatments. This study suggests that although the tested compounds did not perform as well as the anticoccidial, when applied in the proper feeding period, they may support bird resilience during coccidiosis infection.

Low-calcium diets increase duodenal mRNA expression of calcium and phosphorus transporters and claudins but compromise growth performance irrespective of microbial phytase inclusion in broilers.

The hypothesis that dietary inclusion of microbial phytase improves apparent calcium (Ca) digestibility thereby allowing a lower dietary Ca inclusion without compromising growth performance was tested. One-day-old male Ross 308 broilers (25 birds/pen, 9 pens/treatment) were assigned to 8 experimental diets containing one of 4 dietary Ca to retainable P (rP) ratios (1.3, 1.8, 2.3, and 2.8) with (1,000 FTU/kg) or without microbial phytase. On d 21 to 23, digesta from different intestinal segments of 8 birds per pen were collected to determine apparent Ca and P digestibility. Mid duodenal mucosa was collected for expression of Ca (CaBP-D28k, PMCA1) and P (NaPi-IIb, PiT-1, PiT-2, and XPR1) transporters by RT-qPCR. Dietary phytase inclusion in low Ca/rP diets increased Ca digestibility in the distal ileum (Pinteraction = 0.023) but not the proximal or distal jejunum. Broilers receiving the lowest Ca/rP displayed the lowest body weight gain, highest feed conversion ratio (P < 0.001), and lowest tibia strength, irrespective of dietary phytase inclusion. Incremental dietary Ca/rP linearly reduced P digestibility to a greater extent in the absence of phytase in the distal jejunum and ileum (Pinteraction = 0.021 and 0.001, respectively). Incremental dietary Ca/rP linearly reduced serum P more in phytase-free diets (Pinteraction < 0.001), and lowered duodenal expression of P transporters NaPi-IIb, PiT-2, and XPR1 (P = 0.052, 0.071 and 0.028, respectively). Incremental dietary Ca/rP linearly increased (P < 0.001) serum Ca irrespective of phytase inclusion, accompanied by a lower (P < 0.001) duodenal expression of Ca transporters CaSR, CaBP-D28k and PMCA1 and Ca-pore forming claudins CLDN-2 and CLDN-12. Dietary phytase increased (P = 0.026) NaPi-IIb but reduced (P = 0.029) CLDN-2 expression. Incremental Ca/rP reduced Ca and P digestibility, increased serum Ca, lowered serum P and inhibited mRNA levels of Ca and P-related transporters, indicating that these transporters and CLDN contribute to the observed effect of dietary Ca and phytase on Ca and P absorption. Despite the improvement in Ca digestibility, dietary phytase did not restore the compromised growth performance and tibia strength of broilers fed a Ca-deficient diet, leading to rejection of the hypothesis.

Effect of low protein diets supplemented with free amino acids on growth performance, slaughter yield, litter quality, and footpad lesions of male broilers.

A study with 884 Ross 308 male broilers, housed in 68 floor pens (0.75 m2) from 0 to 35 days of age was conducted to evaluate the effects of low crude protein (CP) diets, with partial replacement of soybean meal by free amino acids (AA), on performance, slaughter yields, litter quality and footpad lesions. During the first 11 d, all broilers received the same control starter diet (216 g/kg CP, 11.5 g/kg apparent fecal digestible (AFD) lysine, and 2900 kcal/kg AMEn). Thereafter, four experimental feeding programs with different levels of dietary CP (control and control with 1% (CP-1%), 2% (CP-2%) and 3% (CP-3%) less CP units) were provided in both the grower and finisher phase. In the control grower and finisher diet, the CP content was 208 and 198 g/kg, respectively. All diets were formulated to meet or exceed the recommendations concerning AFD AA, and to be iso-caloric within each feeding phase. Feed and water were provided for ad libitum intake during the entire experimental period. None of the low CP feeding programs affected body weight gain, feed intake or mortality from 0 to 35 d. However, CP conversion was improved with the reduction of CP content of the diet. Broilers fed the CP-2% or CP-3% feeding program had an improved feed conversion ratio. Broilers fed the low CP protein feeding programs had a better litter quality and less footpad lesions, compared to broilers fed the control feeding program. Broilers fed the CP-3% feeding program had a lower breast meat yield than broilers fed the control feeding program. Slaughter yields of broilers fed CP-1% or CP-2% feeding program did not differ from the control feeding program. This study demonstrated that the CP content of grower and finisher diets can be reduced by 2.2-2.3% units without adverse effects on growth performance of broilers, while CP reduction seems promising to reduce nitrogen excretion from broiler houses, improve bird welfare, and reduces dependence on vegetable protein sources.

Determination of pre-cecal phosphorus digestibility of inorganic phosphates and bone meal products in broilers.

A broiler study was performed to determine the pre-cecal phosphorus (P) digestibility of 5 P sources, 3 from animal (Delfos, Calfos, and porcine bone meal) and 2 of inorganic (monocalcium phosphate [MCP] and dicalcium phosphate [DCP]) origin. Delfos is processed from bones resulting in a dicalcium phosphate product, and Calfos is processed from bones in which part of the gelatin is removed but in which the hydroxy-apatite matrix is preserved. During the first 14 d, birds were housed in floor pens bedded with wood shavings and received a commercial starter diet. At d 14, broilers were randomly assigned to pens (0.9 m2, 10 birds/pen) with a slatted floor. From d 14 onwards, one of the 6 experimental diets (a basal diet, and 5 diets containing the P sources) was provided. Test diets were replicated 6 times, and the basal diet 8 times. Electron microscopy images of test products were made in order to verify whether the spatial structure of the test products could be related to the pre-cecal P digestibility of the same products. Diets met or exceeded CVB (2011) requirements for all nutrients except for P and were formulated to contain a calcium to total P ratio of between 1.4 and 1.6 and a minimal amount of phytate P. Diets contained 5 g/kg titanium oxide as a marker to determine digestibility of P. At d 24 all birds were euthanized, after which the content of the terminal part of the ileum was sampled. The P digestibility was calculated by linear regression according to World's Poultry Science Association (WPSA) protocol for determination of pre-cecal P digestibility. Pre-cecal P digestibility of MCP, DCP, Delfos, Calfos, and porcine bone meal was 88.5, 82.4, 94.5, 86.9, and 78.2%, respectively. Based on visual inspection of electron microscopy images of test products, the spatial structure of the test products might be related to P digestibility. It is concluded that processing of bone meal increases the pre-cecal P digestibility in broilers.

Effects of floor eggs on hatchability and later life performance in broiler chickens.

Two experiments were conducted in which effects of floor eggs, washed floor eggs, and clean nest eggs were investigated on incubation characteristics and performance in later life of broiler chickens. In both experiments, a young and an older breeder flock were used in a 3×2 factorial design during incubation. In the second experiment, male and female chickens were reared separately until d 35 of age in floor pens. During this grow out trial, an extra group was created in which chickens obtained from clean nest eggs were mixed with chickens obtained from floor eggs, meaning that grow out period was set up as a 4×2×2 factorial design with 4 egg types, 2 breeder ages, and 2 sexes. In both experiments, fertility and hatchability of fertile eggs were lower in floor and washed eggs than in clean nest eggs (hatchability: experiment 1: 74.4 vs. 70.6 vs. 92.6% for floor eggs, washed floor eggs and clean nest eggs, respectively, P<0.001; experiment 2: 78.3 vs. 81.7 vs. 90.2%, respectively, P<0.001). In experiment 2, BW at d 0 of chickens obtained from clean nest eggs was higher than that of chickens from floor eggs and washed floor eggs (41.5 vs. 40.4 and 40.3 g, respectively; P<0.001). This difference disappeared during the grow out period and was absent at slaughter age at d 35 of age. Feed intake (FI), feed conversion ratio (FCR), and mortality during the grow out period were not affected by egg type. Incidence and severity of hock burns and footpad dermatitis were not affected by egg type or breeder age. Litter friability at d 35 of age tended to be lower in pens with chickens obtained from washed floor eggs compared to clean nest eggs. We conclude that incubation of floor eggs or washed floor eggs resulted in lower fertility and hatchability compared to clean nest eggs, but that performance during the grow out period was not affected.

Footpad dermatitis in Dutch broiler flocks: prevalence and factors of influence.

In some European countries, footpad dermatitis (FPD) is measured as an indicator of broiler welfare. Prevalence and seasonal variation of FPD was determined within broiler flocks (fast-growing breeds) in the Netherlands. Samples were taken from 386 Dutch flocks at 8 slaughterhouses during a period of one year. Prevalence of footpad dermatitis was related to background information gathered using a food chain certification scheme to identify possible factors of influence. On average, 35.5% of the broilers had no lesions, whereas 26.1% and 38.4% had mild or severe lesions, respectively. Season, age, thinning of flocks, slaughter age, breed, slaughterhouse, and the interaction between thinning and slaughter age significantly affected severity of FPD. Peak flock FPD scores occurred in flocks where 1-d-old chicks were placed in March and December, whereas flocks placed in warm months, between June and August, displayed lower flock FPD scores. Generally, birds sent to slaughter when thinning a flock displayed less severe FPD than birds from completely depopulated flocks. Severity of FPD decreased with age. Because poultry farmer, hatchery, veterinary practice, and feed manufacturer were included in the model as random factors, it was only possible to assess their contribution relative to each other. The broiler farmer had the largest contribution. Also, a large contribution was found for hatchery, perhaps indicating that broiler quality is important. No relationship was observed between FPD and mortality. Across farms, less severe FPD was observed on farms using antibiotics. However, within farms, FPD was more common in flocks where antibiotics had been used compared with flocks that did not require antibiotic treatment. In conclusion, footpad dermatitis was frequently observed in Dutch fast-growing broiler flocks, and many factors had significant effects on severity of FPD, such as breed, thinning of flocks, age at slaughter, slaughter plant, and hatchery.

Comparison of three different diets for organic broilers: effects on performance and body condition.

1. The aim of this study was to assess the feasibility of 100% organic feed for organic broilers by comparing it with 80% organic feed (situation at the time of the experiment; 2004) and 95% organic feed (alternative). 2. Diets were optimised for nutritional value, allowing a maximum 10% increase in feed price when using 100% organic feedstuffs. This could only be achieved at the expense of the methionine content. 3. The birds were reared from 0 to 3 weeks of age in a broiler house in three groups of 500 broilers each on either an 80, a 95 or a 100% organic starter diet. At 3 weeks of age, they were transferred to 15 pens with an outdoor run. Each treatment group of 500 birds was divided into 5 groups of 95 and given an 80, a 95 or a 100% organic finisher diet. 4. Broilers receiving 100% organic feed reached a lower body weight and grew more slowly than those receiving 95% organic feed, mainly because of a lower feed intake. 5. Broilers on 95 or 100% organic feed had a higher incidence of breast blisters than broilers receiving 80% organic feed. 6. The cost price for meat from broilers that received 80% organic feed was euro1.83 per kg live weight. The cost prices for broilers that received 95 and 100% organic feed were euro1.84 (+0.8%) and euro1.93 (+5.4%) per kg live weight, respectively. 7. In conclusion, 95% organic feed led to a better performance than 100% organic feed in this study. Probably, the lower methionine content in the 100% organic feed negatively affected performance. The results for 95% organic feed were similar to 80% organic feed, except for a higher incidence of breast blisters.