A. Lourens

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.

Energy partitioning during incubation and consequences for embryo temperature: A theoretical approach

In practice, many hatchability and chick quality problems have been related to the control of embryo temperature (ET) during incubation. Within an incubator, set at a constant machine temperature (MT), ET can vary substantially. Embryo temperature is the result of the balance between heat transfer to and from the embryo and heat production (HP) of the embryo. We investigated which factors theoretically could account for the variation in ET within an incubator. First, the effects egg weight, MT, and oxygen availability on HP of embryos were quantified. Differences in HP could be due only to differences in the amount of energy utilized from the egg or to differences in the efficiency of the conversion of energy in the egg to energy in the chicken, indicated as E(YFB). Results of these analyses showed that differences in HP attributable to egg weight or oxygen availability were mainly a result of the amount of energy used from the egg constituents and not of a change in E(YFB). However, at a given MT, this variation in HP could account for a maximum increase in ET of only 1.21°C, suggesting that other factors played a role because in practice within an incubator, larger differences in ET have been found. The most important factor was probably the difference in air velocity within an incubator, resulting in differences in heat transfer. Because of this variation, ET varied within an incubator and with increasing ET, E(YFB) decreased, resulting in an even higher HP and consequently ET. We concluded that this theoretical approach could explain the wide variation in ET, and consequently could explain the negative effects of high ET on hatchability and chick quality found in the literature. This indicates that, in both practice and in incubation experiments, it is of great importance to realize that any factor affecting HP or heat transfer influences ET. We strongly suggest that ET (or eggshell temperature) be controlled in any incubation experiment involving hatchability or energy utilization.

Measuring foot-pad lesions in commercial broiler houses. Some aspects of methodology

For monitoring purposes there is a need for a protocol to measure foot-pad dermatitis (FPD) on-farm. Therefore, we studied the effect of number of birds sampled, number of locations sampled and sampling location in a broiler house on the accuracy of measurement, in order to construct a protocol that can be applied in practice. Samples were taken from eight commercial flocks (Ross 308) at up to ten locations with up to 25 birds sampled per location. Foot-pad lesions were scored in all birds for both feet using the Swedish scoring method. No significant differences in FPD score were found between the first five birds and all birds sampled at a particular location. Although locations near the walls did not differ in FPD score from locations in the central area of a house, the severity of foot-pad lesions was unevenly distributed over the house. A model was constructed showing the inaccuracy related to the number of locations sampled in the house and the number of birds sampled per location. The model shows that in situations with at least five locations differences in inaccuracy are relatively small when a total of 100 birds or more is sampled. Inaccuracy is largest in a flock with variation in foot-pad scores, as compared to flocks with little variation. The results of this experiment can be used to determine the optimal sample size in a commercial broiler house.

Standardized data in the broiler value chain

In the Dutch broiler chain, data are collected as a routine practice. However, there is wide variation in the content of data collected and in data collection systems. This variability hampers the use of field data in management information systems to support decisions. The objective of this study was to analyze the quality of data and to standardize the content of data sets in the broiler production chain. To evaluate the quality of data, data sets from 3 Dutch hatcheries, from 23,637 batches of eggs, were assessed. The quality of data was assessed intuitively based on 7 quality attributes. To standardize the content of the data set, a protocol was proposed and validated. The protocol was validated at 30 breeder farms, 3 hatcheries, and 104 broiler farms by using 3 quality attributes: consistency, uniformity, and completeness. Results of the data quality analysis of the 3 Dutch hatcheries showed that the data sets had some fields with inaccurate, incorrect, inconsistent, nonuniform, incomprehensible, missing relevant, or incomplete data. Results of the validation protocol were as follows: feedback was obtained from 23 (77%) breeder farms, 3 (100%) hatcheries, and 7 (7%) broiler farms. Of all the questions, on average 88% were answered on breeder farms; 57, 65, and 82% were answered at each of the 3 hatcheries, respectively; and 79% were answered on the broiler farms. Data collected at 2 hatcheries were more consistent than those collected at the third hatchery. Hatchery data were less consistent than breeder farm data, but the number of data entries at hatcheries far exceeded the number at the farm level. Data from the hatcheries, breeder farms, and broiler farms were not always uniform, possibly because of differences in management strategies. This protocol enables the listing of relevant and standard contents of a data set whereby information exchange along the chain can be simplified. However, it is recommended that the protocol be supplemented with some rules for data collection and management, for example, that variables must be recorded in the provided fields, and that a variable must have one and only one name or code, the same unit of measurement, and the same definition.

Eggshell temperature manipulations during incubation and in ovo injection of thyroxine are associated with a decreased incidence of cold-induced ascites in broiler chickens

ABSTRACT A hypothesis was tested that eggshell temperature manipulations during incubation and in ovo injection of thyroxine (T4) would help their progeny chicks to better survive the ascites‐inducing condition during the growing period. In experiment 1, a total of 4,800 hatching eggs was randomly arranged in a 2 × 4 factorial design (8 replicates of 75 eggs per treatment), in which the eggs were incubated at a constant eggshell temperature (EST) of 37.8°C throughout the incubation period (CON) or were exposed to 15°C for one h on d 11, 13, 15, and 17 of incubation (EST manipulations; ESTM), and 4 treatment groups of 3 control groups (no injection; INJN, needle pricked; INJP, and sterilized distilled water injection; INJW) and one T4 treatment group (injected with sterilized distilled water containing 65 ng of T4; INJT4). In experiment 2, 240 one‐day‐old male broiler chicks from 2 temperature conditions and injection (INJN and INJT4) treatment groups were reared for 42 d in a completely randomized design with a 2 × 2 factorial arrangement. To induce ascites, all chicks were exposed to a 15°C room temperature from 14 d onwards. Results from experiment 1 showed that second‐grade chicks and yolk sac weight were decreased, and body weight at hatch was increased in the ESTM and INJT4 groups. Also, final body weight was increased in the ESTM group. Ascites mortality rate was decreased in the ESTM and INJT4 groups. In the ESTM and INJT4 groups, the red blood cell (RBC) and the packed cell volume (PCV) count were decreased. In conclusion, the results showed that the ESTM and INJT4 treatments during incubation were associated with improved chick quality, productive performance of broilers, and a decreased incidence of cold‐induced ascites in broiler chickens.

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.